Stopping from 300 mph without parachutes

[Franklin]

Even with brakes only on the rear wheels and low pressure slicks that tend to bounce, Top Fuel drivers have shown in an emergency they can stop a Top Fuel car from 300 mph on brakes alone. Funny Cars with four-wheel brakes and plenty of weight on the front end do have an easier time of it. Jet dragsters are the most dependent on parachutes since they typically run without wings and so have much less drag and little downforce.

[KC]

Another thing to consider, top flight drag racing machines do not use any engine braking to slow them. This would damage the engine as they rarely can run for longer than the alloted time to warmup and race without scavenging out all of their oil or getting fuel erosion on the pistons.

Also, consider that the NHRA sanctioned drag racign facilities have a minimum length shut down area to allow these guys to get the car slowed down even without a chute. Even now, the NHRa is looking at changing the rules as the top fuel rails and funny cars are becoming fast enough to outrun the track area if something goes wrong. No one wants to see Force win another race with a burning tube framed wreck at the end.

[Peter Mallett]

Originally posted by Franklin
Even with brakes only on the rear wheels and low pressure slicks that tend to bounce, Top Fuel drivers have shown in an emergency they can stop a Top Fuel car from 300 mph on brakes alone.

Yes. They have.

[Crash Test]

Then again i've seen several drag cars wind up in the next postcode (seriously)....whoopty doo..

[Franklin]

For those upon whom subtlety is lost, the implication was when cars that aren't even really built for maximum stopping capability can in fact come to a dead stop from 300 mph in a distance of about 2,000 feet it makes the logic behind those two chicanes on the Mulsanne straight even harder to fathom.

[KC]

I do not care for the chicanes along the Mulsanne, but they are not there just to test brakes and force the teams to changes rotors and pads. Speeds had gotten too high. Speed differentials were too much between the GT1/LMP classes and GT2/GTS cars. How would you like to hit the back of a Viper going 220mph when you are going 260mph in an Audi R8 LMP? At night? The Mulsanne used to be the most dangerous piece of motor racing real estate in the world, especially at night, until the introduction of the two chicanes. Sure, no one really likes them, but no one likes the chances of having an unlimited straight away either. The chances of making it down it in one piece are not good.

And before you [Franklin] break out with some take on LSR cars or drag racing cars going faster, none of them race in the dark with nothing more than their headlights to show the way. That is part of the mystique of LeMans. It is not LS records attempt racing or drag racing.

[TimD]

The chicanes are not universally popular, it has to be said. Derek Bell, in particular, has been very outspoken on the subject. He pointed out that there are now two more moments of stress on brakes and drivetrain per lap, whereas before, paradoxically for the sheer speeds involved, the old Mulsanne was a comparatively relaxing time for the driver.

I think (Mulsanne being public highway) that the road layout for an intersection means that like it or not, one of the chicanes will be there for keeps.

[ma]

Frank:

So are you now advocating that dragsters get rid of the parachutes since they aren't necessary ? Gee, and just a while back you insisted that they were a great idea for CART cars !

Make up your mind !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Oh yea, the Mulsanne straight also has some quick elevation changes - the type that can get a car to fly if an aero mistake is made, as Mercedes found out to their embarassment. The flight time would have been a record if the cars was going any faster, but that isn't what LeMans is all about !

You really need to get a life.

[Franklin]

"So are you now advocating that dragsters get rid of the parachutes since they aren't necessary ? "

It seems, MA, that neither reading between the lines nor taking a statement at face value are your strong suits. So exactly what are you good at?

[ma]

No, the problem is that you seem to have conveniently forgotten your own, somewhat boisterous, arguements from previously !

I will say though, you do keep managing to give us a good laugh. Maybe on second thought you should stay - we can use the amusement !

[yelwoci]

I think we should stop giving any credibility to some of F. comments by replying to them and then perhaps he stop swamping this forum.
I can't work him out as he seems to be full of information but zero assimilation. Perhaps he's reciting froma book when he gets home from school.

To suggest that a 300mph dragster stopping once in an emergency has any comparison with Le Mans, or for that matter my Jap tin box racer, beggars belief.

Just look at the verbiage input here, but I don't think he understands any of it, except to personnally abuse people.

So I recommend that we all desist from replying until he has something interesting to say!

