Mardave VRX CE 21.5 2s rollout
 

Evening all

What's the recommended starting mmpr for a 21.5 on 2s (medium size carpet track)?

I run 60-65mmpr with my 13.5 1s on the same track depending on layout.

Hi,
When I did my testing a year or so ago I would usually end up 2 pinions lower on my 2s/21t setup than I did with 1s/13.5t.

This was for small-medium sized tracks (biggest regular track I attended was 20x12m and the smallest was 17.5x10m).

NOTE: This was with a fixed timing HobbyWing 21.5t motor. My guess is that "modern", variable timing 21.5t motors will still need to be geared lower than a 13.5t but it might be just one pinion.

Hope this helps,

James

This is the motor:

http://www.hobbywing.com/product_show.asp?id=305

Using a Speed Passion Reventon R esc in blinky

Ok, not exactly the same as the ones I used, but by the looks of it yours is non-adjustable with the timing? Probably just a change in paint from what I used...?

From this, I would suggest a gearing of between 55mm/rev and 60mm/rev, depending on track size.

By the way, what cells are you using? In my testing I started with "shorty" packs. These were extremely fast to recharge, even at 1c charge rate their capacity of 4200mAh meant that a charge rate of 4.2A recharged them in less that 15min (2s/21.5t takes very little capacity out of the cells). However, the shorty packs are slightly bigger than hard cased 1s packs, expensive and heavy. I ended up with the 1800mAh packs used in micro off-road buggies. These were cheaper, still recharged quite fast but I had to be a bit creative when fitting them to my chassis and getting it back up to 950g weight.

If you search for "How to power a Mardave" and read the thread on RCRaceChat, all my test data is there

James