Delta Wing takes flight

Testing of the revolutionary Delta Wing begins in December, with a plan to race the car at Le Mans next year and, if testing goes well, to debut it at the Sebring 12 Hours in March. Originally conceived as a 2012 Indycar, the Delta Wing was rejected by that series’ Iconic’ committee last July in favour of a new Dallara chassis. But the radical new car was quickly embraced by the American Le Mans Series and Le Mans organiser the ACO, and an announcement was made at La Sarthe in June that the Delta Wing will race in next year’s 24 Hours as an additional 56th entry.

The ACO has created an extra grid slot for technologically innovative machines to compete outside the conventional classes, and the Delta Wing is the first such car to benefit. “We have to applaud the ACO for having the foresight to create this opportunity for an entry like ours,” says Delta Wing designer Ben Bowlby. “We believe this is a true automotive innovation which could be the catalyst for changing the way people look at not only racing car design, but automotive design as a whole.”

The prototype Delta Wing was built during the summer at Dan Gurney’s All American Racers in Santa Ana, California and will be run by Duncan Dayton’s ALMS championship-winning Highcroft Racing team. The American Le Mans Series founder Dan Panoz is a consultant to the combine, which calls itself ‘The Project 56 Group’, and ultimately Panoz is expected to build the first run of production Delta Wings at his facility outside Atlanta, Georgia. AAR founder Dan Gurney was the first man Bowlby asked to work on the prototype and it didn’t take long for the legendary racer and his son Justin, AAR’s CEO, to agree.

“After looking at the project and the technical aspects of the car, Justin and I didn’t hesitate for a moment,” says Gurney. “I have a lot of curiosity and when I first discussed this car with Ben I listened closely and tried to shoot holes in what he was saying, but found I wasn’t able to. I believe the targets and predictions are valid. The people here at AAR are all excited about it. I think it will appeal to a lot of people globally.”

The Delta Wing is unlike any racing car we’ve seen. To many, it looks more like a Land Speed Record car, with the front wheels placed together within a long, narrow nose and a complete absence of wings. It generates downforce entirely from its underwing, which is controlled by a Gurney Flap, and has an aeroplane-like vertical stabiliser.

Bowlby’s aim was to design a car that will make the same lap times as a contemporary Formula 1, Indycar or Le Mans prototype but with half the horsepower, half the weight, half the drag and half the fuel consumption. The Delta Wing weighs 475kg, will run on specially designed Michelin tyres and will be powered by a 1.6-litre, four-cylinder turbo engine.

Bowlby’s career began while at college in the UK. In 1985 he built a motorcycle-powered ‘special saloon’ with an aluminium monocoque and composite body. While studying for his engineering degree he then built and raced his own Bowlby clubman’s car. After graduation he was hired by Lola Cars where he became chief designer in 1997, before moving to Chip Ganassi Racing in 2003 where as technical director he worked on its three-pronged NASCAR, Indycar and Grand-Am campaigns.

To properly explore and define the parameters for the Delta Wing, Bowlby tried to reach as wide a pool of information and resources as possible. “We talked with many engineers in IndyCar and elsewhere,” he says. “We discussed our ideas, got input and looked at the different areas of opportunity. It was really about, ‘If we threw the rule book away, what could we do?’ We met with [General Motors’ safety expert] Dr John Melvin and talked about if we had a clean sheet of paper what would we do with the positioning of the driver? We took in many different sources of information to pull this thing together.”

The Delta Wing’s aim was to rewrite the rules and efficiency standards for motor racing in the 21st century. “We tried to make a car that had clean lines and was appealing to the eye,” says Bowlby. “But this wasn’t a styling exercise. To use a well-worn phrase, form follows function. Nothing on this car is there to look cool. It’s about creating the most efficient, best-handling racing machine we could come up with.”

Bowlby and his team of engineers had not intended to come up with such a radical design. “We didn’t set out to create a car with a narrow front track, wide rear track and 72.5 per cent rear weight distribution,” he says. “We set out to produce a modern, efficient, relevant, hi-tech and low-cost racing car that had the latest in safety and accident prevention built into it as well as longevity, recyclability and modern materials. Our goal was to integrate all of these aspects into the car.

“The car’s shape came from realising that if we truly wanted to make a real improvement in efficiency, with a halving of the fuel burn, then we needed to reduce the drag dramatically. We had to halve it in gross terms and we actually went a little further. In order to get our power-to-weight ratio we had to halve the weight because we were going to have half the power. We realised that we had to enclose the wheels to reduce the aerodynamic drag of the exposed rotating wheels.”

