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Old Jan 28, 2013, 04:24 PM
colorex is offline
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Tek Sumo / MS Swift / Popwing Crashproofing?

Ok, so I just got a Tek Sumo for a friend of mine and I need to rig it up well as he is a beginner. Now I've seen tens of pictures of crashed flying wings, of course while easy to fix they all break in the same spot, namely from the nose towards the motor mount, sometimes breaking or ripping out the carbon fiber spars.

So I was thinking maybe there could be a better idea? I know that many people tape their wings, but my tape just won't stick to the EPP.

I came up with this idea. I have a Bixler/SkySurfer myself, and I use the velcro strip method to fasten the wings. When I hit hard, the velcro just undoes itself and no damage is done to the wings. So I thought maybe this can be used for flying wings too?

I would expect this to work, but I want to ask the guys with experience if it's worth trying or if I should do like everyone else and break and fix it.

So this works like this in my head. There are short curved spars inserted in one half of the wing, glued in the other. The nose is put together with a pivot of some sort, maybe thick thread. There is velcro across the wing halves, absorbing the impact. Maybe add or replace the velcro with a wide rubber band (as found in clothing) to absorb shock on nose-ins.

The TekSumo will run a FloaterJet replacement motor, with a 1300mAh 3S.



If this has been asked, if there is a thread with mods for this kind of wings, please post links to threads as I have not had luck with the search function.
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Old Jan 28, 2013, 06:14 PM
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I like the way you think colorex. I fly on rocky slopes and things break.

The pivot would have to be a very strong to keep the wings aligned because there are also twisting and pitching forces on impact. Without alignment, the curved spars would tear their foam holes.

Have you seen how http://crashtesthobby.com uses a string on the trailing edge?

I had another idea: hold the left and right spars together on top and bottom with clips (google: "slot car" track clips). The clips break or release on impact. I have not tried this: get some old slot car tracks, cut out the clip retaining part, and glue the clip retainer onto the center of some spars.
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Old Jan 28, 2013, 07:20 PM
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Quote:
Originally Posted by wolfv View Post
I like the way you think colorex. I fly on rocky slopes and things break.
Thanks for replying.

Quote:
Originally Posted by wolfv View Post
The pivot would have to be a very strong to keep the wings aligned because there are also twisting and pitching forces on impact. Without alignment, the curved spars would tear their foam holes.
If I make this it would not be a normal 1 axis hinge, rather a leather strip glued to the leading edge of both pieces. So you can bend it and twist it in any direction.

Quote:
Originally Posted by wolfv View Post
Have you seen how http://crashtesthobby.com uses a string on the trailing edge?
Haven't seen it, did think of it, but the way I see it it would interfere with the elevons. Might be a way though. I'll have a look at the wing again.

Quote:
Originally Posted by wolfv View Post
I had another idea: hold the left and right spars together on top and bottom with clips (google: "slot car" track clips). The clips break or release on impact. I have not tried this: get some old slot car tracks, cut out the clip retaining part, and glue the clip retainer onto the center of some spars.
Sounds like it could work, except for the rigidity of the junction. You wouldn't want the wing to come apart in a high-G manuever. I was thinking like 3 pieces of 2 inches of barbecue skewer into the wing itself, acting as a short spar.
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Old Jan 28, 2013, 09:03 PM
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pivot
Quote:
Originally Posted by colorex View Post
a leather strip glued to the leading edge of both pieces. So you can bend it and twist it in any direction.
But then the spars would tear out of the foam.

Crash Test hobby string
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Originally Posted by colorex View Post
it would interfere with the elevons.
The string is not actually in the trailing edge, its in front of the elevons.

Another ultra durable flying wing is Windrider Bee2. Use thinned goop glue to stick the fiber tape to EPP. You can see the tape pattern on the EPP here:
http://www.rcgroups.com/forums/showt...81#post9908046
http://www.windrider.com.hk/product.asp?id=165
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Old Jan 28, 2013, 09:37 PM
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Thanks, I'll check it out. I asked over at the flitetest forum, didn't get so many responses that incited me to try, so maybe I'll just glue it and wreck it like everyone else.

http://forum.flitetest.com/showthrea...ll=1#post41372
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Old Jan 28, 2013, 09:49 PM
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you could "shock cord" the parameter like the Assassin wing as well as packing tape the nose.
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Old Jan 28, 2013, 11:43 PM
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Whirlcap, I think you mean perimeter.
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Old Jan 29, 2013, 01:38 AM
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Quote:
Originally Posted by colorex View Post
Ok, so I just got a Tek Sumo for a friend of mine and I need to rig it up well as he is a beginner.
If your friend is a total nub, he should start with a simulator. Reset on a sim is so much faster than hot gluing a foamy. Typical learning sequence might be:
  1. learn to fly on a simulator
  2. destroy the first airplane and learn how fix it
  3. buy a second airplane that is super durable like the "Assassin" or super ease to fly like the "AXN Clouds Fly Floater Jet"
    http://crashtesthobby.com/products/assassin
    http://www.youtube.com/watch?NR=1&v=...ture=endscreen
Tek Sumo is actually a good first airplane because with some simulator time, the Tek Sumo is easy enough to fly, and it is easy to fix.
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Old Jan 30, 2013, 12:17 AM
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I snapped the nose off of mine. It break because the foam is thin where the battery cut out is located. Since it needs nose weight anyway, I was thinking about fiberglassing the nose area with 4oz cloth and clear Resin Reserach surfboard epoxy. Get forces back to the thicker foam.
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Old Jan 30, 2013, 09:21 AM
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Quote:
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Whirlcap, I think you mean perimeter.
I did . Spelling was never my strong point and this iPad corrects me in ways I don't intend it to.
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Old Jan 08, 2015, 01:15 PM
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Shoe Goo tricks...

Quote:
Originally Posted by rhodesengr View Post
I snapped the nose off of mine. It break because the foam is thin where the battery cut out is located. Since it needs nose weight anyway, I was thinking about fiberglassing the nose area with 4oz cloth and clear Resin Reserach surfboard epoxy. Get forces back to the thicker foam.
If you build up the center section glue joint with Shoe-Goo (not Amazing Goop it breaks much easier) joining the wing halves so you have a thicker center seam and horizontally cut the nose with a jewelers saw blade and re-glue it building up a seam the thickness of the blade used doing one side at a time (I use wax paper after it set's up and is not sticky so I can keep it flat and hold the original shape as the Shoe Goo shrinks, takes a couple of coats) you can make the nose really strong with one final outer coat of Toluene solvent thinned Shoe Goo, no need to add weight trying other methods. The nose ends up durable like a shoe, adds little weight, and done right you can hardly see the seam. I then extend the cut an inch or more past the horizontal cut down the leading edge to stress relief where the glued area stops. I then use a new sharp X-acto blade and cut down the exact center of the leading edge a half inch deep and then re-glue it adding a center seam down the leading edge that's almost impossible to see done right but adds a lot of compression strength and for combat I'd add some Kevlar kite line that adds almost no weight but makes the leading edge and nose bullet proof but flexible. And don't use hard CA or hot glue anywhere the wings needs to flex absorbing energy. I use Shoe Goo to put in carbon spars as well. CA just creates a brittle wing. Better to have it bounce well;-)
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Last edited by John Hendry; Jan 08, 2015 at 01:24 PM.
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