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Kitfox Control Surface Flutter Mitigation
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Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Thu Apr 23, 2009 5:39 am Post subject: Kitfox Control Surface Flutter Mitigation

I’m off the water generally in less than 500 ft reasonably calm conditions full gross.  I can “land” in less than 300 ft for sure.  2/3 flap.  

   

Noel  

     

From: owner-kitfox-list-server(at)matronics.com [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of W Duke

 Sent: Thursday, April 23, 2009 9:31 AM

 To: kitfox-list(at)matronics.com

 Subject: Re: Re: Kitfox Control Surface Flutter Mitigation  

  

           

I use full flaps to land short.  Full flap has not   scared me.  Maybe I don't know enough to be scared but I use full flaps   almost all the time. Again, I usually do not use any flap until on   final.  Try getting slow at altitude to get the feel for it.  (I   may not be able afford new gear for you right now.)  There is a change   in the feel of the plane that takes a little getting used to.  Nose is   very high and once you get slow enough it feels almost like you are going   down more than forward.  But there is still elevator authority to   flare.  Not having that extra speed at flare really shortens the glide   and landing distance.

   

   Maxwell Duke

   S6/TD/IO240

   Dublin, GA

   

   --- On Wed, 4/22/09, n85ae <n85ae(at)yahoo.com> wrote:   

From: n85ae   <n85ae(at)yahoo.com>

   Subject: Re: Kitfox Control Surface Flutter Mitigation

   To: kitfox-list(at)matronics.com

   Date: Wednesday, April 22, 2009, 8:57 PM    	  Quote: 	
		  --> Kitfox-List message posted by: "n85ae" <n85ae(at)yahoo.com> Maxwell - I take it you're doing this with 1 notch of flaperons? Winds permitting Imight work on this tommorrow after work. I generally slip it in around60, and then start flaring after the slip. 50 seems slow, but still there'sprobably about 10 mph left. If I bend the gear, I'll blame you.  Definetly don't want to do that if it's gusting at all. Even with my 	
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_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

Fox5flyer
Guest

Posted: Thu Apr 23, 2009 7:17 am Post subject: Kitfox Control Surface Flutter Mitigation

Jeff, mine acts the same way.  I don't often use the full flaps for the same 

reasons.  Too squirrely.  It feels like the ailerons are blocking out the 

rudder in some way because I have to use about twice as much rudder to keep 

it straight.  If things are calm and I'm on short final I'll pull in full 

flaps to slow my landing speed to get in short, but only when I absolutely 

need it.  Otherwise I always use first notch.

I'll take second dibs on the gear.

Deke Morisse

Mikado Michigan

S5/Subaru/CAP 405+ TT

"The aim of an argument or discussion should not be victory, but progress."

- Joseph Joubert



 	  Quote: 	
		   



 Maxwell -



 I'm comfortable with the nose high attitude the plane gets when slow, so

 that's no problem.



 What I don't like is the full flaperons. I think at full nose up trim I 

 still have

 to hold a lot of back stick, plus it really screws up the roll control. 

 I'll let

 you be the expert on this subject.



 Can we just start calling you Madmax on the forum from now on?



 By the way, I think you have the same gear I have, so ... If you're

 lacking funds you can just ship me yours.



 Regards,

 Jeff





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p 40893#240893

n85ae

Joined: 14 Mar 2007
Posts: 403

Posted: Thu Apr 23, 2009 9:55 am Post subject: Re: Kitfox Control Surface Flutter Mitigation

Deke - 



I flew mine a few times, and played with the second notch, but honestly

I do not like the handling of the plane and it makes me feel distinctly

uncomfortable with them like that. It uses all the trim just to fly it, and

the yaw, and roll control  feel's weird, and spooky.



I wouldn't go so far as to safe it's not safe to fly the plane that way

but I sure feel insecure when they are deployed that much.



Regards,

Jeff

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Thu Apr 23, 2009 10:33 am Post subject: Kitfox Control Surface Flutter Mitigation

There is a point that I should make.  When I got my plane I checked on the

adjustment of the ailerons.  I didn't like the idea of a binding in the

mixing box when the ailerons were fully deflected.  I  decided to set my

adjustment so that there would be no binding.  That gives me a degree or two

of reflex of my ailerons.  Yes my ailerons are nowhere as deflected as they

were but then again there is also no way I can get my ailerons into reverse

control.



