Bill,

 

Righto.  Best glide = max endurance = minimum power for sustained level flight.  For a 320/360, best glide is about 105 KIAS - a more accurate best glide can be found with a calibrated angle of attack indication for the flying weight and configuration.

 

It doesn't take much power.

 

But, if'n your engine quits, it doesn't much make no never-you-mind.

 

There are three configurations of interest for airplanes with non-feathering constant speed props controlled by oil pressure.

 

1. Engine seized, prop flat (no pressure to keep some pitch in it).  What is the best glide descent rate.  Probably some medium amount of drag.

 

2. Engine rotating, cruise pitch (forgot to pull the prop to coarse pitch).  What is the best glide descent rate.  Probably horrible flat plat drag.

 

3. Engine rotating, coarse pitch held by oil pressure. What is the best glide descent rate.  Least drag possible.  Note that coarse pitch drag reduction is within a few percentage points of a feathered prop. 

 

The point being that a slicker-than-snot airplane's performance is greatly affected by any drag addition.  This is unlike riveted, wing struted and welded down gear drag queens where the airframe drag is so great that any additional doesn't change performance by much.  Check your prop manual for the pitch range limits (flat to coarse).

 

Finally, thanks to Walter at GAMI,

 

%HP = 100-((max RPM/100-RPM)*2.5+(Max MP-MP)*3.5)

 

See what the RPM and MAP are at your best glide speed for a %HP figure.

 

Grayhawk

 

 

 

 

How many HP are required to keep a Lancair in the air? The wing loading is
high so speed needs to be kept up but the airframes are very clean. A little
bit of extra power may make a big difference in perceived results.