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Swiveling tail wheel

hcccs

hcccs

Well Known Member
I have assembled the tail wheel and was trying to see how the swiveling function worked. I pressed sideways on the wheel fork but nothing happened. The steering arm should press the sliding key into the recess of the arm whereby allowing the wheel to swivel freely. Should I chamfer the edges of the recess (arrows) ?


By hcccs
 
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hcccs said:
I have assembled the tail wheel and was trying to see how the swiveling function worked. I pressed sideways on the wheel fork but nothing happened. The steering arm should press the sliding key into the recess of the arm whereby allowing the wheel to swivel freely. Should I chamfer the edges of the recess (arrows) ?


By hcccs
Click to expand...

You shouldn't have to. It looks like it will work fine in practice. Full rudder deflection will disengage it with a gentle cam action. That feature of the mechanism is on top of the bushing and is covered up by the horn plate in the picture.
Jim Sharkey
RV6 - Phase 1
 
The unlock feature has NOTHING to do with the amount of pressure applied. It is only concerned with the angle of displacement of the fork. Take the steering horn off (so you can see the cam and pin working), and rotate the fork to the side. The operation will become immediately obvious. Also, this will give you some good insight on how this excellent tailwheel can bite you if treated wrong (such as touching down with full deflection of the rudder).
 
A little may be good...

but too much and you have a full swivel wheel. It only took one more pass with the die grinder and hard to move became too easy. If you decide to do this a little at time is prudent. I left it the way it is. I figured I'd only get better at the foot-rudder thing. It seems to be working. I now have happy feet.:rolleyes: Tailwheels a soo cool.
 
I wouldn't try modifying that part if I were you.

I believe it is really only supposed to be a convenience thing so that you can more easily push your plane back into the hangar. With that tailwheel bracket, you can push your plane backward and when the wheel casters backwards, it will unlock from the control cables and allow you to push it backward without it trying to steer for you.

Hopefully that makes sense.

If you take the top plate off like jsharkey suggests, you should see how it functions.
 
Thanks for your replies. I'll leave it as it is until I see how it works in practice.
 
eurof2 said:
I believe it is really only supposed to be a convenience thing so that you can more easily push your plane back into the hangar. With that tailwheel bracket, you can push your plane backward and when the wheel casters backwards, it will unlock from the control cables and allow you to push it backward without it trying to steer for you.
Click to expand...

There are actually quite a few times when you want it to break out when taxiing - like when you want to swing the plane around in a short space on the ramp, or for run-up. It's not just for pushing it around in the hangar (although you are right - it is quite essential for that!).

Paul
 
hcccs said:
Thanks for your replies. I'll leave it as it is until I see how it works in practice.
Click to expand...

The steering horn is only used ONLY for steering- the unlock feature is found in the body of the unit. The fit between the pin and the horn is one of the main wear areas of this tailwheel, so modification of the steering horn with a grinder will only make the steering sloppy and drive you to replacement that much sooner. Again, just slip the steering horn off, and spin the wheel fork through 360 degrees to see how the pin cams out of the way at a certain angle off center. It will become obvious how it works.
 
After having mine break free two weeks ago in a stiff crosswind landing, I'm not sure that I want the free-swivel capability any longer...that event cost me a nice pair of underwear!
 
tinman said:
After having mine break free two weeks ago in a stiff crosswind landing, I'm not sure that I want the free-swivel capability any longer...that event cost me a nice pair of underwear!
Click to expand...

Did you happen to touch down at or near full rudder deflection (with the wheel off the ground)? If so, that's a ground loop in the making. In theory, this tailwheel should never unlock on the ground unless the ground track drives the fork off center enough to unlock (like locking a brake for a point turn, or pushing the airplane by hand). However, once the pin is "cammed out" by the angle of the fork, it's gone. This is one of the few operational weak links of the tailwheel - fortunately the conditions required to get the fork that far off center are pretty rare at anything faster than normal taxi speeds.
 
not so for me...

Mine unlocks all the time. This is particularly annoying in the run up area after a turn to line up. Now I have to wiggle the plane around to get the wheel to re-engage. It's also annoying if you get a sharp turn to line up on the active. The worst part is a sharp turn coming out of the hangar (necessary). Then I have to steer with the brakes until I get it lined back up.

It works as advertised. But after having a non-swivel TW originally, I regret having "upgraded" it.