Noel



--

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

Dick Maddux

Joined: 24 Jun 2008
Posts: 516
Location: Milton, Fl

Posted: Thu Apr 23, 2009 12:59 pm Post subject: Kitfox Control Surface Flutter Mitigation

Speaking of flutter, I just returned from Lakeland. They had a Zenith 650 at the show and the hinges for the ailerons on that plane was the top wing skin ! There are no hinges ! Now perhaps I am getting the wrong picture here, but I like hinges. What happens when you bend aluminum sheet over and over and over. Eventualy it will fracture and break . Yeah ,I know it will take a while but I could not get close enough to the (crowds) Zenith folks to ask why they would do that.

  I talked to an engineer at another mfg and asked why they would do that and he made sounds like a baby chicken (with a c)

                                                    Dick Maddux

                                                    Fox 4-1200

                                                     Pensacola,Fl 

  Big savings on Dell XPS Laptops and Desktops!

  [quote][b]

rjdaugh

Joined: 30 Aug 2006
Posts: 195

Posted: Thu Apr 23, 2009 7:32 pm Post subject: Kitfox Control Surface Flutter Mitigation

Jeff,

I wonder if you have your flaps setup correctly.  I use full flaps a lot.

About the only times I don't use full flaps is if there is a lot of wind -

then I use half flaps.  I also slip a lot.  I need to try Maxwells

technique.  I have some, but always chicken out and give a good shot of

power about 30' from ground.



Another item that I really like for getting in short is a lift reserve

instrument.  Having this really changed the way I fly.  I do not pay

attention to the airspeed gauge much any more and I usually climb out at a

much higher angle than I ever dared to before.



Randy

Series 5/7

912S, WarpDrive taper tip



--

_________________
Randy
Kitfox 5/7 912S
Black Hills, South Dakota

matronics(at)bob.brennan.
Guest

Posted: Fri Apr 24, 2009 3:21 am Post subject: Kitfox Control Surface Flutter Mitigation

Randy - 



Excuse my ignorance but what exactly is a "lift reserve instrument"?

Obviously I can surmise from the name what it does, and it sounds very

useful, but I have never heard of such a thing. I want one!



Bob Brennan - N717GB

ELSA Repairman, inspection rated

1991 UK Model 2 ELSA Kitfox taildragger

Rotax 582 with 3 blade GSC prop

Wrightsville Pa 



--

Patrick.Best(at)telus.com
Guest

Posted: Fri Apr 24, 2009 5:08 am Post subject: Kitfox Control Surface Flutter Mitigation

Chris Heintz wrote an  article about the use of a skin as a hinge.

  

 Design and Application of the

ZODIAC's Hingeless  Aileron

  

 http://www.zenithair.com/kit-data/ht-aileron.html

  

 

 

   From: owner-kitfox-list-server(at)matronics.com  [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of  Catz631(at)aol.com

Sent: Thursday, April 23, 2009 4:59  PM

To: kitfox-list(at)matronics.com

Subject: Re: Kitfox-List:  Kitfox Control Surface Flutter Mitigation

 

 Speaking of flutter, I just returned from Lakeland. They had a Zenith 650  at the show and the hinges for the ailerons on that plane was the top  wing skin ! There are no hinges ! Now perhaps I am getting the wrong  picture here, but I like hinges. What happens when you bend aluminum sheet over  and over and over. Eventualy it will fracture and break . Yeah ,I know it will  take a while but I could not get close enough to the (crowds) Zenith folks to  ask why they would do that.

  I talked to an engineer at another mfg and asked why they would do  that and he made sounds like a baby chicken (with a c)

                                                     Dick Maddux

                                                    Fox  4-1200

                                                      Pensacola,Fl 



  [url=http:%2F%2Fad.doubleclick.net%2Fclk%3B214133440%3B36002254%3Bj]Big  savings on Dell XPS Laptops and Desktops![/url] 

[quote]



ttp://www.matronics.com/Navigator?Kitfox-List

ics.com

.matronics.com/contribution



[b]

n85ae

Joined: 14 Mar 2007
Posts: 403

Posted: Fri Apr 24, 2009 6:14 am Post subject: Re: Kitfox Control Surface Flutter Mitigation

The plane is different with the 912



Yes they are set correctly. It may just be the heavier airplane. I'm at 

967 empty weight with the the 240B. It's not an issue that I can't land

plane short, I can. The heavier nose airplane requires full trim which

means the tail incidence is all the down in the front. The roll control

is restricted, etc. So I don't use the second notch. The plane to me just

feels horrible handling in that configuration.

 

 	  rjdaugh wrote: 	
		  Jeff,

I wonder if you have your flaps setup correctly.  I use full flaps a lot.

