In motorsports, race cars are designed to push boundaries to advance the sport. The DeltaWing team pushed beyond the bounds of conventional motorsport thought and created a new direction for the future of racing.
Ben Bowlby and his team of designers and engineers have a vision of racing that is a revolutionary peek into the future of competitive Motorsports. Instead of relying on higher horsepower to propel the increase in performance they created the DeltaWing with a “less is more” approach. The result is a dramatic increase in the efficiency the modern racecar.
Bowlbys’ challenge was to create a racing car that would perform at the same level as other Le Mans Prototype cars, but with only half the available horsepower! The math is easy: this means the car can only have half the mass and half the drag.
The unique design and construction of the DeltaWing car relies heavily on a cleaner aerodynamic shape that achieves a low drag coefficient while still creating enough down force to turn competitive lap times. This improvement requires less power to push the air at higher speeds, improving the efficiency of the vehicle operation.
Aerodynamic advantage was not the only goal of the DeltaWing team, though. Accelerating the car from low speed corners with only half the available power means the car can only weigh half as much, so an extreme weight loss program was key to making the car work.
To compound the challenge, the timing was a short 7 months from design to the first track test. So the team decided to use 3D printing technology together with Windform materials where applicable to shortcut the manufacturing time and save every bit of weight they could. In September 2011 they started to build the car at All American Racers (AAR) in Santa Ana, CA. In March 2012 Alex Gurney, test driver and son of DeltaWing constructor Dan Gurney became the first man to test the car at Buttonwillow Raceway in California.
During this process, Laser Sintered Windform XT 2.0 was used not only in prototyping and testing, but in mission critical applications on the car during the 24 hours of the Le Mans race, and continue to race at the Petit Le Mans, in the US. The DeltaWing team was able to move the bar for both racing and Additive Manufacturing applications forward.
Windform parts on the car included:
• Bespoke electronics enclosures
• Electrical breakout boxes
• Transmission seal covers with integrated pressurized oil feed passages
• Tow hook plinth
Windform parts used in prototyping, tooling & testing
• Brake inlets and ducting
• Air inlet ducting and filter enclosure
• BLAT – Underbody extension flange (5 foot long bonded assembly)
The carbon fiber reinforced Windform XT 2.0 was used to construct the gearbox side covers: The DeltaWing used a non- “stressed member” engine and gearbox to reduce the structural requirements of the assembly as well as reducing the vibration loads introduced into the lightweight car.
The gearbox with integral bell housing came in at a svelte 33 kg, a fraction of the other transmissions. Zack Eakin was the DeltaWing engineer responsible for the design of the gearbox: “Once we realized that we could use Windform XT 2.0 as a race-able part at the elevated temperatures and pressures we run the gearbox oil at, it opened up a big possibility for us that would have been cost and time prohibitive otherwise. We went for a design that put the output seal on the half shaft rather than around the outside of the Tripod joint which represents a big reduction in parasitic losses. But this design means that you have a seal that moves with suspension travel, a non-rotating CV Boot that will react to the seal drag, and that you need to somehow get oil into the tripod cavity. Creating a metallic part that would orient the CV boot perpendicular to the average half shaft angle, with integral oil drillings was a 5-axis machining job that still would be heavier than what Windform gave us. With rapid prototyping technology we were able to make a very complicated geometry, keep gentle radius’s in the oil passages, and get rid of all unnecessary material without introducing great cost or lead time in the parts. We were able to bond the CV boots directly to the Windform, seal directly to them with an O-Ring, and run the part at temperatures as high as 135oC, and pressures over 1 bar gauge without any issues. Windform was a real homerun for us on these parts”
Zack also believes the electrical enclosures were another very good fit for 3D printing technology “We designed a number of our own electrical controllers for things like the DRS and differential that we needed enclosures for. All an electrical enclosure needs to be is waterproof, durable, and have sufficient heat dissipation for the circuit it houses. We found that we couldn’t make an aluminum housing that was as light as a Windform one, let alone cost or time competitive. Often we would make a simple aluminum lid that the PCB would mount and heat sink to, which screwed into a Windform box via some tiny threaded inserts.”
Windform XT 2.0 was the material mostly used for the manufacturing of parts because of its mechanical and thermal characteristics. The use of 3d printing and Windform materials was fundamental to shorten the timing of car construction. In this case CRP Technology and CRP USA worked to support step by step the technical staff of the DeltaWing team in order to help them finding the best solution.
CRP Technology
www.crptechnology.com
