Talus: High Aspect, Constant Chord Swept Wing Revolution - Page 22 - RC Groups
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Apr 20, 2007, 03:45 PM
PWP!
ajroahkni's Avatar
Glad you guys got the shirts.

I've been working on an EPP pod to replace the laminated ply pod. Why? Bigger holding area for gear, a little more bounceable (less broken nylon bolts), lighter (gave it a little more nose for the cg), and I gots epp scraps. I'm hoping that this will reduce ~2 oz from my talus (back to 27.2 oz?).
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Apr 20, 2007, 03:49 PM
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EdSoars's Avatar
Carl: I don't understand about the span weighting reducing flutter. One method that has been used in full-size planes is to add a little weight to the LE at the tips, kind of a counterbalance. On the Talus, it would have to be a half to one ounce on a stick out in front of the LE...not good in landings.

I'll have to try the PU and FG screen or roofing tape, weighted in the beds. It's just so darn dry here that PU acts very differently from one application to another.

Hangtight: the G10 is .010 thick. Any thinner would definitely be too weak; it isn't as tearproof as I'd hoped, but it sure is stiff. It's also fairly heavy. May be that the best application for it is as a local reinforcement and stiffener. Anyway, I'll give it a shot over a set of EPEn cores and see how it does.

ed
Apr 20, 2007, 04:02 PM
Registered User
EdSoars's Avatar
John A: I didn't get MY shirt yet, but then I'm farther uphill.
I've been working on getting stuff OUT of the pod and into the keel. My 4-servo just barely achieved that when I removed the pin switch, replacing it with a micro deans plug that now sits on top of the wing. The keel now is purely a nose weight holder.

ed
Apr 20, 2007, 10:17 PM
Fly The Lift You're In
After I got home last night I got looking at my Talus and realized that it needed a bit of maintenance. My endless learning curve, combined with our local landing area options, had taken its toll, particularly along the LE and tips. I peeled quite a bit of mylar and tape from various areas, removed the tips, and pulled layers of tape of the tip area.

I gooped the LE in several places, especially along several inches from the tips inboard. When I build my next Talus, assuming it is made of foam rather than some exotic material that is used in the manufacture of elephant feeding troughs or something, I will definitely goop the whole LE. The tips in particular, being the preferred landing gear of the Talus, take quite a beating. I applied new mylar where needed, and reattached the tips. I tried to clean up all the little tears and dents as much as possible.

I also added a set of elevon seals made from a strip of tape, half of which is coated with cornstarch to kill the adhesive. All in all, she looks pretty good again. I also reduced my pitch throws a bit, and increased the expo a touch.

Today it was blowing 20 to 25 straight into the DOW hill west of town. On top it was actually 20 to 30 with gusts to near 40. I measured one at 37.8. I flew for about 1/2 hour. Again, noticeable improvements in handling. That thing was cranking and slicing! The reduced drag was huge. I only had two knee shaking experiences. One when I lost control of an inverted high speed pass and almost ate a cliff face, and another when I misjudged my landing approach and dropped it off the west side of the hill into a talus slope. More repairs tonight. I wonder when I will stop finding way to make this plane feel even better?

rm
Apr 21, 2007, 11:24 AM
Registered User
EdSoars's Avatar
John A: got the shirt, and can't wait to show it off! Many thanks!

John C: glad the Talus is still improving for you.

I got G-10 skins glued onto a test EPE core: used 3M-77 on one side, 3M-90 on the other. 3M-77 held fine so far, and is much less messy to deal with. With the heavy foam and skins, and more G-10 reinforcing the root ends, the panel weighs 9 oz. It's stiff as a brick. Promising for lead-sled days! Add 6 oz for radio and 4 MG servos, 5 oz for keel, joiners and balance weight, and you're up to 29 oz. Looks like a full-rigged test is justified.

I also polycrylic varnished the bottom CF+ripstop nylon skins onto the blue foam core set. There are a few un-secured bubbles, so a light coat of 3M-77 would be in order before varnishing. Seems to make a fairly decent straight TE, too. I think this has more promise, as the amount of CF can be varied to suit the purpose and wing loading.

More next week.

ed
Apr 21, 2007, 03:02 PM
PWP!
ajroahkni's Avatar
My talus is at 28.1 oz with the new epp pod. Ready for seacliffs!

Apr 21, 2007, 04:47 PM
Fly The Lift You're In
That thing should rock. Mine at 26.8 oz., and not nearly as clean, was handeling the 37+ mph winds yesterday just fine.

RM
Jun 04, 2007, 12:32 AM
Registered User
EdSoars's Avatar
It's high time for an update on Talus development. I've finally gotten a build that works...so far.

This version has a wing chord enlarged at the root to 7" and reduced at the tip to 6". It was 6.5" root to tip. The change makes it easier to fit all the radio gear into the wing roots. Nothing is in the fuselage, which is now a solid plywood keel with only the balance weight in a cutout up front. Much more damage resistant.

The wing looked like it wanted to be higher aspect ratio, so the span is stretched from 60 to 68".

The airfoils are true Martin Heppler, MH 44 at the root and MH 43 at the tip. No modifications for flat balsa surfaces.

From the leading edge back to 25% is 4# EPE. Then there's a full-depth CF sheet spar. The aft 75% of the wing is 2# blue foam. Takes some time to cut a core, but it makes for rigid, true-airfoil control surfaces, and a ding-resistant LE.

Covering: cut out servo holes and wire channels, smear PU glue over bottom surface, spritz with water, drop on the screen door FG, let it set up overnight. Sand off the glue high spots. Thin a couple of tablespoons of lightweight spackle and brush into the screen.

Install servos, add screen to top surface. Apply spackle as above.

Repeat spackle if desired. The smoother the better. Filled screen mesh is much stiffer than unfilled.

Add FG reinforcing at wing roots.

Cut out holes for batteries and radio. Install gear.

Covering...iron on film, fabric, or glue on some ripstop nylon. I haven't perfected the application of ripstop, but it's the best covering i've seen yet for low stretch.

More soon I hope.

ed
Jun 04, 2007, 07:04 AM
The Glider Version
flatstick's Avatar
Would you mind describing the spar Please.
- how thick.?
- how is it adhered to the EPE and Blue foam?
...........this sounds like a really stiff design if the carbon cant twist.
Have you been able to mock up and weigh this design?
Glenn.


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