14 replies to this topic

[dretceterini]

I am an engineer, but NOT an aerodynamicist. I just got a factory tape done 20 years ago on Matra. The 640 "flew" in practice and was destroyed, never to be rebuilt. I was just wondering why it flew...

With the bit I know, it looks to me that the nose of the car is just TOO blunt, creating too much downforce on the front end of the car. There is also no horizontal satbilizer on the car; only verticle ones on the tail (like the beautiful CD Panhard aerodynamic cars of the late 60s at Le Mans)

Thoughts please...

Stu

[irineos]

pictures please

[Bozothenutter]

hey stu
assuming the car had a flat bottom(as did the mercedes that went flying in'99) it might have been the same kind of problem, air getting under the car?
I found this page with some info:http://www.matraspor...types/M640.html
if you look at the picture of the car in profile, it does have kind of a aerofoilshape doesn't it?
hope this helps!
I also have the french matra book(la saga) if that is any help.

Sudesh

[Keir]

Nice looking car!!! The nose does seem to ride a bit high, that could have been one of the problems???

[dretceterini]

The Matra 640 had kind of a large wickerbill attached to the very trailing edge of the rear deck, attached to the corners of it by eye screw like divices..so the angle of it could be adjusted. It appears that it was fairly flat (maybe 20 degrees at the time of the crash) It appears that it was only about 4 inches tall..

The bottom of the car was not totally flat, as this was still a tube chassis car (kind of like a 917 Porsche)..I don't think a flat bottom was the problem. If you look closely, the nose is VERY blunt; perhaps too much so.

I have no idea how to post a photo, as there is no "upload" buttom on this site, like ones for e-mail attachments or to upload pictures of items to sell on e-bay..

..so Sudesh, I would appreciate if you would post one or two photos of the car...I think it is extremely good loooking...

Thanks,
Stu

[dmj]

Are you sure about CD Panhards in late '60s? Without checking I believe last CD Panhard was racing there in 1964 or 1965... But there vere later interesting "aerodynamic" French concepts, like Peugeot that was shown at Retromobile this year, and Alpine A220...ž
This Matra also reminds me of BRE Samurai (you'll finde some pics of this car in a thread of Japanese racing cars...)

[biercemountain]

My guess is that the Matra flew for the same reason that the old CAN AM cars did. Air would get underneath them at speed and they would simply "blow over". The same thing happened to the Mercedes at LeMans.

[dretceterini]

dmj

yes, there were CD Panhards at Le Mans in 1966 and 1967, along with a CD DKW in 1966, I believe. My friend Bruce Burness was involved with the BRE Samurai, and I just saw him a few days ago at the Society of Automotive Historians literature fair...I see him about 6 times a year...he is now involved in shock absorber design for a CART team, plus designing home furnishings and doing restoration work...he did quite a bit of stuff for Don Orasco's Scarab..and he still has his Lola T70 spider to do...

Stu

[dmj]

Stu, I presume you thought about DB Peugeot from 1966 race ? It raced with No. 53, was exposed this year at Retromobile and looks pretty like Matra. Or Panhard engined cars looked the same? Nice to hear about BRE Samurai history - that car was simply beautiful! A friend of mine think it is best looking racing car ever!

[dretceterini]

OOPs...as the kids would say "my bad" :

...as to the CD, yes, it was Peugeot powered and not Panhard. There was another very similar car with a kamm tail in '66 (I think, without pulling out the Le Mans books) with DKW 3 cylinder power.

Stu

[fausto]

A 640 replica has been recently recreated by former Matra employees, it was shown at Retromobile back in febraury.....on the february issue of AutomobileHistorique there's a very interesting piece about the car (both the original and the replica) together with an interview with aerodynamicist Robert Choulet, if someone is interested can pm me....

[SEdward]

Apologies for the quality of the scan, but here is a photo of the Matra 640 about to take off that was published in the February edition of "Automobile Historique".



Edward

[Henri Greuter]

If you watch the current breed of IRL cars, the upper surface of their side pods are also sloping down like on a airplane wing. That must require a lot of downforce by the wings to compensate for one would suggest.
It makes you wonder why at IRL they couldn't understand that Mario Andretti took off in April 2003 and and later on in the year Kenny Brack also got airborne. Not to mention Tony Renna , the kid who got killed in that Ganassi car

Henri

[Huw Jadvantich]

The newspaper clipping picture would tend to totally discard Choulets theory about the doors. They are absolutely flush, but the car looks as though it is very heavy on its rear tyres compared to the picture of it standing still, suggesting that it perhaps developed huge down force at the rear before the flip.

The 'bluntness' of the nose isn't necesarily an issue with regard to lift, unless it actually directs air underneath, similarly, the car doesn't necesarily have to have a flat bottom to act like a sail once enough of its area is presented to a 240mph wind.

[Arthur Anderson]

Originally posted by Henri Greuter
If you watch the current breed of IRL cars, the upper surface of their side pods are also sloping down like on a airplane wing. That must require a lot of downforce by the wings to compensate for one would suggest.
It makes you wonder why at IRL they couldn't understand that Mario Andretti took off in April 2003 and and later on in the year Kenny Brack also got airborne. Not to mention Tony Renna , the kid who got killed in that Ganassi car

Henri

Henri,

Not one of those drivers' cars got airborne entirely on their own. In each incident (such as Andretti's hitting a chunk of sudden debris in front of him, knocking the front end of the car upward), each car had something occur which let air get underneath the car at such and angle that yes, it did fly upward and through the air. In Brack's case, his becoming airborne and striking the catch fence pole at TX International Speedway as he did, was the result of his already being in an accident situation. Tony Renna's car, by all accounts got down into the infield grass, which is smooth only in photographs, but at 225mph plus, in a car with perhaps an inch or two of suspension travel, it too bounced upward, allowing airflow underneath the car at the wrong angle. No matter the downforce, and an IRL car has that in several thousand pounds at speed, it just can't counteract every possible sudden, virtually traumatic force.

The same thing happens in Nascar on occasion--again, almost always due to the disturbance of the attitude of the car in relation to the airflow around/over it.

Art