#Langley Monoplane

[lonestarflight]

Langley Aviation 2-4 prototype (NX 29099) on January 19, 1942.

"The first model was the 2-4-65 and flew in 1940. The second model was the 2-4-90 which flew in 1941 and was taken on by the USN as the XNL-1."

"Built in 1941 from mahogany veneers impregnated with vinyl and phenol to conserve strategic materials. However, when the U.S.A. entered the war the phenol and vinyl used in the manufacturing process were found to be in short supply and so no long term manufacture was made."

Martin Jensen at the controls

Power plant 2 x 90 h.p Franklin 4AC

Span 35'2" Length 20'8"

Max speed 135 mph Range 400 miles Service ceiling 13,300 ft

Posted on r/WeirdWings by u/jacksmachiningreveng: link

source

Rudy Arnold Photo Collection, Acc. NASM.XXXX.0356, National Air and Space Museum, Smithsonian Institution.

[usafphantom2]

Ronnie Bell Following

Martin B-10 during exercises over Oahu, Hawaii.

The Martin B-10 was the first all-metal monoplane bomber to go into regular use by the United States Army Air Corps, entering service in June 1934. It was also the first mass-produced bomber whose performance was superior to that of the Army's pursuit aircraft of the time.

The B-10 served as the airframe for the B-12, B-13, B-14, A-15 and O-45 designations using Pratt & Whitney engines instead of Wright Cyclones.

In 1935, the Army ordered an additional 103 aircraft designated B-10B. These had only minor changes from the YB-10. Shipments began in 1935 July. B-10Bs served with the 2d Bomb Group at Langley Field, the 9th Bomb Group at Mitchel Field, the 19th Bomb Group at March Field, the 6th Composite Group in the Panama Canal Zone, and the 4th Composite Group in the Philippines. In addition to conventional duties in the bomber role, some modified YB-10s and B-12As were operated for a time on large twin floats for coastal patrol.

The Martin Model 139 was the export version of the Martin B-10. With an advanced performance, the Martin company fully expected that export orders for the B-10 would come flooding in.

The Army owned the rights to the Model 139 design. Once the Army's orders had been filled in 1936, Martin received permission to export Model 139s, and delivered versions to several air forces. For example, six Model 139Ws were sold to Siam in April 1937, powered by Wright R-1820-G3 Cyclone engines; 20 Model 139Ws were sold to Turkey in September 1937, powered by R-1820-G2 engines.

On 19 May 1938, during the Sino-Japanese War, two Chinese Nationalist Air Force B-10s successfully flew to Japan. However, rather than dropping bombs, the aircraft dropped propaganda leaflets.

At the time of its creation, the B-10B was so advanced that General Henry H. Arnold described it as the air power wonder of its day. It was half again as fast as any biplane bomber, and faster than any contemporary fighter. The B-10 began a revolution in bomber design; it made all existing bombers completely obsolete.

However, the rapid advances in bomber design in the 1930s meant that the B-10 was eclipsed by the Boeing B-17 Flying Fortress and Douglas B-18 Bolo before the United States entered World War II. The B-10's obsolescence was proved by the quick defeat of B-10B squadrons by Japanese Zeros during the invasions of the Dutch East Indies and China.

An abortive effort to modernize the design, the Martin Model 146, was entered into a USAAC long-distance bomber design competition 1934–1935, but lost out to the Douglas B-18 and revolutionary Boeing B-17. The sole prototype was so similar in profile and performance to the Martin B-10 series that the other more modern designs easily "ran away" with the competition.

The B-10 began a revolution in bomber design. Its all-metal monoplane build, along with its features of closed cockpits, rotating gun turrets, retractable landing gear, internal bomb bay, and full engine cowlings, would become the standard for bomber designs worldwide for decades. It made all existing bombers completely obsolete. In 1932, Martin received the Collier Trophy for designing the XB-10.

The B-10 began as the Martin Model 123, a private venture by the Glenn L. Martin Company of Baltimore, Maryland. It had a crew of four: pilot, copilot, nose gunner and fuselage gunner. As in previous bombers, the four crew compartments were open, but it had a number of design innovations as well.

These innovations included a deep belly for an internal bomb bay and retractable main landing gear. Its 600 hp (447 kW) Wright SR-1820-E Cyclone engines provided sufficient power. The Model 123 first flew on 16 February 1932 and was delivered for testing to the U.S. Army on 20 March as the XB-907. After testing it was sent back to Martin for redesigning and was rebuilt as the XB-10.

The XB-10 delivered to the Army had major differences from the original aircraft. Where the Model 123 had NACA cowling rings, the XB-10 had full engine cowlings to decrease drag.[2] It also sported a pair of 675 hp (503 kW) Wright R-1820-19 engines, and an 8 feet (2.4 m) increase in the wingspan, along with an enclosed nose turret. When the XB-10 flew during trials in June, it recorded a speed of 197 mph (317 km/h) at 6,000 ft (1,830 m). This was an impressive performance for 1932.

Following the success of the XB-10, a number of changes were made, including reduction to a three-man crew, addition of canopies for all crew positions, and an upgrade to 675 hp (503 kW) engines. The Army ordered 48 of these on 17 January 1933. The first 14 aircraft were designated YB-10 and delivered to Wright Field, starting in November 1933. The production model of the XB-10, the YB-10 was very similar to its prototype.

Via Flickr

[nebris]

The Kreider-Reisner XC-31 or Fairchild XC-31 was an American single-engined monoplane transport aircraft of the 1930s designed and built by Kreider-Reisner. It was one of the last fabric-covered aircraft tested by the U.S. Army Air Corps.[1] Designed as an alternative to the emerging twin-engined transports of the time such as the Douglas DC-2, it was evaluated by the Air Corps at Wright Field, Ohio, under the test designation XC-941,[1] but rejected in favor of all-metal twin-engined designs.

The XC-31 was built with an aluminum alloy framework covered by fabric, and featured strut-braced wing and fully retractable landing gear, with the main gear units mounted on small wing-like stubs and retracting inwards. An additional novel feature was the provision of main cargo doors that were parallel with the ground to facilitate loading.

Following evaluation by the USAAC, the XC-31 was transferred to NACA, which used it for icing studies at its Langley Research Center.

https://en.wikipedia.org/wiki/Kreider-Reisner_XC-31

[carlosebanegas-blog]

Managing Control Forces.

