Bearhawk Tailwheels Tundra Tailwheels are finally Ready

[Enewton57]

It might on the 10" but let's discuss this for a minute. Generally speaking the larger the Tailwheel the more tendency to shimmy. The tailwheels have some friction built in anyway and I build the 10" with an extra wavy washer to increase the friction, so it hasn't been a problem. The key thing is making sure you have proper kingpin angle. Go back and take a look at the previously posted pictures of the tundra Tailwheel mounted on Mark's Bearhawk and see the kingpin angle. That is the proper angle with no weight in the airplane. Mark recently changed out his leaf spring because the old one had straightened out (relaxed) and the king pin was vertical with no weight in the plane. When he loaded the plane up with people in the back and baggage the 10" Tailwheel would shimmy. After he changes out the leaf spring to this one shown in the pictures, no more shimmy.

So a properly set up (proper kingpin angle) 8" or 10" Bearhawk Tailwheel built by us, has enough friction built in to not have a tendency to shimmy.

Adding more friction makes steering a bit harder. My fear is someone would have an improper kingpin angle, or loose mounting bolts and then compensate by tightening up the friction control.


Eric Newton - Long Beach, MS
Bearhawk Tailwheels LLC
Bearhawk Manuals

http://mybearhawk.com

[Battson]

I have never had a shimmy problem with my existing TW.
I would be willing to try the larger fork [and bearing] without the friction adjuster. I land pavement only a few times a year, and I can wheeley those landings. In fact NJB spends more time on beaches and rocks than pavement.

Eric, are you were interested in selling a "half kit"? What would the price be?

Jonathan

[Enewton57]

Hi Jonathan,

For the the forks, steering arm, tube and tire for the Tundra it would be $425. Go to this page and scroll to the bottom to order one.

http://bhtailwheels.com/catalog_2.html

[Battson]

Hi Eric,

Are you able to tell me what air pressure you have been running these at, how low can you go?

Obviously the air pressure is a balancing act:
- higher pressures mean less greater strength to resist the hard hits, and less chance of a flat tire (but those forces are transferred to the fuselage)
- lower pressures provide much greater cushioning, shock absorption, and greatly enhanced floatation on soft surfaces (width is important)

While both those points are important in the off-airport environment, I think the latter is much more important overall. Especially considering the most successful bush tail wheels are big, wide, and soft.

Jonathan

P.S. does the $425 fork assembly come with a wheel too, or just the forks? Thanks!

[Enewton57]

Hi Jonathan, I recommend people start off with 20 PSI on the Tundra and go from there. You could probably go down to 15 PSI if you want. The $425 includes tire and wheel along with all the bearings and spacers. It's basically everything except the Tailwheel body and top cap.


Eric Newton - Long Beach, MS
Bearhawk Tailwheels LLC
Bearhawk Manuals

http://mybearhawk.com

[Battson]

Hi Jonathan, I recommend people start off with 20 PSI on the Tundra and go from there. You could probably go down to 15 PSI if you want. The $425 includes tire and wheel along with all the bearings and spacers. It's basically everything except the Tailwheel body and top cap.


Eric Newton - Long Beach, MS
Bearhawk Tailwheels LLC
Bearhawk Manuals
http://mybearhawk.com

That is a great deal Eric, all those parts for so little cash!

What's more, 15-20 PSI is VASTLY superior to the 60-70 PSI (think rock-solid) of the smaller wheels. In fact, I believe that's comparable to what the Alaskan Baby Bushwheel runs at, from memory.

My last question is, what airspeed reduction have you (or Mark) measured as a result of fitting this tail wheel?

Do I just place my order on your website?

PS. If you could throw in the friction fitting, that would be great, I have a welder here (saves shipping the whole deal back to the USA).

[Enewton57]

To my knowledge it hasn't been measured yet - you might ask Mark. Yes, just order on the website. Http://bhtailwheels.com - shipping will be figured in when you select your country.


