Well, well,
I am underwhelmed over the response to conducting an experiment to
determine the drag coefficient for our little bitty cars. Just remember, if
you don't
participate, you can't gripe. Sorta like voting. For those who want to help,
the following is the procedure to be used... Consider this as the data
acquisition form: print it out, fill it out during your test runs, hit the
reply button, fill in the data and send it back to me. I promise to keep your
names confidential to protect the innocent (well, maybe...).
Cut Here*********************************************************************
Optional data: Your name___________________________________
Would you object to having your name and your data associated with each
other and posted?
Yes [ ] No [ ]
NOTE!!!!!!!!! This Test must be run with zero wind! Do the test early
Saturday morning before you goto play golf or whatever!
1. Locate a straight stretch of road which will permit you to accelerate to
65 mph and then to coast down to about 30 mph without ticking off the other
road users or the Highway Patrol.
2. Drive your car around for at least 20 minutes to warm the tires to
operating temperature.
3. Make sure you have a passenger who can read and write. They will write
down the times as you call off the speeds during coast down.
4. Estimate vehicle weight. Wv = (put weight here) lbs
5. What is your weight? Wy = (put your weight here) lbs
6. What is your passenger's weight? Wp = (put passengers weight here) lbs
7. What is the ambient temperature? Ta = (put temperature here) degrees F
8. Estimate tire temperature. Tt = (put tire temperature here) degrees F
9.Measure tire pressures just before test and after warm up.
Left front = (put left front tire pressure here) psig
Right front = (put right front tire pressure here) psig
Left rear = (put left rear tire pressure here) psig
Right rear = (put right rear tire pressure here) psig
10. Measure from the center of the tire/wheel to the ground. This
determines rolling radius.
Left front = (put dimension here) inches
Right front = (put dimension here) inches
Left rear = (put dimension here) inches
Right rear = (put dimension here) inches
11. Tires are Radial [ ] Bias Belt [ ] Put X in
appropriate box
12. Tires are : Type in size as indicated on the tire. Include Mfg. NAme.
Front:_________________________________________________
Rear :_________________________________________________
13. Configuration of car: Tiger [ ] Alpine [ ] Put X in
appropriate box.
Rag top: Up [ ] Down [ ]
Hard top On [ ] Off [ ]
Tonneau On [ ] Off [ ]
Do you have front air dam on car Yes [ ] No [ ]
Differential gear ratio: Put gear ratio here DGr = _______________
Tranny gear ratio during coast down( data will be used to try and
determine efficiency)
Put gear ratio here: TGr = ___________
Speedo Correction: Over a measured distance (say 5 miles) does your
trip meter indicates
how many miles? I will use this number along with the measured
distance to calculate a correction factor for your speedo.
Measured distance = (put miles here)
Indicated diatance = (put miles here)
Add any other unique aspects about your car here:
14. What did you have for breakfast...pay attention. This was a trick
question!
15. Check weather. What is barometric pressure. Bp = (put data here)
inches Hg.
15a. What is your altitude? Alt: = ________________ if known. Nearest town
is:______________________
16. Ready?
a. Accelerate to 65 mph.
b. Put car in neutral
c. Keeping one eye on the road, call out when speedo hits 60 mph.
d. Passenger, write down time, including seconds.
e. Driver, call out when speedo hits 55 mph.
f. Passenger, write down time, including seconds.
and so on...
Test run 1.
Date:______/_______/_______
60 mph Time:_____________hrs: min: secs
55 mph Time:_____________
50 mph Time:_____________
45 mph Time:_____________
40 mph Time:_____________
35 mph Time:_____________
30 mph Time:_____________
Test run 2. Drive in the opposite direction, if possible, to remove
any bias.
Date:______/_______/_______
60 mph Time:_____________hrs: min: secs
55 mph Time:_____________
50 mph Time:_____________
45 mph Time:_____________
40 mph Time:_____________
35 mph Time:_____________
30 mph Time:_____________
L.E. Mayfield
124 Maximillion Drive
Madison, Al. 35758-8171
205-837-1051
DrMayf@AOL.com
mayfield@traveller.com <<<<preferred
"Thought is the software of the mind;
rational thought is bug free!"
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