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Turtle deck vibration

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Fox5flyer
Guest

Posted: Fri Sep 08, 2006 3:14 am Post subject: Turtle deck vibration

My S5 has always been a pretty smooth flyer.   However, one thing that has always bothered me and is causing some wear is the  turtle deck vibrating at cruise speeds, presumably due to some turbulent  air.  I can't hear it, but I can see it in the rear view mirror and the  vibration is causing wear on the contact surfaces.  I am thinking that  perhaps some vortex generators might smooth out the air flow and help to either  solve or ameliorate the problem.  I think it might work, but I don't  know where to place them.  Has anybody tried this with any  success?

 Deke

  

   [quote][b]

lcfitt(at)sbcglobal.net
Guest

Posted: Fri Sep 08, 2006 6:12 am Post subject: Turtle deck vibration

Deke,  I get a little bit of pulsing evident in the fabric under the wing 

from time to time.  I have attributed it to the prop pulses in the prop wash 

area.  Keep us posted on what you find out.



Lowell

---

smokey_bear_40220(at)yaho
Guest

Posted: Fri Sep 08, 2006 10:34 am Post subject: Turtle deck vibration

Same with me Deke,



The only vibrating part seems to be the turtledeck.



I wonder if the air is seperating over the windscreen,

or the strakes on the side of the turtledeck are

vibrating in the turbulence from the draggy pocket

behind the aft spar.  Maybe both.  I'd like to attend

to both myself, when I get the time.



The VG's are easy to do.  You can test them by taping

them down with enough good clear tape.  Try them 6"

between pair centers.  The pairs are 1" apart and set

17 degrees off in opposite directions, leading edge

closest.  Run a straight edge parallel to the wing

leading edge 6" back and put the VG backs against it. 

A cardboard template makes it easier to set the 17

degree angle and distances.



You can adjust the distance back from the leading edge

and test fly to get the best results.  Somewhere

between 4" and 8" back should do it IMHO.



I expect to retire at the end of the year and maybe

fly all for fun then.    Then I can do a lot more

of this fun testing stuff.  Not there just yet.



Kurt S.  S-5/NSI turbo



--- Fox5flyer <morid(at)northland.lib.mi.us> wrote:



 	  Quote: 	
		   My S5 has always been a pretty smooth flyer. 

 However, one thing that has always bothered me and

 is causing some wear is the turtle deck vibrating at

 cruise speeds, presumably due to some turbulent air.

  I can't hear it, but I can see it in the rear view

 mirror and the vibration is causing wear on the

 contact surfaces.  I am thinking that perhaps some

 vortex generators might smooth out the air flow and

 help to either solve or ameliorate the problem.  I

 think it might work, but I don't know where to place

 them.  Has anybody tried this with any success?

 Deke


	


__________________________________________________

mino2(at)verizon.net
Guest

Posted: Fri Sep 08, 2006 1:04 pm Post subject: Turtle deck vibration

Deke,



I wonder if the glass area in the turtle deck had a slight bow to it, it 

wouldn't oilcan and vibrate.  I purchased mine, a one piece affair, an it 

came with about a one inch crown on it.  The instructions said it was to 

keep it from vibrating.  Can't be sure as I'm still not flying yet.



Fly safe,



Nelson

do not archive

---

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Fri Sep 08, 2006 4:26 pm Post subject: Turtle deck vibration

I got mine from LP Aeroplastics, and it is domed and does not vibrate. 

Like you said, Nelson, it has about a 1" dome to the "glass".  This 

required that I  remove the hinge, therefore the whole 'deck has to be 

dealt with as an unbendable whole and not hinging it any more....but it 

doesn't leak, either.



Lynn



Lynn

On Friday, September 8, 2006, at 05:03  PM, Nelson Goguen wrote:



[quote] 



 Deke,



 I wonder if the glass area in the turtle deck had a slight bow to it, 

 it wouldn't oilcan and vibrate.  I purchased mine, a one piece affair, 

 an it came with about a one inch crown on it.  The instructions said 

 it was to keep it from vibrating.  Can't be sure as I'm still not 

 flying yet.



