Slashdot Mirror
Towards Silent Supersonic Planes
Roland Piquepaille writes "There is no longer a single commercial supersonic airplane since the retirement of the Concorde last year. And even during its years of glory, the Concorde was not a commercial success, mainly because it was not allowed to cruise at supersonic speed over land. Why? Because of the sonic 'boom' which arises when you break the sound barrier. Now, a joint program between NASA, the military and the aerospace industry wants to remove, or at least reduce, this sonic boom, by changing the shape of supersonic planes. It seems to work. After a 'nose job' on a Northrop Grumman F-5E, about a third of the pressure released when breaking the sound barrier has already been suppressed. This overview contains more details. It also includes a photograph of the modified Northrop Grumman F-5Ea aircraft flying off the wing of the F-15B research testbed aircraft. [Note: Previous results were reported here by Slashdot in last September.]"
The concorde was EXTREMELY expensive to operate, so even if it was allowed to travel supersonic anywhere it wanted, it still would have failed. airlines are cutting every cost possible in an effort to undercut each other, so the concorde's death was just waiting to happen.
Sure, if you don't mind the fact that you'd consequently have most of your thrust directed downward... you know - for every action there's an equal and opposite reaction, etc, etc.
A supersonic nosedive is not for the faint of heart.
People care more about the cost and security of air travel. It was never about the sound (although that didn't help), it's just down to the cost of fuel and limited range of the craft.
Sure, the sonic boom wasn't too good, but that never stopped the US Air Force from flying their supersonic planes day in and day out over populated areas. I still remember periodic sonic booms over Tucson (from a nearby base) as well as over Seattle whenever Boeing was testing their latest SS jet fighter.
Let's face it, the main reason the Concorde wasn't allowed to fly over the US is because it wasn't US made.
The short answer is "yes"
.The long answer is "yes, but it's proving to be very difficult."
It used to be that the primary cause of (commercial) jet noise was the engines. Manufacturers have managed to reduce the acoustic output from the engines (somewhat :) through engineering and operation changes (see here for example).
Other challenges include aerodynamic noise and structure-borne noise. Aerodynamic noise reduction can hopefully be achieved through shape changes. Structure-borne noise is a little difficult because it's difficult to mitigate without adding weight to the plane.
My personal feeling is that structure-borne noise reduction can be accomplished using active-vibration reduction, but then again, I'm more of a surface-transportation noise-guy than an aero/astro noise guy.
This is an interesting project that could improve the future of supersonic travel, but what is really needed (as with almost any technology just coming to the general market) is to bring the price down. There is certainly a market to speed up oversease flights (such as California to Japan) and a cheaper supersonic plane could really do a good business.
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Thank you.
I think you are right that a combination of new technologies might lead to economical supersonic travel.
If we compare flying to taking the train on the basis of fuel economy then it is obvious that we should give up flying. Taking the train uses much less fuel per passenger mile. Taking a ship takes even less. Clearly, other things matter more than fuel economy. I can't afford to send an employee from New York to Los Angeles on the train.
Done right, a quick flight between London and Tokyo might well be more cost effective than a slower flight even if the airfare is more.
The other thing that made the Concorde expensive was that it held relatively few passengers. A very large plane flying at high altitude would certainly have different economics.
"the Economist thinks it likely that Boeing will be out of the civil aviation business entirely in ten years time" Well, certinally they will, because we all know that they aren't selling any planes right now, and it'd be impossible for them to develop any new planes out of composite materials with quieter engines. Oh yeah, there's no way things coule possibly turn around for them.
Some of us don't care whether reported technology is immediately practical. We visit .\ for entertainment; for us "nerds," that often means science news that's cool or interesting, regardless of the technology's maturity. We don't visit .\ to learn about how to improve our lives, though sometimes we do learn such things. We visit it for fun.
A lot of intriguing stories are for our own mental enrichment; an external reward is not necessary. They're not time wasters (in the fundamental sense) for us when they grant to us what we desire.
If you only want to read about the big events that affect standards of living, I suggest CNN.
If it was profitable, they would be still in service.
The range wasn't adequate for non-stop trans Pacific routes. On these long distance routes where Mach 2 speed would be most advantageous, they needed to stop and refuel. That quickly negates the time savings. The 747 and other subsonic trasnports had long range versions, which could make the same trips non-stop.
Other than the national airlines of the two sponsoring governments, British Airways (BOAC) and Air France, no commercial airline ever bought a Concorde. If the business case was there, the planes would have sold on their merits.
Both Boeing and Lockheed had SST development programs in the early 60s. Boeing proposed a swing-wing design (like the F111, F15, and B1), while Lockheed had a double-delta (like the XB70, SR71, and Concorde). As soon as Congress pulled the plug on federal subsidies, both these programs ended. The companies involved sold many 747s and L1011 jumbo jets, profitably and with far less taxpayer subsidy than Concorde.
Without massive subsidies from the British and French governments, Concorde would never have been. So kindly spare me the "protectionist" drivel! Was it an engineering feat Yes! Was it presitigious? Yes! Did any company ever see fit to produce an SST using their own money? NO!