Single-engine plane with the best range?

Your experience in the first example is due to the wing needing to fly
within a certain L/D for efficiency and your cooling drag... As your speed
goes up so does your cooling drag... As your speed goes down, the airfoil
L/D ratio deteriorates with increasing angle of attack...

A simple look at the manufacturers range curves for fast aircraft shows that
there a peak in the range plot at some point on the power curve... Since
the curve is a mountain (or valley, depending on how the ordinate and
abcissa are set up) there will be two points down from the peak, one at a
higher power setting and one at a lower power setting where the range is
exactly the same, and that is likely what happened to your high power / low
power example...

As far as fuel burn between a fast airplane and a slow one, that is apples
and oranges....

Now range for fast aircraft is strongly affected by the airfoil
characteristics... Slippery airfoils have a sharp rise in the drag as the
AOA is increased to compensate for lower airspeeds and lower lift... Fatter
airfoils have a lower rise in their drag with increasing AOA... My Apache is
a case in point... The lower the power setting the longer the range, mostly
because it's fat airfoil just loves high angles of attack...
- and because cooling drag , goes down rapidly with decreasing speed. and
vice versa -

Example at sea level:
75% = 940 miles
65% = 1040 miles
55% = 1130 miles
45% = 1220 miles

While I don't have a handbook for a Lancair IVP, or a Glasair III, I'm
willing to bet that there is a range peak with decreasing power between
roughly 68% and 63% and then it goes downhill from there because these
laminar flow wings have to fly inside the L/D bucket or the drag goes sky
high......
denny

"Stealth Pilot" wrote in message
bob my experience doesnt support that.

I fly a Wittman W8 tailwind with an O-200.

flying between Ceduna and Forrest via Nullabor Homestead is about 297
nautical miles.
I have made the flight with two settings.
-at reduced rpm (about 1800rpm) and about 70 knots. (in company with a
piper cub)
-at cruise rpm (2500 rpm) and 114 knots.
weight and aircraft trim was just about the same.

believe it or not the fuel consumed was the same.