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09-23-2018, 12:10 PM
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Join Date: Sep 2007
Location: Southeastern, MN
Posts: 18
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Directional Control on Rollout
After seeing that another RV-8 ran off a runway last week I thought I’d share my experience with my own directional control on rollout issues.
I finished my RV-8 in 2014. It had a Bell tailwheel fork and a single steering arm on it. It looked dandy! I liked the way it handled while taxiing and I was happy. It wasn’t very long after my first flight that I noticed controllability during the landing rollout was not as good as I would have liked. I never left the runway or scratched anything but came way too close on more than one occasion. Sometimes the rollout was straight as an arrow, but the excitement started as soon as the SLIGHTEST correction was made to chance direction. Wind speed or direction did not matter. My RV grin turned to an RV grimace right before touchdown.
I talked to local experts and any RV guys I found at OSH, phoned distant experts and poured through VAF archives. I checked toe in/out several times and it was fine. I was SURE I must be dragging a brake since sometimes it would be turning opposite the rudder input. Usually turning right while applying full left rudder AND brake. I found Randy Leverold’s rudder pedal extension plans and modified my pedals. Initially I thought I had the problem solved but it was only about a dozen landings or so before the same symptoms popped up.
My attention turned to the tailwheel again. I propped the tail up on a saw horse, checked the adjustment again, checked the locking pin operation again and checked for freedom of movement again. I went back to VAF and read about what a docile pussy cat the RV-8 was to land. I could 3 point or wheel land on either or both mains with no problem, but just couldn’t seem to keep it going straight. Either my issue was unique, or everyone just figures it’s a problem with the pilot and they’re embarrassed to say anything. While the thought of selling it and buying a 150 flashed through my head, I got the idea to lift the tail by the bottom of the wheel. I interlaced my fingers and lifted the tailwheel while turning it left and right at the same time. The more weight I put on it, the harder it was to turn. By the time I had the tail totally lifted up I could barely turn it. Light bulb time! I greased it up really good and flew it again. It was magnificent! But in only 5 to 10 landings it started to get stiff again. I looked back and found there were 30 landings on the grease job prior to discovering the binding. I disassembled the tailwheel assembly and looked for burrs, or anything amiss and found nothing. I put a grease zerk in the tailwheel yoke and polished everything in there really well. I’d give it a little pump of grease every other time I went flying and flew it until the next winter.
My fix was to buy a tailwheel yoke with the ball bearing from JDair, keep my Bell fork, install the stock springs and make custom steering cables attached to new attach points on the rudder (copied from Dan Horton). Another thing I learned was that full rudder deflection should not unlock the tailwheel. I couldn’t achieve that without machining out a little of the key slot in the top of the yoke if I kept my single steering arm.
With 10,000 RVs flying and a bunch of them tail draggers I don’t think there’s anything wrong with the Van’s yoke, but the combination of MY stock yoke, and MY Bell fork and (maybe) MY steering link did not allow ME to steer.
I have been flying with this tailwheel set up for almost two years and it has transformed my tasmanian devil into the pussy cat I read about.
The lack of complaints about this prompted me to write about my experience. Maybe it’s unique, maybe not, but if it saves just one RV I’ll be happy.
I am curious if this has caused any loss of control accidents? You’ll never know unless you lift and turn.
__________________
RV-8 Built and Flying
Last edited by NLPete : 02-16-2020 at 10:02 AM.
Reason: tried updating picture
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09-23-2018, 12:20 PM
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Join Date: Mar 2008
Location: Huntsville, AL USA
Posts: 546
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I too have a Bell fork on my RV-7 but have the Tail-Lynx cable and spring set up. Never had the roll out directional problem you describe - but I can definitely tell when it is time to lube the fork! Mine gets difficult to steer when taxing - rudder pedal pressure just stretches the springs on the Tail-Lynx. When the wheel does move, it moves suddenly. I have described it as "notchy" steering. Cleaning and re-lubing the fork shaft fixes it for another bunch of hours.
__________________
Dan Langhout
2020 =VAF= Dues PAID . . . . .
RV-7 N528DP slow build
First Flight July 26th, 2014
665 hours and counting . . . .
Now based at Moontown (3M5)
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09-23-2018, 12:48 PM
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Join Date: Jun 2007
Location: Atlanta
Posts: 745
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Rocket single arm steering
Quote:
Originally Posted by NLPete
After seeing that another RV-8 ran off a runway last week I thought I?d share my experience with my own directional control on rollout issues.
I finished my RV-8 in 2014. It had a Bell tailwheel fork and a single steering arm on it. It looked dandy! I liked the way it handled while taxiing and I was happy. It wasn?t very long after my first flight that I noticed controllability during the landing rollout was not as good as I would have liked. I never left the runway or scratched anything but came way too close on more than one occasion. Sometimes the rollout was straight as an arrow, but the excitement started as soon as the SLIGHTEST correction was made to chance direction. Wind speed or direction did not matter. My RV grin turned to an RV grimace right before touchdown.
I talked to local experts and any RV guys I found at OSH, phoned distant experts and poured through VAF archives. I checked toe in/out several times and it was fine. I was SURE I must be dragging a brake since sometimes it would be turning opposite the rudder input. Usually turning right while applying full left rudder AND brake. I found Randy Leverold?s rudder pedal extension plans and modified my pedals. Initially I thought I had the problem solved but it was only about a dozen landings or so before the same symptoms popped up.
