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04-18-2018, 12:54 PM
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Join Date: Oct 2005
Location: 08A
Posts: 9,500
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Slack means most tailwheels, if forced sideways, will pop into full swivel. You're allowing the tailwheel fork to swivel farther than the rudder.
Easy test...position your airplane with full rudder applied, rudder horn against the stops. Now push the tail sideways. If it is easy to push into full swivel, or is already released, the slack chains are allowing the fork to turn too far. We want a system which requires a brake tap to force into full swivel.
If tight chains (or a link) is causing the steering to be too quick, the arm ratio is wrong. Simply move the chains or link inboard on the rudder horn, or move them outboard on the fork arm. it will probably fix the aforementioned release angle problem too.
__________________
Dan Horton
RV-8 SS
Barrett IO-390
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04-18-2018, 01:26 PM
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Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 9,035
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Quote:
Originally Posted by DanH
Slack means most tailwheels, if forced sideways, will pop into full swivel. You're allowing the tailwheel fork to swivel farther than the rudder.
Easy test...position your airplane with full rudder applied, rudder horn against the stops. Now push the tail sideways. If it is easy to push into full swivel, or is already released, the slack chains are allowing the fork to turn too far. We want a system which requires a brake tap to force into full swivel.
If tight chains (or a link) is causing the steering to be too quick, the arm ratio is wrong. Simply move the chains or link inboard on the rudder horn, or move them outboard on the fork arm. it will probably fix the aforementioned release angle problem too.
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I agree with Dan but I believe that too tight can induce the same problem in (unintended unlock of the tail wheel) some cases.
When the airplane is traveling fwd with the tail wheel on the ground, it has a natural castor tendency to straighten out and align with the direction of travel. This will actually be countering any looseness in the chains and not allow the assembly to move far enough to unlock.
There have been instances where very tight chains are able to rotate the tail wheel far enough to unlock because the rudder is able to over come the natural castor force. This is particularly common with some installations of the single steering link because it doesn't cause an equal amount of tail wheel steering angle in both directions.
I know of one ground loop accident that I believe was cause because the tail wheel unlocked with full rudder input, with a steering link installed.
__________________
Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.
Scott McDaniels
Van's Aircraft Engineering Prototype Shop Manager
Hubbard, Oregon
RV-6A (aka "Junkyard Special ")
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04-18-2018, 01:30 PM
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Join Date: Jun 2007
Location: Atlanta
Posts: 745
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Quote:
Originally Posted by DanH
Slack means most tailwheels, if forced sideways, will pop into full swivel. You're allowing the tailwheel fork to swivel farther than the rudder.
Easy test...position your airplane with full rudder applied, rudder horn against the stops. Now push the tail sideways. If it is easy to push into full swivel, or is already released, the slack chains are allowing the fork to turn too far. We want a system which requires a brake tap to force into full swivel.
If tight chains (or a link) is causing the steering to be too quick, the arm ratio is wrong. Simply move the chains or link inboard on the rudder horn, or move them outboard on the fork arm. it will probably fix the aforementioned release angle problem too.
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Thanx Dan, I like your answer. I have a "lot" of slack in my chains, so your first answer is easy to do. Your 2ed answer, "if chains too tight", I wasn't a builder or mechanic, so I don't understand, but I "do" have a mechanic, and I'm sure he will understand.
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04-18-2018, 02:06 PM
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Join Date: Oct 2005
Location: 08A
Posts: 9,500
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Quote:
Originally Posted by rvbuilder2002
I agree with Dan but I believe that too tight can induce the same problem in (unintended unlock of the tail wheel) some cases.
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Agree...if the arm ratio is wrong.
It can't unlock if it doesn't reach the release angle.
__________________
Dan Horton
RV-8 SS
Barrett IO-390
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04-18-2018, 02:10 PM
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Senior Curmudgeon
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Join Date: Sep 2005
Location: Dayton Airpark, NV A34
Posts: 15,420
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Quote:
Originally Posted by DanH
It can't unlock if it doesn't reach the release angle.
