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Prototype sport Delta Wing project: revolution or hocus-pocus?

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The reactions are roughly the same as those you get when asked whether someone believes in UFOs - raised eyebrows, throwing hand movements, ironically curled corners of the mouth and slightly disparaging comments. The Delta Wing project by the American designer Ben Bowlby is ridiculed by the leading engineers in the sports car guild - but rarely taken seriously.

D his assessment has a long tradition. The car was already like a UFO from another planet when it was traded as a candidate for the successor generation of the IndyCar chassis in 2010. Spectacular? For sure. Inspiring confidence? Rather no. Indycar opted for a conventional formula car design from Dallara. The risk seemed too great that, without the assistance of conventional wings, a car could mutate into a stealth bomber that would tear down a safety fence on the ultra-fast American ovals.

Faible for extroverted ideas

But for Ben Bowlby there was a second chance after the defeat: the bosses of the Le Mans organizer ACO have a weakness for extroverted ideas, after all they are French. So they shoveled an additional 56th starting place as a lane for innovation and unusualness, in order to bring the bizarre wonder-work to Le Mans. The Delta Wing concept meandered into the sports car scene - as Project 56.

With a three-month delay, the car drove for the first time on Thursday, March 1, 2012, at the Buttonwillow Raceway in California. No, despite all the warnings, the bizarre dugout did not take off and disappeared into the mesosphere. And yes, he even drove quickly around the bend. The video evidence was immediately posted on the World Wide Web, as one strives for a serious appearance at all: With Dan Gurney and his team All American Racers (AAR), a hero of American motorsport has been won as a construction expert. And the American millionaire Duncan Dayton and his Highcroft Racing team are also a recognized heavyweight in motorsport. In times of doubt you can never have enough supporters, so ALMS founder Don Panoz was also lured as a consultant.

Is someone buying up credibility? The fact that Michelin is now even supporting the project as a tire partner - as a replacement for Firestone /Bridgestone, who had probably lost their faith a little in the middle - is appreciated by manyInsider as an indication that Ben Bowlby could not have calculated that wrong. Because Michelin has a reputation for judging facts in a rather humorless way. And the fact that a large Japanese manufacturer - Nissan - has provided a 1.6-liter turbo engine and has papered the cigar-shaped cart with large stickers makes both suspicious and curious at the same time.

Is there anything to the Delta Wing wonder car after all?

The radical concept follows a clear idea: Instead of following the current trend in the prototype business - large and heavy cars, a lot of wing stuff, huge engines with brute power - Ben Bowlby is radically relying on the opposite: low weight , smallest possible frontal area, little air resistance by omitting classic aerodynamic aids such as wings free in the wind. These framework conditions make it possible to achieve good performance with a compact and small-volume motor and a light transmission. Up to this point, every engineer will nod in agreement. But then the group of viewers breaks up into yes men and naysayers.

For the British Ben Bowlby, who set up his own business in 2009 after having worked as technical director at Lola and Chip Ganassi Racing, the cornerstone of the program consists of the extremely favorable ratio of lift to drag coefficient (lift to-drag ratio). “According to our calculations, the Delta Wing car creates a downforce of 950 kilograms at 320 km /h, with a dry weight of around 475 kilograms. The downforce is not generated via conventional wing profiles, but via the underbody and the negative pressure zones in front of the rear wheels.

Streamlined chassis without wings

By doing without wings, we get an extremely streamlined chassis that is significantly less Resistance produces than a conventional LMP1 car. Conversely, that means: We don't need gigantic engine power like conventional LMP1s because we don't offer much resistance to the air without wings. We are thus turning the established LMP philosophy on its head, according to which you have to invest a lot of money to generate downforce through drag, which in turn means that you walk a lot of gasoline to get ridiculously high engine performance. We want to break this cycle with the Delta Wing concept. ”

The low air resistance and adequate downforce allow the designer to plan for the engine with modest performance: the 1.6-liter turbo engine from Nissan makes only 300 hp and 400 Newton meters of torque in racing trim. The compact engine weighs only 70 kilos, the tank measures a tiny 40 liters. The EMCO five-speed longitudinal transmission with torque vectoring differential also only weighs 32 kilograms, which brings us to the second central cornerstone of theDelta Wing concept: weight.

Total weight well below 500 kilos

The central monocoque (tub) of the Aston serves as the basis of the car Martin LMP1 from 2011. This car was not very successful - to put it nicely. But the tub is very popular with independent teams, because it saves the effort of the prescribed crash tests and its use thus saves a significant amount of time. The monocoque is also nice and light at 70 kg. For the outer skin, the REAMS system from the Panoz Group is used, an extremely light material mix of Kevlar, carbon, aluminum and titanium. With these ingredients Bowlby and his like-minded comrades push the total weight well below the 500 kilo mark.