 Fly safe,



 Nelson

 do not archive

 ---

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

Fox5flyer
Guest

Posted: Sat Sep 09, 2006 3:28 am Post subject: Turtle deck vibration

Thanks Kurt.  I suspect most of them vibrate, but the pilot just doesn't

know it.  It isn't bad.  It just vibrates enough that it causes black dust

around the edges where it contacts the wings.  Perhaps this winter when I

have the time and the airplane is down for annual I can conjure up

something.  I'd like to do the VGs across the whole wing, but I'm concerned

about the loss of speed.  That's about the only thing that's held me back.

Deke

 	  Quote: 	

 Same with me Deke,

 The only vibrating part seems to be the turtledeck.

 I wonder if the air is seperating over the windscreen,

 or the strakes on the side of the turtledeck are

 vibrating in the turbulence from the draggy pocket

 behind the aft spar.  Maybe both.  I'd like to attend

 to both myself, when I get the time.

 The VG's are easy to do.  You can test them by taping

 them down with enough good clear tape.  Try them 6"

 between pair centers.  The pairs are 1" apart and set

 17 degrees off in opposite directions, leading edge

 closest.  Run a straight edge parallel to the wing

 leading edge 6" back and put the VG backs against it.

 A cardboard template makes it easier to set the 17

 degree angle and distances.

 You can adjust the distance back from the leading edge

 and test fly to get the best results.  Somewhere

 between 4" and 8" back should do it IMHO.

 I expect to retire at the end of the year and maybe

 fly all for fun then.    Then I can do a lot more

 of this fun testing stuff.  Not there just yet.

 Kurt S.  S-5/NSI turbo

 --- Fox5flyer <morid(at)northland.lib.mi.us> wrote:

 > My S5 has always been a pretty smooth flyer.

 > However, one thing that has always bothered me and

 > is causing some wear is the turtle deck vibrating at

 > cruise speeds, presumably due to some turbulent air.

 >  I can't hear it, but I can see it in the rear view

 > mirror and the vibration is causing wear on the

 > contact surfaces.  I am thinking that perhaps some

 > vortex generators might smooth out the air flow and

 > help to either solve or ameliorate the problem.  I

 > think it might work, but I don't know where to place

 > them.  Has anybody tried this with any success?

 > Deke

 __________________________________________________

Fox5flyer
Guest

Posted: Sat Sep 09, 2006 3:51 am Post subject: Turtle deck vibration

Thank you Nelson.  You're probably correct because a slight bow would give

the turtle deck a small amount of lift thereby putting some constant tension

on it.  My turtle deck is in great shape and I'm not quite ready to replace

it yet so I'm considering the VGs first to see what will happen.  My gut

feeling is that it will work.

Deke



[quote]

 Deke,



 I wonder if the glass area in the turtle deck had a slight bow to it, it

 wouldn't oilcan and vibrate.  I purchased mine, a one piece affair, an it

 came with about a one inch crown on it.  The instructions said it was to

 keep it from vibrating.  Can't be sure as I'm still not flying yet.



 Fly safe,



 Nelson

 do not archive

 ---

dave(at)cfisher.com
Guest

Posted: Sat Sep 09, 2006 3:58 am Post subject: Turtle deck vibration

Deke ,



I have  a vibration at run up on turtle deck  but nothing in flight.   I 

have Vgs  in shop but have not used yet.

Kitfox IV  works good now with full elevator authority and great slow speed 

performance.  But my Kitfox is about 550 lbs so the weight helps alot.

I think I will try them some time as well.   I have heard that a few vgs 

placed on the back of the windshield near  the turtle deck  will stop the 

vibrations.



