Discussion - is there a design issue with LMP

[chernaudi]

And it seems that there is little doubt that something long-term does need to be done to try to keep these cars on the ground.

But I do feel that the ACO screwed up in some ways. First, if they were so concerned with slowing the cars down, why give them first the same horsepower that they had in 2002, and then about 30-40 more for the gasoline cars on top of that?

Also, these cars are using basically a modified Group C type undertray. Granted, there are differences-the angled outer floor, and the 20mm skid-but the big one is that Group C cars didn't have nose diffusers-Group C cars had simple spitters, LMP cars have actual diffusers.

Combine those factors with the fact that the tires are producing more grip than ever, of couse the cars are almost 8 seconds a lap faster than in the Audi R8 dominated LMP900 era.

Of course, Michele Alboreto died in an accident that was similar to that which killed Greg Moore and also similar to the one that Gene had today. If Gene's Pug hit the wall with it's roof instead of its nose and tail, as morbid as is sounds, we could be reading Gene's obitulary, instead of positive medical reports confirming only very minor injuries(considering the accident) and that Marc will race come June 14th.

The HANS probably also probably saved Gene from a basilar skull fracture and/or internal decapitation/broken neck. But does the HANS also need a face lift soon, too?

Agentinian sportscar driver Julián Alfaro died from a basilar skull fracture in an accident, inspite of wearing a HANS: http://www.motorsportmemorial.org/fo...p?db=ct&n=3295

And add to that the fact that Ashely Cooper died from possibly a broken neck(in this case likely a C1 vertebra fracture or internal decapitation causing blood flow to be resticted to his brain, causing him to lapse into an irreversable coma).

Both Alfaro and Cooper were wearing HANS devices, but still died from head and neck injures.

We are fortunate in living in an era where you're exponentially more likely to be seriously injured or killed in an accident on the highway than you are on a racetrack. But NASCAR driver Jeff Burton has reminded us time an again that safety is a moving targer, and always will be as long as the cars keep going faster and both race car and race car safety advances. And the only way to keep the status quo(where your more likely to die in a road accident than a racing accident) or improve it is if advances in speed and safety go hand and hand.

[MulsanneMike]

Originally Posted by chernaudi

And it seems that there is little doubt that something long-term does need to be done to try to keep these cars on the ground.

But I do feel that the ACO screwed up in some ways. First, if they were so concerned with slowing the cars down, why give them first the same horsepower that they had in 2002, and then about 30-40 more for the gasoline cars on top of that?

Also, these cars are using basically a modified Group C type undertray. Granted, there are differences-the angled outer floor, and the 20mm skid-but the big one is that Group C cars didn't have nose diffusers-Group C cars had simple spitters, LMP cars have actual diffusers.

Combine those factors with the fact that the tires are producing more grip than ever, of couse the cars are almost 8 seconds a lap faster than in the Audi R8 dominated LMP900 era.

Of course, Michele Alboreto died in an accident that was similar to that which killed Greg Moore and also similar to the one that Gene had today. If Gene's Pug hit the wall with it's roof instead of its nose and tail, as morbid as is sounds, we could be reading Gene's obitulary, instead of positive medical reports confirming only very minor injuries(considering the accident) and that Marc will race come June 14th.

The HANS probably also probably saved Gene from a basilar skull fracture and/or internal decapitation/broken neck. But does the HANS also need a face lift soon, too?

Agentinian sportscar driver Julián Alfaro died from a basilar skull fracture in an accident, inspite of wearing a HANS: http://www.motorsportmemorial.org/fo...p?db=ct&n=3295

And add to that the fact that Ashely Cooper died from possibly a broken neck(in this case likely a C1 vertebra fracture or internal decapitation causing blood flow to be resticted to his brain, causing him to lapse into an irreversable coma).

Both Alfaro and Cooper were wearing HANS devices, but still died from head and neck injures.

We are fortunate in living in an era where you're exponentially more likely to be seriously injured or killed in an accident on the highway than you are on a racetrack. But NASCAR driver Jeff Burton has reminded us time an again that safety is a moving targer, and always will be as long as the cars keep going faster and both race car and race car safety advances. And the only way to keep the status quo(where your more likely to die in a road accident than a racing accident) or improve it is if advances in speed and safety go hand and hand.

