Steve: This is my first tank,so I am not an expert. For goning in a straight line it should not take a big motor, but a "pivot-in-place" type turn is another situation. A "Pivot-in-place" turn is going to take a LOT of torque.
My setup will produce about 80 pounds of force at the track (without overloading the motor too much). My tank will weigh about 150 pounds. Hopefully, 80 pounds will be enough to "pivot-in-place". The force you get on the track is the inch pounds torque of the motor times the final drive ratio and divided by the radus (in inches) of the track drive sprocket. My tank: track drive sprocket = 1.5 inch radius full load motor torque = 84 inch pounds Final drive ratio = 1 force on the track = 84 inch pounds X 1 divided by 1.5 = 56 pounds If I overload the motor by 40% then I end up with about 80 pounds force on the track. I am hoping that will be enough to skid turn (pivot-in-place). A 175 pound tank will be harder to skid turn than a 150 pound tank. A lighter tank will turn easier. The way I fiuure it, my 150 pound tank has 75 pounds sitting on each track. With 75 pounds on the track, can 80 pounds force on the track make it skid? If I change the final drive gear ratio to 2 to 1 then I could get 2 X 80 pounds = 160 pounds force on the track. The trade off is it also cuts the top speed in half. Anyway, all of this is just mathamatical guess (bull s---t). I have my fingers crossed that these motors (and the final drive ratio & track sprocket size) will work OK. The other guys here could answer your question better than me. Mark On Feb 17, 4:32 pm, steveh <[email protected]> wrote: > Mark, thanks for the response. Since I am not sure about the torque, > let me see if you can answer my question. The unit I am building > Is projected to weigh in at around 175lbs. I only need to be > able to achieve a speed a little faster then walking. Do you > think that motor would be sufficient? > Thanks > Steve > > On Feb 17, 5:11 pm, Mark_123521 <[email protected]> wrote: > > > > > Steve: > > > Those are electric bicicle motors, 450 watts, 24 volts. > > >http://www.electricscooterparts.com/motors.html#top > > > They have a 7 or 8 to 1 gearing built in. > > 550 RPM and 4.5 inch pounds of torque per amp. > > > Mark > > > On Feb 17, 12:11 pm, steveh <[email protected]> wrote: > > > > Mark, what kind of motors are those in the pictures? > > > Thank You > > > > On Feb 11, 10:08 pm, Mark_123521 <[email protected]> wrote: > > > > > Check out the progress. > > > > I have just completed a bar with my suspension and road wheels. > > > > The suspension has a travel of 1.25 inches. > > > > Each wheel has an initial force of 10 pounds and a fully retracted > > > > force of 14 pounds. > > > > See how the road wheels engage the track guide tabs. > > > > >http://i192.photobucket.com/albums/z65/mm123521/HPIM0726.jpg > > > > >http://i192.photobucket.com/albums/z65/mm123521/HPIM0725.jpg > > > > >http://i192.photobucket.com/albums/z65/mm123521/HPIM0724.jpghttp://i1... > > > > > Mark- Hide quoted text - > > > > - Show quoted text -- Hide quoted text - > > > - Show quoted text -- 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
