1296. Small Ship-Based VTOL Aircraft: A Design Exercise

Paper

Abstract

A design exercise was performed to examine a number of moderate performance VTOL aircraft, other than the AV-8, which could be based aboard small ships in the mid-to-late 1980’s. Configurations were to have a takeoff gross weights about 20,000 lbs (9000 kg) with minimal external stores. The vehicles were designed to perform only vertical takeoffs and landings; no conventional or short takeoff and landing capability was required. The design mission consists of a simple high-altitude cruise and loiter profile; no combat or high-g maneuvering requirements were imposed.
Current high-bypass-ration engines were studied as possible effective power plants for a pure VTOL aircraft. Unfortunately, the cruise efficiency of these engines was more than offset by the hover control problems inherent in the engineers due to gyroscopic effects. Designs using low bypass engines of the appropriate size were also examined. Although some attractive layouts were obtained, these required the use of lift engines which will not likely be available during the desired time period without a substantial immediate funding commitment.
For a number of reasons, including performance level, availability, and cost, uprated versions of the Rolls Royce Pegasus-11 engine gave the most reasonable solutions. Of course, a funding commitment would also be required to make uprated version available. Efforts were taken to exploit the vertical-only takeoff/laning and the low g requirements to assure that the resultant configuration was simpy a styling change for the Hawker Siddely AV-8A.
The basing of aircraft aboard small ships also presents haul ddown and securing problems, but solution to these appear to be written the state-of-the-art although they will require some engineering effort.
A lightly-arm reconnaissance vehicle in the 20,000 lb (9,000 kg) class having a radius of approximately 300 mi (555 km) appears feasible, provide that the mission requirements remain simple; any multmission or high performance requirements would immediately result in increased size and weight.