The RP-99
The design study and proposal for a small surveillance drone called the RP-99 were completed in March 1962. This vehicle was to be constructed of fiberglass panels bonded to paper or phenolic honeycomb cores.
The RP-99 was to be powered by a McCulloch MC-20, 9-hp engine which drove counter-rotating propellers through a gear box. Air speeds of 200 knots (371 km/hr) at sea level and 195 knots (361 km/hr) at 15,000 feet (4572m) were estimated for this drone. A unique, spring-wound mechanism was proposed to launch the RP-99. Two 0.33-KS-610/T53 E1 JATO boosters also could be used to launch this vehicle. A parachute was used for recovery.
A mock-up of the Northrop Ventura RP-99 was constructed in 1962, but no test or production drones were ever built by Northrop. The design of the RP-99 was sold to the government of Belgium, which fabricated several drones inspired by Northrop’s design. The Belgian drone is known as the Epervier (Sparrow-Hawk), and the X-1 version is powered by a Wankel engine. The X-2 and X-3 versions have Hirth piston engines, while the X-4 uses a Rover TJ125 turbojet for propulsion. The Epervier has a wing span of 5.8 feet (1.8m), a length of 7.1 feet (2.2m), a height of 2.5 feet (0.76m), and a weight of 214 pounds (97 kg).
