Xair shock absorbers

[BillLipson]

Hi Everyone

 

I want to replace the shock absorbers and springs on my Xair's main wheels. They look a bit like motorcycle gear. Anyone got any ideas re what they are or had experience buying/replacing them? Thanks

 

Bill

[waraton]

I know a bloke...I will talk to him tomorrow. PM me your contact number Bill.

[Downunder]

They are probably "mountain bike" shocks.

There's various sizes on ebay. 190 x 50mm DNM DV22AR Coil Spring Rear Shock For Mountain Bike Bicycle for sale online | eBay

Any info on make/model written on them?

[BillLipson]

Thanks Waraton

I'm a bit new to this. How do I private message you my contact?

Bill

[BillLipson]

They are probably "mountain bike" shocks.

There's various sizes on ebay. 190 x 50mm DNM DV22AR Coil Spring Rear Shock For Mountain Bike Bicycle for sale online | eBay

Any info on make/model written on them?

Thanks Downunder,

I will see if I can get a serial number etc off them

Bill

[FlyBoy1960]

They are motorcycle shocks made by Amstrong in India. I helped fit a set only a few weeks ago at our airfield.

 

That's the trouble when you wander around aimlessly on a Saturday morning at the airfield, you get put to work!

 

I remember having a good look at the box that they came in when I was putting it in the bin for the owner, it had the name Armstrong and made in India written on the box. They are way, way more stiffer than any mountain bike shock absorber.

 

I pushed my 100 kg body on top of them and they wouldn't even budge, I guess the aircraft is around 300 kg and when they are mounted they didn't compress at all with the weight of the aircraft, they only compressed with the pilot seated in the aircraft and then only a few millimetres I'm guessing. They must be for a pretty heavy motorbike because they are heavy, I'm guessing a couple of kilograms each.

 

They were replacing a set of fournales (I think that is the spelling) they were a nitrogen filled shock absorber but instead of having a spring on the outsidethey just worked with oil and gas. The chrome on the main shaft which I am guessing is about 30 mil diameter had started to peel off after about 15 years and it allowed the gas to escape because it damaged the seals. They looked like a very short motorcycle fork if that helps but the owner replaced them with conventional shocks because he said the other ones were no longer made. The gas shock absorbers would be lucky to weigh 500 g each so they were very light in comparison to what was put back on. To replace the shock absorbers on both sides only took around 25 minutes total time, the engine didn't even cooldown and the owner headed back to Boonah.

[onetrack]

Fournales still produce a lot of shock absorbers - was it just that particular model of Fournales that is no longer available? The Fournales can be rebuilt, couldn't he get any rebuild components?

 

http://www.mawsolutions.com/html/fournales_shock_absorbers.html

 

Heavy landings will produce a very substantial increase in loading on suspensions, due to the shock component.

 

If you operate a loaded crane, and drop the load just 50mm, then stop it again, the loading on the crane and components increases by 100%.

[facthunter]

Forces on the compression stroke will affect transmitted forces on the structure. Control of rebound is important with aircraft. You may also require rubber limit stops and a progressive spring. IF it coil binds or reaches a stop that doesn't have a bit of "give" it may damage the structure.. Nev

[FlyBoy1960]

The schock that were fitted had a progressive spring, more coils at the bottom and less at the top and it had a tappered rubber stopper at the top as well, from memory, say 15mm thick. I will be at the airport next Saturday and will ask if anyone is interested

[waraton]

This is what my mate has done, woks well, If you put the mouse pointer on my name Waraton click start conversation and flick me a phone number so the owner of the aircraft can call you. I gave him a heads up and he is happy to share his experience which he described as "basically simple". This machine never sees bitumen and operates of some rough dirt strips.

 

[BillLipson]

Thanks Everyone for your advise. It has been really helpful and especially to Waraton ( I have messaged you my phone contact)

Bill

[waraton]

Hi Bill PM received and has been forwarded, he will point you in the right direction. Happy to help, I regularly seek advice from the collective knowledge of this group. Lucky to have it!

[WinneyBuh]

Good days for All!😇 Can I pullup this theme again? Now I 'm repairing X-air S, and have the similar problem.

Can anybody say, what is the length of main shock absorbers? I need the distance between centres of holes, when aircraft is standing on the ground.(Now  I have set of some ones, looking like from 'Honda Dio', but they have 260mm in free state. My craft is now completely disassembled and I can't measure this distance in assembly). 

Another way to solve is to know the model of shock absorbers, described in upper messages or model of bike they are from.

Great thanks for any answer.🤝

Edited August 16, 2023 by WinneyBuh
Grammatic error

[BrendAn]

i have an xair standard. i will be going to the airfield on saturday. i can measure them and see if they have any sort of i.d on them if you want.