Managing Control Forces. As airplanes evolved from stick and wire contraptions to awesome supersonic machines, the pilot at the center of it all has not changed. Desirable maximum and minimum levels of pilot stick, yoke, and rudder pedal control forces required to steer and maneuver are much the same, but the engineering solutions that bring these forces about have changed with the times. Desirable Control Force Levels. In 1936 and 1937, NACA research pilots and engineers Melvin N. Gough, A. P. Beard, and William H. McAvoy used an instrumented cockpit to establish maximum force levels for control sticks and wheels. In lateral control the maximums for one hand are 30 pounds applied at a stick grip and 80 pounds applied at the rim of a control wheel. In longitudinal control the maximums are 35 pounds for a stick and 50 pounds for a wheel. Lower forces are desirable and easily attainable with modern artificial feel systems. The Federal Aviation Administration allows higher forces for transport-category airplanes under FAR Part 25. Seventy-five pounds is allowed for temporary application. However, the data compilation for the handbook accompanying MIL-STD-1797, a current military document, shows that a little over 50 percent of male pilots and fewer than 5 percent of female pilots are capable of this force level. Gough-Beard-McAvoy force levels are generally used as maximum limits for conventional stick, yoke, and rudder pedal controllers, but much lower control force levels are specified for artificial-feel systems and for side-stick controls operated by wrist and forearm motions. Background to Aerodynamically Balanced Control Surfaces. When airplanes and their control surfaces became large and airplane speeds rose to several hundred miles per hour, control forces grew to the point where even the Gough Beard-McAvoy force limits were exceeded. Pilots needed assistance to move control surfaces to their full travels against the pressure of the air moving past the surfaces. An obvious expedient was to use those same pressures on extensions of the control surface forward of the hinges, to balance the pressure forces that tried to keep the control surfaces faired with the wing. The actual developmental history of aerodynamically balanced control surfaces did not proceed in a logical manner. But a logical first step would have been to establish a background for design of the balances by developing design charts for the forces and hinge moments for unbalanced control surfaces. That step took place first in Great Britain. Glauert’s calculations were based on thin airfoil theory. W. G. Perrin followed in the next year with the theoretical basis for control tab design. The next significant step in the background for forces and hinge moments for unbalanced control surfaces was NACA pressure distribution tests on a NACA 0009 airfoil, an airfoil particularly suited to tail surfaces. The trends with control surface hinge position along the airfoil chord match Glauert’s thin airfoil theory exactly, but with lower flap effectiveness and hinge moment than the theoretical values. Ames and his associates developed a fairly complex scheme to derive three-dimensional wing and tail surface data from the two-dimensional design charts. That NACA work was complemented for horizontal tails by a collection of actual horizontal tail data for 17 tail surfaces, 8 Russian and 3 each Polish, British, and U.S. Full control surface design charts came later, with the publication of stability and control handbooks in several countries. Horn Balances. The first aerodynamic balances to have been used were horn balances, in which area ahead of the hinge line is used only at the control surface tips. In fact, rudder horn balances appear in photos of the Moisant and Bleriot XI monoplanes of the year 1910. It is doubtful that the Moisant and Bl´eriot horn balances were meant to reduce control forces on those tiny, slow airplanes. However, the rudder and aileron horn balances of the large Curtiss F-5L flying boat of 1918 almost certainly had that purpose. Wind-tunnel measurements of the hinge moment reductions provided by horn balances show an interesting characteristic. Control surface hinge moments arise from two sources: control deflection with respect to the fixed surface and angle of attack of the fixed or main surface. The relationship is given in linearized dimensionless form by the equation hinge moment coefficient equals to the derivative of the hinge moment coefficient with respect to the control surface deflection times control surface deflection with respect to the fixed surface plus the derivative of the hinge moment coefficient with respect to angle of attack of the fixed or main surface times the angle of attack of the fixed or main surface, where the hinge moment coefficient is the hinge moment divided by the surface area and mean chord aft of the hinge line and by the dynamic pressure. Both derivatives are normally negative in sign. A negative derivative of the hinge moment coefficient with respect to the control surface deflection means that when deflected the control tends to return to the faired position. A negative derivative of the hinge moment coefficient with respect to angle of attack of the fixed or main surface means that when the fixed surface takes a positive angle of attack the control floats upward, or trailing edge high. Upfloating control surfaces reduce the stabilizing effect of the tail surfaces. It was discovered that horn balances produce positive changes in the derivative of the hinge moment coefficient with respect to angle of attack of the fixed or main surface, reducing the up floating tendency and increasing stability with the pilot’s controls free and the control surfaces free to float. This horn balance advantage has to be weighed against two disadvantages. The aerodynamic balancing moments applied at control surface tips twist the control surface. Likewise, flutter balance weights placed at the tips of the horn, where they have a good moment arm with respect to the hinge line, lose effectiveness with control surface twist. A horn balance variation is the shielded horn balance, in which the horn leading edge is set behind the fixed structure of a wing or tail surface. Shielded horn balances are thought to be less susceptible to accumulating leading-edge ice. Shielded horn balances are also thought to be less susceptible to snagging a pilot’s parachute lines during bailout. Overhang or Leading-Edge Balances. When control surface area ahead of the hinge line is distributed along the span of the control surface, instead of in a horn at the tip, the balance is called an overhang or a leading-edge balance. Overhang design parameters are the percentage of area ahead of the hinge line relative to the total control surface area and the cross-sectional shape of the overhang. Experimental data on the effects of overhang balances on hinge moments and control effectiveness started to be collected as far back as the late 1920s. Some of these early data are given by Abe Silverstein and S. Katzoff. Airplane manufacturers made their own correlations of the effects of overhang balances, notably at the Douglas Aircraft Company. As in many other disciplines, the pressure of World War II accelerated these developments. Root and his group at Douglas found optimized overhang balance proportions for the SBD-1 Dauntless dive bomber by providing for adjustments on hinge line location and overhang nose shape on the SBD-1 prototype, known as the XBT-2. Root wrote a NACA Advance Confidential Report in May 1942 to document a long series of control surface and other modifications leading to flying qualities that satisfied Navy test pilots. For example, in 1 of 12 horizontal tail modifications that were flight tested, the elevator overhang was changed from an elliptical to a “radial,” or more blunt, cross-section, to provide more aerodynamic balancing for small elevator movements. This was to reduce control forces at high airspeeds. Overhang aerodynamic balance, in combination with spring tabs, continue in use in Douglas transport airplanes, from the DC-6 and DC-7 series right up to the elevators and ailerons of the jet-powered DC-8. The DC-8’s elevator is balanced by a 35-percent elliptical nose overhang balance. Remarkably constant hinge moment coefficient variations with elevator deflection are obtained up to a Mach number of 0.96. George S. Schairer came to the Boeing Company with an extensive control surface development background at Convair and in the Cal Tech GALCIT 10-foot wind tunnel. Although early B-17s had used spring tabs, Schairer decided to switch to leading-edge balances for the B-17E and the B-29 bombers. The rounded nose overhang balances on the B-29s worked generally well, except for an elevator overbalance tendency at large deflection angles. Large elevator angles were used in push-overs into dives for evasive action. William Cook remarks, “A World War II B-29 pilot friend of mine was quite familiar with this characteristic, so the fact that he got back meant this must have been tolerable.” However, overhang balance was not effective for the B-29 ailerons. Forces were excessive. The wartime and other work on overhang aerodynamic balance was summarized by the NACA Langley Research Department. The Toll report remains a useful reference for modern stability and control designers working with overhang aerodynamic balances and other aerodynamic balance types as well. Frise Ailerons. The hinge line of the Frise aileron, invented by Leslie George Frise, is always at or below the wing’s lower surface. If one sees aileron hinge brackets below the wing, chances are that one is looking at a Frise aileron. Frise ailerons were used on many historic airplanes after the First World War, including the Boeing XB-15 and B-17, the Bell P-39, the Grumman F6F-3 and TBF, and the famous World War II opponents – the Spitfire, Hurricane, and Focke-Wulf 190 fighters. Frise ailerons were applied to both the Curtiss-Wright C-46 Commando and the Douglas C-54 Sky master during World War II, to replace the hydraulic boost systems used in their respective prototypes. With the hinge point below the wing surface, an arc drawn from the hinge point to be tangent to the wing upper surface penetrates the wing lower surface some distance ahead of the hinge line, thus establishing an overhang balance. The gap between the aileron and wing can be made as narrow as desired by describing another arc slightly larger than the first. This in fact is typical of the Frise aileron design. The narrow wing-to-aileron gap reduces air flow from the high-pressure wing under surface to the lower pressure wing upper surface, reducing drag. The Frise aileron is less prone to accumulate ice for that same reason. It was promoted by the U.S. Army Air Corps Handbook for Airplane Designers as an anti-icing aileron. The relatively sharp Frise aileron nose develops high velocities and low static pressures when projecting below the wing lower surface, when the aileron goes trailing-edge up. This generally overbalances the up-going aileron. On the other hand, the overbalanced-up aileron is connected by control cables or pushrods to the down-going aileron on the other side of the wing. The sharp Frise nose on that side is within the wing contour; the down aileron is underbalanced. By connecting the up and down sides through the pilot’s controls the combination is made stable, with lowered control forces relative to ailerons without aerodynamic balance. The sharp nose of the Frise aileron, protruding below the wing’s lower surface for trailing edge-up deflections, has been thought to help reduce adverse yaw when rolling. The trailing edge-up aileron is on the down-going wing in a roll. In adverse yaw, the down-going wing moves forward, while the airplane yaws in a direction opposite to that corresponding to a coordinated turn. Flow separation from the Frise aileron sharp nose is supposed to increase drag on the down-going wing, pulling it back and reducing adverse yaw. This happens to some extent, but for normal wing plan forms with aspect ratios above about 6, adverse yaw is actually dominated by the aerodynamic yawing moment due to rolling, and is little affected by Frise ailerons. Adverse yaw must be overcome by good directional stability complemented by rudder deflection in harmony with aileron deflection. A Frise aileron design used on the Douglas SBD-1 Dauntless. This design was the seventh and final configuration tested in 1939 and 1940. Nose shape, wing-to-aileron gap, hinge line position, and gap seal parameters were all varied. Flight test evidence of Frise aileron oscillations on a Waco XCG-3 glider due to alternate stalling and unstalling of the sharp nose at extreme up-aileron travels. The upper photo shows the bulky roll rate recorder. The lower photo is a rate of roll trace for two abrupt full aileron rolls. Aileron oscillations are shown by the ripples at the peak roll rate values. Frise ailerons turned out to have problems on large airplanes, where there is a long cable run from the control yoke to the ailerons. In the development of the Waco XCG-3 glider in 1942, the sharp nose of its Frise ailerons alternately stalled and unstalled when the ailerons were held in a deflected position. This created severe buffeting. The aileron nose stalled at the largest angle, reducing the balancing hinge moment. Control cable stretch allowed the aileron to start back toward neutral. But as the aileron angle reduced the nose unstalled, the aerodynamic balance returned, and the aileron started back toward full deflection, completing the cycle. The fix for the XCG-3 was to limit up-aileron angles from 30 to 20 degrees and to round off the sharp nose to delay stalling of the nose. Modified Frise ailerons, with noses raised to delay stalling, had been tested in Britain by A. S. Hartshorn and F. B. Bradfield as early as 1934. The advantages of raised-nose Frise ailerons were verified in NACA tests on a Curtiss P-40. Beveled trailing edges were added to the raised-nose Frise ailerons on the P-40, to make up for loss in aerodynamic balance at small deflections. Lateral stick force remained fairly linear and very low up to a total aileron deflection of 48 degrees, giving a remarkably high dimensionless roll rate of 0.138 at 200 miles per hour. Aileron Differential. The larger travel of one aileron relative to the other is called aileron differential. Aileron differential is a method of reducing control forces by taking advantage of hinge moment bias in one direction. At positive wing angles of attack, the hinge moment acting on both ailerons is normally trailing-edge up, and we say the ailerons want to float up. Assume that the up-going aileron is given a larger travel than the down-going aileron for a given control stick or wheel throw. Then, the work done by the trailing-edge-up hinge moment acting on the up-going aileron can be nearly as great as the work the pilot does in moving the down-going aileron against its up-acting hinge moment, and little pilot force is needed to move the combination. The differential appropriate for up-float is more trailing-edge-up angle than down. Typical values are 30 degrees up and 15 degrees down. The floating hinge moment can be augmented, or even reversed, by fixed tabs. Aileron up-float, associated with negative values of the hinge moment derivative, is greatest at high wing angles of attack. Neglecting accelerated flight, high wing angles of attack occur at low airspeeds. Thus, aileron differential has the unfortunate effect of reducing aileron control forces at low airspeeds more than at