JPL RM-82/PWN-1 Loki-Dart

The Loki-Dart was a very popular low-cost sounding rocket of the 1950s and early 1960s. It was developed from the Army's abandoned Loki anti-aircraft rocket, and sounding rockets using the "boosted dart" principle of the Loki-Dart are still in use today.

When the Loki anti-aircraft rocket was cancelled, this was not the end for the Loki rocket. In 1955 the U.S. Navy had the idea to fill the dart with chaff instead of an explosive warhead. Launched almost vertically, the dart was carried to high altitude where the chaff was released. By tracking the falling chaff by radar, accurate measurements of high-altitude wind speed and direction could be obtained. In the following years, Loki-Dart sounding rockets with the original JPL rocket or newer improved motors were widely used by civilian and military customers. The USAF allocated the missile designation XRM-82 to a Loki-Dart variant with a JPL-132A motor and a chaff-filled dart. The XRM-82 was launched from a tube-launcher, could reach an apogee of 55 km (180000 ft), and was used by the Air Force in the late 1950s and early 1960s. The U.S. Navy used Loki-Dart type rockets known as Loki-Wasp and HASP.

Photo: via Morrow/Pines Loki-Dart (XRM-82)

In June 1963, the XRM-82 was redesignated as PWN-1A. At that time, however, there were already more advanced Loki-derived sounding rockets available, and the PWN-1A was probably no longer used by the mid-1960s. Advanced developments of the basic Loki-Dart, which were used by the U.S. military services, included the Cooper Development Rocksonde (PWN-5), Space Data Corporation's instrumented Loki-Dart (PWN-8) and Space Data's Super Loki-Dart family (PWN-10, PWN-11, PWN-12).

Specifications

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

Data for PWN-1A:

Length (incl. booster) 2.63 m (8 ft 7.5 in); dart: 1.02 m (40 in) Diameter Booster: 7.62 cm (3 in); dart: 3.49 cm (1.375 in) Finspan Booster: 12.7 cm (5 in); dart: 8.6 cm (3.4 in) Weight (incl. booster) 13 kg (29 lb); dart: 3.2 kg (7 lb) Speed 6275 km/h (3900 mph) Ceiling 55 km (34 miles; 180000 ft) Propulsion JPL 132A solid-fuel rocket; 9.0 kN (2030 lb) for 1.9 s

Main Sources

[1] Richard B. Morrow, Mitchell S. Pines: "Small Sounding Rockets", Small Rocket Press, 2000

[2] Peter Alway: "Rockets of the World", Saturn Press, 1999

[3] Redstone Arsenal Historical Information Website



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Last Updated: 9 March 2005