Industrial airbag suspension system as shocks on Sport Copter gyros?

[Kevin_Richey]

Any Sport Copter gyro owners interested in trying Dennis Dubois' industrial airbags as replacement to the rubber donuts/grommets that come with the SC kit? They possibly would be slightly smaller than the Sparrowhawk/RAF initial ones.

He first introduced them on his "View Master" gyroplane he designed and then built. I moved my gyro to the same grass strip Dennis flies off of. In certain places it is rough, shaking my machine quite a lot. I asked Dennis how his View Master takes the grass strip , and he replied it is like driving a '58 Caddy!

If these airbags work so well, then there'd be less roughness transmitted through the controls stick, bearings, and rods, which would mean longer-lasting components. Those components are essential to our lives while flying! I can't help also thinking that they'd offer a smoother ride while trailering the machine, too!

Dennis built three sets for Sparrowhawk gyro owners last month. Brad Moore is the first to test them and says they are a 100% improvement over stock.

He needs to have at least three owners to step forward and put a deposit down to start another production run. Approximate cost is to about $300. I'm wanting to try a set. Anyone else?

The first photo below is one I took at Scappoose airport when Dennis flew over to meet me for a flight. You can see the airbag on his landing gear strut going up to the airframe from the axle. He also has a smaller one to cushion the nose wheel.

The additional photos below stolen from Brock Steiner's Sparrowhawk "Shredo" thread on this forum.

[scottessex]

I have a set of Firestone bags I was wondering about using... Mounting may be an issue how do they stay inline with the gear?

[bmoore2156]

Kevin,
As you know the airbags have 3'' of travel. That computes roughly to 9'' of cushioned travel at the wheel. The takeoffs are different because the machine rises as weight is taken off the landing gear. It's not a bad thing, just something to get use to.
I also think it will take a lot of the stress off the gyro while I am trailering it because I use tire tie downs.
I have dropped in from around 4' on landing and it's really smooth. With the other gear I am sure it would have folded up.
Dennis has definitely built a better mouse trap.
Brad

[Kevin_Richey]

Brad: Notice much difference on paved runways vs. before w/ the Sparrowhawk rubber discs?

Was the 100% improvement only for grass strips?

Can you answer Scott's question regarding the ability to stay inline?

Dennis may chime in, too.

[bmoore2156]

Kevin,
Most of my testing has been on paved runways. I landed in Lakeside last weekend on their unmowed strip. I took off next to the runway because the grass was only 12'' tall instead of 20''+ on the runway. I didn't notice the rough ground before my takeoff and it was very bumpy but doable with the new struts.
The ability to stay inline is because the strut passes though the center of the airbag and the top tube slides inside of the lower tube with a bushing. It also has slot so that you can have mechanical stops. The bags are designed to operate in a certain range and are not suppose to be inflated without a load. If you didn't have a limit on how far they would expand, then after liftoff they would expand too far.
Brad

[gyrojake]

What stops the recoil? seems as though they would bounce like a pogo stick. I see no dampers to slow down the recoil. Unless the overall load is at the threshold of recoil.

[scottessex]

OK, the airbags I have are just "bags" not "donuts" Thanks for the clarification,
And I'm with Jake, do they bounce?

[BEN S]

Kevin,
I'm interested in them, but so far I have abused my shocks more than I should have and they always have worked well. I don't mind the price but I'm not sure how they would make much more of a difference.
Do they develop leaks over time? does the rubber become hard? is there any maintenance needed? And is there any mods that can't be easily undone if I think they are too springy?
How does it affect your tracking down the runway, is it straight and true or do you bounce side to side as it goes?
I would like to know these things before I go messin wit sumptin whats ain't broke!
Ben S

[bmoore2156]

