Thursday, July 7, 2016

Ch 9.5: Axles, Wheels, & Brakes

For wheels and brakes, I selected the Matco Mfg. triple puck brakes...WHL W51 LXT.  The LXT is the extra torque version of the standard triple puck brakes.  I purchased the kit including two wheels, two brake/rotor sets, and two axle sets from Aircraft Spruce and seemed to get a little better deal, including free shipping due to the amount, than buying direct from Matco.

Bullseye - Checking
the centerline
I had to move the fuselage to a new location so I re-leveled and re-aligned the fuselage per plans.  In fact I rechecked it multiple times throughout the ordeal.  I was convinced my center-line was accurate, but I was never quite sure the perpendicular line marking the leading edge of the gear strut was accurate. Ensuring it is in fact perpendicular is important because the error grows the farther out from the center-line you get.  I finally decided it was as close as I thought I could get it, and using plumb bobs, the leading edges of the strut seemed to be within .05" tolerance.  I also set up paper on the far wall to project the center-line and axle positions for adjusting the required toe-in.

Checking each side for accurate
axle center and height
Next I located the axle center points based on the plumb bobs at the appropriate FS mark, and using 42" as the distance from the longeron to the axle centers.

Bernie's Template
BID Wrap Curing
I followed the toe-in alignment procedure in the plans but used a laser level to project points on the far wall approximately 18ft away.  I closely followed Bernie Siu's website description to ensure my toe-in calculations were correct.  Bernie mentioned the possible error when using a laser...something I wouldn't have thought of.  After checking, my laser did in fact have a small error.

Next, I used axle templates from Bernie Siu to locate the mounting holes and outline of the leg cutting I would have to do. Then I performed the BID wrap of the gear leg area.

Port Flox Pad
Starboard Flox Pad
Once the toe-in point was located, I used a 1x scrap of wood and a tension clamp to form a nice flat flox pad for mounting the axles.

Backing Plate
Cutting the Strut
Fit Check
I originally drilled the holes before I fab'd the flox pad...I don't recommend doing this.  Since the strut is curved, it's difficult to keep it at the right toe-in location while drilling...I ended up with a hole off angle and had to fill and re-drill it once the flox pads were on.  I.clamped the axle in place when I drilled the holes and inserted the bolts after each hole to help hold the axle straight and help me drill straight...something hard to do with the long bit you have to use.  I then fabricated the backing plate, round vs square, and floxed them in place.

Cut to Shape
Mounting holes drilled
Now that the wheels and brakes are ready to mount, I again turned to Bernie for his heat shield templates.  These were fairly simple to make...a couple of hrs work...and came out nicely I think.  I used some Mother's aluminum polish from your local Auto Zone aircraft supply house to put a high gloss finish on them to reflect radiant heat.  Lastly, they have to be bent per Bernie's template to clear the brake calipers.

Polished but not yet bent to shape
I mounted the axles, tires & wheels, heat shields, and brakes, torqued everything to specs...and Ta Daaa!  After a few other clean up items while it was inverted, she's was now ready to flip back over. A Big thanks to Bernie Siu for his excellent builders log and allowing me the use of his axle and heat shield templates.

Onward to the gear leg fairings,

Port Side - head on
Note the heat shield bends
Ready to roll...once I get it turned over of course.

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