[WinneyBuh]

Wau!!! That is impossible joy, геаlly!

😇🤝

[WinneyBuh]

...and can you make photo from left or right side, to see the pitch angle on the ground? If this is not difficult to you. 😟I can't understand, what modifications were made with previous owners.

[BrendAn]

6 hours ago, WinneyBuh said:

...and can you make photo from left or right side, to see the pitch angle on the ground? If this is not difficult to you. 😟I can't understand, what modifications were made with previous owners.

Ok

[FlyBoy1960]

I had access to, and flew an X-Air owned by our club, great little plane.

 

We looked around to find replacement shock absorbers and we spent more than the price of the originals in trialing some from a motorbike and some from a car neither of which worked. We needed to get replacement shock absorbers because of a really long taxi over rocky ground. It eventually wore out the rubbers in the ends of the shock absorbers that couldn't be replaced.

 

The ones off motorbikes are not designed for an aircraft that weighs 500 kg, they were way too soft even with the springs packed out, even with nobody in the aircraft it sat down on its tail with a shock absorbers fully compressed.

 

Someone else sourced a set from some sort of dune buggy but they were way too hard and you might as well have put pipes in where the shock absorbers should have gone.

 

Just buy the originals and problems sorted.

[FlyBoy1960]

12 hours ago, BrendAn said:

i have an xair standard. i will be going to the airfield on saturday. i can measure them and see if they have any sort of i.d on them if you want.

They are made by Armstrong in India to the specifications of xair according to the box the new ones came in, if i remember correctly. The main member who looked after the plane tried for weeks to get them from Armstrong without success.  This was about 15 years ago now but things might have changed.   There is also a french supplier of an air shock but they are way expensive and the crome plating came off the shaft in less than 12 months letting the nitrogen escape. 

 

There is more on this on the xair support website.    [email protected]

[BrendAn]

50 minutes ago, FlyBoy1960 said:

They are made by Armstrong in India to the specifications of xair according to the box the new ones came in, if i remember correctly. The main member who looked after the plane tried for weeks to get them from Armstrong without success.  This was about 15 years ago now but things might have changed.   There is also a french supplier of an air shock but they are way expensive and the crome plating came off the shaft in less than 12 months letting the nitrogen escape. 

 

There is more on this on the xair support website.    [email protected]

It's not me that wants them. I am just supplying some measurements and photos.  I did replace my front coil overs . I have a contact at xair India to get parts direct. The new parts I got from the factory were  Gabriel brand.

[skippydiesel]

On 07/06/2020 at 6:18 PM, waraton said:

This is what my mate has done, woks well, If you put the mouse pointer on my name Waraton click start conversation and flick me a phone number so the owner of the aircraft can call you. I gave him a heads up and he is happy to share his experience which he described as "basically simple". This machine never sees bitumen and operates of some rough dirt strips.

 

Look very much like the single, trailing arm, shock on my sons KTM dirt bike.

 

Dirt bikes are subject to huge suspension stress & have compression/rebound  adjustment, so are a likely contender for this application. 

[facthunter]

Some of the  motorcycle single shockers are quite heavy and have short stroke. They are also expensive. Many planes have used bungee springs (Austers) but without some form of damping can bounce you into the air even on take off on a rough field. A properly damped leg makes life easier. It's pretty easy to bounce a C 180. (steel spring legs) You can use  nitrogen filled as a spring (until it leaks out).  Nev

[skippydiesel]

 

55 minutes ago, facthunter said:

Some of the  motorcycle single shockers are quite heavy and have short stroke. They are also expensive. Nev

Pure speculation on my part :

 

• Weight is almost as much an issue in dirt bikes designed for competition riding, as in aircraft - so would expect shocks to be as light as possible, consistent with duty.
• Dirt bikes generally have a lot of travel/movement  in the suspension - the shocks are designed to accommodate this.
• Cost - no idea but unlikely to be as costly as anything designated for aircraft use

[WinneyBuh]

Now I'm from phone, it's not convinient to write. Somewhen at evening I'll write my view of this problem from desktop with some digits.😇 P.S.: I'm educated as aviation designer and have experience of designing and building of hanggliders, trike-wings and reanimation of Tiphoon TL-32 and Skywalker II aircrafts.

Sincerely yours

Yury A. Bukharkin

Moscow. Russia.

62 years old😇

[facthunter]

The single shock rear suspension is a link system The actual shock has only a short travel The dual shocks likewise attach about 2/3 the way down the swing arm.  This is related to motorcycle parts  A moe suitaable motorcycle soureced component might be using a front fork.  One side slider).  4 inches of wheel Travel  easily available and you need  good rubber bump stops. Nev

Edited August 17, 2023 by facthunter