One of the goals was to produce a car that is more capable of running in close quarters with and able to pass other cars. “We had to get rid of the front wings because they were far too sensitive in terms of angle of attack and interaction with the underbody,” says Bowlby. “That interaction between the wings and the underbody is a big part of the reason why it’s so hard to overtake when you’re in the turbulence from cars in front and behind.

The First trick was to substantially reduce the Delta Wing’s overall drag coefficient. “The wheels currently account for 54 per cent of the drag of a car at Indianapolis,” explains Bowlby. “That led to the Delta Wing concept where we had a narrow front track and wide rear track. We did some simulation experiments and to our great surprise the vehicle dynamics were incredible.”

The more Bowlby and his team looked at the concept the more they realised it would not only accelerate much quicker but would also be more stable under braking. This is the opposite of what conventional wisdom might suggest, but such lessons were learned by aircraft manufacturers more than half a century ACO during World War II.

“We discovered that if we had the weight more rearwards,” explains Bowlby, “then in a straight line competition we could out accelerate the current Indycar because more of our weight is on the two rear tyres which are powered. That gives us greater acceleration capabilities. Under braking we found we had created a unique condition — in racing car terms — where more than 50 per cent of the braking came from behind the centre of gravity. Normally, that amount of braking comes from in front of the centre of gravity, and that’s an unstable condition where you have to be terribly careful not to lock the rear brakes.”

Another key component in Bowlby’s thinking was to link the Delta Wing’s basic parameters to the automobile industry’s ever-increasing search for more efficient engines and overall designs. “We identified trends in the automotive industry and global social trends towards higher efficiency and reduced waste,” he says. “This is where racing is relevant in producing the more efficient cars that the automotive manufacturers are committed to.”

The most common question about the Delta Wing is how will it turn effectively without suffering from serious understeer? But Bowlby points out: “By having the weight rearwards we’ve unloaded demand on the front tyres. They only have to manage a very small percentage of the mass of the vehicle and have a large leverage on the centre of gravity.”

Bowlby says the Delta Wing will generate most of its downforce through the underbody. “Downforce is created by a simple shape underneath the car. It’s a venturi that creates low pressure pretty much under the car’s centre of gravity. It is not sensitive to ride height changes or pitch angle, so you’ve got a consistent downforce area.”

Without the need for a rear wing to generate downforce or provide aerodynamic balance, the Delta Wing uses a vertical tail fin to aid directional stability. “With the weight rearwards we wanted a high degree of yaw stability to increase the envelope a driver can explore in the middle of a turn, so we moved the lateral centre of pressure back to give ourselves an appropriate stability margin, known in the aircraft world as a ‘static margin’. That means that when the car is in yaw you don’t have a destabilising moment, or torque, that tries to create more oversteer.

“It’s like the feathers on a dart. You have to put lateral force components far more rearwards on the bodywork than we have. In gross terms the aero balance puts around 77 per cent on the rear of the car. We’ll use the mechanical solution of the torque vectoring or torque steer of the diff to alter the balance, which will be completely unaffected by the proximity of another car.

“The electronic differential is an exciting area. Rather than being a passive device that’s inconsistent and temperamental, it becomes your ally. It’s a balance-adjusting, driver-adjustable tuning device.”

Bowlby says improved safety is a keystone of the Delta Wing, thanks to its revolutionary aerodynamic parameters and lighter weight. “One of the nice things about a light car is you don’t have as much energy to absorb.”

The driver is located 20 inches further back and sits in a more upright position than in any recent Fl or Indycar. “The driver’s spine is closer to being vertical. This is important for surviving heavy front or rear impacts without putting too much strain on the spine and neck and causing basal skull fractures.”

To further improve driver safety, the team has incorporated a new and much more crushable polypropylene composite material called Tegris into the chassis, which Bowlby says is less likely to rupture than conventional carbon fibre. “Tegris is a fully recyclable, lowcost material with high stiffness, extraordinary strength-to-weight ratio and enormous energy-absorbing properties.”

Dayton admits it will be difficult to get the Delta Wing built, tested and ready to race in under a year. “We’re hoping to race the car at Sebring but the timeline is very short. The car probably won’t hit the track until December. We’ve pencilled in 22 test days before Le Mans. That’s an appropriate number, but obviously a lot of things can get in the way of doing that. But that’s what we’re shooting for; it would be great to get a good run in competition before we have to take it to Le Mans.”

ALMS boss Scott Atherton says he would like to see the Delta Wing race regularly in next year’s series following its Le Mans debut. “I think there will be a lot of interest in watching how something so radical can work so well,” he says. “Next year is the 80th running of the Le Mans 24 Hours and there’s no question in my mind that if the Delta Wing is there it will be the story of the race.” And the beginning of a revolutionary motor racing adventure.

Gordon Kirby