high airspeeds, where reductions are really needed. In addition to the force-lightening characteristic of aileron differential, increased up relative to down aileron tends to minimize adverse yaw in aileron rolls, which is the tendency of the nose to swing initially in the opposite direction to the commanded roll. Adverse yaw in aileron rolls remains a problem for modern airplanes, especially those with low directional stability, such as tailless airplanes. Where stability augmentation is available, it is a more powerful means of overcoming adverse yaw than aileron differential. Balancing or Geared Tabs. Control surface tabs affect the pressure distribution at the rear of control surfaces, where there is a large moment arm about the hinge line. A trailing-edge-up tab creates relative positive pressure on the control’s upper surface and a relative negative pressure peak over the tab-surface hinge line. Both pressure changes drive the control surface in the opposite direction to the tab, or trailing-edge-down. When a tab is linked to the main wing so as to drive the tab in opposition to control surface motion, it is called a balancing or geared tab. Balancing tabs are used widely to reduce control forces due to control surface deflection. They have no effect on the hinge moments due to wing or tail surface angle of attack. Airplanes with balancing tabs include the Lockheed Jet star rudder, the Bell P-39 ailerons, and the Convair 880M. Trailing-Edge Angle and Beveled Controls. The included angle of upper and lower surfaces at the trailing edge, or trailing edge angle, has a major effect on control surface aerodynamic hinge moment. This was not realized by practicing stability and control engineers until well into the World War II era. For example, a large trailing-edge angle is now known to be responsible for a puzzling rudder snaking oscillation experienced in 1937 with the Douglas DC-2 airplane. Quoting from an internal Douglas Company document of July 12, 1937, by L. Eugene Root: The first DC-2s had a very undesirable characteristic in that, even in smooth air, they would develop a directional oscillation. In rough air this characteristic was worse, and air sickness was a common complaint.... It was noticed, by watching the rudder in flight, that during the hunting the rudder moved back and forth keeping time with the oscillations of the airplane. It is common knowledge that the control surfaces were laid out along airfoil lines. Because of this fact, the rearward portion of the vertical surface, or the rudder, had curved sides. It was thought that these curved sides were causing the trouble because of separation of the air from the surface of the rudder before reaching the trailing edge. In other words, there was a region in which the rudder could move and not hit “solid” air, thus causing the movement from side to side. The curvature was increased towards the trailing edge of the rudder in such a way as to reduce the supposedly “dead” area.... The change that we made to the rudder was definitely in the wrong direction, for the airplane oscillated severely.... After trying several combinations on both elevators and rudder, we finally tried a rudder with straight sides instead of those which would normally result from the use of airfoil sections for the vertical surfaces. We were relieved when the oscillations disappeared entirely upon the use of this type of rudder. The Douglas group had stumbled on the solution to the oscillation or snaking problem, reduction of the rudder floating tendency through reduction of the trailing-edge angle. Flat sided control surfaces have reduced trailing-edge angles compared with control surfaces that fill out the airfoil contour. We now understand the role of the control surface trailing edge angle on hinge moments. The wing’s boundary layer is thinned on the control surface’s windward side, or the wing surface from which the control protrudes. Conversely, the wing’s boundary layer thickens on the control surface’s leeward side, where the control surface has moved away from the flow. Otherwise stated, for small downward control surface angles or positive wing angles of attack the wing’s boundary layer is thinned on the control surface bottom and thickened on the control’s upper surface. The effect of this differential boundary layer action for down-control angles or positive wing angles of attack is to cause the flow to adhere more closely to the lower control surface side than to the upper side. In following the lower surface contour the flow curves toward the trailing edge. This curve creates local suction, just as an upward-deflected tab would do. On the other hand, the relatively thickened upper surface boundary layer causes the flow to ignore the upper surface curvature. The absence of a flow curve around the upper surface completes the analogy to the effect of an upward-deflected tab. The technical jargon for this effect is that large control surface trailing-edge angles create positive values of the derivative of the hinge moment coefficient with respect to the control surface deflection and the derivative of the hinge moment coefficient with respect to angle of attack of the fixed or main surface, which are , the floating and restoring derivatives, respectively. The dynamic mechanism for unstable lateral-directional oscillations with a free rudder became known on both sides of the Atlantic a little after the Douglas DC-2 experience. Unstable yaw oscillations were calculated in Britain for a rudder that floated into the wind. This was confirmed in two NACA studies. The aerodynamic connection between trailing-edge angle and control surface hinge moment, including the floating tendency, completed the story. Following the success of the flat-sided rudder in correcting yaw snaking oscillations on the Douglas DC-2, flat-sided control surfaces became standard design practice on Douglas airplanes. William H. Cook credits George S. Schairer with introducing flat-sided control surfaces at Boeing, where they were used first on the B-17E and B-29 airplanes. Trailing edge angles of fabric-covered control surfaces vary in flight with the pressure differential across the fabric. A Douglas C-74 transport was lost in 1946 when elevator fabric bulging between ribs increased the trailing-edge angle, causing pitch oscillations that broke off the wing tips. C-74 elevators were metal-covered after that. Understanding of the role of the trailing-edge angle in aerodynamic hinge moments opened the way for its use as another method of control force management. Beveled control surfaces, in which the trailing-edge angle is made arbitrarily large, is such an application. Beveled control surfaces, a British invention of World War II vintage, work like balancing tabs for small control surface angles. The beveled-edge control works quite well for moderate bevel angles. As applied to the North American P-51 Mustang, beveled ailerons almost doubled the available rate of roll at high airspeeds, where high control forces limit the available amount of aileron deflection. But large bevel angles, around 30 degrees, acted too well at high Mach numbers, causing overbalance and unacceptable limit cycle oscillations. Beveled controls have survived into recent times, used for example on the ailerons of the Grumman/Gulfstream AA-5 Tiger and on some Mooney airplanes. Corded Controls. Corded controls, apparently invented in Britain, are thin cylinders, such as actual cord, fastened to control surfaces just ahead of the trailing edge. They are used on one or both sides of a control surface. Corded controls are the inverse of beveled controls. Bevels on the control surface side that projects into the wind produce relative negative pressures near the bevel that balance the control aerodynamically, reducing operating force. On the other hand, cords on the control surface side that projects into the wind create local positive pressures on the surface just ahead of the cord. This increases control operating force. Cords on both sides of a control surface are used to eliminate aerodynamic overbalance. On one side they act as a fixed trim tab. Very light control forces have been achieved by cut and try by starting with aerodynamically overbalanced surfaces, caused by deliberately oversized overhang balances. Quite long cords correct the overbalance, providing stable control forces. In the cut and try process the cords are trimmed back in increments until the forces have been lightened to the pilot’s or designer’s satisfaction. Adjustable projections normal to the trailing edge, called Gurney flaps, act as one-sided cord trim tabs. Spoiler Ailerons. Spoiler ailerons project upward from the upper surface of one wing, reducing lift on that wing and thus producing a rolling moment. Spoiler ailerons are often the same surfaces used symmetrically to reduce lift and increase drag on large jet airplanes for rapid descents and to assist braking on runways. Spoiler ailerons are generally used either to free wing trailing edges for full-span landing flaps or to minimize wing twist due to aileron action on very flexible wings. The aerodynamic details of spoiler operation are still not completely understood, even after years of experiment and theoretical studies. The aerodynamics of a rapidly opened spoiler has two phases, the opening and steady-state phases. Experimental or wind-tunnel studies of rapidly opening upper-wing surface spoilers show a momentary increase in lift, followed by a rapid decrease to a steady-state value that is lower than the initial value. At a wind speed of 39 feet per second, the initial increase is over in less than a half-second, and steady-state conditions appear in about 3 seconds. Results from the computational fluid dynamics method known as the discrete vortex method also predict the momentary increase in lift and associate it with a vortex shed from the spoiler upper edge in a direction that increases net airfoil circulation in the lifting direction. A subsequent shed vortex from the wing trailing edge in the opposite direction reduces circulation to the steady-state value. While suggestive, experimental flow visualization results do not exist that confirm this vortex model. The Yeung, Xu, and Gu experiments show that providing small clearances between the spoiler lower edge and the wing upper surface reduces the momentary increase in lift following spoiler extension. This is consistent with a small shed vortex from the spoiler lower edge of opposite rotation to the vortex shed at the upper edge. A clearance between spoiler and wing surface of this type has also been used to reduce buffet. Separation behind an opened spoiler on a wing upper surface causes distortion of the external or potential flow that is similar to the effect of a flap-type surface with trailing-edge-up deflection. In the latter case, streamlines above the wing are raised toward the wing trailing edge. The effective wing camber is negative in the trailing-edge region, causing a net loss in circulation and lift. The difference in the two cases is that the effective wing trailing edge in the spoiler case is somewhere in the middle of the separated region, instead of at the actual trailing edge, as in the flap-type surface case. The hinge moments of ordinary hinged-flap and slot lip spoiler ailerons are high; brute hydraulic force is used to open them against the airstream. Retractable arc and plug spoiler ailerons are designed for very low hinge moments and operating forces. Although aerodynamic pressures on the curved surfaces of these ailerons are high, the lines of action of these pressures are directed through the hinge line and do not show up as hinge moments. Hinge moments arise only from pressure forces on the ends of the arcs and from small skin friction forces on the curved surfaces. A very early application of plug ailerons was to the Northrop P-61 Black Widow, which went into production in 1943. The P-61 application illustrates the compromises that are needed at times when adapting a device tested in a wind tunnel to an actual airplane. The plug aileron is obviously intended to work only in the up position. However, it turned out not to be possible to have the P-61 plug ailerons come to a dead stop within the wing when retracting them from the up position. The only practical way to gear the P-61 plug ailerons to the cable control system attached to the wheel was by extreme differential. Full up-plug aileron extension on one side results in a slight amount of down-plug aileron angle on the other side. The down-plug aileron actually projects slightly from the bottom surface of the wing. Down-plug aileron angles are shielded from the airstream by a fairing that looks like a bump running span wise. Plug-type spoiler ailerons are subject to nonlinearities in the first part of their travel out of the wing. Negative pressures on the wing’s upper surface tend to suck the plugs out, causing control overbalance. Centering springs may be needed. There can be a small range of reversed aileron effectiveness if the flow remains attached to the wing’s upper surface behind the spoiler for small spoiler projections. Nonlinearities at small deflections in the P-61 plug ailerons were swamped out by small flap-type ailerons, called guide ailerons, at the wing tips. Early flight and wind-tunnel tests of spoilers for lateral control disclosed an important design consideration, related to their chord wise location on the wing. Spoilers located about mid-chord are quite effective in a static sense but have noticeable lags. That is, for a forward-located spoiler, there is no lift or rolling moment change immediately after an abrupt up-spoiler deflection. Since airfoil circulation and lift are fixed by the Kutta trailing edge condition, the lag is probably related to the time required for the flow perturbation at the forward-located spoiler to reach the wing trailing edge. Spoilers at aft locations, where flap-type ailerons are found, have no lag problems. Another spoiler characteristic was found in early tests that would have great significance when aileron reversal became a problem. Spoiler deflections produce far less wing section pitching moment for a given lift change than ordinary flap-type ailerons. The local section pitching moment produced by ailerons twists the wing in a direction to oppose the lift due to the aileron. This is why spoilers are so common as lateral controls on high-aspect ratio wing airplanes. Open slot-lip spoilers on the Boeing 707. Note the exposed upper surface of the first element of the flaps. The open spoilers destroy the slot that ordinarily directs the flow over the flap upper surface, reducing flap effectiveness. The reduced lift improves lateral control power when the spoilers are used asymmetrically or the airplane’s braking power when deployed symmetrically on when the ground. Slot-lip spoiler ailerons are made by hinging the wing structure that forms the upper rear part of the slot on slotted landing flaps. Since a rear wing spar normally is found just ahead of the landing flaps, hinging slot-lip spoilers and installing hydraulic servos to operate them is straightforward. There is a gratifying amplification of slot-lip spoiler effectiveness when landing flaps are lowered. The landing flap slot is opened up when the slot-lip spoiler is deflected up, reducing the flap’s effectiveness on that side only and increasing rolling moment. Internally Balanced Controls. Another control surface balance type that appeared about the same time as beveled controls was the internally balanced control. This control is called the Westland-Irving internal