Most viewers smile when they inspect the cigar-shaped silhouette of the Delta Wing Nissan: The rear of the car is as wide as a bathtub, the driver crouches directly in front of the rear axle - almost like in the legendary Panoz-LMP1. While the Panoz had a front-engined V8 and the seating position had to be rearranged inevitably, the Delta Wing had an at first glance ridiculously long snout protruding forward, whose task seems to be nothing more than to carry the front axle and steering .

That leads to a cheeky narrow track width on the front axle of just 60 centimeters, while on the rear axle there is a track width of 170 centimeters. While the track widths were increased in the course of the conversion from the IndyCar showmobile to the LMP1 projectile and, in return, the wheelbase (from 3175 to 2900 millimeters) and the overall length were compressed, the sheer chassis dimensions naturally also have an impact on the tire widths: Measure at the front The Siamese twin tires from Michelin are delicate 100 millimeters, while the rear, on the other hand, enthrones 31.2 centimeters of fat 15-inch pines in the wheelhouses.

Delta wing car against the established trend

A disproportion? Again, the Delta Wing Car runs completely against the established trend: For two years now, the LMP1 teams have been driving with monstrously wide tires on the front axle to convert the downforce at the front into grip. Bowlby: “You only need extremely wide tires if you concentrate a lot of mass and a lot of downforce on the front end. We have little mass and little downforce - and that's why narrow tires are completely sufficient. ”

The desolate proportions and the bizarre tire widths of the Delta Wing Car lead many observers to the premature assumption that this car can never turn over quickly drive a curve. But be careful, experts warn, because two aspects should not be overlooked: First, the weight distribution and, second, the aero balance. Just 27.5% of the weight is on the meager front wheelsTotal weight, the rear wheels bear 72.5% of the static load. These numbers correlate almost exactly with the ratio of the selected tire dimensions. The tires are well proportioned in relation to the longitudinal forces to be absorbed and, above all, lateral forces in the curves, depending on the vehicle weight.

Critics complain that the narrow front wheels could reach their limits, especially when braking, but designer Bowlby counters: “The center of gravity is far back, and the mass of the downforce is also generated in the rear area. Therefore, the Delta Wing Car will transfer well over 50 percent of its braking power to the rear wheels - this is unique in the sports car sector. ”Bowlby also counters the risk of the rear wheels floating up in the rain because the front wheels hardly displace any water in the lane : “Aquaplaning occurs first and foremost on the front wheels when they float up. Our front tires are so narrow that we hardly have to deal with a hydroplaning problem. ”

Interplay of weight distribution and aero balance

The crux of the matter when it comes to traction and grip of the Delta Wing Car is the interplay of weight distribution and aero balance. The aero balance is distributed symmetrically to the weight balance: two thirds of the aero load goes on the wide rear wheels, only 24 percent on the front wheels - although the downforce is generated relatively far back. But where does the downforce on the wingless US LMP come from?

First of all, it must be pointed out that the Delta Wing LMP will not be rated at Le Mans. By using the AMR tub, it fulfills the safety and crash regulations as well as the required two-seater. And from a formal point of view, it also fits into the ACO-LMP box measuring two by five meters. But that's where the similarities with all other LMP1 cars end. And these are extremely limited by regulations, especially when it comes to the underbody and the front and rear diffusers. The Delta Wing exotic, on the other hand, can draw on the full: It has a fully formed and unregulated front diffuser, and especially in the rear area, Bowlby was able to let off steam to its heart's content - otherwise it would not work without wings. The fact that Bowlby is allowed to explore its aero concept so radically means that the downforce generated almost exclusively via the underbody is generated in a stable manner and neither has to be bought at the cost of a rock-hard set-up nor is it compromised by fluctuations in the vehicle height. One disadvantage, however, remains: Trimming the aerodynamics without the classic wings will be a tightrope walk.

No danger for Audi or Toyota

The ACO has given the Delta Wing makers a clear time corridor , in which the car at the 24h race in LeMans 2012 should stop: 'Lap times in the range of 3.35 to 3.40 minutes are realistic and absolutely feasible,' claims Ben Bowlby. “With the small engine, we should be able to do 12 or 13 laps per stint. And then a second joker stands out: Due to the low mass, we should drive quadruple or quintuple stints with the Michelin tires. ”This makes it clear that the slim Delta-Wing car will of course not pose any threat to Audi or Toyota. Rather, the Highcroft Racing team will be in the midst of the LMP2 field, but this could at least offer the prospect of a top ten placement. With the support of the ACO - to put it bluntly - Ben Bowlby threw the LMP rule book in the garbage can and presents a completely new and unencumbered design approach. However, if the ACO is serious about approval, the positive elements of the Delta Wing test balloon must also find their way into the LMP regulations at some point - otherwise the number will fizzle out.

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