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RACER.com Diary 13: 400mph in a Piston Powered Car

How hard is it to go over 400 MPH in a piston powered car? Well, since 1947, only 11 people have managed to do it. That is, for reference, one less than the number of people who have walked on the moon. But things are heating up. For 52 years, the overall record grew by only 8 MPH. Last year, the Speed Demon exceeded that mark by almost a factor of three, and bumped it by a whole 22 MPH. The Treit & Davenport car, a perennial favorite, is running for the first time after 13 years of development. This year, Bonneville will host the largest gathering of 400 MPH+ streamliners in history, and will proffer the most exciting series of salt events in decades. 

Most of those vehicles will be competing in different classes, but to my way of thinking, there is only one real record, and that belongs to the fastest overall piston powered car. There isn’t a specific name for that, but I’ve taken to calling it The World’s Fastest Hot Rod. There are somewhere between 6-8 vehicles with a shot at that title, and I believe that the Challenger II is one of them. 

With that said, jumping in the cockpit and mashing the gas tomorrow would be foolish, no matter how badly I want it. Most of the other LSR cars I mentioned were running for years before they cracked the 400 MPH barrier, let alone challenged the record. Sneaking up on the big number has been the modus operandi of the most successful attempts. The team here at THOMPSONLSR has been working like crazy trying to make Speed Week in August. Right now, that date is looking unrealistic given the amount of testing I want to do. There isn’t any room for mistakes at these speeds, so we’ll be trying for runs at the World Finals in October. My current goal for this year, frustrating as it is, will be to make sure that all the functions and safety mechanisms are up to snuff before I gas it. 

See you next week.

RACER.com Diary 12: Ones and Zeros

Throughout the update, we’ve taken pains to ensure that the Challenger II stays old school. But we’re traditionalists, not Luddites. Electronic systems are a major component of contemporary racing, and our team has embraced that. Leading this effort is Donny Cummins of RacePac, a really smart guy with a proven product. He’s been collaborating with A/Fuel Dragster guru Jerry Darrian to come up with our engine monitoring system. 

As those of you who’ve been following us for a while know, the Challenger II is a four-wheel drive vehicle with dual engines. The power plants interface with each other via Hadley Boxes, which are basically bespoke gearboxes that mechanically balance output. Given that the two engines are being built of identical parts by the same group of people, they should be perfect doppelgängers. But they’re not, and that’s where the electronics come into play. Donny’s products allow us to measure twenty different variables simultaneously and identify even minute inconsistencies. That data helps us maintain uniformity during the run, and reduces the load on the Hadley Boxes, which rely on difficult to repair metal gears rather than easily rebootable ones and zeros. 

We also have the ability to monitor the status of the chassis. This is absolutely essential, as its characteristics will change markedly over the course of the run. For instance, at the starting line, the nose of the car will contain nearly sixty gallons of nitro blend. By the five mile mark, most of that volume will be gone, reducing the vehicle’s curb weight by over five hundred pounds. If everything is going well, we’ll be going over 400 mph at that point, every yard of which will cost us front traction in the form of reduced weight. If we don’t properly compensate for that with aerodynamic down force, we’ll be in a world of trouble. The electronic monitoring, in combination with extensive testing, will allow us to fine tune the adjustments necessary to predict changes in the car’s attitude and lift over the course of the run. 

In short, although Donny may not have been around in 1968, we’re very glad that he’s here now. As the struggle for sponsorship continues, we’ve been exploring a different approach that we’ll discuss in the next article. See you then!

RACER.com Diary 11: Old School Aluminum

The design and engineering of the original Challenger II was a close collaboration between my dad’s crew of hand-picked drag racing guys and Ford’s in house Kar Kraft team. The point man at Kar Kraft was Ed Hull, who you might recognize from some of Ford’s more spectacular projects, including the GT40 Mark IV. The two groups had gigawatts of brainpower, but they also had a lot of practical experience, which lead directly to some of the Challenger II’s more superficially confusing features, including the segmented aluminum skin. 

The credit for that goes to Nye Frank (a hero of mine), who had worked on Craig Breedlove’s Spirit of America, and was constantly frustrated by the need to remove large portions of body work in order to perform simple maintenance or repairs. The subdivided architecture of the Challenger II means that almost all areas can be accessed quickly and independently by popping a few Dzus buttons, an advantage that we’re counting on to make the FIA’s mandated one hour turnaround. To see it in action, have a look at the video underneath this article. 

I’m often asked if the sheet metal work is original, and the answer is an emphatic yes. The body was crafted by Tom Jobe and Nye Frank over forty-five years ago, and is an absolute work of art. The only changes so far have been the relocation of an air intake and a 32 inch extension to the tail section on the recommendation of our aerodynamicist Tim Gibson. Matching the existing work meant finding old school talent, and we were fortunate to locate Terry Hegman, who is one of the world’s last truly gifted aluminum men. As a fellow fabricator, seeing his work each week leaves me green with envy. 

