HISTORIAN'S CORNER - October, 2005

BY: Matt Grogan

In my last article, I wrote about the X-24B aircraft program that was performed in Denver in the late 60's, and I asked readers for the names of the people that worked on the program. Clarence Cole called and told me that Dick Boss was the Program Manager, Wait Habicht, Rich Boydstun, and Art Bees worked structures, he (Clarence) was the Master Lines guy, and Dabby Dabkowski was the Manufacturing Manager. Dabby also called and has given me a nice model of the X-24B, which I will put in our Mars Room in the Engineering Building. Clarence told me an interesting story about being called up to Dick Boss' office one day near the end of the program, and Dick asked him to bring some modeling clay. When Clarence arrived at Dick's office, Dick told him to use the clay to fair-in an indentation on the side of the fuselage on a rough full scale model of the X-2413, according to the instructions of the NASA representative who was in the office. After Clarence finished and the NASA rep was satisfied, Dick asked the NASA rep to sign the model and that became the approved final design for the vehicle!

In this article, I thought I would follow up on the X-24B story with some information on the PRIME Program, the predecessor program of the X-24A and X-24B. The PR [ME program contract was awarded by the Air Force to Martin Baltimore in December 1964. Four unmanned PRIME vehicles were built in the Baltimore plant and three were launched atop Atlas missiles from Vandenberg AFB between December 1966 and April 1967 (Ref. 1, pg. 388). All program objectives were accomplished with three flights. The PRIME vehicle was 6.7 ft. in length with a 3.9 ft. wing span (Ref. 2) and was covered with an ablative material which Martin had developed (Ref. 1). PRIME was followed by the manned X-24A program also built by Martin Baltimore which was flown by the Air Force 28 times from April 1969 to June 1971. It was scaled up from the same lifting body shape as PRIME to explore the lower regions of the reentry corridor. The X-24A was 24.5 ft. in length, approximately 13.5 ft. at the widest part of its wedge shape, and powered by a XLR-1 1 rocket engine. Martin Co. and the USAF hoped ft would lead to a larger Titan III-launched manned orbital terry vehicle (cinematically embodied in the 'XRV spacecraft in the 1969 film version of Martin Caidin's novel 'Marooned') (Ref. 3).

I learned that Jim Sterhardt had worked on the PRIME program so I contacted him. Jim, who retired as a VP from Denver in 1991, graciously provided the following account of the program via e-mail: "in about 1959, a lifting body program was started in Baltimore, led by Joe Putegnat. John Rickey and Hans Multhop were the aero and configuration guys that developed the basic configuration. Hans was chief engineer at a German aircraft company during WII. Laird Kinnaird developed the heat shield ablative material assisted by Dan Sallis and Ed Sparhawk. The heat shield was tested in a Plasma Arc facility that was built in Baltimore and then transferred to Denver in 1968."

"There were several competing designs of entry vehicles that were considered by the AF. GE had one that provided cross range by moving the center of gravity during entry. NASA had one somewhat like the SV-5 but had a flat top and a rounded bottom (opposite of SV-5), and McDonnell Douglas had a vehicle that skipped out of the atmosphere. But the Air Force, with Aerospace technical assistance, picked the SV-5, and we were awarded a $43 million contract in December 1964. Barry Moss headed up the Aerospace effort, he later became the chief Aerospace guy on the Titan Programs.

"The Program was called PRIME (Precision Recovery Including Maneuvering Entry). The vehicle was to launched from an Atlas at hypersonic and high supersonic speeds to demonstrate cross range capability, stability, performance and the heat shield performance. There were to be four flights with cross-range up to 600 NM. The SV-5 lift-to-drag ratio was 1.4 at a 14-degree angle of attack. Airborne recovery of the vehicle after flight was to be demonstrated. Buzz Hello was Program Manager and Ordway Gates was in charge of engineering. In 1965, Ordway left for GE and I took over engineering."

"PRIME 2 Ws and its nose cone were made of carbon-carbon composite. The ailerons had gold plated bearings to provide lubrication during excessive entry heating. The guidance system was provided by Honeywell in Florida. It was a strap-down pulse rebalance system that brought the vehicle to within 300 ft. of its target after 5000 miles. We got four guidance systems including development, test and qualification for $2 million dollars. Try doing that today!!"

"The first launch of PRIME was December 21, 1966. ft performed perfectly throughout the flight to its target near Kwajalein, but was not recovered because of a breakaway bolt did not breakaway, and the parachute system did not deploy. The second flight was in Feb. 1967 and was perfect and demonstrated about 570 nm of cross range. The Air Force pick-up plane, however, did not find it and so ft was not recovered. The guys at VAFB told me that they had named our program "Voyage to the Bottom of the Sea." I laughed but A really wasn't that funny- Need a sense of humor though."

"The third flight was in April 1967, and it was recovered by the AF after 620 nm of cross range, and ft performed perfectly in every way. The recovery by the Air Force cargo plane used a net deployed out the back of the airplane to catch the PRIME vehicle. The vehicle was slowed down after reentry by a drogue chute and parachute (ballute) provided by Goodyear in Akron. The recovery aircraft grabbed hold of the parachute and pulled ft into the aircraft. Since all objectives had been met in the three flights, the AF canceled the fourth flight, and the program came to an end. The recovered SV-5 is in the Dayton AF museum, I believe."

"Folks that worked on this program included Ed Sparhawk, who helped develop the PRIME heat shield ablative material. The ablative material was made of silicone based resin with glass microballstor filler along with some cork. Ed later modified the PRIME ablator shield for use on the Viking Lander aeroshell. Other derivatives of that ablator material were used on the Space Shuttle External Tanks, and on the after burners of a number of GE jet engines for commercial airliners. John Mellin developed the heat shield instrumentation. Bill Maccalous was in charge of Manufacturing Engineering. Ben Groninger was in charge of stress, Bill AN had weights, Gus Mullen and Tom May, materials, and Frank Click and Fred Michelle had aerodynamics. Eric Strauss and Carroll Gray who worked on the PRIME heat shield eventually went to Michoud to develop the ablative material for the external tank, which was an even lighter version of the SV-5 ablator. Ed Widmayer, now retired from Boeing, was in charge of test. Also on the Prime program were Bud Click, Charlie Pirelto, John Baxter, Wally Olmer, Joe Burghardt, Jim Hudson, Ernie Koltay, Jim Magestro, Herb Miller, Joe Zuraw, George Wendt, Don Reisert, Bev Jones, Carroll Gray, Gus Mullen, Ted Gittner, Tom Hay, Ernie Schumacher, Gerry Sardella, Watt Krzymowski, Bill King, Arnold Black, Paul Brennan, George Stewart, and John Dengler."

Thanks, Jim, for providing your insight into this program. Anyone with further recollections of PRIME or the X-24A program, please give me a call.

Reference 1: "Raise Heaven and Earth", Harwood, 1993
Reference 2: "Encyclopedia Astronautica, www.astronautix.com/craft/prime.htm
Reference 3: "Encyclopedia Astronautics, www.astronautix.com/craft/24a.htm