What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Thinking of Changing Tailwheel Fork

S

StuBob

Well Known Member
I have the stock tailwheel, with the forward pin (or whatever it’s actually called — the vertical swivel part) very close to the ground. I’m interested in getting one of the aftermarket forks that angle down, lifting the pin a little higher. Also considering a pneumatic tailwheel, as I have a long taxi.

The questions:
1) Which aftermarket forks are generally considered the best? I don’t want to exchange a fork that‘s too low for one that shimmies.
2) Will a new fork lift the tail enough to alter takeoff and landing?
 
StuBob said:
I have the stock tailwheel, with the forward pin (or whatever it’s actually called — the vertical swivel part) very close to the ground. I’m interested in getting one of the aftermarket forks that angle down, lifting the pin a little higher. Also considering a pneumatic tailwheel, as I have a long taxi.
The questions:
1) Which aftermarket forks are generally considered the best? I don’t want to exchange a fork that‘s too low for one that shimmies.
2) Will a new fork lift the tail enough to alter takeoff and landing?
Click to expand...
I switched to "Aviation Products" tailwheel assemblies many years ago and love them. I've used them on several homebuilts and on my Legend Cub.
They raise the tail enough to improve over the nose visibility, but not enough to alter take off and landing characteristics. Never had a shimmy problem.
 
StuBob said:
I have the stock tailwheel, with the forward pin (or whatever it’s actually called — the vertical swivel part) very close to the ground. I’m interested in getting one of the aftermarket forks that angle down, lifting the pin a little higher. Also considering a pneumatic tailwheel, as I have a long taxi.

The questions:
1) Which aftermarket forks are generally considered the best? I don’t want to exchange a fork that‘s too low for one that shimmies.
2) Will a new fork lift the tail enough to alter takeoff and landing?
Click to expand...

I switched my 7 to the Bell fork from Flyboys along with their Deluxe tailwheel tire. Much smoother ride with that tire and improved ground clearance over the Vans stock setup. Also, no bearing worries with that TW tire. I have just ordered the JD Air fork for my 8 since it is lighter with similar clearance to the Bell fork and is less expensive than the Flyboys fork. I will be trying the Vans light weight TW tire, but if I don't like the ride I will change to the Deluxe TW tire.

As mentioned above, slight improvement in over the nose vis with no noticeable difference in TO or landing and no shimmy with the Bell fork. I expect similar performance with the JD fork.
 
The Bell fork is the only one that won't catch on something if you roll your tailwheel over it (like dropping it off the edge of the taxiway, etc). The tire hits first, so the wheel will pop up over any obstacle, perhaps with a bit of power. The others all have hinge points that drop significantly below the stinger, that will catch and bind.

I put together this comparison many, many moons ago showing the various geometries, but half the photos are gone now because we didn't have a good photo hosting option back then.

Tailwheel Upgrade

PM Sent Message sent, check your PM
vansairforce.net vansairforce.net
 
Last edited:
It's a little like asking what's your favorite color. ;) It just depends on what's important to you and personal preferences. I installed the Bell tailwheel fork primarily because an experienced RV-6 driver told me he saw the standard Van's tailwheel shear off a tail spring rod when someone dropped their tailwheel off the edge of the concrete when pivoting around to do a run-up. That vertical face can be an effective stop if the wheel drops off into the grass. This is exactly what Snowflake is referring to.

The Bell version is a sturdy unit and is well made. With that said, I'm sure the other alternatives are good as well.
 
It’s pretty easy to chop most of that low hanging pin off at an angle that won’t snag on the ground. Simply weld flat plate over the wound and paint. Easy, inexpensive and effective.
 
Tried the Bell fork, but sent it back since it was reducing the fuselage's ground attitude by 1.5°. Going into some sub 1000ft runway, I wanna have max AOA, and anything helps.
Replaced the Van's tailwheel with a Flyboy's aftermarket, ordered a new fork from Van's and welded a small triangular steel piece, the whole assy now being lighter than before, same angle, and the welded wedge works super ;)
 

Attachments

  • IMG_6512.JPG
    IMG_6512.JPG
    350.7 KB · Views: 42
  • IMG_6513.JPG
    IMG_6513.JPG
    114.1 KB · Views: 42
Dan 57 said:
Tried the Bell fork, but sent it back since it was reducing the fuselage's ground attitude by 1.5°. Going into some sub 1000ft runway, I wanna have max AOA, and anything helps.
Replaced the Van's tailwheel with a Flyboy's aftermarket, ordered a new fork from Van's and welded a small triangular steel piece, the whole assy now being lighter than before, same angle, and the welded wedge works super ;)
Click to expand...
I hope it does work, but it looks to me like if you dropped that over the edge of a taxiway, the wedge would just make a lever arm that turns the entire wheel sideways.

