Asset Credit - USAF

One part of the Dynasoar manned spaceplane project was ASSET ( 'Aerothermodynamic Elastic Structural Systems Environmental Tests') . After cancellation of Dynasoar, flights continued of subscale unmanned spaceplanes in order to obtain test data applicable to later vehicles.

After the cancellation of Dynasoar, the Air Force pursued further development of manned spaceplanes under the START Project. This included the ASSET and PRIME/X-23 suborbital launch of subscale lifting body designs and B-52 drop tests of the X-24A and X-24B lifting body designs into the mid-1970's.

The first of the series was a carry-over from the X-20 and was called ASSET ( 'Aerothermodynamic Elastic Structural Systems Environmental Tests'). The project began in 1960, purportedly to use subscale models of the X-20 Dynasoar to test materials prior to full-scale manned flights. It had been originally planned to use the Scout launch vehicle, but the program switched to surplus Thor missiles returned from the United Kingdom for the 4,000 m/s flights and the Thor-Delta for the 6,000 m/s flights. An aero-thermodynamic structural test vehicle (ASV) was used for heat shield tests. The spacecraft flew on a suborbital trajectory to the recovery zone at Ascension Island.

However was ASSET really so closely related to the DynaSoar or was this just a cover for an entirely different, lower cost, manned spaceplane design? Giuseppe De Chiara points out:

.recently I was involved in a cycle of lectures, concerning manned spacecraft configuration, at the Aerospace Engineering Dept. of the University of Naples..analyzing Gemini family.I found that the drawing of the Winged Gemini in your page (credited Glen Swanson) is completely wrong. This drawing is clearly taken by the Flight Manual of the Gemini .and modified with the addition of a mid-line sleek triangular wing and "subsystem interconnection" (??!!) on the bottom.

As you said Winged Gemini was derived from the experience gained by the ASSET program. If you analyze the ASSET drawings you will find a bi-conic re-entry spacecraft with a low cranked arrow wing. Interestingly if scale-up the ASSET layout drawings you will match exactly Winged Gemini configuration (as portrayed in the other drawings).

These considerations put a new light on the ASSET (AEV and ASV) program - it seems clear that ASSET was never a subscale model of the X 20. In fact, there were a lot of configurational differences between the two vehicles, the former being a bi-conic shape with a very reduced wing without a vertical stabilizer, the latter was a "classic" hypersonic >75° degree delta wing with . two huge vertical stabilizers. It's also clear that the performances of the two vehicles (especially re-entry footprint crossrange) were completely different.

This leads (me) to think that ASSET could be a completely different spacecraft configuration later adopted by the hybrid Gemini capsule to increase its re-entry performance. The whole project was managed by Mc Donnell, which built both vehicles, under the cover of USAF funds (I always wondered why, if ASSET was a subscale model of X-20, why was it built by Mc Donnell, and not by Boeing, as prime contractor of the Dyna Soar project......?).

Following this train of thought it seems that the USAF (after cancellation of the X 20), continued to seek to have a small, and even cheaper, spaceplane obtained by the merging of the ASSET configuration and a Gemini spaceframe. Such a vehicle could be launched by a Titan II directly from a ICBM silo at Vandenberg AFB, in space interception mission with a highly secret profile.

Length: 1.79 m (5.87 ft). Maximum Diameter: 1.53 m (5.01 ft). Span: 1.53 m (5.01 ft). Mass: 540 kg (1,190 lb). RCS Propellants: H2O2. Electrical System: Batteries. Associated Launch Vehicle: Thor DSV-2G.

• 1960 January 1 - ASSET Project begun. -

  ASSET ( 'Aerothermodynamic Elastic Structural Systems Environmental Tests') involved suborbital flight of a small scale spaceplane model to test structural and materials concepts for the X-20 Dynasoar to test materials prior to full-scale manned flights.

• 1961 May 29 - Advanced Re-entry Technology program and SAINT II program. -

  The Space Systems Division completed two development plans for an Advanced Re-entry Technology program and a SAINT II program.

• 1963 December 11 - X-20 efforts important to other space programs be continued. -

  The Secretary of the Air Force directed that X-20 efforts important to other space programs be continued.

• 1963 December 13 - X-20 phase-out plan. -

  The X-20 System Program Office completed the first phase-out plan, and the X-20 Engineering Office compiled a list of useful efforts for continuation.

• 1963 December 19 - Allocation of X-20 hardware. -

  Representatives from various government agencies met at the system program office to determine the allocation of X-20 hardware.

• 1963 December 20 - Dyna-Soar termination plan. -

  Both the system program office and engineering office completed revisions to the termination plan and the list of efforts for possible continuation.

• 1963 December 27 - Dyna-Soar termination plan. -

  The program office again revised its termination plan.

• 1963 September 18 - ASSET 1 re-entry vehicle test flight - Launch Site: Cape Canaveral. Launch Vehicle: Thor DSV-2F. Apogee: 62 km (38 mi).