Today's cars still rely way more on the splitter and rear wing for their total downforce than Group C/GTP cars ever did. The underfloor that is on these cars is nothing like a Group C/GTP underfloor and hence the method in which the cars make downforce completely different. All one has to do is look at total downforce numbers to see there is a large difference. And 30-40 more horsepower makes frankly little difference in top speed in the scheme of things. Combine that with the mandatory 15 mm gurney in addition to the mandatory rear structures and you have some rather draggy mandated items on the car to counter that small (relative to 2002) hp increase.

[chernaudi]

But 610-620hp in '02 vs almost 700hp for the diesels and the Lola-Aston as well as at least 680 for everyone else seems to outweight any changes areo wise.

My argument I have is if the ACO were so concerned with reducing speeds, why give these guys more power than they had even in 2002, more downforce than they had back then, and combine that with better tires than ever? Case in point, Sarazin's lap today easily would've put in in the top 3 or 5 on the gird in '92, and the pole in '93. These are lap times that until today were supposed to be at least theoretically impossible.

And as I mentioned, there are plenty of differences between a Group C floor pan and an LMP1 floorpan, but mate that huge rear diffuser with a front diffuser(something that Group C cars never had before rule changes killed them off after '93), that's plenty of downforce, even by Group C standards for a cirucuit at Le Mans.

Maybe the solution is to make Michelin, Dunlop, Pirelli and eveyone else bring harder tires at Le Mans in the future. But this will only work with a spec tire supplier, and Le Mans style endurance racing is anathema to the word "spec", and the cars are on edge enough right now-the last thing that's needed, as you said at your site(and everyone is in agreement on this fact), is something that inadvertanly makes things worse.

[Tom87]

Originally Posted by chernaudi

But 610-620hp in '02 vs almost 700hp for the diesels and the Lola-Aston as well as at least 680 for everyone else seems to outweight any changes areo wise.

My argument I have is if the ACO were so concerned with reducing speeds, why give these guys more power than they had even in 2002, more downforce than they had back then, and combine that with better tires than ever? Case in point, Sarazin's lap today easily would've put in in the top 3 or 5 on the gird in '92, and the pole in '93. These are lap times that until today were supposed to be at least theoretically impossible.

And as I mentioned, there are plenty of differences between a Group C floor pan and an LMP1 floorpan, but mate that huge rear diffuser with a front diffuser(something that Group C cars never had before rule changes killed them off after '93), that's plenty of downforce, even by Group C standards for a cirucuit at Le Mans.

Maybe the solution is to make Michelin, Dunlop, Pirelli and eveyone else bring harder tires at Le Mans in the future. But this will only work with a spec tire supplier, and Le Mans style endurance racing is anathema to the word "spec", and the cars are on edge enough right now-the last thing that's needed, as you said at your site(and everyone is in agreement on this fact), is something that inadvertanly makes things worse.

The question I have is *which* speed should be reduced - neither cornering speed or straight line speed appear to have been the key factor in any of these accidents (although without a full video of Gene's crash its hard to say). I do also wonder why we haven't seen these accidents in previous years as the measures designed to prevent these accidents mandated in 2003 do appear to be insufficient.

Although I agree, action needs to be taken, it's difficult to see exactly what can be done until there is a total understanding of the initial cause of the accidents.

[dj choc ice]

Originally Posted by Tom87

The question I have is *which* speed should be reduced - neither cornering speed or straight line speed appear to have been the key factor in any of these accidents (although without a full video of Gene's crash its hard to say). I do also wonder why we haven't seen these accidents in previous years as the measures designed to prevent these accidents mandated in 2003 do appear to be insufficient.

Although I agree, action needs to be taken, it's difficult to see exactly what can be done until there is a total understanding of the initial cause of the accidents.

have you checked PLM?

the ACO have released the video of gene's crash, gene definetely gets on the grass and by the looks of it the car effectively 'wall rides' on the outside of the corner and as the barrier peels of, the car spins and while on the grass it flips.

the quality of the video isnt brilliant but just my two cents, there does appear to be a problem with the side aero at high speed but after all, isnt motorsport dangerous anyway and no matter how safe the cars are made accidents are always going to happen.

IMO, it might be time to take some kind of action on the aero of the cars, so far we have been extremely lucky that we havent had a situation similar to michele alboreto at lausitz were a car has vaulted over the barrier at high speed and landed on its roof.

[zac510]

I don't think he hit the barrier on the left hander at all.

