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Historical Essay © Andreas Parsch
Atlantic Research PWN-7 Rooster
The PWN-7A Rooster was a variant of the PWN-6 Kitty (Arcas) sounding rocket. Instead of a temperature transmitter, it used a ROBIN (Rocket Balloon Instrument) inflatable falling sphere as its payload. At the apogee of the probe's trajectory, a metalized balloon was released and inflated. While it was slowly descending back to earth, the balloon was tracked by a high-precision radar on the ground. Using the balloon's known mass and volume, the radar track could be used to calculate atmospheric data like wind speed-direction and air density. The latter could then be used to calculate air pressure and temperature.
Other than the PWN-6 radiosonde-equipped Arcas, the PWN-7A Arcas-ROBIN required a high-precision radar to get air temperature data. However, its altitude and temperature measurement ranges were somewhat greater than that of the PWN-6's instrument. The PWN-7A was replaced in the 1970s by the PWN-12A, the ROBIN variant of the Super Loki-Dart sounding rocket family.
SpecificationsNote: Data given by several sources show slight variations. Figures given below may therefore be inaccurate!
Data for PWN-7A:
| Length | 2.30 m (7 ft 6.6 in) |
| Diameter | 11.4 cm (4.5 in) |
| Finspan | 33 cm (13 in) |
| Weight | 33 kg (73 lb) |
| Speed | > 3950 km-h (2455 mph) |
| Ceiling | 65 km (40 miles; 210000 ft) |
| Propulsion | Atlantic Research SR45-AR-1 solid-fuel rocket; 1490 kN (336 lb) for 29 s |
[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] Frederick I. Ordway III, Ronald C. Wakeford: "International Missile and Spacecraft Guide", McGraw-Hill, 1960
[4] "Model Designation of Military Aircraft, Rockets and Guided Missiles", Department of Defense, 1970
AKA: PWN-7.