Scratch built Sport craft flies - RC Groups
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Feb 20, 2003, 12:11 PM
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Scratch built Sport craft flies

Well, its made of foam, and I'll be flying in parks and schoolyards, but I thought the Sport crowd might like to see it. It doesn't have a name yet; seems to look a bit like a 4*40 with maybe some Extra mixed in. Mid wing design allows for convenient equipment installation with the battery above the wing and other stuff below the wing.


Wing, 40 in., 360 sq. in.
Wt, 26 oz
Power, Mega 16/15-3, 3.27:1, 10x5E, 150W
Batts, 10-Max1000's

I have only flown it briefly so far due to some kind of motor cut-out problem, but it is very stable, and slows down well for landings. Haven't done much aerobatics yet.

It was a very quick build, even without any plans. So when I destroy it I won't cry too much. Next time I'll try to raise the turtle deck a bit and make the nose a little sleeker.

Seems like these materials have been used mostly for making oddball sorts of planes like flying pizza, etc, but it seems to be just as good for conventional sport craft.
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Feb 20, 2003, 12:37 PM
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Mark Sanders's Avatar
Looks great Bob, Well done.

Please can you give a little more info on construction ?
eg what spar(s) are used in the wing? and reinforcing in the fuz ?

Thanks Mark
Feb 20, 2003, 12:44 PM
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GaryK's Avatar



Nice looking scratch project!

What current are you drawing on your setup? I'm not familiar with the batteries you mention and perhaps you are exceeding their ability to put out the amps required. Give us more details and I'm sure the group can help you figure out the cut off problem you describe.

Feb 20, 2003, 12:58 PM
Registered User
Well, first of all, there was not a lot of thought put into this, so its certain there are improvements to be made. The weak spots may begin to show up as I stress it more.

The wing is blucore fan-fold foam, simply folded over a spar of the same on edge; then a hard balsa spar was added in about the middle third of the wing. Then packing tape was added top and bottom. It feels pretty strong.

The fuse sides and turtle deck are folded up from one piece of the blucore. The top of the nose is a carved and shaped block of 1/2 inch thick foam. Bottom is more blucore. This way, the ugly edges and seams are on the bottom. The only additional structure is behind the motor mount where I sheeted the inside of the fuse with 1/32 ply, and used some spruce to connect things together. It all feels very rigid, except right behind the wing, where it could use a bit of ply in the right places.
Feb 20, 2003, 01:07 PM
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The batteries are 1000mah Nimh cells, very similar to the HE 1100's. I have some KAN950's on the way, which are the same size with lower resistance. 15 Amps is about all the max1000's will deliver, but its only needed for verticals.

The speed control is a Castle Creations Phoenix 25, and the receiver is a Berg (5 channel?) on 50 MHz. I'll put in a different receiver first and see what happens. Seems like it happens only at altitude, which seems like radio interference, although this seems unlikely. It will just require some swapping things around to find the cause.
Feb 20, 2003, 08:35 PM
Registered User
One question;

This plane requires a lot of right rudder on take offs to keep it straight. Is this just because there's a lot of torque, or is it caused by some other design factor. Is there any way to reduce this effect?

I already have a bit of right thrust.
Last edited by Bob Baker; Feb 20, 2003 at 08:42 PM.
Feb 21, 2003, 05:42 AM
KOMET 44's Avatar
Bob sounds like you need more right thrust in your motor.stefanP
Feb 21, 2003, 03:53 PM
Registered User
It seems to me that if I put in enough rt thrust to compensate for torque during takeoffs, I'll have too much after I get up to speed; does this make sense?

Does the tail dragger configuration have anything to do with it? The only two planes I have had that do this were tail draggers.

I suspect I just need to learn how to fly it and force it to behave.
Feb 21, 2003, 03:59 PM
It's just PLANE silly!
balsaman's Avatar
Most tail draggers need right rudder for takeoff. This is normal, and you get used to it quikly.

Very nice airplane. Don't change a thing!


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