Lowering BL Revo CoG.

[zeropointbug]

You are blowing diffs without a slipper? I have my slipper tightened all the way down and I have not had any problems yet. Just have to let off throttle at the right time I guess? It took me 2 years to blow a diff with slipper tightened 100%.

-Have you ran a scorpion motor in the direct outrunner project? If so, which one?

I am sure the outrunner will get enough cooling to keep it within the safe temp range... I don't really care about temps at this point, I just want to test the waters and see if I like the concept, as I always have wanted to do this, but am reluctant in the end.

One thing I don't get is the power rating, 2400watts cont. for a 440g motor? Come on, doesn't a 1515 weight almost that, and it has a 1500watt rating. Unless it's typo, or it's the max watts rating, I highly doubt it.

So the motor/trans that is in the truck now is 470g, I would save a small 30g, but the CG would be very low.

If I can find a way to lower the trans (G1 single speed) and make a seperate motor mount to lower the motor, then I would obviously keep using the Neu. But the outrunner just seems alot easier to accomplish this.

It's times like these when you just hate the setup of the Revo with the shocks taking up over half the room.

[sikeston34m]

[COLOR=[/B][/COLOR]

Originally Posted by zeropointbug

You are blowing diffs without a slipper? I have my slipper tightened all the way down and I have not had any problems yet. Just have to let off throttle at the right time I guess? It took me 2 years to blow a diff with slipper tightened 100%.

We're talking some explosive High Geared Torque coming from an Outrunner here. So Yes, the lack of a slipper is partially to blame for the problems. If there were a slipper, it could have been utilized with the setup. Inrunners don't have this type of Torque Period.

-Have you ran a scorpion motor in the direct outrunner project? If so, which one?
No I haven't. When you choose your Outrunner, whichever one it is, seep some additional RED or GREEN Loctite in between the Stator and the Bearing Holder. This is a weak spot if you run it as is. They don't put enough.

I am sure the outrunner will get enough cooling to keep it within the safe temp range... I don't really care about temps at this point, I just want to test the waters and see if I like the concept, as I always have wanted to do this, but am reluctant in the end.

One thing I don't get is the power rating, 2400watts cont. for a 440g motor? Come on, doesn't a 1515 weight almost that, and it has a 1500watt rating. Unless it's typo, or it's the max watts rating, I highly doubt it.

There's a difference in the "flyboy" rating and our Land Vehicles. The Most Major one is airflow. The ability to shed heat is one thing that affects ratings alot.

So the motor/trans that is in the truck now is 470g, I would save a small 30g, but the CG would be very low.

If I can find a way to lower the trans (G1 single speed) and make a seperate motor mount to lower the motor, then I would obviously keep using the Neu. But the outrunner just seems alot easier to accomplish this.

It's times like these when you just hate the setup of the Revo with the shocks taking up over half the room.

Yes, the Revo is VERY cramped.

It's alot to think about isn't it?

[zeropointbug]

We're talking some explosive High Geared Torque coming from an Outrunner here. So Yes, the lack of a slipper is partially to blame for the problems. If there were a slipper, it could have been utilized with the setup. Inrunners don't have this type of Torque Period.

-IMO, I don't think that would matter would it? I mean if it's an inrunner of equal power is geared for the same speed, then the torque to the diffs would be the same, as all brushless motors have to the same torque curve (straight line)... and yah, it's too bad that any type of slipper can't be used with a setup like this.

There's a difference in the "flyboy" rating and our Land Vehicles. The Most Major one is airflow. The ability to shed heat is one thing that affects ratings alot.

-Completely agree with you on this one, cooling is basically the limitation to the continuous wattage rating (to a point), the better the cooling the closer the continuous rating will be to the peak rating. But still, that said, 2400watts for 440g is huge, so maybe the rating is taking into account that the components they use can handle high temperatures? However, that does not mean the efficiency would be very good at that output, if anything below average, maybe 85% or lower, whereas a Neu, IIRC, is roughly almost 90% efficient at it's rated output.


Another thought... I was just moving stuff around on the truck and was tilting the transmission 45 degrees one way and putting the motor centered in the chassis. Now if only I could make it work that way without heavily modifying the chassis to make room for it. If it could be done, then the motor would be centered, trans tilted to the left with steering servo on left as well, with Rx/rx batt on right side, and then twin packs on each side, should be 99% balanced then. Still thinkin on the ideas though.