1.5 degree change in deck angle corresponds to just over 6" lift of rise at the tailwheel. The Bell fork does not lift the back of the plane 6". Maybe 2" at best, or half a degree.
 
The Aviation Products forked frame (left) is quite good, but like most is subject to pivot bushing and shaft wear, even with regular greasing. Flew one for several years, good reliable unit:

Tailwheels 800w.jpg

Switched to a JD Air unit some years ago and continue to like it very much. The shaft is supported on a ball bearing/needle bearing arrangement. Near zero friction, and no wear.

About the same practical curb clearance, but allows a bit more AOA.

JDA.jpg
 
Last edited:
I have the Bell. To Dans point, it does raise the tail slightly. Good for a tad better visibility over the nose in a 6, but occasionally I will hit tailwheel first on a high performance short field landing.
Enough to make a difference on short field? Would I still hit with the standard tailwheel fork? Somebody smarter than me would have to chime in.
I’m comfortable with short runways regardless and other factors reign more important, field type, obstacles, winds, etc….. still, like Dan said, every little bit helps.
 
DanH said:
The Aviation Products forked frame (left) is quite good, but like most is subject to pivot bushing and shaft wear, even with regular greasing. Flew one for several years, good reliable unit:

View attachment 59316

Switched to a JD Air unit some years ago and continue to like it very much. The shaft is supported on a ball bearing/needle bearing arrangement. Near zero friction, and no wear.

About the same practical curb clearance, but allows a bit more AOA.

View attachment 59315
Click to expand...
If I ever wear my Bell out, this is the way I would go. They offered me a free demo when they first came out to test but it never showed up. Guess they got enough “testers”.
 
Snowflake said:
The Bell fork is the only one that won't catch on something if you roll your tailwheel over it (like dropping it off the edge of the taxiway, etc). The tire hits first, so the wheel will pop up over any obstacle, perhaps with a bit of power. The others all have hinge points that drop significantly below the stinger, that will catch and bind.

I put together this comparison many, many moons ago showing the various geometries, but half the photos are gone now because we didn't have a good photo hosting option back then.

Tailwheel Upgrade

PM Sent Message sent, check your PM
vansairforce.net vansairforce.net
Click to expand...

Not quite accurate. Our Screaming Eagle fork gives similar clearance as our Bell fork, i.e. the steel parts are above the axle line of the tire. In other words, if the tire will roll over it, the steel parts should have no problem.
 
vfrazier said:
Not quite accurate. Our Screaming Eagle fork gives similar clearance as our Bell fork, i.e. the steel parts are above the axle line of the tire. In other words, if the tire will roll over it, the steel parts should have no problem.
Click to expand...
The Screaming Eagle is an improvement over the stock fork, but it doesn't have anywhere near the clearance of the Bell. The lowest point on the Bell pivot components are not just above the axle, they are almost entirely above the body of the tire.

Here are the Screaming Eagle fork, and the Bell fork, with a red line added to show the length of the vertical hard point that can catch if you drop over the edge of a taxiway, and a green line to show the clearance from the front of the hinge hardware to the ground. Both have the liability of the lower part of the Van's knuckle, but the Bell fork only has about 0.25" below that. The SE has about 1.5".

1711475995410.png
1711476896991.png

And it gets even better with the API tailwheel, which has almost no knuckle below the stinger.
1711477183856.png

Edited to add the JD Air fork for comparison. Clearance on it is pretty much the same as the Bell, with one important difference: There's effectively a hook at the top (double red line). Tie-down cables, non-square taxiway edges, etc. The bearing may turn nicer than the bushing style, but it does add a small liability. If they could weld a triangle in there between the bearing housing and the tube that attaches to the stinger, it would fix that.
1711634041541.png
 
Last edited:
Back when I built my RV-6, the Aviation Products full swivel was the only full swivel option. You do NOT want the single arm fork version as after a few hard landings, it will bend and the tire will wear on one side. The dual arm fork works perfect.