:-(
IanC

[Franklin]

"Oh yea, the Mulsanne straight also has some quick elevation changes - the type that can get a car to fly if an aero mistake is made, as Mercedes found out to their embarassment. The flight time would have been a record if the cars was going any faster, but that isn't what LeMans is all about !"

Yeah, the two chicanes on the Mulsanne slowed the cars down so much that eleven years after the Peugeot attained 252 mph on the Mulsanne, the Mercedes designers couldn't even figure out how to keep a car on the ground at 180 mph.

[ma]

Naaa - it's too much fun watching Frank get all wound up when he's shown to be an idiot !

Frank:
Yep, even the best make mistakes once in a while. Too bad guys at your level (bottomfeeders) don't seem to be able to admit when they are wrong.

You still haven't answered about why you've changed your tune !

[yelwoci]

ma,
There was a great article in RaceCar Engineering (I'm just a subscriber not in the ad dept!) describing how Merc got it wrong by having too great an overhang from the front wheel centre line.

I think that he worked out that the bumps before the crest caused a 15mm lift of the front splitter which reduced its downforce a bit, but when it was immediately followed by a 15% gradient caused a significant change in the angle of attack of the front surfaces which dramatically reduced downforce and caused the car to rise further on the springs....negative feed back loop...eventually the splitter acted as a leading edge flap and the car took off.
All this happened within 50m at close on 200mph and would only happen at that particular place and on that circuit.

Pretty unlucky.
The MERC engineers I believe had tried to increase the effective downforce by increasing the lever between the splitter and the spring platforms.
But at least no one was hurt (miraculously) and everyone has learnt something.

Paul Valkenberg wrote the article I think.

IanC

[ma]

Read that article - pretty good. Amasing how such a seemingly simple thing can have unforseen, disasterous effects ! Just goes to show a bit of the complexity of the operating envelope that these engineers have to work to. The biggest problem that sometimes has to be overcome is the reletive lack of experience of younger engineers. I'd bet good money that most of them totally forgot that essentially the same thing happen a couple of times back in the old Can-Am days. Probably no one on the aero staff was around at that time! They certainly won't forget again !

[Slowcoach]

Perhaps Franklin should offer the Mercedes engineers use of his dragcar parachutes , and remarkable engineering expertise.....

[yelwoci]

MMMMEEEEEEEOOOOOOOWWWWWWWW

Slowcoach.....I like it!

[Franklin]

Yelwoci,

"I think we should stop giving any credibility to some of F. comments by replying to them and then perhaps he stop swamping this forum. I can't work him out as he seems to be full of information but zero assimilation. Perhaps he's reciting froma book when he gets home from school."

I cannot help but point out that MA is the genius who yammered on and on and on with the BS quoted below while in complete ignorance of the fact that the Arrows F1 team is currently using such a system. And the fact you have completely failed to say anything at all about how MA has been full of **** leads me to suspect you're even lower on the list than MA of people in a position to say anything at all about someone else's credibility.

"Pullrods were tried & discarded many years ago for many reasons : hard to get high enough motion ratios in such a confined space, upper a-arm has to be much beefier ( an unsprung weight disadvantage, which adversely affects mechanical grip, as well as much more prone to damaging the tub in a crash), the lower a-arm also has to be beefier to take the cornering loads, and the shocks are almost impossible to get at for easy adjustment, and usually run hotter because of the confinement. Been there, done that, threw away the t-shirt."

[ma]

As I said, it's too much fun watching Frank make an ass of himself, as he seems to insist on doing again ! How many places has he now reprinted his Arrows stuff ? And done so in a completely beligerent manner ? Gad, this guy is fun !

We love you Frank ! You are too good to be true !

Note: Pullrod rebuttal posted elsewhere as Frank isn't worth the time to reproduce it again.

[Franklin]

"Ever hear of the Mercedes C111 ?( yea, I expect to be loudly corrected if my memory isn't perfect !). It ran on the Merc test track for 24 hours at 220 on only 195 HP ! Which means that they could have run up around 440 with only 800 hp or so. Might be a problem finding the tires to do that for 24 hours though."

MA,

You've probably discovered by now that a lot of people get belligerent with weasels who when they make huge bonehead mistakes that show complete ignorance of basic aerodynamics, actually expect the rest of us to buy the lame excuse of "That's not what I meant to say."