Thanks. I'll post some more detailed photos when it's completed. :)

Jhautz, yea it has me worried too. I purchased my pinions on the specification from the seller of a 7mm face width, but they turned out to be 5mm wide when I got them. I'm going to try it anyway and see what happens. The spur gear is actually deformed so I'm going to be getting more made anyway - the guys who made this one refunded me for their bad work luckily. It feels like Nylon despite me requesting Delrin, so I suspect it won't last!

That is a very nice heat sink layout. I should try that on my Jazz 55s.

Do you find you need it, lutach?

From my perspective i don't think you will need this complex heatsink design, because you won't push the Jazz to the same powerlevels (up to 4KW) as he does with his big heli.

I found this graph of a heli guy using a jazz 55 with a Neu 1910/1Y using 8s lipos. Power levels up to 2.3KW and an average amp draw of 42A. On your car i would expect your highest bursts between 1.2-2.5KW but your average amp draw will not be even close to 42A. I think it would be more in the range of 8-15A.

The only thing i did is mount the ESC upside down and removed the heatshrink where the cooling plate is (this improves heat dissipation). After a hard continouus run the cooling plate feels only warm to the touch (This is with power levels up to 1.7KW and 10s1p A123 in a 9lb 1:8 buggy geared to 67km/h (42mph)).

Very clean layout ... looking forward to read about your maiden run.

I have one with a small heat sink and it does help. The one I used with the Align didn't overheat, but it stopped working. I will probably make heat sinks for all my Kontroniks.

It will be interesting to see how mine works out. I will be running 10S so my current draw should stay below 40A. I wish I had purchased a 1907 instead of this 1912. I'm 90% certain 1912 will be way overkill, and a 1907 is 100g lighter (and cheaper of course).

My biggest concern so far is my gearing setup and the fact that these Neu 1900s cog quite heavily. The cogging might be a bad thing for coasting and I suspect might cause startup issues.

Hi

I started experimenting with replacing steel fastners with aluminium ones. It looks like I won't save 100g as hoped, but 40-50g I will. Not sure it's worth it TBH. Alu screws aren't cheap, and I'm only able to get them in one length so there's a lot of manual resizing that I have to do.

Well I got half way with it today before running out of alu screws. I might as well finish it though so will buy more next week and replace the second half. Photos below show today's weight saving.

Small update in my blog.

Hi

My X1-CR is finally running! I don't have a painted canopy yet, and still a couple details to sort out, but I gave it a maiden run this afternoon and am rather impressed.

Video here (XviD encoded, 42MB)

Gearing is a bit noisey and Jazz 55-10-32 throttle takes a bit of getting used to, but so far it's been good. I'll have more data to post in a couple weeks when I get my DPR back from a friend.

Enjoy. :)

I was looking at the Kontronik controllers but I don't know anyone using them. What driving adjustments did you have to make in regards to throttle?

I have used almost all the kontronik line of ESC. They are great. Pricey, but great.

@aragon
Great to see that you finally maidened her. She definitively seemed to be too fast for your driving spot ;-) More than enough starting and braking power with this setup and no cogging at all. I'm looking forward to see some DPR data.

@starscream
I do use those Kontronik ESC too since they are very popular in Europe but normally you will find them in helicopter applications. But they do have 2 car programs with proportional braking and reverse and served me well in a 1:8 buggy and now in a 1:8 truggy conversion. They certainly are underrated as my Jazz 55-10-32 is listed with a max short burst of 65A and i have some eagletree graphs with up to 95A peaks and 2275 watts.

run 1 on a big open tarmac place: eagletree graph

run 2 on grass: Eagletree graph

When you use it at this power levels a small heatsink could be needed during summer time (in my lighter buggy i never used one during summer but the power level was somewhat lower max 1.7Kw). As for now i never had thermalling with a complete shut down.

I made some video clips of my maiden with the truggy and the Jazz55 in this thread. And you can see the jazz 55 in action in my buggy when you look at the videos i'm linking to in my signature.

starscream, I find the car doesn't coast freely when the throttle is released suddenly. Looks like it brakes for a split second and then lets go again. I'm guessing it is specific to my motor and this firmware as I have a Jazz 40-6-18 and Hacker C40 in another car and it runs great.

