Re: A few idle F1 questions


"Dave Baker" <Null@xxxxxxxx> wrote in message
news:ftrhbg$9om$1@xxxxxxxxxxxxxxxxxx

1) If you run your hand over the paintwork of the Ferrari F1 car does it
feel like sharkskin?

No, it's a smooth, greasy, unctuous texture, almost unpleasant to the touch
but above all cold. A cold so intense it burns and starts to claw greedily
through your hand and into your arm, sucking the heat and lifeforce out of
you as you sense a glimmer of the presence deep within the beast. As you
start to snatch your hand away a sibilant voice whispers suddenly in your
ear "Mi scusi signore" and you turn to see a tall dark pallid figure that
has somehow appeared noiselessly at your shoulder. Black clothes, black hair
slicked closely to the skull and dark lifeless eyes that seem to bore
through you as it wags a pale gaunt finger admonishingly at you. Startled
you make for the door and the figure escorts you out, gliding silently just
behind you but stopping short of venturing into the light.....

2) Which has more dimples?
a) The 2008 Mclaren F1 car
b) A Callaway HX golfball
c) DC's chin

DC's chin

3) A current F1 car sets off from rest in a 0-200 mph drag race. At what
speed (mph range) during this period is it accelerating fastest and why?
Why is this different to the behaviour of a normal road car?

Off the line its acceleration is limited by mechanical grip to the
coefficient of friction of the tyres which means about 1.2 to 1.3 g. As
speed rises so does downforce and the driver can use more of the engine's
power until acceleration peaks at about 85 mph at 1.75g. Above this speed
drag starts to sap acceleration but even at 160 mph the F1 car is still
accelerating as fast as a hot hatchback gets off the line.

A road car without downforce can't accelerate faster than it does off the
line.



4) A current F1 car does an emergency stop from 200-0 mph. How does the
rate at which it is scrubbing off speed (mph per second) vary during this
time and why?

At 200 mph the drag is so huge the car will decelerate at 0.9g just by
lifting off the throttle - about as fast as a road car can manage at best.
Downforce of twice the car's mass triples mechanical grip to give a
retardation rate of a further 3.8g or 4.7g in total. Nearly five times what
a road car can do. At 200 mph under braking the F1 car is scrubbing off
speed at the rate of about 100mph per second. As speed falls so does
downforce and drag and the deceleration rate slows. 3.2g at 150 mph, 2.2g at
100 mph, 1.5g at 50 mph.


5) How does 4 compare with the rate at which your own road car scrubs off
speed?

A road car without downforce is limited to about 1g at best on state of the
art road tyres and this varies little with speed because drag isn't a
significant factor compared to the vehicle's weight.



6) How much of a current F1 car's total suspension travel is in
a) the actual suspension?
b) the tyre sidewall?

Front maybe 30% to 50% in the tyre and much lower at the back which has more
suspension travel.


7) A theoretical F1 car weighs 605kg, has 1cm static ground clearance and
develops a further 1200kg of downforce at 200 mph. Use this information
to calculate the minimum suspension spring rates it must use to prevent
the chassis bottoming out at top speed.

Total wheel rate for the four wheels is obviously about 1200kg per cm or
6700 lbs per inch - about 25 times stiffer than a road car's suspension for
the same vehicle weight.



8) Is it possible for an F1 car to enter a corner such that at a certain
speed it loses adhesion and slides off the track but if the driver had
gone faster it would actually have made it round the corner? If so why?

No. That would imply all sorts of strange things about the laws of physics.


9) An average family saloon has five gears, does about 120 mph and 1st
gear is good for about 35 mph or 30% of that. The next 4 gears fill the
remaining 70% of the speed range. A current F1 car has seven gears so 1st
should occupy a smaller percentage of the total speed range than a family
saloon's 1st gear. How much of an F1 car's speed range does 1st gear
actually take up and why?

The power to weight ratio of an F1 car is so great that 1st gear can be very
high and still generate enough torque to spin the rear tyres off the line.
In fact 1st is good for about 100 mph or 50% of the vehicle's speed range
and it take about 3 seconds off the line to use all of this. The remaining 6
gears occupy the second 100 mph in increments of less than 20 mph each and
for the first few of these at least take less than 1 second before another
gear change is needed. If it wasn't for downforce 1st gear could be even
higher without sacrificing acceleration. Theoretically an F1 car can spin
the tyres off the line if 1st was geared for 140 mph which is about what 4th
is actually geared for.


10) Under what conditions is an F1 driver experiencing the most g force?
Acceleration, braking or cornering? How does this vary with car speed? How
do the figures compare with what you experience in your road car?

A road car can never manage more than 1g of force in any direction because
this is the limit of the mechanical grip of road tyres. Braking will use the
tyres slightly better than cornering and acceleration is a big variable
depending on power to weight ratio. With downforce an F1 car achieves 4.7g
under braking at high speed, 3.5g in corners at high speed and at best 1.75g
acceleration at about 85 mph.
--
Dave Baker
Puma Race Engines


.

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