#dihedral

[luispablocarmonaenjolras]

GÉNESIS UNIVERSO DIÉDRICO

[july-19th-club]

just remembered that when i first got really into turkey vultures i learned about airplanes bc i had to go look up 'dihedral' because the turkey vulture is one of the best soaring birds we have in my area and it's because of not just their wing shape, which is both more tapered toward the tips AND more spread out, excellent for taking advantage of wind currents and, say it with me everyone, thermals but because of their dihedral, which is the upward angle at which the wings sit, which allows them to soar without expending much energy for such long periods of time anway i quickly forgot all about how dihedral works on airplanes because i was too busy with my best friend cathartes aura aura anyway who wants to talk abt the noble turkey buzzard im simply dying to talk abt the noble turkey buzzard

[thedaily-beer]

Grimm Dihedral Synchro-Helix Actuation Door Double IPA (Picked up at Whole Foods in Plymouth Meeting, PA). A 4 of 4. The addition of phantasm takes this over the top -- tons of bright tropical fruit and white wine notes as well as quite a bit of citrus and stone fruit behind it. Just incredibly pungent. The body is nicely balanced with some fruity sweetness up front behind the hop profile and a dry and clean finish that's bitter, but not overly aggressive.

[some-teeth-in-a-trench-coat]

Is there a way to derive the dihedral angle of a regular polyhedron using only the Schläfli symbol without just looking it up how do you figure out anything about a spherical regular polygon with n vertices without knowing the angles only the sides am I just trying to do the impossible or are the articles I find just misleadingly short

[er-cryptid]

[itsanautiething]

I don't know why I find this so funny, but I think it's fricken hilarious and therefore must share.

[animal-forgeries]

today's mimic: zone-tailed hawk, buteo albonotatus

the zone-tailed hawk has been suggested to mimic turkey vultures, most obviously in their flight pattern: the hawks fly unusually with wings raised dihedrally, and will rock back and forth in a similar manner to turkey vultures. additionally, the silhouette and the shape of the flight feathers resemble a turkey vulture much more than other similar hawks. this is an example of aggressive mimicry, since turkey vultures rarely hunt animals, while the zone-tailed hawk is an active predator. its prey will be more likely to ignore the presence of the bird, believing it to be a harmless scavenger. the kettling behaviour of turkey vultures aids the zone-tailed hawk, as it can blend into large gatherings of vultures. although up close the two animals are very different, even experienced birders may have difficulty identifying a zone-tailed hawk from its deceitful silhouette and flight pattern.

model:

photo by roy lowe

flight pattern comparison:

[msexcelfractal]

steven wolfram generated sierpinski's gasket with a cellular automaton. the rule of action for this automaton is logical xor. I notice loxigal xor is equivalent to addition modulo 2. I make a bunch of art, mostly in addition modulo 2 or 3.

I think to myself, modular addition is the operation of cyclic groups. Why restrict myself to cyclic groups? why restrict myself to abelian groups even? Just because Excel's architecture assumes cell contents are real numbers? Pah. I write a formula to iterate wolfram's sierpinski rule using arbitrarily defined group operation. B11=INDIRECT(ADDRESS(A11+3,B10+3)). This will compute B11 as group operation A11⊕B10, where ⊕ is designated by the cayley table whose upper left corner is C3. Since B10 is above B11 and A10 is to B11's left, the pattern formed by ⊕ cascades down and to the right.

Here's a sierpinski gasket "modulo" [the dihedral group of order 6]. The group D6 is generated by the actions of [horizontal reflection] and [120° rotation] on a plane.

[lambergeier]

climbing blogging: flashed another 11a (worrying. means i have to start trying 11b's now) but also got hard blocked on two 10d's and for sure pulled some shit in my hip and shoulder trying to push up on a dihedral. we stay stretching boys

[locally-normal]

Don't worry, if you spend a while considering a space with a group action up to homotopy you can conclude that no one really understands group actions.

Seeing that the Weyl group W_G(H) := normalizer of H in G / H is the set of equivariant (ie group action preserving) maps from G/H to G/H is pretty neat though, would recommend, it's a fun exercise. G/H here is the set of H cosets of G, with a G action given by g . H = gH. (Remember that for G/H to be a group H must be normal, but you can always write a set of cosets G/H).

