RC Tank Warfare community hobby forum

I'm planning on building a 1:8 scale tank from scratch.
Approximately what sort of rpm for the drive sprocket should I be aiming for?
Thanks.
Also,
BT series tanks don't actually have a toothed drive sprocket. What's the correct term. A drive wheel?

The BT 7 had a top speed off road of 50 Kph so that divided by 16 gives you a scale max marker of 3.125kph
If you count the rotations of your drive wheel (mark it with a suitable visual line like white paint pen) over 15 seconds then multiply that by 4 to get the rpm in real time/per minute, then calculate that into the 3.125 kph you can adjust your gear ratio as required.
I reckon a bloke that can use a dividing head to great effect can easily work the maths on that
You may need to use an idler gear to slow down or speed up , really depends on what your gearbox is at the moment

MikeN wrote: ↑Sat Apr 27, 2024 10:53 pm BT series tanks don't actually have a toothed drive sprocket. What's the correct term. A drive wheel?

Dead on!
Drive wheel is the best general term as there are some vehicles out there that have both a toothed drive wheel and a toothed idler wheel, Churchill for example.

Ok thanks,
I didn't know that about working out scale speed.
So. To achieve an actual speed of 3.125 kph ,
I will have a drive wheel 80mm diameter, that will be laying down track at a rate of 0.251 mtr per revolution
So to cover 3.125 km it needs to revolve 12450 times (in one hour).
Divide by 60 mins gives 207.5 rpm.
I think.

If your math's is right , and Im sure it is, thats for the maximum top speed off road .
Depending on your gearbox set up, you may need to allow a different ratio so you get the best drivability at realistic control levels with the overall weight of your creation taken into account.
You can always drive it slower if required!!............

"ome vehicles...have both a toothed drive wheel and a toothed idler wheel, Churchill for example." Why the toothed idler? Does it help keep tracks on more securely?