Dear Steve, I know when I'm licked. However my comments are from real life experiences. Somewhat different the aileron control surfaces and the elevator trim tabs were repaired with bondo which deformed them during high speed flight. The report results read "malformation". The other comment I thought to be part of every aviators curriculum that exceed Vne and you become a test pilot.
PS The aircraft involved was my comanche 250. ----- Original Message ----- From: "Stephen Jacobs" <ask...@microlink.zm> To: "'KRnet'" <kr...@mylist.net> Sent: Thursday, March 18, 2004 11:52 AM Subject: KR>Flutter > I respect airplanes as much as I love them, so when they talk to me I > listen. Not many things in airplanes scare me, but when they do - I > feel compelled to tell fellow aviators. > > We have talked about carb ice - I have told you what I know and I will > be happy if my input helps one person avoid a bad day. > > Carb ice (at worst), will turn your airplane into a glider - gliders > still fly. Flutter is something very different - it could leave you > sitting on a wingless brick. Not many of the folks that have > experienced flutter are still around - it is difficult to describe the > suddenness and violence of this phenomenon. > > My concern about flutter has resulted in 15 years of listening, reading, > testing and trying. I do not wish to enter into debate on any of this - > take it or leave it: (Mark, Dana & Larry exempted) > > This is KRnet, so my comment applies to everything we are likely to > address - however, I would apply the same rationale to a Pietenpol. > > IN EVERY CASE > > 1. Mass balance (statically) all control surfaces. This is not > critical to the nth degree - just ensure that EVERY completed control > surface sort of "hangs level" with the pushrod disconnected. Yes, the > rudder is a problem - figure a way to turn the bird on its side - or do > the VStab before you mount it. I prefer distributed balance weight > where possible - not all in one place. Aerodynamic balance tabs are > great - they provide one more place to put some of the counter weight. > > Get the ballast as far fwd (of the hinge-line) as possible to reduce the > amount required. All KR control surfaces are aft of CG, so keep added > weight to the essential minimum - it affects CG. > > 2. Zero slop in the control linkages and hinges (including trim tab). > > 3. Perfect alignment between the moving control surface and the fixed > surface - avoid a step-down between the fixed and the trailing (movable) > surface - this introduces turbulence at the TE of the fixed surface, > i.e. turbulence over the control surface - I believe that this provokes > flutter. > > If in doubt, make the moving surface a tad thicker than the fixed > surface. > > There has been good advice from some of the netters - viz: > > = apples and oranges are being mixed here > = Flutter can happen at any speed > = more factors limiting the Vne than elevator flutter > = Flutter can destroy an aircraft in flight! > > > I have also seen information from other netters that makes no sense at > all - viz.: > > = However, any malformation of the elevator, depends on the > malformation. Exceeding Vne coupled with excess loading factor and all > bets are off. > > > Take care > Steve > askies(At)microlink.zm > > > > > > _______________________________________ > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html
