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Compressable airship/balloon

Change the volume of the airship/balloon to change upthrust
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Change the volume of a hydrogen or helium airship to control its altitude. Assuming the skin of the airship is made from flexible material, internally connect the front and the back end of the airship with ropes. Pull the ropes mechanically to change the volume of the airship. If a traditional balloon is used instead of an airship, the support ropes can be bunched together at the top of the balloon. This can be then pulled downward mechanically to change the volume. Of course bottom of the balloon has to sealed unlike a traditional balloon to prevent the gases from escaping.The airship/balloon will not have to carry ballast, use thrust vectoring or guide ropes to take off or land.
kneeslider, Jan 27 2010

A Girdle http://www.antiquek....com/equip01bak.htm
For [Wagster]. Involves changing the temperature. [pocmloc, Jan 27 2010]

Existing art - PV Stabilized High altitude balloon PV_20Stabilized_20H...0Altitude_20Balloon
[MisterQED, Jan 27 2010]

Compressable baloon drawing http://www.postimag...image.php?v=Pqh9ip0
[kneeslider, Jan 27 2010]

Prior Halfbaked Art Density_20ballasted_20airship
Internal balloons are squeezed to increase density, reducing lift. Sound familiar? [goldbb, Jan 27 2010]

Gravity Plane http://www.youtube....watch?v=0QZ1KzveIic
Apparently some Israeli thought of this seriously a few years ago [pashute, Mar 08 2010]

[link]






       Of course, use heat to change the density! I'm sure that hasn't been done before.
mitxela, Jan 27 2010
  

       I'll have to find the post, but I know I suggested a solar powered pump to pump excess hydrogen into a high pressure storage tank during the day to allow the envelope to survive solar heating cycles.
MisterQED, Jan 27 2010
  

       A girdle?
wagster, Jan 27 2010
  

       I found the post, which covers compression with a pump. If you want to compress using the existing envelope, you will need a heavy envelope. (-)
MisterQED, Jan 27 2010
  

       I should have clarified it a more. What I meant was- physically reduce volume of the airship. Assuming the skin is made from flexible material, internally connect the front and the back end of the airship with ropes. Pull the ropes mechanically to change the volume. No pumps are necessary. (I am editing the post to include this explanation)
kneeslider, Jan 27 2010
  

       Maybe a balloon made of wire mesh memory metal with a plastic liner.   

       Although I must admit there is an appeal to the idea of sweaty shirtless sailors girding their turgid dirigible with thick and bristly jute ropes. Put your backs into it, men!
bungston, Jan 27 2010
  

       [bungston] Somehow all of the adjectives in your second sentence seem to want to migrate to the left to modify the sailors.
hob, Jan 27 2010
  

       kneeslider -- you've left out an important requirement of the airship skin... not only must it be flexible, but it must also be inelastic.   

       The only material that comes to mind is mylar. Based upon personal experience, I would expect a mylar balloon, when squeezed firmly, to pop, before it appreciably compresses the air within.
goldbb, Jan 27 2010
  

       I was thinking of composite material. In case of the balloon, circumferential kevlar strings may be implanted into the fabric (not sure of what kind) to make it inelastic but still have the flexibility to pull the top down. You have probably already realized- the skin does not need to stretch or compress for the process changing the shape, so composites can be used to make the skin very inelastic.   

       Density ballasted airship is also a nice idea.
kneeslider, Jan 28 2010
  

       [pashute] love the link, especially this excerpt:   

       "Air from the atmosphere is compressed into the rigid shell of the aircraft to add weight. This is accomplished by using pneumatic motors driven by stored compressed air that powers air compressors."   

       umm...
FlyingToaster, Mar 08 2010
  

       I'd suggest you pick up a copy of The Mad Scientists' Club by Bertrand Brinley. One of the seven short stories, The Great Gas Bag Race, involves a similar premise. The members of the eponymous club devise a helium-filled balloon which they can adjust with a compressor, which wins them the "Hot Air Balloon" race at the county fair.
Alx_xlA, Mar 20 2010
  
      
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