I did that one a while ago and then recently had to remind myself and do it for the case G=O(2) and H=Z/2 generated by a map with determinant -1, ie a flip. Good stuff.

Finally understanding group actions and all it took was looking at this picture (from Michael Artin’s Algebra)

[captain-price-unofficially]

An old straight-dihedral B-25 contrasts with the crank-winged Mitchells behind it at Felts Field, Spokane, Washington. 1941

[usafphantom2]

OTD in 1969, The Iconic XB-70 Valkyrie Mach 3 Super Bomber Made Its Last Flight

February 4, 2021 Military Aviation, Military History

Three drag chutes were needed to slow down the landing roll of the XB-70. (Image credit: Reddit edit The Aviationist)

The massive XB-70 Valkyrie is the largest and heaviest airplane ever to fly at Mach 3.

The North American XB-70 Valkyrie was the most ambitious super-bomber project of the Cold War. The massive six-engine bomber was slated to be the ultimate American high-altitude, high-speed, deep-penetration manned nuclear bomber designed to fly high and fast, so as to be safe from Soviet interceptors.

Two Valkyrie prototypes were been built at North American Aviation before the Kennedy Administration cancelled the program as a consequence of the doubts that surrounded the future of manned bombers believed to be obsolete platforms. The threat posed by Soviet SAMs (Surface-to-Air Missiles) put the near-invulnerability of the strategic bomber at high altitudes in doubt. In low-level penetration role, the B-70 offered little performance improvement over the B-52 it was designed to replace (!) and it was much more expensive with shorter range.

Some fascinating variants of the aircraft were proposed. Some envisaged the B-70 carrying an Alert Pod, or flying as a Supersonic Refueler or as a Recoverable Booster Space System (RBSS). You can find all the details about these crazy concepts in this story we have posted last year.

Ezoic

The B-70 program was canceled in 1961 and development continued as part of a research program to study the effects of long-duration high-speed flight with the two XB-70A.

XB-70A number 1 (62-001) made its first flight from Palmdale to Edwards Air Force Base, CA, on Sept. 21, 1964. The second XB-70A (62-207) made its first flight on Jul. 17, 1965. The latter differed from the first prototype for being built with an added 5 degrees of dihedral on the wings as suggested by the NASA Ames Research Center, Moffett Field, CA, wind-tunnel studies.

While the 62-001 made only one flight above Mach 3, because of poor directional stability experienced past Mach 2.5, the second XB-70, achieved Mach 3 for the first time on Jan. 3, 1966 and successfully completed a total of nine Mach 3 flights by June on the same year.

Photo of the XB-70 #1 cockpit, which shows the complexity of this mid-1960s research aircraft. On the left and right sides of the picture are the pilot’s and co-pilot’s control yokes. Forward of these, on the cockpit floor, are the rudder pedals with the NAA North American Aviation trademark. Between them is the center console. Visible are the six throttles for the XB-70’s jet engines. Above this is the center instrument panel. The bottom panel has the wing tip fold, landing gear, and flap controls, as well as the hydraulic pressure gages. In the center are three rows of engine gages. The top row are tachometers, the second are exhaust temperature gages, and the bottom row are exhaust nozzle position indicators. Above these are the engine fire and engine brake switches. The instrument panels for the pilot left and co-pilot right differ somewhat. Both crewmen have an airspeed/Mach indicator, and altitude/vertical velocity indicator, an artificial horizon, and a heading indicator/compass directly in front of them. The pilot’s flight instruments, from top to bottom, are total heat gage and crew warning lights; stand-by flight instruments side-slip, artificial horizon, and altitude; the engine vibration indicators; cabin altitude, ammonia, and water quantity gages, the electronic compartment air temperature gage, and the liquid oxygen quantity gage. At the bottom are the switches for the flight displays and environmental controls. On the co-pilot’s panel, the top three rows are for the engine inlet controls. Below this is the fuel tank sequence indicator, which shows the amount of fuel in each tank. The bottom row consists of the fuel pump switches, which were used to shift fuel to maintain the proper center of gravity. Just to the right are the indicators for the total fuel top and the individual tanks bottom. Visible on the right edge of the photo are the refueling valves, while above these are switches for the flight data recording instruments. (Image credit: NASA)

A joint agreement signed between NASA and the Air Force planned to use the second XB-70A prototype for high-speed research flights in support of the American supersonic transport (SST) program.

