Aviation Week & Space Technology
January 22, 1968
ppg 21
Hawthorne, Calif. --Use of electrical forces to condition the air flowing around an aircraft at supersonic speeds may lower drag, reduce heating and soften sonic boom, Northrop Corp., said here last week.
Although practical application of the technique, assuming research validates it, is quite far in the future, Northrop said its findings in company studies show enough promise to justify government funding of more intensive research, NASA is reportedly interested in the method.
Air molecules ahead of the aircraft would be ionized, probably negatively, through a corona. The nose of the aircraft would be charged to the same negative potential, forming an electrostatic force field which would tend to repel or alter the course of the molecules as the aircraft approached.
Preliminary work has been largely analogous, using liquids rather than air. However, limited wind tunnel work has established that the corona dishcarge readily propogates forward in a Mach 3 airstream with no measurable attenuation due to the air flow.
The work has been conducted by M.S. Cahn and G. M. Andrew of the Norair Div. Cahn and Andrew were to report their results Jan. 22 to the sixth Aerospace Sciences Meeting of the American Institute of Aeronautics and Astronautics in New York.
Company officials are guardedly optimistic about the usefulness of the technique because of the preliminary stage of the research.
Next stage in the research requires expenditure of roughly $100,000 to modify a wind tunnel with electrical insulation. This would create isolated conditions similar to those of an aircraft in flight. Work in Northroup's 5 inch tunnel failed to produce meaningful results when the electrical discharge applied to the test body grounded against the walls of the tunnel.
Northrop officials concede that communications problems would arise in a charged aircraft, but pointed out that a solution might be found in the method used to maintain communication through the plasma sheath of a spacecraft during re-entry.
In a possible application for the technique, the nose of the aircraft would have to be insulated from the rest of the vehicle to preclude charging the entire airframe, Cahn believes. The excess electricity could be discharged through a trailing boom into the slip-stream, which would act as a ground.