This week I'm going to a talk about the modifications we've made to the tail section of the streamliner. Cumulatively, they represent the largest external change to the Challenger II, so we've been approaching them cautiously.
Although we've been updating the car for over a year, almost all of the changes have been beneath the hood. The body is still old school, and we want to maintain the integrity of the original while making sure that the final product is fast and safe.
The Challenger II originally deployed its parachutes by ejecting a fiberglass subsection of the rear wing with compressed gas. That would never fly under current safety regulations, so our aero man Tim Gibson devised a plan to extend the original tail section of the car to accommodate integrated parachute tubes.
This has two advantages. First, it moves the car's center of pressure away from it's center of gravity, which improves overall stability in adverse (windy) conditions. This is especially important to me after a tumble I took a few years ago while we were running the world's fastest Ford Mustang. Second, the larger undertray will take advantage of the air moving beneath the streamliner to increase net downforce without a significant increase in drag. That's a rare win-win.
The reason we've been able to accomplish this without dramatically changing the exterior of the car comes down to improvements in parachute technology. In 1968, the Challenger II required chutes with 12ft blossoms. Today, we can get identical stopping power with 4ft chutes. We've performed an extensive retrofit to support the additional tail length – approximately three feet – which has involved a new substructure, as well as more mundane things like new cable mounts and brackets, We've also added a fixed Replay XD camera, which will allow us to visually monitor parachute deployment.
Next week we'll take about body shape and how we're blending it with the bottom of the streamliner. Thanks for following along!