Hi guys. I'm Vince Frazier. I make the full swiveling, STEERABLE tailwheel fork mentioned above.
The reason that I sat down, created an account, and am replying to this thread, that was shared with me by a Onex builder, is that there are a LOT of misconceptions talked about in the comments above. Please let me clarify exactly what our tailwheel will do.
A local Onex builder, Todd Reifers, asked me if I could make a smaller, lighter version of our Screaming Eagle full swiveling, STEERABLE tailwheel fork that can be found on hundreds of Van's RVs. I told him that I could and asked him for various dimensions, AND we discussed ways to add differential braking. Todd took care of the differential braking with a very simple, very clever heel brake installation that uses the stock cable brakes. I produced the smaller tailwheel, which is designed to use a 4" DJM lightweight solid rubber tire. Together, they make a nice upgrade to the Sonex/Onex steering and ground handling.
Now let me explain how the tailwheel works, because what is indicated in the comments above are somewhat misleading. First off, it absolutely has positive steering and only unlocks when rudder input is hard over to the left or right, AND when the tailwheel tire has force against it, such as when turning into a parking space. It is very unlikely to come unlocked on the runway since the tailwheel tire should be mostly in trail. It is very unlikely to come unlocked at any time without the side force typically seen only at slow, tight turning speeds and with simultaneous full rudder input too.
So, no ground loops due to tailwheel design! Sorry, ground loops are still due to pilot error, stuck brake, too much wind, poor main gear alignment, etc.... but I can't help but point out that the stock Sonex brake design certainly doesn't give you the extra anti-groundloop benefit of differential braking! Having said that, there is nothing wrong with the stock set up. But it doesn't turn very tight, does it?
How does our tailwheel steer and swivel and stay locked and come unlocked at the appropriate times you ask? Inside the body of the tailwheel mount housing are a locking pin, spring, and a cam type groove. The locking pin positively engages the control arm. The control arm engages the rudder horn via a push rod AND simultaneously engages the tailwheel fork for positive steering. And the rudder is controlled by your rudder pedals, of course.
Under normal, straight-ahead, conditions, you can't disengage the steering unless you shear the pin!! So, yes, this system is every bit as positive steering as the stock Sonex non-swiveling tailwheel.
So, when does it unlock and swivel you ask? Well, only when it's supposed to, unless something is worn, broken, etc. When is it supposed to unlock you ask? Only when: 1) you have slowed down to a slow taxi speed, such as when parking, and step on full rudder, or 2) when you're pushing the aircraft backwards and the tailwheel fork swivels past the lock limits and the pin disengages.
Take a look at the photo on this page:
http://www.flyboyaccessories.com/Tailwh ... p/1109.htm
It doesn't show the control arm, or the steering rod, etc. but it's the only photo I have online. Nonetheless, it should help clarify the operation of the unit.
In the past several months, we have built a few units for other Sonex/Onex builders too. Todd says he is very pleased with his new tailwheel and brakes. I don't know if Todd Riefers is on this forum, or if he is available through any of the Sonex/Onex contacts or builder's lists. I would hope that others can contact him directly for his input.
We also make several other tailwheels, mostly for the RV guys, with various tire diameters up to 7.5" Any of the RV tailwheels could be adapted to the 0.635" OD Sonex spring (stinger). However, the RV mounting angle is slightly different, so the pivot wouldn't be vertical unless the spring (stinger) were intentionally bent. It's easier to simply use a mounting socket specific to the Sonex/Onex. We make those too, of course.
Hope this clarifies the way the tailwheel works. For more info please contact me directly at
vincefrazier@gmail.com I'm not routinely on this forum, so please email instead of sending a PM.