This was an exciting month. A lot of the individual projects that we've been working on independently are finally starting to come together. Plus, we've taken delivery of the second engine. Twin monsters.
Stay up-to-date with our progress.
This month we take you into the cockpit, onto the trailer, and directly in front of the nose. We also show off some of our newly finished front end parts. Did you know that virtually all of our photos are taken by the talented Holly Martin? You should visit her new website here: www.metalandspeed.com
One of the biggest stumbling blocks on a car like the Challenger II is maintaining aerodynamic slipperiness while simultaneously providing the engines with sufficient air to properly ignite the fuel. To feed the front engine, we have a center-mounted flush duct that sits on top of the vehicle, roughly where the hood would be on a normal car. When the car is in motion, it directs plenty of air to the front engine with minimal aerodynamic impact.
The rear engine is more challenging because it is situated behind the driver’s canopy. As air travels over the canopy, it is directed upwards, creating a null space in the area a top mounted intake would normally be located. To get around that problem, my dad and his crew added NACA ducts to both sides of the vehicle adjacent to the the rear engine. But to be frank, they were one of the few parts of the original vehicle that didn’t work well. The ducts directed oncoming air into a squirrel cage, where it had to spin 180 degrees before reaching the throttle bodies. The air tended to stall within the cage, which eventually necessitated the addition of small ears to the NACA ducts. This improved their function, but had significant aerodynamic disadvantages.
My original plan was to replace the NACA ducts with a rear air scoop, which is the most common solution utilized by other streamliners. I mocked it up in cardboard, but when Tim Gibson, my engineer and aerodynamicist, saw the result he deemed it aerodynamically unacceptable. Tim’s a ridiculously smart guy, so after gathering and calculating all of the necessary data, he presented me with a solution that provided sufficient air intake without significant aerodynamic disadvantages.
His solution was a set of side-mounted straight intakes with specific veins that funnel air directly to the throttle bodies. While this superficially resembles the NACA duct solution, it is simpler, more efficient, and actually works. The master metal shaper Terry Hegman took Tim’s drawings and spent the next three weeks hand shaping the intakes into the car’s aluminum skin. I’m glad we have Terry, because there simply aren’t that many people who can do that anymore. The end result, as you can see in the pictures, is gorgeous.
See you next week.
We have amazing fans, and they send us a lot of great stuff. We repost most of it to our Facebook Page, but Facebook can be confusing, and we've received several requests to make it more easily accessible. Starting today, we'll be posting PDF copies of old Mickey Thompson articles here, where they are easy to access and read. Please note, a lot of these files are REALLY BIG, so they may take a while to download, especially on mobile devices. For that reason, we've appended the author bylines with the file sizes. Enjoy.Read More
THOMPSONLSR is more than excited to announce that AIRAID® will be joining our team as a sponsor. AIRAID® designs and manufactures the finest premium air filters, throttle body spacers, and cold air intake systems in the industry. In our articles and blog posts we talk a lot about our insistence on using (or building) only the best and most reliable parts for the Challenger II. AIRAID® products were always our first choice when they were available for our needs. Having them as a sponsor is just icing on the cake. Thanks AIRAID®, and welcome to the team!
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This month's update is all about air intakes, drive shafts, parachute tubes, and the never ending work on the front end. If you're curious about the changes we've made, our upcoming RACER.com Diary will go into a little bit more detail about the modifications.
I just got back from Speed Week, so I thought I’d take a break from talking about the changes we’ve made to the car and elaborate a little bit on how the Challenger II project got started back in 1968.
The catalyst, believe it or not, was a Mustang. Ford, then under the control of a newly appointed Bunkie Knudsen, was looking for a way to promote the new Mach I. Bunkie had worked together with Mickey while he was heading up Pontiac, and they started bouncing marketing ideas off of each other. Eventually, they came up with a campaign that would emphasize not only the performance of the Mach I, but Ford’s new 427 SOHC engine as well.
To promote the Mustangs, my dad and Danny Ongais took three of the new models up to Bonneville with the intention of breaking as many new and existing speed and endurance records as possible. It ended up being a tremendous success, and they were able to deliver more than 250 records to the Ford marketing department. Simultaneously, the new 427 was being promoted as the power plant in both Mickey’s Funny Cars and the new Challenger II.
