Space Cover #558: What Do the X-23, X-24, X-RV, and X-38 Have in Common?Just under 50 years ago, on April 22, 1970, Air Force test pilot Jerry Gentry flew the rocket powered X-24A lifting body on its third powered flight, expanding its' speed out to Mach 0.925, as commemorated on the event cover above. This cover was postmarked at Edwards on the flight date and had the X-24A Boy Scout Cachet (blue rubber-stamped words) added. The servicer penciled in the flight number and pilot's name. Gentry later autographed the cover.
In the 1960's NASA and the Air Force were studying ways to land manned spacecraft on a runway, research that ultimately led to the Space Shuttle. Keeping the wings from melting away at orbital re-entry speeds was a tough problem back then. So, one of the approaches was to do away with wings and make the spacecraft's body do all the lifting required for the landing, hence the term "lifting body." From the mid-60's into the 70's, three rocket powered lifting body concepts went through piloted landing tests at Edwards AFB and are shown below.
NASA developed two concepts – the half-cone shaped M2F2 (center) and the airfoil shaped HL-10 (right). Meanwhile Martin-Marietta and the Air Force were developing the "potato shaped" SV-5 configuration, resulting in the X-24A (left). The X-24A performed 28 manned landing tests between 1969 and 1971, and event covers like that above are fairly easy to find, usually with the Boy Scout rubber stamped word cachet.
From 1966 to 1967, three subscale unmanned versions of the SV-5 configuration, called the X-23 or PRIME (Precision Recovery Including Maneuvering Entry) were fired down the Pacific Missile Range on Atlas boosters to re-enter at near orbital speeds. The results of these three tests were so good that the fourth PRIME test article was not needed for flight test. An event cover for PRIME 1 is shown above, postmarked on its' flight date December 21, 1966 at Vandenberg AFB, with a Sarzin Cachet. PRIME covers are not plentiful and moderately difficult to find.
All of the PRIME and X-24A testing led science fiction author Martin Caidin to feature an SV-5 based rescue craft called the X-RV in the award-winning film version of his novel, "Marooned" in 1970.
Many of you have covers for the X-24B lifting body landing tests that took place from 1973 to 1975 at Edwards AFB. For X-24B, the X-24A was highly modified into a "flatiron" shape that took it away from the SV-5 potato-shaped configuration. Since it deviated from SV-5, we'll discuss the X-24B more in a subsequent SCOTW.
Well, by the mid-1970's, the problem of wings melting away appeared to have been solved, and a winged design was chosen for the Space Shuttle. So, the lifting bodies got parked.
In the late 1990's the SV-5 configuration was resurrected in a concept for a quick, simple "lifeboat" vehicle to be docked at the International Space Station (ISS) and used if the crew had an emergency requiring them to leave the ISS. The landing concept here was that the lifting body re-entered the atmosphere and automatically maneuvered down to a certain altitude where a parafoil opened to bring the rescue craft (and its potentially debilitated or rusty crew) to a soft landing. A test version, known as the X-38, underwent unmanned landing tests at Edwards. A Boyd cachet cover for the first of these landing tests, postmarked March 12, 1998 at Edwards is shown above. Note the red/white/blue parafoil with the (yup, potato shaped) white/black X-38 below in the cachet photo.
However, the operations concept for ISS was changed to always have enough Soyuz spacecraft docked to ISS to preclude the need for a dedicated lifeboat vehicle, so the SV-5 configuration still didn't get to fly people in space.
Maybe SV-5 will reappear again?
posted 04-12-2020 01:54 PM
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