Lowering BL Revo CoG.

[suicideneil]

I dunno if an outrunner for racing would be ideal- the spool up time is much slower compared to an inrunner I believe, so that would mean poor acceleration down the straights and out of corners, just when you need it most. I might be lying though...

[zeropointbug]

Hmmm, all I need is 4 digital scales now... ... I have one legal for trade 10lb unit, which I just weight the components and place them on the chassis and hold the truck in the center of the skidplates and see if it holds level. I do it by eye as well. There has got to be more to weight distribution than just static balance me thinks... a sort of 'dynamic' balance, where even though it is balanced for weight, components might be all wonky all over the place that it causes certain 'inertial' effects when in action, thus not being 'truly' balanced.


Neil, true, that might be a valid point... it might be unbearable going from a fast spooling 1512 to a high inertia outrunner. Although, I don't think it would affect it in the straight, I would think more in the tight technical parts where you need quick power to the wheels for mere milliseconds.

Sike! Calling Sike on this one!

If I could get an outrunner to work well in the Revo for racing, and lowering the batteries... I am pretty sure I could beat all the truggy drivers except two at our track.

[sikeston34m]

Hi Guys,

Always glad to lend a hand when I can.

Here's some reference material. http://www.rc-monster.com/forum/show...ect+drive+diff

Am I still using the outrunner in my truck? No, but I still have all the parts here.

I ran into two problems with the direct drive to diff setup:

#1. 4.6:1 final diff drive ratio gears would NOT hold up to the torque being made. The diffs use ball bearings not thrust bearings on the pinion gear. I could trash the pinion bearings in less than one packs runtime. Yes, they were shimmed properly. It would always punch the center race right through the outer race. Little balls everywhere. LOL

#2. In an effort to get the kind of speed/power I wanted, a custom wound outrunner was created. An AXI 4130 was made into a 4 turn motor. Hot Thing! but would pull HUGE amp spikes on startup.

It still wasn't too shabby:

http://www.youtube.com/watch?v=dFDrYXLkcGg

Check out the video, then ask yourself if this has "spool up" problems.

Spool up time is required or negated by final drive ratio. It all depends on how much torque the motor makes. High Revving motors use very low gearing to make up for their lack of torque. The same applies in reverse for outrunners.

How do you plan on gearing your setup Seth? And what voltage do you plan on running?

[sikeston34m]

Thanks for the PM Seth. Please feel free to include me on ANY discussions of this sort. I LOVE it. LOL

[sikeston34m]

More Reference Material:

http://www.rc-monster.com/forum/show...light=axi+maxx

Check out the setup and the vids in this thread.

Such Torque from such a small outrunner.

[zeropointbug]

beauty, thanks for posting Sike.

I would run 6s, so the 330 Kv. of the scorpion motor would equate to 45mph, not too much faster than the 40mph it's geared for at my track, which is perfect. (we have a long straight section)

If they have a 300Kv., that would be ideal, but they have a big gap in their Kv's to choose from.

I was also thinking about a truggy center diff, but the Revo diffs are too high of a ratio to be used with one, you would need hybrid diffs.

Q1: What diffs were you using to blow the bearings? And how would an inrunner/trans setup be any different in that respect?

Q2: Simply, what do you think of the motor in question? Think it will be suitable?

If this did work, then the handling on the truck would be in short, sick. I would be able to keep up with truggies no problem, as I can keep up to most of them even with the high CG as it is now.

[sikeston34m]

Originally Posted by zeropointbug

beauty, thanks for posting Sike.

I would run 6s, so the 330 Kv. of the scorpion motor would equate to 45mph, not too much faster than the 40mph it's geared for at my track, which is perfect. (we have a long straight section)

If they have a 300Kv., that would be ideal, but they have a big gap in their Kv's to choose from.

I was also thinking about a truggy center diff, but the Revo diffs are too high of a ratio to be used with one, you would need hybrid diffs.

Q1: What diffs were you using to blow the bearings? And how would an inrunner/trans setup be any different in that respect?

Q2: Simply, what do you think of the motor in question? Think it will be suitable?

If this did work, then the handling on the truck would be in short, sick. I would be able to keep up with truggies no problem, as I can keep up to most of them even with the high CG as it is now.

Q1. I was using the RCM v2 Hybrid Diffs. Difference = Direct Drive. No Slipper. Diff Torture Chamber!

Q2. Scorpion Motors are well built, but they have little or no fan. This makes it harder for them to shed their heat, especially in a rolling application. Flyboys mount them behind the biggest fan possible, so it works well.

Any Motor makes heat especially when pushed. If your mount and frame are aluminum, you might have enough mass to shed heat.

This is why I went with AXI. They do sell a fan that mounts to it's rotating endbell. It moves alot of air too.

I've been tempted to go with Mike's Slipperential. Put that together with regular straight cut gears in the diffs. An Outrunner geared properly would work very well.

For gearing, think outside the box somewhat. Go by the gearing calculator and even then, the outrunner has the torque to pull higher gearing than it suggests.