Upcoming Castle Outrunner Motors

[Sammus]

So what's the advantage of outrunners? It's been said a few times that for their size theyre not as powerful as inrunners... it cant be the kv because you could just wind up an in runner to get super low kv... so what is it then? are they somehow heaps more efficent or something?

Why do people love running them in cars so much? IT seems lik inrunners are much better suited.

[rotary rocket]

It seems to me that if outrunners have a lot of torque you could use it to your advantage and get rid of the center diff. This would save weight and should result in a more efficient overall drive line.

Of course you would pick a much lower RPM motor and you wouldn't have much flexibility in changing your speed if you use it in place of the center diff.

CC, would you be able to make your motors such that the center shaft is sticking out of both ends?

[MetalMan]

Originally Posted by Sammus

So what's the advantage of outrunners? It's been said a few times that for their size theyre not as powerful as inrunners... it cant be the kv because you could just wind up an in runner to get super low kv... so what is it then? are they somehow heaps more efficent or something?

Why do people love running them in cars so much? IT seems lik inrunners are much better suited.

rr did a pretty good job of summing up why the average outrunner user would choose an outrunner over an inrunner.

For me, it's also the uniqueness factor. TBH, I have this weird drive the almost forces me to do things differently. Just as an example, I am presently working on a belt-drive conversion of a truggy... that also will use an outrunner most likely.

[Sammus]

But more torque isn't a reason, if you wound an inrunner to have the same super low kv as an ourtunner, it would also have huge amounts of torque. Thus I can only imagine it's to do with the efficiency of the motor...

[sikeston34m]

Originally Posted by Sammus

But more torque isn't a reason, if you wound an inrunner to have the same super low kv as an ourtunner, it would also have huge amounts of torque. Thus I can only imagine it's to do with the efficiency of the motor...

A super low kv inrunner would make ALOT more torque. But you also have to consider the pole count.

Most outrunners are 12 pole motors.

The inrunner would also need a larger diameter armature to match the torque of the outrunner.

[RC-Monster Mike]

As a general rule, as the motors pole count goes up, the "efficiency window" gets smaller. Most out runners have high pole counts, which means there "sweet spot" for ideal operation is significantly smaller than the 2pole and 4 pole motors typically used. They are great in aircraft - high torque and a much lower degree of varying power. Cars/trucks are usually run throughout a wider and more variable range of throttle input, so they are best served with a wide efficiency window. A good outrunner is quite efficient when used in its intended range.

[Sammus]

Cool, so I've been convinced that outrunners aren't worth running in cars, as I originally suspected :p

[Metallover]

No, you can't just say that. They work great in cars. I have an outrunner. It's efficient as anything. It's pretty quick too.

[Sammus]

What, I can't say that I've been convinced they're not worth running in cars?

I can say I'm convinced of whatever I want, thanks.

And fyi, I never said they wouldnt run well and quick, but it seems like for any outrunner powered car, there's an inrunner that will do a better job (power/efficiency wise, maybe not easy of mounting).

[lincpimp]

Originally Posted by Sammus

What, I can't say that I've been convinced they're not worth running in cars?

I can say I'm convinced of whatever I want, thanks.

And fyi, I never said they wouldnt run well and quick, but it seems like for any outrunner powered car, there's an inrunner that will do a better job (power/efficiency wise, maybe not easy of mounting).

An outrunner in place of the center diff does have some benefits, but the lack of a slipper and any sort of primary gearing will deter most. I personally think that inrunners, or possibly a hybrid motor, will suit most racing and higher speed cars better.

Now an outrunner in a crawler is much better than an inrunner due to torque. I have a few outrunner crawlers and they are beasts. They are geared low. 10mph max, and only run 3s lipo. Much better than an inrunner, and more power than a brushed motor.

It all depends on what you need.

[Sammus]

Originally Posted by lincpimp

An outrunner in place of the center diff does have some benefits, but the lack of a slipper and any sort of primary gearing will deter most. I personally think that inrunners, or possibly a hybrid motor, will suit most racing and higher speed cars better.

Now an outrunner in a crawler is much better than an inrunner due to torque. I have a few outrunner crawlers and they are beasts. They are geared low. 10mph max, and only run 3s lipo. Much better than an inrunner, and more power than a brushed motor.

It all depends on what you need.

when sik said "A super low kv inrunner would make ALOT more torque" I thought he mean than an equivalent size/kv outrunner. Now I think I may have misinterpreted his response.

At any rate, it was Mike's narrow window of efficiency thing that got me. I want my cars to be efficient in as wide a band as possible. I think even when crawling you vary the motor speed coniderabley.

So where is the trade off? a 4 pole inrunner and 12 pole outrunner, of similar size and Kv. The inrunner I guess makes more power and can rev harder without anything going wrong. The inrunner is efficient over a much wider rpm range than the outrunner. The inrunner can run on a much higher voltage than the outrunner because its max rpm is a lot higher. The outrunner has more torque.

How much more torque? Te inrunner would have like a million winds to get into the 500kv zone so would have heaps more torque at the rotor than any inrunner we're used to. Furthermore, since the inrunner revs so much harder, gear the inrunner down to get the same rpm as the outrunner, you further multiple the torque.

Has anyone got any torque or power curves comparing similar sized motors?

The only application I can find them useful is in airplanes...when rpm is nearly constant, and everything has to be lightweight, so best do without the gearbox (ie low kv is an advantage).

Don't get me wrong, I don't want to argue for the sake of it, I am genuinely interested. But noone has really given anything more than their opinion on why they might of advantage in a car. A few claims that weren't backed up.

Also, I'm not knocking castle either, since I'm certain these outrunners are for their air guys (us car people aren't the only ones obsessed with castle gear you know :P)

[MetalMan]

Yes, you are entitled to your own opinion . Some of us just like to be different. And while you might not see the benefits as we do, that's fine.

[Takedown]

Heres another pic I shot during the I-Hobby Expo Last year...

[Metallover]

you're still greatly biased. Look at some watt figures. Outrunners will be very similar to inrunners. Compare an Axi or Scorpion outrunner to a Medusa or Neu motor of the same size. Remember the Neu 15xx series are 39mm in diameter...

[lincpimp]

Torque output and ability can be directly related to the rotating portion of the motor, and its diameter. Outrunners cannot rev as high due to their design. However they produce more torque at lower rpm, due to the diameter and pole count.

It all depends what you want. If you need something slow revving with alot of torque then an outrunner is great. If you need a large rpm window, then get an inrunner.

I use quite a few outrunners, but still with transmissions. I have also done a few direct to diff conversions where the outrunner replaces the primary gearing. Those pose problems as well, such as high startup loads, and they generally do not spool up as fast as an inrunner (mainly due to the lack of gear reduction).

For most the normal setup of an inrunner and primary gearing will suit them better. For those of us that like to use outrunners, well, we will continue using them...