Designs

[blue cobra]

If I'm going to offset my stab, in which direction should it be offset?

[jander14indoor]

Tail offset. Think of it this way. Look at a long train from the top as it goes around the curve. The engine in front makes an angle to the caboose in the back. Thighter turn, more angle. It has to do this or you get increased drag.

This is what your plane is doing, think of the wing as the engine, the tail as the caboose. For minimum drag, each flying surface should be aligned along a radius of the circle the diameter your plane is flying. For typical circles inside a gym, the tail will be offset about a quarter or half an inch from along the line of the motor stick. Since these planes turn left best, the tail boom, and tail, should be offset to the left as you look at the plane from the top. Looking from front that will be to the right, from the rear, the left of course.

Jeff Anderson
Livonia, MI

[blue cobra]

I'm sorry, when I said offset I meant moving it along a line parallel to the wingspan. In other words, mounting the posts on the stab a bit off center. I haven't seen this on any plans though, so maybe it's not a great idea. I would think though that like wing offset you'd want the inside side longer.

I was thinking about making a new fuse and boom glued at an angle like you said. I'm currently using 1/4x1/8 for my fuse and 1/8x1/8 for my boom. Would that offer enough surface area for a strong joint?

[YadoMestor]

I have a new query:

I am considering moving my fin forward on the fuselage, so it sits directly in front of the stab.
Would this introduce any problems?

[jander14indoor]

Assuming you have a fairly long plane, shouldn't be a problem. Pretty common solution on really light planes.

Jeff Anderson
Livonia, MI

[YadoMestor]

Thanks!
I also have one additional question, but I'm not too sure if it fits in this topic:
Whenever I create wash-in, the leading edge forms a very shallow V, instead of one side being horizontal and the other being titled up.

[NJman-77]

how long should [one] the moter stick be? after that how long for the tail boom



ive heard the longer the better.

[jander14indoor]

Motor stick should be long enough to prevent knots from bunching as the motor unwinds. Ten to twelve inches is good, shorter is better because it can be lighter and stiffer.

The tail boom, on the other hand, depends on other aspects of the design. Large wing/large tail desings fly best with a long distance between wing and tail. Small tails should be a little closer in. That said, the usual range that works well is sixteen to twenty inches seperation. Shorter for smaller tails, longer for big ones.

Jeff Anderson
Livonia, MI

[NJman-77]

thanks

[Taran]

I just read a book about flight and it said that a good geometric angle of attack is around 13 degrees, but seeing all the planes people have built, they are nowhere near 13 degrees. May be only for heavy aircraft?

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