you've figured most of it out for yourself already. if both cars have
the same speed through the turn, then the heavier car must achieve more
lateral grip. And if both cars have the same speed through the turn they
are both pulling 1G = 32ft/sec^2 (note mass of the car is irrelevant).
It may help to recall that lateral acceleration can be calculated on a
skid circle by G = (V^2/radius)/32.2 where V is measured in ft/sec and
radius is in ft.
Dave Yeung
"rocket scientist"
Houston Texas
On Fri, 19 Nov 1999 10:41:28 -0500 dg50@daimlerchrysler.com writes:
>
>
>I've been tossing this problem around in my head for the last couple
>of days -
>I've got the concept, but I'm having trouble putting an equation on
>it.
>
>It's pissing me off - I know this stuff, dammit!
>
>Anyway, here it is:
>
>You have 2 cars at a ProSolo.
>
>Car A weighs m, and puts out f ft/lbs in a perfectly flat torque
>curve.
>Car B weighs 2m, and puts out 2f ft/lbs in a perfectly flat torque
>curve.
>
>Both cars have identical gearing/tire diameter such that Car B is
>putting out
>twice the thrust as Car A. For purposes of this problem, we assume
>that the
>thrust is the same as the engine torque (yes, I'm mixing units - I
>don't care.
>Car A has a thrust of f, Car B has a thrust of 2f)
>
>Given that acceleration = force/mass, and given that Car B has 2f and
>2m, we
>determine that f/m = 2f/2m So in other words, both cars accelerate at
>the same
>rate.
>
>At the end of the straight, both cars are travelling at an identical
>velocity V.
>Immediately following the straight is a turn with radius R.
>
>Now both cars may be travelling at the same speed, but Car A has a
>momentum of
>mV, whereas Car B has a momentum of 2mV. In order for Car B to
>maintain the same
>speed through the turn as Car A, it must either be capable of
>maintaining a
>higher lateral acceleration. (Or is the lateral acceleration value
>uneffected,
>but Car B needs more lateral grip to maintain that acceleration?)
>
>How much higher?
>
>If both cars are capable of maintaining 1G laterally, and both cars
>have the
>same amount of grip, then Car B must slow down. By how much?
>
>Anybody have the solution?
>
>DG
>
>
|