Air Force version of Scout used for suborbital and orbital military tests. 4 stage vehicle consisting of 1 x Algol 1 + 1 x Castor + 1 x Antares + 1 x Altair

Historical Essay © Andreas Parsch

Ford RM-90 Blue Scout II

The XRM-90 Blue Scout II 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-90 was a four-stage rocket, which used the same stages as the basic NASA Scout. It was nevertheless not identical to the latter, because the 4th stage was hidden in a payload fairing with the same diameter as the 3rd stage, and the first stage nozzle used a flared tail skirt between the fins. Externally, the XRM-90 was indistinguishable from the XRM-89 Blue Scout I.

The first XRM-90 launch occurred on 3 March 1961, followed by a second one on 12 April 1961. Both sub-orbital flights were successful, and measured radiation levels in the Van Allen belts. The second Blue Scout II also carried a micrometeorite sampling experiment, but the recovery of the reentry capsule failed. The third XRM-90 was used by NASA in November 1961 in an attempt to launch a communications payload for Project Mercury into orbit, but this rocket failed. The USAF subsequently abandoned the XRM-89 Blue Scout I and XRM-90 Blue Scout II vehicles, and shifted to the RM-91/SLV-1B Blue Scout Junior instead.

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

Data for XRM-90:

[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

Manufacturer: Vought. Launches: 3. Failures: 1. Success Rate: 66.67%. First Launch Date: 1961-03-03. Last Launch Date: 1961-11-01. Launch data is: complete. LEO Payload: 30 kg (66 lb). to: 300 km Orbit. at: 28.00 degrees. Apogee: 2,500 km (1,500 mi). Liftoff Thrust: 511.500 kN (114,990 lbf). Total Mass: 16,874 kg (37,200 lb). Core Diameter: 1.02 m (3.34 ft). Total Length: 24.00 m (78.00 ft).

• Stage Number: 1. 1 x Stage: Algol 1. Gross Mass: 10,705 kg (23,600 lb). Empty Mass: 1,900 kg (4,100 lb). Thrust (vac): 470.934 kN (105,870 lbf). Isp: 236 sec. Burn time: 40 sec. Isp(sl): 214 sec. Diameter: 1.01 m (3.31 ft). Span: 1.01 m (3.31 ft). Length: 9.12 m (29.92 ft). Propellants: Solid. No Engines: 1. Engine: Algol 1. Other designations: Senior. This rocket started as a Polaris test motor with a 40 inch diameter, which at the time was the largest solid motor ever tested. It had a nominal performance rating of 45 seconds duration and 45,000 kgf thrust. Variations included Algol I, I-D, II, II-A, II-B and possibly others. Another popular rating was 40KS-115,000 (52,000 kgf for 40 seconds), also known as Senior.

• Stage Number: 2. 1 x Stage: 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.

• Stage Number: 3. 1 x Stage: 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.

• Stage Number: 4. 1 x Stage: Altair 1. Gross Mass: 238 kg (524 lb). Empty Mass: 30 kg (66 lb). Thrust (vac): 12.450 kN (2,799 lbf). Isp: 256 sec. Burn time: 38 sec. Isp(sl): 233 sec. Diameter: 0.46 m (1.50 ft). Span: 0.46 m (1.50 ft). Length: 1.83 m (6.00 ft). Propellants: Solid. No Engines: 1. Engine: X-248.

1961 March 3 - Launch Site: Cape Canaveral. Launch Complex: LC18. Launch Pad: LC18B. Launch Vehicle: Blue Scout 2. Model: Blue Scout II. LV Configuration: Blue Scout II D-4.

• HETS A2-1 Plasma mission Nation: USA. Class: Earth. Type: Magnetosphere. Agency: USAF. Apogee: 2,540 km (1,570 mi). References: 5, 949.

• HETS A2-2 Plasma mission Nation: USA. Class: Earth. Type: Magnetosphere. Agency: USAF. Apogee: 1,931 km (1,199 mi). References: 5, 781.

• Mercury MS-1 Nation: USA. Program: Mercury. Payload: Radio Test Spacecraft. Class: Technology. Type: Tracking network. Spacecraft: Radio Test Spacecraft. Agency: USAF. Small satellite was to have verified the readiness of the worldwide Mercury tracking network. An attempt was made to launch Mercury-Scout 1 (MS-1) into orbit with a communications package further to qualify the radar tracking of the Mercury global network prior to manned orbital flight. Shortly after lift-off, the launch vehicle developed erratic motions and attending high aerodynamic loads, and was destroyed by the Range Safety Officer after 43 seconds of flight. No further attempts were planned. The Mercury-Atlas 4 (MA-4) mission and the successful Mercury-Atlas 5 (MA-5), flown on November 29, 1961, disclosed that the network met all requirements.References: 5, 126, 26, 483.

• McDowell, Jonathan, Jonathan's Space Home Page, Harvard University, 1997-present. Jonathan McDowell's complete on-line listing of all objects orbited and over 20,000 rocket launches Accessed at: http://www.planet4589.org/jsr.html.

• Koelle, Heinz Hermann,, Handbook of Astronautical Engineering, McGraw-Hill,New York, 1961. The only such comprehensive handbook ever produced, and at the dawn of the space age.

• Gatland, Kenneth, Spacecraft and Boosters, Iliffe Books. London, 1964. Survey of world launch vehicles.

• Parsch, Andreas, DesignationSystems.Net, . Outstanding, unique reference for aircraft, missiles, propulsion, and avionics systems. Accessed at: http://www.designation-systems.net/.