Here's the LSA prototype on the scales.
The geometry and weight will change a little with the next iteration.

Thanks Greg!! Looks very well made and a viable candidate for sucking more funds out of my airplane units account.

If the coil-spring over shock system proves to be as light and performs as well, I think that could be a winner. Cover it with a bit of material like that snake-skin, and you've got a complete protection solution for the air shock. That should keep out the big stuff, and the little stuff.

It looks more streamlined to me, too (once the spring is covered up).

Is anyone with experience with this tail wheel suspension concerned with increased twisting loads being transmitted into the fuselage? The suspension seems to work beautifully in the vertical axis when traveling straight, but it appears to be quite stiff laterally, stiffer than the leaf spring it replaces. That, combined with its taller stance seems like it would stress the fuselage mounting structure more when encountering bumps while turning. Hopefully a non-issue, any thoughts?

A non-issue. It is much easier on the airframe. If you are turning, you are or should be going slow so lateral loads are minimal. The range of movement is larger than a spring so while accelerating or while loaded the height can be and usually is less than a spring. They are very adjustable so height can be varied depending on your preference.

NoCOpilot wrote:...but it appears to be quite stiff laterally, stiffer than the leaf spring it replaces. ...

I am not sure if that's true or not.

I am not happy with how little lateral flexibility my leaf spring provides, and I have snapped a tailwheel bolt due to lateral force on the tailwheel before. A stinger would be better in that regard, but I guess they are still little better than any other spring in general.

So at least this T3 in an improvement in one axis, if not both.

Shot video Testing the light sport suspension.
Tail weight 138 lb. with 1/2 tanks fuel.

http://youtu.be/IHJxt0b9mgA

Looks good! I was looking for any twisting on the airframe during hard turns. If there was any, it was very, very little. I can't see how there would be any more than with a standard tail spring.

Looks like it really soaks up the bumps!

What was this mounted on? I'm assuming this model is recommended up to LSA gross weights?

I don't really see how the loads on the fuselage attach points would be any different when turning vs rolling out straight down the runway.

I think the most important thing is having sound hardware, tight bolts, and lube in all the right places. I too have broken a tailwheel bolt in a rough off airport environment. I blame worn out hardware, or myself, that is.

Yeah, I was thinking the same thing Evan--unless your wheel doesn't swivel or you wallop the spring sideways or are running a skid, what difference does it make?

I however have to question your integrity calling my current runway "a rough off airport environment". The cows think you're back on the sauce as they have been packing it tight for years now.

I'm five minutes away from uncrating the new and improved T3 (LSA). I'll make another video next week so you can see the improvements.

wyomingiswindy wrote:Yeah, I was thinking the same thing Evan--unless your wheel doesn't swivel or you wallop the spring sideways or are running a skid, what difference does it make?

I however have to question your integrity calling my current runway "a rough off airport environment". The cows think you're back on the sauce as they have been packing it tight for years now.

I'm five minutes away from uncrating the new and improved T3 (LSA). I'll make another video next week so you can see the improvements.

Well, it is a fucking cow pasture after all....

You decide-



Either way, I would love to try out a T3 over a stock leaf any day.

wyomingiswindy wrote:Yeah, I was thinking the same thing Evan--unless your wheel doesn't swivel or you wallop the spring sideways or are running a skid, what difference does it make?

I however have to question your integrity calling my current runway "a rough off airport environment". The cows think you're back on the sauce as they have been packing it tight for years now.

I'm five minutes away from uncrating the new and improved T3 (LSA). I'll make another video next week so you can see the improvements.

NEXT WEEK?? Sooner, this thing has me all excited. interested to see the current version. I'm talking to Bobby trying to figure out the best way to get this thing on my Murphy Rebel. I think the measurements work, but will have to fab up a mount for the horizontal stab supports

Wow, that is rougher than I think it is. The cows have it nibbled down to golf course height now. I'm posting a non-relevant non-tailwheel video tomorrow with that field involved. I've got the T3 mostly installed. Dan incorporated nicer tail brace wires for me in this version as well as a couple other great things. Hopefully the brace wires might work similarly for a Rebel.

As many of you know, I’ve been testing the T3 Tailwheel Suspension (dual shock) on a Bearhawk since mid-January and now, after two months of flying with it, wanted to provide an update.



This was a heavy snow winter so initial testing was done on a paved and plowed runway as shown in this previously posted video.



I was very impressed by the performance and ability of the T3 to absorb landing impacts. Although I was confined to pavement early on, it was very clear that this was a big improvement over leaf springs.

The first chance to take it off pavement came with a camping trip to Death Valley. The two of us didn’t skimp on gear and with large distances between fuel stops we topped off with 70 gallons in Tonapah, NV, about 45 minutes from our camping spot, the Chicken Strip. We made an excursion without the camping gear to Stovepipe Wells and Furnace Creek the next day. Both are paved runways. The following day we loaded all the gear and headed to Panamint Springs (gravel strip), and Ballarat (dirt road landing). The Air Shocks performed very well. Maverick recommended Lizard Skins to cover the shocks so there would be less chance of getting minor pits and dings on the smooth shaft that the seals ride on.



http://shop.lizardskins.com/products/rear-suspension-boot

I removed air shocks to test coil overs, then went on a one week, 2,000 mile trip to Baja Mexico. Heavy loads of maximum 2,700 lbs takeoff weight, 2,500 lbs maximum landing weight; 3 people, baggage, and 70 gallons of fuel. We made over a dozen landings on well graded dirt strips and one off strip desert landing in Arizona plus numerous pavement landings.



Since then, I've made several landings on remote Idaho desert airstrips and several landings on Elko Mountain. I’ll soon post a video of the T3 taking a pounding in Nevada.