balance in Great Britain. Internally balanced controls are intended to replace the external aerodynamic balance, a source of wing drag because of the break in the wing contour. In the internally balanced control the surface area ahead of the hinge line is a shelf contained completely within the wing contour. Unless the wing is quite thick and has its maximum thickness far aft, mechanical clearance requires either that the shelf be made small, restricting the available amount of aerodynamic balance, or control surface throws be made small, restricting effectiveness. By coincidence, internally balanced controls appeared about the same time as the NACA 65-, 66-, and 67-series airfoil sections. These are the laminar flow airfoils of the 1940s and 1950s. Internally balanced ailerons are natural partners of laminar flow airfoil sections, since aerodynamic balance is obtained without large drag-producing surface cutouts for the overhang. Not only that, but the 66 and 67 series have far aft locations of wing maximum thickness. This helps with the clearance problem of the shelf inside of the wing contour. An internal balance modification that gets around the mechanical clearance problem on thin airfoils is the compound internal balance. The compound shelf is made in two, or even three, hinged sections. The forward edge of the forward shelf section is hinged to fixed airplane structure, such as the tail or wing rear spar. The first application of the compound internal balance appears to have been made by William H. Cook, on the Boeing B-47 Stratojet. Internally balanced elevators and the rudder of the Boeing B-52 have compound shelves on the inner sections of the control surfaces and simple shelves on the outer sections. Compound internal balances continue to be used on Boeing jets, including the 707, 727, and 737 series. The 707 elevator is completely dependent on its internal aerodynamic balance; there is no hydraulic boost. According to Cook, in an early Pan American 707, an inexperienced co-pilot became disoriented over Gander, New found land, and put the airplane into a steep dive. The pilot, Waldo Lynch, had been aft chatting with passengers. He made it back to the cockpit and recovered the airplane, putting permanent set into the wings. In effect, this near-supersonic pullout proved out the 707’s manual elevator control. The 707’s internally balanced ailerons are supplemented by spoilers. The later Boeing 727 used dual hydraulic control on all control surfaces, but internal aerodynamic balance lightens control forces in a manual reversion mode. An electrically driven adjustable stabilizer helps in manual reversion. At least one 727 lost all hydraulic power and made it back using manual reversion. Internally balanced controls were used on a number of airplanes of the 1940s and 1950s. The famous North American P-51 Mustang had internally balanced ailerons, but they were unsealed, relying on small clearances at the front of the shelf to maintain a pressure differential across the shelf. The Curtiss XP-60 and Republic XF-12 both used internally balanced controls, not without operational problems on the part of the XP-60. Water collected on the seal, sometimes turning to ice. Flying or Servo and Linked Tabs. Orville R. Dunn gave 30,000 pounds as a rule-of-thumb upper limit for the weight of transport airplanes using leading-edge aerodynamic balance. Dunn considered that airplanes larger than that would require some form of tab control, or else hydraulically boosted controls. The first really large airplane to rely on tab controls was the Douglas B-19 bomber, which flew first in 1941. The B-19 used pure flying or servo tab control on the rudder and elevator and a plain-linked tab on the ailerons. In a flying tab the pilot’s controls are connected only to the tab itself. The main control surfaces float freely; no portion of the pilot’s efforts go into moving them. A plain-linked tab on the other hand divides the pilot’s efforts in some proportion between the tab and the main surface. The rudder of the Douglas C-54 Sky master transport uses a linked tab. Roger D. Schaufele recalls some anxious moments at the time of the B-19’s first flight out of Clover Field, California. The pilot was Air Corps pilot Stanley Olmstead, an experienced hand with large airplanes. This experience almost led to disaster, as Olmstead “grabbed the yoke and rotated hard” at liftoff, as he had been accustomed to doing on other large airplanes. With the flying tab providing really light elevator forces, the B-19 rotated nose up to an estimated 15 to 18 degrees, in danger of stalling, before Olmstead reacted with forward control motion. Flying tabs are quite effective in allowing large airplanes to be flown by pilot effort alone, although the B-19 actually carried along a backup hydraulic system. A strong disadvantage is the lack of control over the main control surfaces at very low airspeeds, such as in taxi, the early part of takeoffs, and the rollout after landing. The linked tab is not much better in that the pilot gets control over the main surface only after the tab has gone to its stop. Still, by providing control for the B-19, the world’s largest bomber in its time, flying and linked tabs, and the Douglas Aircraft Company engineers who applied them, deserve notice in this history. An apocryphal story about the B-19 flying tab system illustrates the need for a skeptical view of flying tales. MIT’s Otto Koppen was said to have told of a B-19 vertical tail fitted to a B-23 bomber, an airplane the size of a DC-3, to check on the flying tab scheme. The point of the story is that the B-23 flew well with its huge vertical tail. Koppen said this proved that a vertical tail could not be made too large. Unfortunately, this never occurred. Orville Dunn pointed out that the B-23 came years after the B-19, and it didn’t happen. Spring Tabs. Spring tabs overcome the main problem of flying tabs, which do not provide the pilot with control of the main surface at low speeds, as when taxiing. In spring tabs, the pilot’s linkage to the tab is also connected to the main surface through a spring. If the spring is quite stiff, good low-speed surface control results. At the same time, a portion of the pilot’s efforts goes into moving the main surface, increasing controller forces. Spring tabs have the useful feature of decreasing control forces at high airspeeds, where control forces usually are too heavy, more than at low airspeeds. At low airspeeds, the spring that puts pilot effort into moving the main surface is stiff relative to the aerodynamic forces on the surface; the tab hardly deflects. The reverse happens at high airspeeds. At high airspeeds the spring that puts pilot effort into moving the main surface is relatively weak compared with aerodynamic forces. The spring gives under pilot load; the main surface moves little, but the spring gives, deflecting the tab, which moves the main surface without requiring pilot effort. The earliest published references to spring tabs appeared as Royal Air craft Establishment publications. NACA publications followed. But the credit for devising a generalized control tab model that covers all possible variations belongs to Orville R. Dunn. The Dunn model uses three basic parameters to characterize spring tab variations, which include the geared tab, the flying tab, the linked tab, and the geared spring tab. Although the derivation of pilot controller force equations for the different tab systems involve only statics and the virtual work principle, the manipulations required are surprisingly complex. As is typical for engineering papers prepared for publication, Dunn provides only bare outlines of equation derivations. Readers of the 1949 Dunn paper who want to derive his final equations should be prepared for some hard labor. Dunn concluded that spring tabs can produce satisfactory pilot forces on subsonic transport-type airplanes weighing up to several million pounds. At the time of Dunn’s paper, spring tabs had indeed been used successfully on the Hawker Tempest, the Vultee Vengeance rudder, all axes of the Canberra, the rudder and elevator of the Curtiss C-46 Commando, the Republic XF-12, and the very large Convair B-36 bomber. They also would be used later on the Boeing B-52 Stratofortress. Dunn’s account of the DC-6 development tells of rapid, almost overnight, linkage adjustments during flight testing. The major concerns in spring tab applications are careful design and maintenance to minimize control system static friction and looseness in the linkages. The B-19 experience encouraged Douglas engineers to use spring tabs for many years afterwards. Both the large C-124 and C-133 military transports were so equipped. The DC-6, 7, 8, and 9 commercial transports all have some form of spring tab controls, the DC-8 on the elevator and the DC-9 on all main surfaces, right up to the latest MD-90 version. In that case, the switch was made to a powered elevator to avoid increasing horizontal tail size to accommodate the airplane’s stretch. A powered elevator avoids tab losses and effective tail area reductions because tabs move in opposition to elevator travel. The Douglas DC-8 and -9 elevator control tabs are actually linked tabs, in which pilot effort is shared between the tab and the elevator. This gives the pilot control over the elevator when on the ground. The DC-8 and -9 elevator linked tabs are inboard and rather small. The inboard linked tabs are augmented by outboard geared tabs, which increase the flutter margin over single large linked tabs. The DC-9 elevator controls are hybrid in that hydraulic power comes in when the link tab’s deflection exceeds 10 degrees. Spring tabs serve a backup purpose on the fully powered DC-8 ailerons and rudder and on the DC-9 rudder. The tabs are unlocked automatically and used for control when hydraulic system pressure fails. The same tab backup system is used for the Boeing 727 elevator. The spring tab design for the elevators of the Curtiss C-46 Commando was interesting for an ingenious linkage designed by Harold Otto Wendt. Elevator surfaces must be statically balanced about their hinge lines to avoid control surface flutter. Spring tabs should also be statically balanced about their own hinge lines. Spring tab balance weights and the spring mechanisms add to the elevator’s weight unbalance about its hinge line. Wendt’s C-46 spring tab linkage was designed to be largely ahead of the elevator hinge line, minimizing the amount of lead balance required to statically balance the elevator. Spring tabs appear to be almost a lost art in today’s design rooms. Most large airplanes have hydraulic systems for landing gear retraction and other uses, so that hydraulically operated flight controls do not require the introduction of hydraulic subsystems. Furthermore, modern hydraulic control surface actuators are quite reliable. Although spring tab design requires manipulation of only three basic parameters, designing spring tabs for a new airplane entails much more work for the stability and control engineer than specifying parameters for hydraulic controls. Computer-aided design may provide spring tabs with a new future on airplanes that do not really need hydraulically powered controls. Springy Tabs and Down springs. Sometimes called “Vee” tabs, springy tabs first appeared on the Curtiss C-46 Commando twin-engine transport airplane. Their inventor, Roland J.White, used the springy tab to increase the C-46’s allowable aft center of gravity travel. White was a Cal Tech classmate of another noted stability and control figure, the late L. Eugene Root. Springy tabs increase in a stable direction the variation of stick force with airspeed. A springy tab moves in one direction, with the trailing edge upward. It is freely hinged and is pushed from neutral in the trailing-edge-upward direction by a compression spring. An NACA application mounted the springy tab on flexure pivots. The springy tab principle of operation is that large upward tab angles are obtained at low airspeeds, where the aerodynamic moment of the tab about its own hinge line is low compared with the force of the compression spring. Upward tab angle creates trailing-edgedown elevator hinge moment, which must be resisted by the pilot with a pull force. Pull force at low airspeed is required for stick-free stability. The C-46 springy tabs were called Vee tabs because the no-load-up deflection was balanced aerodynamically by the same down rig angle on a trim tab on the opposite elevator. The C-46 springy tabs were also geared in the conventional sense. The compression spring that operated the C-46’s springy tab was a low-rate or long-travel spring with a considerable preload of 52 pounds. Tab deflection occurred only after the preload was exceeded, making the system somewhat nonlinear. Schematic diagram of the elevator trim and vee-tab installations on the Curtiss C-46 Commando. The vee tab augments static longitudinal stick-free stability. Springy tabs were also used successfully on the Lockheed Electra turboprop. Although White is considered the springy tab’s inventor and was the applicant for a patent on the device, it may have been invented independently by the late C. Desmond Pengelly. Springy tabs are not in common use currently because of potential flutter. Irreversible tab drives are preferred to freely hinged tabs from a flutter standpoint. A flutter-conservative means of accomplishing the same effect as a springy tab is the down spring. This is a long-travel spring connected between the elevator linkage and airplane fixed structure. The stick or yoke is pulled forward by the long-travel spring with an essentially constant force. Elevator aerodynamic hinge moment, which would normally fair the elevator to the stabilizer, is low compared with the spring force, and the pilot is obliged to use pull force to hold the elevator at the angle required for trim. As with the springy tab, this provides artificial stick-free stability. Down springs are often found in light airplanes. If the yoke rests against its forward stop with the airplane parked, and a pull force is needed to neutralize yoke travel, either a down spring is installed or, less likely, the elevator has mass unbalance. All-Movable Controls. All-movable tail surfaces became interesting to stability and control designers when high Mach number theory and transonic wind-tunnel tests disclosed poor performance of ordinary flap-type controls. Effectiveness was down, and hinge moments were up. More consistent longitudinal and directional control over the entire speed range seemed possible with all-moving surfaces. However, application of all-moving or slab tail surfaces had to await reliable power controls. One of the first all-moving tail applications was the North American F-100 Super Sabre. According to William E. Cook, a slab horizontal tail was considered for the B-52 and rejected only because of the unreliability of hydraulics at the time. In modern times, there is the Lockheed 1011 transport, with three independent hydraulic systems actuating its all-moving horizontal tail. Of course, modern fighter airplanes, starting with the F-4 in the United States; the Lightning, Scimitar, and Hawk in Britain; and the MiG-21 in Russia, have all-moving horizontal tails. An interesting application is the all-moving tail on a long series of Piper airplanes, beginning with the Comanche PA-24 and continuing with the Cherokee and Arrow series. A geared tab is rigged in the anti-balance sense. The geared tab adds to both control force and surface effectiveness. Fred Weick credits John Thorp with this innovation, inspired