As Dan Horton stated, the aluminum will wear and need to have a bushing inserted. Never noticed much wear on the much harder steel fork but the softer aluminum will wear over time. After wearing out the bushing and needing another bushing replacement, I switched to the Bell tailwheel and like it just as much. There is NO bushing in the Aviation Products mount as it comes from the vendor.

What tail wheel fork will bring many opinions much like primer.
 
azrv6 said:
Aviation Products out of Ojai, CA. Pretty much out of business and non-responsive.
Click to expand...
Unless things have changed VERY recently, they are still in business…. Just slow. Best to email them and they will usually get back to you in a day.
 
DanH said:
Switched to a JD Air unit some years ago and continue to like it very much. The shaft is supported on a ball bearing/needle bearing arrangement. Near zero friction, and no wear…
Click to expand...
Is this bearing housing/yoke dimensionally identical to the Vans fork shaft? I see that the JD drawing indicates the upper needle bearing is ONLY used with the JD fork - otherwise you are to use the plain bushing. Just wondering why that is specifically called out.
 
Toobuilder said:
Is this bearing housing/yoke dimensionally identical to the Vans fork shaft? I see that the JD drawing indicates the upper needle bearing is ONLY used with the JD fork - otherwise you are to use the plain bushing. Just wondering why that is specifically called out.
Click to expand...

I asked Darwin (JD Air) about that several months ago. This was his reply:

"Our yoke has dual bearings, roller bearing on the bottom, needle bearing on top. There is a spacer in the middle. This combo of bearings supports side to side and up and down loads. No bushings. It works with all aftermarket forks. As long as it was greased it will be fine. Be sure to service every oil change....

...We install the bearings. I need to update the instructions."

I guess he's yet to update the instructions.
 
Snowflake said:
The Bell fork is the only one that won't catch on something if you roll your tailwheel over it (like dropping it off the edge of the taxiway, etc). The tire hits first, so the wheel will pop up over any obstacle, perhaps with a bit of power. The others all have hinge points that drop significantly below the stinger, that will catch and bind.

I put together this comparison many, many moons ago showing the various geometries, but half the photos are gone now because we didn't have a good photo hosting option back then.

Tailwheel Upgrade

PM Sent Message sent, check your PM
vansairforce.net vansairforce.net
Click to expand...
You missed the JD Air fork.. that one is sweet, with the bearings and clearance angle. I have the lightweight tire, it never wears and like the name said, it’s light weight. The Bell and inflatable tire are smoother and quieter if you have rough taxiways, but then you have to worry about another tube to go flat. They also raise the tail and provide better “over the nose” visibility, but you can’t land it as slow with the reduced AOA on landing.. if you always wheel land it, then it’s not a problem but I don’t like the idea of another tube to maintain.
 
Taltruda said:
but you can’t land it as slow with the reduced AOA on landing.. if you always wheel land it, then it’s not a problem
Click to expand...
I would like to see this born out. A three point landing is a full stall landing. Done “perfectly”, if “greasing it on” is your goal, you’re stalling right at the point all three tires are just touching down, or slightly before.
We establish stall speeds in the air, the speed at which the airplane stalls. It doesn’t change unless your configuration changes. There’s no ground to get in the way.
So, are we saying your stall speed changes if your tail wheel puts your tail a slight bit higher?
Your tailwheel may hit first, but if you’re stalled, landing is over. There is no difference in speed.
These are more questions than answers or arguments.
My landing speed with the Bell tailwheel never changed when I upgraded. I will hit tailwheel first but only on a high performance short field landing. In that scenario, I am not trying to “grease it on”, I’m trying to stall and “plop” on the runway.
Help me understand why landing speeds are higher in a full stall landing if your tail is a bit higher.
 
