[NSRCA-discussion] Cooling outrunners

[Dean Pappas]

Bob, you're a genius!
I suggested this to an E-powered CL Stunt buddy in the Netherlands some months ago because the Stunt guys have a long history of styling planes with chin scoops placed far back. These often require a 3/4" long prop drive extension to place the cylinder back farther, and the use of a short venturi. They cowl much easier than computer carbs!
 
Hi Chad,
Makes you wonder what some of these guys were thinking when they placed the cooling and cheek inlets. ?? **^^$$!!!
The inlet airbox can shroud the aft end of the motor and the sleeve dump into a front exit plenumm. Now the trick is the exit from there. I think that a big elbow like a turbopropo exhaust would be cool, as would be cheek cowls with no entry holes just exits. The exit plenum just behind the spinner would have to duct into the cheeks. Notre that flying without a spinner will wreck the cooling! A row of exhaust stacks like a P-51 could be boxed in and used to suck the warm air out of the exit plenum. I need to draw a picture. That'll take a while, especially around Christmas.
 
The colder the magnets are, the stronger they are, and the less resistive the copper is, so cooler is always better for the motor. The same is true for the ESC: MOSFETs are less resistive the cooler they are, so everything gets better in the Antarctic except battery performance.
 
later,
    Dean
 
 

Dean Pappas 
Sr. Design Engineer 
Kodeos Communications 
111 Corporate Blvd. 
South Plainfield, N.J. 07080 
(908) 222-7817 phone 
(908) 222-2392 fax 
d.pappas at kodeos.com 

-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org [mailto:nsrca-discussion-bounces at lists.nsrca.org]On Behalf Of Bob Richards
Sent: Tuesday, December 19, 2006 9:27 AM
To: chad at f3acanada.org; NSRCA Mailing List
Subject: Re: [NSRCA-discussion] Cooling outrunners


Is there any reason why you can't duct the air to blow into the rear of the motor, and provide a way for it to escape from the front?
 
Geez, I'm just thinking that leaving the spinner off, or use a really small spinner, would be the way to go.
 
Bob R.


Chad Northeast <chad at f3acanada.org> wrote:

The problem with a lot of composite fuse models (Twister included) is 
that the inlets in the chin and cheeks are often right at the rear or 
even behind an outrunner.....so ducting toward them is very difficult. 
I have to agree that a proper ducting system is crucial for cooling. I 
use a very simple short radius 90 bend in a peice of depron that pulls 
air in from the chin, I see about a 20C rise in temp without it, other 
than that I dont really do anything special. The motor will operate at 
up to 170F without complaining so as long as its 20-30F below that all 
is good :)

Chad



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