I'm going to be putting a Crowdpleazer body on this car, so it will eventually be run without much ventilation (no fuel cap and engine openings). With the stock body installed the ESC gets slightly warm - maybe 35 celcius? The motor gets hotter, but cold enough to keep two fingers on it - I would guess about 50 celcius. Will try take more accurate measurements soon.

There are still other things I still need to do. Most important is sealing the motor. I'd like to run it on the track sometime against some nitros. :)

These Jazz ESCs are actually well priced IMHO. If you look at what the alternatives cost (MGM, Schulze, etc.), they're dirt cheap. I wish they were more popular in cars - that might give Kontronik reason to extend their car firmware support. Personally I'd like some improvements made to the forward/reverse program.

It seems that the more voltage you add the more power the braking has. Try and set your EPA to see if that helps. The first video I made you can actually see how strong the brake is: http://www.youtube.com/watch?v=-yrzb2EYsug. I adjusted my EPA and it was working really good.

Oh, I've got plenty of braking power! Don't need more. :D

The Jazz's onboard LED lights up when throttle is at neutral, full open, and full brake.

Looks like your truck has plenty braking too. ;)

Othello, your buggy looks awesome. I remember seeing that vid the other day. Your setup looks very well balanced too. I think mine might have a bit too much forward weight as it tends to understeer.

>I find the car doesn't coast freely when the throttle is released suddenly. Looks like it brakes for a split second and then lets go again

well ... you are not the only one experiencing this phenomenon. 95% of my driving is on a rather loose and dusty surface where i didn't noticed it. But when i drove my buggy on tarmac i noticed it too. Not every time when i released the throttle but from time to time. This also comes in to play when you are jumping since this short braking phenomenon will let your nose dive as you release the throttle. I even made a small video where you can see this split second brake (my comments are in german though): video clip. Look close at the front suspension.

gas loslassen = release throttle
bremsen = braking

Thanks for sharing. Glad I'm not alone!

Maybe we should both take this up with Kontronik? Would be nice to get a fix from them. :) I would guess it's just a firmware issue...

What firmware version are you running btw? 8 over here...

It might just be the torque the magnets make. I might be wrong.

Hey!

I finally ran my car with the DPR. Results are in my blog.

I was also experimenting with the Jazz throttle/brake control. Here is my understanding of how it works, based on how it responds.

When the trigger is moved anywhere above center, the Jazz tries to speed the motor to that level immediately. It does that for both positive AND negative acceleration, meaning that if you're running at 70% throttle, and you slow to 30%, the Jazz will apply brakes to get the car to 30% quickly. If you're on 70% throttle and you quickly release to 0%, it will brake very quickly as the trigger decreases, but once 0 is reached it lets the wheels run free. If you speed up again to 30% while it is coasting above 30%, it will brake to get you to 30% before applying power to maintain 30%.

Well this is very weird behaviour, but I guess one could get used to it. I'm going to pop a mail to Kontronik to question them about it and see if there's any way to disable that "feature" without a firmware upgrade.

Othello, would be cool if you could confirm the same behaviour and also mail Kontronik. :)

Oh, I might need cooling when I get my closed crowdpleazer body. Motor temps hitting 140 with the stock nitro body installed (the one with the big precut engine/tank holes). Or maybe it'll stay cooler on dirt. I get enough traction on tar to pull a wheelie atm. :)

I'm running Maxamps 2100 packs btw. They appear to be coping with 30C discharge rates! They dump alot of voltage under those loads, but they're not puffing. Time will tell how they last... :)

>Maybe we should both take this up with Kontronik? Would be nice to get a fix from them. :) I would guess it's just a firmware issue...

A german guy did exactly this and had some talk with kontronik. But he was only told to use the "car" specific controllers and that he was the only one experiencing this behaviour (he used a Jazz 80-6-18). Seems to me they will not be too cooperative about this. But when more and more people will complain they might change their firmware. But you mainly see those ESC in air/heli application.

I too saw regenerative braking in my logs: graph. The eagletree micropower does not get confused by the current flowing to the battery when braking. Weird that the DPR resets it's zero point to 26A. Average Watt and amperes are hard to tell this way. 1077 watts average would dump your battery rather quickly ;-))

I can absolutely confirm your findings but obviously got used to this behaviour (i drive Jazz ESCs in 1:8 conversions since half a year) especially as i mainly drive on loose surfaces with quick throttle position changes where it does not get so obvious as if you would drive on a high grip surface with gentler throttle impulses. It sure would be better if the ESC would not kind of brake to get from 70% throttle to 30%. It is worth a try to shoot kontronik a mail about this but i do not think there is an easy way to change this behaviour by ourselves. It sure implies a firmware change.

