Marin

Has anyone tried displacing the air in a built up wing with helium, trapping it in the covering to reduce wing loading on a floater, or park flyer, or for that matter on a larger sailplane? :bananahead:

MTT

My Feedback: (8)

I thought Fool's day was April 1st ! ??????

BMatthews

On the off chance that you're serious it won't work. Helium leaks out through the pores in the covering material and would be gone in less than a month. And besides, the model still has all that mass that has to be turned. And finally the volume of a typical wing won't make diddly difference even when freshly filled with helium. It's all just an old model wife's tale....

The right way to do it is to adopt the ways of the free flight monks and learn to build light in the first place...

steve-kerry

Helium molecules are smaller than nitrogen or oxygen molecules, so they will leak out through the plastic covering. To get around that you need to cover the wing with mylar or something similar. While there is plenty of merit in tissue and mylar covering, it still wouldn't be completely airtight so you would need to keep topping it up!

Grab a calculator and work out how many cubic feet are displaced by your wing. For a very convenient figure, say 12" chord and 120" span. That's 10 sq ft of area, and again for convenience say your average airfoil thickness is just over an inch so you get about one cubic foot of displacement. Actually it will be a bit less due to spars and wing sheeting. How much lift will you get from one cubic foot of helium? A 2M wing will only contain half that volume.

More importantly, if you do manage to stop it leaking through the covering, can you be sure it will be evenly distributed? If your wing has dihedral the helium will gather at the tips because they are higher, so if one tip develops a tiny leak then it will be heavier than the other tip! A minor scrape on landing would be enough to lose all the helium without you realising it, too.

And if you want ailerons or spoilers in your wing, you need to keep them airtight from the rest of the wing but still have them fully functional including having access to the linkages.

Bottom line: it's not worth it! Learn to build light wings in the first place

Psssniper

My Feedback: (3)

Metalized mylar will contain the helium for a while anyway.
Example would be the balloons at the supermarket.
Or you could build your model from Unobtanium, the lightest strongest material unknown to man.

bjaffee

Just tie the model to a bunch of balloons, let it float up to a good height, then release it.

Rob Glover

That's why we use vacuum bagging to build composite wings. A vacuum is even lighter than helium. Just get yourself a vacuum pump and suck all the air out of your Gentle Lady and you won't even need a high start to launch.

Elroy Jetson

FLYBOY

My Feedback: (11)

I like the baloon idea too. Put places on the spar to tie them, and put about 6 per side, and launch. You will never have to come down, or turn, or change pitch, or ......

vtol_guy

also with the helium, when you think about it, the same volume would probaly fill that of an average sized balloon, i've never known a balloon to carry any more than about 5grams of blu tack

you could always try hydrogen...no....DONT!!

dedapr

How about say a 10' surplus weather balloon on a 300' line staked to the ground. Attach the glider w/ a servo release tow hook?

Everyone in the club could use it all day by hoisting it down & then letting it do the work of a hi-start!

In any event it beats helium filled wings!!!

Tall Paul

A cubic foot of air weighs 1.22 oz.
How many planes enclose foot of air, including the fuselage and tail?

FLYBOY

My Feedback: (11)

All I know is our blimp is 12 feet long and 6 foot wide and full of helium. Takes that much to lift the motors, gondola and radio. You won't get enough in the wing of a glider to even know it is there.

rogerflies

My Feedback: (3)

I once saw an ultralight plane with inner tubes stuffed in the wings to keep it from sinking if it crashed in the water.

And my point is.....???

steve-kerry

How much does a cubic foot of helium weigh? It's the difference between the air and the helium that will provide any lift in that respect. The only way to get the full 1.22oz of lift is with a cubic foot of total vacuum...

ronrange

My Feedback: (20)

I 've been using Heli-spheres, helium filled micro-ballons, for years to lighten structures. No reason why these coulld not be used to fill in the empty spaces in a built up wing.

:>)

steve-kerry

I tried to order some heli-spheres once, but we could never get the postage sorted out. Since they weigh less than zero, I insisted the post office should pay me instead of the other way around. They disagreed for some reason, so it was never delivered. Six months later a postal inspector looked into the case, and opened the packet. I believe the heli-spheres are still on the ceiling of his office, because nobody knows how to get them back down and put them into the container again.

Adudein

My Feedback: (11)

A guy once told me I should cover my Gentle Lady with black covering as it would heat the air inside the wing resulting in a lighter glider.Kind of a "hot air balloon" theory.

He was serious,I could hardly keep a straight face.




Yeah,I did

Miami Mike

If gases separated into layers according to their respective weights, then our atmosphere would be split into separate nitrogen and oxygen layers, wouldn't it?

Strat2003

My Feedback: (1)

Yeah, with CO2 on the bottom (gasp, choke)