Private A and Private F


Private A (also designated XF 10S1000-A) - Private F (also XF 10Sl000-B)

Private A

Private A

Private F

Private F with booster - Credit: NASA/JPL


  • The Army Signal Corps established requirements for the rocket that met its meteorological payload needs.
    A study of the proposed sounding rocket, requested by the Ordnance Department was completed by Stewart and Frank Malina. Project ORDCIT resulted in development of the Private A and Corporal missiles.
  • The first missile to be tested used a solid propellant rocket engine that could be quickly provided, as proposed by Tsien and Frank Malina in 1943. It was called Private A, with the intention to name subsequent missiles in hierarchical order of army ranks. The JPL missile series ended in 1954 with the sergeant, a solid-propellant, surface-to-surface missile with an inertial guidance system.
  • The Private A (also designated the XF 10S1000-A) was designed to provide experimental data on the effect of sustained rocket thrust on a missile stabilized with fixed fins and on the use of the booster rockets for missile launching.
    It had a length of 92 in., a maximum diameter of 10.25 in. and four tail fins extending 12 in. from the body. The gross weight was 500-550 1b. The solid-propellant motor, manufactured by the Aerojct Engineering Corp. (now Acrojet General Corp.) delivered a thrust of 1,000 lb. for about 30 sec. The specific impulse of the asphalt-base castable propellant GALCIT 61C was 186 sec.
  • The Private's launcher was a 36-ft long rectangular steel boom of the truss type, with four guide rails inside the truss. It was mounted on a steel base and both the lateral and vertical angles could be varied. The missile was boosted by four modified Ordnance Department aircraft armament rockets in a cluster. The four rockets delivered a thrust of 22,000 lb for 0.18 scc. They completed their burning and disconnected from the missile before it left the launcher.
  • Firing tests were made in the Mojave Desemeach Springs, Camp Irwin, near Barstow, Califomia, between December 1-16, 1944.
    24 rounds were fired in all. The Private A booster rockets and missile rockets reportedly performed "satisfactorly." The average range for the fully charged rockets was 18,000 yards; the maximum range was 20,000 yards (11.3 miles). The missile reached an estimated peak height of 14,500 ft. and an estimated maximum speed of 1,300 ft/scc. Trajectory analyses were carried out by W.Z. Chien and C.C. Lin. The firing tests were completely successful, meeting all of the objectives specified for the program. The Private A became the precursor of composite propellant rocket engine missiles as the Sergeant, Polaris, Minuteman, and Poseidon and of anti-missile missiles.
  • The Private F:
    Tsien and F. Malina also proposed the addition of wings to a missile having the characteristics of the Private A, estimating that the range would be increased by about 50 percent with a reduced payload. We pointed out that the problems of stability and control of such an unguided missile were very complicated. The winged Private A was designated Private F (also the XF 10Sl000-B), and used the same Acrojet solid propellant engine. The missile was provided with fixed wings, having a span of 5 ft, stubby wings of 3 ft span were placed at the forward end for trimming the aerodynamic forces and, at the rear, horizontal stabilizers and a vertical fin. The same Private A booster rockets were used. A new launchers was constructed with two rails, in order to clear the wing and tail surfaces.
  • Test firings of the Private F rocket were carried out at Hueco Range, Fort Bliss, Texas between April 1 and April 13, 1945. The tests began on April Fool's Day and tumed out to be quite appropriate to the occasion.
    A total of 17 rounds were fired, including two dummies to test operations of the launcher and boosters. All of the Private F rounds, though successfully launched, went into a tail spin after a short flight. A striking corkscrew smoke trail was drawn in the sky by the rocket jet. Engineers concluded after a postmortem that better performance might have been obtained if the missile had been constructed with greater precision and if the lifting surfaces had been more readily adjustable. In earlier times, after the war, when the use of funds is more carefully scrutinized, programs such as the Private F would have begun only after more theoretical studies of such a complex devices had been made. and more care would have been taken in its construction.
  • 01 April 1945 Private F rockets tested.

Description of Firing Rounds:

Firing Description of Round Range or
1 Private F Dummy R: 375 yds Only booster fired to check launcher. Separation was satisfactory. Launcher satisfactory at 20 degree elevation.
2 Private F Dummy R: 400 yds Same as above. Launcher satisfactory at 40 degree elevation.
3 1/3 trust Pvt. F R: 1,100 yds Missile slow-rolled to left and dived into ground.
4 ditto R: 950 yds Pvt F. motor had very slow start and missile made unpowered ?ight. Unstable as above.
5 Full charged Pvt. F R: 1,300 yds Missile rolled and spiraled. Observers blamed excessive vertical fin.
6 ditto R: 2,000 yds 4" cut off vertical fin. Missile made slow rolling oscillations and then into barrel roll.
7 ditto R: 1,350 yds 6" out off vertical fin. Similar flight as above with more violent spiraling.
8 ditto R: 2,225 yds Vertical fin removed. Missile rolled rapidly after firing.
9 ditto R: 1,400 yds 5" cut from vertical fin and 4" off end of horizontal surface tips and bent up at 45 degrees.
10 ditto Misfire Round booster was blown out of breech and missile burnt out in launcher.
11 ditto R: 2,900 yds Using the tail of Round No.10. Round stable at first, then went into spin.
12 Full charged Pvt. F R: 1,450 yds 6" removed from vertical fin; 6" of horizontal surface bent at 45 degrees. Flight characteristics unchanged.
13 ditto R: 1,650 yds 5" removed from vertical fin, other dimensions same as Round 12. Flight characteristics unchanged.
14 Full charged Pvt. A R: 25,000 yds Pvt. A was modified to fit Pvt. F. Launched at 80 degrees. Missile was stable to 25,000 ft and then changed course 45 degrees and disappeared over mountains.
15 Full charged Pvt. F R: 5,075 yds Vertical front fin 5" long welded on nose. Rear fin left unchanged. Horizontal surfaces bent at 45 degrees as before. Missile stable in pitch and yaw, but unstable in roll.
16 ditto R: 2,150 yds Front fin increased to 11". Round very erratic in flight.
17 ditto R: 2,050 yds Compromise in specifications between rounds 15 and 16. Round very erratic.

Ref.: #57, #511(Quest 15:1 - 2008) - update: 07.08.15 Home