Mailing List flyrotary@lancaironline.net Message #60192
From: Steven W. Boese <SBoese@uwyo.edu>
Subject: RE: [FlyRotary] First Flight jitters
Date: Mon, 9 Sep 2013 06:43:03 +0000
To: Rotary motors in aircraft <flyrotary@lancaironline.net>

4000 RPM at 32" MAP caught my attention.  With a typical propeller for a 2.18/1 reduction drive and NA 13B, I get about 5200 RPM at 30" MAP at sea level.  This static RPM of 5200 is also very close to what I get at my airport elevation of 7200 ft with 23" MAP.  The air density appears to affect both the prop and the engine similarly.  The RV6A flies well under these conditions.

 

When turbocharging the same 13B engine and prop combination at 7200 ft elevation, I get 5200 static RPM at 30" MAP and 6100 RPM at 37" MAP.

 

Can you give specifications for your propeller.  Also, have you measured the exhaust gas back pressure between the engine and turbo?  Finally, what turbo are you using?

Steve Boese
RV6A, 1986 13B NA, RD1A, EC2

 

 

  


From: Rotary motors in aircraft <flyrotary@lancaironline.net> on behalf of shipchief@aol.com shipchief@aol.com
Sent: Sunday, September 08, 2013 10:47 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] First Flight jitters
 
I've been slowly building my RV-8 with 13BT engine for about 14 years...!
On June 13th 2013 it received the coveted Airworthiness Certificate. That same day I detonated my engine due to the trailing spark plug holes being machined oversize in an attempt to improve the single spark plug power, should the leading plug ignition fail. This, and possibly advanced ignition, and possibly over-boost detonated my engine on it's first high power taxi test. That took about 2.5 seconds.
Now I've rebuilt the engine with new unmodified rotor housings, and it runs better than ever. I've re-marked the timing marks on the pulley, and reset the timing, though not to 4000 RPM yet. today I checked it. At 3000 RPM my hat and hearing protection blew off. 11 degrees BTDC, and 16" manifold pressure.
I've been taxiing around at modest RPM, it's great. I've consistently been idling at about 1600 RPM, (730 prop RPM) and sometimes as low as 1490, (680 Prop RPM) smoothly. That is slow enough to keep the brakes from getting too hot.
I've done run ups and brief bursts of power to 4200 Engine RPM, (1917 Prop RPM) which is about 32" manifold pressure, and seen 37" manifold pressure briefly. I know this is not enough power to take off, although I have done a Pre-take off to 50 MPH with this power before powering down with roll out to the end of the runway.  I suppose it would fly off and maybe clear the trees at this power. I've lifted the tail, and rocked the wings with the ailerons. It steers well and the brakes work.
The water level in the engine stays up between flights as does the oil, and the water temp today was consistent 163 F oil  about 173 with the highest observed 183F. I did about 4 pre-take off passes with taxi back, with excellent temperature control and throttle response.
A couple of oil fitting were tightened looking for an oil seep.
7.3 hours engine running time on the EM2, about 2 hours since the engine overhaul.
I don't think I'm at all ready to fly this thing. I'm missing something, so offer up some advice, I'm all ears!
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