Ben,
I can tell you that dropping in from 4' was a teeth jarring experience with my old gear. I did it once in my first few hours of instruction. The radio even fell out of the dash. I think it surprised my instructor too! Even tho my landings have improved since then its nice to be able to do drop in landings with less airspeed and ground roll and still have soft landings. I can't say if they will improve your SC as I have not flown the vortex.... Yet
As far as bounce, I have not been able to get it to bounce yet. But my machine is heavy and that may make a difference. Ground track is no problem, but I also have a steerable nose wheel so I can't say for a castering setup. I would expect it wouldn't be a problem. The best part of the airbags is you can adjust the air pressure to your liking.
I'm sure they are going to last just at long as it takes for a tire to get dry rot. Mine are set so I could take off and land with the bags flat, just in case.
I will make a video and post it in the next few days.
Braf

[BEN S]

Thank you for the report,
I would like to know if anyone has tried them on a comparable model though.
It's not that I am against trying something new, but like I had said there isn't anything about my older rubber grommet style that has made feel they weren't up to the task.
One time while practicing spot landings in front of the hanger, I misjudged my height above the dirt windrow at the end of the runway and just as I was getting ready to flare, I clipped both my rear wheels on the top of the dirt berm. Of course my front wheel smacked the deck pretty hard and I gouged the dirt real bad with my mains, but the rig took it with zero damage. Would the air bags make a difference? I don't know but I won't be grading the runway with my mains again anytime soon.

[Dennis D]

Hi Scott.
A few pictures should help you see what’s keeping them aligned.

Hi Jake and Ben.
I’ve only buggered up two landings hard enough to bounce. The rebound was present but it seemed to be only a few inches and then it just settled back in. The idea in using these struts is to make the take off run and taxying smoother, there just isn’t enough travel to cushion landings.

Brad is the only one that has a base line to judge from, he has hundreds of hours using the stock suspension. When I first started taxying the Viewmaster, I purposely overfilled the bags which extended them up against the upper stops. The Viewmaster has a rigid mast, so I felt every bump and hole in the paved taxi way through the cyclic stick. As soon as I lowered the pressure and let the suspension start to work, 99% of that feed back went away. That’s the only reference I can offer.

[Kevin_Richey]

Hey Ben: On paved surfaces and runways, the Sport Copter rubber cushions work fine. A few times I taxied over some ROUGH grass at the Scappoose airport and it shook my head enough that I didn't want to do that again. Smoother grass areas there were OK.

The airstrip we're at now has some average grass-strip-grass, and some really rough areas that I don't appreciate!

So, after watching him taxi and then take off one day, and noticing his machine wasn't bouncing around, or up and down, I asked Dennis how his air bag suspension does there, and his reply about it being smooth like a '58 Caddy made me sit up and take notice.

I think the idea here is to try them out w/out having to destroy the current strut/rubber shock set up, so we could easily change back to the original if we wanted to.

Originally Posted by BEN S

Kevin,
I'm interested in them, but so far I have abused my shocks more than I should have and they always have worked well. I don't mind the price but I'm not sure how they would make much more of a difference.
Do they develop leaks over time? does the rubber become hard? is there any maintenance needed? And is there any mods that can't be easily undone if I think they are too springy?
How does it affect your tracking down the runway, is it straight and true or do you bounce side to side as it goes?
I would like to know these things before I go messin wit sumptin whats ain't broke!
Ben S

[Kevin_Richey]

The mentioned price of somewhere around $300 is a fair range estimate, based on the fact that the single place gyro would use a slightly smaller air bag, with an accompanying lower price. Depends on how many would like to participate.

The larger air bag suspension for the heavy two-place gyros is a bit more for the heavier-duty air bag.

[bmoore2156]

Ok, here is the video I promised. I have not watched it yet because there is a small wait until it's ready to view. I hope the quality is ok. Sorry it took so long, my computer took a crap and had to wait to get it fixed.
All of these landings look normal and smooth. I assure you, a couple of them are only smooth because of the airbags!!
Brad
RAF 2000 Gyroplane with new airbag suspention - YouTube

[Dennis D]

Brad
Those are some sweet approaches, I could watch you do that all day long.
Thanks very much for all of the testing work you’ve done. Now if we can just get rid of that pesky squeak.