----- Original Message -----

From: Al Gietzen

Sent: Wednesday, May 12, 2004 1:43 AM

To: Rotary motors in aircraft

Subject: [FlyRotary] Re: Runner Length

 

 

Al, focusing on the losses at these velocities and thinking that re-accelerating the column of air in the intake tract is a bad thing misses the point entirely.  That's like saying a supercharger will drop horsepower because it takes power from the engine to turn it.

Well; I don’t think it misses the point entirely.  I was just pointing out that accelerating the air uses energy, which is a negative in addition to other losses (reducing manifold pressure).  I didn’t mean to imply that you couldn’t get it back in a greater charge – it’s just not free.

 

 Al

Yes, accelerating the air in the intake runner takes energy but it is insignificant (virtually free).

 And,its the best investment an engine could make (assuming the intake system uses it to good 

advantage). To get an equal boost in VE any other way (Turbo or supercharger) takes more than an order 

of magnitude higher input of energy. 

Tracy