My attention turned to the tailwheel again. I propped the tail up on a saw horse, checked the adjustment again, checked the locking pin operation again and checked for freedom of movement again. I went back to VAF and read about what a docile pussy cat the RV-8 was to land. I could 3 point or wheel land on either or both mains with no problem, but just couldn?t seem to keep it going straight. Either my issue was unique, or everyone just figures it?s a problem with the pilot and they?re embarrassed to say anything. While the thought of selling it and buying a 150 flashed through my head, I got the idea to lift the tail by the bottom of the wheel. I interlaced my fingers and lifted the tailwheel while turning it left and right at the same time. The more weight I put on it, the harder it was to turn. By the time I had the tail totally lifted up I could barely turn it. Light bulb time! I greased it up really good and flew it again. It was magnificent! But in only 5 to 10 landings it started to get stiff again. I looked back and found there were 30 landings on the grease job prior to discovering the binding. I disassembled the tailwheel assembly and looked for burrs, or anything amiss and found nothing. I put a grease zerk in the tailwheel yoke and polished everything in there really well. I?d give it a little pump of grease every other time I went flying and flew it until the next winter.
My fix was to buy a tailwheel yoke with the ball bearing from JDair, keep my Bell fork, install the stock springs and make custom steering cables attached to new attach points on the rudder (copied from Dan Horton). Another thing I learned was that full rudder deflection should not unlock the tailwheel. I couldn?t achieve that without machining out a little of the key slot in the top of the yoke if I kept my single steering arm.
http://i67.tinypic.com/2s94zz7.jpg
With 10,000 RVs flying and a bunch of them tail draggers I don?t think there?s anything wrong with the Van?s yoke, but the combination of MY stock yoke, and MY Bell fork and (maybe) MY steering link did not allow ME to steer.
I have been flying with this tailwheel set up for almost two years and it has transformed my tasmanian devil into the pussy cat I read about.
The lack of complaints about this prompted me to write about my experience. Maybe it?s unique, maybe not, but if it saves just one RV I?ll be happy.
I am curious if this has caused any loss of control accidents? You?ll never know unless you lift and turn.
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I had a (I think it was a Rocket" single arm) on my 1st RV 8. Almost every time I landed it, (wheel landings), and the tail came down, I thought for sure I was going off the runway into the grass.  It was "really" bad with a guy in the back seat. 
Now on my 2ed RV 8, I've got the double chain throw. No problems whatsoever. I'd switch if I were you. 
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09-23-2018, 12:54 PM
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Join Date: Sep 2008
Location: Fayetteville, Georgia
Posts: 215
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I tried many different greases on my tailwheel? most all were very short term fixes. Finally tried Lubriplate 630 AA grease. Lasts MUCH longer than anything else I?ve tried. Now I relube it every other oil change and it never gets sticky. Your results may vary!
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09-23-2018, 12:55 PM
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Join Date: Nov 2015
Location: Nikiski, AK
Posts: 413
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Similar RV-6 Learning Experience
When I bought my RV-6, had similar issues. Thought it was just me having issues learning to fly a tail wheel.
Decided to ask some questions here. Learned real fast I needed to look at the operation.
Lifted the tail, used a jack stand, and pulled apart the steering assembly. The grease had turned into a "glue" locking the worn out spring, allowing only "full castering" operation.
Before my own investigation, with help from here, each time I asked a non-homebuilt savy AP, they just greased it again.
Bought new plunger and spring, cleaned up all the gook from the grease. Now I use a special dry lube for bicycle chains. Re-lube every three months.
Works like a charm, all the experience from the full castering landings taught me to be quick on the rudders.
Now directional control for landings is no longer a question of, "which way is it going to go?"
Glad you found your issue, thank you for sharing your experience.
Best regards,
Mike Bauer
__________________
Mike Bauer
N999SN 1998 Syd Nelson RV-6 (purchased 2017)
UTC -09:00 Alaska
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02-19-2020, 06:46 AM
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Join Date: Dec 2011
Location: Roanoke, Va
Posts: 36
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thank you bubba
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02-19-2020, 06:49 AM
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Join Date: Dec 2011
Location: Roanoke, Va
Posts: 36
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Thank you to all
Thank you, I will study bubba
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02-19-2020, 07:22 AM
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Join Date: May 2014
Location: KBVY Massachusetts
Posts: 1,100
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I used to get those swerves - tower must have had a great time when they saw me come in. I have the solid steering arm. I found a solution that works for me:
Firstly, I always wheel it on - tail slightly low. So my solution won't work for the 3 pointers.
Then I keep the tail up on rollout...always moving the stick forward as the tail starts to come down.
Finally, the tail eases itself down slowly as the speed gets really low. Tailwheel touches nice and gently. By that time the plane is going so slowly that it's easy to control. There's no massive lunge for the weeds.
__________________
Flying RV-8 N880BC
2019 Dues - happily paid.
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02-19-2020, 07:57 AM
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Join Date: Sep 2015
Location: Socal
Posts: 453
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As you said, many people have different experiences. I have the stock Van's tail wheel with about 1 inch of slack in the chains (per the plans) and have been very happy with the control ability. I think the slack helps with controlability at landing speeds.
__________________
RV-8 N695RA flying
Working on an RV-4
Born to fly, forced to work
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02-19-2020, 08:17 AM
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Join Date: Sep 2007
Location: Hudson County, NJ
Posts: 1,092
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I got my RV-7 back from annual a little over a year ago and it was really hard to control on the ground. I knew nothing was binding but it was very difficult to initiate a taxi turn. So I also knew I had to pull the system apart and see what was happening. As soon as I touched the pivot area, I knew what was wrong. The mechanic had 'serviced" it and used some type of very tacky substance. It wasn't grease per se, it was very sticky to the touch, like fuel lube. So I pulled the system apart, cleaned all the "lube" out, and greased it with my chosen white lithium grease. Smooth as butter.
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