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X-15B
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Part of X-15A
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Navaho/X-15
Navaho/X-15
Credit: Mark Wade
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American manned spacecraft. Study 1958. North American's proposal for
the Air Force initial manned space project was to extend the X-15
program. The X-15B was a 'stripped' X-15A with an empty mass of 4500
kg.
Status: Study 1958. Thrust: 262.45 kN (59,000 lbf). Gross mass:
13,500 kg (29,700 lb). Unfuelled mass: 4,500 kg (9,900 lb). Specific
impulse: 276 s. Height: 15.00 m (49.00 ft). Span: 6.80 m (22.30 ft).
It would use a three-stage Navaho-derived launch vehicle to achieve a
single orbit with an apogee of 120 km and a perigee of 75 km.
In the aftermath of Sputnik 2, the Air Force quietly asked its
leading contractors for "unsolicited" proposals for manned spacecraft
that could be quickly executed and beat the Russians in putting a man
in orbit. Harrison Storms of North American conceived of a bold move
to get an American into space as quickly as possible, in order to
beat the Russians in the next obvious step of the space race. North
American had a warehouse full of partially-completed G-38 boosters
for the just-canceled Navaho missile program. Storms threw together a
proposal to cluster them four of them in order to launch an orbital
version of the company's X-15 manned rocketplane. He took the
proposal to the Air Research and Development Command (ARDC) at Wright
Field in November 1957.
Storms' X-15B was a 'stripped' X-15A with an empty mass of 4500 kg.
The launch vehicle consisted of 4 x G-26 Navaho booster stages plus
the X-15B's own XLR-99 engine. These would allow the X-15B to achieve
a single orbit with an apogee of 120 km and a perigee of 75 km. Due
to the low perigee and aerodynamics of the X-15, no retrorocket was
required, although the X-15's restartable engine could be used if
necessary. Using its cross range capability of about 800 to 1,000 km,
the X-15 would ditch in the Gulf of Mexico. The heat shield would
consist of beryllium oxide and Rene 41 alloy. The pilot would eject
and land by parachute, with the aircraft being lost. The spacecraft
had a ballistic coefficient (W/CdA) of 250 kg per square meter. It
was expected that a first manned orbital flight could be achieved 30
months after a go-ahead at a cost of $ 120 million.
The general in charge of ARDC found it interesting but said there was
no official requirement to orbit a man in space. But the political
pressure to do something in response to Sputnik mounted, and a secret
conference was held at on 29-31 January 1958 at Wright field. Eleven
aircraft and missile firms outlined for the Air Force and NACA
observers the various classified proposals for a manned satellite
vehicle that they had submitted during November and December 1957.
The ARDC boiled down the 11 proposals to the three that had the best
chance of quick realization - the X-15B, acceleration of the nascent
program for the X-20 Dynasoar winged space glider, or one of the
simple ballistic capsule designs, boosted by an existing launch
vehicle. On 27 February they took these straight to Curtis LeMay,
head of the Strategic Air Command, who's main comment was, "Where's
the bomb bay?" Nevertheless, he instructed ARDC to select one of the
concepts and submit a detailed plan for an Air Force man-in-space
program as soon as possible.
On 10-12 March ARDC held a conference at its Ballistic Missile
Division (BMD) in Los Angeles of more than 80 rocket, aircraft, and
human-factors specialists. The objective was to reach agreement on a
plan to get a man-in-space - soonest - in accordance with LeMay's
orders. The BMD itself had its sights set on Project Lunex, a long
term plan to establish an Air Force base on the moon before 1970.
Unfortunately for Storms, the consensus at the conference was that
the "quick and dirty" approach would consist of a simple ballistic
capsule using parachutes for a water landing, weighing around 1300
kg. This would be 1.8 m in diameter and 2.4 m long. The capsule would
be completely automated - the human-factors people felt there was no
certainty that a pilot could function under the stresses of space
flight. This last point seemed to rule out the piloted X-15B
approach.
ARDC continued on the Manned-in-Space-Soonest project into August
1958, and in June Storms had even been told he would receive the
contract for the manned spacecraft. But meanwhile, President
Eisenhower and the Congress had created a new civilian Agency to take
on the Soviet spaceflight challenge - NASA. And Max Faget, the lead
spacecraft designer at NASA, was one of the originators of the
ballistic capsule concept. The USAF budget for the initial manned
spacecraft was transferred to NASA, and with it evaporated Storms'
expected contract, and the X-15B. The contract for what NASA renamed
project Mercury would go to McDonnell.
This was not quite the end of the orbital X-15. It was known that
North American later proposed use of four Titan I booster stages in
place of the Navaho boosters.
Note
The notes of NACA engineer Clarence A. Syvertson from this meeting
indicate that four Navaho G-26 boosters would be used. The biography
of Harrison Storms indicates that G-38 boosters were proposed. A
quick calculation showed that four G-26 boosters could not get the
X-15 into orbit; G-38 boosters just about could. So in this case
physics and the memory of Storms trump the contemporaneous notes. It
was likely in any case that the boosters proposed were derived from,
but not identical to the G-26 or G-38 boosters.
A drawing also emerged of an X-15 atop a single G-26 booster. It was
likely that a program of slow build-up to orbital speeds, using
Navaho surplus assets, was proposed.
Crew Size: 1. Spacecraft delta v: 2,450 m/s (8,030 ft/sec).
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Family: Manned spacecraft. Country: USA. Engines: XLR99. Propellants:
Lox/Ammonia. Agency: USAF, North American. Bibliography: 26, 44, 4472
, 483, 59.
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