Not to flog anyone's nag, dead or otherwise, but in response and as to room for doubt hereabouts -
I didn't say I had 'new information', just 'fresh consideration' -
One can 'do the math' in bookend cases:
Bookend ONE:
Using a fuel burn rate reported in a February 13, 1937 wire by "Putnam to De Sibour, London" - 310 pounds per hour (around 6.02 pounds per gallon at 59 degrees F): 310/6.02 = 51.495 gallons / hour - which is close to the "51.6" GPH and "52 GPH" as offered by Neff Jacobs (among other details) per below quoted posts:
...Having spent 40 years in engineering I will observe items become a commercial success or failure for more reasons than working well or not. Case in point Kelly Johnson measured significant improvement in fuel economy using the Cambridge Meter. It never seemed to catch on. Was that because Earhart didn't make it, or because the filters seemed to plug a lot, or because according to an article in a Darwin paper Noonan reported Earhart habitually burned 52 gallons per hour or because it used a leaner burn than Pratt and Whitney recommended? I strongly suspect a glittering endorsement form a successful Earhart could well have made the Cambridge Meter a must have item in all airplanes.
...
Neff
And -
I dug in my notes and found a quote from Sound of Wings, no page number. A Wire dated Feb 13 , 1937 ,Putnam to De Sibour , London , " Fuel consumption normal cruising speed per hour by weight 310 lb." 310/6=51.6 GPH These notes are yellow so from way back. Context justifying heavy fuel loads over British Territory. Max cruse for the engines would be 64 gph so it is not simply a claim for all it could burn.
Still looking for Darwin news papers.
Neff
Given that 1100 gallons were aboard at take-off in Lae per Chater, the Putnam/Noonan numbers yield roughly (splitting the difference between my more conservative 51.495 GPH and Noonan's least conservative 52 GPH = 51.7475 GPH) 21.257 hours of flight.
Bookend TWO:
Considering briefly Lockheed 487 Report by Kelly Johnson and The Kelly Johnson Telegrams per your comment upstring -
It depends on altitude, weather conditions (headwinds or tailwinds), throttle and mixture settings, engine performance, etc.
Yes. If Earhart followed Kelly Johnson's recommendations (and there's no way to know whether she did) she reached the LOP with about 190 gallons of gas left or about 5 hour's flying time at 38 gph - but that was at 10,000 feet pulling 24 inches manifold pressure at 1,600 RPM which delivered a true airspeed of 130 kts.
At last report, Earhart was flying at 1,000 feet presumably to get below he scattered cloud deck to look for Howland. If she wanted to keep her speed up at the low altitude he would have to bump up her power setting and therefore her fuel consumption. If she wanted to minimize her fuel consumption she would have to accept a lower airspeed...
Means something of around 38 GPH at best (at the end of all that fuel burn-off at the point of the LOP), or 26 hours out of 1100 gallons (roughly five hours remaining upon reaching the LOP) - which neither of us is likely to believe since as you point out she was not able to have such an optimum condition throughout the flight and because there are many unknowns, because as you say -
...What did she do? How far did she run north on the LOP before turning around and running south? Did she climb or did she stay low? How much power was she carrying. How fast was she going? What was her fuel burn? Nobody knows.
In sum we have two 'witnesses' (Noonan and Putnam) giving nearly identical 'reports' - if we dare trust that the wire and article written of exist (I'm going strictly by Jacobs' post at moment, having not seen that material - but he does cite notes in at least one case taken from the source) - of close to 52 gallons per hour, or roughly 21 and one quarter hour's worth of flying as a 'habit', AND we have the optimum Kelly Johnson case -
Split the middle if one will, etc. - that may be reasonable if we can believe that Johnson's pleas were sinking into Earhart's behavior, but we're stuck guessing.
As to running 'slower' to 'save fuel' - in increases endurance (time in the air), yes - but not range. Long explains that phenomenon well: if one is stuck trying to cover 'ground' (or open sea) to find a place, one is stuck using higher speeds to gain more ground for fuel burned. Johnson's curves show this if studied.
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So what is 'new'? A realization that at best (for the Niku hypothesis) 'we don't know' BUT IF Earhart were somehow on the LOP remarkably far south such as to not find even Baker by flying north (how far must one stand off to miss seeing that island at 1000' and skies no more than 3/10's if we can believe the area was generally as clear as Itasca reported?), and then stumble upon Gardner off to the west by a few miles of the extended LOP, she MIGHT have had 2 or 3 hours of fuel aboard.
My concern is that this is fairly optimistic - but 'nobody knows'.
My other concern is that at 52 GPH +/-, thunk and dunk comes eerily close to her 'last known call' ("we are on the line..."). When I consider the reports of her fuel burn habit (and that Johnson may have realized the problem and had been trying to get her attention, much as did Hooven in other matters) and the simplicity of it, I do not see crashed and sank as so 'irrational', even in today's light - in part because 'nobody knows'.
So there's nothing 'new' here - we've known these 'numbers' for years. Hence 'fresh consideration' lends room for huge doubt: I simply disagree that Long's notion has been rendered irrelevant.
Yes many things have been studied by TIGHAR over the years - but of even most recent study now are things like what role the island store may have played in supplying certain things to the seven site (as found by Betchart passengers under Tom King's supervision), that the 'camp zero' idea is an apparent no-go, and that we still lack airplane-defining hardware (I do look forward to TIGHAR's technical response to come on 22V1 (sorry, I've tired of keying the dashes in...)).
So, damn Putnam and Noonan for putting out that nagging commentary about 52 GPH anyway (26 GPH per engine), it creates a hellish outlier for us. It doesn't help that
perusing the net for R1340 fuel burn rates turns up that it is not unusual for the AT-6 (similar engine - same displacement and HP as on Earhart's plane, but single engine of course) to burn around 32 GPH in cruise - which would equate to a whopping 64 GPH on the Electra ("x 2") - the ridiculously high 'max rate', BTW, that we would not expect.
So the freshest consideration is that 'nobody knows', but arrival at Gardner with enough juice to transmit for 5 days is no shoo-in. Fresh consideration reveals that arrival at Gardner would depend very much on a very serendipitous alignment of what some might consider to be a too-long string of improbable things: fuel burn rates closer to Johnson's recommendations than not against reports of the time - split the difference if you will; arrival way far south on the LOP - which given the offset of that line being NNW - SSE means more 'ground' covered to reach it (which in the allotted time means more speed which means more fuel burned), thence missing the moon and sun for 'shots' in what reasonably were around 3/10th's sky cover conditions - AND being so far south so as to miss Baker at the very least on the north-bound leg.
None of which is to say "no way", Ric. It is simply to note that there remain rational reasons among many reasonable people to differ, that's all. And thanks, I realize you didn't accuse me of dishonesty or a lack of intelligence. Hats off for your efforts to turn up new things more lately than most others (no, I have zero confidence in the dust covers of whatzit island); and this isn't a 'pitch' for the 'other possibility(ies)' - it is merely to point out that others still 'hold water' (lots of it - that is a problem: the Pacific does occupy a huge basin).
Sorry for using so much space, but I hope something has been said.
All the best -