Eastern Airlines doesn't really like to call its brand new A-300 Airbus an airbus because the term seems to lack dignity when trying to sell flights. So Eastern ha srenamed the two-engine European-made jumbo jet it is introducing to the U.S. the A-300 Whisperliner.

That's just part of the hard sell for the A-300 that Eastern brought yesterday to Dulles Intenational Airport even though Eastern has no plans for flying the airbus to Dulles.

Eastern actually wants to land its jumbo at Washington National Airport - where jumbos are prohibited - and that's what yesterday's exercise was all about even though none of the Eastern and Federal Aviation Administration officials wanted to come right out and say so.

They were gathered at Dulles along with reporters, TV cameramen, representatives of area citizens' committees concerned with jet roar and noise technicians from local governments.

The guests got to stand on the runway at Dulles (nobody has done that in such numbers since the Concorde first landed 19 months ago) and listed to the A-300 take off and land. It was without question the quietest thing going and FAA sound measurements prove it.

Then the visitors were taken on a pleasant 90-minute flight down the Blue Ridge, across the James River Valley, up the Eastern Shore and back to Dulles and fed shrimp cocktail, lobster, steak, wine, coffee and liquors.

"We tried not to leave any stone unturned," Eastern vice president James E. Reinke said after the affair yesterday.

How much did it cost Eastern?

"Maybe $5 a dinner . . . I don't have the figures here, but that was better than the average meal you would get in tourist . . . Maybe it was $6 a meal . . . We might even be talking about $7 a meal," he said. There were about 100 people aboard.

The A-300 Airbus is manufactured by a European consortium operating as Airbus Industrie. Airbus has been vigorously secking an American buyer after three years of success in Europe and elsewhere.

Eastern is trying out four of the Airbuses for six months, and has an option to purchase them and more at the end of that time. Beginning Dec. 13, those four planes will be used on Eastern's profitable mid-winter run between New York and Florida.

Eastern has outfitted each plane with 229 seats, 203 of them in coach. if such a plane were dropped into the Eastern shuttle between New York and Washington "it would scoop up what three DC-9s would carry," Reinke said.

Eastern orginally asked to demonstrate the A-300 at Washington National, officials confirmed yesterday, but the FAA was more than a little reluctant to permit that and stir up once again the noise issue.

The Federal Aviation Administration, which runs both National and Dulles, is under a court order to produce an environment impact statement on the effect of planes using close-in National.

That statement, in its final stages of preparation is expected to address the jumbo jet issue in a series of options ranging from closing the airport (which nobody really thinks will happen) to expanding it dramatically (which nobody really thinks will happen).

There is enormous citizen pressure from both sides of the Potomac River to do something to reduce the impact of jet noise from planes using National.

One proposal, from the Metropolitan Washington Council of Governments, is to get airlines substitute one jumbo flight fortwo regular flight - thus keeping the airport capacity even but decreasing the noise. The airlines already limited by quotes to about 69 flights per hour (not counting extra sections) are unalterably opposed to that. But they are not opposed to using jumbos.

The fact is - and Eastern set out to prove it yesterday - that the newer wide-bodied jets are quieter than most airplanes using National today. The A300 is the quietest yet, according to FAA measurements.

Steve Newman, an FAA noise specialist who has fought ticks in dense underbrush near Dulles and battled angry citizens in New York City to measure Concorde noise, took some quick readings yesterday and said that the A300 measured at "3 to 4 times quieter than a (Boeing) 727 at a point 3 miles from the end of the runway.

There are two main reasons.The a300 is powered with only two engines. All other jumbos have at least three engines. The new jumbo engines are in themselves quieter than the old engines that propel most 727s.

Secondly, because of its configuration, the A300 has a very high angle of climb - it gets higher quicker and thus puts less noise on the ground. A veteran airline pilot at the demonstration yesterday marveled at the fact the A300 nose lifted off the runway on takeoff after the plane rolled only 1,800 feet. "That's remarkable," he said.

John Stiffler, Eastern's manager for sales and service at National and Dulles, said that Eastern terminal facilities at National can handle the passengers and baggage for five Boeing 727s or two a300s simultaneously.

"What's going to sell this airplane." Eastern vice president Michael J. Fenello told the visitors yesterday, "is your perception of the noise."

Then Eastern got a break. As the crowd poured on the runway to listen, Air Force One (really a four-engine Boeing 707) roared off noisily on a practice takeoff. It was followed closely by a very quiet Whisperliner.

"That's really impressive," said Dr. Robert J. Cunitz, chairman of the Montgomery County Noise Control Advisory Board. CAPTION:

Picture 1, Stewardess prepares to serve Michael Fenello, Michael Wall and James Davis in front seat of Whisperliner., By Larry Morris - The Washington Post; Picture 2, A 300 Airbus, called Whisperliner by Eastern Airlines, lands quietly at Dulles., By Larry Morris - The Washington Post