In doing some searching for LDmax for the Lancair ES,
I read the statement that best economy would be the same as best glide.
That makes sense to me. Probably close enough for our purposes.
What say you?
I found my data. I think it may be
just a bit more complicated. Best glide will likely give you the lowest fuel
burn rate (gph); but since you’re going fewer miles in an hour; it’s
not the best mpg. My best glide speed is about 90 kts; but my best mpg is
about 130kts - quite flat from about 140 – 120 kts. The burn rate
was continuing to go down at 110 kts; which was as far as I took data.
So minimum trip cost is at max MPG; if
you consider your time as free. But my plane seems to have a ‘sweet’
spot at 5500-5700 rpm, and at 10,500 I can go about 170 KTAS at a tad over 10 gph,
so that’s what I do. I could slow to 130 Kts and burn a tad under
7.0 gph; but would I be happyJ?
Al
Mark
On Mon, Nov 1, 2010 at 5:53 PM, Al Gietzen <ALVentures@cox.net>
wrote:
Where does one find the "most efficient
operationg point" for a particular airframe? Is this the same
as LDmax?
Mark;
The
EM2 reads out MPG. Most efficient operation would be where you get the highest
MPG. So go fly at 100F, or so; lean of peak EGT and take some data of MPG and
speed. You’ll find a max MPG point that is slower than you’ll
typically want to fly. I think for my Velocity it was a fairly broad peak
around 125 (I don’t even remember now if that was MPH or Kts; because I
never fly there in level flight). We didn’t build sleek airplanes
with more powerful engines to go the speed of a Skyhawk – did we?
Al