However, on June 8, 1966, the XB-70 62-207 was involved in one of the most famous and tragic accidents in military aviation when it collided with a civilian registered F-104N while flying in formation as part of a General Electric company publicity photo shoot over Barstow, California, outside the Edwards Air Force Base test range in the Mojave Desert. The aircraft were flying in formation with a T-38 Talon, an F-4B Phantom II, and a YF-5A Freedom Fighter.

North American XB-70A Valkyrie just after collision. Note the F-104 is at the forward edge of the fireball and most of both XB-70A vertical stabilizers are gone. (U.S. Air Force photo)

As explained in a previous post here at The Aviationist:

Towards the end of the photo shooting NASA registered F-104N Starfighter, piloted by famous test pilot Joe Walker, got too close to the right wing of the XB-70, collided, sheared off the twin vertical stabilizers of the big XB-70 and exploded as it cartwheeled behind the Valkyrie. North American test pilot Al White ejected from the XB-70 in his escape capsule, but received serious injuries in the process. Co-pilot Maj. Carl Cross, who was making his first flight in the XB-70, was unable to eject and died in the crash.

The root cause of the incident was found to be wake turbulence: wake vortices spinning off the XB-70’s wingtip caused Walker’s F-104N to roll, colliding with the right wingtip of the huge XB-70 and breaking apart. As explained in details in this post, wingtip vortices form because of the difference in pressure between the upper and lower surfaces of a wing. When the air leaves the trailing edge of the wing, the air stream from the upper surface is inclined to that from the lower surface, and helical paths, or vortices, result. The vortex is strongest at the tips and decreasing rapidly to zero nearing midspan: at a short distance from the trailing edge downstream, the vortices roll up and combine into two distinct cylindrical vortices that constitute the “tip vortices.

Although research activities continued with the first prototype with a first NASA flight on April 25, 1967, the last one was on Feb. 4, 1969.

The only remaining XB-70 Valkyrie super bomber in on display at the National Museum of the U.S. Air Force at Wright-Patterson AFB in Dayton, Ohio. In October last year, it had to briefly moved outside for display maintenance. Here you can watch a video of the monumental move.

A view of the six massive afterburners on the XB-70 Valkyrie as the aircraft is towed out of its display hangar temporarily for museum maintenance. (Photo: National Museum of the U.S. Air Force via YouTube)

About David Cenciotti

David Cenciotti is a journalist based in Rome, Italy. He is the Founder and Editor of “The Aviationist”, one of the world’s most famous and read military aviation blogs. Since 1996, he has written for major worldwide magazines, including Air Forces Monthly, Combat Aircraft, and many others, covering aviation, defense, war, industry, intelligence, crime and cyberwar. He has reported from the U.S., Europe, Australia and Syria, and flown several combat planes with different air forces. He is a former 2nd Lt. of the Italian Air Force, a private pilot and a graduate in Computer Engineering. He has written five books and contributed to many more ones.

@TheAviationist via X

[jomindraws]

Fifth Phylum !!111! Opposed Elasmochordata STILL in Superphylum Near Bilateral !!

PHYLUM OPPOSED ELASMOCHORDATA

Phylum containing a bidirectional, plated, segmented nerve column and an exoskeleton of calcium carbonate.

(AN1 A2-c) Clade: Chamatae

A clade of opposed elasmochordates that contain a calcium carbonate shell, respirate with an active muscle valve, and locomote via ciliary or muscular valve locomotion.

Class Opposed Clamoids

Class of chamatae that consume organisms through a baleen-analagous filter located on one of the valve ends of the opposition.

Class Dihedral Mollusks

Class of chamatae that consume organisms with an extending tooth-barbed muscle located on one of the valve ends of the opposition.

(AN1 A2-d) Clade: Findopseudopescadae

A clade of opposed elasmochordates that contain an enamel shell, an interior support structure of hyaline cartilage, respirate with pseudo-gill structures, and locomote via water jet excretion or rotation.

