|Directory of U.S. Military Rockets and Missiles|
|Copyright © 2002 Andreas Parsch|
The PWN-12A is another sounding rocket using the Super Loki booster of the PWN-10 and PWN-11. It uses a dart with a ROBIN (Rocket Balloon Instrument) Inflatable Falling Sphere payload. At an apogee of about 115 km (70 miles), the dart releases an ML-568/AM metalized mylar balloon, which is inflated to 1 m (3.3 ft) diameter and 12 hPa pressure. While it is slowly descending back to earth, the balloon is tracked by a high-precision radar (e.g. AN/FPS-10) on the ground. Minimum tracking altitude is about 30 km (18 miles), where the ambient pressure will cause the balloon to collapse. Using the balloon's known mass and volume, the radar track can be used to calculate atmospheric data like wind speed/direction and air density. The latter can then be used to calculate air pressure and temperature.
Other than the telemetry-equipped PWN-10 and PWN-11 probes, the PWN-12A ROBIN requires a high-precision radar to get air temperature data. However, its maximum altitude and temperature measurement ranges are greater than that of the datasondes. PWN-12A rockets (also known as Super Loki Inflatable Sphere) were used at least until 2000 on NASA and military stations for regular high-altitude weather probing.
Note: Data given by several sources show slight variations. Figures given below may therefore be inaccurate!
Data for PWN-12A:
|Length (incl. booster)||3.15 m (10 ft 4.5 in); dart: 1.11 m (43.7 in)|
|Diameter||Booster: 10.2 cm (4 in); dart: 4.1 cm (1.63 in)|
|Finspan||Booster: 20.3 cm (8 in); dart: 11.7 cm (4.62 in)|
|Ceiling||115 km (70 miles; 380000 ft)|
|Propulsion||Aero Dyne SR110-AD-1 Super Loki solid-fuel rocket; 25 kN (5520 lb) for 2.1 s|
 Richard B. Morrow, Mitchell S. Pines: "Small Sounding Rockets", Small Rocket Press, 2000
 "DOD 4120.15-L: Model Designation of Military Aerospace Vehicles", Department of Defense, 1974
 Upper Air Instrumentation Research Projects Website, NASA [Note: Rocketsonde file is no longer online!]
 Edward J. Hopkins: "Meteorological Rockets", 1996 (originally at http://earthlab.meteor.wisc.edu/~hopkins/rockets/metrockl.htm, now dead link)
 ORDATA Online Website
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