TIG Welding for 300 Miles Per Hour - Larsen Motorsports Fires Up Crowds & Its Welder
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Driver Elaine Larsen of Larsen Motorsports ignites 6,000 lbs. of thrust to energize the crowd and the afterburner of Embry-Riddle’s Jet Dragster.
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In drag racing, the jet dragster class is an elite group of exhibition vehicles that can accelerate from 0 to 300 miles per hour down a quarter-mile drag strip in under 5 seconds. The car and driver represent the expertise of a dedicated team of mechanics, engineers and fabricators. The rush of 5.5Gs and adrenaline kicks in almost as fast as the afterburner ignites. Having trust in your team and the car is important to put on a safe and entertaining show. This amazing spectacle of speed and mechanical beauty is something that simply needs to be experienced in person.
Drag racing is a way of life for Chris and Elaine Larsen, a husband and wife team who formed Larsen Motorsports of Haines City, Florida. Chris is the crew chief and Elaine the driver for the Miss Ta Fire and Embry-Riddle Aeronautic University jet dragsters. Regarded as one of the nation’s leaders in turbine-powered race vehicles, they are the number-one-booked exhibition jet dragster team in North America. Appearances at NASCAR and the National Mustang Racing Associations World Finals topped off their sold-out 2007 season. These automotive enthusiast groups recognize Larsen Motorsports for its ability to consistently deliver safe entertainment on the track, and there is a good reason why. They are also the only 100-percent self-contained jet racing team, meaning they do not need to outsource anything—including the welding.
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The Embry-Riddle jet dragster sits awaiting a repair to the afterburner shell.
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Larsen Motorsports relies on the portability of the Maxstar® 150 STH Stick/TIG welder to perform routine maintenance and repairs on its jet cars in the shop and at the track. Portable welding equipment such as the Maxstar 150 series make repairs on the road easier than ever, ensuring that Larsen Motorsports, and their sponsors, consistently deliver thrills without missing a run.
“For a professional race team, if we don’t make the lap, if we don’t squirt that car down the track, we’re not getting paid,” states Chris Larsen, crew chief, Larsen Motorsports. “We’ve got to make the laps, and that little welder has saved us.”
What’s so Neat about Drag Racing?
Drag racing is the largest participant-based sport in the country. Families form around the track as spectators and racers alike travel together from venue to venue for the love of the sport. “In North America, 52,000 licensed drivers within NHRA are wrenching and racing,” adds Larsen. “There is a class for everyone. Every one of those cars is someone’s little hot rod. If a ’69 Camaro or an ’81 Mustang is your deal, weld a roll bar on that baby and bring it to the track. We have a place for you!”
Elaine Larsen adds, “I think you better hang on because drag racing is going to skyrocket very quickly. It’s the only sport where everybody gets to come in and meet the drivers, meet the crew and watch them wrench the cars between heats. It’s really different than other spectator sports.”
Almost every team in drag racing welds on their own car. It’s about hot rodding and doing-it-yourself. “The rules are even built that way,” comments Chris Larsen. “They want you to use round mild steel or chrome-moly tubing. A lot of us are fabricating our own headers. This demands precision welding and good arc control TIG welding is the deal now.”
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At 13.7 lbs. the Maxstar 150 STH is portable enough for racers to take to the track.
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Getting the Wheels Turning
Chris Larsen grew up in a motorsports family. He’s also got a deep-rooted knowledge of aerospace technology and worked for the Cessna Aircraft Company for 17 years on their corporate Citation jets. These are private jets, with engines similar to the ones in jet cars. Larsen’s jet cars are powered by Pratt & Whitney J-60 or General Electric J-85 jet engines, which produce more than 6,000 horsepower at speeds approaching 300 miles per hour in a quarter of a mile.
With his love of aerospace and motorsports, Larsen naturally gravitated to drag racing jet cars, a sport, which began in the 60s and 70s. Many of the greats of the time, the Arfons and Gustin families, were all do-it-yourselfers, working out of their garages. They took military surplus jet engines and would fabricate a chassis around them. “These aren’t kit cars,” comments Chris Larsen. “There are no jet car kits out there. Our design and the jigs to make it are built from the ground up.”
