Outrunner ?

[tiqueman]

Doing another small "mini" project using an outrunner. small stuff, like using this http://cgi.ebay.com/RC-Model-3650-Ou...t=RC_Modellbau

Whats a good target rpm for small outrunners?

[Simon.O.]

If it is of any help I use a few 450 size Heli motors (27-28mm dia) in my small boats

15.5" Cat 3850kv 37mm long, 3S with a 60A esc to a 427 prop, Faaaast !
13" Cat 4000kv 35mm long. 3S with a 40A esc to a 427 prop, out of control !
18" Semi-saw type rigger 4000kv 35mm long with a 40A esc to a 427 prop, nice but could do better.

The way I run small props anything under 30krpm is just splashing water

[tiqueman]

So youre saying 30K is safe w/ outrunners? Or are you just SAW passing and calling it a run?

[Fluid]

The smaller the outrunner, the higher the rpm limit. Because the magnets are spinning, the further away from the shaft the higher the centrifugal force and the more distortion of the spinning ring of the motor. Here are the approximate rpm limits for Scorpion outrunners.

HK22 - 40,000
HK30 - 35,000
HK40 - 30,000
HK50 - 20,000



.

[Simon.O.]

So youre saying 30K is safe w/ outrunners? Or are you just SAW passing and calling it a run?

For me I am happy with mid-high 30krpm unloaded rpm
I load these small motors with small a small prop and they fair scream. Sound and performance.
As far as run time there are a few variables here.

My 18"cat with a 28mm dia OR runs nuts fast and if I can keep it wet side down i will run back and forth for up to 12 passes (6 circuits) or less than a few minutes run time. Deffo more than a 2 pass rocket.

The 13" cat has yet to do more than 6 passes before sunbathing upside down on the pond.

The 15" rigger is good for about 5 circuits before the pack starts to call it a day.

Now before anyone gets all excited and thinks that this is some definitive data then stop!
I am well different as we all know and run well outside of the crowd.
I am trialing OR motors to see what all the fuss is about and so far like what I see.
Given the price and durability of them I will buy a few more and see what can be done. I am now going to get some with a lower kv and load them with a bit more prop to see what happens.

Bear in mind I have no gps, not that the small hulls would take one, I use my eye and ear to tune......then the finger on the parts when I untape it.

Hope I can help