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Old 12-20-2007, 08:25 AM   #1
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Talking Excel top speed calculator

i made this because i was bored, and because i wanted to know my top speed not my rollout. i think i got it right, so if theres anything wrong tell me.

btw its defaulted to an 'out of the box' HPI E10. and as it says, only edit the yellow cells or you'll break it

if you have no internal gear ratio, then set it to 1.

Joe

p.s i added an extra unit of speed for all you speed freaks!
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File Type: zip speed calculator 1.21.zip (5.2 KB, 434 views)
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Last edited by joe of loath; 12-20-2007 at 03:28 PM.
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Old 12-20-2007, 09:30 AM   #2
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from what I saw, theres no Pi in your formulas anywhere, and your overall gear ratio needs to be spur/pinion * internal gear ratio.

you can fudge aerodynamic drag by multiplying by .95 or .8 or pick a number less than 1, or you could figure out/find the formula for drag

good luck
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Old 12-20-2007, 01:01 PM   #3
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hmm strange, it seems to work..... i know, i should replace diameter with circumfrence.
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Old 12-20-2007, 01:06 PM   #4
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Quote:
Originally Posted by gacjr0 View Post
from what I saw, theres no Pi in your formulas anywhere, and your overall gear ratio needs to be spur/pinion * internal gear ratio.

you can fudge aerodynamic drag by multiplying by .95 or .8 or pick a number less than 1, or you could figure out/find the formula for drag

good luck
i'm still not sure how to work out inernal gear ratio. i did it as 7.48 (final ratio) minus 4.25 (spur/pinion)... total bodge job!

oh and aerodynamic drag is exponential (or is it squared or cubed) anyway it isnt linear....


EDIT: a bit of trial and error later i seem to have my internal gear ratio sorted, but still no formula... it works as logn as you know it!

EDIT: it wont work.. somethings wrong :'(

EDIT: ok i got it working! there were some relics in the equations from when i was working in millimeters.
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Last edited by joe of loath; 12-20-2007 at 01:59 PM.
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Old 12-20-2007, 02:12 PM   #5
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ok it seems to work now.

btw this is just a bump TTT
^
|
|
|

EDIT: now changed tyre diameter into MM from meters
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Last edited by joe of loath; 12-21-2007 at 03:17 PM.
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Old 05-19-2008, 11:34 AM   #6
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bump, just in case someone actually cares.


p.s. IT WORKS!
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Old 05-19-2008, 02:46 PM   #7
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anybody got an idea of the RPM of a 4.5R brushless motor?
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Old 05-19-2008, 10:53 PM   #8
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When trying to open the file, it says the file is corrupted.
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Old 05-20-2008, 04:38 AM   #9
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Quote:
Originally Posted by shadow102 View Post
anybody got an idea of the RPM of a 4.5R brushless motor?
Kv * volts

so for a 6600kv motor it's 6600*7.2(or 7.4 if running lipo)
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