John
 
You nailed it, Michael.
I got slow in my -8 and tried to convert a wheelie into a 3-point. I had a stiff wind sock at 90 degrees...the tailwheel went free-swivel on me and I was too slow for the rudder to have enough force to keep me straight. The rear end was already starting to get out of line, so it was too late for a brake correction. I had two options- hit the weeds, or hit the air. I dropped the hammer and crow-hopped in ground effect long enough to realign and set back down again. The whole event took less than 10 seconds, but my knees were shaking when I climbed out after shutdown...
 
John_RV4 said:
Mine unlocks all the time. This is particularly annoying in the run up area after a turn to line up. Now I have to wiggle the plane around to get the wheel to re-engage. It's also annoying if you get a sharp turn to line up on the active. The worst part is a sharp turn coming out of the hangar (necessary). Then I have to steer with the brakes until I get it lined back up.
Click to expand...

John,

If it unlocks that easily, it might very well be that the U-shaped slot in the control arm is wearing out. You may be able to get a little more life out of it by turning it over - but I'd put a new one on order as well. The control arm is a consumable item if you put lots of hours on the airplane.

Paul
 
John_RV4 said:
Mine unlocks all the time. This is particularly annoying in the run up area after a turn to line up. Now I have to wiggle the plane around to get the wheel to re-engage. It's also annoying if you get a sharp turn to line up on the active. The worst part is a sharp turn coming out of the hangar (necessary). Then I have to steer with the brakes until I get it lined back up.
Click to expand...

This is nomal. The rudder and tailwheel have to be perfectly aligned to lock back in after you have "asked" it to unlock because of a sharp turn - but once coupled, should "never" come apart unless you have reached the appropriate deflection angle with the fork (not rudder).

If you are unlocking at or near center or before driving the fork to the unlock angle, you have a worn out steering yoke (or someone has modified it with a grinder).
 
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tinman said:
You nailed it, Michael...
Click to expand...

Well, unfortunately it took a groundloop of epic proportions to finally figure out what the one major limitation of this tailwheel design is. I landed with a quartering tailwind one day, and a last second gust caught the tail just as it was about to touch down. I stabbed full rudder to correct, but at the same moment it went full travel and the pin "cammed out" of position, the wheel touched down and was gone.

Moral of the story: never, ever be at full deflection at touchdown if you want the tailwheel to do any steering after that.
 
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Sticky pin

Ironflight said:
If it unlocks that easily, it might very well be that the U-shaped slot in the control arm is wearing out. You may be able to get a little more life out of it by turning it over - but I'd put a new one on order as well. The control arm is a consumable item if you put lots of hours on the airplane. Paul
Click to expand...

Another thing that can cause the symptom is lubrication. I never use grease on the "pin", just some motor oil is fine. The grease will cause the pin to stick after it gets a little gummy and dirty.


John Clark
RV8 N18U "Sunshine"
KSBA
 
it is working fine....

Like I said, it's working fine. Been like that from day one. The pin is fine. That's how it's always worked. I just don't like it. I have the chains somewhat loose to insure the TW can be straight even with some rudder deflection.

Of course, having said all that, I better go and take it apart again and make sure :). Sorry for the thread creep.

John
 
Toobuilder said:
Well, unfortunately it took a groundloop of epic proportions to finally figure out what the one major limitation of this tailwheel design is. I landed with a quatering tailwind one day, and a last second gust caught the tail just as it was about to touch down. I stabbed full rudder to correct, but at the same moment it went full travel and the pin "cammed out" of position, the wheel touched down and was gone.

Moral of the story: never, ever be at full deflection at touchdown if you want the tailwheel to do any steering after that.
Click to expand...

Just for clarification, your episode was not in an RV, correct? (just looking at your signature). I've been flying my RV-6 for ten years and even though the two of us have experienced some pretty rambunctious crosswinds, there have never been any anxious moments due to the tailwheel unlocking during touchdown.

The RV is a quite stable and well-behaved taildragger, and it has been my experience that rudder alone is sufficient to keep the nose pointed straight until the tailwheel takes over. I'm not saying an unlocked tailwheel could never be an issue, but the tailwheel design isn't generally considered to be deficient in the RV traildragger community at large.
 
Sam Buchanan said:
Just for clarification, your episode was not in an RV, correct? (just looking at your signature)...
Click to expand...