Eric Newton - Long Beach, MS
Bearhawk Tailwheels LLC
Bearhawk Manuals

http://mybearhawk.com

[Battson]

To my knowledge it hasn't been measured yet - you might ask Mark. Yes, just order on the website. Http://bhtailwheels.com - shipping will be figured in when you select your country.


Eric Newton - Long Beach, MS
Bearhawk Tailwheels LLC
Bearhawk Manuals
http://mybearhawk.com

Thanks Eric,

I spoke to Mark, he said that when the installed the Tundra tailwheel, they also installed the profiled horisontal stabiliser and changed the angle to three degrees. Overall the Bearhawk was 3-4 MPH faster after all those modifications.

So yes, it hasn't been tested by Mark. Do you know of anyone else who has installed the Tundra tailwheel on a flying Bearhawk?

[Battson]

I think this video is a common example of when the Tundra tailwheel would be useful.

We didn't video it, but we recently had a huge drama on a beach where the tailwheel was getting stuck in the same way, and putting us into an "uncomfortable" position of getting very close to some big surf.

[jaredyates]

I have been trying to get the performance loss testing done on mine, but I haven't worked out the logistics over the past two months. The weather has to be perfect, I have to be in town, and my wife has to be able to put up with me leaving the house before dawn and not helping get the kids ready for the day. I had not intended to test the tailwheel separately, in part because it would require yet another case of all of these conditions coming together, and in part because I doubted that the effects would be large enough to show up in that kind of testing.

[Battson]

The other thing I should have asked, for completeness, is what the weight increase is compared to the 10" wheel?

With that, plus all the above facts and figures, there is enough information for anyone interested to make an informed decision about whether this tailwheel suits them.

[Battson]

The tail wheel upgrade kit arrived this weekend, so I can answer my own question!

The weight difference between the 10" tail wheel and the Tundra 12" is 400g (less than 1 lb). That moves the CG aft by about 2mm (5/64 inch).

Switching out the assembly was easy to do, and took about 20 minutes. Although because my tail wheel body has suffered a good rock hit to the bearing housing, the outer bearing race is trapped inside. But because there is nothing wrong with the bearing, I decided not to replace it with the new one provided. It's nice to have a spare.

I haven't welded on the friction fitting yet. I do so few pavement landings, I don't think the shimmy will ever bother me. I can always fit it later, if my experience dictates otherwise.

The Tundra is noticeable a larger diameter and importantly much softer, it should roll easily over larger rocks and absorb more of the dynamic forces. I am certain happy with the increased footprint - evident in this photo below:


The wheel is also about an inch wider:


Personally, for what I am doing, I think this width should be satisfactory. The diameter is certainly as big as anyone should need. I wouldn't have been upset if it were even wider again, just because we recently managed to get properly stuck in quite soft sand - which cost me a lot of sand-blasted paint to pull her out (after we unloaded a lot of heavy gear).

I haven't had a chance to fly with it yet, appalling weather over the weekend.

[whee]

Curious what the width measures once mounted up and inflated. My tundra TW measure 4". I saw a Baby Bushwheel for the first time yesterday and the thing is way fat. Think the 400x4 is taller but at least an inch narrower.

[Battson]

Sorry I thought I had already mentioned it - it is exactly 4" wide.

The Baby Bushwheels seem to be closer to 6" wide, which would be impossible to sink into soft surfaces. I am thinking if I really try, I can still sink the Tundra tail wheel, but I doubt it would actually sink far enough to get properly stuck... the old 10" tailwheel would sink up to the axle quite often, sometimes deeper - which was enough to get it stuck (by which I mean it stops turning, and then you need power to lift or drag it out). Just terrible for the prop.

​As pictured the Tundra is at 20 PSI, I tried letting it down to 12, didn't offer much additional benefit in terms of floatation, but would greatly increase the risk of popping it... so 20 PSI it is.