Audi R8 vrs R10, entrevista técnica
Publicado: 21 Mar 2006 20:53
La entrevista es con Mike Fuller (diseñador industrial // colega mio :) // - y experto en aerodinámica) , el más grande entusiasta de las competencias en Le Mans, especialmente en lo que respecta a las categorías ex GT1s , LMP2 y LMP1.
Información tomada de http://www.highlandstoday.com
Pd: Suena bonito "massive torque" !!!
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Recently, Audi revealed their new generation prototype, the R10, to replace their world-beating R8. Highlands Today sports reporter Steve Wilson contacted Mike Fuller, a wind tunnel model technician at Panoz/G-Force and race car design expert, to get his views on the new machine.
Fuller is better known as “Mulsanne Mike” and he runs a webpage, Mulsanne’s Corner, devoted to the design and technology of modern prototypes. Mulsanne is a reference to the infamous Mulsanne Straight on the Circuit De Sarthe, the network of roads where the 24 Hours of LeMans is run. Race cars on the 3.5-mile straightaway could reach over 230 mph, as Vic Elford did in a Porsche 917, roaring to a 240 mph speed on the stretch. A series of chicanes has slowed down the straight, but straight-line speed is still a huge part of a run at LeMans.
Fuller has always had a fascination with the design of these amazing machines and his site is an encyclopedic tome analysing nearly every prototype. According to Fuller’s biography on the site:
Fuller, who graduated from Auburn University with a bachelors of industrial design, has labored for several racing-related companies such as Downing/Atlanta, Riley & Scott, Reynard, and C&B International in such varied disciplines as composite lamination and wind tunnel model making. You can find Mike’s site at http://www.mulsannescorner.com/.
The Audi R10 will be one of several cars testing at Sebring International Raceway on Jan. 23-25 as part of the “Wheels Down Winter Test” in preparation for the 2006 Mobil 1 Twelve Hours of Sebring on March 18.
HT: What are some detail differences between the R 8 and R10 aerodynamically and in your expert opinion, why would Audi change some of those aspects of the car?
The R10 has a number of changes over the R8 and most of them are driven by the regulation change that occured a year ago. These regulation-driven changes are the raised front splitter, the raised outer floor section (chamfer), twin rollover hoops, the implementation of a near-spec underfloor tunnels (a move away from the previous generation flat bottom), longer wheelbase and revised overhangs, and a reduced chord rear wing. Outside of that, the most obvious difference between the two is the use of a new 5.5 liter turbo-diesel V12.
HT: Would you class the new R10 as an evolutionary step from the R8 rather than a revolutionary one?
While the R10 and R 8 are visually similar and the R10 is an evolution of the R 8 within the new regulations, there is an asterick in the R10’s diesel. Though understand diesels are not unique to Le Mans (nor racing for that matter –– diesels have even run at Indianapolis), it is the modern sportscar racing application that is of note and is quite significant.
HT: Were you suprised by the almost CIA-like secrecy surround-ing the car and how nary a single spy photo reached publication before the car’s debut?
No. Though when you think about it it is pretty impressive given the spread out and multi-national nature of the design team (believe Fondmetal contracts the wind tunnel testing for Audi, Dallara builds the car). You’d think something would leak, but no images came out and only the fewest of details.
HT: I noticed that the gearbox is only five gears vs. six in the R8. Why the move toward less gears when more seems to be the rule these days?
Really it comes down to the R10’s massive torque (800-plus pound-feet) and wide torque range. A sixth gear becomes superfluous with a wide torque band. Addition-ally there are more than likely reliability concerns and the removal of a gear allows for larger width gears (to better handle the torque) within a similar volume package.
HT: Do you believe that a diesel will withstand the rigors of 12 and 24 hour races and will it actually be an upgrade on the R8’s powerplant?
Yes, you have to think Audi will be on top of the R10’s reliability, after all the project got the green light two years ago and you have to assume the engine has been on the dyno a large portion of that time. And the diesel comes with many advantages within the regulations, namely variable geometry turbo chargers (turbo gas competitors must still use fixed geometry turbos) which allow for much better throttle response, larger diameter inlet restrictors allowing for equal if not more power than gas-powered competitors, diesels are allowed to refuel at a faster rate in that their refueling restrictor is of a larger diameter, diesel fuel has a higher energy content than gas and for a given cubic capacity (in this case 90 liters) a diesel engine will be expected to go further (more fuel efficient), finally, diesels produce awesome torque (800-plus pound-feet vs 500-plus pound-feet for the R8). So yes, you have to think the R10’s diesel is an upgrade.
HT: I know that the brake cowlings were not on the car photographed for the debut, but what do you think of the idea? Will it be an improvement over the old ways of ducting air onto the rotors?
Yes, and in this case this is evolutionary in as much as it has already been in use in F1 for some time. Figure since F1 cars are developed year after year it takes a while for ideas to trickle down into the less development intense series.
HT: On the subject of transmissions, what has Audi done to address the massive torque put out by the diesel? Are there more cooling inlets on the car to keep the gearbox from overheating?
That’s a tricky one to answer as they freely admit that the R10’s gearbox weighs less than the R 8’s! Intuitively you’d think at very least it would be equal in weight (given advances in design/materials over the past five years), certainly not less considering what the gearbox is being asked to handle. Cooling isn’t much of an additional issue with the R10 as far as the gearbox is concerned. Though quite the opposite with the diesel engine. Since the diesel’s ignition is reliant on high charge temperature (there is no spark plug as on gasoline engines), it is critical that the inlet charge’s temperature is controlled (hot but not too hot!) and therefore intercooling ducting is a more unique issue to the R10.
HT: Do you feel that the R10 will lead to a trend with more prototypes diesel-powered?
Most certainly. Since the inception of diesel regulations it has been pretty evident that was going to be an advantage. Figure better economy for equal horsepower and superior torque. The disadvantages are there of course with increased weight topping the list.
HT: How much of an improvement do you feel the diesel will make on fuel economy vs. the R 8 powerplant?
Well Audi claimed a possible 1-2 lap advantage at Le Mans over the R8, a track where a high percentage of the lap is at 100-percent throttle. So that will translate into a larger advantage at other circuits.
HT: Do you think the new rules (air conditioning in closed-top prototypes) will lead to more of the closed top prototypes in the future? Why this move by the ACO?
Possibly. In conjunction with the A/C regulation for closed top cars the ACO tacked an additional 25 kilograms of weight onto all competitors, open and closed top LMPs, making the weight minimums now 925 and 775 kilograms respectively (from 900 and 750). The ACO said this was to take into account the A/C equipment and to equalize the playing field between the A/C and non A/C competitors. In addition to that the ACO increased the engine inlet restrictor diameter for cars (closed top) with A/C in order to lessen the effects of the power drain on the engine caused by the cooling system. But there is a slight inlet diameter difference between closed top gas and diesel powered cars in that the diesel powered cars get a slightly larger increase (by .1 mm). As the inlet increase was to compensate for the A/C’s power sap from the engine, it seems odd that the ACO think air conditioners will have a larger effect on diesels (hence the need for larger diameter restrictor and therefore power) than gas engines. So when it gets down to it, if you’re going closed top you might as well have a look at a diesel engine as you’re allowed even slightly more power. That in itself could be the determining factor for those making the decision between open or closed top.
HT: Why the move to the larger front tires on the R10?
Weight distribution. Larger mass at the rear (V12 engine) and they want to move that weight forward as much as they can in order to reduce understeer. Moving it forward requires larger tires to handle that weight.
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