aeajr

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I think I am finally going to fly my first SPAD; I think. If it is made of green building foam board as opposed to coro plastic, is it still a SPAD?

Anyway, assuming it is, here is what I am working on. If I can figure out how to post a photo I will.

I have a plane made of green foam board 24" wide by 29" long including 4" elevons. It is a profile plane that also includes a fin and rudder above the board and a profile fuse above and below.

It is a flat board with just a big rounding of the nose that starts at the center and curves toward the sides till it hits at 12", so it is a 12" radius curve.

The whole plane weighs 5.5 oz.

I plan on attaching a GWS 350C motor with D gear box giving me a 6.6 to 1 ratio. According to GWS this motor on 8 cells and a 10X4.7 prop will produce 17.85 oz of thrust.

I have two GWS naro+ servos (.35 oz), one for each elevon. I also have a GWS Pico F for the rudder (.2 oz) I have a micro 5 channel receiver that I estimate at .35 oz and a 20 amp speed control at .5 oz. The motor weighs about 2.5 oz. Total about 4.25 oz.

So, all up weight without the battery should be about 9.75 oz.

I have an 8 cell 1100 mah 4/5A pack that weighs about 6.5 oz taking me to 16.27 oz. vs 17.85 of thrust drawing 9.3 amps.

I am now going to make an 8 cell pack out of AAA 800 mah cells that should come in around 4 OZ taking the total weight to about 13.75 oz vs thrust of 17.85 oz.

So here are my questions:

1) I hope to be able to hover the plane with either pack. Do the numbers seem to work, or am I being overly optimistic.

2) Where should I try to set the initial CG? I was thinking about 40% back form the nose since the plane is all wing, but the wing is rounded up front.

3) Should I try to put the servos near the control surfaces to minimize control rods or should I center them along the length of the plane to be more balanced and incur less wire?

4) Push/pull or pull/pull?

How am I doing?

Any other suggestions or tips would be appreciated. I really have very little idea of what I am doing.

novabill

Looks cool.

I think 11-12 oz is ideal for that combo. many people are using 2 and 3 cell Li-Pos with the gws gear drive. If I'm not mistaken, a two-cell 1200 mah li-po weights appx 2.5 oz.

As far as the balance, ??? but with a delta you need it farther back.

I think I would use micro pushrods and lite-ply horns glued into the foam.

William

ChrisSpad

you'll want the cg no more than about 22% mac. I'd just figure the overall chord, and set the cg at 22% of that to start, then move it back a bit at a time till you get a good hover.