Mailing List flyrotary@lancaironline.net Message #2957
From: Russell Duffy <13brv3@bellsouth.net>
Subject: RE: [FlyRotary] Re: Good news, Bad news
Date: Sat, 13 Sep 2003 23:08:12 -0500
To: 'Rotary motors in aircraft' <flyrotary@lancaironline.net>
Message
Have you tested climb rate at lower speeds, where drag is less important? Also, you could try reducing the size of the inlet to the Radiator scoop to see if that reduces cooling drag, since you have excess cooling available. 
 
On the average RV-#, best rate of climb is about 100 kts, or 120 mph.  That's what it was on my RV-8, and also on a friend's RV-3.  I'm seeing best climb rate down around 80 kts, which was about the best angle of climb on my RV-8.  I think this is an indication that drag is becoming too much of a factor in the higher speed climbs.  There's no questioning the airframe.  The normal performance of an RV-3 is well known.  I also can't doubt the power the engine is putting out.  It really slams you back in the seat on takeoff.  I think the only logical conclusion is that there's an overwhelming amount of drag from the cowl.
 
As for the cooling drag, I do have a huge opening for an air intake, but I just can't imagine that being the majority of the problem.  I'm afraid the whole cowl will need to be re-worked, which means a smaller radiator, and a new intake manifold.  I just don't see any other option, since I'm really not interested in flying it like it is. 
 
Cheers,
Rusty   
Subscribe (FEED) Subscribe (DIGEST) Subscribe (INDEX) Unsubscribe Mail to Listmaster