JonJay said:
I would like to see this born out. A three point landing is a full stall landing. Done “perfectly”, if “greasing it on” is your goal, you’re stalling right at the point all three tires are just touching down, or slightly before.
We establish stall speeds in the air, the speed at which the airplane stalls. It doesn’t change unless your configuration changes. There’s no ground to get in the way.
So, are we saying your stall speed changes if your tail wheel puts your tail a slight bit higher?
Your tailwheel may hit first, but if you’re stalled, landing is over. There is no difference in speed.
These are more questions than answers or arguments.
My landing speed with the Bell tailwheel never changed when I upgraded. I will hit tailwheel first but only on a high performance short field landing. In that scenario, I am not trying to “grease it on”, I’m trying to stall and “plop” on the runway.
Help me understand why landing speeds are higher in a full stall landing if your tail is a bit higher.
Click to expand...
Full stall landings cannot be done properly with an RV. The stall attitude is higher than the 3-point attitude. If you do a full stall landing, the tailwheel will touch first and the mains will plop down and pretty hard. Rvs should be "attitude" landed. Get a mental picture of your attitude in 3-point. This should be your touchdown attitude.
 
Thx Mel.
It makes sense then that slightly lower tail would get you a bit slower and closer to stall, thinking not much though.
Yes, the “plop” in a high performance short field landing isn’t pretty.
Watch the Valdez record holders and you can see some impressive “plops”, with highly modified gear and mushy tires. Tailwheel always hits first.
 
JonJay said:
I would like to see this born out. A three point landing is a full stall landing. Done “perfectly”, if “greasing it on” is your goal, you’re stalling right at the point all three tires are just touching down, or slightly before.
We establish stall speeds in the air, the speed at which the airplane stalls. It doesn’t change unless your configuration changes. There’s no ground to get in the way.
So, are we saying your stall speed changes if your tail wheel puts your tail a slight bit higher?
Your tailwheel may hit first, but if you’re stalled, landing is over. There is no difference in speed.
These are more questions than answers or arguments.
My landing speed with the Bell tailwheel never changed when I upgraded. I will hit tailwheel first but only on a high performance short field landing. In that scenario, I am not trying to “grease it on”, I’m trying to stall and “plop” on the runway.
Help me understand why landing speeds are higher in a full stall landing if your tail is a bit higher.
Click to expand...
Like Mel said, we really don’t full stall the RVs with Tailwheels.. The stalling attitude is much higher than the 3 point allows.. a taller Tailwheel makes it even further from a full stall. Occasional I’ll do a one wheel tail first landing on purpose, and if done softly, the mains don’t plop that much, but if you held it to a full stall it will plop pretty hard. I enjoyed my time with that tall, inflatable Tailwheel.. it was on a -7 and it was really easy to teach on it. Very quiet to taxi on.
 
Taltruda said:
Like Mel said, we really don’t full stall the RVs with Tailwheels
Click to expand...
With all due respect, and not feeling the need to turn this nice thread in a popcorn throwing contest, the -8 I'm flying gets into a full stall with the tail wheel touching Terra Firma a smidge before the mains hit.
For the rest of the short legged fleet, getting into a real short field will require a high AOA (or speed) over the fence, and yes, the mains will slam down.
To keep this undesirable effect to a minimum, I strive to keep my tail as low as possible (...) ;)
 
Dan 57 said:
With all due respect, and not feeling the need to turn this nice thread in a popcorn throwing contest, the -8 I'm flying gets into a full stall with the tail wheel touching Terra Firma a smidge before the mains hit.
For the rest of the short legged fleet, getting into a real short field will require a high AOA (or speed) over the fence, and yes, the mains will slam down.
To keep this undesirable effect to a minimum, I strive to keep my tail as low as possible (...) ;)
Click to expand...
You’re right about the -8s being closer to a 3 point in a stall.. I feel that most of the buffet is really from the gear leg intersection than the actual wing stalling though. My comments were really directed to the RV-7, as that’s where the OP posted. I have a long leg -4, and it 3 points nicely, but no where near stall.. same with the -7s and 6s
 
The OP, StuBob, has probably been struck by the wealth of experience and knowledge available on the very VAF...

