Okay, so watching the Rain in Spain Fall Mainly on Brazil today, I had a lot of time to think silly thoughts....

The exhaust pressure coming from an F1 engine must be pretty epic. And if, somehow, that exhaust could be vented out of the nose of the car onto the tarmac ahead, it could conceivably clear much of the standing water prior to the front wheel's arrival.

If, structurally, one could make these ducts run from back to front, there would be no weight penalty for what amounts to a void.

You would just need a movable piece to route the exhaust to the front. It would remove horsepower, but in the wet it wouldn't matter so much.

Could such a thing be legal? Practical?

Practical? Not even close.........start with the weight, then go to the disruption of airflow under the car, then........STOP THINKING!!!!!!!

Carbert - 17 October 2009 07:59 PM

Okay, so watching the Rain in Spain Fall Mainly on Brazil today, I had a lot of time to think silly thoughts....

The exhaust pressure coming from an F1 engine must be pretty epic. And if, somehow, that exhaust could be vented out of the nose of the car onto the tarmac ahead, it could conceivably clear much of the standing water prior to the front wheel's arrival.

If, structurally, one could make these ducts run from back to front, there would be no weight penalty for what amounts to a void.

You would just need a movable piece to route the exhaust to the front. It would remove horsepower, but in the wet it wouldn't matter so much.

Could such a thing be legal? Practical?

You offer an interesting idea, Carbert; clearly thinking way outside the box. Would aiming the exhaust out the front of the car and onto the road surface be legal? I don't know; the question has never come up. It might be, for awhile, given the FIA's typical bumbling over rule-making. But eventually they'd ban it.

Is it practical? No, for several different reasons:

First, as you point out, there would be some power lost as the exhaust gasses pass through a diverter valve, do a U-turn, travel through several feet of pipe and exit out the front of the car.

Second, you would have to run very hot pipes past temperature-sensitive things like electronics, radiators, assorted wires and hoses, the driver and other things that would go up in smoke and/or malfunction in the presence of +600° temperatures.

Third, as Wilmywood pointed out, the engine does pump considerable volumes of gas, which very well may screw up the under-car airflow if it is not aimed properly. However, there was a time, several years ago, when the exhausts were deliberately run out the bottom of the car just ahead of the diffuser to increase downforce, so it all depends.

Fourth, you're assuming the blast of hot air will be sufficient to blow water away from the tyres and/or evaporate it from the track surface. At 18,000 rpm, a 2.4 litre Formula One engine passes 21,600 litres of air -- about 736 cubic feet of air per minute, or 12.71 cubic feet per second. Those sound like impressive numbers until you consider that a Formula One car travels somewhere between 176 feet per second (120 mph) and 256 feet per second (180 mph). So if you divide that 12.71 cubic feet in half (one half per exhaust pipe), then by 176 feet per second, then you're only blowing 62.4 cubic inches of air per square foot of pavement. That's a cushion of about .43 inches of air. It's also about on litre of air per square foot; about the same amount a person exhails with each breath. Now, could you blow a square foot of pavement dry with one breath?

Think about it.

Now ask yourself this: how much energy does it take to vaporize water, and how long would it take for a 600° blast of air to completely blow away, say, 1/8 inch of water? I doubt you could boil water that fast, either. This, of course, ignores the fact that, in a rain storm, a considerable volume of rain will be falling on the track, replacing the water your system may or may not have evaporated and displaced. Even the "track drying" tubine engines used by Indianapolis Motor Speedway and others to blow the track dry, using thousands of cubic feet of 1200 degree air per minute, have to go slowly (44 feet per second or less) to dry the track surface after the rain has stopped. Mehtinks your little 2.4 litre Formula One engine might be a wee touch over-matched in a rain storm.

Fifth, you're assuming that the exhaust gasses pumped out by the engine will exceede the amount of air that would be forced into the pipe, at speed.

