VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics


Go Back   VAF Forums > Model Specific > RV-9/9A
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 11-11-2015, 07:15 PM
RV-9 Yellow Bird RV-9 Yellow Bird is offline
 
Join Date: Aug 2015
Location: Wolcott, NY
Posts: 2
Default Best way to trim the rudder?

At cruise, my RV-9 flies hands off with the ball about half a diameter to the left, requiring left rudder to center it. I'd appreciate some guidance on how big of a wedge I need to glue on the rudder to correct it, and if somebody knows where I can get a plastic wedge kit rather than using a wood wedge.

Thanks,
Brian RV-9
Reply With Quote
  #2  
Old 11-11-2015, 08:14 PM
alpinelakespilot2000 alpinelakespilot2000 is offline
 
Join Date: Jan 2005
Posts: 3,353
Default

About 3/4 of one of these placed midpoint on the rudder addressed my trim needs when the ball was 1/2 out:
http://www.averytools.com/prodinfo.asp?number=9883. Hurry though b/c Avery is closing things up pretty quick.

I recently moved my wedge down to the bottom of the rudder where it is less obtrusive visually. However, since it is probably now partially blanketed by the HS and elevators, I find that I probably need a bit more of the wedge.

Long and short, decide where you want to locate yours and then just trim a little at a time until you find the right size to center the ball.

Good luck.
__________________
Steve M.
Ellensburg WA
RV-9 Flying, 0-320, Catto

Donation reminder: Jan. 2018
Reply With Quote
  #3  
Old 11-11-2015, 08:52 PM
shamer's Avatar
shamer shamer is offline
 
Join Date: Jul 2006
Location: Eagle, Id
Posts: 76
Default Rudder trim wedge mounting method

To mount the wedge for determining its size, use scotch 3M temporary double side poster tape, the thin clear stuff just like Scotch Tape. It is strong enough to secure the wedge while you figure out how big it must be and is easily removeable for adjustments. Use new tape each time. Once you have finalized the wedge size, switch to the permanent Scotch 3M tape. It sounds hokie but mine has been on there for over 8 years using this tape.
This tape is very thin so the wedge fits flush to the rudder. Cleanliness is important and the area must be free of wax.
__________________
Steve Hamer
RV-6
Eagle, ID
Reply With Quote
  #4  
Old 11-12-2015, 04:52 AM
Captain Avgas Captain Avgas is offline
 
Join Date: Oct 2005
Location: Melbourne, Australia
Posts: 1,575
Default

Quote:
Originally Posted by RV-9 Yellow Bird View Post
At cruise, my RV-9 flies hands off with the ball about half a diameter to the left, requiring left rudder to center it. I'd appreciate some guidance on how big of a wedge I need to glue on the rudder to correct it, and if somebody knows where I can get a plastic wedge kit rather than using a wood wedge.

Thanks,
Brian RV-9
Installing a trim tab on the rudder is treating the symptom rather than treating the cause of the problem. If the skid ball is out you obviously have a rigging problem that is causing asymmetrical drag and hence yaw. I recommend you start by taking a good look at your wheel and gear leg fairings to make sure they are in trail. It has been reported than an error of just 1/8" in the trailing edge of a gear leg fairing can cause a half scale deflection of the skid ball.
__________________
Regards
Bob Barrow
RV7A
Reply With Quote
  #5  
Old 11-12-2015, 05:29 AM
HFS HFS is offline
 
Join Date: Aug 2009
Location: Lemoore, CA
Posts: 199
Default Can You Say - Gurney Flap?

Look it up!

Gurney Flap - Wiki


HFS
Reply With Quote
  #6  
Old 11-12-2015, 08:56 AM
Rupester Rupester is offline
 
Join Date: Dec 2005
Location: Mahomet, Illinois
Posts: 2,134
Default

Another vote here for the Avery rudder wedge approach. Cheap, easy, and effective. . Mine ended up as noted above ... About 3/4 of the original wedge length located mid span.
__________________
Terry Ruprecht
RV-9A Tip-up; IO-320 D2A
S. James cowl/plenum
(Dues paid thru Nov '17)
Reply With Quote
  #7  
Old 11-12-2015, 09:02 AM
Bill Dicus Bill Dicus is offline
 
Join Date: Jan 2005
Location: Shorewood, WI (Milwaukee area)
Posts: 1,053
Default Gurney flap

Wow! Dan's a shirttail relation and I never knew he did that. Sounds worth a try on my left flap lower (?) surface to correct a 1/3 right ball in cruise. Has anyone on the site given this a try?
__________________
Bill Dicus
Shorewood (Milwaukee) Wisconsin
RV-8 N9669D Flying 12/4/14!
Flying Pitts S-2A, Piper Lance
Reply With Quote
  #8  
Old 11-12-2015, 09:46 AM
az_gila's Avatar
az_gila az_gila is offline
 
Join Date: Jan 2005
Location: 57AZ - NW Tucson area
Posts: 8,495
Smile

Quote:
Originally Posted by Bill Dicus View Post
Wow! Dan's a shirttail relation and I never knew he did that. Sounds worth a try on my left flap lower (?) surface to correct a 1/3 right ball in cruise. Has anyone on the site given this a try?
Small world, the person who named it married an engineer who worked for me...
__________________
Gil Alexander
EAA Technical Counselor, Airframe Mechanic
RV-6A N61GX - finally flying
Grumman Tiger N12GA - flying
La Cholla Airpark (57AZ) Tucson AZ
Reply With Quote
  #9  
Old 11-12-2015, 10:20 AM
Bill Dicus Bill Dicus is offline
 
Join Date: Jan 2005
Location: Shorewood, WI (Milwaukee area)
Posts: 1,053
Default Gurney flap

Thanks Gil - neat to hear. My maternal aunt was Dan's mother's sister. Got to meet him only once but he is memorable. His accomplishments as a driver, builder and innovator are amazing. Interesting - his dad was a baritone with the Metropolitan Opera, reputed to do limericks and great jokes non-stop for 48 hours; quite a raconteur! Sorry - this is really peripheral. Hope someone enjoys.
__________________
Bill Dicus
Shorewood (Milwaukee) Wisconsin
RV-8 N9669D Flying 12/4/14!
Flying Pitts S-2A, Piper Lance
Reply With Quote
  #10  
Old 11-12-2015, 05:28 PM
HFS HFS is offline
 
Join Date: Aug 2009
Location: Lemoore, CA
Posts: 199
Default Use of Gurney Flap

A -4 in Santa Paula (SZP) is using one now on his rudder - very effective, and not very big.

HFS
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 06:36 PM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.