[NSRCA-discussion] Cooling outrunners

[Adam Glatt]

Dean, for what it's worth, Thunder Power now recommends the eXtreme 
Series packs for F3A (and pretty much everything else).  I think this is 
primarily because they believe they will have to warranty fewer 
batteries; the eXtreme cells are more robust.  For 2007 they are 
recommending the new 10s 5000mAh eXtreme Series pack.  It will sell for 
something like $580.

Masters and below might be better off with a smaller eXtreme Series 
pack.  I've seen the discharge curve for the 5000mAh at 25C (125A!!!), 
and it shows a long time at 3.4V and about 80% above 3.3V, so a even 
smaller pack will have no problem putting out the 60-80A we use.

-Adam

Dean Pappas wrote:
> Hi again Chad,
> So do you have a decision as to whether you are changing over to the Extremes or staying with the 5300 Pro-Lites?
> >From what I gather, it may not be a clear-cut decision.
> 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 Chad
> Northeast
> Sent: Wednesday, December 20, 2006 12:37 AM
> To: NSRCA Mailing List
> Subject: Re: [NSRCA-discussion] Cooling outrunners
>
>
> Hi Dean
>
> Quite true about the magnets, but I have flown with my motor at 150F and 
> on days where it doesnt get above 65F....I can not tell the difference 
> in performance, probably because there is such excess power in these 
> setups to start with.
>
> Pack temperature on the other hand is very important, OAT below 10-15C I 
> have to start restricting cooling on the batteries or they dont get warm 
> enough to provide good power.  The new extreme packs are better about 
> this than the Prolites, but still very noticeable on certain days.
>
> Chad
>
> Dean Pappas wrote:
>   
>> 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