@Sunfish....
Originally Posted by
Sunfish
It's time of turnaround to range to crash site that seems to me to be important. If AE transmitted that she was in vicinity of Howland, how long did she spend looking for it before perhaps heading for New Britain? Half an hour? An hour? What fuel consumption while she was searching?
Quite so... The turnaround had to have occurred "after" Earhart spent an hour on a line search....
Firstly, We have Lockheed Report 487 which tells a pilot in a 20 mph headwind to increase speed by 4 mph, ie, 1 mph for each 5 mph of wind. Then there is a C.L. Johnson telegram telling Earhat that : "... if necessary, mixture can be leaned to 0.070
[a Cambridge Mixture Analyser setting] on last half of flight if exceptional head winds exist." So, Lockheed say "speed up" ...while Johnson says weaken the mixture, in effect "slow down".
My MS Excel plot has them holding a steady 155 mph speed at 10,000 feet after the
ONTARIO, until they descend towards the 1912 GMT call. They depart the Ontario with 651 USG and an AUW of 11,944 lbs and arrive at 1912 GMT with 339 USG after 8.6 Hours. I am using LR487 data for all Speed settings, ie: from expanded LR487 Page 30 data, I know what H.P setting is required for the speed according to the AUW and the Density Altitude flown. Therefore, my fuel usage figures are fully i.a.w. the LR487 Data.
We then have the 1912GMT call which was from 1,000 ft ALT and the "
...must be on you..." was the hopeful statement that they were 'there'. There then followed a 90 degree turn either to the North or South on the "157-337" Line of Position. If the search was for one hour , that means four fifteen minute "legs" up or down that LoP which at 150 mph G/S means a leg of 37.5 miles to a 180 degree turnaround back to the original trackline, cross the trackline and do another leg of 37.5 miles. The two legs therefore covered 75.0 miles. The total area of eyeball scanning possible from 1000' would be an area bounded by a racetrack line, 152.4 miles long and 77.4 miles wide. Nothing seen, even though the
ITASCA was emitting black smoke. By 2014GMT they were back on the original trackline having expended 36 USG of fuel by my reckoning,
Something has to be done now and that "thing" is that the previously thought out Contingency Plan is invoked and they turn back for The Gilberts. They have 303 USG remaining. The Electra AUW is 9,854 lbs.