RCCrawler Forums

Krylar · 02-10-2009, 03:59 AM

Intro: I'm building an RC tank from scratch. This isn't *exactly* a rock crawler, but I'm going for the same type of speed and power here and hence looking at the same ESCs/motors. The tracks will be soft for gripping rocks - picture a fan belt made out of rubberband material.

Vehicle size: Typical 2.2 size. About a 12-inch 'wheelbase' (measure the tracks front to back).

Target speed: 3-4mph (typical crawler speed)

My drive pulley will need to turn at approx. 2000RPM's to drive the tank at the target speed, given the pulley to belt length ratio. I'll need two motors, one for each track, and therefore two ESCs or an ESC that handles two motors.

I'm looking at the Warrior-R by JP Custom RC's which (from what I gathered from some posts on here) I can expect to get about 4500RPMs from at 4.8V (4x 2/3A cells). With a 2:1 gear reduction, that puts me just over the target RPM. I'm concerned here, however, that I may be going overkill here by running two of these, and maybe I should step down to a smaller motor?

Also, can someone recommend a two-motor ESC, or an ESC that I could run a pair of easily? Note that I'll still need a servo (or two!) .. I have other uses on a tank for that :-D

Thank you for your input.

rex21 · 02-10-2009, 05:53 AM

You are going to need 2 esc's, so you can control each track independantly.

hairba11 · 02-10-2009, 08:00 AM

also trying to drag the weight of the tank around, and overcome the tension of the tracks, I would go for a higher speed motor with more gear reduction. sounds like an interesting project so please keep us updated

constantmotion · 02-10-2009, 10:42 AM

E-Maxx ESC would work fine....

Greatscott · 02-10-2009, 11:41 AM

An EVX will run two motors. Assuming one motor per track, what is your plan to control them seperately, so you can turn, or are you just going to point the tank in one direction and let her rip?

How much of this are you going to fabricate yourself and how much are you going to use existing parts (like from a Tamiya tank)?

engineerjoe · 02-10-2009, 05:35 PM

You might be able to make a potentiometer dig that would be servo driven for steering, or make a berg dig mechanism (this would stop the tracks completely tho)

Greatscott · 02-11-2009, 10:04 AM

The easiest way would be to operate it with two ESCs, but another way to do it would be to wire up the EVX through two machanical speed controllers (MSC), you'd just need a common servo with linkage to both MSCs (this would be the budget build). The trick of this would be to have the linkage setup so that the MSCs started out in the first forward slot of the MSC (using a 3-speed MSC). This way you could control it with a pistol grip 2 channel radio, you'd have to work something else out for control of the turret.

02-10-2009, 03:59 AM	#1
Krylar Newbie Join Date: Mar 2007 Location: Sanger Posts: 6	Buildilng RC Tank - Review my parts Intro: I'm building an RC tank from scratch. This isn't exactly a rock crawler, but I'm going for the same type of speed and power here and hence looking at the same ESCs/motors. The tracks will be soft for gripping rocks - picture a fan belt made out of rubberband material. Vehicle size: Typical 2.2 size. About a 12-inch 'wheelbase' (measure the tracks front to back). Target speed: 3-4mph (typical crawler speed) My drive pulley will need to turn at approx. 2000RPM's to drive the tank at the target speed, given the pulley to belt length ratio. I'll need two motors, one for each track, and therefore two ESCs or an ESC that handles two motors. I'm looking at the Warrior-R by JP Custom RC's which (from what I gathered from some posts on here) I can expect to get about 4500RPMs from at 4.8V (4x 2/3A cells). With a 2:1 gear reduction, that puts me just over the target RPM. I'm concerned here, however, that I may be going overkill here by running two of these, and maybe I should step down to a smaller motor? Also, can someone recommend a two-motor ESC, or an ESC that I could run a pair of easily? Note that I'll still need a servo (or two!) .. I have other uses on a tank for that :-D Thank you for your input.

02-10-2009, 05:53 AM	#2
rex21 Pebble Pounder Join Date: Oct 2007 Location: Star Prairie, WI Posts: 165	You are going to need 2 esc's, so you can control each track independantly.

02-10-2009, 08:00 AM	#3
hairba11 RCC Addict Join Date: Mar 2007 Location: St. Louis (High Ridge) Posts: 1,279	also trying to drag the weight of the tank around, and overcome the tension of the tracks, I would go for a higher speed motor with more gear reduction. sounds like an interesting project so please keep us updated

02-10-2009, 10:42 AM	#4
constantmotion On the lookout for Rocks Join Date: Mar 2006 Location: Monroe, Louisiana Posts: 3,711	E-Maxx ESC would work fine....

02-10-2009, 11:41 AM	#5
Greatscott I wanna be Dave Join Date: Jul 2005 Location: North Idaho Posts: 3,648	An EVX will run two motors. Assuming one motor per track, what is your plan to control them seperately, so you can turn, or are you just going to point the tank in one direction and let her rip? How much of this are you going to fabricate yourself and how much are you going to use existing parts (like from a Tamiya tank)?

02-10-2009, 05:35 PM	#6
engineerjoe Rock Crawler Join Date: Jan 2006 Location: SUPERMOTO heaven Posts: 695	You might be able to make a potentiometer dig that would be servo driven for steering, or make a berg dig mechanism (this would stop the tracks completely tho)

02-11-2009, 10:04 AM	#7
Greatscott I wanna be Dave Join Date: Jul 2005 Location: North Idaho Posts: 3,648	The easiest way would be to operate it with two ESCs, but another way to do it would be to wire up the EVX through two machanical speed controllers (MSC), you'd just need a common servo with linkage to both MSCs (this would be the budget build). The trick of this would be to have the linkage setup so that the MSCs started out in the first forward slot of the MSC (using a 3-speed MSC). This way you could control it with a pistol grip 2 channel radio, you'd have to work something else out for control of the turret.

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