[Tom87]

Originally Posted by dj choc ice

have you checked PLM?

the ACO have released the video of gene's crash, gene definetely gets on the grass and by the looks of it the car effectively 'wall rides' on the outside of the corner and as the barrier peels of, the car spins and while on the grass it flips.

the quality of the video isnt brilliant but just my two cents, there does appear to be a problem with the side aero at high speed but after all, isnt motorsport dangerous anyway and no matter how safe the cars are made accidents are always going to happen.

IMO, it might be time to take some kind of action on the aero of the cars, so far we have been extremely lucky that we havent had a situation similar to michele alboreto at lausitz were a car has vaulted over the barrier at high speed and landed on its roof.

I've seen the video, but you can't see what causes the accident prior to leaving the track or precisely what caused the car to get airborne.

The angled sidepods do their job to some extent as there hasn't been evidence of actual lift being produced over the whole surface of the car (the cars aren't actually flying a la DBR9 at Road America, just 'tipping' upright), instead once the car rolls due to the grass or whatever else, the undertray is pitching upwards due to the momentum of the air.

[AU N EGL]

Originally Posted by Tom87

I've seen the video, but you can't see what causes the accident prior to leaving the track or precisely what caused the car to get airborne.

The angled sidepods do their job to some extent as there hasn't been evidence of actual lift being produced over the whole surface of the car (the cars aren't actually flying a la DBR9 at Road America, just 'tipping' upright), instead once the car rolls due to the grass or whatever else, the undertray is pitching upwards due to the momentum of the air.

Look though the fence to the upper left. You can see the PUG come though the corner and the rear come around before it gets in front of the camera.

Almost like snap over steer or something the suppension broke would be my guess.

[Tom87]

I agree thats what looks most likely, my point is that assuming this is the case, slowing the cars down would not have prevented the accident.

Or looked at from the other direction, an open wheeler such as a Formula One, which doesn't suffer from this inherrant problem would not have become airboune in these circumstances despite even higher cornering speeds.

[JAG]

Originally Posted by chernaudi

But 610-620hp in '02 vs almost 700hp for the diesels and the Lola-Aston as well as at least 680 for everyone else seems to outweight any changes areo wise.

My argument I have is if the ACO were so concerned with reducing speeds, why give these guys more power than they had even in 2002, more downforce than they had back then, and combine that with better tires than ever? Case in point, Sarazin's lap today easily would've put in in the top 3 or 5 on the gird in '92, and the pole in '93. These are lap times that until today were supposed to be at least theoretically impossible.

And as I mentioned, there are plenty of differences between a Group C floor pan and an LMP1 floorpan, but mate that huge rear diffuser with a front diffuser(something that Group C cars never had before rule changes killed them off after '93), that's plenty of downforce, even by Group C standards for a cirucuit at Le Mans.

Maybe the solution is to make Michelin, Dunlop, Pirelli and eveyone else bring harder tires at Le Mans in the future. But this will only work with a spec tire supplier, and Le Mans style endurance racing is anathema to the word "spec", and the cars are on edge enough right now-the last thing that's needed, as you said at your site(and everyone is in agreement on this fact), is something that inadvertanly makes things worse.

Those '02 R8's had in excess of 660bhp, which is +/- 15bhp what a current petrol P1 has.

Also look at the times, no petrol P1 got within 3 seconds of 3.30, which is the target race pace.

One of the issues is that a P1 908 produces MORE downforce than an F1 car, then consider F1 is reducing downforce by 30%+ next season.

The ACO need to look at reducing the efficiency of the splitter/rear wing to GT2 levels, and let the cars rely more on mechanical grip, afterall they are gaining 4 seconds a year at Le Mans.

[Tom87]

Originally Posted by JAG

Those '02 R8's had in excess of 660bhp, which is +/- 15bhp what a current petrol P1 has.

Also look at the times, no petrol P1 got within 3 seconds of 3.30, which is the target race pace.

One of the issues is that a P1 908 produces MORE downforce than an F1 car, then consider F1 is reducing downforce by 30%+ next season.

The ACO need to look at reducing the efficiency of the splitter/rear wing to GT2 levels, and let the cars rely more on mechanical grip, afterall they are gaining 4 seconds a year at Le Mans.

