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-   -   maybe NOT engine vibration, but FLUTTER (https://www.rcuniverse.com/forum/beginners-85/627899-maybe-not-engine-vibration-but-flutter.html)

paul_c 03-16-2003 05:09 PM

maybe NOT engine vibration, but FLUTTER
 
OK, remember how I told you that the plane was shaking as the engine ran, while the plane was on the ground (tied down)? It sounded as if the whole plane was vibrating, and you could see the horizontal stab shaking pretty good.
Maybe the vibration wasn't from the engine, but from flutter.

Can you see flutter when a plane is tied down to the ground?

Remember, pretty much the whole plane shakes. There is really no play in the control surfaces, except maybe some in the ailerons, but I'm not sure if this is a normal amount. If you take an aileron in your hand, and move it up or down, my servo arm turns immediately . But if I wiggle the aileron up and down gently, there is some play.

ps the plane could be heard to be making the same sounds up in the air today.

pps--Flight #4 today--good landing, no prop srikes! :-)

DaveB 03-16-2003 10:35 PM

maybe NOT engine vibration, but FLUTTER
 
I would be surprised if you are experiencing flutter. I would first check the balance of the propeller and secondly, make sure the engine is fastened in a level fashion, i.e. all four points are contacting the engine mount before tightening the engine mounting fasteners.

DaveB

scalebldr 03-16-2003 10:47 PM

flutter
 
flutter happens when a plane is in flight not sitting tied to the ground.if it is shaking with the engine running find the cause before flying.prop and spinner could be out of ballance or the prop itself is not square at the hub,loose engine mount or engine monting screws.broken mount or bulkhead,bent crankshaft.has this engine been run in a test stand to see if it vibrates there?

paul_c 03-17-2003 12:38 AM

Re: flutter
 

Originally posted by scalebldr
flutter happens when a plane is in flight not sitting tied to the ground.if it is shaking with the engine running find the cause before flying.prop and spinner could be out of ballance or the prop itself is not square at the hub,loose engine mount or engine monting screws.broken mount or bulkhead,bent crankshaft.has this engine been run in a test stand to see if it vibrates there?
DaveB--all seems good re: prop and engine mounting.

Scalebldr--I think you are right, as this developed (I'm 90 % sure) after a couple of rough landings. I guess I run it on a test stand next.

Live Wire 03-17-2003 03:16 AM

maybe NOT engine vibration, but FLUTTER
 
Check your servo mounting . Mine came loose and every thing shook , It was just one rail that came loose and you could even hear it.

TerrellFlyer 03-17-2003 03:00 PM

maybe NOT engine vibration, but FLUTTER
 
Flutter happens in flight,unless you have super large fan blowing on control surfaces,something is out of balance at the engine end,prop,spinner,shaft or loose screws on engine mount or loose firewall,have fun searching.

Unstable 03-17-2003 05:01 PM

maybe NOT engine vibration, but FLUTTER
 
hey paul... how is the condition of your flying field... all of our fields that we use are mud pits....

maybe next weekend (if the weather holds... weather.com is saying partly cloudy for sat and sun.) I can take a ride down there.. I also might be able to convince Marc (RCAdmin) too as he has been trying to find a good field to fly a review plane off of that won't dirty the plane too much (not good for review)

let me know.

paul_c 03-20-2003 02:20 AM

maybe NOT engine vibration, but FLUTTER
 

Originally posted by Unstable
hey paul... how is the condition of your flying field... all of our fields that we use are mud pits....

maybe next weekend (if the weather holds... weather.com is saying partly cloudy for sat and sun.) I can take a ride down there.. I also might be able to convince Marc (RCAdmin) too as he has been trying to find a good field to fly a review plane off of that won't dirty the plane too much (not good for review)

let me know.


Unstable, I'll be out of town this weekend. But I'd love to have you and Marc down here. We have a grass field that is a little bumpy, but not bad. Space is not an issue--the field is across from South Jersey Regional Airport. http://www.njpinebarons.com/
In addition, I have been flying my trainer at a new park here in Voorhees--the park is not yet complete, so there is only light pedestrian traffic. Either which way, maybe we can shoot for the following weekend. Paul

Unstable 03-20-2003 03:11 PM

maybe NOT engine vibration, but FLUTTER
 
cool.. I'll run it past marc.

CafeenMan 03-20-2003 09:27 PM

maybe NOT engine vibration, but FLUTTER
 
One of my planes has waaay too large of an engine on it. Everything is balanced, but there just isn't enough mass in the model to dampen the engine vibration. At idle the plane looks like it's trying to shake itself apart. Once the throttle is advanced a little it calms down. I've put the plane in several terminal velocity power dives and there is no flutter.

My point being that what you're experiencing may be normal, but you should make sure everything is fastened securely and anything attached to the engine crankshaft is balanced.


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