Directory of U.S. Military Rockets and Missiles
Copyright © 2002 Andreas Parsch

Cooper Development RM-88/PWN-5 Rocksonde 200

In 1956, the Cooper Development Corporation (CDC) received a contract for large scale production of sounding rockets of the Loki-Dart (PWN-1) type for use as weather research vehicles. This resulted in the Rocksonde (sometimes written as Roksonde) family of sounding rockets, of which several throusand were built in the following years. CDC offered two basic rockets motors, creating the Rocksonde 100 and Rocksonde 200 vehicle families, respectively. The former used the RM-2110 with 0.8 sec burn time for flights to about 30 km (100000 ft) altitude, while the latter had a RM-2210 motor with 1.9 sec burn time for altitudes up to 60 km (200000 ft). Darts of various diameters and different payloads could be custom-designed for each user.

Photo: via Morrow/Pines
Rocksonde 200 (PWN-5A)   (background: booster; foreground: dart)

The U.S. Air Force assigned the designation XRM-88 to a Rocksonde 200 variant with chaff payload. The XRM-88 could reach an altitude of about 60 km (37 miles), and the falling chaff was tracked by an AN/FMQ-6 ground-based wind-sensing system to obtain wind speed and direction data from high to medium altitudes. In June 1963, the XRM-88 was redesignated as PWN-5A. It continued to be used throughout the 1960s, but was eventually replaced as the USAF's standard low-cost weather rocket by the instrumented Loki-Dart (PWN-8).


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

Data for PWN-5A:

Length (incl. booster)2.64 m (8 ft 8 in); dart: 1.02 m (40 in)
DiameterBooster: 7.62 cm (3 in); dart: 3.49 cm (1.375 in)
FinspanBooster: 13.5 cm (5.3 in); dart: 8.6 cm (3.4 in)
Weight (incl. booster)13.4 kg (29.5 lb); dart: 2.7 kg (6 lb)
Speed6275 km/h (3900 mph)
Ceiling60 km (37 miles; 200000 ft)
PropulsionCooper Development RM-2210 solid-fuel rocket; 9.0 kN (2030 lb) for 1.9 s

Main Sources

[1] Frederick I. Ordway III, Ronald C. Wakeford: "International Missile and Spacecraft Guide", McGraw-Hill, 1960
[2] Norman J. Bowman: "The Handbook of Rockets and Guided Missiles", Perastadion Press, 1963
[3] Richard B. Morrow, Mitchell S. Pines: "Small Sounding Rockets", Small Rocket Press, 2000

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Last Updated: 27 October 2002