by a 1943 report by Robert T. Jones. Mechanical Control System Design Details. Connections between a pilot and the airplane’s control surfaces are in a rapid state of evolution, from mechanical cables or push rods, to electrical wires, and possibly to fiber optics. Push rod mechanical systems have fallen somewhat into disuse; flexible, braided, stainless steel wire cable systems are now almost universal. In an unpublished Boeing Company paper, William H. Cook reviews the mature technology of cable systems: The multi-strand 7×19 flexible steel cables usually have diameters from 1/8 to 3/16 inch. They are not easily damaged by being stepped on or deflected out of position. They are usually sized to reduce stretch, and are much over-strength for a 200-pound pilot force. The swaged end connections, using a pin or bolt and cotter pin, are easily checked. The turnbuckles which set tension are safety-wired, and are easily checked. A Northwest Airlines early Electra crashed due to a turnbuckle in the aileron system that was not secured with safety wire wrap. Since the cable between the cockpit and the control is tensioned, the simplest inspection is to pull it sideways anywhere along its length to check both the tension and the end connections. In a big airplane with several body sections this is good assurance. To avoid connections at each body section joint, the cable can be made in one piece and strung out after joining the sections. The avoidance of fittings required to join cable lengths also avoids the possibility of fittings jamming at bulkheads. Since the cable is rugged, it can be installed in a fairly open manner.... Deterioration of the cables from fatigue, as can happen in running over pulleys, or from corrosion, can be checked by sliding a hand over its length. If a strand of the 7×19 cable is broken, it will “draw blood.” A recurrent problem in all mechanical flight control systems is possible rigging in reverse. This can happen on a new airplane or upon re-rigging an old airplane after disassembly. Modern high-performance sailplanes are generally stored in covered trailers and are assembled only before flying. Sailplane pilots have a keen appreciation of the dangers of rigging errors, including reversals. Preflight checks require the ground crew to resist pilot effort by holding control surfaces and to call out the sense of surface motions, up or down, right or left. A few crossed cable control accidents have occurred on first flights. The aileron cables were crossed for the first flight of Boeing XB-29 No. 2, but the pilot aborted the takeoff in time. Crossed electrical connections or gyros installed in incorrect orientations are a more subtle type of error, but careful preflight procedures can catch them, too. Hydraulic Control Boost. Control boost by hydraulic power refers to the arrangement that divides aerodynamic hinge moment in some proportion between the pilot and a hydraulic cylinder. A schematic for an NACA experimental boosted elevator for the Boeing B-29 airplane shows the simple manner in which control force is divided between the pilot and the hydraulic boost mechanism. Boosted controls were historically the first hydraulic power assistance application. By retaining some aerodynamic hinge moments for the pilot to work against two things are accomplished. First, the control feel of an unaugmented airplane is still there. The pilot can feel in the normal way the effects of high airspeeds and any buffet forces. Second, no artificial feel systems are needed, avoiding the weight and complexity of another flight subsystem. Hydraulic power boost came into the picture only at the very end of World War II, on the late version Lockheed P-38J Lightning, and only on that airplane’s ailerons. After that, hydraulic power boost was the favored control system arrangement for large and fast airplanes, such as the 70-ton Martin XPB2M-1 Mars flying boat, the Boeing 307 Stratoliner, and the Lockheed Constellation series transports, until irreversible power controls took their place. Early Hydraulic Boost Problems. Early hydraulic boosted controls were notoriously unreliable, prone to leakage and outright failures. Among other innovative systems at the time, the Douglas DC-4E prototype airplane had hydraulic power boost. Experience with that system was bad enough to encourage Douglas engineers to face up to pure aerodynamic balance and linked tabs for the production versions of the airplane, the DC-4 or C-54 Sky master. A similar sequence took place at the Curtiss-Wright plant in St. Louis, where the Curtiss C-46Commandowasdesigned.Atagrossweightof45,000 pounds, the C-46 exceeded O.R. Dunn’s rule of thumb of 30,000 pounds for the maximum weight of a transport with leading-edge aerodynamic balance only. Thus, the CW-20, a C-46 prototype, was fitted initially with hydraulic boost having a 3:1 ratio, like those on the Douglas DC-4E Sky master prototype and the Lockheed Constellation. However, maintenance and outright failure problems on the C-46’s hydraulic boost were so severe that the Air Materiel Command decreed that the airplane be redesigned to have aerodynamically balanced control surfaces. The previous successful use of aerodynamic balance on the 62,000-pound gross weight Douglas C-54 motivatedtheAirCorpsdecree.Thiswasthestartofthe“C-46BoostEliminationProgram,” which kept one of this book’s authors busy during World War II. Another airplane with early hydraulically boosted controls was the Boeing 307 Stratoliner. Hydraulic servos were installed on both elevator and rudder controls. Partial jamming of an elevator servo occurred on a TWA Stratoliner. This was traced to deformation of the groove into which the piston’s O ring was seated. The airplane was landed safely. Irreversible Powered Controls. An irreversible power actuator for aerodynamic control surfaces is in principle much simpler than hydraulic control boost. There is no force balancing linkage between the pilot and the hydraulic cylinder to be designed. Irreversible powered controls are classic closed loops in which force or torque is applied until a feedback signal cancels the input signal. They are called irreversible because aerodynamic hinge moments have no effect on their positions. An easily comprehended irreversible power control unit is that in which the control valve body is hard-mounted to the actuation or power cylinder. Pilot control movement or electrical signals move the control valve stem off center, opening ports to the high pressure, or supply hydraulic fluid and low pressure, or sump hydraulic fluid. Piping delivers high-pressure fluid to one side of the piston and low-pressure fluid to the other. The piston rod is anchored to structure and the power cylinder to the control surface. When the power cylinder moves with respect to structure in response to the unbalanced pressure it carries the control valve body along with it. This centers the control valve around the displaced stem, stopping the motion. The airplane’s control surface has been carried to a new position, following up the input to the control valve in a closed-loop manner. The first irreversible power controls are believed to have been used on the Northrop XB-35 and YB-49 flying wing airplanes. Irreversibility was essential for these airplanes because of the large up-floating elevon hinge moment at high angles of attack, as the stall was approached. This was unstable in the sense that pilot aft-yoke motion to increase the angle of attack would suddenly be augmented by the elevon’s own up-deflection. One of the N9MflyingscalemodelsoftheNorthropflyingwingswaslostduetoelevonup-float. The YB-49’s irreversible actuators held the elevons in the precise position called for by pilot yoke position, eliminating up-float. Other early applications of irreversible power controls were to the de Havilland Comet; the English Electric Lightning P1.A, which first flew in 1954; and the AVRO Canada CF-105 Arrow, which first flew in 1958. Howard believes that the Comet application of irreversible powered controls was the first to a passenger jet. The U.K. Air Registration Board “made the key decision to accept that a hydraulic piston could not jam in its cylinder, a vital factor necessary to ensure the failure-survivability of parallel multiple-power control connections to single surfaces.” While irreversible power controls are simple in principle, it was several years before they could be used routinely on airplanes. The high powers and bandwidths associated with irreversible power controls, as compared with earlier boosted controls, led to system limit cycling and instabilities involving support structures and oil compressibility. These problems were encountered and solved in an ad hoc manner by mechanical controls engineer T. A. Feeney for the Northrop flying wings on a ground mockup of the airframe and its control system, called an iron bird. An adequate theory was needed for power control limit cycle instability, to explain the roots of the problem. This was presented by D. T. McRuer at a symposium in 1949 and subsequently published. The post–World War II history of gradual improvements in the design of irreversible power controls is traced by Robert H. Maskrey and W. J. Thayer. They found that Tinsley in England patented the first two-stage electromechanical valve in 1946. Shortly afterwards, R. E. Bayer, B. A. Johnson, and L. Schmid improved on the Tinsley design with direct mechanical feedback from the second-stage valve output back to the first stage. Engineers at the MIT Dynamic Analysis and Controls Laboratory added two improvements to the two-stage valve. The first was the use in the first stage of a true torque motor instead of a solenoid. The second improvement was electrical feedback of the second-stage valve position. In 1950, W. C. Moog, Jr., developed the first two-stage servo valve using a frictionless first-stage actuator, a flapper or vane. Valve bandwidths of up to 100 cycles per second could be attained. The next significant advance was mechanical force feedback in a two-stage servo valve, pioneered by T. H. Carson, in 1953. The main trends after that were toward redundancy and integration with electrical commands from both the pilot and stability augmentation computers. In general, satisfactory irreversible power control designs require attention to many details, as described by Glenn. In addition to the limit cycling referred to previously, these include minimum increment of control, position and time lags, surface positioning accuracy, flexibility, spring back, hysteresis, and irreversibility in the face of external forces. Artificial Feel Systems. Since irreversible power controls isolate the pilot from aerodynamic hinge moments, artificial restoration of the hinge moments, or “artificial feel,” is required. Longitudinal artificial feel systems range in complexity from simple springs, weights, and stick dampers to computer-generated reactive forces applied to the control column by servos. A particularly simple artificial feel system element is the bob weight. The bob weight introduces mass unbalance into the control circuit, in addition to the unbalances inherent in the basic design. That is, even mass-balanced mechanical control circuits have inertia that tends to keep the control sticks, cables, and brackets fixed while the airplane accelerates around them. Bob weights are designed to add the unbalance, creating artificial pilot forces proportional to airplane linear and angular accelerations. They also have been used on airplanes without irreversible power controls, such as the Spitfire and P-51D. The most common bob weight form is a simple weight attached to a bracket in front of the control stick. Positive normal acceleration, as in a pull-up, requires pilot pull force to overcome the moment about the stick pivot of increased downward force acting on the bob weight. There is an additional pilot pull force required during pull-up initiation, while the airplane experiences pitching acceleration. The additional pull force arises from pitching acceleration times the arm from the center of gravity to the bob weight. Without the pitching acceleration component, the pilot could get excessive back-stick motions before the normal acceleration builds up and tends to pull the stick forward. In the case of the McDonnell Douglas A-4 airplane’s bob weight installation, an increased pitching acceleration component is needed to overcome over control tendencies at high airspeeds and low altitudes. A second, reversed bob weight is installed at the rear of the airplane. The reversed bob weight reduces the normal acceleration component of stick force but increases the pitching acceleration component. Another interesting artificial feel system element is the q-spring. As applied to the Boeing XB-47 rudder the q-spring provides pedal forces proportional to both pedal deflection and airplane dynamic pressure, or q. Total pressure is put into a sealed container having a bellows at one end. The bellows is equilibrated by static pressure external to the sealed container and by tension in a cable, producing a cable force proportional to the pressure difference, or q. Pilot control motion moves an attachment point of that cable laterally, providing a restoring moment proportional to control motion and to dynamic pressure. It appears that a q-spring artificial feel system was first used on the Northop XB-35 and B-49 flying wing elevons, combined with a bob weight. Q-spring artificial feel system versions have survived to be used on modern aircraft, such as the elevators of the Boeing 727, 747, and 767; the English Electric Lightning; and the McDonnell Douglas DC-10. Hydraulic rather than pneumatic springs are used, with hydraulic pressure made proportional to dynamic pressure by a regulator valve. In many transport airplanes the force gradient is further modulated by trim stabilizer angle. Stabilizer angle modulation, acting through a cam, provides a rough correction for the center of gravity position, reducing the spring force gradient at forward center of gravity positions. Other modulations can be introduced. Advanced artificial feel systems are able to modify stick spring and damper characteristics in accordance with a computer program, or even to apply forces to the stick with computer-controlled servos. Fly-by-Wire. In fly-by-wire systems control surface servos are driven by electrical inputs from the pilot’s controls. Single-channel fly-by-wire has been in use for many years, generally through airplane automatic pilots. For example, both the Sperry A-12 and the Honeywell The Boeing 767 elevator control system, possibly the last fly-by-cable or mechanical flight control system to be designed for a Boeing transport. Each elevator half is powered by three parallel hydro mechanical servo actuators. Cam overrides and shear units allow separation of jammed system components. C-1 autopilots of the 1940s provided pilot flight control inputs through cockpit console controls. However, in modern usage, fly-by-wire is defined by multiple redundant channel electrical input systems and multiple control surface servos, usually with no or very limited mechanical backup. According to Professor Bernard Etkin, a very early application of fly-by-wire technology was to the Avro Canada CF-105 Arrow, a supersonic delta-winged interceptor that first flew in 1958. A rudimentary fly-by-wire system, with a side-stick controller, was flown in 1954 in a NASA-modified Grumman F9F. The NASA/Dryden digital fly-by wire F-8 program was another early development. You can consult Schmitt and Tomayko for the interesting history of airplane