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

Whiplash

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Old 12-13-2002, 03:22 PM
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jetsett
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Default Whiplash

I just finished my whiplash.
I was wondering, ?......I am using Jr 8411 DS digital servos but they keep on buzzing. Is this normal. The elevons seem to deflect upwards about 4 degress without the servos hooked up. When I attach the servos, they start buzzing? What's a good way to fix this problem. any help would be greatly appreciated.
Also I am using a OS .46fx all the way back on the motor mount, 750 mah battery at the back of the battery compartment and heavy duty steel pushrods at the rear and I am still nose heavy . CG is about 2" behind the front of the compartment. I guess I must have a heavy Os engine
LOL
Please help


Thanks all
Don
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Old 12-13-2002, 03:32 PM
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Synthetic
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Default Whiplash

Don, buzzing is not a problem. That is just the servo centering itself many many times per second....
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Old 12-13-2002, 05:31 PM
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Lee Cox
 
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Default Whiplash C.G

Acetumper1...

This seems strange to have the C.G so far back.
Until I put the Jett 50 in Spider I was using the same set up as you.
The engine balanced about 50% up the mounts, just so the front of the engine was flush with the front of the mounts.
battery was at front of compartment and rec back.

Found the C.G to be perfect at 2 1/2" back from front of battery compartment, in line with the bottom of his eyes!!

I now have J.R 8411 and they also hum tunefully!!
Watch the throw rate, use expo and have high rate at about 5/16 up and down. low rate at 3/16 up and down.
use a 10 x 6 for the first few flights until you are happy and it's well trimmed then try anything around 9 x6 or 8 x 9...

Good Luck
Lee
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Old 12-13-2002, 05:37 PM
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Lee Cox
 
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Default Whiplash

and another
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Old 12-13-2002, 06:22 PM
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George
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Default CG?

Don, I'm running the same exact set-up (OS 46 fx) except Hitec digitals, but my batt. is in the front and Rx in the back and engine more towards the front. Mine balances at about 2 1/4" back and does fine.

I would re-check everything, something seems wrong. Oh BTW, I do have the pre-painted version. (Spidey)

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Old 12-17-2002, 04:15 AM
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Default Whiplash CG

Don,

Seems kinda strange that it's still nose heavy. Did you mount the motor as far back in the horseshoe as possible? Also, how did you check the CG.? You need to use some type of straight edge and make 2 marks at the wing LE to check it. If you were guessing about where the 2.5" mark is under the skid plate, it's really hard to get it right there. One of our guys in the shop is using the same exact setup, but with a Performance Plus tuned muffler on his and the balance is fine. Check everything again and be sure. Happy Flying...
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Old 12-17-2002, 02:20 PM
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Default Buzzing

It's not the deflection of the surface back to neutral that is making the servos buzz. They always do that, it is a perfectly normal characteristic of digital servos.
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