But one very important argument we overlook, is drag or efficiency! The higher the tailwheel fork post, the lower your tailwheel will hang in the breeze. And the greater that unwanted drag :oops:
One way to offset tailwheel drag is to use some skateboard wheely, or install a small skid iso of the tailwheel, or integrate the tailwheel into the rudder fairing or lower rear fuse, or better still, install one of those sexy little tailwheel fairings as originally sold by Van's.
Now anyone please feel free to verify the exact calculation I made, but a 1" increase of the post's length will result in a drag penalty lowering the top level speed by 0.07861 knot.

Coming next will be how to develop and use an appreciative eye to better judge the appeal of a steeper ground stance...
 
I've done this conversion on several RVs and the only thing you will notice is forward visibility in the 3-point attitude. Landing characteristics are so minor that you will not notice. AND, if the added drag bothers you that much, simply replace the tailwheel with a tail skid!
 
StuBob said:
I ordered a JDAir. Will report back if there's anything worth saying.

Thanks, all!
Click to expand...
I love the JD Tailwheel but I bought the flyboys double arm with the tiedown hole and their extended bolt for the towbar.. I can’t find where they sell the two hole arm separately, but they used to.
 

Attachments

  • IMG_4006.jpeg
    IMG_4006.jpeg
    711.2 KB · Views: 10
  • IMG_4007.png
    IMG_4007.png
    560.2 KB · Views: 9
Taltruda said:
You missed the JD Air fork.. that one is sweet, with the bearings and clearance angle.
Click to expand...
Edited to add it.

I still maintain that the Bell is the best option for maximum clearance and minimum risk of getting stuck somewhere, *without* modifying the stock knuckle. The API fork is best if you don't mind replacing the knuckle (which means somehow aligning the existing holes in the stinger with the new knuckle). The JPI is a very close second though, they just need to fill in that hook feature above the bearing.
 
Mel said:
I've done this conversion on several RVs and the only thing you will notice is forward visibility in the 3-point attitude. Landing characteristics are so minor that you will not notice. AND, if the added drag bothers you that much, simply replace the tailwheel with a tail skid!
Click to expand...
This.

(and a tail skid would add braking at the rear of the aircraft once you're down, too, which would help reduce the tendency to ground-loop...)
 
Taltruda said:
I love the JD Tailwheel but I bought the flyboys double arm with the tiedown hole and their extended bolt for the towbar.. I can’t find where they sell the two hole arm separately, but they used to.
Click to expand...
Blake still has the double sided control arm with tiedown but they are presently sold out. I have one on my RV-6 and one on the shelf for my RV-8 project.
 
Dan 57 said:
The OP, StuBob, has probably been struck by the wealth of experience and knowledge available on the very VAF...

But one very important argument we overlook, is drag or efficiency! The higher the tailwheel fork post, the lower your tailwheel will hang in the breeze. And the greater that unwanted drag :oops:
One way to offset tailwheel drag is to use some skateboard wheely, or install a small skid iso of the tailwheel, or integrate the tailwheel into the rudder fairing or lower rear fuse, or better still, install one of those sexy little tailwheel fairings as originally sold by Van's.
Now anyone please feel free to verify the exact calculation I made, but a 1" increase of the post's length will result in a drag penalty lowering the top level speed by 0.07861 knot.

Coming next will be how to develop and use an appreciative eye to better judge the appeal of a steeper ground stance...
Click to expand...
Do you have an uncertainty estimate for that top level speed decrease calculation? :p
 
Snowflake said:
The Screaming Eagle is an improvement over the stock fork, but it doesn't have anywhere near the clearance of the Bell. The lowest point on the Bell pivot components are not just above the axle, they are almost entirely above the body of the tire.

Here are the Screaming Eagle fork, and the Bell fork, with a red line added to show the length of the vertical hard point that can catch if you drop over the edge of a taxiway, and a green line to show the clearance from the front of the hinge hardware to the ground. Both have the liability of the lower part of the Van's knuckle, but the Bell fork only has about 0.25" below that. The SE has about 1.5".

