Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

Diamond Dust elevons

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Old 12-31-2002, 09:58 PM
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N2UMK
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Default Diamond Dust elevons

Happy New Year!!
The elevons are trailing edge stock. How do you recommend you finish the leading edge of the elevon for attachment to the triangle stock trailing edge? Bevel the edges @45 degrees on the center line of the leading edge? The plans show the CA type hinges, however the LE of the elevon is the short side (edge) of the right triangle. Any pictures or tips would be appreciated. Mine is almost ready to cover..
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Old 12-31-2002, 11:21 PM
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ChuckAuger
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Default Elevons..

I didn't go per plan..I left the TE of the wing square and put the tri-stock on the elevon. It just looked funny the other way to me. I know many had been built without the benefit of my kit bashing, but I just went with what I was used to.

Also....and this is just speculation, I don't want to get into an aerodynamics lecture...my elevons were thinner than the TE of the wing, so I replaced them with some 5/16" thick TE stock. I did this after reading about Dave McDonalds flutter problems with his DDust until he went with thicker elevons. I don't know if it was needed, I think I remember the kit mfg. going to thicker stock in later kits. But mine never fluttered and I flew it WFO all the time, full power dives and all.

I had 5 CA hinges on each elevon, with one directly under the control horn..the horn screws went thru the CA hinge...to keep it from deflecting under load. Don't know if it was needed, but it never fluttered.

This is just how I did it...I'm not trying to sway your decision as to how you do yours.
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Old 01-01-2003, 12:57 AM
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Default Diamond Dust elevons

I remember reading about the flutter problems also. The newer kits supposed to have the thicker elevons with them.

As for attaching them I left mine flat also and just attached to the triangle stock. I still have maximum travel on each. I also covered my wing to elevon with one continuous piece of covering and over the CA hinges. This also is supposed to keep the flutter down.

I also thought about cutting 45 onto the elevons but didn't think it would really make a difference. Now as for travel yes it would but then they would be standing straight up if the 2 angles was maxed out. As for trying to cut down on drag i focused more on my fuel tank and servo exposure. I figured this is where the most drag could be shaved off. I am sure there are other things but this is the way I did mine.

One more thing if you want 45's on the elevons you could also attach some triangle stock on the flat part as well.
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Old 01-01-2003, 03:08 AM
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Default Diamond Dust elevons

Thanks for the insight. Thinking about it more I might bevel the LE of the elevon starting at the top of the LE and cut back at the standard 45 degrees toward the bottom of the LE. Without that taper the elevon canot move downward. This will give me plenty of down (won't be used much!) When covering with one piece of covering the elevons are folded back over the top of the wing when the bottom covering is applied. Then held deflectd down when the top covering is applied. This is the typical installation for a "monokote" hinge. It seems that the CA hinges would have to go in at the top of the elevon (bent at 45 degrees at the center of the hinge) and the top of the trailing edge - also with the CA hinge bent down as it enters the TE of the wing.
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Old 01-01-2003, 03:43 AM
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ChuckAuger
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Default Hinges..

I can't picture the hinge situation you mention...with the tri stock on the TE of the wing or the LE of the elevon, the CA hinge will be slotted directly into the center of both the TE/LE of each surface..

Slot on the center line of each surface....
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Old 01-01-2003, 06:15 AM
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FlooredCOBRA
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Default Diamond Dust elevons

Yeah I don't quite understand what you mean on your hinges either. I posted a diagram on how mine was done. The CA hinge is marked in blue.
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Old 01-01-2003, 02:41 PM
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Default Diamond Dust elevons

Attached is a picture of what I tried to describe. Thanks for the picture flooredCOBRA. I knew that's what they were saying but it doesn't look right to me. Using one piece of covering provides a smooth transition over the elevon top. Without the covering it looks like it would cause a lot of drag.
ChuckAuger - you said the same thing that flooredCOBRA said - thanks to you both for the info. Instead of putting the tri stock on the TE of wing I could (as you both mentioned) glue it to the LE of elevon. Same overall effect and it's how most "conventional" control surfaces are shaped prior to attachment to the wing, stabalizer or vertical fin.
Happy New Year! and thanks - I think I got it now.
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Old 01-01-2003, 05:54 PM
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Default Diamond Dust elevons

I think the reason they have it done this way is because without the triangle stock there would only be a 1/4 square block on TE of the entire wing. The triangle provides for a more sturdy airframe.

Thats the only reason I could think why they did it this way. But yes your right usually it is the other way around with flat on TE and tri or or round LE of aileron. At least was on the planes I built before.
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