Cowl baffling

[Dean Pappas]

Hi Ed,
Gas does less evaporative cooling going into the engine, than alchohol, and it burns hotter. On top of that, as John mentions, the reduced oil carries away less heat. My old 3W60 with alky is tough to get warmed up fully, on a cold day! So the reason that you see very little care taken with Pattern ships is due to the forgiving nature of alchohol fuel. If we were racing, then we would carefully minimize cooling drag and proper ducting would be the order of the day. My last hard-mounted ship had such tight ducting, with a small intake and relatively small exhaust opening. I never had a cooling problem, though we weren't torque rolling for laughs at the end of every flight, back then.
Regards,
Dean P.

-----Original Message-----
From: John Ferrell [mailto:johnferrell at earthlink.net]
Sent: Wednesday, March 24, 2004 2:57 PM
To: discussion at nsrca.org
Subject: Re: Cowl baffling


Don't gasoline engines use a lot lower oil mix ratio? I think an awfull lot of heat goes out with the exhaust oil. 
 
John Ferrell    
http://DixieNC.US


----- Original Message ----- 
From: Ed Alt <mailto:Ed_Alt at hotmail.com>  
To: discussion at nsrca.org 
Sent: Saturday, March 20, 2004 9:53 PM
Subject: Cowl baffling

Just wondering what's commonly done to direct proper airflow in pattern birds with 2C engines.  I'm used to creating very close fitting baffling to direct air right at the cylinders of large 2 cycle gasoline fed engines and keeping the baffling so close to the fins as to force it through them.  Even the space over the heads is baffled to force air through the head fins.  After that, I make the area of the air exhaust opening at least 3X that of the total intake area.  
 
So far, in studying various setups of pattern ships, I haven't seen anyone going to this kind of trouble.  Not wishing to go to any uneccesary work, but is there a reason why no one adds baffling for 2C glow engines?  I've got a Focus II with a Webra 1.60 if that helps with the answer.
 
Thanks
Ed

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