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At Beach Bend Raceway, Bowling Green, KY, Chris Larsen uses the Maxstar 150 STH TIG welder to repair a crack in the afterburner of the Embry-Riddle jet dragster.
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Driven by Chris’s wife Elaine, the Larsen’s first jet car, known as the Miss Ta Fire, was a huge success. Following guidelines established by sanctioning bodies, the chassis was built from 4130 normalized chrome-moly tubing and had an aluminum body to keep the vehicle light. An engine obtained from a Navy T-2 Buckeye fighter produced 6,000 horsepower, 6,500 lbs. of thrust and a top speed of 300 miles per hour.
Safety is always Larsen’s number one concern, and the Miss Ta Fire exceeds all SFI, NHRA and IHRA required specifications. The aerodynamic knowledge that Chris Larsen possessed would prove to be invaluable for perfecting the design of his jet dragster. Little did he know that it would also attract one of the worlds biggest names in aerospace education.
A Winning Team
In 2004, Larsen Motorsports formed a mutual partnership with Embry-Riddle Aeronautical University (www.erau.edu) to re-engineer a jet dragster with the Aerospace Engineering and Aviation Maintenance Science Departments. A winning team formed instantly.
“Embry-Riddle is the largest, most prestigious aerospace training school in the world bar none,” states Chris Larsen. “If you want to learn to be a shuttle pilot, Embry-Riddle is the place to go. If you want to be an airplane mechanic or pilot, Embry-Riddle has you covered.”
The Larsens left the Miss Ta Fire dragster with Embry-Riddle for six weeks in the off-season. The aviation maintenance science students and engineering students came together to improve the track performance of an already fast vehicle, forming a propulsion and aerodynamic groups to work on the design.
“The students came to us and said that they could find some more speed while making the car safer,” comments Chris Larsen. “They planned to lighten the car in the right areas, as well as yield more power using stress analysis and computational fluid dynamics.”
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The completed weld, seen here, reattaches the support ring to the afterburner shell. Note the controlled heat input on this thin material.
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As a race team in an exhibition category, Larsen Motorsports was not worried about giving away any design secrets. “I told them, ‘whatever you show me, I’ll build it,” recalls Chris Larsen. “I’ll put it on the car as long as I’m certain it’s safe.” Open to design recommendations, custom components like the chassis geometry and afterburner configuration was redesigned for the best efficiency possible.
The power from the forward thrust of the afterburner and abrupt deployment of the parachute system puts a lot of stress on the car, requiring special attention from the propulsion team and lead fabricator and welder, John “Dr. Torch” Frazer of Larsen Motorsports. The military utilizes the afterburner on the engine slightly different than is desired for drag racing, which requires full power, at the starting line. The team modified the engine to go zero to 100 miles per hour in 1.3 seconds. And (300 in the five-second range). They also built a custom afterburner. Due to this “full-throttle” configuration, the 316L stainless steel afterburner glows cherry red from 1,400 degrees Fahrenheit of exhaust heat and a white-hot flame, which can weaken the metal. During a night run, the afterburner is so hot you can actually see straight through the 16-gauge metal. The students designed the outer cone of the afterburner to better maintain its rigidity because if the bottom-welded seams split, the pressure can lift the car right off the track.
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Driver Elaine Larsen of Larsen Motorsports.
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The Embry-Riddle jet car covers 800 feet of track per second, which makes stopping a priority. Jet cars do not use traditional brakes to stop; parachutes are everything. Welded to the strongest part of the frame, they are designed to pull evenly and withstand nearly 7Gs as the car comes to a stop, which can take a couple thousand feet.
Surprisingly, a jet car endures more damage from being towed from race to race than it experiences from a 5-second run down the track. One trip through a rough state is like 10,000 passes on the chassis down a racetrack. For this reason, the Embry-Riddle jet car has a strong rear suspension, which adds weight, but keeps the car safe while riding in the trailer. “When you think about it, the car is only moving down the track for 5 or 10 seconds a day,” comments Frazer. “That’s 20 seconds in a weekend that the car is actually moving under its own power. The rest of the time, it’s riding along and being moved in and out of the trailer.” The lighter the car, the thinner the tubing used, which makes it more prone to cracking. The Maxstar 150 is on hand as the jet cars are inspected after each race for cracks and structural damage. “You can’t risk buying a dime store welder for jet cars,” adds Chris Larsen. “If you’re racing jet cars or a 12-second Camaro, you need to have good equipment. That’s where Miller comes in.”
