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S5 Trim and control forces

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skyring

Joined: 01 Nov 2006
Posts: 32

Posted: Sun Jul 03, 2011 2:10 am Post subject: S5 Trim and control forces

Our inspector is unhappy about the fact that in landing configuration i.e. 22 degree flaps and about 50 kts on our S5 Outback we still need some back pressure on the stick. That is, we can't trim out all of the nose down forces. My understanding is that this is normal on a Kitfox and there is no easy way (when fitted with the factory electric trim) to remove these forces. I can live with the very light back pressure required but he's clearly not happy. Is my assumption correct? Any comments appreciated. 

Kerry

S5 912ULS

Lynn Matteson

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

Posted: Sun Jul 03, 2011 2:29 am Post subject: S5 Trim and control forces

My test pilot and (later on) flight instructor had me add about  2"  

of length to the elevator trim on my IV. This helped, he said, but  

after I got my instruction in the plane and got used to it, I  found  

that 2" was too much and that it made the trim control too sensitive.  

I cut off about 1/4", then further fine-tuned the tab by increasing  

the length of the horn on the tab. This allowed the tab to move a  

shorter distance for each increment of the servo.



Lynn Matteson

Kitfox IV Speedster, taildragger

Jabiru 2200, #2062

Temporarily w/Sensenich 55.5 x 46 prop while

Prince prop (64 x 30, P-tip) is in for upgrade

Electroair direct-fire ignition system

Rotec TBI-40 injection (sleeved to 36mm)

Status: flying with "Ramcharger" intake manifold...1127 hrs (since  

3-27-2006)





On Jul 3, 2011, at 6:10 AM, skyring wrote:



 	  Quote: 	
		   

 <kerryskyring(at)hotmail.com>



 Our inspector is unhappy about the fact that in landing  

 configuration i.e. 22 degree flaps and about 50 kts on our S5  

 Outback we still need some back pressure on the stick. That is, we  

 can't trim out all of the nose down forces. My understanding is  

 that this is normal on a Kitfox and there is no easy way (when  

 fitted with the factory electric trim) to remove these forces. I  

 can live with the very light back pressure required but he's  

 clearly not happy. Is my assumption correct? Any comments appreciated.

 Kerry

 S5 912ULS





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=344765#344765

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

MichaelGibbs(at)cox.net
Guest

Posted: Sun Jul 03, 2011 10:34 am Post subject: S5 Trim and control forces

Certified airplanes are required to have enough trim authority to hold approach speed without pilot intervention but, of course, your Kitfox is not a certified airplane. And yes, this is normal for Kitfoxes.



Mike G.

Phoenix, AZ

Kitfox IV-1200 Speedster, Kitfox Series 6 (& 3/4!)

On Jul 3, 2011, at 3:10 AM, "skyring" <kerryskyring(at)hotmail.com> wrote:



 	  Quote: 	
		   

 

 Our inspector is unhappy about the fact that in landing configuration i.e. 22 degree flaps and about 50 kts on our S5 Outback we still need some back pressure on the stick. That is, we can't trim out all of the nose down forces. My understanding is that this is normal on a Kitfox and there is no easy way (when fitted with the factory electric trim) to remove these forces. I can live with the very light back pressure required but he's clearly not happy. Is my assumption correct? Any comments appreciated. 

 Kerry

 S5 912ULS

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=344765#344765

Tom Jones

Joined: 12 Mar 2006
Posts: 752
Location: Ellensburg, WA

Posted: Sun Jul 03, 2011 2:47 pm Post subject: Re: S5 Trim and control forces

Kerry, am I correct in assuming you are not located in the US?



The kitfox is a proven design.  A big and important part of the kitfox design is the flaperons which produce a nose down pitch when deployed as flaps.



Just throwing out some ideas.  Do you have authority as the manufacturer of this plane to write in the operators manual that normal landings are made with zero flaps, or maybe a placard on the panel to deal with it?



Your plane, with a 912 engine seems to be pretty much built by the book so I am also assuming its not a nose heavy condition that needs correcting?

_________________
Tom Jones
Classic IV
503 Rotax, 72 inch Two blade Warp
Ellensburg, WA

clint_bazzill(at)hotmail.
Guest

Posted: Sun Jul 03, 2011 3:44 pm Post subject: S5 Trim and control forces

Kerry,



I have a Model Iv-1200.  I had the same problem when the flaperons were employed.  I flew for almost 500 hours before playing with flaps.  I heard so many stories, all negative, I didn't go there.

Here is my solution, first I put springs on push pull tube to elevator.  That took the heavy weight off the elevator which will allow you to do more up trim.  Then I put gap seal in place.  Next I installed vortex generators under stabilizer.  Then I installed the larger elevator that is used on the nose wheel Model IV. 

I now slow the airplane in the pattern to 80 MPH indicated.  Apply the flaps, mostly full. Use full up trim.  The airplane flys at 65 to 70 with very little pressure on stick.  If you apply power, the nose will pitch up.  Hope this helps.

Clint 912ULS Model IV

 	  Quote: 	
		   

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=344819#344819

 

 

 

 

 

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skyring

Joined: 01 Nov 2006
Posts: 32

Posted: Sun Jul 03, 2011 10:01 pm Post subject: Re: S5 Trim and control forces

Thanks for all the replies and yes I am in Europe. The answers give me the reassurance I need that what we have is absolutely normal for a kitfox S5 with electric trim and the movable tail plane. 



Tom, yes we have built by the book and the inspector has indicated that a paragraph in the aircraft flight manual observing that in landing configuration with full flaps the aircraft will require some back-pressure on the stick could satisfy him. I would prefer this to one saying "no flaps" for landing as I think they are very useful at times. And a go-around with full flaps is also no problem with the S5. 



By the way the nose-down trim effect of the flaps was very useful when I had the trim stick in the full nose-up position (poor earth on switch) during testing. By using full flap and just enough power for 60 kts the control forces were quite manageable for a return to the field and problem free landing. So the plane meets the requirement for controls to overcome a runaway trim. 



Thanks again to the list. Kerry.

jdmcbean(at)kitfoxaircraf
Guest

Posted: Mon Jul 04, 2011 9:04 am Post subject: S5 Trim and control forces

Kerry,

	It is not uncommon... You should check the stabilizer rigging.  We

have a trim assist that helps significantly...

Fly Safe !!

John McBean

Ph 208.337.5111

www.kitfoxaircraft.com 

"The Sky is not the Limit...  It's a Playground" 



--

Dorsal

Joined: 29 Mar 2008
Posts: 34
Location: MA

Posted: Tue Jul 05, 2011 10:56 am Post subject: Re: S5 Trim and control forces

Go for the trim assist that John speaks of, works great.

_________________
Dorsal ~~^~~
Series 7 Flying
912S Warp Drive

kitfoxmark(at)gmail.com
Guest

Posted: Wed Jul 06, 2011 11:54 am Post subject: S5 Trim and control forces

I have about 500 hrs in my S5 with 912 and factory electric trim.  As

a rule, I don't use flaps when landing solo, and use only 1 notch when

landing with a passenger.  In both cases, I use the horizontal

stabilizer trim to relieve stick pressure.



If landing solo on short strips, I'll use 1 notch of flaps, use about

all the nose up trim I have, and also use stick-back pressure as

needed.



I've found using 2 notches of flaps either unnecessary or undesirable.

skyring

Joined: 01 Nov 2006
Posts: 32

Posted: Sun Jul 10, 2011 9:50 pm Post subject: Re: S5 Trim and control forces

John, of course, I had forgotten you had a system to take the trim forces out. I will be in touch about that and a couple of other things we need. All the best. Kerry

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