Wheel Pants

A lot has happened over the last few months since my last post, and I didn’t have a lot of time to write about it. I will try to catch the blog up in the next few days.

I got quite a ration of crap over the first 6 months of flying Betty. People were always shocked at the audacity of taking Betty around the country without any pants on. So the goal was to get Betty some pants before the AirVenture Cup and Oshkosh. Greg and I were both installing wheel pants on our airplanes, and we pretty much used the method that Wayne Hicks wrote about on his web page. His website is a great resource so I won’t try to recreate the directions here. Go to his site if you are needing the directions. But I will show photos of the installation/process.

First, I should take a step back. I was getting some very uneven wear on the tires. The outboard side of the tires were wearing way too quickly. I did a tire rotation at 45 hours, and by 90 hours on the airplane, the tires needed to be replaced.

After talking with some folks, I decided that I needed to realign the wheel axels. As they were, they had too much camber which caused the excessive wear on the outboard 1/3 of the tires. When I was measuring the axels, I also found that the toe in was different between left and right. I used chalk lines, squares, and lasers to measure this. I should also note that I am changing to the Lamb tires. Which are smaller diameter and wear more quickly. Getting the axel alignment will be crucial to getting decent life out of the tires.

Once the axels were re-alligned, it was time to start on the pants. First is putting the two wheel pant shells per wheel together so they align straight to each other. Then cleco them together.

Then we made full scale drawings to get an idea of where the initial cuts will be for both the tire protrusion and to allow the wheel pants to fit over the gear strut.

Then was the painstaking task of trim, fit, mark, trim, repeat. Taking off a little at a time to get the pants to fit into position without conflict with the tire or gear strut.

Once the wheel pant could fit in place, we used a wheel pant holding jig so that we could get the longitudinal axis aligned with the airplane. During this process the airplane was set at the high speed deck angle on jacks and saw horses. This will give us the lowest drag installation.

From there it was a matter of adding the axel mounting points and the fairing between the gear leg and the wheel pant. We called those the “bonnets.” The axel mounting points were phenolic spacers mounted to the wheel pants. Screws go through those into the axels and a nut plate on the inboard side of the gear leg. The bonnets also have screws and nut plates which prevent the wheel pant from rotating. The bonnets were formed using clay, then waxed for mold release and laid up with fiberglass.

Once the bonnets were laid up we did some work on finishing. First was to add micro to the bonnets. While doing that we also did a one inch area of micro on the wheel pant itself to get rid of the step created by the bonnet.

I was starting to run out of time to get things done before Oshkosh at this point, so we did put primer on, but we skipped the epoxy wipe stage. As such, there are many pin holes and a bit of finishing work still to do, but the installation is airworthy, and looks ok from 30 feet.

It was almost 2 months of work with my limited off time to install the wheel pants, but finally the airplane was back off jacks and ready for flight… almost. I will talk about why it wasn’t quite ready in another post. I am very happy with how the wheel pant installation went, and it really makes a difference in the look of the airplane. Not to mention a huge difference in the performance. It has not scientifically been tested yet, but a short non-scientific test flight showed 14 KTAS increase, lower CHTs, and an additional 150 RPM at WOT.