Wittman type tubular steel gear

Discussion in 'Hangar Flying' started by orion, Mar 25, 2009.

Help Support HomeBuiltAirplanes Forum by donating:

  1. Mar 25, 2009 #1

    orion

    orion

    orion

    Well-Known Member

    Joined:
    Mar 3, 2003
    Messages:
    5,800
    Likes Received:
    135
    Location:
    Western Washington
    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.
     
    Last edited: Apr 21, 2009
  2. Mar 25, 2009 #2

    DaveK

    DaveK

    DaveK

    Well-Known Member

    Joined:
    Apr 22, 2007
    Messages:
    343
    Likes Received:
    17
    Location:
    Northern California
    Re: Whitman type tubular steel gear

    I think Harmon Lange's business is who you are looking for. Langair Machining, Inc.

    Dave
     
  3. Mar 26, 2009 #3

    orion

    orion

    orion

    Well-Known Member

    Joined:
    Mar 3, 2003
    Messages:
    5,800
    Likes Received:
    135
    Location:
    Western Washington
    Re: Whitman type tubular steel gear

    That's the one - thanks.
     
  4. Apr 14, 2009 #4

    Turd Ferguson

    Turd Ferguson

    Turd Ferguson

    Well-Known Member

    Joined:
    Mar 14, 2008
    Messages:
    4,914
    Likes Received:
    1,816
    Location:
    Upper midwest in a house
    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.
     
  5. Apr 14, 2009 #5

    rtfm

    rtfm

    rtfm

    Well-Known Member

    Joined:
    Jan 3, 2008
    Messages:
    3,194
    Likes Received:
    573
    Location:
    Brisbane, Australia
    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
     
  6. Apr 14, 2009 #6

    PTAirco

    PTAirco

    PTAirco

    Well-Known Member

    Joined:
    Sep 21, 2003
    Messages:
    3,501
    Likes Received:
    1,013
    Location:
    Corona CA
    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.
     

    Attached Files:

  7. Apr 14, 2009 #7

    PTAirco

    PTAirco

    PTAirco

    Well-Known Member

    Joined:
    Sep 21, 2003
    Messages:
    3,501
    Likes Received:
    1,013
    Location:
    Corona CA
    Re: Whitman type tubular steel gear

    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.
     
  8. Apr 14, 2009 #8

    Turd Ferguson

    Turd Ferguson

    Turd Ferguson

    Well-Known Member

    Joined:
    Mar 14, 2008
    Messages:
    4,914
    Likes Received:
    1,816
    Location:
    Upper midwest in a house
    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.
     
  9. Apr 14, 2009 #9

    PTAirco

    PTAirco

    PTAirco

    Well-Known Member

    Joined:
    Sep 21, 2003
    Messages:
    3,501
    Likes Received:
    1,013
    Location:
    Corona CA
    Re: Whitman type tubular steel gear

    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.
     
  10. Apr 20, 2009 #10

    wsimpso1

    wsimpso1

    wsimpso1

    Super Moderator Staff Member

    Joined:
    Oct 19, 2003
    Messages:
    6,148
    Likes Received:
    3,455
    Location:
    Saline Michigan
    Re: Whitman type tubular steel gear

    I have the EAA spreadsheet if anyone needs it.

    Billski
     
  11. Apr 20, 2009 #11

    PTAirco

    PTAirco

    PTAirco

    Well-Known Member

    Joined:
    Sep 21, 2003
    Messages:
    3,501
    Likes Received:
    1,013
    Location:
    Corona CA
    Re: Whitman type tubular steel gear

    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.
     
  12. Apr 21, 2009 #12

    wsimpso1

    wsimpso1

    wsimpso1

    Super Moderator Staff Member

    Joined:
    Oct 19, 2003
    Messages:
    6,148
    Likes Received:
    3,455
    Location:
    Saline Michigan
    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
     
  13. Apr 21, 2009 #13

    PTAirco

    PTAirco

    PTAirco

    Well-Known Member

    Joined:
    Sep 21, 2003
    Messages:
    3,501
    Likes Received:
    1,013
    Location:
    Corona CA
    Re: Whitman type tubular steel gear

    In that case, can you forward me a copy of what you have, please?
     
  14. Apr 21, 2009 #14

    wsimpso1

    wsimpso1

    wsimpso1

    Super Moderator Staff Member

    Joined:
    Oct 19, 2003
    Messages:
    6,148
    Likes Received:
    3,455
    Location:
    Saline Michigan
    Re: Whitman type tubular steel gear

    PTAirco,

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

    Billski
     
  15. Apr 21, 2009 #15

    wsimpso1

    wsimpso1

    wsimpso1

    Super Moderator Staff Member

    Joined:
    Oct 19, 2003
    Messages:
    6,148
    Likes Received:
    3,455
    Location:
    Saline Michigan
    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
     
  16. Apr 21, 2009 #16

    orion

    orion

    orion

    Well-Known Member

    Joined:
    Mar 3, 2003
    Messages:
    5,800
    Likes Received:
    135
    Location:
    Western Washington
    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.)
     
  17. Apr 22, 2009 #17

    wsimpso1

    wsimpso1

    wsimpso1

    Super Moderator Staff Member

    Joined:
    Oct 19, 2003
    Messages:
    6,148
    Likes Received:
    3,455
    Location:
    Saline Michigan
    I feel so much better now!
     

Share This Page

Group Builder
arrow_white