About the only times I don't use full flaps is if there is a lot of wind -

then I use half flaps.  I also slip a lot.  I need to try Maxwells

technique.  I have some, but always chicken out and give a good shot of

power about 30' from ground.



--

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Fri Apr 24, 2009 6:27 am Post subject: Kitfox Control Surface Flutter Mitigation

It is also known as an AOA instrument... ( angle of Attack )



Noel



--

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Fri Apr 24, 2009 6:43 am Post subject: Kitfox Control Surface Flutter Mitigation

The zenith design of having a hingeless attachment of the ailerons is quite well proven.  The length of the attach point, the grain of the metal and the smallmovement the ailerons make all combine to make it very safe.  That is one part of the plane that is secure.  Apparently there are reasons for and against having the hinged and hingeless ailerons.  I’m suer the people at Zenith will be more than happy to let you in on all features of both systems.  

   

Noel  

       

From: owner-kitfox-list-server(at)matronics.com [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of Catz631(at)aol.com

 Sent: Thursday, April 23, 2009 6:29 PM

 To: kitfox-list(at)matronics.com

 Subject: Re: Kitfox Control Surface Flutter Mitigation  

  

  

     

Speaking of flutter, I just returned from Lakeland. They had a Zenith 650 at the show and the hinges for the ailerons on that plane was the top wing skin ! There are no hinges ! Now perhaps I am getting the wrong picture here, but I like hinges. What happens when you bend aluminum sheet over and over and over. Eventualy it will fracture and break . Yeah ,I know it will take a while but I could not get close enough to the (crowds) Zenith folks to ask why they would do that.  

    

 I talked to an engineer at another mfg and asked why they would do that and he made sounds like a baby chicken (with a c)  

    

                                                   Dick Maddux  

    

                                                   Fox 4-1200  

    

                                                    Pensacola,Fl   

  

       

  

Big savings on Dell XPS Laptops and Desktops!   	  Quote: 	
		    http://www.matronics.com/Navigator?Kitfox-List 	
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_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

matronics(at)bob.brennan.
Guest

Posted: Fri Apr 24, 2009 6:54 am Post subject: Kitfox Control Surface Flutter Mitigation

So can you derive "lift reserve" from angle-of-attack? I know that it's the

AoA that determines when a wing will stall, not the airspeed, but on flare

we hold the stick back for a high AoA to bleed off airspeed and hopefully

maintain a constant close distance to the ground, but during that time the

"lift reserve" is diminishing until the airplane settles onto the runway.

Would an AoA instrument give an indication that correlates to that,

specifically during flare?



bob 



--

Guy Buchanan

Joined: 16 Jul 2006
Posts: 1204
Location: Ramona, CA

Posted: Fri Apr 24, 2009 7:29 am Post subject: Kitfox Control Surface Flutter Mitigation

At 06:06 AM 4/24/2009, you wrote:

 	  Quote: 	
		  Chris Heintz wrote an article about the use of a skin as a hinge.


	


An interesting article, as much for what it omits as for what it 

includes. Though Mr. Heintz has done a great job of analyzing the 

flexural properties of the hinge he says nothing whatsoever about its 

lack of transverse stiffness. 3/4" of 0.016" aluminum has very little 

shear stiffness. This allows the leading edge of the aileron to 

translate perpendicular to the skin surface. I'm guessing I could get 

the example leading edge to translate vertically +/- 1/16" without 

much trouble. If that leading edge happens to be in front of the 

aileron's CG you have a recipe for flutter. That's why most designers 

use piano hinges. They locate the leading edge not only in the plane 

of the skin, but perpendicular to the skin line as well.

Guy Buchanan

San Diego, CA

K-IV 1200 / 582-C / Warp / 300 hrs. and counting

_________________
Guy Buchanan
Deceased K-IV 1200
A glider pilot too.

lcfitt(at)sbcglobal.net
Guest

Posted: Fri Apr 24, 2009 7:43 am Post subject: Kitfox Control Surface Flutter Mitigation

Bob,



I think that an angle of attack indicator and lift reserve indicator do 

pretty much the same thing.  The typical angle of attach instrument uses a 

small vane that mechanically determines the angle of attack.  The lift 

reserve indicator uses differential pressure from two ports on a short wand 

to determine the same thing.  I have always thought of the naming as just a 

marketing thing to differentiate the mechanical from the differential 

pressure approach to the measurement.  There is one design that uses small 

holes at different points of the leading edge if the wing to determine 

differential pressures.



