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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."

17 of 176 comments (clear)

  1. It's called a balloon. by Anonymous Coward · · Score: 5, Funny

    It's called a balloon.

    1. Re:It's called a balloon. by VeNoM0619 · · Score: 4, Interesting

      Only 2 million...? For a new plane design?

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    2. Re:It's called a balloon. by Thanshin · · Score: 4, Funny

      Or a slingshot.

      Catapult?

      Ballista?

      Trebuchet?

      Mankind can't consider itself advanced till we can send satellites to space using a trebuchet.

    3. Re:It's called a balloon. by SimonTheSoundMan · · Score: 5, Funny

      What I thought. My last university spent £2m getting one of the campus buildings into Second Life.

    4. Re:It's called a balloon. by inviolet · · Score: 3, Insightful

      Catapult?

      Just so you know, 'catapult' is the category of all heavy leverage throwers. Onagers and trebuchets are catapults; slingshots are not; ballistas, being composed of two small opposing onagers, might be ("paracatapult"?).

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  2. So, you're saying... by liquidMONKEY · · Score: 5, Funny

    These aircraft will be silent, but deadly?

    Sorry, just had to sneak that in...

    1. Re:So, you're saying... by CRCulver · · Score: 4, Funny

      Yes, you'll know them by their vapour trails, but you won't hear them coming.

    2. Re:So, you're saying... by GooberToo · · Score: 4, Informative

      The prop tips on these airplanes reach transonic speeds at full power

      Prop designs are tailored for a specific aircraft design and engine combination. Part of the requirement for prop selection is to avoid supersonic or even transonic speeds, even while at full throttle. The reason being, efficiency significantly falls off once a prop begins to reach transonic speeds, let alone supersonic speeds. It is so important to avoid these speeds, well, you now know the origin of the scimitar shaped prop.

      In short, if you are flying any Cessna 185, 206 or 207 which has a prop reaching transonic speeds, your prop needs to be replaced as it has been overhauled too many times.

  3. Engine maintance costs. by Zebadias · · Score: 4, Insightful

    Enclosed engines? That is not going to be as easy to maintain as the 'drop off' ones that currently sit under the wing.

    1. Re:Engine maintance costs. by actionbastard · · Score: 3, Funny

      "...the 'drop off' ones..."

      Oh, I hope not!

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  4. Jet tehcnology can't do it ever by erroneus · · Score: 4, Informative

    "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.

  5. Re:Silent... aircraft. Huh. by Amouth · · Score: 3, Funny

    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)

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  6. About time... by JoeMerchant · · Score: 3, Insightful

    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.

  7. Black Helicopters by ZirbMonkey · · Score: 4, Funny

    It's about time that the stolen UFO technology currently being used in silent black helicopters is finally trickling down to private enterprise.

  8. Re:Silent... aircraft. Huh. by DragonWriter · · Score: 3, Informative

    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)

    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.

  9. Re:Silent... aircraft. Huh. by somersault · · Score: 4, Funny

    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
  10. Black helicopters in whisper mode.. by Paracelcus · · Score: 3, Funny

    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!

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