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Wittman type tubular steel gear

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orion

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Recently we touched upon tubular steel landing gear as associated with the Wittman airplanes and as now used by RV and others. Someone here posted a link to an Oregon fabricator of that gear but I can't seem to find it. Anyone?

Thanks.
 
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Turd Ferguson

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Re: Whitman type tubular steel gear

They are not "tubular"

It's a solid rod turned with a taper. I just made a set for a future project, very easy to make and it's an excellent gear design.
 

rtfm

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Re: Whitman type tubular steel gear

Hi,
Sounds just like the sort of thing I will need for my gear. I have plans for the Sonex, and note that they use titanium rods for their landing gear. I priced this material locally and nearly fell of my chair. 4130 will have to do, thank you very much. I was hoping to use the same dimensions for my project, but since titanium is out of the question, I don't really have much to go on as far as 4130 dimensions are concerned.

Any rules of thumb on this?

My little solo Razorback will be very small and light - estimated MAUW less than 500lbs

Duncan
 

PTAirco

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Re: Whitman type tubular steel gear

I had a pair made recently and I am very happy with the work and the service.

I paid $550 for the pair, custom made to my sketches. After agonizing about the cost for ages, I decided that was it a solution worth the price.

Mine are a little unusual in that the top part is bent to fit into a horizontal socket (and it fit perfectly I might add) and the lower part is straight. Usual practice is to bend the axle part from the leg, mine use separate welded sockets for the axles. Allowed me to fiddle around with the toe-in and get it right. It worked well, but drilling the upper mounting hole (3/8" dia - it sees a hefty torque load) was torture. The stuff is HARD. It wasn't really feasible to rig the whole thing under a drill press, so I had to do it with a hand-held drill. I pilot drilled with 1/8" and thought I'd creep up on the final size, but it really seemed best to go straight for the final size, minus a reaming allowance. The drill will center much better.

It took a careful combination of moderate pressure and moderate speed to keep the drill cutting and I had to re-sharpen the bit half a dozen times. A fairly flat point angle worked best.
 

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PTAirco

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Re: Whitman type tubular steel gear

Hi,
Sounds just like the sort of thing I will need for my gear. I have plans for the Sonex, and note that they use titanium rods for their landing gear. I priced this material locally and nearly fell of my chair. 4130 will have to do, thank you very much. I was hoping to use the same dimensions for my project, but since titanium is out of the question, I don't really have much to go on as far as 4130 dimensions are concerned.

Any rules of thumb on this?

My little solo Razorback will be very small and light - estimated MAUW less than 500lbs

Duncan
The steel used is usually 4340, not 4130 and it has to be heat treated to about 220,000 psi to make an effective spring gear. Most places that sell 4130 will also sell 4340.

Rules of thumb don't work too well on this, but EAA has a spreadsheet that helps you do the calculations.
 

Turd Ferguson

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Re: Whitman type tubular steel gear

Hi,
Sounds just like the sort of thing I will need for my gear. I have plans for the Sonex, and note that they use titanium rods for their landing gear. I priced this material locally and nearly fell of my chair. 4130 will have to do, thank you very much. I was hoping to use the same dimensions for my project, but since titanium is out of the question, I don't really have much to go on as far as 4130 dimensions are concerned.

Any rules of thumb on this?
Duncan, from my motorcycle days we sometimes used titanium. I don't recall all the specifics, but we sized parts exactly the same for chromoly and titanium, the difference was titanium clearly had the weight advantage. It's very lightweight, which for an airplane makes it desirable. It was expensive back then as well.
 

PTAirco

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Re: Whitman type tubular steel gear

Duncan, from my motorcycle days we sometimes used titanium. I don't recall all the specifics, but we sized parts exactly the same for chromoly and titanium, the difference was titanium clearly had the weight advantage. It's very lightweight, which for an airplane makes it desirable. It was expensive back then as well.
You can't size it the same as steel if you're using it as a spring gear leg. Titanium's modulus of elasticity is about 16,000,000 as opposed to steel's 29,000,000. Aluminium is about 10,000,000, just to give you an idea of the relative stiffness.
 

wsimpso1

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Re: Whitman type tubular steel gear

I have the EAA spreadsheet if anyone needs it.

Billski
 

PTAirco

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Re: Whitman type tubular steel gear

I have the EAA spreadsheet if anyone needs it.

Billski
Do you also have the accompanying article/sketches? Some of the dimensions asked for are not really well defined. Is "Gear span" from the bend at the axle or from the center line of the tires, for example.

Is "Gear height" from the ground to - where?

I searched the EAA magazine archive, but cannot find an article that accompanies this spreadsheet.
 

wsimpso1

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Re: Whitman type tubular steel gear

I don't have the accompanying articles. And you don't need them either. The version of the spreadsheet I have has diagrams on the sheets with the dimensions defined.

Gear span is lateral distance from gear support to end of spring gear leg. Gear height is the vertical distance from the gear support to the end of the spring gear leg.

Billski
 

PTAirco

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Re: Whitman type tubular steel gear

In that case, can you forward me a copy of what you have, please?
 

wsimpso1

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Re: Whitman type tubular steel gear

PTAirco,

PM me your home email, and I will send it there.

Billski
 

wsimpso1

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Re: Whitman type tubular steel gear

Oh, and can we get the title of this thread changed to "Wittman type", as in Steve Wittman, the guy who invented this gadget. You know, the field at Oshkosh is named after him, and he has airplanes in the Smithsonian.

Billski
 

orion

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Re: Whitman type tubular steel gear

Oops, dyslexic brain function. Sorry about that. I'll try but that might have to be Jake.

(OK, I fixed my original post and header but the "Re." at each post are still the same.)
 
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