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[Ric Gillespie]

Amelia had no incentive to burn extra fuel.  Amelia would certainly not want to risk burning into her 50 gallons of 100 octane additional reserve fuel she carried in her 102 gallon tank as she would want this for extra takeoff power from Howland. At Lae and at and again at Howland only 87 octane was available and was used for cruise flight. She would not be able to replenish the 100 octane until Hawaii.

I agree. She would certainly want to preserve as much of the 100 octane as possible for the Howland takeoff, but she also needed some of it for the Lae takeoff.
Balls-to-the-wall, her engines burned about 100 gph, so 50 gallons would give her half an hour at max power.  Theoretically that's 15 minutes for the Lae takeoff and climb to an altitude where she felt comfortable switching tanks, and ditto for Howland.

[Ric Gillespie]

I think these recommended figures give a maximum endurance (time based), rather than the maximum distance, although for the low to moderate headwinds here it makes little difference to the fuel economy for distance - so the point is moot.

The recommended figures deliver maximum efficiency.  You can get greater endurance (time aloft) by loafing along at very low power settings but you won't cover as much distance. Distance covered in either case depend on winds aloft. 


For high headwinds however - where the headwind is a significant portion of the airspeed, there is a case for a speed increase, as the ground speed increase may exceed the drag/power/fuel usage squared increase.

I don't understand how that would work.  If there is a power settings formula that delivers a ground speed increase greater than the drag penalty, why wouldn't that be the maximum range formula regardless of wind?

[Simon Ellwood]

I don't understand how that would work.  If there is a power settings formula that delivers a ground speed increase greater than the drag penalty, why wouldn't that be the maximum range formula regardless of wind?

Because we're talking about ground speeds, which at high headwinds are obviously substantially reduced from the airspeed - at some high value of headwind (around 62mph in this case), the increase in ground speed exceeds the (increase in fuel burn)^2.
These headwind values are very high, and this is purely hypothetical - I'm not trying to say Earhart would have seen these winds nor adjusted speed/power. If she had, then she'd have fallen long short of Howland !

But for an example, take a 75mph headwind:-   ground speed = 130-75 = 55mph.
Say we increase power so as to give 10% extra airspeed (x1.1) = 143mph at the expense of burning (1.1)^2 = 1.21 x the fuel.
The ground speed is now 143-75 = 68mph, which is 23.6% faster than 55mph, at the expense of only 21% extra fuel.

[Ric Gillespie]

I see your point.  Digging deeper, Lockheed Report 487 addresses this issue in some detail.
Page 2
"During the maximum range flight, the following considerations apply:
a. Variation of altitude from that specified by amounts
as much as 2000' (except in the heavy load condition) has very little effect on the range.
b. With headwinds or tails winds up to 20 mph, the best airspeed is wthin 5 mph of that shown on the flight procedure curve.
c. When the wind increases with altitude, the load condition, and power conditions should be carefully considered when choosing an altitude different than that shown on the curves. No strict rules can be given covering the optimum flight procedure with varying wind gradients with altitude.
d. Increase the power output when climbing from one altitude to another. Climb at an indicated speed of 120
to 130 mph."

Figure II on Page 8 provides performance curves.. Higher airspeeds are recommended in headwind conditions.

To what degree Earhart understood or followed these recommendations is another question.  We know she did not use 30° of flap for the heavy Lae takeoff as recommended on Page 2 of Report 487.

[Scott C. Mitchell]

Would an aviatrix in those days keep logs of route changes, fuel consumption, weather, etc.? / Scott #3292

[Ric Gillespie]

Would an aviatrix in those days keep logs of route changes, fuel consumption, weather, etc.? / Scott #3292

Earhart habitually kept notes of such things during a flight and probably did during this trip.

[Scott C. Mitchell]

Thanks for the background information on AE's routine of keeping notes.  Reminds me of the lost ships' logs of the British ships Erebus and Terror, trapped in the ice in the Northwest Passage with the loss of all crew.  There was lore among the Inuit in the vicinity that the ships's books and papers, and presumably the ships' logs, were stored in a cairn before the crew abandoned the ships for their doomed march south.  Just a few notes from either EA or those ships could validate much of what we can only speculate on now.  The officers did leave a standard one-page ships report that was recovered, but it raised more questions than it answered, which may be likened to AE's sparse radio transmissions. / Scott #3292