wheel torque at aero limits
wheel torque at aero limits
(OP)
I've been able to determine that with a rear wheel torque of 322ft/lbs my speed limit is 207mph.
All factors being equal:
cross section 5.8385 f^2
cof. of drag 0.6
rolling resistance 0.02
air pres 2124.00424 lbs/f^2
density of air 0.07411 lb-mass/f^3
temp 77
How can I compute what the needed wheel torque is at higher speeds?
Yes all of thee are actual numbers, not a simulation.
All factors being equal:
cross section 5.8385 f^2
cof. of drag 0.6
rolling resistance 0.02
air pres 2124.00424 lbs/f^2
density of air 0.07411 lb-mass/f^3
temp 77
How can I compute what the needed wheel torque is at higher speeds?
Yes all of thee are actual numbers, not a simulation.





RE: wheel torque at aero limits
RE: wheel torque at aero limits
F=T*rr
F=1/2*rho*Cd*A*v^2+m*g*Crr
are the formulas you need, in consistent units.
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: wheel torque at aero limits
I do have the other two values.
weight = 762lbs
rolling radious = 12.1"
I'm still not sure where to plug these values into the formula you've given. Any help would be greatly appreciated.
RE: wheel torque at aero limits
cross section 5.8385 f^2=A
cof. of drag 0.6=Cd
rolling resistance 0.02=Crr
rear wheel torque of 322ft/lbs =T
density of air 0.07411 lb-mass/f^3=rho
weight = 762lbs =m*g
rolling radious = 12.1"=rr
speed limit is 207mph=v
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: wheel torque at aero limits
RE: wheel torque at aero limits
RE: wheel torque at aero limits
let's start with the OP ...
torque is ft*lbs, not ft/lbs.
by torque do you meaning braking toque ?
is "rear" wheel important (for some reason not immediately obvious)
and greg's response ...
i think you were beguiled by the OP's lb/ft, shouldn't it be T = F*rr
then F = Cd*(rho/g) ... because of the units 1lbf = 1lbm*g, or 1 lbf = 1slug*1ft/sec2 (don't you just love imperial units).
then why would the aero drag force act on the ground line ?
RE: wheel torque at aero limits
the rear wheel torque statement was just to identify the source of the number so that it's known that powertrain losses have already been subtracted from the flywheel brake torque
RE: wheel torque at aero limits
i thought "rear" as in tail-dragger (the tail wheel at the back of a plane).
i don't think greg's repsonse applies (but i could easily be wrong). greg gave you the aero. drag force for something whistling along at 200+mph, somehow i don't think that's what you've got ... maybe you could explain the set-up a bit more
RE: wheel torque at aero limits
currently I'm "stuck" at 303.6 ft/sec with 322 ft*lbs. I'm trying to determine how much ft*lbs I'll need at say 308, 311.67, and 315.33 ft/sec.
RE: wheel torque at aero limits
and T = D*V/(rpm*(2pi/60))
it's a bit of a different question as to whether this torque can be applied to th eground (without skidding).
RE: wheel torque at aero limits
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.