View attachment 59320
View attachment 59335

And it gets even better with the API tailwheel, which has almost no knuckle below the stinger.
View attachment 59337

Edited to add the JD Air fork for comparison. Clearance on it is pretty much the same as the Bell, with one important difference: There's effectively a hook at the top (double red line). Tie-down cables, non-square taxiway edges, etc. The bearing may turn nicer than the bushing style, but it does add a small liability. If they could weld a triangle in there between the bearing housing and the tube that attaches to the stinger, it would fix that.
View attachment 59498
Click to expand...
Maybe Darwin could add a "Wire cutter" like you see on some helicopters, just in front of the rotor hub and on the bottom before the skids -- just cut the offending wire :)
 
bjdecker said:
Maybe Darwin could add a "Wire cutter" like you see on some helicopters, just in front of the rotor hub and on the bottom before the skids -- just cut the offending wire :)
Click to expand...
But how fast would you need to be taxiing for it to be effective? :)
 
Snowflake said:
The Screaming Eagle is an improvement over the stock fork, but it doesn't have anywhere near the clearance of the Bell. The lowest point on the Bell pivot components are not just above the axle, they are almost entirely above the body of the tire.

Here are the Screaming Eagle fork, and the Bell fork, with a red line added to show the length of the vertical hard point that can catch if you drop over the edge of a taxiway, and a green line to show the clearance from the front of the hinge hardware to the ground. Both have the liability of the lower part of the Van's knuckle, but the Bell fork only has about 0.25" below that. The SE has about 1.5".

View attachment 59320
View attachment 59335

And it gets even better with the API tailwheel, which has almost no knuckle below the stinger.
View attachment 59337

Edited to add the JD Air fork for comparison. Clearance on it is pretty much the same as the Bell, with one important difference: There's effectively a hook at the top (double red line). Tie-down cables, non-square taxiway edges, etc. The bearing may turn nicer than the bushing style, but it does add a small liability. If they could weld a triangle in there between the bearing housing and the tube that attaches to the stinger, it would fix that.
View attachment 59498
Click to expand...
Rob,

While it may be true that the impact point on the various steel parts varies, it is the forward face of the tire that we should be concerned with when placing those green and red lines. If the face of the tire smacks into a pothole, curb, or other unmovable object, you're apt to bend or break things. IMHO, hitting the steel parts on something is bad, but smashing the forward face of the tire into something can be just as bad. Either one will likely get your undivided attention. 😲
 
vfrazier said:
While it may be true that the impact point on the various steel parts varies, it is the forward face of the tire that we should be concerned with when placing those green and red lines. If the face of the tire smacks into a pothole, curb, or other unmovable object, you're apt to bend or break things. IMHO, hitting the steel parts on something is bad, but smashing the forward face of the tire into something can be just as bad. Either one will likely get your undivided attention. 😲
Click to expand...
True! If you're moving at speed and hit something like that, you might be having a bad day shortly thereafter with *any* of these setups.

The situation i've found myself in a couple of times was accidentally dropping my tailwheel off the side of a taxiway when turning to do a run-up. When that happens, and the wheel is the contact point, I find it will roll up and onto the surface easily with a tiny bit of power. But if the metal knuckle gets caught, the pavement edge grabs it and it just won't release... At least i've been too chicken to give a high enough burst of power with the stick forward to make it happen.

An old bold pilot once told me to just hold the brakes, add power, and use the elevator to raise the tail a few inches... Then release the brakes and you should roll forward and the tail will drop onto the pavement because you don't have the holding force at the main wheels anymore. It may work, but that's a level of finesse that I don't think I have... I like my prop and don't want to polish another one. :)
 
Snowflake said:
Edited to add the JD Air fork for comparison. Clearance on it is pretty much the same as the Bell, with one important difference: There's effectively a hook at the top (double red line). Tie-down cables, non-square taxiway edges, etc. The bearing may turn nicer than the bushing style, but it does add a small liability. If they could weld a triangle in there between the bearing housing and the tube that attaches to the stinger, it would fix that.
Click to expand...
Agree, but easy fix with a couple of pieces of titanium sheet. Added primarily to provide a tie down anchor, this should give some skid plate protection as well. Easy add.

IMG_20240419_195336133~3.jpg
 
Last edited:
Toobuilder said:
Agree, but easy fix with a couple of pieces of titanium sheet. Added primarily to provide a tie down anchor, this should give some skid plate protection as well. Easy add.
Click to expand...
Nice! That definitely does it. Good use of the existing bolts to mount it as well. Although, I can think of a few ways to wrap a rope around the stinger for tiedown without needing a hole...
 
You must log in or register to reply here.
Back
Top