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

D.D. or Whiplash flutter ?

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Old 08-27-2002, 11:31 AM
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cappy68
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Default D.D. or Whiplash flutter ?

I'm leaning towards buying a D.D. and putting a Jetfire .50 on it.
Someone told me that this combo can run into flutter problems at
high speed, however I havn't seen anyone mention this on the forum? Has anyone experienced flutter problems with this combo?
Thanks
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Old 08-27-2002, 03:45 PM
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Cactus.
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Default D.D. or Whiplash flutter ?

for Dusts cut the center ribs out for servos, point the horns outwards to have the control horns as far out as possible with straight control rod runs. this also hides the servos out of the airflow at the same time. ( dont link the control rod to the bottom servo arm, and horn on the elevon upper surface, it leads to bad flutter, even on 30mph funflys, ask me how i know )
after that as long as you seal the hinges on DD, any flutter you get on either plane is your fault for not using strong enough servos or control rods
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Old 08-27-2002, 04:08 PM
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Default DD flutter

Cappy,

As long as you use strong enough servos, heavy-duty hardware and 4-40 rods you shouldn't have any problems. Remember the airplane is covered with UltraCoat in one continuous piece on top and bottom. You tuck the UltraCoat into the hinge line with a trim iron.

The only time I had flutter was when I used cheap servos. I started out using FMA high torque coreless servos. After about fifty flights or so with the Jett FIRE 50 I got flutter. Turned out the bearings and gears were shot. I could wiggle the servo arms back and forth 1/8" even with power on. After switching to JR 8101's the flutter went away. They are high torque, coreless, nylon geared servos with wide-spaced bearings.

You can probably get a way with cheap servos for a while but over time I think they will get sloppy on you. Best bet is to go with the best servos you can afford right off. If I was doing another Diamond Dust I would go with 9411 mid-sized digitals.
So far the 8101's have worked out well and are a bit easier on the wallet at 69-75 bucks apiece.

Good luck with your Dust. When it comes to max wow and fun factor in RC you can't do any better than a Diamond Dust or Whiplash.
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Old 08-27-2002, 04:23 PM
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Default D.D. or Whiplash flutter ?

i'd heard about the covering comming off so i covered it in each pannel. good thing too, the bottom film came loose by the engine mounting and tore off, leaving me with the bottom tips and compleate top. was out of trim, slow pass to check for condition, and carried on flying, was the first flight of the day, wasnt going home that easy. bottom now covered in Solartex to stop punctures and every seam and LE covered in tape
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Old 08-30-2002, 07:50 PM
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Default D.D. or Whiplash flutter ?

Yeah,
wingtip turbulence, control linkage/servo slop, hinge gaps, heavy ailerons material, leading edge thickness on the aileron less than that of the wings trailing edge, and speed, all contribute to flutter.
I believe that any plane will have flutter problems if it reaches enough speed. The trick is to keep the planes flutter speed greater than its maximum flying speed.
But WOW! That sound sure does get everyones attention at the field.
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Old 08-30-2002, 07:56 PM
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Default D.D. or Whiplash flutter ?

umm reading that and im thinking, that causes it too? lol

theres a Correx SPAD here that always flutters, but nothing will happen to it, its getting very funny now the pilot does all he can to get it there.
got it the other day on my baby Shrike when i tried a newer bigger engine, think it was ailerons cos the torque rods are long and a bit sloppy, but it kept going
i've had flutter on my dust, but it wasnt elevons, it was the covering. real rough windy day ( big turblence comming over the cliffs ) and i went though a wind shear. what a rumble, like a sonic boom
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Old 08-31-2002, 12:17 AM
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Default Flutter

We have pilots regularly flying the Whiplash at speeds exceeding 200+ MPH with multiple flights and no flutter. Of course the setup and rigid design of the Whiplash does everything to try to minimize flutter from happening. In addition, there is no covering to flutter, buzz or come off. Just ask anyone who owns a Whiplash.
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Old 09-03-2002, 08:17 PM
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Default D.D. or Whiplash flutter ?

Read the "Whiplash 2 down RIP" thread, Mar. 2002.
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Old 09-04-2002, 12:55 AM
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Default D.D. or Whiplash flutter ?

Like I said I still highly recommend a whiplash. On my first one I have a os ducted fan 46vx. Whats funny is that my friend has the same engine on his whiplash and you need to see the props he has gone thru trying to keep up with me. Not breaking them but trying to find the right one. I still don't know how the size got scratched of my prop.
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