18" or close Mini-Cat

[Simon.O.]

As some of you know I need to replace my mid size cat. That was a 25"ish hull and is now on the shelf forever.

I have a new plan !!
I will build a 18" and a 12-13" at the same time. Now we all know that these will be a little longer loa as I like the long rear overhang and I also like a prop set well aft too.

The little one should get a 380 size Inrunner on 2 or 3S to a small M4 graupner prop.

Here is the bigger question. For a hull similar in size to the Minicat Racing Velocity Cat.
Do I go for an outrunner (OR) like this.

http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=9257

Or an inrunner (IR) like this

http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=5145

Both can provide me with the power (W) that I need, the esc and packs is the easy bit, I will provide the motor with plenty of energy.

What I need to know is if a single outrunner is suitable in such a small hull.
I can do either motor and will spin a small prop fast regardless.

OR or IR ??

Votes and reasons please.

[CornelP]

You're probably safer with the small IR, as you will not have too much space for ventilation in the hull. I tried the OR in my ECO for the last race and I failed miserably... I wanted to be safe for battery time, but I lost big time on speed... after 6min, I could not touch the can for more than a second...

[Simon.O.]

Cornel, that is interesting info and may sway my decision.
I'll wait a few days to see if I get some more opinions.

There will be a question on a smaller cat motor soon too.
I plan on building both at the same time.

and then painting all 3 at once

[Jesse J]

Hey Simon, I thought I would copy the info I gave you in pm here too:

Motors. Simon, the inventor/on the fly inventor, I think you owe it to yourself and us to get both motors and do a real study on IR vs. OR and torque roll. If I were Simon O., I would get both. My first instinct is to go IR (cooling and possibly power and durability). I have had OR trouble in that since the can is spinning around it AND potentially more importantly, they are designed as PULLERS, the can can loosen and actually be pushed off the back. This can most likely be prevented with a thrust bearing.

I think you are in the ballpark for KV, I like 3000KV on 3S (we've had this discussion), and I think your target set up ought to have good chances of success.