Mounting the landing gear in an I beam wing

[Airacobra]

Looking at some ideas that you guys use to mount the landing gear in an I beam wing. I have seen J- bolts, landing gear clips and I think I have seen Werwages video where he uses a soft wire to attach the gear to the spar. Any ideas are appreciated.

[Ken Culbertson]

Looking at some ideas that you guys use to mount the landing gear in an I beam wing. I have seen J- bolts, landing gear clips and I think I have seen Werwages video where he uses a soft wire to attach the gear to the spar. Any ideas are appreciated.

I built numerous tricycle I.-Beam wings in the late 60's.  I used two 1/8" plywood doublers over a 1/8" spruce center spar capped by 3/8 x 3/32 spruce cap. Torsion landing gear and floating bellcrank sandwiched between the outer plys with cutouts in the spruce for the wire. 1/4" sq. doubler behind the gear wire. No screws or clamps.  Never had one fail.  Not much of a fan of putting holes in an I-beam.  They are supposed to flex and holes hinder that.

If it is a tail dragger I would use Ty's method and if I were to build another one today I would probably use some form of removable so I could easily switch from small covered concrete wheels to larger open grass ones.

Ken

Ken

[Dave Hull]

Keith,

I am currently building one. My thought was to at least build one according to the classical methods before I started with the mods--although I was very tempted to follow Ty's approach. My gear is done, and I'm happy with it. Ready to start installing ribs when I get some time. Didn't have any problems so far. I was actually more worried about the extra hassle of covering and finishing with the gear in place. Ty didn't mention it, but that is a really big advantage of his method in my opinion.

I used hobby shop J-bolts, but put them in a wire bender and bent them a full 180 degrees. Then I trimmed them so they wouldn't bottom out on the spar web. The way it finally went together, I was able to keep the threaded portion of the bolt in tension, and avoid bending loads.

Don't worry too much about putting bolt holes for the gear thru the spar. All of the flight the bending loads in the spar are at the top and bottom surfaces and the center pretty much only carries shear. Same with wing torsional loads. It's the covering that has to carry the most load, not the spar web. The bigger issue is avoiding excessive landing loads on the spar. Land smooth.

I can't post pictures here, but if you want I can send via iphone. PM me your number if you think it would help you.

Good luck with your project!

Dave

[EddyR]

 The gear should not be mounted until  the ribs are in place other wise the gear is in the way when the wing is turned over. Building a I/Beam straight requires the wing be flat on the building surface. The slotted hardwood RC type mount worked best for me in all my builds for the last 20 years. I mounted the hardwood against the spar front and that way the gear is in the same spot as the plans show.  Some of Billys I/Beams had the gear on a plywood plate that went from the leading edge to the spar,USA1.
Ed