Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: THURSDAY, June 16, 1994 TAG: 9407120062
SECTION: EXTRA PAGE: 1 EDITION: METRO
SOURCE: Joel Achenbach
DATELINE: LENGTH: Medium
A: We called British Airways to find out what a round-trip jaunt to London on the Concorde would cost, and they told us, in a flat tone of voice that suggests years of training so as to avoid cracking up, $7,800. We offered to stay over a Saturday night. They still wouldn't budge.
So there's part of your answer: Supersonic flights didn't catch on because most people, rather than parting with $7,800, would sooner attach chunks of raw bleeding meat to their limbs and swim across the Atlantic.
The Concorde, though a technological triumph, is old. It's 1960s technology. It only holds about 100 passengers, because it's a thin, sleek plane. And it has a range of only about 3,000 miles. Even that distance requires 200,000 pounds of fuel, half the weight of the entire plane. Adding significantly more fuel isn't possible because the plane would be too heavy.
With so few passengers the Concorde has a high operating cost per ``passenger mile.'' And the short range means it can't fly the increasingly popular Pacific routes, which require a range of closer to 6,000 miles.
But here's the headline: Supersonic travel is about to have a renaissance, though it will still be limited to transoceanic flights. Numerous U.S. and European aircraft makers have already come up with designs for planes that can fly up to Mach 2.4, about 1,600 miles an hour. Right now it takes 10 hours to fly between Los Angeles and Tokyo, but with supersonic planes it would take only 4.
Randy Harrison, a spokesman for Boeing, says his company has come up with a design for a plane that could carry 300 passengers in three classes. It'll be 311 feet long, compared to only 231 feet for the Boeing 747.
There are two problems: First, plane exhaust can damage the ozone layer at the altitude where supersonics cruise, around 60,000 feet. Second, the new generation of supersonic planes need to be quiet as they come in and out of airports at subsonic speeds. Ideally the engineers will also find a way to dampen the noise from the sonic boom. Lou Williams, director of high speed research at NASA, says engineers want to find a way to make the shock wave from a supersonic plane less organized, so the noise is not so explosive and startling.
``What we're trying to do in terms of softening the noise is turn it from a shotgun into a thump,'' Williams says.
In other words, not so much a sonic boom as a sonic thud.
The Mailbag:
Joe S. of Miami, Fla., writes with an interesting observation: We're always told the moon affects the Earth's tides. But Joe points out that astronauts are weightless just a couple of hundred miles above the Earth's surface. So, he figures, gravity is pretty weak at that distance. And the moon is much smaller than the Earth and much farther away, so he reckons its gravity pull should be weaker still. ``Is it possible,'' asks Joe, ``that scientists are mistaken about the moon's effect on our tides?''
Dear Joe: You are mistakenly thinking of the Earth and moon as being sucking instruments that act on inert bodies. The fact is, gravity isn't a one-way process. It's an interaction between two bodies. To calculate the gravitational attraction between two objects you have to plug in the mass of both objects. The moon is able to influence the Earth's tides not only because the moon is a large object but also because the ocean is so massive. The ocean pulls on the moon too!
Another mistake you make is assuming the astronauts aren't affected by Earth's gravity. They are, and that's why they and their spacecraft don't go winging off into space. Gravity and inertia conspire to create the spacecraft's orbit.
But for the record, we do like the thought that maybe the tides are caused by the twitching of continents.
Washington Post Writers Group
by CNB