In exchange for assisting in Ford’s Mustang and Funny Car efforts, M/T got significant support for his speed record project. Ford and Autolite (which was owned by Ford at the time) agreed to be the primary financial sponsors, but they also gave Mickey access to their skunk works Kar Kraft division, which helped to design the car. My dad’s liaison at Kar Kraft was Ed Hull, who was also involved with the creation of the GT40 Mark IV.
Once Ed’s team had finished the engineering, Mickey recruited a handful of California’s most talented hot rodders to complete the actual construction. He somehow managed to get names like Frank, Jobe, Epperly, and Buttera all on the same crew, and they were able to finish the car in an absolutely astonishing 6 months (I’ve been working on the restoration for two years). After that, it was off to Bonneville.
I hope you enjoyed learning a bit more about the history of the car. See you next week.
I’ll be at the salt this week, but the Challenger II will not be with me. My team and I have been beating ourselves to death trying to finish, but the simple fact is that the streamliner is not done, and I’m unwilling to compromise on any aspect of a vehicle intended to go 450mph with me sitting in it. Doing it right takes precedence over getting it done, which is frustrating but necessary.
The good news is that we’ve most likely found a place where we can test within Orange County, which will save us quite a bit of time and a not insignificant amount of money. We’re a couple months off, but the location will allow us to perform some slow speed tests around 170mph, which is adequate for our aero calculations and will let us function test the new drive train without placing too much stress on it.
Work continues of course, and we’re really making progress on the challenging stuff. Lou is finishing off the front spindles, which will then proceed to heat treat and final machining. The side bells that are bolted to the rear end are now finished. They’re fabricated from 17 individual pieces of hand formed 4130 chromoly, and were welded with high quality heat treatable rod. The welds took over 3.5 hours per side, but I was really pleased with the results. We magna fluxed all of the parts before sending them off for heat treatment, and they ended up perfect.
SK Specialties is just finishing the final machining on the front steering, which was far and away the most difficult modification we made to the streamliner. The front axel, inner and outer u-joints, driver plates and associated parts are all made out of wicked 300M alloy and will be out of heat treat by the time I return from Bonneville. They’ll join the transmission shafts (which are being triple splined) and drive hubs on the way to final grind.
Overall, I’m pleased with our progress and the quality of work we are doing. We’re still raising money via Kickstarter, so if you’re interested, pleased head to thompsonlsr.com and click on the link. See you on the salt!
In order to promote our Kickstarter campaign, we’ve been doing a lot more press work. For the more technically oriented publications, that means explaining in detail the changes we’ve made to the car. When we get to talking about the rear ends, we inevitably get asked the same question. “Did you say Hadley Box? What’s a Hadley Box?”
That’s a reasonable question. The Challenger II has two engines and is four wheel drive. That means it has duplicated drive trains that are mirror copies of each other. In order to achieve this, we actually had to mount the front engine backwards in the streamliner. The drive trains each have three components--a B&J three speed transmission, a Hadley Box, and a custom built rear end with quick change gears. The functions of the transmission and rear end are obvious. The Hadley Box is a little unusual.
Simply put, the Hadley Boxes mechanically connect the front and rear engines via a three piece drive shaft. The shafts coming off of the engines are mounted at equal but opposite 2.5 degree angles. The middle shaft is perfectly level. This connection allows the engines to remained synchronized during our runs.
Strictly speaking, this system is not mandatory. It’s certainly possible to connect both engines independently to the gas pedal. The Hadley Boxes are a safety feature that we’ve devised in order to keep the engines from running away from each other. For example, should the front engine fail during my run, under normal circumstances the rear engine would keep pushing, potentially resulting in a spin and a crash. With the Hadley boxes, the rear engine will mechanically know that the front engine is locked, the clutch will automatically drop it into neutral, and the rear engine will continue to power both sets of wheels independently to a safe stop.
That’s an extreme example, but the principle of communication holds true in less dire circumstances, including wheel slip, which will greatly impact our ability to make traction. As for the name, the Hadley Boxes are christened after Dave Hadley of SK Specialties, the only person crazy enough to build them.
Thanks for following along. See you next week.