Chip

Having watched the Aussie GP yesterday I have a question for the technical among you.
Why is it that as the track temp goes up the lap times go down. I would have thought the opposite as when the tyre warms up it would soften and give more grip. Only reason I can think is as the rubber warms it softens it looses its lateral grip. Anyone know the answer.

Also has the camera man who films the podium ceremony drunk all that MOET champange. Looks like it as the shots of the podium are always really wobbly at every grand prix.

Chip.

pslewis

You have answered it yourself - more grip!!

Its the same reason they wiggle from side to side (its not the drunk scaffolder driving either!!) this warms the tyres see?

Pete

Dick White

hehe...j00 minkee

Warm Track = Warm Tyres = More Grip = Lap Times go Down.

Dunno about that shakes though

Chip

Pete,
I should have said lap times get slower as track temp rises. If there was more grip then surely they would go faster through the corners giving a faster time.

Chip.

RB5SCOTT

I thought that if the track temperature went up it would overheat the tyres, thus loss of grip.

Scott

DaveW

I thought it was down to higher temps mean the air is less dense so you get less power out of the engine.

DaveW

IWatkins

As track temps go up so the air becomes less dense. Less dense means less air molecules in the engine = less power. We all know that feeling. Compare cold morning against hot afternoon.

Also as the air is less dense, less air molecules exert pressure over the downforce surfaces so the level of downforce reduces. Again can be seen at airports. Some planes only just make it airborne on hot days. I did a study on this with RAF F4's years ago. Quite exciting measuring 5, 10, 50, 100, 200 and 300 cm air temperatures on runways as F4's are blatting past you on reheat

I would have also thought this second reason would have been outweighed by the increase in grip from hot rubber, but there again, I guess the tyres have a specific temperature window they can operate in and they simply 'go off' like any other tyre.

As for the pished camera man ? Well maybe he is a long way away to get a straight shot at the podium and is using a big zoom lense and that magnifies any shakes.

Cheers

Ian

DaveD

iTrader: (2)

I think Mr Watkins has given a perfect answer. It is probably worth remembering that the air temperature over the track can be well over 10 degC hotter than the 'ambient' temperature, and the road itself hotter still.

Temperature has a masive influence over the amount of power an engine can produce. Basically the hotter the air, the less dense it is, and the less power you can get for a specific volume. (this is why our scoobys have an intercooler to try to counteract the effect)

DavidRB

Curses! My secret is out!

GaryC

True...true - but why does track temperature increasing decrease lap times?

Take sunday's race compared to sunday morning's practise. Track temperature was higher, but ambient temperature was lower, and they 'expected' slower lap times than the practise because of track temp

IWatkins

Gary,

Not 100% on their reasons for thinking this other than the temp profile over a hot surface such as a race track.

Imagine the ambient is 20 degrees and the track temp is 35 degrees. Well you will get a mixing layer of air between the surface and X cm up that is almost at track temp because of the air being directly heated by the surface. As you get higher the temperature drops down to ambient. The height of X is all related to many variables such as wind speed, humidity, mixing, difference between ambient and surface, sun strength, time exposed etc.

There again, they may not be thinging any of this and may be related to the tyre compounds used.

Or, they always expect lower lap times from practice because practice laps are run with little fuel.

Or something

Cheers

Ian

DavidRB

Grip doesn't rise linearly with temperature, because the materials used (tarmac & rubber) suffer changes to their physical properties as the temperature rises. As tarmac gets hotter, it softens and some of its constituents (oils, etc.) start to melt and may come to the surface.

GP tyres reach their optimum grip at around 125°C, which is pretty hot, so it's easy for them to get overheated when the track temps rise by 10°C.

To this, you have to add the effect the hotter air temperatures (a hot track has hotter air sitting on top of it) have on the ground-effect aerodynamics and the engine.

cullenj

[QUOTE]Originally posted by DavidRB:
[B]Grip doesn't rise linearly with temperature, because the materials used (tarmac & rubber) suffer changes to their physical properties as the temperature rises. As tarmac gets hotter, it softens and some of its constituents (oils, etc.) start to melt and may come to the surface.

Martin Brundle made a comment to that effect just before the race got underway.