The Limited Limitless

[Malice]

I achieved 81mph in a parking lot racing around islands. A bit on the fast side. Hit thermal on the motor (180*) at about 7 minutes in. 23/46 gearing. I'm not sure why but this car feels a bit intimidating. Ive gone significantly faster in my typhon...it just feels different i suppose.

 

[Malice]

Interesting..... I decided to swap from a 23 tooth pinion to a 20 tooth pinion before heading out today for my 3rd romp. For some reason I could not rotate the armature / rotor very smoothly at all. It would rotate about 3/4 of the way and then stop there. Pulled the 1717 1650 out of the car and placed it on the desk. Hooked up the esc / motor/ battery / receiver and applied slight power to the motor. It didn't sound right, it didn't feel right and was hotAF after about maybe 8 seconds. No issues with overheating thermal was set to 150* then bumped to 180*. I did reach thermal on the two times I took the motor out but that shouldn't be an issue. @jondilly1974 what happened when your kevlar let go? I haven't taken the motor apart. I probably won't.

I'm going to get in touch with @robert@castle or contact castle on monday to see about getting a RMA.

 

[jondilly1974]

Interesting..... I decided to swap from a 23 tooth pinion to a 20 tooth pinion before heading out today for my 3rd romp. For some reason I could not rotate the armature / rotor very smoothly at all. It would rotate about 3/4 of the way and then stop there. Pulled the 1717 1650 out of the car and placed it on the desk. Hooked up the esc / motor/ battery / receiver and applied slight power to the motor. It didn't sound right, it didn't feel right and was hotAF after about maybe 8 seconds. No issues with overheating thermal was set to 150* then bumped to 180*. I did reach thermal on the two times I took the motor out but that shouldn't be an issue. @jondilly1974 what happened when your kevlar let go? I haven't taken the motor apart. I probably won't.

I'm going to get in touch with @robert@castle or contact castle on monday to see about getting a RMA.

Open it up and take a look. Mine unwrapped and Castle replaced it. Took a month or so for the whole process, but they took care of me.

 

[Malice]

It appears we have twins. Immediately after removing the end cap I saw nothing but fibers!

 

[robert@castle]

It appears we have twins. Immediately after removing the end cap I saw nothing but fibers!View attachment 107242View attachment 107241View attachment 107243

Just replied to your PM but that absolutely appears to be the production fault we saw on the first batch of 1717. Contact support and they will replace the motor.

 

[Malice]

Just replied to your PM but that absolutely appears to be the production fault we saw on the first batch of 1717. Contact support and they will replace the motor.

Thank you!

 

[Malice]

While she is still a parking lot pounder I've decided to go another way. As some of you may know I'm currently working on my Typhon which is being converted from speed runner to GT. Im going to put the 1717 in there since it is sensored.

I've ordered a TP4060 1750KV for the Limited. Since this motor is longer, I had swap the motor mount around and lose a battery tray. Still wanting to run 8s, I needed to find a way to mount my batteries. I looked at some offerings online and came across one mounting solution, but as someone who owns a fully functioning machine shop, I couldn't justify spending 50 bucks on a flat piece of aluminum. I also didn't want to make one out of metal. Ever since I got hooked on 3d printing, I've wanted to print everything!
I came up with this design that uses 6 existing holes in the chassis. No need to drill and countersink new holes for a aftermarket tray. The base is 5.5mm thick. 70% gyroid infill. I made 3 total, and purposely broke two of them checking for weakness. All that is left is a little touch up work to remove evidence of a brim and then re-mount.

It is STRONG! You would have to intentionally try to break this. Fits perfectly, no body mods. Im happy. I need to figure out how I will mount this ESC and Cap pack, then wait for my new TP to show up and come up with a new fan mount.

 

[Malice]

TP 4060 1750KV showed up today. And it has rained for the last two days. Hoping to get it wired up and a fan mount made up shortly.