Correct. It was in the Hiperbipe, but they share the same tailwheel design. My interest in this thread is to ensure everyone who reads it understands exactly what their tailwheel is doing. My ignorance of the specific operational traits of this tailwheel contributed to my groundloop, and I hope to save others from the same fate. Yes, the RV is a whole lot more tame on the ground than the Hiperbipe, but I'll bet a completely unlocked tailwheel would still be pretty sporty with an RV even under ideal conditions. It's a great tailwheel, but awareness of it's "limitations" makes it even greater.
 
John Clark said:
Another thing that can cause the symptom is lubrication. I never use grease on the "pin", just some motor oil is fine. The grease will cause the pin to stick after it gets a little gummy and dirty.


John Clark
RV8 N18U "Sunshine"
KSBA
Click to expand...
John,

You bring up a good point. I drilled a #30 hole in the stearing arm so I can put a drop or two of oil in there every so often without taking it apart.

Also, at one point my pin developed a small burr and didn't return after it was retracted. I flew like this way for 20 or 30 hours and didn't see a problem with having a full swiveling tail wheel. The only reason I fixed it was so that it would lock the rudder in place when parked on the ramp while traveling.
 
Toobuilder said:
Correct. It was in the Hiperbipe, but they share the same tailwheel design. My interest in this thread is to ensure everyone who reads it understands exactly what their tailwheel is doing. My ignorance of the specific operational traits of this tailwheel contributed to my groundloop, and I hope to save others from the same fate. Yes, the RV is a whole lot more tame on the ground than the Hiperbipe, but I'll bet a completely unlocked tailwheel would still be pretty sporty with an RV even under ideal conditions. It's a great tailwheel, but awareness of it's "limitations" makes it even greater.
Click to expand...

No, it really is a non-event. I have a steering link on my RV-6 instead of chains and twice over ten years I've had the link fail away from home. Both times I removed the link and flew the plane home and landed with the tailwheel free swiveling. Once was with a moderate crosswind, the other with little wind. The main difference with the full swiveling tailwheel was a "looser" feel while taxiing. The landings were normal and completely stress-free, sorry, no dramatic tales to tell. :)

It kinda made me wonder why we even fool with a "linked" tailwheel. But I guess the link is easier on the brakes and keeps the rudder from flopping in the breeze on the ramp.
 
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Sam,

It's good to know that RV's are so benign on the ground, but I still think it's important that people know how their machines work so that the response to input matches their expectations. Reading some responses to this and other threads leads me to believe that some people have only the most basic understanding of how their tailwheel works, and I'd just like to do my part to change that, that's all.
 
I have an instruction sheet that I provide with our Screaming Eagle tailwheels. It is a feeble attempt to explain the mechanism and how to keep it properly maintained. I'll be happy to e-mail a copy to anyone who replies to me at [email protected]

Please don't PM me as I only have time to log on here about once a week and I might miss it. Please use [email protected] for replies.

Basically, if you're landing or taxiing and worrying about your tailwheel, then the tailwheel isn't doing its job properly. Locking issues seem to be relatively common. One lister mentioned using oil instead of grease. Certainly oil is fine. Grease is fine also... if you clean and re-grease every 6 months or so. Otherwise it can harden and cause sticking problems. Ugh!

Having said all that, I have owned/flown RVs or Rockets with full swivel and old non-swiveling tailwheels. I am sold on full-swivel.

Naturally, I prefer our tailwheel which gives better clearance and handling. Doug Bell also makes a fine tailwheel. Get one or the other! 'nuf said.
 
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API. the only way to fly!

One RV4, One HR2. One with 1400 hours, the other approaching 1000, both with Aviation Products Incorporated dual fork tailwheels mostly operated off pavement in hostile surroundings. Unlike all the others, the API has higher ground clearance, better steering and doesn't easily clog up with mud or lodge rocks in between the tire and fork. See blog below.
I prefer positive steering all the time, but dislike chains. Therefore I use plastic-coated stainless steel cable from Ace Hardware with swaged ends and no springs. Works good, has lasted a very long time with no failures so far.

Great product:)

Smokey
HR2
http://blog.bowenaero.com/?p=88

AVIATION PRODUCTS INC 805-646-6042
 
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not needed

osxuser said:
I've only seen it on one RV... but anyone else consider a locking tailwheel?
Click to expand...

I fly my -4 quite often without the tailwheel springs ( totally free swivel). If the cross wind is bad enough that you need to lock the tailwheel, its (the tailwheel) going to just skid on the ground anyway.

The stearable tailwheel is more for taxi ops.

