Ralph, List:
I agree w/ Ralph-- his response is the definitive argument against measuring
windspeed and adding or subtracting from the reported speed:
The effect of windspeed (on trap speed) will vary with the CdA of the
vehicle, and so the system simply couldn't be fair to everyone.
As the "clueless" newscaster used to say on Saturday Nite Live-- "never
mind."
Russ, #1226B
p.s.-- as some other responders pointed-out-- variations in windspeed are
such a small factor in current International LSR trap speeds that they are
not a credible (sorry, Jack) argument for 1-hr turnarounds.
-----Original Message-----
From: owner-land-speed@autox.team.net
[mailto:owner-land-speed@autox.team.net]On Behalf Of Ralph Forsythe
Sent: Saturday, April 19, 2003 12:07 PM
To: land-speed@autox.team.net
Subject: RE: 1 hour turnaround time
>Date: Wed, 16 Apr 2003 08:08:53 -0500
>From: "Russel Mack" <rtmack@concentric.net>
>Subject: RE: 1 hour turnaround time
>
>W/resp. to wind-- I suggest that we could record wind direction and
velocity
>for each run (we already have the electronic weather stations), and solve
>the course centerline vector windspeed equivalent; add or subtract that
from
>the actual timed speed on each run-- even before the timeslip is issued.
This would be good except that it doesn't take aerodynamics into the
equation. 15mph of wind resistance to one vehicle is not the same as 15mph
of wind resistance to another.
I think if this involved aircraft, your idea would work since their speed
is purely relative to the air velocity around them (hence why on a flight
plan you correct for winds)... However in a wheel-based vehicle the speed
is only relative to the movement of the ground beneath the car; wind just
provides a little extra influence. With some of the more streamlined
vehicles, or even the smoothly-shaped newer cars these days, it would take
a significantly higher windspeed to equal the same amount of resistance as
it would on a brick with wheels.
Short of wind-tunneling everyone's car, or breaking out complex CAD models
with CFD analysis to obtain Cd values, there is no accurate way to measure
the complete influence of wind on a vehicle. Hence the short turnaround
time for cars, to minimize the chance of a dramatic wind shift. I suppose
that's where the time got doubled for bikes too, since the windspeed would
have a lot less impact on those, so they can get away with some more time
to tinker.
That's just how I see it anyway...
- Ralph
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/// what is needed. It isn't that difficult, folks.
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