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Private was an experimental rocket developed by the California Institute of Technology on behalf of the United States Army. Tested in two different configurations, it provided the proof of concept that a fin-stabilised ballistic missile was technologically feasible, and led to the development of the Corporal ballistic missile. The Private was the second in a series of JPL rockets for the US Army whose names correspond to the progression in Army enlisted ranks, starting with Recruit, and led to Corporal and finally Sergeant.

Private F with booster.jpg
Private F
FunctionExperimental rocket
ManufacturerGuggenheim Aeronautical Laboratory
Country of originUnited States
Height2.34 metres (7 ft 8 in)
Diameter240 millimetres (9.6 in)
Width0.86 metres (2 ft 10 in) finspan
Mass240 kilograms (529 lb)
Launch history
Launch sitesCamp Irwin, Fort Bliss
Total launches41
First flightDecember 1, 1944
Last flightApril 13, 1945
Booster stage – T22
Thrust24.5 kN (5,500 lbf) each
Burn time0.2 seconds
Sustainer stage
Thrust4.4 kN (990 lbf)
Burn time30 sec


The Private program was begun in 1944 as an outgrowth of work by the California Institute of Technology's Guggenheim Aeronautical Laboratory that had produced the first practical jet-assisted take-off (JATO) rockets.[1] A proposal to adapt the JATO rockets for research into the development of ballistic missiles was accepted, and the first flight of the Private A rocket, developed under the direction of Tsien Hsue-shen,[2] took place in December 1944, conducted at Camp Irwin in California.[3]

Private A was an unguided, fin-stabilised ballistic rocket; it consisted of a JATO unit equipped with cruciform tail fins, and a set of four T22 booster rockets that were jettisoned after launch.[1] This made Private A the first multistage rocket to be flown in the United States.[4]

24 launches of Private A were conducted at Camp Irwin between December 1 and December 16, 1944.[3] The tests were considered successful, Private A proving capable of flights of 18,000 metres (20,000 yd), and in January 1945 full funding for the ballistic missile program was provided, with GALCIT changing its name to Jet Propulsion Laboratory.[1] A new version of Private, Private F, was developed; the rocket was similar to Private A, except an aircraft-like tail assembly was fitted instead of Private A's cruciform fins.[1] A test series of Private F launches was conducted at Fort Bliss in Texas between April 1 and April 13 in 1945;[3] 17 launches were conducted, however none of them were successful, the rocket proving to have serious stability problems;[5] it was determined that while fin stabilisation was workable, a winged missile would require an autopilot.[6]

Following the conclusion of the Private program, the lessons learned were applied to the development of the SSM-A-17 Corporal ballistic missile.[1]

References and notesEdit

  1. ^ a b c d e Parsch, Andreas (2004). "JPL (GALCIT) Private". Directory of U.S. Military Rockets and Missiles Appendix 4: Undesignated Vehicles. Retrieved 2014-05-15.
  2. ^ Perrett, Bradley (2008-01-06). "Qian Xuesen Laid Foundation For Space Rise in China". Aviation Week & Space Technology. Archived from the original on 2011-05-21.
  3. ^ a b c Ley, Willy (1951 - revised edition 1958) [1944]. Rockets, Missiles and Space Travel. New York: The Viking Press. p. 250. Check date values in: |year= (help)
  4. ^ "Corporal History". U.S. Army. Archived from the original on 2007-03-10.
  5. ^ Bluth, John. "Malina, Frank Joseph". American National Biography Online. American National Biography. Retrieved 2008-06-13.
  6. ^ Johnson, Stephen B. (2006). The Secret of Apollo: Systems Management in American and European Space Programs. Baltimore, MD: Johns Hopkins University Press. p. 83. ISBN 978-0801885426.

External linksEdit

  • Private at Encyclopedia Astronautica