BMW flip

[Spiteful]

Right

[Félix]

Last year in practice for PLM the Champion R8 had a moment when a wing endplate failed or something like that: it spun and lost its engine cover, part of the car left the ground when sideways and the whole rear overhang was trashed.

Well, it happened today to Miracle's Courage when it lost its engine cover due to contact at about the same place (2/3 of the straight). The new aero rules made it stay on its 4 wheels, and the rear vertical structure seems to have worked in slowing it down. The only problem is that the rear hood knocked off the vertical endplates (supposed to stabilise the car in spins). The car looked quite easily repairable.

[jross427]

I think the reason was that none of these cars ie Porsche GT1, Mercedes CLR, and the BMW v12 was the cars had such a low front plane and no front diffusers i think. i know the low front plane had some thing to do with it. remember in the wind tunnel, there is no simulater of the draft unless you make one, but when ur in the draft, it because the car in front of u already dirrected the are to its benifit (downforce), so theres no are for your car. all these accidents happend while cresting a hill in the draft sooo....... this is what i think might have been the problem

[rustyfan]

Originally Posted by jross427

I think the reason was that none of these cars ie Porsche GT1, Mercedes CLR, and the BMW v12 was the cars had such a low front plane and no front diffusers i think. i know the low front plane had some thing to do with it. remember in the wind tunnel, there is no simulater of the draft unless you make one, but when ur in the draft, it because the car in front of u already dirrected the are to its benifit (downforce), so theres no are for your car. all these accidents happend while cresting a hill in the draft sooo....... this is what i think might have been the problem

Yeah that's a pretty common theme when it comes to blowovers (i.e. "dirty air" while being behind another car). The same phenomenon can be traced back to the 70's and 80's as well where, for example, Mark Donohue had a blowover at Road Atlanta in 1972 and Cloude Gou had one at Lime Rock in 1983. Donohue's wreck was probably somewhat similar to Alboreto's, in the sense that his car landed upsidedown on the grass and tore itself to hell. Donohue was very lucky to survive that one.

[ss_collins]

illustrated by Eric van de Poele's huge test crash in 2002, where he flipped the Bentley at Paul Ricard, which he walked away from.

Does anyone know any more about this - was it a blow over?

[rustyfan]

Originally Posted by ss_collins

illustrated by Eric van de Poele's huge test crash in 2002, where he flipped the Bentley at Paul Ricard, which he walked away from.

Does anyone know any more about this - was it a blow over?

A sideways one, yeah. Here's a piece posted online on April 23rd, 2002:

Eric van de Poele was at the wheel of his Bentley EXP Speed 8 when it became airborne at the end of the mile-long Mistral Straight on Monday night as the team carried out its preparations for Le Mans at France's Paul Ricard circuit. The car slewed sideways, took off and caught the top of the guard rail before coming to rest upside down against a small outside retaining wall.

Van de Poele walked away from the wreck unaided, was not taken to hospital and continued driving the team's second car on Tuesday morning.

A brake problem is believed to be the reason for the accident, which began at the point on the circuit on which the car hit 200mph. A puncture has been ruled out as the cause.

Van de Poele said: "As soon as I hit the brakes the car went to the left onto the kerbs, went sideways and flew."

But he ruled out the accident as one comparable to those which have affected Porsche, Mercedes and BMW prototypes which flipped in a straight line in the past four years.

I've seen a few other reports which described the accident a bit more detailed, suggesting it flipped several times before coming to rest. In any case, it was probably somewhat similar to how Andrea Scheld flipped his Porsche 911 GT1-98 during practice at Homestead for the 1998 FIA GT round there:

[GTRMagic]

I thought the mega sports car flip was Mark Webber's twins and Peter Dumbreck's similar version at Le Mans... a loooooong time ago it seems now.. so Last Century

But caused by some interesting things it seems....

There are complaints in many major open wheeler series that as soon as a chassis comes behind another vehicle in the race, the car in front sucks away all the downforce, making it difficult for the car behind to follow for any length of time.

This is especially true of sportscars, where there are so many underwings and aero tweaks and twiddles you dont see... and some you do, like the massive vortex generators that come out the back of the cars, creating some of the enormous downforce a thoroughbred race car develops.

