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Trim for level flight

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recapen(at)earthlink.net
Guest

Posted: Mon Sep 07, 2009 3:57 am Post subject: Trim for level flight

Folks,

  

 I'm at just under 31 hours in my flight testing and  have been getting things set up for hands-off and autopilot flying.  I got  the hands off part finished and found that I need a little up-trim to mainatain  altitude - the left/right part is fine with zeroe'd roll trim and will allow for  some fuel difference in the tanks before it tries to roll in any  direction.  Similarly,  when I'm running the autopilot, it'll fly  straight and level forever - so I zeroe'd out the elevator trim and turned off  the autopilot - and got the expected descent - until I added back the  up-trim.

  

 Leads me to think that my Horizontal Stabilizer  needs to have its angle of attack lowered a little bit.

  

 My CG is in the forward part of the range but not  waay forward.  I'm going to try it with the CG a little farther aft and see  what happens.  The airframe is still 'dirty' as I haven't added leg  fairings or covered the mainwheels - the nosewheel is covered per Vans  requirements.

  

 It will trim for a climb or descent as desired -  but will always descend if I zero out the elevator trim.

  

 What do you folks think?

  

 Meanwhile, what a wonderful machine!

  

 Thanks,

 Ralph

 N822AR (at) N06 - just under 31  hours

   [quote][b]

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pitts_pilot(at)bellsouth.
Guest

Posted: Mon Sep 07, 2009 4:38 am Post subject: Trim for level flight

Before you spend the time changing the incidence in the tail, I'd make 

sure that it's really out ..... and not a CG thing.  Do your test at 

varying airspeeds to see if you need to tweak the tail.  My Traumahawk 

will trim lock to lock from low speed to high .... so I know it's out of 

whack.

Linn



Ralph E. Capen wrote:

 	  Quote: 	
		   Folks,

  

 I'm at just under 31 hours in my flight testing and have been getting 

 things set up for hands-off and autopilot flying.  I got the hands off 

 part finished and found that I need a little up-trim to mainatain 

 altitude - the left/right part is fine with zeroe'd roll trim and will 

 allow for some fuel difference in the tanks before it tries to roll in 

 any direction.  Similarly,  when I'm running the autopilot, it'll fly 

 straight and level forever - so I zeroe'd out the elevator trim and 

 turned off the autopilot - and got the expected descent - until I added 

 back the up-trim.

  

 Leads me to think that my Horizontal Stabilizer needs to have its angle 

 of attack lowered a little bit.

  

 My CG is in the forward part of the range but not waay forward.  I'm 

 going to try it with the CG a little farther aft and see what happens.  

 The airframe is still 'dirty' as I haven't added leg fairings or covered 

 the mainwheels - the nosewheel is covered per Vans requirements.

  

 It will trim for a climb or descent as desired - but will always descend 

 if I zero out the elevator trim.

  

 What do you folks think?

  

 Meanwhile, what a wonderful machine!

  

 Thanks,

 Ralph

 N822AR (at) N06 - just under 31 hours

 

 *

 

 

 *

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recapen(at)earthlink.net
Guest

Posted: Mon Sep 07, 2009 4:53 am Post subject: Trim for level flight

Good point - I'll try it at different airspeeds and valid CG configurations 

before I monkey with it......



---

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khorton01(at)rogers.com
Guest

Posted: Mon Sep 07, 2009 7:10 am Post subject: Trim for level flight

On 2009-09-07, at 7:56 AM, "Ralph E. Capen" <recapen(at)earthlink.net (recapen(at)earthlink.net)> wrote:



 	  Quote: 	
		    Folks,

  

 I'm at just under 31 hours in my flight testing and  have been getting things set up for hands-off and autopilot flying.  I got  the hands off part finished and found that I need a little up-trim to mainatain  altitude - the left/right part is fine with zeroe'd roll trim and will allow for  some fuel difference in the tanks before it tries to roll in any  direction.  Similarly,  when I'm running the autopilot, it'll fly  straight and level forever - so I zeroe'd out the elevator trim and turned off  the autopilot - and got the expected descent - until I added back the  up-trim.

  

 Leads me to think that my Horizontal Stabilizer  needs to have its angle of attack lowered a little bit.

  

 My CG is in the forward part of the range but not  waay forward.  I'm going to try it with the CG a little farther aft and see  what happens.  The airframe is still 'dirty' as I haven't added leg  fairings or covered the mainwheels - the nosewheel is covered per Vans  requirements.

  

 It will trim for a climb or descent as desired -  but will always descend if I zero out the elevator trim.

  

 	  Quote: 	
		  	


	


I wouldn't worry about this until you have all the fairings on. The aircraft will be faster, and you need to trim more nose down as the speed increases. 

Kevin Horton

 [quote][b]

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mcculleyja(at)starpower.n
Guest

Posted: Mon Sep 07, 2009 8:12 am Post subject: Trim for level flight

When you eventually add gear and wheel fairings you will see much less 

up-trim needed due to less drag from the current pitch-down drag of 

gear. May even reverse the trim needed.



Jim McCulley

====================================================================================



Ralph E. Capen wrote:

 	  Quote: 	
		   Folks,

  

 I'm at just under 31 hours in my flight testing and have been getting 

 things set up for hands-off and autopilot flying.  I got the hands off 

 part finished and found that I need a little up-trim to mainatain 

 altitude - the left/right part is fine with zeroe'd roll trim and will 

 allow for some fuel difference in the tanks before it tries to roll in 

 any direction.  Similarly,  when I'm running the autopilot, it'll fly 

 straight and level forever - so I zeroe'd out the elevator trim and 

 turned off the autopilot - and got the expected descent - until I added 

 back the up-trim.

  

 Leads me to think that my Horizontal Stabilizer needs to have its angle 

 of attack lowered a little bit.

  

 My CG is in the forward part of the range but not waay forward.  I'm 

 going to try it with the CG a little farther aft and see what happens.  

 The airframe is still 'dirty' as I haven't added leg fairings or covered 

 the mainwheels - the nosewheel is covered per Vans requirements.

  

 It will trim for a climb or descent as desired - but will always descend 

 if I zero out the elevator trim.

  

 What do you folks think?

  

 Meanwhile, what a wonderful machine!

  

 Thanks,

 Ralph

 N822AR (at) N06 - just under 31 hours

 

 *

 

 

 *

- The Matronics RV-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?RV-List

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