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Old Jul 26, 2012, 09:56 AM
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Resources - Big Bubble Dancer-like Glider

hello friends;

recently, my friend has suggested that we build a 5m AVA or a Bubble-Dancer-like electric glider (for those of you in the know, it's actually a commercialized Bubble Dancer available on Hyperflight.)

out of craziness, I have decided to go along with the idea and see how far it takes us...

I have recently started sketching up the basic outline on sketchup and generated the profiles

you are free to have them as well = )

please ignore the pdf names.... it's actually designed for foam core, with glass.

our idea is that we would use blue foam covered with 1mm balsa skin and glassed for ding resistance.

it'll be electric, too, with a 3 piece wing.

for strength, we could add internal spars.

any opinions or suggestions from experienced builders would be welcome, I think you guys have built more gliders than I have = )

right now, I'm just thinking - lightweight fibreglass on the inside of the balsa skin, and lightweight fibreglass on the outside.

I have a space saver bag and a hand-pump as well, that might do a crude form of vacuum bagging....

think it'll work?

anyway check back, this might take some time....

oh by the way, the layout is based on the XCBD.....



edited..... wing panel 4 is now corrected
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Last edited by Sunfire; Jul 30, 2012 at 10:24 AM.
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Old Jul 26, 2012, 12:13 PM
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United States, MA, Waltham
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I haven't built many bagged wings, and those were sheeted, but I've helped bag some full scale boats, and I find myself using my vacuum pump reasonably often for this and that.

There is no "could" about the spars, especially with the wing construction you are proposing. This is a long, skinny wing. If you were willing to use a fair amount of carbon, it might make sense to go with a slightly higher aspect ratio. If I'm not mistaken, you're at something like 19:1. The XBCD has an aspect ratio of 18.5.

On a project of this magnitude, don't try to skimp on the vacuum pump. Whether it is homemade or commercial, you should have a decent amount of vacuum (20" Hg on the gauge, perhaps) and a good amount of flow.

If you don't want to skin with carbon or glass with no balsa, maybe thin aircraft ply, grain on the diagonal, would be a good alternative.
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Old Jul 26, 2012, 08:19 PM
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There is no "could" about the spars, especially with the wing construction you are proposing. This is a long, skinny wing. If you were willing to use a fair amount of carbon, it might make sense to go with a slightly higher aspect ratio. If I'm not mistaken, you're at something like 19:1. The XBCD has an aspect ratio of 18.5.

Hi Lincoln, thanks for the reply.

so you mean to say, a spar is definitely needed? I would guess so, esp for middle panel. noted....

we traced this out from the XCBD's profile.
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Old Jul 26, 2012, 08:30 PM
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Im the other crazy partner in this endeavour.....I get to do the 2.4m long fuselage.

I have previously made stuff out of Medium glass/balsa/medium glass with no bagging...and it came out weighing a ton. So this time round we definatley need to bag. Carbon rovings int eh right places for reinforcement.

Sparing for the wing is a must. Since the center panel is rather flat. We could cut a channel for a balsa carbon sandwhich with joiner tubes at the end. Wing sections capped with thin ply to mount the locating pins and joiner tubes.

We could get inspiration from vladimir

http://f3j.in.ua/en/supra-el-family.html#fussupra
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Old Jul 26, 2012, 08:42 PM
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Glass is heavy and flexible, though it's strong. For high aspect ratios and large spans, I think carbon will help a lot.

If you want to save money, maybe light glass and disser skins? (Disser, apparently, is a bunch of tow laid up on the diagonal at intervals.)

Lots of info on various build threads and on the plans at charlesriverrc.org. I think there's even a thread on the XCBD
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Old Jul 28, 2012, 07:35 PM
Whisper Model Aircraft
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Greensburg, PA
Joined Feb 2008
558 Posts
You might follow along with Curtis.

Thats the simplest, cheapest, most successful build I've seen.

http://www.rcgroups.com/forums/showthread.php?t=1528685

Will
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Old Jul 30, 2012, 12:01 AM
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cheapest and most successful! Wow! I am in!
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Old Jul 31, 2012, 05:41 PM
WINS - Winch In Nose Sailplane
jaizon's Avatar
USA, NH
Joined Mar 2008
3,086 Posts
Here you go, guys. A 4.8M Supra like glider.
http://www.rcgroups.com/forums/showt...9#post22317724

I have seen this version (and prior ones) fly.

Very cool.

Contact John if you are interested in getting all kinds of valuable info.

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