[sikeston34m]

Originally Posted by zeropointbug

-IMO, I don't think that would matter would it? I mean if it's an inrunner of equal power is geared for the same speed, then the torque to the diffs would be the same, as all brushless motors have to the same torque curve (straight line)... and yah, it's too bad that any type of slipper can't be used with a setup like this.

I think there are some major differences between outrunners and inrunners in how they make power. The Gap between the two used to be large when I first got into discussions about this. Those were the days of the two pole inrunners.

The Gap has been closed somewhat with the rising popularity of 4 pole inrunners. (I LOVE 4 pole motors btw)

Ok, Let me explain my thoughts as best I can, this way.

What makes power in an electric motor? Any motor?

It is the repelling/attracting forces of the magnetism. Correct?

How much power we can make depends on the strength of the attracting or opposing magnetism. Correct?

So in the Engineering World for Motors, one would think the bigger/stronger the magnets AND the stronger the electromagnetic field is, then the more overall power is going to be produced.

Bigger is More!? Well yeah. But we only have so much space to work with, right?

This is where I feel the outrunner shines.

Measure the stator on an outrunner. I believe an inrunner would be required to have a rotor almost this big to make the same amount of torque simply because of the obvious leverage advantage.

Now, consider the total mass of the magnets spinning inside the outrunner's can. Think about how large an inrunner's rotor would have to be to contain the same magnet mass.

Then let's add up the poles. A 12 pole motor shaft shifts 30 degrees for every commutation from the ESC. This is where the lower kv comes in, BUT there's a torque multiplier at work here too.

How many degrees does the shaft shift on a 4 pole motor? To be honest, I would have to look it up, but it's alot more.

Long Story Short, the outrunner makes its power at a much lower rpm, but it's still all there. Condensed Power at a much lower rpm. This is what I was calling "Explosive".

Where as, the inrunner makes it's power through it's ramp up (spool up) time, and much higher rpm.

Another thought... I was just moving stuff around on the truck and was tilting the transmission 45 degrees one way and putting the motor centered in the chassis. Now if only I could make it work that way without heavily modifying the chassis to make room for it. If it could be done, then the motor would be centered, trans tilted to the left with steering servo on left as well, with Rx/rx batt on right side, and then twin packs on each side, should be 99% balanced then. Still thinkin on the ideas though.

I think what you're doing is great. Please share more and take some pictures.

[zeropointbug]

Well, I don't know what you think 'kind' of power an outrunner has, all I know is that an electric motor has watts, and the wattage is a product of speed vs. torque, and every motor has 100% torque at zero rpm and drops from 0rpm to max rpm. I really don't think there is anything different in an outrunner, except for motor inertia (although it's spinning alot slower, so that is near canceled out), it has many times more torque, but spins many times slower, so power ends up being the same as well.

Unless I didn't get the idea you were trying to convey? Explain in more detail?


On a side note, I posted some pics of roughly what I was thinking of when I said tilting the trans and making a mount for the motor in the center of the chassis, and lowering it. Check it out. Looks like a pretty balanced setup?

[zeropointbug]

The batteries would be mounted on CF angle mounts and will be sitting 1 inch lower than in the picture.

[sikeston34m]

Originally Posted by zeropointbug

Well, I don't know what you think 'kind' of power an outrunner has, all I know is that an electric motor has watts, and the wattage is a product of speed vs. torque, and every motor has 100% torque at zero rpm and drops from 0rpm to max rpm. I really don't think there is anything different in an outrunner, except for motor inertia (although it's spinning alot slower, so that is near canceled out), it has many times more torque, but spins many times slower, so power ends up being the same as well.

Unless I didn't get the idea you were trying to convey? Explain in more detail?


On a side note, I posted some pics of roughly what I was thinking of when I said tilting the trans and making a mount for the motor in the center of the chassis, and lowering it. Check it out. Looks like a pretty balanced setup?

yep, Watts is Watts but could there be something more? LOL

KV versus gearing versus final efficiency rating. I get that.

That's an interesting way to look at tranny position. I like that, but how are you going to secure it?

This should be good.

[zeropointbug]

Isn't there a website that is going to be doing dyno tests for popular motors in R/C? That would put this debate to rest I think, just to see a torque/power curve of some of these motors. Another thought, maybe it's the ESC firmware that is causing a different 'feel' or level of power between a in and outrunner type?

As for the mounting of the transmision, I was thinking about getting a small bracket made that screws into the aluminum plate on the trans and goes around and mounts like the regular plastic stand-offs. I would have to grind the plastic mounts away of course.