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  #1  
Old 08-28-2011, 06:56 PM
woodsideraff woodsideraff is offline
 
Join Date: Aug 2007
Location: Aiken, SC
Posts: 124
Question Rudder Cable Link lengths, rigging

I am ready to mark and drill the rudder cable links. If I increase the cable tension enough, I end up with practically no length for the links.

I was pretty careful in building my wooden rigging fixture, using high quality 1/2" plywood instead of the crating wood. I'll check again the dimensions tomorrow when I return to the airport to build.

I'm wondering what is the link length that others end up with?

How much tension should be put on the cables for drilling?

Anybody with a good idea on clamping the rudder exactly on trail?

Also, it seems to me that, since the rudder pedal cable attach points are higher than the back bulkhead bushings, there will be quite a bit of rubbing on the top side of the bushings in the most forward bulkhead. How long before that cable eats through the bushing?

It's been my experience that whenever something doesn't fit perfectly, I've done something wrong. Hope this is the case again this time.

Cheers,

Rafael

RV8A bought and flying

RV12 500 hours into the build
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  #2  
Old 08-28-2011, 07:57 PM
Mich48041 Mich48041 is offline
 
Join Date: Apr 2008
Location: Riley TWP MI
Posts: 2,764
Default 32-12 Rudder links

See my hints:
http://www.vansairforce.com/communit...ad.php?t=70542
When completed, the center of the holes were exactly 2" apart on the left link and 1" apart on the right link.
The rudder cable lengths are not critical. When flying, your feet keep the cables tight. Otherwise the cables sag and touch the tail cone frames. Your feet will not be able to tell if a cable is a little bit too short or too long.
Quote:
How much tension should be put on the cables for drilling?
Not enough to bend anything. Just pull the cable tight by hand and mark.
Quote:
If I increase the cable tension enough, I end up with practically no length for the links.
Something is wrong.
Joe Gores
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  #3  
Old 08-28-2011, 09:05 PM
rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 7,999
Default

Quote:
Originally Posted by Mich48041 View Post
The rudder cable lengths are not critical. When flying, your feet keep the cables tight.
Not entirely true.

If the links are too long the rudder pedals will be bumping the firewall when the rudder hits the travel stops. If the links are excessively long, you will never get full rudder travel before the rudder pedals get stopped by the firewall.
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  #4  
Old 01-18-2019, 01:34 PM
cook_ts cook_ts is offline
 
Join Date: Nov 2008
Location: Chino, CA
Posts: 10
Default Rudder pedal rigging and cable lengths

1- I have my pedal assy located per plans (even though I drilled for two more positions). Also noting that if this position changes, so will the cable length.

2- I used a length of 1" angle zip tied around the lower petal beams to keep all aligned. In doing so, this also 'locks' the forward/aft movement/position of the pedals- Note- This is the ONLY way to get 'tension' in the cables. Without restraining all pedals, there will be no tension.

3- I use a length of 6-32 threaded rod and fender washers slipped through the counterbalance gap at the top of the rudder/vertical to hold the rudder at neutral (and also the elevators/horizontal).

4- In doing all this, my lengths are longer than expected- 3.1" & 3.5" hole to hole.

5- As mentioned, the actual lengths are not that critical, but need to make sure the rudder pedals don’t hit the firewall at full travel. I am only repeating this because you also need to consider include brake petals as well.

6- Going back to point 4, although I am happy with the rigging, one issue I had given the length of the links, the swedged end of the cable actually snags on the first guide hole. Still working a solution for this.
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  #5  
Old 01-18-2019, 05:17 PM
bobg56 bobg56 is offline
 
Join Date: Nov 2018
Location: Peachtree City, GA
Posts: 43
Default

I bought my RV12 so I didn't build it, mine has a pretty large wedge attached to the LH side of the rudder as a tab...I'm not sure that when the holes were drilled the rudder was neutral... I don't understand why cable turn barrels are nut used in the rudder system like they are in the horz. stab. this way you could rig the rudder to a closer tolerance than by drilling holes...also the cables when slack rest on one of the fuselage formers, I applied a few layers of aluminum tape to keep them from getting worn.
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  #6  
Old 01-18-2019, 06:36 PM
rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 7,999
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Quote:
Originally Posted by cook_ts View Post
1- I have my pedal assy located per plans (even though I drilled for two more positions). Also noting that if this position changes, so will the cable length.

2- I used a length of 1" angle zip tied around the lower petal beams to keep all aligned. In doing so, this also 'locks' the forward/aft movement/position of the pedals- Note- This is the ONLY way to get 'tension' in the cables. Without restraining all pedals, there will be no tension.

3- I use a length of 6-32 threaded rod and fender washers slipped through the counterbalance gap at the top of the rudder/vertical to hold the rudder at neutral (and also the elevators/horizontal).

4- In doing all this, my lengths are longer than expected- 3.1" & 3.5" hole to hole.

5- As mentioned, the actual lengths are not that critical, but need to make sure the rudder pedals don’t hit the firewall at full travel. I am only repeating this because you also need to consider include brake petals as well.

6- Going back to point 4, although I am happy with the rigging, one issue I had given the length of the links, the swedged end of the cable actually snags on the first guide hole. Still working a solution for this.
Are you building an RV-12? That is what this conversation was about ( the 12 is a little bit different from the others.
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Hubbard, Oregon
RV-6A (aka "Junkyard Special ")
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  #7  
Old 01-18-2019, 10:13 PM
Mich48041 Mich48041 is offline
 
Join Date: Apr 2008
Location: Riley TWP MI
Posts: 2,764
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The holes in rudder cable links could be a half inch off and it would not have any affect on rudder trim. The length of the rudder cables does not affect rudder trim.
Quote:
I don't understand why cable turn barrels are not used in the rudder system like they are in the horz. stab. this way you could rig the rudder to a closer tolerance than by drilling holes.
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RV-12 Flying
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  #8  
Old 01-19-2019, 08:08 PM
bobg56 bobg56 is offline
 
Join Date: Nov 2018
Location: Peachtree City, GA
Posts: 43
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I believe what your saying but it doesn't make sense to me, most of all my GA experience is Cessna and Piper.
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  #9  
Old 01-19-2019, 08:49 PM
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Piper J3 Piper J3 is offline
 
Join Date: Nov 2014
Location: Hinckley, Ohio
Posts: 1,258
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When you fly the plane and determine that rudder trim is necessary to center-the-ball you will add the triangular metal tab to the trailing edge of the rudder. This will aerodynamically bias the rudder and eliminate the need to hold rudder pressure with your feet – thus it doesn’t matter if the rudder cables are not equal length. The rudder trim tab should be bent at an angle to allow the airplane to fly straight (no skid or slip) in cruise flight. You will still need to hold a significant amount of right rudder in a climb to overcome engine torque and P-factor.
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  #10  
Old 01-19-2019, 09:01 PM
RFSchaller RFSchaller is offline
 
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Location: Phoenix, AZ
Posts: 2,411
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Or just rivet on a conventional trim tab after certification like I did. I also put them on the flaperons. Old school, but makes adjustments easy.
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