**Edit
Came up with this real quick. Test printing now in PLA at 70mm/s. Its' going to look like but if it fits as anticipated, I'll re-do it tomorrow in PETG.

 

[Malice]

Got everything zipped up and put together. This motor is rated for 29V according to the TP Power Website. Also 50k RPM. Took it out today with 27/46 gear ratio and truthfully, It seems on par with the 1650KV I took out of it. I definitely exceeded 50k rpm with no ill effects (I was in the lower 50's with the 1717, but it's also rated for 56krpm) It runs considerably hotter than the 1717 1650KV also. It is roughly 50 degrees outside. With two 40mm fans blowing I still hit 179-182* on the motor. ESC got up to 206* The hottest I've ever seen any of my now (6) MMX8S escs. I didn't temp my batteries but they were definitely warm. Trying to put enough strain on this motor to slow it down is going to be a challenge and require different gearing than I'm currently running and possibly a PPS motor mount for more range. I love the look of the mount and the range it offers...but I'm not a fan of the mesh adjuster. Alternatively, I guess I could run 6s but where is the fun in that?!?!?

Battery tray I fabbed / 3d printed works like a champ. Held both CNHL 4S packs firmly with no visible movement. I'm happy about that. Until I place another SAGA order for gears, I'm going to temporarily switch motors. A while ago I bought a Spektrum 1250kv motor from @phildogg (thanks again) so I'm going to swap that out real quick and go back out.

 

[Doom!]

I really like how clean this looks!

 

[LibertyMKiii]

Great work, I like that battery tray you made. I might have to do the same.
I have been holding off on flipping the motor mount, but it really opens up the chassis a lot once you do.

 

[SrC]

^^^ Some of the pulled data above looks erroneous.

 

[Malice]

^^^ Some of the pulled data above looks erroneous.

Feel free to elaborate. Your statement means nothing without additional information.

Great work, I like that battery tray you made. I might have to do the same.
I have been holding off on flipping the motor mount, but it really opens up the chassis a lot once you do.

Very much so. I resisted it also. The only reason I did it was because for a while I was down a motor, and I figured if I was going to order something else it might as well be black and gold. I really really wanted the TP4070 but in the event this motor ends up in another car, I wanted to have a small chance of it fitting. I was concerned about weight. I ran LTO pan cars back in the day and all the weight was on one side. Adjusting the suspension for that was kind of easy considering we drove around in a oval, on carpet, with no dips, debris or other stuff. I haven't noticed any handling issues. The collars for the shocks are about 2mm tighter(lower) on the left side. Handles like a champ! So much in fact that on the way home I was like, this would make an excellent speed car......NO! I can't! LOL.

 

[SrC]

I'm referring to Oct18 first Lim Run. ( MAX line) ?5,216? watts yet ripple is at .67. There was a decent sustained pull of 2 sec. I see. Is it me or it's under geared for 8S??? ?‍

 

[Malice]

I'm referring to Oct18 first Lim Run. ( MAX line) ?5,216? watts yet ripple is at .67. There was a decent sustained pull of 2 sec. I see. Is it me or it's under geared for 8S??? ?‍

It is very under geared. My goal with this car was to have brutal acceleration at the expense of top end and longevity. Here is another log using the same gearing, setup, batteries, etc...... with a Spektrum 1250kv.

 

[SrC]

^^^ now that's a big difference. That is much more efficient. Like Night and day...

 

[Malice]

I wouldn't call that efficient. I'd call it not up to par. Not quite trash, but not something that I'd run on a regular basis. The 1250 doesn't draw as much current as the other two motors. The only thing off about the Oct 18 graph is the rpm. If you look at the left I have a gear ratio entered other than 1:1. That does not provide the rpm of the rotor. My ripple current is always low. I have a typhon that will run in the 12* mph range and I hover around .4-.97 ripple with substantially higher current draws (some over 400). That 1250 appears to run cooler, definitely draws less current and has significantly less acceleration. On paper, there is about a 16k (58.8k vs 42k) rpm difference between the the two motors. That, in my mind, explains the differences in the readings you are referring to.