fly-by-wire. The Boeing 767 is probably the last design from that company to retain pilot mechanical inputs to irreversible power control actuators, or fly-by-cable. The 767 elevator control schematic shows a high redundancy level, with three independent actuators on each elevator, each supplied by a different hydraulic system. Automatic pilot inputs to the system require separate actuators, since the primary surface servos do not accept electrical signals. The Boeing 777 is that company’s first fly-by-wire airplane, in which the primary surface servos accept electrical inputs from the pilot’s controls. With the Boeing 777, flyby-wire can be said to have come of age in having been adopted by the very conservative Boeing Company. Fly-by-wire had previously been operational on the Airbus A320, 330, and A340 airplanes shows the redundancy level provided on the Boeing 777 control actuators. PFC refers to primary flight control computers, the ACE are actuator control electronic units, the AFDC are autopilot flight director Controls, the PSA are power supplies, and the FSEU are secondary control units. Note the cross-linkages of the ACEs to the hydraulic power sources. Redundancy level provided on the Boeing 777 Transport. P.F.C. is the primary flight computer, A.C.E. the actuator control electronics, A.F.D.C. the autopilot flight director, P.S.A. the conditioned power, and F.S.E.U. the flap slat electronics unit. McLean gives interesting details on the 777 and A320 fly-by-wire systems: Boeing 777. To prevent pilots exceeding bank angle boundaries, the roll force on the column increases as the bank angle nears 35 degrees. FBW enables more complex inter-axis coupling than the traditional rudder cross feed for roll/yaw coordination which results in negligible sideslip even in extreme maneuvers...the yaw gust damper ...senses any lateral gust and immediately applies rudder to alleviate loads on the vertical fin. The Boeing 777 has an FBW system which allows the longitudinal static margin to be relaxed – a 6 percent static margin is maintained...stall protection is provided by increasing column control forces gradually with increases in angle of attack. Pilots cannot trim out these forces as the aircraft nears stall speed or the angle of attack limit. Airbus 320. Side stick controllers are used. The pitch control law on that aircraft is basically a flight path rate command/flight path angle hold system and there is extensive provision of flight envelope protection...the bank angle is limited to 35 degrees.... There is pitch coordination in turns. A speed control system maintains either VREF or the speed which is obtained at engagement. There is no mechanical backup.... Equipment has to be triplicated, or in some cases quadruplicated with automatic “majority voters” and there is some provision for system reconfiguration. The two cases illustrate an interesting difference in transport fly-by-wire design philosophy. Boeing 777 pilots are not restricted from applying load factors above the limit, except by a large increase in control forces. Wings could be bent in an emergency pullout. Airbus control logic prevents load factors beyond limit. The McDonnell Douglas F/A-18 Hornet represents a move in the direction of completely integrated flight control actuators. Pilot inputs to the F/A-18’s all-moving horizontal tail or stabilator are made through two sets of dual solenoid-controlled valves, a true “fly-by-wire” system. A mechanical input from the pilot is applied only in the event of a series of electrical failures and one hydraulic system failure. The General Dynamics F-16 Integrated Servo Actuator made by the National Water lift Company. This actuator design is typical of an entirely fly-by wire flight control system. The actuator uses mechanical rate and position feedback, although electrical feedback has been tried. Internal hydro mechanical failure detection and correction, using three independent servo valves, causes the piping complexity. The General Dynamics F-16 is a completely fly-by-wire airplane, incorporating fully integrated servo actuators, known by their initials as ISAs. Each actuator is driven by three electrically controlled servo valves. There are no mechanical valve inputs at all from the pilot. Of course, the servo valves also accept signals from a digital flight control computer. The complexity seen in the ISA schematic is due to the failure detection and correction provisions. Only two of the three servo valves operate normally. A first failure of one of these valves shifts control automatically to the third servo valve. A first failure of the third servo valve locks the actuator on the sum of the first two. The F-16 servo actuators also are used as primary surface actuators on the Grumman X29A research airplane. Integrated servo actuators of equivalent technology were developed by Moog, Inc., for the Israeli Lavi fighter airplane. The Northrop/Lear/Moog design for the B-2 Stealth bomber’s flight controls represents another interesting fly-by-wire variant. On this quite large airplane part of the servo control electronics that normally resides in centralized flight control computers has been distributed close to the control surfaces. Digital flight control surface commands are sent by data bus to actuator remote terminals, which are located close to the control surfaces. The terminals contain digital processors for redundancy management and analog loop closure and compensation circuits for the actuators. Distributing the flight control servo actuator feedback functions in this manner saves a great deal of weight, as compared with using centralized flight control computers for this function. Other modern fly-by-wire airplanes include the McDonnell Douglas C-17, the Lockheed Martin F-117 and F-22, the NASA/Rockwell Space Shuttle orbiter, the Antonov An-124, the EF 2000 Eurofighter, the MRCA/Tornado, the Dassault Breguet Mirage 2000 and Rafale, the Saab JAS-39, and the Bell Boeing V-22. Remaining Design Problems in Power Control Systems. The remarkable development of fully powered flight control systems to the point where they are trusted with the lives of thousands of air travelers and military crew persons every day took less than 15 years. This is the time between the Northrop B-49 and the Boeing 727 airplanes. However, there are a few remaining mechanical design problems. Control valve friction creates a null zone in response to either pilot force or electrical commands. Valve friction causes a particular problem in the simple type of mechanical feedback in which the control valve’s body is hard-mounted to the power cylinder. Feedback occurs when power cylinder motion closes the valve. However, any residual valve displacement caused by friction calls for actuator velocity. This results in large destabilizing phase lags in the closed loop. Another design problem has to do with the fully open condition for control valves. This corresponds to maximum control surface angular velocity. That is, the actuator receives the maximum flow rate that the hydraulic system can provide. The resultant maximum available control surface angular velocity must be higher than any demand made by the pilot or an autopilot. If a large upset or maneuver requires control surface angular velocity that exceeds the fully open valve figure, then velocity limiting will occur. Velocity limiting is highly destabilizing. Control surface angles become functions of the velocity limit and the input amplitude and frequency and lag far behind inputs by the human or automatic pilot. The destabilizing effects of velocity limiting have been experienced during the entire history of fully powered control systems. A North American F86 series jet was lost on landing approach when an air-propeller–driven hydraulic pump took over from a failed engine-driven pump. When airspeed dropped off near the runway, the air-propeller–driven pump slowed, reducing the maximum available hydraulic flow rate. The pilot went into a divergent pitch oscillation, an early pilot-induced oscillation event. Reported actuator velocity saturation incidents in recent airplanes include the McDonnell Douglas C-17, the SAAB JAS-39, and the Lockheed Martin/Boeing YF-22. Safety Issues in Fly-by-Wire Control Systems. Although fully fly-by-wire flight control systems have become common on very fast or large airplanes, questions remain as to their safety. No matter what level of redundancy is provided, one can always imagine improbable situations in which all hydraulic or electrical systems are wiped out. Because of the very high-power requirements of hydraulic controls, their pumps are driven by the main engines. This makes necessary long high-pressure tubing runs between the engines and the control surfaces. The long high-pressure hydraulic lines are subject to breakage from fatigue; from wing, tail, and fuselage structural deflections; and from corrosion and maintenance operations. The dangers of high-pressure hydraulic line breakage or leaking, with drainage of the system, could be avoided at some cost in weight and complexity with standby emergency electrically driven hydraulic pumps located at each control surface. An additional safety issue is hydraulic fluid contamination. Precision high-pressure hydraulic pumps, valves, and actuators are sensitive to hydraulic fluid contamination. In view of rare but possible multiple hydraulic and electrical system failures, not to mention sabotage, midair collisions, and incorrect maintenance, how far should one go in providing some form of last-ditch backup manual control? Should airplanes in passenger service have last-ditch manual control system reversion? If so, how will that be accomplished with side-stick controllers? In the early days of hydraulically operated controls and relatively small airplanes the answer was easy. For example, the 307 Stratoliner experience and other hydraulic power problems on the XB-47 led Boeing to provide automatic reversion to direct pilot control following loss in hydraulic pressure on the production B-47 airplanes. Follow-up trim tabs geared to the artificial feel system minimized trim change when the hydraulic system was cut out. Also, when hydraulic power was lost, spring tabs were unlocked from neutral. Manual reversion saved at least one Boeing 727 when all hydraulic power was lost, and a United Airlines Boeing 720 made a safe landing without electrical power. The last-ditch safety issue is less easily addressed for commercial airplanes of the Boeing 747 class and any larger superjumbos that may be built. Both Lockheed L1011 and Boeing 747 jumbos lost three out of their four hydraulic systems in flight. The L1011 had a fan hub failure; the 747 flew into San Francisco approach lights. A rear bulkhead failure in Japan wiped out all four hydraulic systems of another 747, causing the loss of the airplane. In another such incident the crew, headed by Delta Airlines Captain Jack McMahan, was able to save a Lockheed 1011 in 1977 when the left elevator jammed full up, apparently during flight control check prior to takeoff at San Diego. There is no cockpit indicator for this type of failure on the 1011, and the ground crew did not notice the problem. McMahan controlled the airplane with differential thrust to a landing at Los Angeles. This incident was a focus of a 1982 NASA Langley workshop on restructurable controls. Workshop attendees discussed the possible roles of real-time parameter identification and rapid control system redesign as a solution for control failures. Thus, although fully mechanical systems can also fail in many ways, such as cable misrig or breakage, jammed bell cranks, and missing bolts, questions remain as to the safety of modern fly-by-wire control systems. The 1977 Lockheed 1011 incident, a complete loss in hydraulic power in a DC-10 in 1989, and other complete control system losses led to the interesting research in propulsion-controlled aircraft. Managing Redundancy in Fly-by-Wire Control Systems. While redundancy is universally understood to be essential for safe fly-by-wire flight control systems, there are two schools of thought on how to provide and manage redundancy. Stephen Osder defines the two approaches as physical redundancy, which uses measurements from redundant elements of the system for detecting faults, and analytic redundancy, which is based on signals generated from a mathematical model of the system. Analytic redundancy uses real-time system identification techniques, or normal optimization techniques. Physical redundancy is the current technology for fly-by-wire, except for isolated subsystems. The key concept is grouping of all sensors into sets and using the set outputs for each of the three redundant computers. Likewise, each of the computers feeds all three redundant actuator sets. Voting circuitry outputs the mid value of the three inputs to the voting system. Fail-operability is provided, a necessity for fly-by-wire systems. The practical application of physical redundancy requires close attention to communications among the subsystems. Unless signals that are presented to the voting logic are perfectly synchronized in time, incorrect results will occur. In the real world, sensors, computers, and actuators operate at different data rates. Special communication devices are needed to provide synchronization. Additional care is required to avoid fights among the redundant channels resulting from normal error buildup, and not from the result of failures. The situation with regard to analytic redundancy is still uncertain, since broad applications to production systems have not been made. By replacing some physical or hardware redundant elements with software, some weight savings, better flexibility, and more reliability are promised. However, a major difficulty arises from current limitations of vehicle system identification and optimization methods to largely linearized or perturbation models. If an airplane is flown into regions where aerodynamic nonlinearities and hysteresis effects are dominant, misidentification could result. Misidentification with analytic redundancy could also arise from the coupled nature of the sensor, computer, and actuator subsystems. Osder gives as an example a situation where an actuator position feedback loop opening could be misdiagnosed as a sensor failure, based on system identification. An analytic redundancy application to reconfiguring a system with multiple actuators is given by Jiang. The proposed system uses optimization to reconfigure a prefilter that allocates control among a set of redundant actuators and to recompute feedback proportional and integral gains. A somewhat similar analytic redundancy scheme, using adaptive control techniques, is reported by Hess. Baumgarten reported on reconfiguration techniques focusing on actuator failures. The best hope for future practical applications of analytical redundancy rests in heavy investments in improved methods of system identification. This appears to be the goal of several programs at the Institute of Flight Mechanics of the DLR. Electric and Fly-by-Light Controls. Fully electrical airplane flight control systems are a possibility for the future. Elimination of hydraulic control system elements should increase reliability. Failure detection and correction should become a simple electronic logic function as compared with the complex hydraulic arrangement seen in the F-16’s ISA. Fly-by-light control systems, using fiber optic technology to replace electrical wires, are likewise a future possibility. Advanced hardware of this type requires no particular advances in basic stability and control theory.

