To all concerned about flutter: I am going to quote from a professional study regarding the Lancair: "Unlike control surface flutter, which is typically managed by counterweighting the surfaces and/or modifying their control actuation systems, the flutter identified here is with the fuselage itself,". The excerpt is from a study which cab be found at: http://www.lancair.net/flutter.html Joe ----- Original Message ----- From: "joe" <feg...@earthlink.net> To: "KRnet" <kr...@mylist.net> Sent: Thursday, March 18, 2004 12:16 PM Subject: Re: KR>Flutter
> 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 > > > _______________________________________ > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html