The more traction, the higher your Amp Peaks will be and your ESC and motor will heat up accordingly. My findings were that even if you see almost the same average Amps on different tracks, temperature levels of the ESC and motor are quite different when you drive on loose or on hard packed tracks. On grass i pulled up to 2,27KW (95A with 10s A123). So the jazz is up to the task and is able to provide more than 65A but will heat up easely when used constantly up to this power levels. No thermal shut down as of yet but I might need a small heat sink especially when ambient temps will rise here during summer. I never needed one when i used the jazz 55 in my lighter buggy with power levels up to 1.7KW, but the truggy needs more power (obviously) and thus heats up the ESC quicker.

140F is more than i expected from this big motor, but it is not critical at all. What was your outside temp when you drove?

EDIT: can't see the firmware version, as i mounted my Jazz with the cooling plate facing upwards.

For a Jazz 80-6-18, I guess their car specific ESCs are an option. They don't have any HV ones though. :) Another idea I have is to try forward/reverse mode to see if the throttle responds the same as forward only. Will let ya know.

After thinking about it for a while, for dirt track racing the brake-to-speed behaviour might be advantageous. Kontronik must have had a reason to program it like that - maybe they know something we don't. :)

Temperature started at 80F, which is 26C which sounds right for today's ambient temperature. Summer here. :) I think these motors max out at 200F (magnet limit) so there is some headroom. I'll see how things go when I get my closed body and take it on the track. If it's still bad I might attach a heatsink that protrudes through the top of the body.

I think your Jazz will be version 8 too. I don't recall this behaviour from my version 7 Jazzes. Heck, if version 7 doesn't do this, we could ask Kontronik to downgrade our Jazzes. :) Only improvement I noticed in version 8 was that forward/reverse mode was made usable.

You should see the same behaviour with forward/reverse mode as i'm using this mode with my jazz 55.

>After thinking about it for a while, for dirt track racing the brake-to-speed behaviour might be advantageous. Kontronik must have had a reason to program it like that - maybe they know something we don't.

True. I drove my truggy today on grass and never felt that it braked too heavely when i reduced throttle. It's only on tarmac where this behaviour can start to annoy me. I think it really depends how the car is geared, how much the car wheighs and the resistance of the motor when turned without actually applying current. The braking behaviour actually was more obvious in my lighter buggy than now in my truggy.

140F max with 80F ambient temp is nothing to get too worried about.

Interesting that your jazz v7 did not show the same behaviour. Seems to me it's only firmware related then. A downgrade should be possible, but to be honest it doesn't bother me this much ... A firmware up/downgrade would certainly take a good week at least (Austria is a neighbouring country to germany).

You're lucky to live so close. If the problem ever bugs you enough you could pop them a visit and take your car with. :D

Will let you know if I mail them about it. Probably only in the new year as I think they're closed for the holidays atm...

Thanks for sharing. :)

Hi,

I finally got the opportunity to drag race my X1-CR. Against nitros too! The venue was Boyz Toyz, a local RC car shop here, where a 40 meter straight track was setup (1:10 equivalent of a quarter mile).

I WHIPPED ASS.

Best time of the day by moi - 3.24 seconds
Best nitro time of the day - 3.62 seconds

And I have some evidence too!

Video High Quality (h.264 MP4, 20 MB)
Video Low Quality (XviD AVI, 20 MB)

All my heats are at the end. I'm the dude in the safari hat!

Those nitros were slow. Man your buggy is nice. Great job on the nitro :whip:.

Hi all,

I finally got around to sealing my motor. I made a front cap up of fibreglass which turned out really well. Fits like a glove and only 3 grams. Should hold up to heat too.

Taking a short cut for the motor's rear - just some aluminium tape. Not sure how the contact adhesive will hold up.

I'm hoping to take some nitros on on the track. :)

Very cool. Are you planning to make a video?

If I can find a camera man, definitely. :)

Cool. I'll be watching.