Mailing List lml@lancaironline.net Message #35963
From: Gary Casey <glcasey@adelphia.net>
Sender: <marv@lancaironline.net>
Subject: Climb speed, engine reliability, crankcase vacuum and Lancair certification
Date: Tue, 16 May 2006 23:22:09 -0400
To: <lml@lancaironline.net>
A few comments and observations on several subjects:

1.  Climb speed - slow is probably better, but climbing at Vx makes pushing the nose down after an engine stoppage critical - I've elected to climb at Vy as soon as practical.

2.  Engine reliability - my comment about making sure the engine will run for a minute after takeoff was more directed toward routine operation, not the first flight.  The normal runup routine doesn't really address that issue.  Certainly the fact that it ran the last time is a good indication, but I don't know of a way to guarantee it will do it again.  Maybe a rhetorical question.

3.  Crankcase vacuum - I don't think it is worth the hp loss to put a venturi in the exhaust just to pull a slight vacuum in the crankcase, and there is no intake manifold vacuum available most of the time.  I do think it is a good idea to install a standard automotive PCV system in an aircraft engine.  If the engine is aggressively leaned on the ground that, in combination with the PCV system will reduce CO and HC emissions to probably less than half what they would be otherwise.  It would also pull fresh air into the crankcase during the idle before shutdown, potentially reducing corrosion between flights.  Emissions on the ground are where people live and perhaps it is time to consider this.

4.  Lancair certification - I'm certainly not the expert or even an insider here, but the information I have is that Lancair early on decided to take the FAA option of certifying the plane as "spin resistant" rather than the traditional "spin recoverable".  That was a bit discouraging to me, building an ES as I am not in the position to copy that approach.  As I understand it the problem was in creating systems that met these new requirement with no industry experience to go on.  My observation is that as soon as we bolt on wings with (relatively) sharp leading edges we are trading stall performance for speed.  It's been a recognized tradeoff since the first Mooney or Comanche was built.

Gary Casey
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