Me Likes my new BH Tailwheels Tundra Tailwheel

[John Bickham]

About 8 days ago I installed my new BH Tailwheels Tundra tailwheel. I removed my 10" BH Tailwheel that had served me well and I had abused to a great extent. After 19 stop & go landings, on mostly hard surface, I'm really pleased with my new Tundra tailwheel. I was really expecting the Tundra to shimmy more than the 10" on hard surface just due to the extra mass factor. The opposite is true for me. The Tundra tailwheel has not had one shimmy in those 19 stop & go's. The 10" would have complained a couple of times due to pilot technique.

Took a few measurements if''n some might be interested:

20220123_150046[1].jpg

Weight - 10" = 6.28 lbs Tundra = 7.33 lbs This is good weight for my forward CG, O-540 BH 4A. I can take a couple of the extra water bottles out at the aft bulkhead.

Tail height increased 1 3/4".

Spinner (tip) height decreased 9/16" at 35 psi in Tundra tailwheel.

I know that doesn't seem like a lot of "lowering the nose" but I'm grateful for every fraction of an inch of "over the nose" visibility due to some to the off airport strips I frequent.

Before tundra: 20220119_101945[1].jpg


After tundra: 20220131_162514[1].jpg

Tried to take these from the same spot for comparison. I'm very happy with the improved over the nose visibility. A little bit is a big deal to me.

The other added benefit is cushion of the tundra as the tailwheel drops. I call it the "poor man's T3". The 10" at the recommended 50 psi was bit more abrupt and harder on the airframe.

The 10" will be cleaned up, serviced and on standby for long XC's with General Aviation destinations. It doesn't take a lot of time to swap them out.

THANKS ERIC!!!!

[Enewton57]

Thanks John, glad you like it. Thanks for the write-up. Enjoy!

Eric Newton
BearhawkTailwheels LLC

https://bhtailwheels.com

[Craig Van Sickle]

About 8 days ago I installed my new BH Tailwheels Tundra tailwheel. I removed my 10" BH Tailwheel that had served me well and I had abused to a great extent. After 19 stop & go landings, on mostly hard surface, I'm really pleased with my new Tundra tailwheel. I was really expecting the Tundra to shimmy more than the 10" on hard surface just due to the extra mass factor. The opposite is true for me. The Tundra tailwheel has not had one shimmy in those 19 stop & go's. The 10" would have complained a couple of times due to pilot technique.

Took a few measurements if''n some might be interested:

20220123_150046[1].jpg

Weight - 10" = 6.28 lbs Tundra = 7.33 lbs This is good weight for my forward CG, O-540 BH 4A. I can take a couple of the extra water bottles out at the aft bulkhead.

Tail height increased 1 3/4".

Spinner (tip) height decreased 9/16" at 35 psi in Tundra tailwheel.

I know that doesn't seem like a lot of "lowering the nose" but I'm grateful for every fraction of an inch of "over the nose" visibility due to some to the off airport strips I frequent.

Before tundra: 20220119_101945[1].jpg


After tundra: 20220131_162514[1].jpg

Tried to take these from the same spot for comparison. I'm very happy with the improved over the nose visibility. A little bit is a big deal to me.

The other added benefit is cushion of the tundra as the tailwheel drops. I call it the "poor man's T3". The 10" at the recommended 50 psi was bit more abrupt and harder on the airframe.

The 10" will be cleaned up, serviced and on standby for long XC's with General Aviation destinations. It doesn't take a lot of time to swap them out.

THANKS ERIC!!!!

Enjoyed hearing this! I have one for my LSA build and look forward to seeing how it does in the soft sand.

[whee]

My Tundra TW has been very good too. No shimmy, steers nice and just works. I wanted more AOA so I swapped the tire out for one that is wide but short.

83005903-1FE8-4E27-A81D-E06139564254.jpg

[rodsmith]

What is the diameter of your tire?

[Nev]

Tail wheel shimmy

How do I go about fixing a shimmy issue ? I first noticed it after landing on gravel yesterday as I rolled onto tarseal about 25kts, and it really kicked the aircraft around with an initial hard turning force to the right. Several others were watching (fellow Bearhawkers) and the tailwheel was turning through 360° which matched what I felt from the drivers seat.

Later when I was landing on gravel, an observer saw it happen again. This time I didn't feel any indication, which made me wonder if it had been happening more often without me knowing. The aft attachment bolts had some wear at about 30 hours, so I now suspect it may be caused by a shimmy that I couldn't feel.

Any advice on how to correct this is appreciated. Obviously not landing on tarseal where possible is the first step.

