#North American RockwellNAR-161-B

[lonestarflight]

Space Shuttle Development, Phase B: North American Rockwell and General Dynamics B9U/NAR-161-B

North American and General Dynamics B9U / NAR-161-B proposed their final Phase B shuttle proposal on June 25, 1971.

"The fully reusable 'B9U / NAR-161-B' configuration would now weigh 2,290t at liftoff vs. the Phase-A limit of 1,587t and the total estimated cost of the development project had doubled, to almost $10 billion. The thrust of the space shuttle main engines had to be increased from 1,850KN to 2,450KN. Part of the problem was the shuttle now would have to be a much more versatile and capable vehicle than originally anticipated, since the space station and the manned lunar/planetary program evaporated in 1970. Critics in Congress contended that it was 'a project searching for a mission.' As a result, the new space transportation system was instead increasingly being promoted as a low-cost 'space truck' for unmanned NASA & USAF satellites."

"The North American Rockwell 'NAR-161-B' orbiter was designed for carrying a crew of two plus up to ten passengers in the forward crew module. Note the four deployable landing jet engines on top of the vehicle; NASA was planning to use modified F-15 or B-1B aircraft jet engines on some missions and for ferry flights from test sites or alternative landing fields. But the jets would be omitted for heavy-lift missions since the additional weight greatly reduced the shuttle's payload capability. The thermal protection system was based on silica tiles. The blended wing/body design was chosen for uniform load distribution. It would have produced a 2300-kilometer crossrange capability to satisfy USAF reentry requirements; North American also decided to replace the wingtip fins with a single vertical tail. The 2,450KN main engine thrust upgrade was motivated in part by the need to have a single engine-out abort capability. Analysis showed that the orbiter still would be able to return to the launch site after a single orbit in case one of its two main engines failed during ascent, but only if the engines were powerful enough. Unlike McDonnell-Douglas (who proposed to use RL-10s), North American favored a brand new oxygen/hydrogen 45KN-thrust orbital maneuvering system (OMS) engines. Three OMS engines would have been carried for orbit insertion, orbital changes and the de-orbit burn."

"General Dynamics' final 'B9U' booster design differed considerably from the earlier straight-wing 'B8D' concept. The landing jets were moved from the nose back to the delta wing in order to reduce the launch drag & heating effects and to minimize the jet engine exhaust effects on stability, control and drag. General Dynamics felt the delta wing would provide better stability & control over the entire flight regime than the B8's straight wing. It would also create more room for the main landing gear and jet engine installation. The gross liftoff mass was 1,886.2t including a jet fuel load of 62.2t for the 850km flight back to the launch site. The high staging velocity (3300m/s) and altitude (73.8km) created some problems since the booster would have to be very large, require a relatively advanced thermal protection system and carry lots of jet fuel for the return flight. The contractors also examined downrange landing sites or in-flight propellant transfer in order to reduce the amount of booster jet fuel. NASA also seriously considered a proposal to use gaseous hydrogen rather than jet fuel since it would have saved thousands of kilograms, but decided against the idea in the end since it would have increased the technical risk."

North American Rockwell Phase-B shuttle orbiter docks with modular space station.

"Payload capability (without landing jets): 29,484kg into a 185km 28.5 deg. Orbit; 18,144kg into a 185km 90 deg. polar orbit; 11,340kg into a 500km 55 deg. orbit with landing jets installed on orbiter and 20,411kg without landing engines.

Cost per mission: $100-200/lb. [1970 rates] or $950-$1900/kg in 1999. 75 missions/year max. Space station rescue mission capability within 48 hours of emergency call.

Liftoff Thrust: 2,606,810 kgf. Total Mass: 2,188,488 kg. Core Diameter: 10.4 m. Total Length: 98.0 m.

Stage Number: 1. 1 x Shuttle R134C-1 Gross Mass: 1,886,200 kg. Empty Mass: 290,000 kg. Thrust: 29,370-32,233.575 KN. Isp: 442 sec. Burn time: 209 sec. Isp(sl): 392 sec. Diameter: 10.4 m. Span: 43.9 m. Length: 82 m. Propellants: Lox/LH2 No Engines: 12. SSME Study

Stage Number: 2. 1 x Shuttle R134C-2 Gross Mass: 383,260 kg. Empty Mass: 121,560 kg. Thrust (vac): 5,624.8 KN. Isp: 459 sec. Burn time: 264 sec. Isp(sl): 359 sec. Diameter: 4.6 m. Span: 32.6 m. Length: 62.8 m. Propellants: Lox/LH2 No Engines: 2. SSME Study

- information from "INTRODUCTION TO FUTURE LAUNCH VEHICLE PLANS [1963-2001]" by Marcus Lindroos: link

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Boeing image: 71SV13043