Winglet Flutter was : Re: REFLECTOR: 1st flight N2084D

[Scott Derrick]

I've had winglet flutter and lived to walk away. Later we actually induced 
it on purpose, (very controlled flight) to verify it really was winglet 
flutter.

Mine would only occur at 180+ knots indicated.  It was completely my fault. 
While trying to get the ball in the center I had "unshimmed" the trailing 
edge of the right rudder so it was about 1/8 of an inch inboard of the 
trailing edge of the winglet.  Ball was dead on center and I flew for a 
month before getting the indicated speed up high enough to get it to flutter.

With bonehead type induced flutter(mine)  pressing your foot on the rudder 
stops it immediately, slowing down below 180 KIAS would also stop it.  With 
the rudder shimmed to be even with the winglet on the trailing edge I dove 
to 215 KIAS with no flutter.  Sure get a hell of a lot of air noise at 215 
KIAS!

Its a scary thing to look out the window and see the wing bending up and 
down that much and that fast!!!!

Scott


At 03:28 PM 8/1/2004, you wrote:
>There is nothing to measure now.  Everything looks ok.  My estimate is 
>that the entire winglet was at least one and a half inches out and one and 
>a half inches in (3 inches total) at the top.  The rudder was full 
>deflection.  The wing was all over the place.
>----- Original Message -----
>From: <mailto:michalk at awpi.com>Brian Michalk
>To: <mailto:reflector at tvbf.org>Velocity Aircraft Owners and Builders list
>Sent: Sunday, August 01, 2004 1:05 PM
>Subject: RE: REFLECTOR: 1st flight N2084D
>
>Do you think you could measure the inboard deflection, and maybe take a 
>picture or two to help out the rest of us?
>
>You've got a good example of flutter, and lived to tell about it.  You can 
>document this and we can maybe learn something from it.
>
>
>  Brian Michalk  <<http://www.michalk.com>http://www.michalk.com>
>Life is what you make of it ... never wish you had done something.
>Aviator, experimental aircraft builder, motorcyclist, SCUBA diver
>musician, home-brewer, entrepreneur and barely single
>
>-----Original Message-----
>From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]On 
>Behalf Of dean fitzbag
>Sent: Sunday, August 01, 2004 10:50 AM
>To: reflector
>Subject: REFLECTOR: 1st flight N2084D
>
>I made my first flight this morning.  It took me 21 months to build my 
>standard RG with no fast builds.
>
>The flight started fine with only a little over zealous elevator at 
>liftoff.   It handled well and before turning cross wind I retracted the 
>gear.  The airspeed was about 110 knots.  As I turned downwind I heard a 
>few sounds that sounded like an engine miss.  It quickly got very 
>rough.  I thought the engine was failing.  The aircraft was shaking 
>badly.  I declared an emergency and asked everyone to clear the area.  I 
>reduced power right away to improve chances of staying up longer and 
>lowered the gear.  While looking at the airport to plan which runway to 
>set up for, I saw out of the corner of my that my problem was left rudder 
>flutter.  It was really shaking everything.  Then as the airplane slowed 
>to  100 knots the ride smoothed out.  At 80 knots it was very smooth.  So 
>I continued to fly a normal approach and landing.  I'll call the factory 
>tomorrow, but my guess is that a shim will be recommended.
>
>The factory was very helpful during building process.  Mike Pollack did my 
>EAA inspections and was provided very useful advice.
>
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