Long Range Power Settings (Get 15-25% Better Fuel Mileage)
A very wise and experienced Beechcraft Owner & Beech Lister, aka
Old
Bob, has suggested
that flight at best L/D airspeed (or Best Glide in your POH) times a factor of
between 1.1 and 1.2 will yield nearly the optimum in fuel mileage efficiency.
I have found Old Bob's guidance to be true in my
B55. Here are some examples of power settings that I have used for maximum
range/economy NM/gal in my B55:
Usually 8,000' to 12.000'
17" to 19" MP
2100 RPM
7.5 to 8.5 gallons/hour per
engine
Usually in the range of 128 - 138 KIAS
Calculated TAS is usually 150
- 162 KTAS
Here is a calculation from
Dr. Dave Rogers to
help you calculate (L/D)max for your particular weight:
"For the operational weight and the speed for L/Dmax varies
as the square root of the weight ratio, i.e.,
V2(L/D)max = V1(L/D)max*sqrt(W2/W1)"
NEWS FLASH: Recent 700nm Trip
at 9.3 gph/side, 2100 RPM, 19" MP (Full Throttle), 12,000' and OAT 11C I
achieved 172 KTAS!
NEWS FLASH: Recent 700nm Trip
at 10.3 gph/side, 2250 RPM, 19" MP (Full Throttle), 12,000' and OAT of -10C I
achieved 182 KTAS!
NEWS FLASH: Recent
800nm Trip
at 9.5 gph/side, 2350 RPM, 142KIAS, 30.29" Altimeter, 17" MP (Full Throttle), 15,000' and OAT of -12C I
achieved 178 KTAS!
NEWS FLASH: Recent
800nm Trip
at 10.9 gph/side, 2300 RPM, 159KIAS, 30.17" Altimeter, 21" MP (Full Throttle), 10,000' and OAT of
4C I
achieved 186 KTAS!
Power Settings Video of
~180KTAS @ 21GPH
Power Settings Video of
~168KTAS @ 18.5GPH
N2023W DTO-ATW 30 November 2021
@21 and 22GPH Fuel Flow
N2023W ATW-DTO 18 December 2022
@20.6GPH Fuel Flow
Gee Mike, why do you fly so high? Aren't you
burning up a lot more gas to get up there? Thought you'd never ask. Intuitively
it always seemed to make sense for me to fly high to get a higher TAS at a lower
fuel burn, excepting of course when facing mega headwinds up high. Well, here is
a chart created by Beech Lister and fellow Baron driver, Derek D, that shows you
actually SAVE fuel on trips of over 250nm.
You can see why I like the 10,000' to 12,000'
range for my trips of over 500nm. Thanks for the effort on the chart Derek!
Now, while you're in your climb, be sure to
Lean to a Target EGT in the range of 1250F to 1300F!
Here is a LOP Climb scenario that B58 Baron
driver Larry O. uses. It looks like it could be worth 3 gallons
For you Bonanza drivers, here are some drag
curves to consider when seeking maximum range/efficiency.
Here is a P-Baron L/D Curve (the normally
aspirated versions may be similar with a slight shift to the left - don't quote
me on that).
Lindbergh's Fuel Planning Chart
NY to Paris (courtesy Bill Compton)
Per
Bill: "Here is Lindbergh's cruise control plan for NY City to Paris,
1927. It was put together by Charles and Donald A Hall, the engineer who
designedSpirit of St Louis.
The "Ideal speed" lines for RPM and IAS represent Vldmax, which
decreases as the huge fuel (450g) load is consumed. But it shows the
intent to fly the "Practical speed" lines, initially more AoA than
L/Dmax (less IAS than Vldmax), catching up at mid flight, then less AoA
at the lower weights to follow (meaning more IAS) at a small fuel cost
at low weights.
Why
would he start w an AoA less than L/Dmax? My guess is that his engine
could not put out that much power without running rich, so he initially
flew on the back side of L/Dmax without taking a big hit on TAS. Second
half of flight, throwing in more IAS than Vldmax for more TAS at minimal
added fuel cost.
There's
a lot more there as well. It's like a puzzle slowly yielding even more
strategies. He landed with 85 gallons on board. Then his charts and logs
were stolen and never recovered, a terrible loss to aviation history.
This
chart and others were found in 1999, in a forgotten trunk in Donald
Hall's grandson's garage. Google at NACA technical note No. 257. Done
with drafting tools and a slide rule."
Here are pics of Kevin O.'s IO-550 powered
Debonair making 175KTAS at 14,500' burning 11.8 GPH!
That's the kind of efficiency I'm talkin'
about! Go on up there and get some thin air with that big boy engine
Here is a climb chart and narrative created by
Ward A. for the NA-A36.
The conditions are climb at full power at 120KIAS Cruise at 75% LOP, or full
throttle LOP. Descend at 165KIAS, -500 FPM at what-ever power it take
(constantly adjusting). Above 12k ft, we descent at WOT, and 500fpm at whatever
speed we can get (less than 165KIAS).
As you can see, we're not doing anything unnatural to save fuel. All this is
in comparison to a flight at Sea Level. Note that up to 7k or so, the climb is
free. Above 7k, we save fuel, because we are flying at a slower IAS (read more
efficient) than we are at sea level.
Ward
PS - In a TN - you get more or less free climb to all altitudes. I don't
hesitate to climb to 17.5k, even on a short 200nm flight.
Check out the
EGT Leaning Presentation
from the good folks at Advanced Pilot Seminars.This can also help you determine what fuel flow is best to use at high
altitude or high DA situations.
See
Pics of Actual in-flight Power Settings at 10,000'/8.2 gph per side/12C Yielding 162KTAS
HERE
(Click thru 4 pics)
Here are pics of my Exhaust stacks after a 5 hour LOP flight from KATW to KDTO