Ultracrusier 41's failed suspension mod

[GyroRon]

Here is some pics of Barry shock set up... that didn't work. Shocks just won't support the weight, they bottom out with the rotors on.

[gyropilot]

Ron,

If Barry can modify the vertical support struts so they're more vertical (which probably means narrowing the landing gear), he'll likely be able to use those same shocks. He needs to lay it out on paper first though and crunch the numbers (or get help doing it), otherwise he's in for a lot of trial an error.

I used those same shocks on my Bee and they only compress 2/3 when fully loaded for takeoff (about 535 pounds), but I had to narrow my landing gear to achieve that.

Regards,

John L.

[donshoebridge]

John,

What amount of travel was there at 2/3 compressed?

[GyroRon]

I will ask him to visit this thread John, thanks. He just didn't like the bungee set up, he said the bushings in there were already toast with only a handful of hours on the machine.

[KDOG]

Can he get stronger shocks for it?

[GyroRon]

Maybe, but these were the strongest Shocks Northern Tool sells. They are made for a off road two seat go kart.

Barrys plans for now is to lengthen the tubes the shocks are bolted in to allow the gyro to still sit where it is supposed to sit even though the shocks are bottomed out. This way the gyro will taxi and takeoff and land without all four wheels on the ground as it is now. His logic is that even though the suspension is bottomed out with all the weight of the gyro and pilot on it, that during the landing event there will be some shock absorbing from the shocks and since Bensens and Brocks and RAF and so omany more have no shocks he thinks all will be okay.

My advise to him is to either put it back to the plans version with bungees, go to the new Starbee gear, replicate something like Johns that has been proven, or to just make it a rigid gear gyro and leave the shocks and all that stuff off - saves weight and less crap to break.....

Barry likes to tinker, and if he has a idea, he has to prove it to himself if it will work or not. Meanwhile........... He still hasn't taxied, crow hopped, or done much else as far as progress of getting into the air with the thing since a month or more ago when I posted pics of his first crow hop. I keep telling him to put the tools down and FLY!!! tinker later.... :)

[Cobra]

Ive always thought shocks are used to dampen spring oscillation, not support weight themselves. Springs are used to support weight.

For this application, a pair of air shocks might work well, otherwise, Id use a set of aftermarket automotive coil over shocks.

[scottessex]

What is the spring rating on the shock? Maybe a pair of springs off a motorcycle would work better.

[Ralph]

If his bushings were trashed, he needs to look at how well they were greased and make sure the slot edges are smooth.

The best use of his time right now is to put the stock gear back on and fly the darn thing!

Ralph

[KDOG]

AMEN!!! I don't know if you've seen the progress I've made on my bee, Ralph. I was going to wait and see how Barry made out with his gear and then try to do what he did if it worked, but I think I'll just go with the bungees so I can get flying next year!!! I was wondering if I could use 3/16th aluminum for the cluster plate, comments anyone?

[Brian Jackson]

AMEN!!! I don't know if you've seen the progress I've made on my bee, Ralph. I was going to wait and see how Barry made out with his gear and then try to do what he did if it worked, but I think I'll just go with the bungees so I can get flying next year!!! I was wondering if I could use 3/16th aluminum for the cluster plate, comments anyone?
Kevin,
Did you mean Shock Plate? Cluster plates are sold by StarBee Gyros in 3/16" AL, but to my knowledge Shock Plates are only sold as 1/8" 304 stainless. My guess is to keep it as a stainless steel part. Just make sure you get the inside surfaces of the slots as smooth as possible.

Cheers,
Brian Jackson

[KDOG]

Yes, shock plate, my fault. I guess I should get the stainless plate.

[ultracruiser41]

Now, now, everyone calm down.....this isn't rocket science! The shocks mounted directly in-line with the diagonal gear struts could not support the dead weight of the machine with the rotors on...I will be installing a set-up much like the Starbee system which will allow the gear legs to support the weight and the shocks to act as "shock absorbers".

All this could be done easily if the gyro was at my home shop..but..since it's at the hangar and we don't have electicity yet, I have to measure a little, go home and cut, fit a little, go home and change..etc...etc.

Once this gear is done there is officially no more tinkering on the bee and only flyin' left to do! (well..maybe except for the.....just kiddin' Ron!!)

Ron's not a tinkerer so he'll never understand that tinkering is part of the fun !!!

Barry(love to tinker)K

Hey Ron, I've got an almost new Huscavarna leaf blower for sale with only about 120 seconds of run time on it !!! :rolleyes:

[gyropilot]

John,

What amount of travel was there at 2/3 compressed?Don,

Those spring/shocks have 3" of total travel until they bottom out. Mine are compressed 2" at normal takeoff weight. However, the compression rate isn't linear.

I have a copy of a weight to compression chart for those spring/shocks on my work PC and will post everything tomorrow.

Best regards,

John L.

[Ron Marlett]

Here is a link you might find interesting to help you visualize the suspension geometry. I stumbled across this one while doing some other research but found it to be pretty close to the landing gear numbers I had calculated for my "WannaBee"

http://www.kreuzotter.de/english/efeder.htm

You can set the spring rate up for pounds of force per inch but you will have to convert the static load applied to the end of the suspension(axle) from pounds to Newtons to enter it into that field. All your suspension dimensions will also need to be converted to MM for entry(24.5MM/Inch).

Once you set up the basic info, you can drag the shock attachment points around to see what config will give you the best travel/static load compression.

Ron

[gyromike]

Here's the load vs. compression chart for the Azusa shocks.
John sent it to me a couple of weeks ago.

[birdy]

You could use air bags. :D
The ones I fitted to me RAF are spoton,with bout 5" travel it makes most rough dirt roads feel like bitumen and they are easly adjusted for weight changes with pressure from regular tyre pump. :)

[rehler]

Birdy,

What is the brand name of your "air bags" or the place where can I buy them?

Are they on the internet somewhere?

Thanks.

[donshoebridge]

Looking at the chart, that spring starts out at about 200 pounds per inch, but then it jumps to about 450 pounds per inch. IMO, the 200#/In would be at the lower end of "exceptable" for an ultralight, but to be of any use, should have a travel greater than 3 inches to do the job. 200#/in with 4 inches of travel would be fine for only landing loads on an ultralight. Any aircraft over 254 pounds would be better off to have a spring rate of 200-300#/in. The 450#/in would be ok for a REAL heavy gyro if there was more than a 1/2 inch of travel.

One thing to keep in mind, if the spring is at an angle to the wheel travel, your spring requirement will be greater. Example: if your spring is mounted at a 45 degree angle to the wheel travel, you would need a spring rate closer to 400#/in to acheive 200#/in at the wheel, and if your spring has 2 inches of travel, you're going to see wheel travel closer to 4 inches. This assumes that you have the spring force applied at a point that is almost right on top of the wheel. Moving that point in-board will increase the spring requirements.

My first suggestion would be to double-up on the coil-over springs. With the "compression strut" angle on the GBee (first images) being greater than 45 degrees, the 200#/in coil-over is going to be less than 100#/in at the wheel.