Regarding my installation.  I plan on mounting the readout gauge below the 

glare shield with a a mirror to correct the image before it bounces off a 

clear glass reflector, just like the heads up displays on military aircraft. 

I hope to have it exactly in my forward vision during the critical 

attitudes.



Lowell



---

n981ms(at)yahoo.com
Guest

Posted: Tue Apr 28, 2009 4:55 am Post subject: Kitfox Control Surface Flutter Mitigation

Been off the list for a few days while at SNF.  There is certainly adverse yaw with full flap roll control.  One can see why when at full flap a right aileron input results in a little more down on the left flaperon and therefore more left drag and up flaperon on the right with less drag.  Now that we are using words like spooky I am thinking I will go back out and compare  1 vs 2 notches and see.  I just almost always use full flaps lately.  Certainly I wish there was more up trim  but I need more up for even one notch of flap.  John McBean makes something to help with this.

     By the way.  It was good to see John and Kitfox at Sun N Fun again.  For me, if they had not had a presence there when I was kit shopping I would probably have not built a Kitfox.  I hope they sell a bunch of airplanes and continue to have a presence in the east.



Maxwell Duke

S6/TD/IO240

Dublin, GA



--- On Thu, 4/23/09, n85ae <n85ae(at)yahoo.com> wrote:



  	  Quote: 	
		  From: n85ae <n85ae(at)yahoo.com>

Subject: Kitfox-List: Re: Kitfox Control Surface Flutter Mitigation

To: kitfox-list(at)matronics.com

Date: Thursday, April 23, 2009, 1:55 PM



 	  Quote: 	
		  --> Kitfox-List message posted by: "n85ae" <n85ae(at)yahoo.com>



Deke - 



I flew mine a few times, and played with the second notch, but honestly

I do not like the handling of the plane and it makes me feel distinctly

uncomfortable with them like that. It uses all the trim just to fly it, and

the yaw, and roll control  feel's weird, and spooky.



I wouldn't go so far as to safe it's not safe to fly the plane that way

but I sure feel insecure when they are deployed that much.



Regards,

Jeff





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=240930#240930





	
	


         [quote][b]

patreilly43(at)hotmail.co
Guest

Posted: Tue Apr 28, 2009 1:50 pm Post subject: Kitfox Control Surface Flutter Mitigation

Hey Guys C Lowell Fitt has an elevator trim tab installation that if you talk nice to him he will sell you the parts to install it yourself. I'm using the electric servos as he does. But C you could easily adapt it to cable control and with a little work you'll only spend peanuts for the whole setup.

  

 Pat Reilly

 Mod 3 582 Rebuild

 Rockford C IL

 

  Date: Tue C 28 Apr 2009 05:46:16 -0700

From: n981ms(at)yahoo.com

Subject: Re: Re: Kitfox Control Surface Flutter Mitigation

To: kitfox-list(at)matronics.com



     Been off the list for a few days while at SNF.  There is certainly adverse yaw with full flap roll control.  One can see why when at full flap a right aileron input results in a little more down on the left flaperon and therefore more left drag and up flaperon on the right with less drag.  Now that we are using words like spooky I am thinking I will go back out and compare  1 vs 2 notches and see.  I just almost always use full flaps lately.  Certainly I wish there was more up trim  but I need more up for even one notch of flap.  John McBean makes something to help with this.

     By the way.  It was good to see John and Kitfox at Sun N Fun again.  For me C if they had not had a presence there when I was kit shopping I would probably have not built a Kitfox.  I hope they sell a bunch of airplanes and continue to have a presence in the east.



Maxwell Duke

S6/TD/IO240

Dublin C GA



--- On Thu C 4/23/09 C n85ae <n85ae(at)yahoo.com> wrote:



  	  Quote: 	
		  From: n85ae <n85ae(at)yahoo.com>

Subject: Re: Kitfox Control Surface Flutter Mitigation

To: kitfox-list(at)matronics.com

Date: Thursday C April 23 C 2009 C 1:55 PM



 	  Quote: 	
		  --> Kitfox-List message posted by: "n85ae" <n85ae(at)yahoo.com>



Deke - 



I flew mine a few times C and played with the second notch C but honestly

I do not like the handling of the plane and it makes me feel distinctly

uncomfortable with them like that. It uses all the trim just to fly it C and

the yaw C and roll control  feel's weird C and spooky.



I wouldn't go so far as to safe it's not safe to fly the plane that way

but I sure feel insecure when they are deployed that much.



Regards C

Jeff





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=240930#240930





	
	


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