A couple of replies:
Originally Posted by
AbsoluteFokker
Is there any reported data on prior legs' distance/duration/fuel uptake, to establish some sort of SOP for the crew?
Human psychology being what it is, advancing the throttle to "get through it" is common. Been there myself and dealt with "well under fuel minimums" after subsequent diversion.
i'll take a break from the plot for a while to reply to this by Absolute Fokker.
Researchers do not know much about fuel uplifts after a Long Distance flight but there is the one example and that was after the March 1937 SFO-Hawaii flight 2400 miles to Wheeler AFB up the valley from HNL.
The SFO Fuel load was 947 USG and at about the 14 Hour point of the 15:51 total for the flight, it was realised that they would arrive at Wheeler in the dark (they at one stage had a G/S of 180 mph), so the power was
reduced from cruise power to an IAS of 120 mph and Earhart wrote, "We are burning less than 20 gallons of gas at 10,000 feet" (Ref: Page 36/37 of "Last Flight" written from her notes). At that fourteen hour point the Lockheed published fuel usage for a Long Distance flight should have been 713 USG, leaving 234 USG. Now, "some people" say that the 20 USGPH she said she was using was "40 USGPH" because the fuel flow gauge was a twin needle instrument BUT this is denied by the fact that Earhart
reduced power from the normal cruise fuel usage of 38 USGPH at that stage of the flight, so how can a reduced power setting use more than 38 USG. ? Personally, from my workings with the low AUW's and the low power required it is possible to get the fuel flow down into the "Low 20's on an endurance flight". So slowing the Electra down presumably started the descent process, i.e: My opinion is that what Earhart was saying was that a power glide was started at that point and the power she had selected at 10,000 feet produced that Fuel Flow reading, that to me is the more likely scenario but it is in the book in B & W..... That opinion is confounded, however, because in the book Earhart says, "80 miles from MAKAPU (the beacon) Fred says start down"...... There were nearly two hours (before their arrival at Wheeler) ....at the aforesaid 14 hour point.....of a low power slow descent on the approach into OAHU which was by rounding Diamond Head passing HNL and heading up the valley for Wheeler. My workings show that with 458.3 square feet of wing area the Electra was a bit of a floater at low AUW's only needing low power to keep going.
Earhart told the assembled Press that she had "
over four hours of fuel left to search for OAHU if they had missed it".
They landed at Wheeler and the Civilian Fuel Contractor started putting fuel in. He was stopped by Paul Mantz who discovered contamination in the chamois leather fuel filling funnels they were using and the refueling was stopped. How much did they put in before it was stopped ? We don't know, but it could not be to the required load for HOWLAND which was 900 USG for the 1900 Statute Miles Hawaii-Howland because they needed more fuel.....
Next, it was decided to fly the Eectra to LUKE Field on Ford Island as the Army would sell them High Octane fuel there. Paul Mantz then flew his fiancee around OAHU sightseeing for about a half hour on the fuel that was in the Electra and landed at LUKE Field where the Army refuelled the Electra up to 900 USG by adding 590 USG. So when the Electra landed at LUKE, there must have been 310 USG in it after Mantz's fly-by using probably 40 USG at low level meaning 350 USG in the Electra on departing Wheeler Field and if the contractor added 50 USG at the most before he was stopped then the Electra landed at Wheeler after the Long Range flight from SFO with 300 USG which is about the "Over 4 Hours" that Earhart quoted that she had left of Low-level Fuel usage at say, 60 USGPH..
If that is the conclusion then it is obvious that the Electra used "less" fuel than the Lockheed figures which are 100 USGPH for 1 Hour, 60 USGPH for three hours, 51 USGPH for three hours, 42 USGPH for three hours, and 38 USGPH for the rest.
For
Harry of Heathrow:
Who says: "I suspect that they were so focused on range and endurance (which they could monitor) that the risks of course (which they had little precise info on by modern standards), came a bad second".
I guess any pilot who is given a wind forecast of 12-15 mph would be a bit disconcerted at finding a wind of 26.5 mph at 7 Hours into a LR Flight. Fuel assets would be of very high concern at that stage with easily over 11 1/2 more hours to run on the original FP.. Far from what was supposed to be an average G/S of 138 Mph my workings show an average of 130 mph at that 7 Hour point but it gets worse when they turn full on into the wind at NUKUMANU and between NUK and the U.S.S. ONTARIO (427 SM over 3.6 Hours) the average G/S drops to 119 mph.. Fuel would indeed be a major concern and could explain why Harry Balfour in LAE heard "On course for Howland at 12,000 feet" saving a little fuel by going higher....?
Back to the plot, still a long way to go.