[Mark Goldberg]

First thing check to make sure all bolts are tight. The angle of the "kingpin" of the tail wheel sometimes gets wrong and can contribute to shimmy. But that should not be the case with your situation. Mark

[500AGL]

As Mark said check your attachment bolts but the bolt angle in the head is the main cause of shimmy, especially on pavement. Tire size/design plays the second role - A baby bush wheel for example is very difficult to not have shimmy on pavement, but it rarely does on soft ground. (Airframes Ak just created a shimmy dampener for it, but that seems like a bandaid perhaps)

[Bcone1381]

In addition, as weight on the tailwheel increases, like a cg shift aft with a big load in the aft baggage and 2 adults in the rear seat, it loads up the tailwheel spring a bit more and effects the king pin angle. More weight means a less stable king pin angle.

[whee]

Nev, Are you running the Tundra? Big tailwheel tires have a tendency to shimmy. If you have the Tundra then you can adjust the bass bolt that pushes on the kingpin. This is meant to add just enough resistance to stop the shimmy. Mine required just enough resistance that the tailwheel didn’t pivot freely. It didn’t chance the feel when taxiing but when pivoting the tw by hand you can feel the resistance.

[Nev]

Thanks Whee - yep mine is the BH Tundra.

[Nev]

Thanks guys. Is there a way to change the angle of the kingpin ? It looks to be fixed. I'll adjust the friction bolt and see if that helps.

[jaredyates]

I would guess you could remove the stinger, heat treat it back to soft, bend it, then heat treat it back to springy, but that sounds like a lot of to-do. What is your static angle like now? You want the top of the pin to be aft of the bottom of the pin at your heaviest load.

[Nev]

I'll measure the angle and get back to you Jared. I'm sure there will be a solution.

[Mark Goldberg]

The tailspring can be bent without heating it. But since yours is pretty new Nev I would be surprised if it was already needing a bend. Mark

[Battson]

This is a factory setup as per the design. The kingpin has the correct angle, I checked myself, noting the exact angle isn't specified.
If there's a kingpin angle issue, then it's likely to be widespread.

Jon has posted the solution which was designed into the tailwheel, which is friction on the main bearing. When I upgraded mine years ago, Eric explained that without correct friction shimmy would be an issue.

[robcaldwell]

What is the protocol for tightening the friction tensioner to the kingpin? Is it finger tight, then X degrees further with a wrench?

[Battson]

Refer to Jon's experience above, in lieu of reading the instructions provided with the wheel

[schu]

It’s just a pinch bolt, I suspect tighten until it doesn’t shimmy.

as for 35 psi, I wonder how that will hold up. On my 170 with a Scott 3200 with abi fork, it must have 50psi or I get flat tailwheels. Went through a few tubes until I sorted it out. Speaking of tubes, it’s nice t have a spare. If you don’t, and get a flat, you’re grounded for a week instead oh how long it takes to locate a jack plus 10 minutes.

[robcaldwell]

Keeping a spare tube handy is a great idea! I visited Eric's site, but did not see spare tubes offered for sale. Where did you source your spare tube from?

[Battson]

as for 35 psi, I wonder how that will hold up.

This applies to the 10" Tundra BH tailwheel:

I have been running around 30 psi and trying to stay above 25 psi at best, although we do drop below on rare occasions.

I haven't had a flat yet, touch wood, although the tailwheel does take the occasional heavy hit, to the point the bearings have all failed and needed to be replaced, and the body cracked and had to be welded - so just a few heavy hits.... Still running the same wheel + tire + tube though, it's never let me down and never left me stranded.

Those who fly to protect their tailwheel in off-airport situations, are running lower pressure.

[schu]

Where did it crack? It would be great to have a data point on how these fail when abused.

[Battson]

It's not useful data, the crack was in an unexplainable location which should not experience any shear or tension. Even Bob couldn't understand it. We assume a freak flaw from the welding process

[Enewton57]

Hi guys, a few comments.

Mark is correct that the kingpin angle shouldn’t be a problem on a new kit built with a new tail-spring, but check the angle anyway. Loaded to full gross weight and aft CG, the kingpin angle should be either perpendicular (vertical) to the ground or slightly tilted aft at the top.

Yes, the rod spring can be slightly bent cold to achieve the correct angle but shouldn’t be necessary on a new kit with a new tail-spring.

Try different tire pressures to see what works best.

There should be a small amount of drag when spinning the tire. Tighten axle nut accordingly.

Tighten the friction bolt until you feel it come against the kingpin and go fly it. Repeat tightening a little then test flying, until shimmy is reduced or eliminated.

I’ve spoken with Bob at length about this. Larger tires tend to shimmy more because of the larger mass. Bob recommends, If you feel shimmy upon landing, lighten the tail with forward stick until the airplane slows down. Most of us are taught to to keep the stick all the way back after landing, so this goes against your basic training, but it’s an effective way to stop a shimmying TW.

I hope something here helps,

Eric Newton
Bearhawk Tailwheels LLC