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Blue Scout Junior

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AKA: XRM-91. Status: Out of production. Payload: 10 kg (22 lb). Thrust: 222.40 kN (49,998 lbf). Gross mass: 5,797 kg (12,780 lb). Height: 14.00 m (45.00 ft). Diameter: 0.79 m (2.59 ft). Apogee: 27 km (17 mi).

The Blue Scout Junior was a four-stage rocket based on the NASA/LTV Scout family. Blue Scout Junior and its derivatives were used throughout the 1960s and 1970s by the USAF under the designation of SLV-1.

Payload: 10 kg (22 lb) to a 26.775 km altitude, 11,290 km range.

Stage Data - Blue Scout Junior

• Stage 1. 1 x Castor 2. Gross Mass: 4,424 kg (9,753 lb). Empty Mass: 695 kg (1,532 lb). Thrust (vac): 258.915 kN (58,206 lbf). Isp: 262 sec. Burn time: 37 sec. Isp(sl): 232 sec. Diameter: 0.79 m (2.59 ft). Span: 0.79 m (2.59 ft). Length: 6.04 m (19.81 ft). Propellants: Solid. No Engines: 1. Engine: TX-354-3. Status: In Production.

• Stage 2. 1 x Antares 1A. Gross Mass: 1,225 kg (2,700 lb). Empty Mass: 294 kg (648 lb). Thrust (vac): 60.497 kN (13,600 lbf). Isp: 256 sec. Burn time: 39 sec. Isp(sl): 233 sec. Diameter: 0.78 m (2.55 ft). Span: 0.78 m (2.55 ft). Length: 3.38 m (11.08 ft). Propellants: Solid. No Engines: 1. Engine: X-254. Status: Out of Production.

• Stage 3. 1 x Alcor. Gross Mass: 520 kg (1,140 lb). Empty Mass: 50 kg (110 lb). Thrust (vac): 35.588 kN (8,001 lbf). Isp: 230 sec. Burn time: 30 sec. Diameter: 0.46 m (1.50 ft). Span: 0.46 m (1.50 ft). Length: 1.37 m (4.49 ft). Propellants: Solid. No Engines: 1. Engine: Alcor. Status: Out of Production. Comments: Masses, specific impulse estimated.

• Stage 4. 1 x Cetus. Gross Mass: 50 kg (110 lb). Empty Mass: 10 kg (22 lb). Thrust (vac): 4.001 kN (899 lbf). Isp: 230 sec. Burn time: 20 sec. Diameter: 0.43 m (1.41 ft). Span: 0.43 m (1.41 ft). Length: 0.51 m (1.67 ft). Propellants: Solid. No Engines: 1. Engine: NOTS 100A. Status: Out of Production. Comments: Masses, specific impulse estimated.

Historical Essay � Andreas Parsch

Ford RM-91 Blue Scout Junior

The XRM-91 Blue Scout Junior (sometimes called Journeyman B) was a rocket of the U.S. Air Force's System 609A Blue Scout family (for general information on Blue Scout, see article on RM-89 Blue Scout I). The XRM-91 did not resemble the other Scout variants externally, because the usual first Scout stage (an Aerojet General Algol) was not used. Instead, the four-stage Blue Scout Junior used Scout's 2nd and 3rd stages (Castor and Antares) as the first two stages, and added an Aerojet General Alcor and a spherical NOTS Cetus in a common nose fairing. The XRM-91 also lacked the gyro-stabilization and guidance system of the RM-89 Blue Scout I and RM-90 Blue Scout II, making it a completely unguided rocket. It relied on second-stage fins and two spin motors to achieve a stable flight trajectory.

The first launch of an XRM-91 occurred on 21 September 1960, making it actually the first Blue Scout configuration to fly. The flight was planned to make radiation and magnetic field measurements at distances of up to 26700 km (16600 miles) from earth, and while the rocket did indeed achieve this altitude, the telemetry system failed so that no data was received. The second launch in November ended with a failure during second stage burn. The third flight was to measure particle densities in the Van Allen belts and reached a distance of 225000 km (140000 miles), but again a telemetry failure prevented the reception of scientific data. The fourth and final XRM-91 mission in December 1961 also carried particle detectors, and was the only completely successful flight of the initial Blue Scout Junior program. The Blue Scout Junior would have been easily powerful enough to put a small satellite in low-earth orbit but was never used to do so.

The Blue Scout Junior was regarded by the USAF as the most useful of the various Blue Scout configurations. It was used (in slightly modified form) between 1962 and 1965 by the Air Force as the SLV-1B-C launch vehicle for suborbital scientific payloads. The SLV-1C was also chosen as the rocket for the MER-6A interim ERCS (Emergency Rocket Communications System) vehicle. The NASA used a three-stage Blue Scout Junior configuration (omitting the Cetus 4th stage) as the RAM B.

Note: Data given by several sources show slight variations. Figures given below may therefore be inaccurate!

Data for XRM-91:

[1] Peter Alway: "Rockets of the World, 2000 Supplement", Saturn Press, 2000
[2] Norman J. Bowman: "The Handbook of Rockets and Guided Missiles", Perastadion Press, 1963
[3] Mark Wade: Encyclopedia Astronautica

Family: suborbital launch vehicle. Country: USA. Engines: Program 661, Snapshot engine. Stages: Antares 1A, Alcor, Castor 2, NOTS 100A. Agency: Vought.