Brushless CRT Questions

[BrianG]

Cool. I think you'll be happy. What voltage do you plan to run on that? With a kv of 1568, you should have plenty of voltage options.

[Sower]

Exactly. Right now I'll be running it with 14.8 since I'll be using the Mamba Max esc. When the MMM comes out, I'll go to a 5s or 6s. Or more . . . ? Either way, I figured this motor would handle all those options well. With the lighter batteries than GD ran and smaller 1940 motor, I think I'll be about 11 pounds or just under. I think I'm going to be real happy!

[Sower]

Oh, hey BrianG . . . on your motor info you have the 1940 as having a 3.175" shaft when it actually has a 4mm. Unless I read it wrong. FYI.

[BrianG]

Yeah, I've been meaning to update that. I'll do it now. I actually got that info from the lehner site. I guess there must be different shaft options?

EDIT: Updated the 1940's with a 4mm shaft...

[Sower]

Yeah, it caught me off guard since the 1950 was a 4mm. Oh well, Mike straightened me out. :005:

Seriously, your motor calculations and everything is awesome - an excellent resource. Thanks.

[BrianG]

Np. :)

[glassdoctor]

Me thnks a 6s 5000mah maxamps pack would make this truck FLY!!!!! heehee

[BP-Revo]

Originally Posted by Sower

Yeah, it caught me off guard since the 1950 was a 4mm. Oh well, Mike straightened me out. :005:

Seriously, your motor calculations and everything is awesome - an excellent resource. Thanks.

The 1950 is 5mm. 1940 is 4mm, as well as the other 19 series motors (4mm).


Brain, for the Wye vs Delta configuration, I'm not exactly sure which, but one of them increases the KV by 1.73, not decreases. I just don't know which way does what lol...

Nevermind...Wye decreases KV (by reducing voltage by 1.73). When the motor is used as an alternator, Wye boosts voltage by 1.73, while current is reduced by 1.73. So in a motor configuration, its logical that voltage is reduced by 1.73. So I guess this means using wye allows the use of more voltage, since KV will end up being the same...

This is pretty useful.

[Serum]

it depends BP..

A Delta turns 1.73 times quicker per volt than a Wye.

So going from Delta to Wye will decrease the RPM with 1.73 and will increase the torque with 1.73.

Going from Wye to Delta will increase the RPM with 1.73 and decrease the torque with 1.73.

A lehner motor comes as a Delta, and can be configered as a star, resulting in a 1.73 lower KV.

[BrianG]

It is easy to see which is which by looking at a coil diagram. In a D config, voltage is applied across one coil. When in Y config, voltage is applied across 2 coils (but as a vector, which is why it is 1.73x, not 2x). So, in effect, Y config has more turns so kv decreases.

[Serum]

yes, and this would explain the dividing thing; that 1.73 is the result of square root 3.. Get it?

[Sower]

Well, I just ordered the rest of the supplies. Carbon fiber angles for the battery tray, Mamba Max ESC, Hyperion 4s 4350 lipo, BEC . . . I think that's it. Already have the radio. I'll start posting pics as it comes together. I asked Mike to make a motor mount for me a couple times - no response. Oh well, I guess I'll just have to make one myself. Does anyone have a spare motor mount for the CRT? :027:

[Sower]

Ok guys, I'm close to completion. I'm still waiting for my carbon fiber angles to make my battery tray, and I'll clean up a couple other things . . . but it's driveable. I took it out last night in the street and it's sick! It surpasses my expectations. I just wanted to thank everyone here for their help. Serum, GD, BrianG, BP, Jolly, Squee, Mike, and of course thanks to the academy.

Seriously though, thanks everyone. I'm stoked. Check out the photos of the temporary setup. Please keep in mind that the batery will not be held in place by the hairline ziptie shown in the pics. I hope that CF gets here today.

Oh, for any of you wondering, here's what I have in it:

Lehner 1940/10 Hi-amp with Kyosho 44t spur and 15t pinion
Hyperion 4s 4350 li-po
Airtronics 94359 (this thing is sick on 6v!!!)
Dimension Engineering 6v BEC (look closely and you'll see it by the motor - tiny!)
Mamba Max ESC
Spektrum SR3000
And of course, it's a Jammin CRT Pro chassis

[Sower]

I guess now that I look at the photos - you can't see the BEC :005:

Well, it's small and works awesome. Here's a link for anyone that wants more info on it:

http://www.dimensionengineering.com/SportBEC.htm

[Sower]

Here's some close ups of the ESC and BEC. I will mount the ESC to CF when it arrives, and make a CF cradle for the back of the Lehner too.