But it isn't the rear wing or the splitter which causes this type of accident and cornering speeds aren't the major contributing factor - all the accidents except for Ben Devlin's and Gene's occured on a straight. Its even questionable whether removing all aerodynamic grip would have prevented Ortelli's accident - he left the track as a result of a mechanical failure and flipped over as a result of the cars aerodynamic profile when pitched. Same goes for JCW's accident.

[Pingguest]

I think the problem as we saw with Gene are inherently to Prototypes, aren't they? I've seen many crashes in Group C, GT1 (as it was in the late 1990's) and LMP1 where the cars start to generate a lift. The problem is caused by the undertray. If you really want to resolve the problem totally, you should ban the use of any sort of undertray. The cars did so until the 1970's, so it wouldn't be impossible to without it again.

[bil588]

Originally Posted by The Badger

Can we count the B-K Sebring accident as well . It did flip but im not sure if it clipped the wall before . Then we have 4 nasty accidents .

Hats off the the men who design the car !!!

Looking at the Gene/Peugeot accident , it kinda reminded me of the attitude which Greg Moore had hit the wall and died . If that Pug hadn't uprighted itself some , when its left side landed first , it could very well have been the cockpit that contacted the wall first and that outcome would not be something nice to think about .

B-K's Lola was hit the wall hard.

Gene's 908 was sideways when it flipped as was Ortelli's Courage-Oreca LC70 Judd.

[Tom87]

Originally Posted by Pingguest

I think the problem as we saw with Gene are inherently to Prototypes, aren't they? I've seen many crashes in Group C, GT1 (as it was in the late 1990's) and LMP1 where the cars start to generate a lift. The problem is caused by the undertray. If you really want to resolve the problem totally, you should ban the use of any sort of undertray. The cars did so until the 1970's, so it wouldn't be impossible to without it again.

I agree, however If you look at airbourne accidents during either the GT1 or Group C era the car creates more lift than the recent LMP accidents - in many cases the cars fly right into the air. For example this accident at Fuji is very similar to Ortelli's accident but the car flys much higher despite a probably lower take off speed and no contribution from a bumpy run off area.

http://www.youtube.com/watch?v=2e-Zad4mFb0

[Fogelhund]

In this incident, I believe that the two contributors are a drop in the elevation off the track, and possibly the rear wing. It would appear as though the bottom of the car actually contributed to the front end changing direction, which led to the car falling back to the ground.

[MulsanneMike]

Originally Posted by Pingguest

I think the problem as we saw with Gene are inherently to Prototypes, aren't they? I've seen many crashes in Group C, GT1 (as it was in the late 1990's) and LMP1 where the cars start to generate a lift. The problem is caused by the undertray. If you really want to resolve the problem totally, you should ban the use of any sort of undertray. The cars did so until the 1970's, so it wouldn't be impossible to without it again.

These incidents can be traced back to the 60s, there isn't any intrinsic relationship between under floors and this type of aero instability. It has all to do with underbody area. No matter if that area is tunneled, flat bottomed, or even "open" ala a production car.

[JAG]

Originally Posted by Tom87

But it isn't the rear wing or the splitter which causes this type of accident and cornering speeds aren't the major contributing factor - all the accidents except for Ben Devlin's and Gene's occured on a straight. Its even questionable whether removing all aerodynamic grip would have prevented Ortelli's accident - he left the track as a result of a mechanical failure and flipped over as a result of the cars aerodynamic profile when pitched. Same goes for JCW's accident.

I just think the cars should rely less on aero, and focus more on mechanical grip like a GT car.

Developments with tyres, suspension, and the general shape of a prototype, which generates plenty of downforce minus the splitter/rear wing, is enough. Cars are gaining 4 seconds a year, so even a 908 with these fairly radical changes would still run in the 3.30+ range, with development to spare.

At the moment any sudden loss of the considerable amount of downforce generated invariably sends the car into a high speed spin, so that potential to create an accident could be minimised.

Part two is looking at ways to stop cars getting airborne. Right now the flight of the car is under control, compared to Group C and GT1, can they be prevented from taking off altogether?

[MulsanneMike]

Not sure where I see total downforce levels playing any part into the equation. The problem is that the shape of the cars in cross section promotes lift that counteracts car weight when large yaw angles are encountered. Point of fact is that the cars aren't meant to travel sideways!

[Tom87]

Originally Posted by MulsanneMike

These incidents can be traced back to the 60s, there isn't any intrinsic relationship between under floors and this type of aero instability. It has all to do with underbody area. No matter if that area is tunneled, flat bottomed, or even "open" ala a production car.