Finally, the video showing some landings and takeoffs on a Elko Mountain is up!



Both air shocks and coil overs perform well. Air shocks require checking and adjusting pressures each day before flight. Coil overs don’t and can be adjusted by adjusting the spring pre-load by turning the large adjustment nut at the base of the coil spring and also have a rebound adjustment knob. I was able to turn mind by hand with the tailwheel off the ground.

This video comparing drop tests of leaf spring, air shocks, and coil overs clearly shows why the T3 is such an improvement over standard leaf springs by absorbing impact energy and dampening rebound.



The weight is comparable with the OEM spring weight:

Leaf Spring – 5lbs
T3 with Air Shocks – 5lbs
T3 with Coil Overs - 6lbs
T3 Steering – 1lb

To install this on a flying Bearhawk, I had to modify the rudder steering arm which is welded to the rudder. On most other planes, this arm is bolted on instead, so the next section only relates to a Bearhawk installation. It is much simpler on Cubs and others.

First, I took the rudder off the plane and used an acetylene torch and pliers to bend the moustache shaped rudder steering arms to horizontal. Then, I cut them off about 1/3 of the length from the rudder attach point. This is done so the rudder can hit the factory stops. Otherwise, the horizontal arms hit the fuselage and prevent the rudder from hitting the stops. In total, this mod only took about an hour so it’s pretty easy to do.





Since I was adding steering, I next drilled and bolted a new steering arm, affectionately named the “batwing” and provided by Dan to the old rudder arm stubs.



Then I made and added 3/16 spacer that goes between the T3 mounting plate and the 2-hole mount point on the fuselage to provide a little more clearance. This may not be needed in all cases as the unit just bolts on.

The steering is still being fine-tuned on my plane, and while it isn’t really needed. It does make taxing easier, especially in cross winds.



So to sum this all up, both the air shocks and coil overs work well and make the ride much smoother, air frame stresses are reduced, and the pilot is much happier not feeling the spring induced jarring and bounces. The weight is comparable to a spring so that isn’t much of a change or concern. Steering is a take it or leave it, but I will admit it is nice to have for long x-wind taxis. I’ve been hoping to make more off airport landings, but this was a bad snow year for us so I haven’t been off airport as much as I would have liked. I have put it through some abuse (as shown in the to be posted video) and it has held up well. In the 35 hours I’ve flown with it, it has performed very well and is holding up great.

It is too early to tell what the maintenance frequency will be long term, but it is easy to take apart and reassemble. Since this system has more moving parts, I assume there will be a maintenance requirement, but the suspension performance is enough to justify it my opinion. With the leaf spring, I was re-arching that at least once a year, and after two re-arches I would just order a new spring to avoid breakage from metal fatigue, so even leaf springs, as basic as they are, required annual maintenance too.

We recently measured the static tail height against Cowdog's and Maverick's Bearhawk which has a new leaf spring on it (for now at least, they will soon be ordering a T3). The T3 on my plane vs theirs was 1/2-inch lower. Since the range of movement in the T3 is greater it will be even lower with additional weight or load from acceleration and/or up elevator. The point being the wing angle of attack would increase, potentially allowing for shorter takeoffs. Other planes maybe different, but that has been my experience to date.

The more landings I make with this, the more I like it; there is no going back to leaf springs for me.

Great report, thanks!

Wow, now that's a report! Thanks for doing this work. I still aspire to have a Bearhawk or something similar someday so this will save me a ton of failing and time/money.

Also, sorry if I confounded your T3 thread. I'll post the LSA in a different post next round. (And my report won't be that detailed).

wyomingiswindy wrote:Wow, now that's a report! Thanks for doing this work. I still aspire to have a Bearhawk or something similar someday so this will save me a ton of failing and time/money.

Also, sorry if I confounded your T3 thread. I'll post the LSA in a different post next round. (And my report won't be that detailed).

Wyo, thanks. No worries on my end and no need for 2 different threads; I think they compliment each other well. They are very similar, essentially the same system so having them both in one place may be handier for those looking for information.

I really wish I could post that video with along with the report, but the internet connection keeps dropping, it amazes me to watch how much the tailwheel takes when on the ground. Makes a good case for wheel landings. However when we cant, I'm glad to be rid of the leaf spring.

We should meet up sometime so you can take the Bearhawk for a spin.

Finally was able to upload the video I'd wanted to include with the above review:



These are a few landings and takeoffs from Elko Mountain. Some of them had never been landed before or only once previously. Winds were 0 to 20 mph and quite variable in direction, not a great day to fly. In the first landing, I had a 17 mph headwind until about 15-feet agl when I didn't. It was a dumb mistake on my end as I should have realized that would happen when I dropped below the ridge line.

The opening scene is looking back on the LZ where I made the first 1.5 landings.

Enjoy,
Mike

If I understand what you told me about the steering mod; the gas cylinder will be inverted, or under the horn, and the steering chains/cable will eliminate the spring, of course. Has this steering mod been produced or tested yet? What's the best guess when the tail wheel with the new steering will be available?

Cowdog wrote:If I understand what you told me about the steering mod; the gas cylinder will be inverted, or under the horn, and the steering chains/cable will eliminate the spring, of course. Has this steering mod been produced or tested yet? What's the best guess when the tail wheel with the new steering will be available?

Yes, you are correct, the cylinders will attach to the underside of rudder steering arms (batwing) and the other steering springs go away. The new batwing arrived and Dan shipped some lower compression gas springs, too so when those get here, I'll put it all together and we can go try it out. If you're around, ill stop by. Hop in with me and taxi around to see what you think. I'll have to defer to Dan regarding timing.