ORIGINAL: Nomad
Bingo Fuel would be the point at which an aircraft had a save amount of fuel left for return. I believe that is usually the amount that is precalculated plus 10% - but TheElf would be more up on that term. [8D]
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link to reference
Right - you generally need a 10% fuel reserve to have a good chance on getting back to base, since weather conditions might be adverse (a good strong headwind will ruin your day if you used 50% of your fuel on the way out). [X(]
It should be noted that the most common cause (or so i've recently read) of General Aviation (i.e. private pilots, generally flying propellor planes) crashes is running out of fuel - and they don't have to deal with battle damage, etc.
However, even if you LRCAP from 560 nautical miles/645 miles, the A6M2 model 21 is 1675 nautical miles - 10% (fuel reserve) = 1507.5 nautical miles, giving a range of 387.5 nmiles on station AT CRUISE SPEED. Cruise speed is 180 kts, max speed is 288 kts. You could theoretically have a loiter time of about 2 hours over target IF THERE WAS NO COMBAT.
If there was combat, your time over target is (180/288)^3 = 24.4% of that, or about 30 minutes.
The Japanese would try diverting to smaller airfields such as Buin, with mixed result. Many of the Zeros had no radios, and there are a lot of clouds in the Solomons so navigation could be a real problem... lots of planes got lost trying to find unfamiliar airfields and ditched (or crashed) as a result.
Notice, that in order to have 30 minutes - 2 hours over target, you need a mission time of 7 hours in transit + time over target (let's average it and say it is 2+.5/2 = 1.25 hours.)
If you want to get coverage over the target for 12 hours (sunrise to sunset) - your daitai of (say) 16 planes is only going to be able to have around 2 planes defending the target at any one time, which is not going to be terribly effective.*
All an attacker would have to do is send in a few fighters, dogfight for a bit, the defenders would have to Return to Base (RTB) - then the attackers could send in his bombers.
*EDIT: Note, that even in this scenario, the planes flying later in the day are going to be RTB in darkness - something that both sides were generally loathe to do.
ANOTHER EDIT:
NB. Bingo ( as I understand it from a poster here ), refers to going down to your last 10% of fuel. Flying 1,930 miles ( A6M2 maximum range ) at a cruising speed of 207 mph takes 9.32 hours. Therefore the 1 hour 56 minutes quoted above represents 20.74% of fuel. However, allowance HAS been made for fuel for the return flight. Therefore approx. 39.63% of fuel is used on the journey to the LRCAP area, 20.74% is used there, and the remaining 39.63% is used on the way home. "Bingo" therefore occurs near the home base.
10% fuel RESERVES, not 10% fuel... the reserves being the amount of fuel needed to return to base. So, simplistically, the pilot would plan for 45% fuel to get to station, 45% to return, 10% for the unexpected. Even with 10% "extra", pilots get extremely nervous flying beyond bingo, and if they are smart they won't do it.
