Encyclopedia Astronautica
Blue Scout Junior

American suborbital launch vehicle. Smaller Air Force version of Scout used for suborbital military tests.

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:

Length 12.34 m (40 ft 5.8 in)
Finspan 1st stage: 2.62 m (8 ft 7 in)
2nd stage: 1.64 m (5 ft 4.6 in)
Diameter 0.79 m (31 in)
Weight 6300 kg (14000 lb)
Speed 6 km-s (20000 ft-s)
Altitude 225000 km (140000 miles)
Range global (low earth orbit reachable)
Propulsion 1st stage: Thiokol XM33 Castor solid-fuel rocket; 259 kN (58300 lb) for 37 s
2nd stage: Alleghany Ballistics Lab (Hercules) X-254 Antares solid-fuel rocket; 60.5 kN (13600 lb) for 39 s
3rd stage: Aerojet AJ10-41 (30KS8000) Alcor solid-fuel rocket; 36 kN (8000 lb) for 30 s
4th stage: NOTS 100A Cetus solid-fuel rocket; 4.0 kN (900 lb) for 20 s
Main Sources

[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

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

More... - Chronology...

Associated Countries
Associated Engines
  • Alcor Aerojet solid rocket engine. Originally developed for the Air Force as a third Stage for the Athena sounding rocket; in some applications known as Zebra. One of its main attractions was a very high mass fraction First flight 1960. More...
  • NOTS 100A NOTS solid rocket engine. Used on Blue Scout Junior launch vehicle. First flight 1960. More...
  • Program 661 EOS electric/cesium rocket engine. 8.9 mN. Flew 1962-1964. Isp=7400s. Cesium contact ion propulsion system used on three sub-orbital flight tests aboard Blue Scout Junior launch vehicles. More...
  • Snapshot EOS electric/cesium rocket engine. 8.5 mN. In Development, 1962-1964. Isp=5100s. Launched on Blue Scout Junior launch vehicle on Snapshot test; a contact ionization engine; thruster anode diameter was 5 cm. More...
  • TX-354-3 Thiokol solid rocket engine. 258.9 kN. Used in Scout A; Delta E; H-1-0; Castor 2. License built in Japan for H-1. Isp=262s. First flight 1960. More...
  • X-254 Thiokol solid rocket engine. 60.5 kN. Isp=256s. Used on Blue Scout 1, Blue Scout 2, Blue Scout Junior, Scout X-1. First flight 1960. More...

See also
  • Scout Solid-fuel, light payload, lower-cost launch vehicle developed by the Air Force and NASA in the late 1950's and used in a variety of configurations over thirty years. Launched from Cape Canaveral, Vandenberg, Wallops Island, and from Italy's equatorial San Marco platform off Kenya. Italy studied but did not develop subsequent upgraded versions. More...

Associated Manufacturers and Agencies
  • Vought American manufacturer of rockets and spacecraft. Vought, USA. More...

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