landing gear that can take a beating and not collapse

akholland
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landing gear that can take a beating and not collapse

Post by akholland »

Was wondering if anyone has drawings, links, research info, issues, or ideas about designs for some tough landing gear with as much suspension as possible and modern shock technology.

What are advantages to compression shock over top of gear vs longer oleos or some other designs.

I see a potential compression buckling failure issue with the just planes or Franken maule design? Has anyone heard of a trailing arm design similar to the old Polaris edge chassi? I'm sure there are lots of designs out there

Does the extended heavy duty gear that they sell give you more travel? and how high can It be dropped from without damage?

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Maulehigh
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Post by Maulehigh »

Would this do? :lol:

http://imageshack.us/f/824/mg6613q.jpg/

Might affect C of G though :shock:
David
'91 MX-7-180

akholland
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Post by akholland »

Ha perfect

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Post by akholland »

http://db.tt/qZkWYfZs

http://db.tt/hTmPFKHt

Anyone bored enough to check my statics computation? I get Tension T1 in the oleo at 3360lb and compression in the gear leg of T2=4125lb at gross weight of 2500lb just sitting (1g). I've assumed measurements since I'm bored at work and dont have plane in front of me. At 3g that's like 10,000 lb of compression in the stock gear leg... Wow .. is my math off?

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Post by akholland »

rem
Last edited by akholland on Sat Sep 07, 2013 2:00 am, edited 1 time in total.

akholland
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air shocks with 10 to 18". travel

Post by akholland »

https://lorenzindustries.com/theshockgu ... k_2_0.html

Says will support 1000 lb per corner. I assume these might be a little undersized but its all I found so far

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crbnunit
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Post by crbnunit »

How would you account for prop clearance whit 18" of suspension travel? You could crank up the spring rate and the compression dampening on a shorter travel system but that would just transfer the load to the airframe and other suspension components.

I hadn't really thought about it until now, but how much added travel is available with the extended gear? It uses the same springs, so shock travel is not increased but there will be more travel at the wheel just because the longer gear covers more distance for the given amount of spring travel. How much more? I'll leave the calculations to one of you guys!

I have found the Maule gear to be extremely effective and forgiving on and off airport. I'm sure this is no small part because of the big, shock absorbing bushwheels. What we have is a pretty good trade-off of strength and weight.

It would be nice to get a company to wind us some olio coils out of titanium.... Save us a few Lbs. There is a company out there doing this. I'd be curious about the cost and weight difference. Not a PMA part mind you...
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pilot
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Post by pilot »

Some thinner coils would gain us more shock travel, probably a few inches of actual wheel travel. The old square springs really didn't give much travel at all - the round ones are way better. Likely that poor oleo maintenance is to blame for a lot of gear collapses, but not as much as pilot error :)

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Post by akholland »

If I knew the extended and compressed length of an oleo, I could calculate the travel. I asssume its likely around 3 inches ?

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Post by akholland »

I was looking more at 10 or 12" travel as a target... With 18" not only is prop clearance and visibility a problem but it might want to roll in a stiff crosswind taxi or sidehill.

I think I heard the hd extended gear was like 6" wider correct? 3"/24"=12.5% more travel roughly ? So if it was 5" total it would be like 5.5".... Not a significant improvement if travel is the goal. .

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crbnunit
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Post by crbnunit »

Another thing to consider in the quest for longer travel is wheel deflection. The only way I can think of to combat this is to abandon the olio/a-arm setup in favor of a suspension that keeps the tires traveling parallel to the load rather than deflecting to the side. At the extreme end of travel, the side load on the axles would be pretty severe.

I'm pretty sure the FrankenMaul was set up this way with the wheels traveling straight up and down?

As you say, I'm betting sidehilling with this setup is pretty exciting!

Maybe a better way to think of all of this is to have better control over the setup we have. Adjustable preload and dampening wouldn't be outside the relm of possibility.
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Post by akholland »

That would be nice to use hd extended gear with slightly longer travel oleos. Im not aware of any commercially available tension shocks? Anyone ever seen any ? Maybe stack weld two oleos inline! That would potentially let the geometry out too far though. The Franken maule just had a regular a frame gear. Another idea is to use two radius rods and a trailing arm like a Polaris edge or skidoo summit chassi. Use one of my old bent wing struts for the arm and connect it to the bolt on rear float fittin with a ball joint. That would be interesting but lots of drag potentially

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Post by akholland »

Finally got the M4-210 torn down again for an attempt at designing some new landing gear... I keep staring at this collapsed stock gear thinking I need to make an attempt at a JustStol Design or a trailing arm design.

Who's got some extra R&D $ they want to donate? lol I need to get my hands on some air shocks. Looking at the King Air shocks 2.5 series. Their $395 each. and support 1200lb a piece.

http://www.buykingshocks.com/airshocks/

I would start with drop tests by picking it up with the excavator and dropping the weighted frame from different heights building to above gross weight for a safety factor.

I'll use the Axles from My stock gear and weld on the new arms to that.

Once I get a design that works, I would also be springing for a crank flange adapter to run a Catto prop. They only make a catto with a Lycoming SAE-2 flange. Apparently Saber mfg makes the adapters. The Catto should keep the crank flange from bending if the gear collapses and take some weight off the nose with a fixed pitch.

any takers?

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crbnunit
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Post by crbnunit »

I've got some 11" travel Kings I'm note using at the moment... LOL! What about something like an OV-10 Bronco suspension with a trailing link? That kind of setup solves some of the above mentioned problems and soaks up punishment pretty well.
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akholland
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Post by akholland »

A travel king shock is a coil over and would be too much drag. An air shock is more sleek and weights much less.

A reverse trailing link would be nice. Connect it at the rear float attach fitting location. I think this would be the simplest design.

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