Dr. Torch is an alumni of Embry-Riddle and a certified FAA Airframe & Powerplant Mechanic. He used Miller welding equipment for years and had no idea what was in store when Chris Larsen asked him to weld with Miller’s Maxstar 150.
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Crew Chief Chris Larsen of Larsen Motorsports.
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“When we opened up the box, he just laughed at the small size,” recalls Chris Larsen. “After lighting it up, John didn’t want to give it back. We had to wrestle him for it.” Weighing 13.7 lb., the Maxstar 150 has a 5 to 150-amp welding range. Through its Auto-Line™ feature, the Maxstar 150 connects to 115 through 230 VAC single-phase power. Whether welding in the garage or at the track, operators can plug in the Maxstar 150 and begin welding without delay. Auto-Line also maintains a steady arc even if primary power varies when welding. A common problem, know as “dirty” power, found while running off some portable generators.
Track Practicality
Chris Larsen explains that the ERAU jet dragster’s chassis was welded back in his Fort Lauderdale, Fla., shop using a Syncrowave® 250. However, a machine weighing 378 lbs. is not practical to carry around, particularly if you’re a traveling racer.
“It hasn’t been practical in the past to carry a welder on the road until now,” states Chris Larsen. “If you’re caught in a bind without a welder at the track, you may be going home. Any racer can carry the Maxstar 150 along. It’s small, it’s compact and it does the job that the good old reliable Syncrowave 250 did on steel for so long before.”
The Maxstar 150 STH (Stick/TIG high frequency or Lift-Arc™ start) has the option for Pulsed TIG welding. Pulsed TIG welding reduces total heat input to prevent warping or burn-through in heat sensitive applications, such as the thin chrome-moly tubing and aluminum found in jet car fabrication. There are other tricks, like cutting relief holes into adjoining cross-members. This works to release the heat and pressure as one tube is welded perpendicularly to another. Frazer used the Maxstar 150 to weld the tubing around the driver’s compartment, a sensitive area responsible for the driver’s safety. Weld penetration is important for these joint clusters, some of which were so tight that Frazer had to use a mirror to weld around hidden corners.
“That is one of the best machines I’ve seen. I’d recommend it for any entry level home hobbyist whose looking to try TIG welding because it’s very fool proof,” adds Frazer. “I’ve tried other brands of equipment in the past and was really surprised at how much better the arc stability is and how easy it was to control the heat input.”
Pulsed TIG
Fabricators can easily attain professional-looking weld beads on thin metal by using a TIG welder with a built-in pulser. Pulsing reduces heat input by allowing the weld puddle to cool between pulses, minimizing burn-through and the warping effects of distortion.
When in the pulsed mode, the Maxstar 150 STH pulses the welding current between the set amperage and a value that is 50 percent of nominal. Fabricators have a selection of four fixed-pulse frequencies to chose from for varying material thickness: 0.5 pulses per second, 1.0 pulse per second, 2.5 pulses per second or 60 pulses per second.
Record Breaking Results
Embry-Riddle wired the dragster with a data acquisition system that reports on speed, telemetry, temperature and airflow a thousand times per second, helping them improve aerodynamics and streamline mechanical configurations. “We saw a 15 mile-per-hour increase in speed overnight,” comments Chris Larsen. “Straight out of the box, these kids put it together.” On the first pass down the track, Elaine immediately noticed the difference. “This is the best driving race car I’ve ever driven.”
Great things can be expected from the Larsen and Embry-Riddle team as they continue to rocket down the strip, breaking records both on and off the track. The knowledge gained from determined students in the field of aeronautics and aerodynamics is helping to push the envelope and interest in aerospace education. Larsen Motorsports consistently delivers a positive message with an entertaining and safe show for their sponsors and viewing spectators.
“It feels great to see where I can help change someone’s perception of what they want to do with their life,” comments Elaine Larsen. “Whether it’s aerospace or something else, I just want to get them focused on something. If by coming by my trailer and seeing the Embry-Riddle message gets them thinking about their future, that’s all I can ask for. I’ve won.”