R/C Tech Forums - View Single Post - Dyno, Homemade, Using a Novak Sentry Data Logger, Continued, The Experimental Thread.
Old 04-16-2009, 06:32 PM
  #37  
SystemTheory
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Join Date: Mar 2009
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Attaching a new sketch of Oval versus Road Racer Run Lines

Estimated Flat Turn Velocity and Time
R - turn radius in feet
S - segment length in feet
aC - centripital acceleration in g's
g - 32.174{ft/s/s} standard gravity

v = SQRT(aC*g*R) velocity {ft/s}
t = S/v {s} time through constant radius segment at specified aC

Oval Turn Study
R = 15.81{ft}
S = 49.6{ft}
ac = 3{g's}
v = 39.06{ft/s} = 26.56{mph}
t = 1.27{s}
2t = 2.54{s}

And if speed is constant 39.06{ft/s} in the straights
then Total Lap Time = 3.76{s}

If the line geometry is correct and this lap time is too small, aC is too large.
Some time would be added for braking segments.
Some time would be subracted for acceleration segments in the straights.

Road Racer Turn Study
R = 10.99{ft}
S = 24{ft}
aC = 3{g's}
v = 32.57{ft/s} = 22.15{mph}
t = 0.74{s}
2t = 1.48{s}

This car must punch out of the slow corners more aggressively.
An acceleration model requires a Dyno curve matched to the driveline.

John, it's not clear to me the power available on the track versus Dyno for 17.5, 13.5, and 3.5 motors. I'm assuming all curves above at 8.2{V} but some of the motors run 4 cells on the oval?
Attached Thumbnails Click image for larger version

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