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techwing gets winglets and slots

Posted by crystal garris on July 18, 2014 at 9:49pm

Hey everyone,

I wanted to post an update on the work I have been doing on the techwing design.

The new design is scaled up some to a 40 inch WS. It also includes real Grantz type winglets, a longer tip cord and fixed LE slots.

Flat plate:

With winglets:

By reducing the vortex, you can expect less drag, greater lift, and better stall characteristics.

The next thing I did was add fixed LE slots to the outboard panel. LE slots allow the wing to fly at much higher angle of attack .

This is the techwing at a 13 degree AoA. Dark blue is the most negative pressures.

Here you can see the slotted airfoil at a 13 deg AoA. It achieves a 1.19 CL normally this airfoil would have a Cl max of ~0.75.

The slots also help to increase aileron effectiveness. I just finished the first mold for the prototype. this is the bottom of the fuselage.

fixedwing, techwing, uav

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Comments

Eli Cohen July 19, 2014 at 4:38pm

What's the drag penalty for the slots at low alpha? Seems like you would cruising at <7 deg so you might be paying an endurance penalty for the better near-stall behavior. Also, what about robustness in the case of catching an LE on something? Seems like you could lose the whole front structure.
Moderator

Dwgsparky July 19, 2014 at 3:11pm

Hi Wayne, the X5 size is ok for very light cameras but it's a trade off between payload and batteries. As a comparison the X6 is MUCH more stable and can fly slower than the X5 but the removable wing panels make shipping easier and cheaper. I would look for a 52-54 wing as ideal with removable wings, love your design.
Juan Carlos Hdez July 19, 2014 at 3:09pm

+1 also
Eric July 19, 2014 at 1:43pm

+1 for interest in the mold making process. Would love to see how that's done.
100KM

crystal garris July 19, 2014 at 11:14am

Rhino for CAD and openFoam for CFD.
100KM

crystal garris July 19, 2014 at 9:24am

Yes, I was planning on some how to basic videos of the mold making process.
100KM

crystal garris July 19, 2014 at 9:23am

@Chris,

The payload area will be as generous as possible. As for total payload weight, that will mostly depend on the size I end up with. A 80 inch WS model probably would compare to the techpods 4lbs+ payload.

The main objective of the techwing is flyability, compact design, simple mechanics and crash-ability.
Moderator

Chris Norris July 19, 2014 at 9:11am

Hi Wayne, this looks great, how's it going to compare to the techpod in terms of payload etc?

Also on a separate note. How do you go about making molds for and forming the fuselage? I'd love to see an article on how it's all done.
100KM

crystal garris July 19, 2014 at 8:58am

Thanks!

@Antonie

That's been the #1 request so far. I am a little torn as to what size to make it. On one hand I want to make it just big enough to carry a compact camera for photogrammetry, on the other most hobbyist are interested in a 60"+ WS model. I am exploring the options. Maybe two different models, maybe expandable wings.
Antonie Kruger July 19, 2014 at 7:36am

Hi Wayne, looks great. You should make it a 80 inch from the start - you know the requests are coming. This wing will be about the size of a X5.