Engineers at Nasa’s Dryden Research Centre have recently flown an aeroplane with deployable, inflatable wings.
The I2000 radio controlled (R/C) aeroplane flew three successful flights. During the flights, the Dryden team air-launched the I2000 from an R/C utility vehicle aeroplane at an altitude of 800-1000 feet. As the I2000 separated from the carrier aircraft, its inflatable wings ‘popped-out,’ deploying rapidly via an on-board nitrogen bottle.
The Dryden team, consisting of Jeff Bauer, Jim Murray, Joe Pahle, Tony Frackowiak, Bob Allen, and John Redmond, now has data to verify and validate computer models of inflatable wings for the future. Each inflatable wing is 2.7 feet-long for a wingspan of just over five feet, not including the fuselage. In the undeployed stowed state, the wings fit in a container the size of a small coffee can. They began flying the I2000 with rigid wings having the same physical dimensions as the inflatable wings.
Wing deployment takes 0.33 seconds and utilises compressed nitrogen gas for the near-instantaneous inflation. A pressure regulator mounted on the nitrogen pressure vessel kept the internal pressure of the wings at a constant 200-250 pounds per square inch (psi), reducing the possibility of wing-sagging due to low internal pressure or high external pressure. The nitrogen tank was pressurised to 500 psi in order to allow excess gas to make up any pressure losses in the wings due to leakage.
With the I2000 flights completed, the Dryden team now aims to fly a four-foot long X-24A model with the inflatable wings by the end of summer in hopes of proving the concept of using deployable inflatable wings with lifting body vehicle configurations.
The X-24A shape was chosen because it has a well-established aerodynamic database. It represents lifting body vehicles in general, and, in particular, has upper body flaps for additional roll control.
The inflatable wings do not have flight controls, so the body flaps are critical for flight control. The I2000’s tail surfaces filled the gap on that standard configuration aeroplane.
The build-up to the inflatable wing X-24A flights will include flying the model with rigid wings first, the same procedure used for the I2000. Potential advantages of utilising inflatable wings on future lifting body vehicles include providing greater cross-range and lower landing speeds than totally wingless vehicles
Future applications of inflatable wings include earth science aircraft, any volumetrically limited aircraft, and planetary research aircraft.
A Helios-type high altitude, long endurance platform could conceivably carry multiple, small deployable inflatable wing aircraft to release as ‘probes’ to more closely investigate areas of interest located by the platform’s sensors.