An old means of propulsion may power the commercial airliners of the future, if the National Aeronautics and Space Administration is successful in redesigning the propeller.
NASA is developing propeller blades with a curved design that makes the turboprop engine it plans look something like a window fan. Unlike the old design, the tips of this propeller will be able to go at supersonic speeds, NASA says. That will allow it to push a commercial-sized aircraft quietly at about the same speed as today's jet engines.
But the main attraction of the newfangled prop will be its ability to conserve fuel. NASA predicts the new planes will be able to achieve high speeds while saving nearly 40 percent of the fuel that today's jets use.
''Propellers are just a more efficient way of producing thrust,'' said Paul Johnson, manager of NASA's advanced turboprop program. ''Compared to the aircraft of today, it would be a 35 to 40 percent improvement in fuel efficiency. Compared to the advanced jets now being designed, it would save 15 to 20 percent.''
NASA is working on the propeller design because aircraft manufacturers could not risk the money or time to develop such an untested system, Johnson said. It hopes to have a research aircraft ready before the end of the decade, he said, and then private aircraft manufacturers can decide if they want to make a commercial model.
''It's up to NASA to show the concept is feasible,'' he said, ''so that the manufacturers can put up the big money to develop the aircraft.''
While much of the rest of NASA's budget is being trimmed, Johnson said Congress is interested in accelerating work on the new turboprop. The House Committee on Science and Technology asked NASA to prepare a report on what would be required to advance the project by two years.
Developing the plane would cost the federal government about $200 million, Johnson said, and between $30 million to $40 million will be required in the agency's 1983 budget.
Johnson said the airline industry has ''lobbied long and hard'' before congressional committees to push the turboprop's development, but some industry spokesmen sounded less than enthusiastic.
''At this point, there's no indication that it will be to our advantage to switch over to it,'' said Delta Air Lines' Richard Jones. ''We will watch it closely, and evaluate the advantages and disadvantages. We are concerned with the speed of the aircraft - if it will be fast enough.''
A spokesman for McDonnell Douglas Corporation, one of the nation's leading aircraft builders, said that while the fuel efficiency numbers looked favorable for the new turboprop, ''The problem is getting an engine to power something that large (as a modern commercial aircraft).''
And at Pan American World Airways, Bill Hibbs, director of Research and Evaluation, said he was not looking forward to the return of the propeller engine.
''It would have reliability and design problems,'' he said. ''I would expect it would have a terrific number of mechanical bugs. The problems we had with the old propellers were fantastic.''
But Johnson said that after four years of development NASA has successfully tested a scale model of the new propeller in wind tunnels. He said the agency is ready for the next step of building and testing a larger model that should be completed in 1985.
Even if the tests are successful, however, the new aircraft will probably not be carrying passengers any time soon. Airline industry predictions range from the mid-1990s to 2020 before an advanced design turboprop could be in wide use.