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Old May 28, 2005, 12:20 PM
Stuck on a rock
epilot's Avatar
Faroe Islands, Sandoy, Sandur
Joined Nov 2000
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Hans, you might want to look up some human powered aircraft on the internet. This will give you some idea of how to construct a light model. IIRC the HPA that crossed the English Channel used blue foam ribs. I would suggest using carbon fibre for the spars to keep weight low. Some years ago I saw articles about a giant C-130 model that crashed because of spar failure. I'll see if I can dig up some details.

Michael
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Old May 28, 2005, 12:27 PM
Around the World
cadconversions's Avatar
Scottsville, KY
Joined Jun 2002
5,641 Posts
Going to keep an eye on this one for sure.
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Old May 28, 2005, 12:36 PM
Registered User
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Hawaii, Kauai Wailua
Joined Jan 2004
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hehehe if i had the money and didnt live in hawaii i would buy it in a second hehehe
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Old May 28, 2005, 12:38 PM
Lance Armstrong- 7 times!
flybike's Avatar
Madison, Wisconsin
Joined Sep 2001
1,335 Posts
Hi Michael,

That's good advice about the human powered aircraft- they are really incredible machines. I thought about carbon spars, but they are too expensive. I ripped up the floor of an old house a while ago. To my surprise, the floorboards were sitka spruce. I kept the boards. The grain is very tight and straight. I think I'll cut these up for the spars.

For this plane I'm going with a simple two piece wing. Each panel will be about 23 feet long and will plug into the fuselage. Of course, this means it will never travel anywhere.

Anyone have ideas for supporting the outer panels of a polyhedral wing with flying wires? I could do the whole thing without wires and it would look great, but it would be much heavier, so I'm using wires.

-Hans
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Old May 28, 2005, 12:44 PM
Stuck on a rock
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Faroe Islands, Sandoy, Sandur
Joined Nov 2000
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Wood will be OK but then you should consider WW1 building techniques and use some sort of wire bracing like you suggest yourself. Keep it simple and avoid polyhedral. You might even make a semi-scale model of a Fokker E3 Eindecker

Remember to check that the wing will handle both positive and negative g-loads.

A bit about the Herc here: http://www.rcgroups.com/links/index.php?id=3315
A lot smaller than you are gunning for

Michael

PS: Make sure you check with FAA before flying a model this size. You could find yourself in some serious legal trouble if you are not careful.
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Old May 28, 2005, 12:53 PM
Stuck on a rock
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Faroe Islands, Sandoy, Sandur
Joined Nov 2000
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Another thought: I think you will find it difficult to reach an AUW of 60lbs. When you double size, weight increases by the square (roughly speaking). You would need to look at using a light covering like Mylar instead of sheet foam for the wings. Spruce spars, foam ribs and mylar covering will work.

Michael
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Old May 28, 2005, 01:45 PM
Stupied User
PupSocket's Avatar
wretched hive of scum and villianry
Joined Apr 2005
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Quote:
Originally Posted by epilot
You might even make a semi-scale model of a Fokker E3 Eindecker
Wow, would that be a larger-than-scale size?
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Old May 28, 2005, 01:59 PM
Lance Armstrong- 7 times!
flybike's Avatar
Madison, Wisconsin
Joined Sep 2001
1,335 Posts
Does anyone make lightweight, low rpm propellers somewhere around 60 inches in diameter?

Also, does doculam come in 48 inch rolls? The widest I've seen is 27. This would probably be the cheapest way to cover the plane. A clear covering with a wooden structure would look nice.
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Old May 28, 2005, 02:19 PM
Stuck on a rock
epilot's Avatar
Faroe Islands, Sandoy, Sandur
Joined Nov 2000
5,885 Posts
Actually Mylar would be cheaper and lighter. See if you can find a company that makes bags for potato chips or similar. They use mylar by the truck load and they might have a damaged roll you can get for free. I have gotten a lot of mylar this way. You save the weight of an awful lot of adhesive. Can't help with a prop but UL planes come to mind. Realistically you are looking at building something similar to a UL plane if it has to be airworthy. Only difference is that you don't need to carry the weight of a pilot. Good luck with the project!

Michael
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Old May 28, 2005, 02:55 PM
Boffin
rpage53's Avatar
Victoria, BC, Canada
Joined Apr 2001
3,397 Posts
Covering

Doculam is narrow to fit laminating machines and you have to carry around the extra adhesive. But there are lots of other polyester films around (Mylar is one brand name). The famous Gossamer Condor was mylar over wire-braced aluminum tubes.
http://www.nasm.si.edu/research/aero...ead_condor.htm

Check out the Tyvek that is used for buildings -- cheap and heat shrinkable. It comes in many thicknesses and widths. Its polyolefin.
http://graphics.dupont.com/en/produc..._special.shtml

You can also laminate Tyvek to foam to strengthen bulkheads. Reemay is the brand name of a similar spun-bonded polyester. Its sold as landscape fabric. You can probably get all the material you need free as scrap from housing contractors and landscapers.

You can also use polyester or nylon cloth from the fabric store. Its still heatshrinkable and when you paint it (you can use varnish) it becomes stiff. But no matter what you use, you'll need to try some mockups to determine what the actual strength is. An airframe of 50 lbs is barely feasible.

Good luck,
Rick

PS I see Michael had the same idea about Mylar while I was looking up references. Of course, if you just want to make a FloydX2 you don't really want to change the construction method to save weight.
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Old May 28, 2005, 03:04 PM
Formerly of mcba fame
Matthew Allen's Avatar
Luxembourg
Joined Apr 2001
3,007 Posts
Quote:
Originally Posted by Usta Bee
My nomination for test pilot .......


flybike,

Lots of people on this forum pretend to be mad (count the threads with crazy in the title) but you may just about qualify. That is SOOOOOO cool.

Matthew
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Old May 28, 2005, 03:05 PM
Lance Armstrong- 7 times!
flybike's Avatar
Madison, Wisconsin
Joined Sep 2001
1,335 Posts
You can heat shrink Tyvek? Crazy... I'll have to try it.

I dont know what I was thinking when I said 50 lbs- it will be heavier than that.

Thanks guys, this is helpful stuff. I'll look around for covering, but if anyone has links, I'd be happy to see them.

-Hans
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Old May 28, 2005, 03:38 PM
Striving to Rip the Bring
raptor22's Avatar
San Diego, socal, USA, North America, Earth, Solar System, the Orion arm, Milky way, Universe
Joined Apr 2003
6,320 Posts
Hey, if anyone gets to ride it, it should be me

At our local aerospace museum, we have the world's smallest man carrying aircraft. I beleive it is 15' in span , nd the rider would lay on the back.

--Alex
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Old May 28, 2005, 04:16 PM
29 rods from you in western WI
Karl Bē's Avatar
Joined Jan 2003
4,885 Posts
Quote:
Originally Posted by raptor22
we have the world's smallest man carrying aircraft. I beleive it is 15' in span
That's small, but nowhere near as small as the Bumblebee.
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Old May 28, 2005, 07:30 PM
HeliAP'er!
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Surrey, UK
Joined Aug 2003
8,210 Posts
He's at it again! I look forward to seeing whatever you come up with - get everyone behind you with donations as well. If things get too out of hand with the donations you may even end up making a profit from this gargantuan machine!
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