Here is a graph of my typhon at 116 mph. 383.8 amps with .4 ripple

 

[Malice]

Made a few changes and went back out today trying to get some lower rpm readings. I swapped to a 38 tooth spur gear and went up to a 29 tooth pinion. Nothing else was changed. I took her out on 6S and ran around normally like I do, and the temps were great as was the rpm and acceleration. The ESC hit about 150. I hit 94mph on the back straight away of the course where I usually only hit low 80's. That is more than sufficient for my purposes. It got there quickly and I had ample room to brake before turning. Would like it to be a little slower. I can not any further compare it to the 1717 1650kv because I only ever ran 23/46 with it. This motor I started out a 27/46 because of the difference in kv.

I hooked up 8S and this is where things changed.... Dramatically. On 8s, I'm looking to keep the rpm at a safer level, while still maintaining what I can only describe as instantaneous 0-90000000000000000000MPH acceleration. I was only interested in seeing how much lower I would be able to keep the RPM with this gearing. The temperature on the motor and esc were great....... about 13 degrees warmer on the motor. I decided to wind it out just to see peak rpm. I wasn't interested in the speed just the rpm, so I turned off my SKYRC gps. At sustained throttle, my car turned into a airplane, did a single back flip, landed on its wheels and kept going. When it touched down, the GPS mount broke (3d printed) and it threw the GPS from the car. I immediately laughed and said to myself, I wasn't using that thing anyway. No damage to the car ( I kept running). The rpm is still a little on the high side, so I may go to a 32 pinion and retest for rpm and temps. I'd like to hover around 45k +/- 500.

This motor is McNasty. No signs of being sluggish or over tasked. The sound the car makes accelerating makes me smile!

 

[LibertyMKiii]

Made a few changes and went back out today trying to get some lower rpm readings. I swapped to a 38 tooth spur gear and went up to a 29 tooth pinion. Nothing else was changed. I took her out on 6S and ran around normally like I do, and the temps were great as was the rpm and acceleration. The ESC hit about 150. I hit 94mph on the back straight away of the course where I usually only hit low 80's. That is more than sufficient for my purposes. It got there quickly and I had ample room to brake before turning. Would like it to be a little slower. I can not any further compare it to the 1717 1650kv because I only ever ran 23/46 with it. This motor I started out a 27/46 because of the difference in kv.

I hooked up 8S and this is where things changed.... Dramatically. On 8s, I'm looking to keep the rpm at a safer level, while still maintaining what I can only describe as instantaneous 0-90000000000000000000MPH acceleration. I was only interested in seeing how much lower I would be able to keep the RPM with this gearing. The temperature on the motor and esc were great....... about 13 degrees warmer on the motor. I decided to wind it out just to see peak rpm. I wasn't interested in the speed just the rpm, so I turned off my SKYRC gps. At sustained throttle, my car turned into a airplane, did a single back flip, landed on its wheels and kept going. When it touched down, the GPS mount broke (3d printed) and it threw the GPS from the car. I immediately laughed and said to myself, I wasn't using that thing anyway. No damage to the car ( I kept running). The rpm is still a little on the high side, so I may go to a 32 pinion and retest for rpm and temps. I'd like to hover around 45k +/- 500.

This motor is McNasty. No signs of being sluggish or over tasked. The sound the car makes accelerating makes me smile!

Increasing the pinion is going to also increase the amperage load and temps.
My recommendation would be to turn down the throttle on the radio. You could set it up to only offer 80% max.

Maybe set in a throttle curve also? (this can be done in castle link or radio settings)
I find it can be very helpful on 8s to take away the overly crazy low end punch and make the throttle feel a bit more linear (expo 1 or expo 2 in the diagram below).

 

[Malice]

Increasing the pinion is going to also increase the amperage load and temps.
My recommendation would be to turn down the throttle on the radio. You could set it up to only offer 80% max.

