Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The Gravity-Powered Aircraft

  1. Jul 31, 2010 #1
  2. jcsd
  3. Jul 31, 2010 #2

    Jonathan Scott

    User Avatar
    Gold Member

    They seem to have skipped over the fact that it needs energy and/or additional supplies of compressed air and/or helium to be able to change the buoyancy in a cyclic pattern.
     
  4. Jul 31, 2010 #3

    russ_watters

    User Avatar

    Staff: Mentor

    In principle, it's just an overly complicated sailplane, so there is no violation of physics, but it seems awkward to call a sailplane a "gravity powered airplane", even though it kinda is.

    Operating without thermals, though, would not be possible.
     
  5. Aug 3, 2010 #4

    Office_Shredder

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Not awkward at all. Clearly a method of performing a smooth transition of cash from an investor's pocket to the inventor's pocket.
     
  6. Aug 3, 2010 #5

    mgb_phys

    User Avatar
    Science Advisor
    Homework Helper

    There used to be an Air Force saying that when the weight of the contract paperwork exceeded that of the airframe - the plane would fly.

    Perhaps that's what they mean by gravity powered?
     
  7. Aug 15, 2010 #6
    I think one of the posters at the end of the article nailed it. It was an April Fools joke.
     
  8. Aug 15, 2010 #7

    loseyourname

    User Avatar
    Staff Emeritus
    Gold Member

    This is just a combination of a hot-air balloon and a feather.
     
  9. Aug 16, 2010 #8
    It would take more energy compressing and releasing the gas than it takes to scoot it along via jet fuel.
     
  10. Aug 17, 2010 #9
    Ha! I love that quote, its so true.
     
  11. Sep 7, 2010 #10
    I say it is nothing but just hot air
     
  12. Sep 8, 2010 #11
    I believe you're correct.

    One proposal I'd like to see fully examined is a study on the variation of airframe designs between traditional airframes to fully-suspended airframes.

    Questions:

    1. Is there even a break-even point, or are fully inertial-supported airframes the answer? Seventy years of improvements in commercial aviation seems to indicate that the goal of getting the cargo from point A to B is best served by conventional means i.e. the latter. But that preliminary conclusion seems to be based on a time expectancy (getting pax or cargo to destination in a shorter time - air shipments overseas still cost way more than ground/sea).

    2. Various http://en.wikipedia.org/wiki/Ground_effect_vehicle" [Broken]have not only demonstrated serious advances in efficiency, even over high-altitude cargo craft, but certainly over train or roadway transportation which either have not or cannot be built.

    Personal case in point: I wanted to visit a friend in England in 2009, and was living in Germany at the time. Chunnel? Too expensive. The sleeper ferry then in existence (it probably still is) was more akin with my budget, but for travelling just a few hundred km, was way beyond what I could afford to expend.

    Anything involving going over the Channel at that time blew my budget totally out of the water.

    Yet... I could afford to fly over the entire Atlantic ocean, at will, to see my son, at least once each year, and for significantly less.

    I don't know what to say, except consider it as an input.
     
    Last edited by a moderator: May 4, 2017
  13. Sep 8, 2010 #12

    FlexGunship

    User Avatar
    Gold Member

  14. Oct 31, 2010 #13
    I’m no master of physics but may I make an observation as a man of limited brain power, to me it should be called an Troposphere submarine as it uses ballast tanks either side to rise and fall much the same way as a submarine does with the added advantage of wings to alow it to glide once it reaches the height needed for flight
     
  15. Oct 31, 2010 #14
    obiously submarine is descriptive of its position below water so in this case it should be called a subtroposphere machine if you get my drift
     
  16. Oct 31, 2010 #15
    one more thing if they just pumped the helium back out of the ballast tanks into a compression tank increasing its density possibly even into liquid form venting the ballast tanks underneath to allow air to fill the tanks controlling its weight not so much a hot air balloon more a helium controlled glider
    Sorry if I am spouting rubbish as I said before I know nothing of physics.
     
  17. Nov 1, 2010 #16

    FlexGunship

    User Avatar
    Gold Member

    [*]There is merit to your idea; the problem with gases that are significantly lighter than air (i.e. helium) is that they tend to permeate most surfaces (sic. mylar balloons); it is not a closed system.

    Edit by Ivan
     
    Last edited by a moderator: Nov 1, 2010
  18. Nov 1, 2010 #17
    I agree helium is lighter than air just as air is lighter than water in submarine ballast, so it means you obviously need the right density of material as not to allow the helium to escape.
    so as you rightly pointed out due to its porosity a skin from a helium balloon is no good, but I’m sure in this age of complex alloys, Thermoplastics and thermosetting polymers a skin could be found that is both light and dense enough as to contain the helium effectively enough as to create a closed system or closed enough to be a viable option.

    Again please forgive my feeble attempts to speak on this subject as I am uneducated never passed an exam in my life (could not even pass a blood test lol).
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: The Gravity-Powered Aircraft
  1. Hypersonic Aircraft (Replies: 16)

  2. What aircraft is this? (Replies: 10)

Loading...