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That is for a correctly installed, maintained and functioning unit. These things do require maintenance.
__________________
Mike Starkey
VAF 909
Rv-10, N210LM.
Flying as of 12/4/2010
Phase 1 done, 2/4/2011 
Sold after 240+ wonderful hours of flight.
"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."
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04-18-2018, 04:43 PM
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Join Date: May 2013
Location: Sherman, CT
Posts: 794
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I have always kept positive tension on all of my tailwheel springs, I think it reduces wear and allows for more precise control. I installed the Flyboys Rocket Link on my new -7 and I love it! My buddy put one on his -8 and he too is sold. Only 100 hrs since new, we'll see how it holds up.
__________________
Jake
RV6 #20477 completed 1991 sold.
RV7 #72018 N767T first flight 11/21/2017 350+ hrs.
IO-360M1B MT 3 blade, Dual AFS 5600 QUICK Panel.
Manual Flaps. (KOXC)Oxford, CT, (0NY0)North Creek, NY.
1941 J3 Cub skis,floats.
2020 dues gladly paid.
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04-18-2018, 08:16 PM
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Join Date: Jan 2005
Location: NC25
Posts: 3,508
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Quote:
Originally Posted by Ironflight
Tight chains vs slack in chains is a religious argument that I believe started between Wilbur and Orville.....I have great friends who are great (and we?ll respected)pilots on both sides of the argument. Both obviously work. Personally, I like tailwheel links, but I fly lots of planes with chains - loose and tight -and I just adapt.
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I have read all the posts in this thread. I agree that there will be a personal preference on how tight or how loose. Yes one gets use to different adjustments in different airplanes or at least Paul and I do.
I found that the chains furnished with the kit stretch and get loose after 300-hours. Taking out one links then makes it too tight for me. New chains work well till they get time on them and then stretch again.
I changed out the chain for cables on the standard "compression" springs and that was over 2,000 hours ago. Have flown other tailwheel airplanes and although not the exact way I like it on my airplane, there was no issue adapting to the difference.
__________________
Gary A. Sobek
NC25 RV-6 Flying
3,400+ hours
Where is N157GS
Building RV-8 S/N: 80012
To most people, the sky is the limit.
To those who love aviation, the sky is home.
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04-19-2018, 06:57 AM
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Join Date: Sep 2008
Location: Houston, Texas
Posts: 10
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After 25 yrs......
It's worth considering....(for tail wheel RV's) --- that little tail wheels are
sensitive to every little bump it runs into. Tight Springs/Cables makes
the rudder sensitive as well. Ever noticed some RV's who rudder wiggles
with every movements the tail wheels feels... almost rattling around all
the time. I've found over the years.... loose chains help with the overall
wear over the years. Iron Flight said it right..... it's easy to adjust.
Replacing a worn out rudder is a lot of work.
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04-19-2018, 01:59 PM
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Join Date: Jun 2005
Location: Hudson, WI
Posts: 244
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On both my RV-4 and RV-7 I have used Citabria tailwheel springs. I have the chain length set so they are "just" tight (or no slack). I do replace those cheap tailwheels every couple years as I think they steer funny when the rubber gets worn down flat. With this arrangement I feel the steering is positive but not twitchy. I don't care for slack in the chains which creates a "dead" spot in the steering.

__________________
Doug Weiler
Hudson, WI
president, Twin Cities RV Builders Group
RV-4, sold
RV-7 completed and flying N722DW, 840 hours
Based Lake Elmo, MN (21D)
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04-19-2018, 02:11 PM
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Join Date: Feb 2007
Location: colorado
Posts: 873
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Make too much of it..
Ive flown my rv4 with nothing connecting the tailwheel to the rudder several times..I like my chains loose so the rudder steers until about half deflection before the tailwheel gets pulled by the chains..
Cm
__________________
RV-4 "Mr. Twister"
Pitts S1S "Mexican Red" sold and missed
Mr. Twister Airshows
Rocky Mountain Renegades
the mission... have fun.
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