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Old Sep 05, 2002, 03:21 PM
The Zirconia Kid
LongRat's Avatar
Charfield, Nr. Bristol, UK
Joined Aug 2002
106 Posts
Easy weight loss?!

I've been thinking about this for some time, but with no intention to try. What if you strategically placed foil bags into an airframe, and filled them with helium. I would imagine it would only be beneficial on larger planes, but the apparent reduction in weight might be interesting. Of course, inertial mass would not be decreased, so no benefit there, but general flying and taking off may be improved - once the correct CG has been reached! I can just imagine a 1/3rd scale Extra flying on a speed 400... J/K!

LongRat
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Old Sep 06, 2002, 04:05 PM
jlk
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Chicago & Tucson
Joined Sep 2001
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It's not even April 1.

Seriously, the difference in density between helium and air is not as great as you might like or believe. Ever notice how large the envelope is on a blimp, model or full size. The weight saving for all your trouble in a large model would not amount to the weight of the bag to hold the helium.

There was an April fool article many years ago, I think in the old Model Builder Magazine about a program to make micoballons in space that would be filled with helium and would weigh negative. So the more filler you used the lighter your plane would become.

Jordan
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Old Sep 06, 2002, 04:11 PM
jlk
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Shame on you longrat. I just read your bio. You are a physics student.

Homework, calculate the interior volume of a two meter wing with a 1/3 meter cord and 15% thick. Then find the difference in the weight of the mass of air and helium.

Jordan
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Old Sep 06, 2002, 04:14 PM
jlk
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By the way, my son is a physics and math major at Stanford University.

Jordan
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Old Sep 06, 2002, 08:05 PM
Will work for planes
omega blood's Avatar
Fullerton, California, United States
Joined Jan 2002
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inflateable wings ?

I think NASA is actualy working on Inflateable wings. They have an actual working bird that gets droped from a mother ship seconds later the wings inflate. I don't remember what gas they used to fill the wings but I don't think it was helium probably Co2.
The article sugested future use on mars due to the compact size.
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Old Sep 06, 2002, 08:12 PM
RIP Ric
Andy W's Avatar
Marietta, GA
Joined Jun 1999
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To the original question, the amount of helium you'd be able to contain within a typical wing structure would be negligible compared to the overall weight of the airframe.
..a
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Old Sep 07, 2002, 12:08 AM
Gravitationaly Challenged
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La Canada, CA USA
Joined Oct 2000
354 Posts
Hey, I just had an idea.
This lighter than air, gas thing could work.
Since filling the wings with helium would not provide enough volume to provide lift
why not increase the size of the fuz and fill it with bladders filled with helium or better yet hydrogen, it's even lighter.
Yeah, then you won't need wings, just a long fat tube for a fuselage. Put some fins on the rear with rudders. A couple of motors, one on each side, and off you go.
yours truly, Herr von Zepplin ;-)
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Old Sep 07, 2002, 01:19 AM
Registered User
Colonial Heights, Virginia, USA
Joined Mar 2001
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we could at least fill the tires up with hydrogen gas...real big tires.......... kw
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Old Sep 07, 2002, 03:29 AM
I "plant" trees (balsa)
Gary Retterbush's Avatar
Eisenschmitt, Germany
Joined Jan 2002
777 Posts
Are we sure who and what is full of gas here?????
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Old Sep 07, 2002, 04:23 AM
The Zirconia Kid
LongRat's Avatar
Charfield, Nr. Bristol, UK
Joined Aug 2002
106 Posts
Ha ha ha ha!

I knew this would stir up some interest! I hadn't bothered to calculate the volume of a typical wing/fuselage, but I mentally figured it would need to be large to make a difference, hence I said about larger planes. Without having a vast experience of model aircraft, I really don't know the difference caused to the flight performance of planes when a certain amount of weight is removed. Therefore, I posed the question.

Maybe helium is too close to the density of air to be of any benefit, but.. I have felt the weight of a balloon filled with pure xenon. Man, you would not believe it was a gas at all - felt like it was full of water or something. But no sloshing!
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Old Sep 07, 2002, 12:36 PM
Will work for planes
omega blood's Avatar
Fullerton, California, United States
Joined Jan 2002
1,783 Posts
I have often thought of this. I called it the derigiwing. A fling wing concept frame work filled with gas bags. Like a derigible only in the shape of a wing to increase the speed and reduce the drag.
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