NC12350   Monocoupe 110

Landing gear, wheels and brakes

The project came with two landing gear legs, which sort of fit the fuselage attach points, but I had no history of these legs and in light of recent gear leg failures on several other Monocoupes, I opted to have a new set of  gear legs made.  NC12350 was delivered with the Type F Racing Landing gear and we fabricated a new set per the original Monocoupe drawing.  I am also upgrading to Cleveland wheels and brakes.

New main gear legs, fabricated from 1.5” OD, 0.095 wall thickness 4130 tube, mandrel bent to specs on Monocoupe drawing, new solid axles, etc ready to jig in assembly with the fuselage.  At this point, the reinforcement patch, on the inside of the “knee” has been welded in place, along with the tabs for the tie rods.

 

I made a steel jig to clamp the gear legs in position, dropped plumb lines front and back, drew a center line down the shop floor, measured diagonals front and back to within 1/32”, leveled everything up.  Next step was to cut and fit the rear gear leg, along with the attach bushings.  The photos below show everything in place and ready to tack weld.

 

I fabricated a new tail wheel from the Monocoupe drawing. Cut out patterns from a copy of the drawing, lay it out on steel plate for cutting.  Instead of the caster commonly used on these tailwheels, I’m using the 4” solid rubber wheel used on the Aviat Pitts Special.  So, I did a test fit and bend of the side plates out of aluminum, due to ease of cutting and bending for the prototype.  Once I was happy with the results, everything was cut out.

 

The I took all the pieces over to Shawn Jarrell at Jarrell Custom Aero Fabrication in Scottsdale for final welding.  Sand blast and primed the assembly looks great and I think it is going to work just fine.

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Landing gear, wheels and brakes (cont.)

The attach bushing is a piece of 3/4” OD, 0.065, 4130 tubing, which after welding gets reamed to accept a 5/8” OD, 1/2” ID bushing.  The attach bushing gets covered with a 0.095” x 1-3/8” 4130 strap.  As you can see in the cut out from the drawing, on the left, this strap has to wrap around the bushing.  Here is how I made this piece.  Started with a piece of 4130 strap, 1-1/2” wide, which is a little over-width, about 11.5” long.   The bushing is not perpendicular to the gear leg, so as the strap wraps around the bushing, it wants to wander off center.  So, the extra width allows me to correct for that.  Below left, do the first bend on the brake.  Next, move to a little jig, comprised of a 1/8” steel plate and a piece of 3/4” solid 4130, strapped down to the table.  Heat the strap up and start to wrap it around the 3/4” form.

Finish wrapping the strap around the solid form using a big ole chisel ground to have a nice round radius, all done by heat and hand pressure on the chisel, and big leather gloves!  Next, clamp the strap over the bushing, which has been tack welded in place.  The heat the strap down over the shape of the gear leg.  Next step is a lot of grinding on the strap to shape it around the bushing, trim and round the ends, etc.  Final step is to heat and bend the strap to the radius of the gear leg.

Strap in place, over the attach bushing, rear attach bushine welded in place with reinforcement strap welded in place.  Next step is to triple check final alignment and tack weld the “V” at the bottom.