When you look at the flowing lines of the streamliner, it’s impossible not to see it as a thing of beauty. From above, it looks like it’s breaking records standing still. If I were building a new car from scratch, there’s no question that I’d be using carbon fiber instead of aluminum, but I really don’t think I’d get the same overwhelming sense of craftsmanship. When I look at the Challenger II, I’m reminded a little bit of Apollo 11, which launched about a year after the streamliner’s rained out test run. It’s got a real sense of adventure about it, and I like it that way. 

 

RACER.com Diary 10: Making the Turn

A great deal of effort has gone into making sure that the Challenger II travels in a straight line. If you happen to see it changing direction quickly, cover your eyes, because what happens next isn’t going to be pretty. Although the car’s aerodynamic properties should do most of the work of keeping it level, an inordinate amount of attention has also gone into the steering. We’ve reserved enough packaging space to provide the streamliner with up to five degrees of back and forth maneuverability, but that number will probably be artificially restricted to a lower amount after our initial test runs. At Bonneville, slow movement is safe movement, and we’ve engineered the car to respect that.

Of course, some steering is necessary to get the liner off the track at the end of the run.  This is especially relevant during Speed Week and other SCTA/BNI events where many cars participate in quick succession. Fortunately, when you’re traveling at very high speeds, it doesn’t take long to cover the lateral distance to the recovery area.  And for the events mentioned above, that’s really all it takes. If we’re fortunate enough to get a record, we’ll load the vehicle onto the trailer and head to impound. We won’t have to make the return run until the next morning, which gives us a bit of breathing room and ample time to prepare. If we don’t make it, we’ll head back to the pits, perform adjustments, and try again.

Unfortunately, FIA runs aren’t that simple. In order to capture that record, we need to turn the car around and backup our previous run within one hour. In our case, that means adding sixty gallons of specially prepared fuel, changing the oil in both dry sump tanks, switching out 32 spark plugs, adjusting both engines, examining the tires, and quickly but thoroughly performing checks on all the streamliner’s systems. We also have to do something that we’ve intentionally made very difficult, which is turn the car around. With five degrees of steering, making a loop in the Challenger II would require almost a mile of runway. At 5500 pounds, it’s too heavy to easily move, and loading it onto the trailer in order to reverse it requires time that we probably won’t have. 

Luckily, the very smart Bob Skinner came up with an ingenious solution to this problem more than 45 years ago. Nestled inside the body of the Challenger II are four huge air jacks. When it’s time to turn the car around, a simple application of air pressure causes them to deploy downwards, elevating the entire streamliner six inches off of the ground. Next, two crew members will slide a purpose built lazy Susan underneath and rotate the vehicle 180 degrees. Once it’s facing the right direction, we’ll reverse the jacks and gently lower the car back to the salt. In testing, this takes a mere five minutes and allows most of the crew to continue working throughout.

RACER.com Diary 9: Precious Cargo

As we get closer to the streamliner’s first test runs, we’ve had to devote some time to the logistical challenges of transporting such an unusual vehicle. The salt flats are a unique environment that requires a fair amount of esoteric planning, especially when it comes to the best way to move the car around the speedway. The unexpected softness of the salt, especially at the north end where vehicle recovery takes place, has been causing problems for people since at least the 1800‘s, when the Donner Party got stuck indefinitely and ended up eating each other. We’re more likely to encounter a string of tow trucks than a gaggle of cannibals, but we’re professionals, so we decided to take the problem seriously anyway. 

The Challenger II has grown a little bit lately, and is now just over 32 feet long. The ground clearance is a meager two inches, so the most immediate problem was getting the car off of the trailer without scraping the bottom or damaging the strake. We also wanted to minimize weight if possible, as the streamliner itself is already relatively heavy at 5500 pounds. That particular concern led us to abandon the idea of an enclosed trailer (which was my preference), and sent us on a hunt for the best already existing uncovered trailer we could find.

That eventually led us to Seth Hammon, who in my opinion has the nicest rig on the salt. Using his trailer as a baseline, the very talented John Pollorena has been building us a modified version specifically for the Challenger II. The first thing he did was narrow it by 10 inches. This will allow us to comfortably work on the car without having to remove it from its transporter, and mimics the height of the frame fixture we use at the shop. Another unusual feature is the axels, which are on arms welded to the side of the main rails instead of under the framework. This allows a system of air bags (similar to what you’d find in a semi) to slowly lower the bed of the trailer flat to the salt. From this position, the ramps can deploy at a 2 degree angle over a span of thirty feet, giving us a comfortable .5 inch clearance impediment for loading. There are a few other modifications as well, including a toolbox mounted at the nose and an integrated 100 gallon water tank over the fifth wheel for washing off excess salt. 

Things are coming along! I hope you’re enjoying the updates. See you next week.