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  #101  
Old 09-04-2012, 11:01 AM
Pat Stewart Pat Stewart is offline
 
Join Date: Jan 2005
Location: Granbury Texas
Posts: 1,136
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Have you checked the wheel nut on each side to see if the tires rotate too freely, this could cause shimmy on landing and I have witnessed tires rotating at high speeds in flight which may even cause airframe vibration.
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  #102  
Old 09-04-2012, 01:11 PM
E. D. Eliot E. D. Eliot is offline
 
Join Date: Dec 2005
Location: San Pedro
Posts: 1,016
Default Get some help

Get someone (if you already haven't done so) who is a long time RV pilot to fly with you. Why extend this agony any longer?
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  #103  
Old 09-04-2012, 02:30 PM
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flyenforfun flyenforfun is offline
 
Join Date: Aug 2009
Location: Wilmington DE
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Quote:
Originally Posted by E. D. Eliot View Post
Get someone (if you already haven't done so) who is a long time RV pilot to fly with you. Why extend this agony any longer?
I extended it this long because I was still in phase 1 and cannot take passengers. I just finished the 40 hours on Saturday and its been raining ever since. Figures.
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  #104  
Old 09-04-2012, 02:30 PM
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flyenforfun flyenforfun is offline
 
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Quote:
Originally Posted by Pat Stewart View Post
Have you checked the wheel nut on each side to see if the tires rotate too freely, this could cause shimmy on landing and I have witnessed tires rotating at high speeds in flight which may even cause airframe vibration.
Tire changed solved the wheel shimmy problem, I think the old ones were just permanently flat spotted from sitting for so long. Thanks though.
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Matt Giordano Sr. and Jr.
RV-8 - N861MM
Wilmington, DE
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  #105  
Old 09-04-2012, 02:32 PM
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flyenforfun flyenforfun is offline
 
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Originally Posted by Ironflight View Post
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.
I do not have turn down tips, maybe I will give that a try. This area will be my next shot at finding a solution.
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RV-8 - N861MM
Wilmington, DE
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  #106  
Old 09-04-2012, 03:01 PM
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Bob Kuykendall Bob Kuykendall is offline
 
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Location: Douglas Flat, CA
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Quote:
Originally Posted by flyenforfun View Post
I do not have turn down tips, maybe I will give that a try. This area will be my next shot at finding a solution.
The tunnel skin seems to collect a lot of acoustical energy even with the turned down tips, so it's probably even worse with straight tips. Many builders reinforce the tunnel skin with internal or external stiffeners, and they still tend to vibrate enough to crack even on relatively low-hour airframes.

So I'm with Paul on this one. Either get the turned-down tips or prototype some scheme to deflect the exhaust away from the tunnel skin.

Thanks, Bob K.
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  #107  
Old 09-06-2012, 08:20 AM
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flyenforfun flyenforfun is offline
 
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Location: Wilmington DE
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Quote:
Originally Posted by Bob Kuykendall View Post
The tunnel skin seems to collect a lot of acoustical energy even with the turned down tips, so it's probably even worse with straight tips. Many builders reinforce the tunnel skin with internal or external stiffeners, and they still tend to vibrate enough to crack even on relatively low-hour airframes.

So I'm with Paul on this one. Either get the turned-down tips or prototype some scheme to deflect the exhaust away from the tunnel skin.

Thanks, Bob K.
Anyone know where I can buy the correct turn down tips? Cant seem to find anywhere to buy on vettermans website
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  #108  
Old 09-06-2012, 09:07 AM
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Ironflight Ironflight is offline
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Location: Dayton, NV
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Quote:
Originally Posted by flyenforfun View Post
Anyone know where I can buy the correct turn down tips? Cant seem to find anywhere to buy on vettermans website
Just call him on the "teleophone"....
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RV-8 - N188PD - "Valkyrie"
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  #109  
Old 09-06-2012, 11:01 AM
eison eison is offline
 
Join Date: Jul 2007
Location: Irvine, CA
Posts: 28
Default Worth a try?

My grumman tiger with a 360 engine produces a vibration that I can feel through the airfram if the engine is not leaned properly. If it is rich the plane will feel like it is pulsing a little. When it is leaned too much, then it stumbles slightly and you can feel that through the airframe as well.

I don't have any fancy engine monitoring equipment, but you might just play with the leaning and see if it has an impact. I can tell blindfolded if the engine is leaned correctly.
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  #110  
Old 09-07-2012, 05:26 AM
bignose bignose is offline
 
Join Date: Sep 2010
Location: Sao Paulo, Brasil
Posts: 72
Default Cowl baffles

I had similar vibration issues on my RV9A, they began always when building up airspeed greater than 95 kt. When I put back the upper cowl after maintenance, the left baffle crushed backwards instead of forward. Building up speed, this peace of rubber drummed against the cowl like a flag in the wind. Just stick your hand into the oil check door, or look inside with the help of a flashlight and see if the baffles are bent forward.

Last edited by bignose : 09-07-2012 at 06:26 AM.
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