  Suborbital test of small scale spaceplane model to test materials for the X-20 Dynasoar. Aero-thermodynamic structural test vehicle (ASV) for heat shield tests. Booster flew to peak altitude of 62 km, then pitched down, driving the spacecraft to separation at 59 km and 4,906 m/s. The spacecraft was sited under its parachute in the recovery zone at Ascension Island, but the flotation bag broke and it sank into the Atlantic.

• 1964 December 9 - ASSET 5 re-entry vehicle test flight - Launch Site: Cape Canaveral. Launch Vehicle: Thor DSV-2F. Apogee: 53 km (32 mi).

  Suborbital test of small scale spaceplane model to test structural concepts for the X-20 Dynasoar. Aero-environmental test vehicle (AEV) to test aerodynamic properties of flexing outer skin with corrugated columbium panel. Reached 4,000 m/s at 53.2 km altitude before being released from launch vehicle. Telemetry received for 900 seconds until spaceplane had reached Mach 2 1200 km downrange. It then became unstable and crashed into the Atlantic. Recovery was not planned.

• 1964 January 23 - Asset project and other useful X-20 efforts to continue. -

  A final edition of the program office's termination plan was completed. USAF headquarters informed AFSC that the Secretary of the Air Force approved 36 tasks for continuation. for the continuaion of useful X-20 efforts.

• 1964 January 3 - Dyna-Soar termination plan. -

  Further revisions were made to the termination plan and the list of efforts for continuation.

• 1964 July 22 - ASSET 3 re-entry vehicle test flight - Launch Site: Cape Canaveral. Launch Vehicle: Thor DSV-2G. Apogee: 71 km (44 mi).

  Suborbital test of small scale spaceplane model to test materials for the X-20 Dynasoar. Aero-thermodynamic structural test vehicle (ASV) for heat shield tests. Launched after four hours of holds. Tested Dynasoar hardware - tungsten nose cap, molbdenum panels with vapor-deposited disilicide, and liquid-cooled double-walled cockpit bathtub panel. Reached 5,500 m/s and recovered near Ascension Island 12 hours after launch.

• 1964 March 24 - ASSET 2 re-entry vehicle test flight - Launch Site: Cape Canaveral. Launch Vehicle: Thor DSV-2G. FAILURE: Second stage fired, then shut down, repeating the sequence several times. Apogee: 55 km (34 mi).

  Suborbital test of small scale spaceplane model to test materials for the X-20 Dynasoar. Aero-thermodynamic structural test vehicle (ASV) for heat shield tests. Good first stage burn, but the second stage fired, then shut down, repeating the sequence several times. The spacecraft separated, and began to maneuver in a 60 degree bank to recover course, when the self-destruct package blew it apart. The debris impacted the Atlantic 800 km downrange near San Salvador Island.

• 1964 October 28 - ASSET 4 re-entry vehicle test flight - Launch Site: Cape Canaveral. Launch Vehicle: Thor DSV-2F. Apogee: 50 km (31 mi).

  Suborbital test of small scale spaceplane model to test structural concepts for the X-20 Dynasoar. Aero-environmental test vehicle (AEV) to test aerodynamic properties of flexing outer skin with corrugated columbium panel. Reached 4,000 m/s at 50.6 km altitude before being released from launch vehicle. Telemetry received for 900 seconds until spaceplane had reached Mach 2 1200 km downrange. It then became unstable and crashed into the Atlantic. Recovery was not planned.

• 1965 February 23 - ASSET 6 re-entry vehicle test flight - Launch Site: Cape Canaveral. Launch Vehicle: Thor DSV-2G. Apogee: 70 km (43 mi).

  Suborbital test of small scale spaceplane model to test materials for the X-20 Dynasoar. Reached 6,000 m/s and 4,350 km range. Tested twelve different kinds of refractory metals and covered with 2000 dots of heat-sensitive paint to characterize thermal profile on reentry. Telemetry indicated that the spacecraft survived reentry, but it evidently sank upon impacting the ocean and could not be recovered as planned.

• Houchin II, Roy and Smith, Terry, Quest, "X-20 (7 articles)", 1994, Volume 3, Issue 4, page 4.

• Peebles, Curtis, Spaceflight, "The Origins of the US Space Shuttle - 1", 1979, Volume 21, page 435.

• Krebs, Gunter, Gunter's Space Page, University of Frankfurt, 1996. Accessed at: http://www.skyrocket.de/space.

• Gatland, Kenneth, Manned Spacecraft, Macmillan, New York, 1968. ISBN: 0025428209. First of a marvelous series of pocket-size hardbacks covering spacecraft and rocketry. More at amazon.com...

• Miller, Jay,, The X-Planes, Aerofax, Arlington, Texas, 1988. ISBN: 1857801091. Tremendous account of the entire X- experimental series of US aircraft, including the rocket planes X-1, X-15, and X-20. Another outstanding Jay Miller book. More at amazon.com...

• Desind collection, NASM archives (via Jonathon McDowell).

• Arms, Thor history, 1972 (via Jonathon McDowell).

• Missiles and Rockets, MR650301-12 (via Jonathon McDowell).

• In JSR private files; original reference mislaid. (via Jonathon McDowell).

• Bramscher, Robert G, Spaceflight, "A Survey of Launch Vehicle Failures", 1980, Volume 22, page 351.