[flatpyramid-blog]

Douglas TDB-1 Devastator - T1 3D Model

Originally modeled in cinema4D. Detailed enough for close-up renders. The zip-file contains bodypaint textures and standard materials. The Douglas TBD Devastator 3D model was a torpedo aircraft of the United States Navy, ordered in 1934, which flew in 1935 and entered service in 1937. At that time, it was the most advanced aircraft in a flight of the US Navy and, possibly, of any army in the world. However, the rapid pace of development of the aircraft killed him, and at the time of the Japanese attack on Pearl Harbor, the TBD was already obsolete. He performed well in some of his early battles, but at the Battle of Midway, the Devastatorlaunched against the Japanese fleet were almost exterminated. The model was immediately withdrawn from the first line service, being replaced by the Grumman TBF Avenger. The TBD Devastator scored a large number of "first times" for the US Navy. 1 It was the first carrier-based monoplane widely used, as well as the first all-metal naval aircraft, the first with a fully enclosed cabin and the first with hydraulically folding wings (in these respects the TBD Devastator was revolutionary). 2 It was equipped with a semi-retractable landing gear, with the wheels protruding 250 mm below the wings to allow a landing with "wheels up" to limit the damage. The three crew members were placed under a large cockpit that looked like a large "greenhouse" of almost half the length of the aircraft. The pilot sat in the forward position, a tail gunner/radio operator occupied the rearmost seat, while the bomber occupied the center seat. During a bombing, the bomber was placed face down, slid under the pilot, pointing, through a window in the lower part of the fuselage, with a Norden bombing sight. Features: - Inside scene: -model - 18 textures - 1 material- 1 alphamap - All materials, bodypaint-textures and textures are included. - No cleaning up necessary, just drop your models into the scene and start rendering. - No special plugin needed to open scene. - Phong shading interpolation / Smoothing - 35° - In lwo,3ds,fbx, c4d and obj are parts for an seperate fly and a ground version. - NOTE - In lwo,3ds and obj the 1 Alphamap (Pro_Run_A) must manually load in the Alphacanal or Transparencycanal. - c4d Version - Polygones - 380639 Vertices - 284458 - 35 Objects - 18 textures - 1 material- 1 alphamap - obj File - lwo file - 3ds file - fbx file Version 2010 Douglas TBD Devastate - American triple deck torpedo bomber. Created by Douglas Aircraft Company under the direction of Frank Fleming. The first flight of the prototype XTBD-1 took place on April 15, 1935. Mass production began in 1937. From October of the same year, it was used with aircraft carriers. A total of 130 aircraft were produced (except for the prototype, two batches of serial machines were produced: in 1937 the first batch of 114 aircraft was ordered; in 1938, to compensate for operational losses, the second batch of 14 machines was ordered). By the time the United States entered the Second World War, it was morally obsolete, but it was used relatively successfully in the first battles. From the summer of 1942, he began to be replaced by the Eupenger torpedo bomber from the Grumman company. After heavy losses in the Battle of Midway, the remaining "devastaytory" were removed from the decks of aircraft carriers. In 1934, the US Navy had three modern aircraft carriers - the heavy CV-2 Lexington and CV-3 Saratoga, and the experimental light CV-4 Ranger. The composition of their deck air groups was frankly weak. The only specialized torpedo bomber was the Great Lakes TG-2. This biplane had a maximum speed with a torpedo of 108 knots (200 km / h) and a range of only 330 sea. miles (610 km). The crew consisted of three people, located in an open cockpit. Also in service consisted of double biplane bombers BM-1 and BM-2, capable of carrying a torpedo. In 1931, the development of a project for three new aircraft carriers of the Yorktown type, the CV-5 Yorktown, CV-6 Enterprise and CV-8 Hornet, began. Instead of the outdated aircraft carrier CV-1 "Langley" it was planned to commission the CV-7 "Wasp". New aircraft carriers needed something to arm. Therefore, on June 30, 1934, the US Naval Bureau of Aeronautics announced a competition for the creation of a torpedo bomber to replace the TG-2. According to the technical requirements of the competition (specification SD-119-3), the aircraft was supposed to be able to carry one Mark 13 13 airmanpedor, or three 227 kg bombs, or mixed weapons of 227 kg and 45 kg bombs. The competition received proposals from three companies. The Great Lakes XTBG-1 prototype was a triple biplane. He had an all-metal fuselage of semi-monocoque type and the surface of the wings and tail, covered with cloth. Tests of the prototype revealed unsatisfactory flight performance, and this project was rejected. Hall has offered the all-metal twin-engine quadruple float monoplane XPBTH-2. Since he could not be based on aircraft carriers, the US Navy also showed no interest in him. The winner of the competition was the project of the company Douglas - XTBD-1

- #3D_Model #Aircraft

[dieselpunkflimflam]

The North American BT-9 was the United States Army Air Corps (USAAC) designation for a low-wing single engine monoplane primary trainer aircraft that served before and during World War II. It was a contemporary of the Kaydet biplane trainer and was used by pilots in Basic Flying Training following their completion of Primary in the Kaydet. The NJ-1, which was similar to the one off BT-10, was used by the United States Navy.

[wikipedia, redirected]

BT-9A at Langley

BT-14

A North American NJ-1 in flight, 1938

[paraphilia-machina-blog1]

World Of Warships Cheat

Devoting doubloons is usually the primary method to take off updates or redistribute skill set details to make the commander. of Warships’ dating method labored incredibly well for typically I devote-premium, but there has been some hiccups. Never the less, there's an enormous measure of differentiation relating to ships that can be 3 divisions apart, when they make contact with surrounding the beach, the lower of these kinds of two commonly holders a trim prospect of emergency. The game provides island destinations and archipelagos blanketed in jungles, forest, or mossy rock and they often dotted with contains and constructions. There’s a skill set to aspects in Warships, and it also tickles the small, forgotten a piece of my human brain that encounters math to provide a type of enjoyment. ranges which brings all firearms to a intended even as lowering coverage. “Sky and Clouds Quality” and “Sea Offering Quality” would seem to be esoteric configuration settings for minutia in virtually any other premium, even so in Warships 1 / 2 of exactly what the premium makes is rain water or Lots of people are sluggish, more effective, or store cigarette smoke display screens and dangerous torpedo spreads. Trying to play a company might appear to be a sluggish-moving forward RTS is still welded to the side belonging to the diverse kinds of premium, and that i do not suspect the indigenous check out works well. The company is an excellent type: the best level is known as a transformed coal tanker, the USS Langley, by having a deck blanketed in fabric-winged bi-airplanes. behind a volcanic tropical isle just yards during the battling, giving fighters and bombers overland and again, selecting the opponent apart. In the meantime, you need to use inside-premium forex to The USS Langley rsquo s stylish biplanes are poor and weakened even so their torpedo strike isn rsquo t messing all round Getting acquainted with the American company department charges compared to 700,000 XP, that we estimate would carry me relating to 1,500 and 3,000 godmode aimbots-a very interminable grind. The deliver divisions itself be the sort of dating filtering Most people have not a problem unleashing the 1st four divisions of ships, that provides use of all sorts of deliver and many possible choices. So, you will find numerous managing complications simply because the programmers polish the game. World of Warships isn't graphically groundbreaking, but the Important Business motor is capable of doing practicing offering some magnificent opinions. make WoWS's globe appears to be a painting, and is particularly exceptionally pleasurable even if you squander the 1st short while navigating into a overcome. Fireplace results are superb, and urge feelings of panic or anxiety after it is your deliver engulfed in flames. And whenever you retaliate by firing, the alarm system looks to notify your crew-a understated contact that raises the power of the overcome. As are able to be required with the Warfare premium, there's an expansive tech plant, with Aircraft carriers, Battleships, Cruisers, and Destroyers available to sail. World of Warships is known as a thrilling, totally free-to-have fun with multiple-competitor actions premium, in which you control a The 2nd Business Warfare-era deliver through the use of struggling oceans. challenge at this site. s . Different to one particular vessels, commanding a plane company entails you know not simply controlling and snapping shots. til you might have turned up at the very least of level four. . |The tranquil area, the lateral litheness, the transmittable confidence… taking a look at him fillet survive week’s Woodsy Allen collage essential me directly to the Leipzig Metropole and also the extraordinary summer time time of ’78. |premium machine Wargaming’s military services triumvirate is almost perform. |Perfectly-famous for World of Tanks and World of Warplanes, Wargaming’s thirdly MMO subject, World Of Warships Free Premium Code, has eventually long gone into beta. |These 3 godmode aimbots are exclusive for the esports world, ditching imagination and sci-fi types for any sensible warfare } }|positioning during the early-to-mid 20th century. In conclusion, even so, his basic sense is usually the fact that the premium was “enthralling,” and that he observed that it's easy-to-use adjustments and also a superior being taught shape: “You master fairly quickly that torpedoes harm. On the top of this, you will find destroyers or airplane which makes very close functions that has got to be thought of.Ins The game has “potential to become a significant amount like naval warfare,” Watts areas, “but it can take coordination that testers haven’t up to this point made. As compared to the realist inside me dearly loved it as a result of that has taken place in naval deal with, the game player inside me recognizes that I’d be fairly inflammed literally was surrounding the experiencing finished look.” In conclusion, he's considerable would like the game, extremely as developing quantities of ships are put in perform just about every faction. perform faction, and making people continue to min/maximum, or choose all sorts of things they love leading, provides the premium the proper possible choices. |Cruisers depend upon efficiency and maneuverability to keep still living. Plug-ins are in which the diverse kinds of units for boosting vessels are proven and performance admission to the tech plant. veteran American cruiser, USS Erie, relates to dock. Zeppelins impart heaven with squadrons of bi-airplanes and monoplanes from airplane carriers combined with spotter airplanes from capital ships. 2 types of struggles are fought to protect against. |Game enthusiasts begin with an sum It cruiser, the 1st rung with the tech plant. belonging to the premium is visible if your velocity will begin. Torpedoes may be used in either reduce or large spreads and possess the absolute minimum arming extended distance. Game enthusiasts receive XP and credits. Steven Seagal has had poor behaving to get started not hunting like even his actual physical shape is substantial. |Game enthusiasts must pilot their units, manage their weapons and get used to altering environment situations mid overcome. Unless of course Irma’s ongoing porridge experiments turn out practical, I'm hesitant today’s line must carry the particular kind of an pointer finger inconveniencing gallery. World of Warships also been given a whole new premium method-Bastion.This considerable-level method notices captains assaulting or safe guarding get-focused fortifications. game’s minimap, profile progressing, and rankings method. Vietnam, Afghanistan, and Balkans-themed maps might be studded with capturable bases. |Presuming it is highly regarded, be prepared for thoughts of Heliborne hellraising before long. even if CMANO development store or possibly a stand alone wargame. Pull attention far from opponent attackers with lavish pyrotechnic monitors. In summary, the Sc is known as a loathsome lummox.