As you say - any large flat area parallel to flow on the underside will produce lift when combined with the aerofoil like curves on the top surface - so what about londitudinal strakes to distrupt the flow when pitched?

[zac510]

Originally Posted by JAG

At the moment any sudden loss of the considerable amount of downforce generated invariably sends the car into a high speed spin, so that potential to create an accident could be minimised.

In a few of the cases, and the cases of old prototypes launching as shown on Mike's youtube channel, the cars have not really been sent into a high speed spin (which I interpret to mean high speed rotation). They have more been spun, by a failure of some type, but it appears that it takes a little bit of time (let's saw 1/4-1/2 second) at the perpendicular angle to actually generate lift for takeoff. The 1981 and 1991 flights at Fuji look like the car got 'stuck' at ~90degrees to direction of travel, then took off. If the car really was spinning at a high rate it would spend less time perpendicular and more time under the influence of the wings and the rear bodywork that it meant to stop takeoff at 180deg yaw.
I'll cite the Capello flight in which the car actually was spinning at a reasonable rate and once it had spun around it came back to earth pretty quickly.
Does this make any sense to anyone but me?

[MulsanneMike]

Originally Posted by Tom87

As you say - any large flat area parallel to flow on the underside will produce lift when combined with the aerofoil like curves on the top surface - so what about londitudinal strakes to distrupt the flow when pitched?

The IRL has tried something like that. If you look close there is a longitudinal strake, about 10mm tall, that must run the length of the car's center line. I'm not convinced of the results.

[AU N EGL]

If rules get too strict then LMPs will look like Grand AM DPs or worse, NASCAR CoT.

[Holt]

A car spinning by itself and then going airborne should not be acceptable in today's racing.

NASCAR has introduced many safety innovations over the years to counter spinning cars that go flying, roof flaps, restrictor plates to reduce the speeds from 220mph+ to 190mph on the larger tracks, tires within tires.

Sportscar racing can do something. They've seemed to have solved straight up blowovers, but now it seems that when the prototypes get sideways at high speeds they tend to get at least 2 tires of the ground and start to fly.

This may have bene acceptable in the past, but if sportscar racing doesn't want to be seen as the modern Roman Coliseum I suggest they do something about it.

From an amateur to the technical side of sportscar racing it appears the underside of the car is nothing but a large wing. A 333400kg jumbo jet can take off at 160mph. What happens when a 925kg prototype goes sideways at 160mph and the bottom of the car is nothing but a flat wing?

I believe that if the Peugeot's underbody had less surface area the car wouldn't have tilted over as much and it would have probably landed on it's 4 wheels after the initial takeoff and stayed put instead of flipping over on it's side again.

Why can't a roof flap type feature be implemented on the side pods. Or maybe have some sort of emergency device that opens holes at the bottom of the car when it senses that it is starting to lift to reduce the amount lift the underbody creates.

I'm not expert, but it's quite obvious something can be done

[ger80]

Is there a link to the low downforce car configurations?

[Purist]

The old prototypes (Ford GT40, Porsche 917, Ferrari 512) were and are considered to be notoriously unstable, so that doesn't seem like a good road to go down (low downforce/low drag). Even as far back as the 1930s, only a selct few drivers were ablt to REALLY handle cars that had a tendency to oversteer (the best were Rosemeyer, Nuvolari, and Stuck in the hill climbs).

You guys might want to check MulsanneMike's latest site update. Among other things, it mentions that critical take-off speed while going backwards (180 degrees yaw) has gone from 281km/h (174.6mph) with the LMP900 regs to 500km/h (310.7mph) with the LMP1 regs. However, critical take-off speed while going sideways (90 degrees yaw) has dropped from 282km/h (175.2mph) for the LMP900 regs to just 192km/h (119.3mph) for the LMP1 regs. That right there is the real problem. The LMP900s didn't have such a dramatic drop-off in downforce going through the various degrees of rotation.

I might also mention tha I'm quite certain that the Peugeot had lifted the right side off before it encountered the grass, and was dragging the left front tire on pavement the whole time before the car was fully off the ground.

Finally, I'll take another look, but I think the camera zoom made it look like the Peugeot was much closer to the top of the fence than it really was, so I'm not especially concerned about the cars clearing debris fences at this juncture.