But there are always downsides to using all the air around you to develop downforce. The air has to come from somewhere... to suck the air from the front over and under the wing... the exit path needs to be considered.... where does all this "used" air end up?

Well in some cases it leaves a huge gust of wind coming from the back of the cars... but in others, the efficiency is such, that air isnt wasted, and is instead diffused in different directions at the rear of the car, such that any cars following are at a disadvantage in terms of being able to suck along in a slipstream, and maintain a level of comfortable aerodynamic downforce.

It has been suggested that the cause of Mr Webber and Mr Dumbreck's crashes were not necessarily due to a design flaw in the Mercedes sportscar they were driving... more that the air in front of them got sucked away by a car they were trailing, instantly losing the downforce on the nose, allowing the tyres to lose grip with the surface, a rise in ride height, as the air then got underneath the car, and flipped it into the air.

Not once. Not twice. But three times.

Plausible theory... but it is said that some teams purposely tell their drivers not to follow particular cars in practice/qualifying/racing as this exact scenario is played out, where aerodynamics play such a role in getting the speed out of a racing car, the loss of efficiency and balance in a trailing car can cause it to lose grip, and the driver to therefore lose control.... sometimes with graphic consequences..

I know we all laugh at "Days of Thunder" but one quote really stands out.... "Control is an illusion, you infantile egomaniac. Nobody knows what's gonna happen next: not on a freeway, not in an airplane, not inside our own bodies and certainly not on a racetrack with 40 other infantile egomaniacs" Dr. Claire Lewicki, Days of Thunder....

What works in theory sometimes works at the race track... the magic involved is understanding why something works, or it doesnt... and how it interacts with all the things around them

I can recall a locally built sportscar run in a late 1980's WEC event in Australia... the car was designed for medium to high speed circuits, developed to some extent, but not really on the aero side. The same driver (an openwheeler ace of years of experience in Formula cars and Group 'A' and V8Supercar) ran this car in most of its events. Until one day, they took the car to Phillip Island... which must rank as one of Australia's quicker circuits, with a huge dependence on aerodynamic downforce to achieve grip, and therefore speed.

Well this car had never been so quick in a straight line in its life. It shimmied, it shook, it wobbled, it dribbled... the driver got out of the car and thought it had broken in half! But it wasnt that at all... more that the aerodynamic aids on the front and rear of the car worked too well, they generated too much downforce relative to what was required, and the car generally felt spooky to drive... it was dangerous in this form, and without the necessary equipment to modify the panelwork, the car was pretty much packed away... and never saw service at that circuit again....

Aero a black art... but stuff it up... and there are major consequences....

[ss_collins]

Mods I think this should be in racing tech.

[fangio]

As far as I remember, Mercedes used a system at Le Mans that made the car lower itself at the back at high speeds in order to lower the wing angle.
Thereby there was less drag and thus a higher speed.
However, a lower back means that the nose goes up, especially with the long overhang.

This system probably didn't pose problems at tests where there maybe was no slipstreaming and there were no uphill parts.
At Le Mans, the lower back, following other cars and going uphill changed all that.

If you crash a car that way several times it's a design flaw, nothing else.

[GTRMagic]

Other teams had similar systems in their cars at the same meeting, and didnt flip into the woods... I think there is more to the cars they were following than meets the eye...

It would be interesting if the trainspotters among us take a squiz at the footage before the crash, and see if there is a certain Japanese car near the Benzes immediately before AirBenz took off in each case

[jhansen]

A good theory, but:

http://www.mulsannescorner.com/benzCLR1.html

As this pic shows no red and white car in sight.

[skycafe]

Originally Posted by XJR14/WSC95

I think Both the Road Atlanta incidents happened at the same part of the track.

Interestingly, if you saw yesterday's ALMS race, the Miracle Courage lost its rear deck, taking the wing with it, after cresting a rise. It had been tapped somewhat earlier, which must have damaged some fasteners. As it crested and then plunged I am guessing there was a temporary change in pressure over the rear deck, from lots of downforce to momentary negative pressure, which allowed air under and then boom, that was it for the rear. This happened also at Le Mans years ago to Eleseo Salazar, I forget the car, but he came over the Mulsannes hump and the rear bodywork just exploded off the car.

