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

DD trailing edge

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Old 05-19-2006, 01:19 PM
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flyingmachine
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Default DD trailing edge

Just wondering guys, why is the trailing edge so sharp on the DD? Does it need to be like this? I have always had sucess just rounding square wood off.


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Old 05-19-2006, 02:38 PM
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Default RE: DD trailing edge

flyingmachine:

You are into part of the speed learning curve. The sharp trailing edge reduces drag. The sharper the leading edge, the more drag is reduced. However, when you create a sharp leading edge, you also create some additional problems such as a high speed during landing, something most of us try to avoid. There are compromise in the design of airfoils and related airframes. If there is another dust or similar wing in your club, watch how the thing flys and how its launched. They are fairly hot landing ships, so some care is needed. One of the guys in our club refuses to hand launch these things, he uses a pvc pipe launcher, a simple 3/4" pipe each side of the wing set on a 45% angle on the ground and a foot push release. Have seen several on line in the past. I have a scar on the top of my head from hand launching a wild one's first out of trim flight. Care is in order here. ENJOY Rever bro 119
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Old 05-19-2006, 03:26 PM
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Default RE: DD trailing edge

understood, so I should sharpen the elevons to match?


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Old 05-19-2006, 04:42 PM
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Default RE: DD trailing edge

The trailing edge of the wing is sharp so the elevons don't bind. If you just round them off you will get binding if the hinge line is close and you use a lot of flight control travel. The DD needs a lot of travel for landings since there is no landing gear and you want to land as slow as possible. Mine only slides a foot or two when I do a good landing, you can slow this plane down to a fast walk if you need to.
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Old 05-19-2006, 05:23 PM
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Default RE: DD trailing edge

Hi Huey-Pilot , I believe you run a 60LX on your DD..that would have to be a leathal combo,I was going to put one on a whiplash, but on the light dust that things got to be an animal ... any chance of a video or at least a photo??
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Old 05-19-2006, 06:01 PM
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Default RE: DD trailing edge

ok thanks, I put only a slight curve in the elevons nothing harsh, I also tapered the rear of them also and rounded them off slightly, not so much that trim is touchy.


THANKS

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Old 05-20-2006, 03:38 PM
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Default RE: DD trailing edge

For a photo of my DD with the Jett 60LX go to http://www.jettengineering.com and check out the Jett photos hall of fame, it is the DD with the red tails and black top covering. There are also several real nice DD's at this site. I will try to post a photo after I figure out how to do it.
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Old 05-20-2006, 04:03 PM
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huey - pilot..I checked that out ,i have seen that there when I visited last week...very nice..I'm in great envy over that engine!!!..but seriously.. thats got to be a blast to fly!!!
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Old 05-20-2006, 09:02 PM
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Default RE: DD trailing edge

The plane flys great but the engine is rough on the servos, 8 flights and 2 HS 81's out of commission. The last flight the whole tank of fuel was at full throttle until the tank ran dry because the throttle servo failed at full throttle. I have installed a Hitec 225 servo for the throttle but I haven't flown the plane since installation.
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