Q: Mounting engine on flying wing

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A power source mounted ABOVE the wing will give a "nose down" force so some degree of up thrust is desirable - in some cases essential. I've never tried to do this with a flying wing so don't know how much would be required.

Cooling is also usually desirable, but again I don't have much experience with electric motors.

If the motor can be mounted in line with the wing, then up or down thrust shouldn't be needed, but some side thrust to counteract torque might be.

HTH

Malcolm

On Thu, 13 Oct 2005 19:12:56 GMT, Kevin Bailey wrote in :

Hokey things often work with cheap, light planes.

Since you're working in coroplast, you have nothing to lose by trying several experiments to see what works.

I can't answer that in the abstract. It seems to me that the flying wings I've seen have a thrust line centered on the chord of the wing. It's a reasonable thing for you to try. If the wing climbs uncontrollably under power, turn the power off, glide back down, and try again with more downthrust.

(By downthrust I mean that the engine at the back of the wing points downward. That should lift the trailing edge and force the wing to point more directly into the relative wind.)

I don't see why your proposal wouldn't work--but I haven't built the kind of airplane you're building.

Let us know how your experiments turn out!

Marty

OK. I'm no expert...but I've built four of Jerbear's Simple Wing, and the mounting described actually works fine. On the JSW, it's even simpler: instead of coroplast, you use half a popsicle stick on the bottom, and two tie-wraps. But you also put a piece of popsicle stick under the aft end of the engine so that the thrust-line of the motor (i.e., the extension of the axle, for direct-drive) passes through a point somewhere between the CG and the forward tip of the wing, and perhaps a little to one side. With zip-ties, it's pretty easy to adjust this after a first test-flight. If the thrust-line meets the wing too far forward, you'll nose down when you apply the throttle. If it meets it too far aft (i.e., you put in three popsicle sticks under the back end), you'll nose up with more throttle. You want neutral response. If you get your test-glide to look good, and then just goose it for a tenth of a second, the effect will be obvious.

--John

Speaking of the JSW, if you've got some spare parts lying around, and if you're good enough to build a fancier model, you can build a JSW in about 2 hours, start to finish. If you don't have a spare small rec. and a couple of servos, it'll be expensive. If you've got some that you don't mind using for a few hours, slap 'em in a JSW. It's easy enough to fly that I, with just a few hours of FMS training and a few minutes of helping my son with an "Outlaw", managed to fly it OK (alhtough it's good to have some packing=tape at the field to tape the servos back in place after that first nose-in landing).

Why do I mention all this? Because if you've spent time and effort on your OTHER wing, you might want to whip up a JSW to practice with at low cost. Aside from electronics, it's about a $2 model. :-)

For more info:

-John