Stay up-to-date with our progress. Diary 7: Engineering Agony

The Challenger II was built in five months. I’ve been working on it full time for almost two years, and it’s the hardest thing I’ve ever done. The problem, I suspect, is that my dad hired a team of geniuses to design it, and another team of geniuses to build it. I’m just a race car driver that likes to weld. The engineering and packaging complexity is so omnipresent that a 1969 magazine article called it “on par with a lunar module.” Most days, that feels about right. 

When we run into problems, they don’t occur, they cascade. I’ve already had a couple of smart guys give-up on the project because of the difficulty. Very high speed racing is such an esoteric undertaking that a lot of the equipment and expertise we need is outside of the automotive community. In the past six months I’ve spent more time researching material properties and manufacturing technology than I have building stuff. But I’ve learned a lot, and I’ve found a few invaluable guys to help me overcome the hurdles.

Tim Gibson is our aero engineer, and he’s been tackling the front steering, which is the most complicated aspect of the liner in terms of packaging. He has a little under 35 inches to work with, which is the width of the car. Sitting directly in the center of that space is a 12.5 inch rear end (not a front end--we have the forward engine facing backwards), which leaves him with 11.25 inches per side. In that space he has to fit a spindle with a split king pin, a brake caliper, a brake rotor, a u-joint, a wheel, and a tire. After he’s done all that, he has to make sure that there is enough space left over for 5 degrees of steering in either direction. 

After Tim figured out how to draw the front end, we had to determine how to build it and where to source the materials. We knew we needed to assemble the u-joint out of a specially heat-treated maraging steel. Unfortunately, the u-joint is made up of two splined yokes that fit together precisely. If we tried to cut the splines after the heat-treatment, the metal would be too hard. If we cut them before, the slight warping caused by the process would ruin the perfect fit. We needed something that could cut extremely hard material to very close tolerances. The answer, it turned out, was something invented in the 1940s called electrical discharge machining. I’d tell you more about it, but according to Wikipedia “it appears that the material removal mechanism in EDM is not yet well understood.” So there. 

What matters to me is that it works, and it brings us one step closer to the salt. Thanks for following along. See you next week.