Class Walking Steeples

Class of findopseudopescadae that have a semi-flexible exoskeleton, 3-4 long and rigid appendages, a central dorsal node head lined with sensing pili, and are completely benthic.

Class Bifin Aquatics

Class of findopseudopescadae that have a flexible outer shell, 2 ends ending in forked or lunate fins, and use labriform locomotion to swim in pelagic environments.

You may have noticed two things with these guys ! First of all, they are split down the middle! The head end of the nerve column ends at two tails ends as opposed to one. This allows for both enhanced growth and sensing, a splitting and managing of different tasks (most observable on the opposed clamoids and dihedral mollusks) and also redundancy in the event of a predator attack! These guys are also "elasmochordata", which means their nerve chord is segmented into many plates that can be bent and stretched, acting as both a "spine" and a "nerve cord" that can be separated into different functions (similar to how each vertebrae of a mammal can control different body systems)

The second thing you may have noticed is that there are quite a lot of phyla ending in "cord" or "chordata", while on Earth Chordates are just ONE phylum. Well, on Jom'Gol, these different creatures have had a longer period of time to differentiate and speciate-- they are already distinct enough on phylogenetic records. However, the physical differences are very unique as well ! Each type of "nerve cord" has a different time, material, shape, growing structure, and placement that it develops in during the embryo-- and although some creatures may look similar, even an inspection of the spinal cord both during adulthood will show wildly different shapes between phyla!

[legosaurus]

McLaren & Lego Unveil Lego Technic McLaren P1

The British supercar maker McLaren Automotive and the Lego Group today unveil their latest collaboration paying tribute to the world’s most pioneering hybrid hypercar, with the introduction of the Lego Technic McLaren P1.

The McLaren P1 redefined automotive high-performance as the most exciting, most capable, most technologically advanced and most dynamically accomplished supercar of its time. The P1 leveraged McLaren’s advanced motorsport-based engineering, featuring ground-breaking advances in weight reduction, packaging, high-speed performance, powertrain and aerodynamics.

Created with the intention of being ‘the best driver’s car in the world on both road and track’, the design and technical specifications of the McLaren P1 provided the ideal foundation to deliver on this ambition. The remarkable hypercar is recognized as a landmark both for McLaren and the development of high-performance hybrid vehicles.

The incredible engineering and technology underpinning the performance, style and functional design the McLaren P1, made it the perfect challenge for the Lego Technic team to replicate in 1:8 scale.

Unveiled as part of the Lego Technic Ultimate Car Concept Series, the all-new 1:8 scale Lego Technic version consists of 3,893 elements and each car features a unique serial number which unlocks special behind-the-scenes content. The model has a 7-speed gearbox with 2 shifter drums, suspension, V8 piston engine, adjustable rear wing, and opening dihedral doors with advanced mechanism – all guaranteeing an immersive building experience from start to finish that is authentic to the real McLaren P1.

The Lego Technic McLaren P1 set will be available from 1st August 2024 priced at €449.99 / £389.99 / $449.99.

[locally-normal]

I take it back, Dihedral groups of order 4n, that is, symmetries of a regular 2n-gon, suck. Fuck 2 it's a problem.

[iwannakissasopwithcamel]

Ritter Model S ‘Fink’ - "Astrid Ritter's Magnum Opus"

Role: Scout Served With: Macchi Republics First Flight: 1597 Strengths: Supreme Dogfighter Weaknesses: Unstable, Overspeed Inspiration: Sopwith Snipe (1918) Backer: Tom

Description:

The last Ritter rotary, the Model S consumed nearly half a decade of the designer’s life in perfecting it. A redesign of the Model F, improved in every way, the Model S carries the frightening W.O.3 230 horsepower engine. Both wings had to be given dihedral angles to compensate for the immense torque.

The Fink had aggressive turn characteristics, robust construction, and could outrun anything that could outturn it. Though they never completely replaced the Model F, it was soon known and feared by its enemies, and it was the last, best chance for the doomed Macchi Republics.

Though rare, many dogfight aces consider them to be the best rotary biplanes in the world. Few survived, most of them cut apart for the engines after Macchi surrendered, so each one is treasured