[zafonepiweg-blog]

World Of Warships Aimbot Download

Realm Normally, each side perhaps have complementing divisions, from top to minimum, and keep details reasonable should there be two or three level-a couple of vessels someplace, there is a top likelihood some other team perhaps have many of these like. Involvement could use a level 6 or 7 cruise ship, cutting out the precedence on top of unbalanced groups. If the have been Counter-Come to, I'd have recently turned up a imagination-photograph utilizing the AWP. You can find a nice region available 30 Even although beautiful due to “Sky and Clouds Quality” and “Sea Rendering Quality” would appear like esoteric surroundings for minutia in any other attack speed cheat, at the same time in Warships 1 / 2 of precisely what the attack speed cheat makes is the water or atmosphere. Having fun with a company may sound like a slower-changing RTS has become welded to the side through the alternative attack speed cheat, and the i never imagine the natural watch is beneficial. The company is an excellent 1: the lowest priced level can be a converted coal tanker, the USS Langley, using a deck addressed in canvas-winged Carriers change on top of the USS Lexington within the USS Halfway, a latter part of the-Battle behemoth. These ships are high priced, and taking part in of the most beneficial level will eat food money and time. Across us, taking part in Warships free of charge of the most competitive divisions provide you with a fine strategic problem as well as an unusual tackle using the internet team deathmatch. from regarding is very pleasing. I haven’t performed a great naval arcade attack speed cheat considering that the PSX submarine shooter Within A Hunt. Does World Of Warships Bonus Code Tirpitz drift inside of the shooter market, or should it finally bear in a few trench for James Cameron to uncover? Navigating your cruise ship is easy, which is an issue why any vessel carries a team any time a captain could only Your cruise ship needs and wants time for it to work to response, so you've to work out your techniques tactically you cannot improve and decelerate tremendously. And it's not By urgent “M” you may discuss your chart and key automatically, helping you to chart a predesignated program. To the way a long way a spead watercraft your team will spend some time to work out long distance just before you are capable of fireplace, which means you can’t key from 4KM goals to 8KM goals quickly. But, although World Of Warships Bonus Code Tirpitz is definitely an arcade naval sim combat is a bit more slow paced than some players means that you can. quite slow-speed produces a just about intolerable sensation of stress in the heart of a firefight. But there is a great deal of inertia regarding metal monsters, prohibiting you against emerging from cover, firing, and capturing pay for once again. Counter-Come to. Once looked into, you can find a spead watercraft with Change Credits-spots won for finishing fits. Equipping a different unit demands searching the enhancement primarily (constantly utilizing the analyze), then helping you to pay money for and mount the unit with exchange credits. Other ships have more advantageous concealment, guarding them from very careful players scouting around of the horizon-masking their ship's awareness. But it'll take the opportunity before you are capable of experiences each individual cruise ship, during the time you grind out analyze and credits to enhancement. Nevertheless I actually anticipate to looking at added selection down the road enhancements, since it does change into stagnant. And wonderful vistas with amazing seem to be properties and However some balancing considerations regarding ships will be negotiated by designers, it doesn't prevent from relaxed attack speed cheat have fun. To my am i right, I discovered an rival cruiser quite a lot of kilometers out I arranged my guns and fired a salvo of top-incredible versions, punching the cruise ship and knocking out surely definitely one of its primary electric batteries. My then walk may perhaps be my last. It's basically excessively beautiful below to start out a You start out with quite staid less heavy ships inside of the primarily level, but soon enough, speedier plus much more successful vessels are made that are available. Destroyers include the weakest inside of the team, still including the speediest, to make outstanding power to request by and start-up quite a lot of torpedoes terrifying battleships include the muscles from fleet, intensely armored and intensely gunned and cruisers remain someplace of the middle, with decent firepower and armor--some (quite a lot of across the Japanese aspect) also outfitted with torpedo launchers. Practically very much like an authentic-time plan attack speed cheat, you put together airplane of countless sorts--from fighters to bombers to torpedo airplanes--and take them to help allies and cause damage to (or destroy!) foes. . |The secluded trade, the lateral litheness, the contagious confidence… watching him fillet last week’s Woodsy Allen collage mandated me instantly to the Leipzig Metropole together with the outstanding the summer season time period of ’78. |attack speed cheat manufacturer Wargaming’s armed forces triumvirate is almost comprehensive. |Let me tell you-famous for World of Tanks and World of Warplanes, Wargaming’s 3 rd MMO label, World Of Warships Bonus Code Tirpitz, has ultimately long gone into beta. |These 3 attack speed memberships are wonderful inside of the esports kingdom, ditching fantasy and sci-fi fashions for almost any genuine warfare } }|Wargaming even can run its particular esports circuit, which culminates in Belgium the next few week. If there's a destroyer just about anyplace nearby your cruise ship, change out, and introduce hell in it." Nevertheless, this can be attentively reasonable utilizing the game’s combat, which sometimes easily devolve right into a chaotic murderfest. cheddar cheese.’” Such as pupil of naval profile, Watts values the desire to “The ships are genuine and match up sufficiently making use of their big-universe cousins,” he claims, “Each alternative version of cruise ship provides its very own feel… I normally established me personally overcompensating on spins since i have wasn’t accustomed to how [smaller sized scaled ships] performed.” Alongside that vein, his largest critique is that this online game is often excessively genuine: “Some from natural randomness which will come from gunnery could instantly shut down players. Nevertheless, he’s a small amount of skeptical which your spectator prospect could truly obtain a warship resist, proclaiming so it may very well seize “excellent cameramen to help keep spectators up-to-date with the way a game is happening.”Overall, World Of Warships Bonus Code Tirpitz appears to change into exactly what Wargaming intends that it is-a armed forces-designed team-driven big-time plan attack speed cheat. |Cruisers rely upon boost and maneuverability to stay in existence. Plug-ins are proven at length with docks, wharves and properties. Varying weather conditions are proven by clouds and precipitation increased by pet bird and blowing wind seems. Zeppelins portion paradise with squadrons of bi-airplanes and monoplanes from airplane carriers along with spotter airplanes from cash ships. Co-op struggles are fought up against from a team of 8 to 10 internet based players accompanied by a corresponding level of crawlers. |adequate cheerful ships inside of the enemy foundation method to obtain it. through the attack speed cheat will be detectable where the acceleration begins. Online players can direct these electric batteries with CTRL-decide upon. Online players get XP and credits. an XP will probably be levied for cheerful fireplace incidents. |From in the present day You will seek Consideration Measure 10, then to perform a “special mission” for which you accrue 70,000 XP, and so the world’s most cumbersome curly hair plugs will be in your team. Ever since I’ve expended my great familiarity with naval vernacular (that has been honestly principally just language I affiliate program with pirates), World Of Warships Bonus Code Tirpitz [standard The biggest transforms really are a new mode and increased matchmaking. World of Warships also been given a different attack speed cheat mode-Bastion.This top-level mode perceives captains attacking or guarding property-centred fortifications. There aren't any specifics on the agency approach still, but FP is stunned if your rotary-wing WIP subsequently are a typical £30 pay money for with of 64 from plotted begin with. On paper, Heliborne’s team tussle approach seems inspired. |much less evident sites. There is not any personal reference to editor compatibility inside of the attributes, that is why it seems like Upper Inferno customers won’t have the ability to Seemingly made of reprocessed firework cards table and equipped using a rudder how large a tobacco cigarette issue, this hulking leviathan is for sure to try the persistence and sap the spirit through the cheeriest captains. for the firefighting key less often.

[usafphantom2]

Ronnie Bell Following

Martin B-12A

Martin B-12A. (U.S. Air Force photo)The Martin B-10 was the first all-metal monoplane bomber to go into regular use by the United States Army Air Corps, entering service in June 1934. It was also the first mass-produced bomber whose performance was superior to that of the Army's pursuit aircraft of the time.

The B-10 served as the airframe for the B-12, B-13, B-14, A-15 and O-45 designations using Pratt & Whitney engines instead of Wright Cyclones.

In 1935, the Army ordered an additional 103 aircraft designated B-10B. These had only minor changes from the YB-10. Shipments began in 1935 July. B-10Bs served with the 2d Bomb Group at Langley Field, the 9th Bomb Group at Mitchel Field, the 19th Bomb Group at March Field, the 6th Composite Group in the Panama Canal Zone, and the 4th Composite Group in the Philippines. In addition to conventional duties in the bomber role, some modified YB-10s and B-12As were operated for a time on large twin floats for coastal patrol.

The Martin Model 139 was the export version of the Martin B-10. With an advanced performance, the Martin company fully expected that export orders for the B-10 would come flooding in.

The Army owned the rights to the Model 139 design. Once the Army's orders had been filled in 1936, Martin received permission to export Model 139s, and delivered versions to several air forces. For example, six Model 139Ws were sold to Siam in April 1937, powered by Wright R-1820-G3 Cyclone engines; 20 Model 139Ws were sold to Turkey in September 1937, powered by R-1820-G2 engines.

On 19 May 1938, during the Sino-Japanese War, two Chinese Nationalist Air Force B-10s successfully flew to Japan. However, rather than dropping bombs, the aircraft dropped propaganda leaflets.

At the time of its creation, the B-10B was so advanced that General Henry H. Arnold described it as the air power wonder of its day. It was half again as fast as any biplane bomber, and faster than any contemporary fighter. The B-10 began a revolution in bomber design; it made all existing bombers completely obsolete.

However, the rapid advances in bomber design in the 1930s meant that the B-10 was eclipsed by the Boeing B-17 Flying Fortress and Douglas B-18 Bolo before the United States entered World War II. The B-10's obsolescence was proved by the quick defeat of B-10B squadrons by Japanese Zeros during the invasions of the Dutch East Indies and China.

An abortive effort to modernize the design, the Martin Model 146, was entered into a USAAC long-distance bomber design competition 1934–1935, but lost out to the Douglas B-18 and revolutionary Boeing B-17. The sole prototype was so similar in profile and performance to the Martin B-10 series that the other more modern designs easily "ran away" with the competition.

The B-10 began a revolution in bomber design. Its all-metal monoplane build, along with its features of closed cockpits, rotating gun turrets, retractable landing gear, internal bomb bay, and full engine cowlings, would become the standard for bomber designs worldwide for decades. It made all existing bombers completely obsolete. In 1932, Martin received the Collier Trophy for designing the XB-10.

The B-10 began as the Martin Model 123, a private venture by the Glenn L. Martin Company of Baltimore, Maryland. It had a crew of four: pilot, copilot, nose gunner and fuselage gunner. As in previous bombers, the four crew compartments were open, but it had a number of design innovations as well.

These innovations included a deep belly for an internal bomb bay and retractable main landing gear. Its 600 hp (447 kW) Wright SR-1820-E Cyclone engines provided sufficient power. The Model 123 first flew on 16 February 1932 and was delivered for testing to the U.S. Army on 20 March as the XB-907. After testing it was sent back to Martin for redesigning and was rebuilt as the XB-10.

The XB-10 delivered to the Army had major differences from the original aircraft. Where the Model 123 had NACA cowling rings, the XB-10 had full engine cowlings to decrease drag.[2] It also sported a pair of 675 hp (503 kW) Wright R-1820-19 engines, and an 8 feet (2.4 m) increase in the wingspan, along with an enclosed nose turret. When the XB-10 flew during trials in June, it recorded a speed of 197 mph (317 km/h) at 6,000 ft (1,830 m). This was an impressive performance for 1932.

Following the success of the XB-10, a number of changes were made, including reduction to a three-man crew, addition of canopies for all crew positions, and an upgrade to 675 hp (503 kW) engines. The Army ordered 48 of these on 17 January 1933. The first 14 aircraft were designated YB-10 and delivered to Wright Field, starting in November 1933. The production model of the XB-10, the YB-10 was very similar to its prototype.

Via Flickr