Slashdot Mirror
MIT and NASA Designing Silent Aircraft
Iddo Genuth writes "Researchers at the Massachusetts Institute of Technology Department of Aeronautics and Astronautics recently won a contract from the National Aeronautics and Space Administration to design quieter, more energy efficient, and more environmentally friendly commercial airplanes. The two-million-dollar contract from NASA is just an initial step in bringing green technologies to the sky."
It's called a balloon.
These aircraft will be silent, but deadly?
Sorry, just had to sneak that in...
Enclosed engines? That is not going to be as easy to maintain as the 'drop off' ones that currently sit under the wing.
After all we've already had the "Whisper Jet." Of course anyone who's heard a 727 take-off knows that that is a relative term;-)
If brevity is the soul of wit, then how does one explain Twitter?
"Silent" is a relative term, but the presumption is one that has noise levels approaching that of an automobile.
That simply is never going to happen. Moving air around to create thrust will always be noisy. Even if all engine noises are reduced to zero, the vibrations of the air moving at the extreme speeds we would expect will cause more than enough noise. The only way I can imagine to combat that fact would be to distribute the effect over very large areas... and even then, as the size of the air moving system approaches "too big to be practical" it would still likely be way to noisy.
Helicopter style systems would be more of the same.
They are going to go back to Roswell and Area-51 and figure out how the aliens did anti-gravity so we can have aircraft that fly with less thrust requirement.
Didn't hear it coming neither!
Nobody ever thinks of us poor runway maintenance folk when designing their 400ton aircraft :(
which is totally what she said
I don't see how efficiency can go down because noise and efficiency go hand in hand. Noise is caused by air turbulence, reducing air turbulence will increase efficiency.
Having said that, two million is a drop in the ocean for this sort of thing. How come the USA can spend trillions bailing out stupid bankers but only has a couple of million for this sort of thing?
No sig today...
Here's a picture of the prototype.
No folly is more costly than the folly of intolerant idealism. - Winston Churchill
I'd put many smaller, distributed brushless electric-motors all along the wing, especially towards the wingtips.
In order to help increase lift based on pressure (active pressure differences), I'd place the propeller centers below the wing, rather than above the wing.
To counteract some of the loss of lift from wingtip vortex pressure losses, I'd make the propellers spin with the bottoms moving towards the fusilage.
In order to reduce explosion risk, I'd use Lithium-ion phosphate batteries.
I'd probably also have to have a very long aspect ratio for the wing, so the plane wouldn't be flying all that fast.
But it could be done, and be economical (in terms of cost per flight hour, cost per mile) too. It wouldn't be economical for someone who wanted to go from here to there fast.
So if you were an automobile executive who wanted to declare that your company was about to go bankrupt unless you got a few spare billion (and then declare that bankruptcy is not an option if you don't get it), you'd have to use a lear jet instead, preferably retrofitted with a zillion pulse jets. But they make a tad more noise, and use a tad more fuel.
Different economic situations require different answers, I guess.
Correct Horse Battery Staple: 72 bits of entropy. Enter "Correct H" into google. When it generates the phrase, that's
wonder if CA will try to pass a law making these jets have a noise generator so that the blind can hear them coming (you know like their trying to do with eletric cars)
'...if only "Jumping to a Conclusion" was an event in the Olympics.'
This is research money. In my understanding of the term, that means that the money is to be spent to try and find solutions that don't exist today. They might succeed, they might fail. Even if they succeed, there's no guarantee that the research will make it into a commercial product. That is true of all research. Furthermore, I don't see any comments that substantiate the vaporware tag. Shouldn't it be a requirement that if you're going to add a tag to an article you have to add a comment too?
Sure, they will never be silent, but they haven't been doing much improvement in the last 30 years. The old 707 engines were remarkably loud - going to turbo-fans made a big improvement, but I feel like they haven't made any further reductions since the "hush kits" of the late 1970s.
The entire Florida peninsula is severely noise-polluted from aircraft. Even when they are flying over at 30,000 feet, they're louder than the breeze in the trees, or an idling car engine, 6' away. If they can reduce the sound output to where the noise from a jet at cruising altitude is less than normal ambient noise in a suburban neighborhood, that would be a big accomplishment. I doubt they'll get it down to where you can't hear them while standing in a quiet field away from air-conditioners noise of passing cars - but they can try....
Also, don't forget the military aspect of this - F4 Phantoms were intimidating, but they certainly wouldn't sneak up on anyone, even if the person was deaf they could feel an F4 coming. F16s are a huge improvement, noise wise. I've never heard a stealth fighter in person, but I assume their noise signature could be reduced too. A fighter jet capable of silent approach and supersonic response speeds would have plenty of applications.
tm
Support TBI Research: http://www.raisinhope.org
The noise an airplane makes at its home base doesn't count. The noise it makes over an enemy position in the night does.
rj
Better yet, how about a silent leaf blower. Far more annoying IMHO.
It's about time that the stolen UFO technology currently being used in silent black helicopters is finally trickling down to private enterprise.
Have you ever been on the ground when a B-2 is flying over? It's insanely quiet even at low altitudes. It's accomplished via an insanely simple method too. The exhaust is vented on the top side of the plane, so it does not resonate downwards as much.
CA is not "trying" pass a law that would make electric cars have noise generators (it doesn't even makes sense to talk about a state "trying" to pass a law: an interest group might lobby a state for a law, but that's not the state trying anything.)
California rejected (the legislature passed and the governor, citing that the issue was appropriately handled at the federal level, vetoed) a bill that would create a study to committee to determine what the sound requirements were for the safety of the blind around quite vehicles and to investigate means of meeting those requirements.
Presumably, the findings on this could have been used in the future to support legislative proposals for requirements, if both sound types levels which provided notable safety benefits and reasonable means of meeting those were determined; they just as easily could have provided fuel to support the argument that the necessary sound levels would have other adverse effect, be unreasonably expensive, etc., against such a future proposal.
It's true that in many places, in the East Coast and in California, advocates for the blind have lobbied for requirements for noise generators (not just study of the issue), but that's very different from any particular state passing (or even "trying to pass") a law requiring that.
Gliders are near silent, and are aircrafts !
the governor, citing that the issue was of paramount import for stealth in the imminent rise of the machines, vetoed
There we go, fixed that for you.
which is totally what she said
The airlines could care less about noise, comfort, and environmental impact. If it saves them some gas then it may fly.
Maybe that's all we had left after bailing out the bankers? :-P
A marriage is always made up of two people who are prepared to swear that only the other one snores.
Are a paranoids wet dream, cloaked black helicopters in whisper mode are already following me everywhere I go, I know they're there because I don't see or hear anything, really!
I killed da wabbit -Elmer Fudd
Fairly large numbers of people are killed by internal combustion cars, even with all the noise they make; anything that addresses that will also address the safety of quieter cars, and given that for the foreseeable future cars that usually move with an engine running are going to far more common than those that don't, will probably provide vastly more public benefit for the same amount of effort.