Why aren't cars using outrunner motors?

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Atomic Skull

Atomic Skull

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Big helis have been using outrunners with a centrifugal fan built into the motor bell for decades now, they have a similar problem a large powerful motor in an enclosed space. The fan draws air through the motor windings and spits it out. This seems to solve the heat dissipation problem without the need for a fan. why haven't cars picked up on this idea yet?
 
Atomic Skull said:
Big helis have been using outrunners with a centrifugal fan built into the motor bell for decades now, they have a similar problem a large powerful motor in an enclosed space. The fan draws air through the motor windings and spits it out. This seems to solve the heat dissipation problem without the need for a fan. why haven't cars picked up on this idea yet?
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You can do it but likely to end up in a pile of smoke. Innovation rc done it recently

 
Fewer cells more amps, motor couldn't handle it. It was barely getting warm on 6S. Don't run a heli motor made for 6S~8S on 4S. If there were car specific outrunners this could be addressed with more appropriate KV motors.
 
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Atomic Skull said:
Fewer cells more amps, motor couldn't handle it. It was barely getting warm on 6S. Don't run a heli motor made for 6S~8S on 4S. If there were car specific outrunners this could be addressed with more appropriate KV motors.
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I can’t answer on cars but medium sized Heli and Jets I have a lot of time with outrunner and inrunners. For jets up until recently your smaller EDF motors were all outrunners with most larger brands 70mm and above being inrunners. Outrunners by far are harder on packs on one I modified a outrunner I could only get 3min of flight time once I swapped to a inrunner 3:30 to 4min were achieved. Most outrunners have better lower torque with inrunners producing more top end speed. Even now they are swapping all the way down to 40mm outrunners to the inrunners increasing performance. I think personally the inrunner is more efficient giving more play time and performance

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You can see out runners used in Hosim RC trucks and they seem to get hot fairly quickly, although they do provide decent amounts of power.
The thing is (in my opinion) the helicopter and drone outrunners have a lot of ambient airflow cooling them down. Underneath the shell of an RC land vehicle, there is much less fresh air flow.
Thus, cool air must be added, yet there is no easy way to add supplemental cooling to an outrunner motor in a land RC.
Can't mount a heatsink and a fan would take considerably more space to be mounted vertically and aimed at the outrunner.
Also, debris intrusion poses an issue, I'd imagine.
These are just my assumptions, based on the few Hosim outrunner motor land RCs I've seen on @Derby City RC and @Rek RC on YouTube.
Also, the big issue of MOUNTING the outrunner. The only spot for supporting it is from the end of the can. I know a lot of RC manufacturers simply mount at the end of the can, but the outrunner motor needs considerably more room to avoid contacting the chassis \ other parts of the RC while in motion. Not to mention wires, etc...
The Hosim uses a janky outrunner mount that bent fairly easily.
I don't think the outrunner motors have a thick enough "can" to be mounted in a land vehicle that's going to be jumping and tumbling.
 
Definitely with the outside of the housing spinning just a bad idea in a closed area like a car with little airflow
 
Think the conditions most rc cars/trucks run in ie off road just not suitable the dirt & dust that get inside them would just destroy it in no time & off road on bumpy or grassy terrain they extra load on them they’d cook in no time on smooth surface maybe get away with it but would lack the torque of a bigger can off road.
 
The most efficent brushless motors out there are the
shortround9191 said:
Definitely with the outside of the housing spinning just a bad idea in a closed area like a car with little airflow
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Helicopters have been doing that for ages, they put a centrifugal fan in the end of the motor bell. Those holes in the top of the rotor are the fan when the motor spins it pulls air into the bottom of the motor and through the windings and spits it out the top.

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Question on the Spark guys I ran her yesterday all great installed the 7075 diff case. Have seen videos some turning up the setting for the servo voltage. Should I leave that stock setting unless I replace the servo?? I need to find somewhere that I can actually have some fun with the Spark no jumps at the club yet but she’s a beast of a truck

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shortround9191 said:
Question on the Spark guys I ran her yesterday all great installed the 7075 diff case. Have seen videos some turning up the setting for the servo voltage. Should I leave that stock setting unless I replace the servo?? I need to find somewhere that I can actually have some fun with the Spark no jumps at the club yet but she’s a beast of a truck

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The stock servo can take 7.4v, so you can change the esc setting to 7.4v if you want.
Since the stock setting on the esc is 6v, I assume is playing it safe for a longer lifespan.
I’d set it to 7.4v and keep a good/better (and way way cheaper) Aliexpress servo in your spare parts box.😉
 
I posted in another spot that I’ve gotten spoiled with the little time playing with the Spark compared to the Kagama4. The Kagama steering is just sluggish compared to the Spark, any suggestions on the Kagama4 to get better turn radius from it before I just ordering Kagama6 steering parts and I’ve seen the aluminum servo savers not sure if they would help steering again so new to this. I don’t mind buying but want to buy smart not stupidly.
 
shortround9191 said:
I posted in another spot that I’ve gotten spoiled with the little time playing with the Spark compared to the Kagama4. The Kagama steering is just sluggish compared to the Spark, any suggestions on the Kagama4 to get better turn radius from it before I just ordering Kagama6 steering parts and I’ve seen the aluminum servo savers not sure if they would help steering again so new to this. I don’t mind buying but want to buy smart not stupidly.
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An upgrade servo will give a faster steering response. Tightning the servo saver spring may also help, downside of that is less servo protection during a crash.
Comparing the Spark to a Kagama is bit of apples to oranges thouigh. Spark is a track buggy, Kagama a Monster Truck. You’ll never get the same feeling, but that’s that why you have both cars!😆
 
You’re definitely right there, a curse I have can’t ever leave anything alone ever. I wanted to do some speed runs on the Kagama4 but I can’t get enough satellites to get a read. Have to try again next time I head to the club
 
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