Chris 540

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Me and my buddy wanting to each scratch build some huge profile planes. Were thinking about a 115" wingspan. We've been really thinking about this...

What are your thoughts on this????

Traxxas_Tech

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Ahhh...

I'll be scratch building an AW 330L profile this summer, You just gave me the idea to enlarge it while I'm at it.

Anyway...

You'll need to make your own plans, or enlarge at Kinko's a set you like. Make sure you enlarge it to a scale that you can use readily available sizes of wood. Fabricating your own sheeting and sticks gets real old real fast..

While youre at it, enlarge the control surfaces too.

majortom-RCU

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My thoughts are if I was a teen again and wanted to do something outrageous, I would work up to it gradually, by scratching a 60", then a 70", then an 80", and by the time I got to 115" I'd be the only expert in giant scale profiles and giving advice to others. I'm sure you can build one that will fly, assuming you have a Honda V4 to power it with, but a first model on that scale has to be regarded as experimental, and the method that works with experimental models is to advance by increments from known to unknown, not by giant leaps from wild speculation to got no clue.

One thing for sure, you're going to need to know your way around lightweight composite spars to fly at that scale.

This is the kind of objective a guy can get really excited about--but it's a lot more than a summer project IMHO.

(Just kidding about the Honda...i think...)

Steve_JR

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I am his friend that is joining in on it. We were going to use the ZDZ 80cc engine. I think we could go from 80" to 115" with not too much problem or even larger. We would have to add more ribs and work on the spar of course but it could be done. Oh and the profile we were thinking of using was actually the AW Extra 300L profile. -Steve

Traxxas_Tech

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The instructions for the AW profile suck, you are going to need to know without a doubt how the plane assembles.

I believe Morris Hobbies makes a 100"+ Wingspan profile, I have seen a huge profile at our field, They do exist, and they fly very scale like too.
And as noted above, knowlege of composites will be needed if you want to keep it in one piece in the air.

Good Luck

Chris 540

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Uhh..why??

Traxxas_Tech

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Ahem.... Use CF on parts you want to be stiff, Fiberglass on material you can have flexible, Use epoxy not CA. And if laminating sheets together press them together (use dead weight), so weakening air bubbles dont form.

I would use .60 oz-1oz CF veil on both main spars (top/bottom), or use 1/32 CF laminate strips lengthwise.

You can also wrap formers in CF tow, it adds ons of strength there...

I'm speaking from experience, everything above increased strength dramaticly.

Chris 540

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Anyone else??? Help!

majortom-RCU

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Now that I notice you and your building buddy are Maineiacs, I would increase my estimate of your chances of success by at least 100%. Maine farmboys have a great advantage in not knowing that things can't be done, so they just do them anyway.

Seeing as how you are still not discouraged, I will share with you a wonderful webpage, at http://users.ids.net/~bdfelice/Wedge-wing.htm. I cite this site because of the unusually effective trussed rib design. I was thinking if I were advising on your project, I would think this would be a natural for built-up laminated ribs, as opposed to cutting out balsa sheet. There are sites and documents here and there dealing with how to make a rib jig, build up each rib from strips of balsa, putting every gram of weight where it will do the most good, having all the grain bearing loads in the critical vectors. With a strong, light, composite reinforced laminated spar or two, plus stealing some of DeFelice's ideas on wing structure, plus built-up ribs, I think you could make a wing worthy of a giant profile.

What you learn making the wing could also be applied with suitable modifications to the fuselage. ZDZ 80 would probably be enough to make it fly creditably. Somehow I am thinking this could all be done with a 25 lb weight objective. In fact, I am beginning to think of this ship as made up mostly of carbon fiber, with just enough balsa to lend basic shape to the CF structure. Of course CF is only a couple hundred times more expensive than balsa, but you could save up enough for twenty pounds and leave the rest of the weight for engine and control system.

I was also inspired by the latest copy of RCModeler, article on fiber-optic control cable to handle long runs free of glitches. You would almost certainly want multiple servos in the tail to balance the powerplant.

Where is Hampden, anyway?

Chris 540

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Thanks a lot for your input!!

Hampden is just south of Bangor.. 5 Mins away from my house.

bestrcpilot

I have done a 100 inch Morris Knife.
So I say go for it.
The only place that I had to add some fiberglass was to the sides of the fuse where the wing tubes go. The rest of the fuse was just built up balsa. The wings are also built up balsa. The wing spars are made with 3/8 x 3/8 rock maple. I'm using two alum. wing tubes 1 inch od.
The plane came in at 17 pounds with a G-62 with tuned pipe.
Best 3D plane I have flown.
The plane has 800 flights on it as of this writing.
Scott Yeo