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  #91  
Old 08-24-2012, 07:34 PM
gtmule gtmule is offline
 
Join Date: Oct 2007
Location: Macon, GA
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After reading this thread I was flying today and noticed a really heavy left wing. Started getting paranoid about aileron hinges, etc. Then I realized i had15 in the left tank, 5 in the right, and all 250lb of me was on the left, too. Just a reminder to remember the easy stuff, don't get stressed out, and have fun.
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  #92  
Old 08-27-2012, 06:49 AM
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flyenforfun flyenforfun is offline
 
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Quote:
Originally Posted by DanBaier View Post
I've have lost track of the detail of this thread - but, have you checked the prop tracking?

Dan
Prop tracking is dead on.
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  #93  
Old 08-28-2012, 11:52 PM
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Neal@F14 Neal@F14 is offline
 
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Default Vibrations...

Next time you fly, try yawing the plane back and forth with the rudder and check to see if the vibrations change significantly in tone or strength as you yaw the plane from left to right past the "center". If it does, then that's a tell-tale sign of the back of the canopy skirt vibrating against the turtledeck of the rear fuselage as I'd mentioned earlier in this thread.
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  #94  
Old 08-29-2012, 11:17 AM
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flyenforfun flyenforfun is offline
 
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Well I have some updates.

I may have said this already, but changing the tires cured the shimmy on takeoff and landing 100%. Check that one off.

Narrowed the wing heavy down to aileron symmetry completely. With everything in trail, it flies straight and level with everything still in trail. But when y ou let go of the stick the ailerons deflect a little and it rolls. I took a 2x4 and a mallet per Van's and lightly tapped the trailing edge of the heavy wings aileron. So now it has an opposite heavy wing! At least now I can fine tune and solve the problem.

My biggest problem (I think) is still not solved. Vibration. Dynamic Prop balance didnt fix it. Its not the skirt or the fairings. Exhaust isnt hitting the airframe, baffles arent hitting the cowl (anymore). It seems to be RPM related. I just have no idea.
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Last edited by flyenforfun : 08-31-2012 at 11:11 AM.
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  #95  
Old 09-02-2012, 07:26 PM
thinkn9a thinkn9a is offline
 
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Location: Mississippi
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Default Any more updates?

Is it REALLY RPM related.. or is it SPEED related?

I'm confused that you had it dynamically balanced,... yet you have vibration,... seems to me it would have indicated and issue if you had that done. (vibration not able to be corrected). Does it shake "on the ramp" or only while flying?

So,... is it something else,...a.) wing/fuse -seal/gasket loose? (been known to scare the bejimminies out of folks, when it wiggles out and starts shaking) b.) seal between cowl and inlet ramps not "fair and smooth",.. and shaking with air across it c.) wing walk non-skid pad coming loose and shaking air/wing d.) your other tires were out of round,... how does the tail wheel look,.. any abuse to it causing out of round? (as you found out, .. out of round tires shake) e.) all the access panels on tight? sure? f.) what about the bottom of the cowling... any chance the FAB is rubbing or hitting at some point.... they are known to have some fit-up and tweaking required depending on engine, carb/TB, and cowling arrangement. g.) something not "strain relieved" running to the engine and up against the engine mount or firewall,... causing a "sound short" (and getting ready to fail in the future)

It really is amazing how little it takes to shake the plane.

Read about a Reno racer that spent a LONG time with a experienced crew, before they finally traced a problem down to a cover not sitting fair.

keep plugging and keep us informed,... as you can tell,... you have us stumped,.. and we need some answers..
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  #96  
Old 09-02-2012, 09:12 PM
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donaziza donaziza is offline
 
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I had a bad airframe vibration, primarily when I pulled the power back. ( RV 8) (Lyc O 320) Turned out to be the flywheel. It had " Experimental" only stamped on it. Nobody had ever noticed that before. Borrowed a flywheel from another guy still building his RV 7 and swapped. Vibration gone. Gave him his flywheel back, and bought a new one of my own. Weird!!
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  #97  
Old 09-02-2012, 10:32 PM
Rivethead Rivethead is offline
 
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Just checked this thread out for the first time. I'd be looking at my prop flange. You don't mention where the engine came from. I'd be doubly suspicious of the flange if it were a used or rebuilt engine. Very dangerous if it is the flange runout for it could eventually snap the crank in two.
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  #98  
Old 09-04-2012, 10:11 AM
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flyenforfun flyenforfun is offline
 
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Quote:
Originally Posted by Rivethead View Post
Just checked this thread out for the first time. I'd be looking at my prop flange. You don't mention where the engine came from. I'd be doubly suspicious of the flange if it were a used or rebuilt engine. Very dangerous if it is the flange runout for it could eventually snap the crank in two.
Brand new engine from Lycoming. Hopefully this isnt the issue..
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  #99  
Old 09-04-2012, 10:13 AM
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flyenforfun flyenforfun is offline
 
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Quote:
Originally Posted by thinkn9a View Post
Is it REALLY RPM related.. or is it SPEED related?

I'm confused that you had it dynamically balanced,... yet you have vibration,... seems to me it would have indicated and issue if you had that done. (vibration not able to be corrected). Does it shake "on the ramp" or only while flying?

So,... is it something else,...a.) wing/fuse -seal/gasket loose? (been known to scare the bejimminies out of folks, when it wiggles out and starts shaking) b.) seal between cowl and inlet ramps not "fair and smooth",.. and shaking with air across it c.) wing walk non-skid pad coming loose and shaking air/wing d.) your other tires were out of round,... how does the tail wheel look,.. any abuse to it causing out of round? (as you found out, .. out of round tires shake) e.) all the access panels on tight? sure? f.) what about the bottom of the cowling... any chance the FAB is rubbing or hitting at some point.... they are known to have some fit-up and tweaking required depending on engine, carb/TB, and cowling arrangement. g.) something not "strain relieved" running to the engine and up against the engine mount or firewall,... causing a "sound short" (and getting ready to fail in the future)

It really is amazing how little it takes to shake the plane.

Read about a Reno racer that spent a LONG time with a experienced crew, before they finally traced a problem down to a cover not sitting fair.

keep plugging and keep us informed,... as you can tell,... you have us stumped,.. and we need some answers..
I say RPM and not speed because if I quickly pull my engine to idle from cruise speed and power, the vib stops.

How about this for an update.. if I put my toes down on the floor at the base of the pedals, I feel a VERY strong vibration in my toes. Haven't felt this before because my heels are further back on the floor. Exhaust pulses?
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  #100  
Old 09-04-2012, 10:45 AM
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Ironflight Ironflight is offline
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Quote:
Originally Posted by flyenforfun View Post
I say RPM and not speed because if I quickly pull my engine to idle from cruise speed and power, the vib stops.

How about this for an update.. if I put my toes down on the floor at the base of the pedals, I feel a VERY strong vibration in my toes. Haven't felt this before because my heels are further back on the floor. Exhaust pulses?
I think you have a lead to follow here Matt. Do you have turn-down tips on yor exhaust pipes? If not, get a set (Vetterman has them) and see if it makes a difference.
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