Mailing List flyrotary@lancaironline.net Message #4194
From: Russell Duffy <13brv3@bellsouth.net>
Subject: radiator at cowl outlet?
Date: Sat, 1 Nov 2003 18:23:12 -0600
To: Flyrotary List <flyrotary@lancaironline.net>
Message
Greetings,
 
I flew again today, and ended up proving that my cowl cheek exits alone (66 sq in) will not be enough for climb, though they may well be enough for cruise.  To add a cowl flap on the bottom, I'd have to leave the radiator low, like it is now, in order to get enough space over the top of the radiator for an exit.  Of course, this is horrible, since air is coming in the radiator, and out the exit right next to it.  There has to be a better way. 
 
Has anyone here put their radiator and oil cooler at the air exit of the cowl?  I know Powersports did this, as well as Atkins I think.  This would be the absolute simplest solution to my problems, if it works.  The new cowl already has two beautiful 24 sq in inlets on the front.  The radiator and oil cooler could be moved up to the bottom of the engine mount, making them fit completely inside the bottom of the new cowl.  The cowl cheeks could be closed up, and faired as Van intended.  All I would have to do is make a large adjustable exit scoop for the bottom of the radiator.  In cruise, this would end up being closed to the point where it would almost be the same as the stock cowl.  In climb, the scoop would be opened quite a bit more to help airflow.  The beauty of this is that the extra drag would only be around during climb, at relatively low airspeeds.  
 
Now of course the problem is the engine and turbo heating the air prior to having it get to the oil cooler, then radiator.  I just have no idea how much it would be heated though.  Can anyone take a swag about how much of a problem this would be?  In other words, how much would the air get heated?  I REALLY could use the new... you-know-what to measure some temps.  Is it November yet :-)  I could measure the air coming out of the back of the radiator/oil cooler now, then measure what comes out of the cowl.  That would give me some idea how much heat is getting added by air flowing over the engine/turbo. 
 
In other news, I'm hearing some second hand whining from some of the guys at the airport.  They claim that my plane is loud, and annoying, though no one has really complained.  I had an RV-8 buddy of mine listen today as I flew around, and he said he didn't see any problem at all.  He thinks it isn't really any louder than the lycomings, but that it's a much different sound (of course).  He said it sounded like a large RC pattern plane with a tuned pipe.   BTW, I'm tired of flying around the airport area.  Tomorrow, I fly to the beach :-)
 
Cheers,
Rusty (hoping for an early Christmas present from Tracy) 
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