Kontronik Jazz testing

Hi all,

I did my first tests today with a Kontronik Jazz controller in a car. Only one weird thing happened so I'm fairly upbeat about running a Jazz on my 1:8 conversion. The motor and ESC barely felt warm after full throttle runs up and down a slightly inclined road. And this is with zero cooling and minimal airflow around the ESC.

When I get my new rear wheels setup I will do some tests on grass. And maybe some tests at 6S. I only have one pinion, and on 6S the car will be mathematically capable of 80 MPH!!! 40 MPH is scarey enough, so I think I need to first get new gearing...

I will get some video of the car soon, but for now text, photos, and test data will have to do. Instead of repeating myself with lower resolution graphics, check out my blog. :)

More feedback to come!

[jnev]

Cool!!! If the old works, why change it?:)

Can't wait fort he video. :027:

I'm stoked at getting my RC10 going again. I'm going to be retrofitting B4 rear shafts so that I can run modern prolines at the back, and I'll be replacing all the ball links to try get everything working slop free. My steering accuracy is sooo dodgey right now. :)

I've heard Associated have changed all the plastic parts to black, and some parts aren't available anymore. I still plan to get a new 1:10 car that I can drive more often and maybe race too...

I'm going to take my RC10 to an indoor cycling speedway tomorrow night. I usually fly my helis there, but the track would be AWESOME for getting a car upto speed too! I should have plenty of potential cameramen available. :)

Hi. I put my RC10 on the Speedway last night. Talk about fun! Not often you get to run a car at non stop full throttle! :D

I was aching for more speed. On the speedway it feels WAY too slow... like a golfcart. I think I can easily double its speed for this track. Next week I'm going to take my 6S setup with me.

I got some video of it all. I also included some low speed driving so that the Jazz startup can be seen. I'll post a better, more agressive low speed video sometime as the flat section of the speedway was just too slippery.

Enjoy!

Video (11 MB, XviD encoded)

[captain harlock]

After the speedrun, you think your Jazz can be used in a heavy truck with a cooling fan and a heatsink?

I think it all comes down to how much power your setup needs. My RC10 weighs 1.5 kg RTR and pulls about 300 Watts peak with current gearing. At 11.1V, 300 Watts is well within the limits of the Jazz 40-6-18. It barely gets warm right now.

Next week when I run 6S I will do the runs with my DPR attached to record power levels. I will be using larger rear wheels and smaller gearing, but in total the top speed will still be about double, so power should shoot up to 700 Watts or more. On 6S that is still well within the limits of this Jazz so it should be fine, but we will see what happens. TBH I am more worried about my little RC10 gearbox handling the speed.

In theory the Jazz 40-6-18 should be good for over 800 Watts continuous.

Let us know if you ever try this out in an 1/8th scale. I'm curious to know how it would work out, given the controller published current limitations.

One thing with the Jazzes is that they're not easy to cool. You can put a fan on them, but adding a heatsink is a big, warranty-voiding operation. AA, will do. :)

[BrianG]

Wow, I really like that speedway! It would be a blast I think to be able to run top speed in something other than a straight line. Looks like your car runs well too!

[Procharged5.0]

Originally Posted by Aragon

One thing with the Jazzes is that they're not easy to cool. You can put a fan on them, but adding a heatsink is a big, warranty-voiding operation. AA, will do. :)

Cooling was the first thing I thought of when I saw the esc.

It's tough to dissapate heat when it's inside a plastic case!

[nativepaul]

The power required for a speed is not linier but goes up with a square so if you can do 40mph with 300W, 700Wwont give you 80mph it will give you just over 60mph, to do 80mph you would need 1200W

Thanks Paul! I did realise it was not linear, but had no idea how non linear it is. I'm currently geared for about 35 mph so double would be 70 mph. I guess it'll take closer to 800W to hold full speed? If so, this should be a good test indeed!

BG, my steering and camber links have a lot of slop. Other than that it is running pretty well. :)

[zeropointbug]

It's actually more than the square of the speed increase. The wind drag is the square.

You have to take into account:

-wind drag
-tire resistance
-drive train resistance

So, for example going from 40mph to 80mph, the motor needs twice the torque, AND twice the speed to overcome the wind drag. Also, the whole drivetrain resistance goes up linearly, so the wind drag, which goes up as a curve with speed, and resistance, which goes up as a straight line. Add them together and it's more than the square of the speed increase. It becomes less apparent the faster you go.

Likewise, at low speeds, tire and drivetrain resistance is the major player at those speeds. Wind resistance is minimal, as it goes down drastically as you lower speed.

Is there anything practical that I can do to minimise drivetrain drag? Last night I could swear my gearbox felt warm after a few laps at full tap...

[zeropointbug]

there are losses in the transmissions... but being warm is nothing to be worried about. Do you have lube or grease on the gears? I don't think there would be anything you can do minimize drive train resistance, unless you designed one yourself that was very efficient, but you won't gain much. I was just pointing out a statement that the power requirements are more than the square of the speed... more of the drag are at the tires to be honest, and you can only have so little drag their before it's not a tire anymore. (that's what a tire is... right? :027: :eek: )

You COULD attach CD's to your car and that would give more speed? :005: