PWN-8 (original) (raw)

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PWN-8

Part of Loki

American sounding rocket. In the early 1960s, the low-cost Loki-Dart sounding rockets could only carry a passive chaff payload to high altitude. For more sophisticated payloads like temperature transmitters, the USAF had to use the significantly more expensive Arcas. The Space Data Corporation (SDC) was founded in 1963 with the goal to develop a meteorological instrument package small enough to fit into the 3.5 cm (1.38 in) diameter darts of the Loki-Dart systems.

Historical Essay © Andreas Parsch

Space Data PWN-8 Loki Datasonde

In the early 1960s, the low-cost Loki-Dart sounding rockets (PWN-1, PWN-5) could only carry a passive chaff payload to high altitude. For more sophisticated payloads like temperature transmitters, the USAF had to use the significantly more expensive Arcas (PWN-6 Kitty) rocket. The Space Data Corporation (SDC) was founded in 1963 with the goal to develop a meteorological instrument package small enough to fit into the 3.5 cm (1.38 in) diameter darts of the Loki-Dart systems.

SDC designed an instrument package which would be released from the dart at high altitude and descend slowly below a square metalized mylar parachute structure called "starute". A circuit with a thermistor (temperature-sensitive resistor) would continually transmit temperature data to the ground station. Altitude information was obtained by tracking the descending starute by radar. The rocket motor of SDC's Loki-Dart was based on the Rocket Power Inc. "Judi-1" design, and assembled by Aero Dyne Corporation. Because the original Loki-Dart was only marginally stable in the motor burnout phase, SDC built slightly heavier darts, which decreased the apogee by about 3000 m (10000 ft) but significantly enhanced the stability, and therefore reliability, of the system. SDC's instrumented Loki-Dart was qualified for production in 1966, and more than 20000 units were built until production ceased in 1985.

The initial Air Force variant of the instrumented Loki-Dart was the PWN-8A, but the main USAF version was the PWN-8B. Because it was significantly cheaper than the PWN-6 Kitty (Arcas), the PWN-8B quickly replaced the latter for many every-day routine applications. The PWN-8B itself was eventually replaced in USAF service in the early 1970s by the larger Super Loki family (PWN-10, PWN-11, PWN-12) of sounding rockets. SDC marketed the rocket as the Loki Datasonde(r), which is sometimes referred to as PWN-8D. This is an unofficial designation, with the D suffix possibly chosen to mean "Datasonde".

Specifications

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

Data for PWN-8B:

Length (incl. booster)	2.95 m (9 ft 8.3 in); dart: 1.24 m (49 in)
Diameter	Booster: 7.62 cm (3 in); dart: 3.49 cm (1.375 in)
Finspan	13.7 cm (5.4 in)
Weight (incl. booster)	15 kg (33 lb); dart: 4.3 kg (9.5 lb)
Speed	?
Ceiling	60 km (37 miles; 200000 ft)
Propulsion	Aero Dyne SR71-AD-1 solid-fuel rocket; 9.55 kN (2150 lb) for 1.9 s

Main Sources

[1] Richard B. Morrow, Mitchell S. Pines: "Small Sounding Rockets", Small Rocket Press, 2000
[2] "DOD 4120.15-L: Model Designation of Military Aerospace Vehicles", Department of Defense, 1974

Country: USA. Agency: Aerojet.

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