Okay, numbers time again.

a four inch diameter pipe has a cross-sectional area of about 0.087 square feet. Traveling at 120 mph (176 feet per second) and assuming all the air went into the pipe, that is 15.36 cubic feet of air per second being forced into the pipe by the car's motion. Given that we've already calculated the exhaust passing out of the engine is only 12.71 cubic feet per second (for both pipes), or 6.355 cubic feet per second for each pipe, you have a problem. At speed, the forward-facing exhaust pipe would act as an air scoop, taking in 15.36 cubic feet, while the engine is only pumpint out 6.355 cubic feet.

In other words, at 120 mph, the exhaust pipe would be taking in nine cubic feet per second more than it can pump out. Thus, you would be stuffing air into the engine through the exhaust!

Oops...

It was a nice idea and a good try, though.

Thanks for the considered reply, GreyWolf74. And thanks for taking it in the spirit in which it was intended. But I think there may be (especially since with both championships wrapped up today, ushering in the off-season - save for the question of whether the new Abu Dhabi is cool or silly), some points left to argue.

GreyWolf74 - 18 October 2009 09:58 AM

First, as you point out, there would be some power lost as the exhaust gasses pass through a diverter valve, do a U-turn, travel through several feet of pipe and exit out the front of the car.

But in the wet, you can't use all the HP anyway. The idea would be that there would be a selectable diverter valve (movable aerodynamics? Ehhh, there's an argument there maybe).

Second, you would have to run very hot pipes past temperature-sensitive things like electronics, radiators, assorted wires and hoses, the driver and other things that would go up in smoke and/or malfunction in the presence of +600° temperatures.

Yeah, well, those are design issues.

Third, as Wilmywood pointed out, the engine does pump considerable volumes of gas, which very well may screw up the under-car airflow if it is not aimed properly.

With a full-wet setup they're raising the chassis anyway.

Third, you're assuming the blast of hot air will be sufficient to blow water away from the tyres and/or evaporate it from the track surface.

Important point: Not evaporating. Not drying. Just blowing.

At 18,000 rpm, a 2.4 litre Formula One engine passes 21,600 litres of air -- about 736 cubic feet of air per minute, or 12.71 cubic feet per second. Those sound like impressive numbers until you consider that a Formula One car travels somewhere between 176 feet per second (120 mph) and 256 feet per second (180 mph). So if you divide that 12.71 cubic feet in half (one half per exhaust pipe), then by 176 feet per second, then you're only blowing 62.4 cubic inches of air per square foot of pavement. That's a cushion of about .43 inches of air. It's also about on litre of air per square foot; about the same amount a person exhails with each breath. Now, could you blow a square foot of pavement dry with one breath?

I don't think those are the relevant calculations as they doesn't take into account the speed of the airflow generated.

Volumetrically, we're only concerned with the contact patch(es). If it could only be done for the front tires, it would still be an advantage. But you've already pointed out that exhaust flow has already been harnessed to a useful degree for aero effects. The amount of the advantage would not have to be total and complete.

Fourth, you're assuming that the exhaust gasses pumped out by the engine will exceede the amount of air that would be forced into the pipe, at speed.

Ahh, but you appear to be assuming that there is a tube that is pointing forward, like a brake cooling duct. It would be anything but that.

You do make some interesting points, Carbert, but I stand by my calculatins. At 120 mph, the engine will be passing about one litre of gas per square foot, and covering that area in somewhere between five and six milliseconds -- or less, if the car is going faster. I'm not sure about the size of your lungs, but that litre is about what you'd breath out in an average breath. Even at five milliseconds, that's still not enough to blow the area in front of the front tyres' contact patch dry.

If it was sufficient volume in such a short time, you could cool your soup by blowing on it. Sort of. Then you'd have to clean up the mess from the soup blown all over the place.

Since you mentioned using this exhaust-drying system as a front-wheels-only proposition, that brings up another point: What about the rear tyres?

Assuming you could blow the track dry under the front tyre patches by aiming the blowers backwards from the front wing, you've still left the rear contact patches in semi-wet conditions. Or completely wet, if they're not precisely tracking the fronts. So... Lots of front grip (dry contact patches) combined with much less rear grip (semi-wet contact patches) equals oversteer. I'm sure the spectators would be amused, watching the cars "dirt-track" around the course, but the drivers may not be so happy.

