RC-Monster Forums - View Single Post - Excel worksheet for some of my speed runs

kulangflow · 06:39 PM

There must be something wrong with something.

I finally broke 51.3mph, but it took 12 cells geared at 27/84! The spreadsheet says that combo should take me to 77mph. Ummmmm ... nope. :)

The controller temp was 105F and motor was 150F. I tried 10 cells and 12 cells with 18, 20, 22, 25, and 27 Tooth pinions on an 84T spur.

I am baffled. This same controller (BK9918) with my 9L took my e-maxx to 45 mph geared at 22/66 on 14 cells, and that's dang close to what lipomax's spreadsheet says. Hmmmmm.... that tells me the controller and cells are fine.

Actually ... I am now thinking the problem is that these calculations are based on 32P gearing, while I'm using 48P gearing. The diameter of a 60T spur at 32P is way bigger than at 48P. How can I update these formulas for 48P gearing? Nope that doesn't make sense. Gear ratio is gear ratio regardless of pitch. Blast!

Thanks for reading my novel ... :-)

	(#13)
kulangflow Never Fast Enough Offline Posts: 914 Join Date: Jul 2005 Location: UT	09.29.2005, 06:19 PM There must be something wrong with something. I finally broke 51.3mph, but it took 12 cells geared at 27/84! The spreadsheet says that combo should take me to 77mph. Ummmmm ... nope. :) The controller temp was 105F and motor was 150F. I tried 10 cells and 12 cells with 18, 20, 22, 25, and 27 Tooth pinions on an 84T spur. I am baffled. This same controller (BK9918) with my 9L took my e-maxx to 45 mph geared at 22/66 on 14 cells, and that's dang close to what lipomax's spreadsheet says. Hmmmmm.... that tells me the controller and cells are fine. Actually ... I am now thinking the problem is that these calculations are based on 32P gearing, while I'm using 48P gearing. The diameter of a 60T spur at 32P is way bigger than at 48P. How can I update these formulas for 48P gearing? Nope that doesn't make sense. Gear ratio is gear ratio regardless of pitch. Blast! Thanks for reading my novel ... :-) He's down by the river ... walking on water. Last edited by kulangflow; 09.29.2005 at 06:39 PM.