Hi Paul,
As I was going to sleep last nite, I had a thought about the scatter in
the calculations. The speed is only being reported to the nearest
MPH. The actual speed could vary about +/- 0.5 MPH from that, and the
differences are only 1 to 3 MPH.
I took the data from the 2c run that you sent and plotted MPH vs t. I
then did a least squares fit to a second order polynomial and got this
formula:
MPH = 0.004242t^2 - 0.973316t + 80.010675
differentiate and we have
delta(MPH)/delta(t) = 0,008482t - 0.973316
so drag should be
3300/-32 * delta(MPH/delta(t)
(the minus 32 because it's deceleration or just to get a positive sign
for drag.)
Plot of the data, least squares fit, and calculated drag attached.
Drag is plotted against t, so to get the value for 50 MPH, move over
from 50 MPH till the speed plot is reached, then move up to the
calculated drag. I haven't kept track of the units, and may have left
something out.
Bob W.
--
http://www.bob-white.com
N93BD - Rotary Powered BD-4 (projected engine start in November)
Custom Cables for your rotary installation -
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I'll have to cogitate on that for awhile.
In the mean time maybe Jay can give us .1 MPH resolution.
What about that Jay?
Also in the mean time I have taken the simplistic brute force
approach and converted all the times to seconds.thousands of seconds.
I have attached my simplified spread sheet.
My question is how do I plot "C" as a function of "B".
Surely that can be done.
I went to Data > Data Plot but that is as far as I can get.
I'll go to the book store shortly and get an Open Office book.
Paul Lamar ...No rotor no motor.
I don't know what it is about Open Office but I used to be a whiz
on Lotus 123. How in heck to you get the same formula in
all the cells in one column? Something simple like D=C*88/60
I plotted the data manually it came came out with little scatter.
I'll scan it shortly when my other Windoz computer gets done rendering.
Paul Lamar ...No rotor no motor.
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