Maybe set in a throttle curve also? (this can be done in castle link or radio settings)
I find it can be very helpful on 8s to take away the overly crazy low end punch and make the throttle feel a bit more linear (expo 1 or expo 2 in the diagram below).

View attachment 114747

I thought about that as well!!!! Today I actually opened up castle link and was going to retard it to 80%. I kept bouncing back and forth in my head as to whether or not using the esc as a limiter will be more burdensome on the esc than continuing to increase tooth count. I was going to call Castle today and see if I could speak with a tech to further inquire about that. ( that was my cop-out.....It's too damn cold to be outside "testing.")

I wonder if @robert@castle might be able to speak to the effect on the esc, if any, by using it as a rev limiter.


**edit**
Just a little info. I've been running RC cars since I was a child. I went from resistor type mechanical escs, to novaks and tekins. I quit running cars as a whole in the mid 90s and took up helis, boat and planes. Up until about a year or so ago, everything I ran and still run have been Nitro or Gasoline. I was never a fan of brushless anything. If we're being honest, Im still not but this is where we are today.

Not much of a learning curve, but a curve nonetheless. To limit throttle back in the day (of our cars that we thought were hauling ass at 35-40 mph) we would adjust the end point or adjust the servo (on mechanical) escs. I never did any testing to see if that was harsh or harder on the esc. It was never a consideration, we just did it.

Castle is my first ESC with any type of real programmability. I have no idea how these things work, they just do and I'm thankful for having stumbled across Castle (and Arrma) after years of refusing to convert. The throttle limiting and throttle curve built into the esc are cool, but I'm coming from a place where throttle curves, at least to me, are used for idle up 1&2 and exponential is used to decreasing sensitivity around a certain point, usually neutral. I use them in situations where I fly inverted or am performing aerobatic maneuvers (as engaging idle up 1 or two would also engage my collective(heli) curve as well) on gas or nitro engines.

I don't do electronics. My father is a electrical engineer with two masters degrees, conversely, I hold a MBA and a JD. While I am very mechanically inclined (owned / operated a machine shop and still own the machinery that is set up in my garage) electronics don't excite me at all. I plug it in and I expect it to work. The data logging feature on the Castle escs has me more interested in electronics than I have ever been before in my life. It's funny that toys have made me curious about this stuff. I speak to my father about my logs and his impressions, and they turn in to 4 hour long conversations (which is great!! Hi Dad!) but there are a lot of things I don't know. Now that I feel like I need...or would like to know because of the enjoyment I get out of running these cars, I have thousands of potential questions, some of which I think I know the answer to, but am probably wrong, and some that I will never change my opinion on.

My thought process with using the esc as a limiter is what algorithm or what is going on inside that esc to limit throttle, and whether or not it taxes the system more, less, or not at all. If I can bump the throttle back to let's say 80-90 percent using the esc and not end points with no ill effect then I am done! There is fun to be had in figuring this stuff out on your own and only asking questions after you've exhausted every avenue you can think of (I haven't even started). I think of the esc as a light switch. The lights are either on or they are off. Anything in between, because I simply do not know (and have yet to research) seems that it would require some type of "work" for lack of better terminology on behalf of the esc (I pray one of you tells me I'm wrong before I spend all evening researching this inconsequential fact) which could/would/should/maybe not lead to and increase of heat in the esc. I think it shuts down right around the 212* (MMX8S) mark, which in speaking with castle reps won't come close to damaging the esc internally. If I can get 6-7 minutes of run time (varying thottle position) without the esc overheating, I don't care how I get there or the amount of strain put on any of the components involved. I have that now, but I have higher rpm than I would like. The rpm right around 45k with all four wheels touching the ground, and 6-7 minutes are my only considerations outside of accelerating. The kv of this motor dictates es that I either keep climbing in gears or find another solution outside of running 6s. Hopefully collectively (everyone who reads this, myself included) can answer this and I can direct my attention to crashing!!!!