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        Discussion help redesigning my wing tips on my Grim Reaper

#1 MaydayMayday Jan 17, 2013 09:22 PM

help redesigning my wing tips on my Grim Reaper
 
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I have a 55" Grim Reaper I got from a local club member who didn't really like flying. Well he didn't like launching to be exact.

So the wing tip are a little worn and not the correct size. So I was going to make them larger.... BUT I realized the elevons do not correctly follow the edge of the wing (where the winglets would extend)


So question one, I'm assuming that the control surface needs to follow the edge for the fins to be effective over the control surface. (this statement will make more sense if you read it and look at the picture),

Question two, if the corner needs to be added for I just glue foam on there, I mean that seems like a lot of leveraged weight to ad, I'd like to keep this plane aerobatic (still refuse to use the word "3d")


Lastly, to the shape and size of the winglets. I'm wanting to do them top and bottom and run the entire length of the edge of the wing including the control surface. What little research I've done this seems to be a good idea, but here is where the conflicts seem to start.

- How tall both above and below do they need to be? Between the added weight and additional surface area it seems like it might affect performance, is this just an assumed trade off where I have to decide?



The plane flys pretty well at higher speeds but still wiggles a little and at low speeds wiggles a lot even in no wind and in a banking turn tends to yaw. I do have the CG well balanced.

#2 ashdec87 Jan 17, 2013 09:47 PM

Maybe the older reapers were different, but mine has the elevons stay inline with the wingtip. Also, I extended my wing tip to the trailing edge of the elevon. This all but eliminated yawing, even in the worst of winds. I fly mine FPV so any yaw is pretty noticeable

#3 MaydayMayday Jan 17, 2013 11:51 PM

That's what I'm after is the stability. Why it was setup this way I don't know, probably by mistake. Hence the desire to change.


Quote:

Originally Posted by ashdec87 (Post 23848515)
Maybe the older reapers were different, but mine has the elevons stay inline with the wingtip. Also, I extended my wing tip to the trailing edge of the elevon. This all but eliminated yawing, even in the worst of winds. I fly mine FPV so any yaw is pretty noticeable


#4 Jon Snow Jan 18, 2013 12:22 AM

Extend the surface,cocktail stick through to reinforce.Before you add bigger winglets:more weight try moving these back,see how it flys.They are more effective over the rear 2/3 or so.
Stuart

#5 MaydayMayday Jan 18, 2013 12:42 AM

ahhh, ok! I will have to try that.


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