Ok well here is my math so far. I did this with a 14.4v drill battery (fully charged) and a stop watch. I got 80 RPM
I determined that with two drill batteries I would get about 160 rpm. So then I solved for X if 28.8v = 160 then 24v = 133.3 I used the calculator you posted up to determine my top speed. Since these motors have a ratio of 24:1 I will gear this motor to 12:1 by putting a 40T sprocket on the motor's output shaft and a 20T sprocket on the drive shaft. So it comes down to RPM being 130, Gear ratio I set to 0.5:1, wheel diameter is 9" this gives me 11.2kph or 7mph. I think this is just under the scale speed of a king tiger Now do you think the motors would hate me if I was to over volt them to 28.8V for continuous use? I was thinking of just using my two cordless drill batteries. This way I could achieve a top speed of 15.3kph or 9.5mph On Mar 2, 9:34 pm, George Mastoras <[email protected]> wrote: > Heres another speed formula that seems to give you half the speed of the > other, don't know how accurate this is but it should be better, need to add > losses to the total. > > http://www.4qd.co.uk/faq/roadspd.html > > On 3/3/09 4:21 PM, "Modena" <[email protected]> wrote: > > > > > same as for a car, take the circumference and the RPM of the drive > > wheel and you can work out the rest. > > > Note: do not forget to add on the thickness of the track (chain if > > you're using it) and the track pads, it is this ("overall") > > circumference that you need, and its easiest to get this by obtaining > > it from the diameter of the drive wheel with the track wrapped around > > it, then calculate circumference from diameter with pi > > > Once you have an accurate circumference and the RPM, you can work out > > MPH, or work out RPM if you know what MPH you are looking for. > > > Ben > > > On Mar 3, 4:19 pm, "Chrysanthos Kanellopoulos" <[email protected]> > > wrote: > >> Joe's rule of four gets you to : > > >> 400 RPM * 4 " diam. * 3.14 * 60 = 301.440 inches per hour or 4.75 MpH > >> With a loss on the motors , this should get you to about 4 miles per hour. > > >> 400 RPM * 5 " diam. with the tracks on * 3.14 * 60 = 376.800 inches per > >> hour > >> : 63.360 = 5.94 MpH > > >> Chrys > > >> ----- Original Message ----- > >> From: "Chrysanthos Kanellopoulos" <[email protected]> > >> To: <[email protected]> > >> Sent: Tuesday, March 03, 2009 7:05 AM > >> Subject: [TANKS] Re: 3 stage transmission > > >>> Try: > >>> RPM * diameter in meters of drive wheel with the added thickness of the > >>> track on * 3.14 * 60 min. = speed as meters per hour. > > >>> YOu practically unfold the circumference of the drive wheel that many RPM > >>> times for an hour and get the distance. > > >>> If teh diameter is 113 mms., this dimension in meters is 0.113. > >>> There 's some loss with teh motors loaded but that depends on the gears > >>> It applies for wheeled vehicles too. > >>> Chrys. > > >>> __________ NOD32 3434 (20080911) Information __________ > > >>> This message was checked by NOD32 antivirus system. > >>>http://www.eset.com-Hide quoted text - > > >> - Show quoted text - > > --~--~---------~--~----~------------~-------~--~----~ You are currently subscribed to the "R/C Tank Combat" group. To post a message, send email to [email protected] To unsubscribe, send email to [email protected] Visit the group at http://groups.google.com/group/rctankcombat -~----------~----~----~----~------~----~------~--~---