I have harrison designs ones here .   You can get I think 100 of them for ? 

under 100$  ithink.  Plus just try with 2 sided carpet tape.



Dave

---

smokey_bear_40220(at)yaho
Guest

Posted: Sat Sep 09, 2006 4:57 pm Post subject: Turtle deck vibration

Hi Deke,



When I tested the VG's on my plane 2 years back, I

found that the max speed varied a bit with position. 

Closer to the leading edge seemed to have no speed

loss, while further back did cost a few knots.  This

is why I suggested a max of 6" back.  My worst loss in

max speed was about 5 knots on a further aft position.



The VG stalls were much more controlled in that I

could cross control or use considerable rudder and

still fly the plane in the stall without uncontrolled

fall off to a side.  That alone made the VG's a good

deal to me.  If you inadvertently stall it, nothing

real scarry happens and recovery is even easier than

usual for a KF.  It makes slow flight and short field

work much more secure.



Unfortunately I got no significant reduction in stall

speed from them.  I'll test again in the future with

some enhanced elevator authority and see if that

helps.



But I wouldn't let any worry about cruise speed loss

stop you.  You can test several positions and use the

one that works best without more than a knot

difference in max speed.



Now cleaning the wing.... that will be a little

harder.



Kurt S.



--- Fox5flyer <morid(at)northland.lib.mi.us> wrote:



......I'd like to do the VGs across the whole

 	  Quote: 	
		   wing, but I'm concerned about the loss of speed.

 That's about the only thing that's held me back.

 Deke


	


__________________________________________________

Fox5flyer
Guest

Posted: Sun Sep 10, 2006 3:54 am Post subject: Turtle deck vibration

Thanks for the feedback Dave.  Do you have a url for Harrison Designs?

Deke



---

Fox5flyer
Guest

Posted: Sun Sep 10, 2006 4:04 am Post subject: Turtle deck vibration

Thanks Kurt.  I definitely don't want to lose 5 kts, nor even 1 kt if I can

get away with it.  However, I can probably live with one kt if it has a good

enough trade off.  Lowering stall speed is always a good thing and making

the airplane more controllable close to stall is equally good.  Actually my

S5 is pretty good at low speeds, but it's always better if I can gain a

little more without the top end loss.  I know, there's almost always a trade

off somewhere.  One just has to decide what one can live with.

Deke

From: "kurt schrader" <smokey_bear_40220(at)yahoo.com>

 	  Quote: 	
		   Hi Deke,

 When I tested the VG's on my plane 2 years back, I

 found that the max speed varied a bit with position.

 Closer to the leading edge seemed to have no speed

 loss, while further back did cost a few knots.  This

 is why I suggested a max of 6" back.  My worst loss in

 max speed was about 5 knots on a further aft position.

 The VG stalls were much more controlled in that I

 could cross control or use considerable rudder and

 still fly the plane in the stall without uncontrolled

 fall off to a side.  That alone made the VG's a good

 deal to me.  If you inadvertently stall it, nothing

 real scarry happens and recovery is even easier than

 usual for a KF.  It makes slow flight and short field

 work much more secure.

 Unfortunately I got no significant reduction in stall

 speed from them.  I'll test again in the future with

 some enhanced elevator authority and see if that

 helps.

 But I wouldn't let any worry about cruise speed loss

 stop you.  You can test several positions and use the

 one that works best without more than a knot

 difference in max speed.

 Now cleaning the wing.... that will be a little

 harder.

 Kurt S.

 --- Fox5flyer <morid(at)northland.lib.mi.us> wrote:

 .......I'd like to do the VGs across the whole

 > wing, but I'm concerned about the loss of speed.

 > That's about the only thing that's held me back.

 > Deke

 __________________________________________________

dave(at)cfisher.com
Guest

Posted: Sun Sep 10, 2006 4:15 am Post subject: Turtle deck vibration

http://www.landshorter.com/

---

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