After splitting the pant halves that were epoxied up last night, I built a jig to help me align the wheel pants to the plane. This jig will hold the pant exactly where I want it, and is a much more precise and stable way to do it compared to just using a plywood to balance the pant on. The pants will be held to the jig with #40 drill bits, which are drilled thru the pants at the centerpoint locations that were marked last night. I also added little adjustable feet to the jig for making fine adjustments.
The first step is getting the rear half of the pant lined up and trimmed to fit around the gear leg. A spacer is taped to the top of the tire to provide the needed interior clearance. Once the pant clears the gear leg, you make sure the pant is aligned to the wheel in the “roll” orientation and that the opening on the bottom is centered around the wheel, and then match drill the pant to the axle extension.
***Note from the future. I used a slightly different method for the “pitch” angle alignment on the nose wheel pants that worked really well. The basic idea is to align the pant perfectly in the roll orientation on a bench top using squares, then simply connecting the front and rear center points with a laserplane, and marking that line with a sharpie. You now have a perfectly level line for alignment.
Next I attached the front pant half and with a little back and forth adjusting with a ruler, I got the pant leveled. Once it was pretty close to level, I drilled thru the jig to hold everything in place. Then is was adjusted again, this time with finer precision that the jig allowed for.
After getting the “roll” orientation and “pitch” orientation dialed in, I needed to set the “yaw” orientation. To do that, I had previously marked the aircraft centerline on the concrete below the plane, using a plumb laser. Now, I extended a parallel offset centerline closer to the wheel to make measuring easier.
I then used another laser to mark a vertical line down the jig from the drill bit to the ground. In order to get an accurate measurement, I added little aluminum tabs to the bottom of the jig that would allow me to draw this vertical line all the way down to the floor, so I could get a reading off of a ruler laying flat on the floor.
As I was nailing these little pieces of aluminum to the jig, I managed to smash the nail on my left pointer finger with the hammer. It didn’t feel good. And as a result, I don’t have any good pictures of what I was working, as I was too busy inventing new curse words.
These are the only pictures I got:
Here is a picture from the future that shows the aluminum tab I described. You can see a mark on the bottom of the tab that represents a spot perfectly below the centerline of the wheel pant.