Might I suggest aiming the exhaust at the rear tyres, instead? For one thing, the piping would be much shorter; you could almost do it by installing the manifolds back-to-front. Second, the rear end would be much better-planted, aiding accelleration, braking and cornering. Third, the soggy front wheels would result in understeer, which is generally less frightening than continually trying to keep the car from swopping ends.

Unless, of course, you lose the front end and go sliding forward into a barrier. (Ask
Jack Brabham about the last corner of the 1970 Monaco Grand Prix for his views on terminal understeer.) (wink!)

http://www.youtube.com/watch?v=XC2v4A_y4VI

(pay particular attention at around the 1:30 mark of the video.)

The main problem I see with this is that yes, the exhaust pressure is great, but wouldn't the flow of air at 150 mph plus, going into the exhaust be pretty great as well. The exhaust would be cooled by incoming air, and then as it left the pipes it would cool very quickly by the time it hit the tarmac. Second, running the hot exhaust pipes by the driver's tub would be uncomfortable at best.

However if you want to pursue this, why not have the exhaust exit under the car instead of on the top of it.

Since we are being silly, since Brawn was having trouble in colder weather getting their tires up to temp, they should have pointed the exhaust at the rear tires.

hellaciouss_craw - 19 October 2009 06:46 PM

The main problem I see with this is that yes, the exhaust pressure is great, but wouldn't the flow of air at 150 mph plus, going into the exhaust be pretty great as well. The exhaust would be cooled by incoming air, and then as it left the pipes it would cool very quickly by the time it hit the tarmac. Second, running the hot exhaust pipes by the driver's tub would be uncomfortable at best.

However if you want to pursue this, why not have the exhaust exit under the car instead of on the top of it.

Since we are being silly, since Brawn was having trouble in colder weather getting their tires up to temp, they should have pointed the exhaust at the rear tires.

exiting the exhausts under the car, just ahead of the diffuser, used to be done about five years ago. Exiting the exhaust just in front of the rear tyres may help keep things warm, but what happens if the engine blows? Oil coming out the pipe and onto the tyres can be, uh, a bit "messy."

I don't know if the F1 Sporting Regulations contain such a rule, however, most motorsports rule books contain a rule to the effect that the exhaust must exit the vehicle behind the drivers location.

You only have to review video of past NASCAR Races that were rain delayed and trucks with large turbines blowing hot exhaust air slowly circling the oval track to see how small the area the hot exhaust dried. It took hours of repeated passes to effectively dry the track. I realize that for is discussion drying the track is not the objective, I am just pointing out how small the affect of directing hot exhaust onto the track to over come the effects of hydroplaning.

It is my opinion that all it would do is to cause water turbulence and increase the affects of hydroplaning at the rear wheels, or float the car so the rear wheels lost traction with the track.

Racing in the rain in the distant past when F1 cars did not have aerodynamic wings, cars with wet weather tires could move water away from the car and maintain traction with the track to effectively steer and propel the cars to continue racing.

It is clear to me that racing will have to be red flagged and delayed once the rain continues to fall and flood the track.

Remember I said that it's not about drying the track. It's about blowing away just enough standing water that you can go just that much faster than cars not similarly equipped.

Having said that, I just saw where the Mythbusters concluded that a car with Golf Ball dimples actually showed an 11% improvement in fuel efficiency. So forget the redirected exhaust. It's all about the dimples now.

Carbert - 21 October 2009 09:15 PM

Remember I said that it's not about drying the track. It's about blowing away just enough standing water that you can go just that much faster than cars not similarly equipped.

Having said that, I just saw where the Mythbusters concluded that a car with Golf Ball dimples actually showed an 11% improvement in fuel efficiency. So forget the redirected exhaust. It's all about the dimples now.

I love Mythbusters...........now if only they were as good with science as they are with entertainment, we might learn something..........