Jupiter-C

Jupiter-C

Jupiter-C on the launch pad at Cape Canaveral
Function Sounding rocket
Manufacturer Chrysler for the ABMA
Country of origin United States
Size
Height 69.9 feet (21.3 m)
Diameter 5.8 feet (1.8 m)
Mass 64,000 pounds (29,000 kg)
Stages 3
Capacity
Payload to
Sub-orbital		 11 kg
Launch history
Status Retired
Launch sites LC-5 and 6, Cape Canaveral Missile Annex, Florida
Total launches 3
Successes 1
Failures 1
Partial failures 1
First flight 20 September 1956
Last flight 8 August 1957
First stage - Redstone (stretched)
Engines 1 A-7
Thrust 42,439 kgf (416,180 N; 93,560 lbf)
Specific impulse 235 sec
Burn time 155 seconds
Fuel LOX/Hydyne
Second stage - Sergeant cluster
Engines 11 Solid
Thrust 7,480 kgf (73,400 N; 16,500 lbf)
Specific impulse 214 sec
Burn time 6 seconds
Fuel Solid
Third stage - Sergeant cluster
Engines 3 Solid
Thrust 2,040 kgf (20,000 N; 4,500 lbf)
Specific impulse 214 sec
Burn time 6 seconds
Fuel Solid

The Jupiter-C was an American sounding rocket used for three sub-orbital spaceflights in 1956 and 1957 to test re-entry nosecones that were later to be deployed on the more advanced PGM-19 Jupiter mobile missile. A member of the Redstone rocket family, Jupiter-C was designed by the U.S. Army Ballistic Missile Agency (ABMA), under the direction of Wernher von Braun.[1] All three flights were launched from Cape Canaveral, Florida.

Description

Each vehicle consisted of a modified Redstone ballistic missile with two solid-propellant upper stages. The tanks of the Redstone were lengthened by 8 ft (2.4 m) to provide additional propellant. The instrument compartment was also smaller and lighter than the Redstone's. The second and third stages were clustered in a "tub" atop the vehicle.

Redstone, Jupiter-C and Mercury-Redstone rockets compared
Second stage cluster

The second stage was an outer ring of eleven scaled-down Sergeant rocket engines; the third stage was a cluster of three scaled-down Sergeant rockets grouped within. These were held in position by bulkheads and rings and surrounded by a cylindrical outer shell. The webbed base plate of the shell rested on a ball bearing shaft mounted on the first-stage instrument section. Two electric motors spun in the tub at a rate varying from 450 to 750 rpm to compensate for thrust imbalance when the clustered motors fired. The rate of spin was varied by a programmer so that it did not couple with the changing resonance frequency of the first stage during flight.[2]

The upper-stage tub was visibly spun-up before launch. During first-stage flight, the vehicle was guided by a gyro-controlled autopilot controlling both air-vanes and jet vanes on the first stage by means of servos. Following a vertical launch from a simple steel table, the vehicle was programmed so that it was traveling at an angle of 40 degrees from the horizontal at burnout of the first stage, which occurred 157 seconds after launch.[3]

At first-stage burnout, explosive bolts fired and springs separated the instrument section from the first-stage tankage. The instrument section and the spinning tub were slowly tipped to a horizontal position by means of four air jets located at the base of the instrument section. When the apex of the vertical flight occurred after a coasting flight of about 247 seconds, a radio signal from the ground ignited the eleven-rocket cluster of the second stage, separating the tub from the instrument section. The third stage then fired to raise the apogee. Through this system, designed by Wernher von Braun in 1956 for his proposed Project Orbiter, the Jupiter-C obviated the need for a guidance system in the upper stages.[4]

Juno I

The Juno I was a satellite launch vehicle based on the Jupiter-C, but with the addition of a fourth stage, atop the "tub" of the third stage. The Juno name derived from von Braun wishing to make the satellite launch appear as peaceable as the Vanguard rocket, which was not a weapon, but was developed from a weather study rocket, the Viking. Since the Juno I was the same height as the Jupiter-C (21.2 meters), with the added fourth stage being hidden inside the shell, this vehicle which successfully launched the first orbital satellite of the United States is often incorrectly referred to as a Jupiter-C.

Encrypted serial number

As the Jupiter-C was part of the IRBM project, revealing the sequence of manufacture of the rockets (which are not necessarily launched in order, and may be uprated as solutions to technical problems are worked out in tests) would be revealing military secrets. So the designation painted on the sides of the rocket was not a serial number in clear text, but employed a simple transformation cypher that the staff would be sure not to forget. The key was taken from the name of the design and test base: Huntsville, Alabama, giving HUNTSVILE, with duplicated letters dropped: H was used for 1, U for 2, ..., E for 9 and X for 0. For example, the Jupiter-C modified to launch Explorer 1 had "UE" painted on the side, indicating it was S/N 29 (U→2, E→9).

General characteristics

Flight history

References

  1. ↑ 1.0 1.1 1.2 1.3 "Jupiter-C Explorer-I". NASA.
  2. ↑ "ABMA Juno I". Designation-systems.net. Retrieved 2013-03-25.
  3. ↑ Juno V Space Vehicle Development Program Report No. DSP-TM-10-58, NASA, October, 1958.
  4. ↑ Juno V Space Vehicle Development Program Status Report, DSP-TM-11-58, NASA, November, 1958.