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-   -   Excel top speed calculator (https://www.rctech.net/forum/electric-road/196558-excel-top-speed-calculator.html)

joe of loath 12-20-2007 07:25 AM

Excel top speed calculator
 
1 Attachment(s)
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!

gacjr0 12-20-2007 08:30 AM

from what I saw, theres no Pi in your formulas anywhere, and your overall gear ratio needs to be spur/pinion * internal gear ratio. :cool:

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

joe of loath 12-20-2007 12:01 PM

hmm strange, it seems to work..... i know, i should replace diameter with circumfrence.

joe of loath 12-20-2007 12:06 PM


Originally Posted by gacjr0 (Post 3991462)
from what I saw, theres no Pi in your formulas anywhere, and your overall gear ratio needs to be spur/pinion * internal gear ratio. :cool:

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.

joe of loath 12-20-2007 01:12 PM

ok it seems to work now.

btw this is just a bump :D TTT
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EDIT: now changed tyre diameter into MM from meters

joe of loath 05-19-2008 10:34 AM

bump, just in case someone actually cares.


p.s. IT WORKS!

shadow102 05-19-2008 01:46 PM

anybody got an idea of the RPM of a 4.5R brushless motor?

SpidarX 05-19-2008 09:53 PM

When trying to open the file, it says the file is corrupted. :confused:

joe of loath 05-20-2008 03:38 AM


Originally Posted by shadow102 (Post 4459029)
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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