Chris M
 
Hello all,
Quick question somewhat off the subject---what is AN # of tail wheel retaining nut? Fiber in mine is too worn to trust.
Thanks,
Gene (20foxtrot)
 
an#

The nut for the "axle" bolt is a AN310-6. The nut on top of the fork is MS21083-N8....Hope this helps:):)
 
What grease and did you guys install a nipple ?

Hi RV'tors,

I just took the tailwheel assembly apart for cleaning and re-greasing. I usually use Shell 22 grease but I find it have to re-grease each 15 hours or so, it just doesn't last.. What grease are you using ??

This brings me to the next question... has anybody installed a grease nipple to avoid taken the assembly apart each time ? I have the original Van's tailwheel assembly...

Thanks !
Simon
 
PH-SCP said:
Hi RV'tors,

I just took the tailwheel assembly apart for cleaning and re-greasing. I usually use Shell 22 grease but I find it have to re-grease each 15 hours or so, it just doesn't last.. What grease are you using ??

This brings me to the next question... has anybody installed a grease nipple to avoid taken the assembly apart each time ? I have the original Van's tailwheel assembly...

Thanks !
Simon
Click to expand...

Hi Simon,

I think you will find that most people don't bother with the grease nipple and generally just remove it. If you don't have one, don't bother putting one in... it really doesn't do a good job. Preferred method is to disassemble and grease by hand. I use Aeroshell 5 or 6, but any grease is probably sufficient. Yes, and grease often. :)
 
If you remove the nearly useless grease nipple, replace it with a suitable screw. The grease nipple's only function, as far as I can tell, is to lock the bronze bushing against possible rotation.

This is one reason our tailwheel housing has a superior engineered plastic bushing. They're 3x the cost of bronze, but they don't have the drawbacks of the bronze, one of which is poor fit.

So, disassemble and clean the mechanism periodically. Grease or oil seems fine from my experience. And forget about greasing via the zerk... it is USELESS and will NOT lubricate the important locking pin, nor most of the shaft.

If you have any questions, email me at [email protected]

Vince
 
Pat Hatch said:
Hi Simon,

I think you will find that most people don't bother with the grease nipple and generally just remove it. If you don't have one, don't bother putting one in... it really doesn't do a good job. Preferred method is to disassemble and grease by hand. I use Aeroshell 5 or 6, but any grease is probably sufficient. Yes, and grease often. :)
Click to expand...

Thanks Pat.

I had hoped there was an easy way out. Guess not. On the other hand, it's a 15 minute job that get easier each time 'round.
 
I made my Tail Lynx setup loose from the start so I could have full rudder and not unlock the TW. Mine will unlock as needed if I am slow with a little kick.
 
PH-SCP said:
Thanks Pat.

I had hoped there was an easy way out. Guess not. On the other hand, it's a 15 minute job that get easier each time 'round.
Click to expand...

Very easy job as you said, and make yourself one of these cradles to make it even easier. I have found the cradle to be handy when you're on a creeper wiping down the belly, and for creating a better attitude for engine maintenance and for any inside-the-fuselage work you might have to do.

011.jpg
 
The heavier the tail weight the more wear you will get on the steering fork. My EVO has a heavy tail and I found myself changing the steering forks a couple of times a year. I took two of them to a metal hardening shop and had them heat treated. This made a huge difference and they would go over 150 hours after that. The last time one got a bit of wear I put a few drops of weld on the worn spot, gas weld, and then filed it to shape. This bit of weld proved to be very hard and i have had on wear on the part since then. Another think to do is to file the slot a few thou deeper. This will allow the pin to seat properly and reduce wear. Again I must add that this wear issue is almost a non event aircraft with a average to light tail weight. I clean and lubricate this area, oil or grease, every twenty five hours.
 
The control arms we make have a deeper locking pin notch in them as Tom described above.

We also have locking pins and springs, although most guys only need a new one if they lose the pin or spring when it pops out of the tailwheel during disassembly and gets lost in the gravel or grass. Usually you can simply dress down any burrs and move on.

I have 300+ hours on the tailwheel parts on my Rocket and have never so much as touched the locking pin or control arm. No significant wear at all. I suspect that the deeper notch in the control arm has much to do with that. Therefore, I've never seen a need to harden the locking pin.

It's all here if you want to read more info, need parts, etc.... tailwheel stuff

FWIW, guys regularly call me with locking problems with the RV Rocket steering link. These problems can almost always be eliminated by making the notch in the control arm deeper. Email me at [email protected] if you need simple instructions to do this.

The trick is to make the notch deeper, not wider.
 
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