This instability has been around a long time. The original Lola GT and then the GT40 both having had front lift problems. The Can Am and Son of Can Am both sent several cars over, and the the IMSA GTP had more then one. I have seen a picture of a March that flew but never flipped, and then Morton's accident at Lime Rock.

I still feel that the Mercedes Flying Circus Act, having followed Porsche flips and preceeded the BMW flip at Road Atlanta, which all saw lots of airplay around the world in the major media, did nothing good for keeping the manufacturers involved in Sports Cars. Spend big money and risk that happening to ruin your investement in good publicity? Also, thankfully none of these episodes has sent a car flying into a spectator area, which would have an even bigger effect these days then 1955 Le Mans had on racing afterwards.

I am hoping the latest aero rules will stop these issues, and if my thoery about the fear of flying in the world press is correct, then give the manufacturers the confidence to become involved in prototypes. If I want to see aero stunts I will watch the airplanes do them instead of sports cars.

NASCAR continues now to battle a somewhat similar problem. Those cars float either side on or backward-amazing given the weight of the things. NASCAR is battling it so hard because unfortunatly, at a super speedway, when one of those things starts to float it is headed towards the crowd. They have dealt with it with pop up roof flaps and side windows. The fact that one of those hippos can take off makes one pause when looking at a little bitty sports car, that weighs only a bit more then half as much.


robert.

[jross427]

no sorry to say the mircale incident was at the end of the straight, the hill in the middle of the straight was much bigger till the accidents, then they shaved the hill. the porsche incident above had to do part in which of the unlevelness of the grass, kick one side up and air gets under it and ur in the air, remember Elliot Sadlers flip last year at talledage, for the same reason, got into the grass and it acted like a ramp.

[skycafe]

No, the Courage lost its rear bodywork at what is called turn 9, which is up the hill from Turn 10A, the left hander. 9 is the slight right bend that falls away down to the 10a/10b complex. The rear suspension was not broken until the car spun into the barrier on driver's left. The tire appears intact even after that impact and during the spin after losing rear deck and wing (wing was ripped off by departing deck). I made no intention of saying that the crest there caused this alone, it was the earlier impact the broke the fasteners. The change of pressure over the deck caused negative pressure that allowed the deck, losened by the earlier impact to part ways. Never meant as example of a purely aero flip like Porsche at Petit or the Mercedes at Le Mans, or even Hulme's M20 at Road Atlanta in '72, just to highlight the changing of pressure over crests.

I do agree 100% regrading the Porsche flip at Homestead. The flip is caused by 'tripping' on the grass verge, the car goes over wrong for aero.

[jross427]

o sorry, i thought u where trying to compare the two accidents, my bad, im really sorry, and if u look at the pictures that jhansen gives the link to, the very first one you can see the complete bottom of the car, and in the front part it is completly flat, if im not mistaken, one or two years after that, didnt they mandate a front diffuser?

[rustyfan]

Originally Posted by skycafe

NASCAR continues now to battle a somewhat similar problem. Those cars float either side on or backward-amazing given the weight of the things.

Stock cars have been going airborne ever since 1975, when Richard Brooks went airborne and flipped down the Talladega backstretch.

The flaps, developed by Roush Racing and NASCAR in 1993, are designed to disturb the airflow over the roof that creates the lift when a car is turned around, in order to keep the car grounded, but unfortunately said flaps don't always work if the car gets turned around fast enough (i.e. Elliott Sadler at Talladega in 2003), or if the car gets pushed sideways or backwards (i.e. Tony Stewart at Daytona in 2001).

In regards to Sadler's flip in 2003, while the grass played a small part in it, the biggest reason the car took off was, as mentioned, that it got turned around so quickly.

[pink69]

jhansen, can you post the Auberlen flip form PLM please cause I've never actually seen that one yet. Cheers.

[jhansen]

Just send me a private message with your email address and I will try and send it out later today.