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Dava Sobel in her book "Longitude" relates the story of an British fleet of 4 warships that ran aground in Sicily this way.
Sure, but in ye good old days of WW2 a man called a navigator would still use a chronometer and sextant to workout longitude and latitude. If he knew his speed in knots as well as heading he could conveniently estimate his change in position, between fixes, in terms of degrees, minutes and seconds. The knot and nautical mile is superior for this. In many cases fixes were via radio navigation beacons.
You see plexiglass bulbs in the dorsal position of many bombers to take a celestial reading, the end of the glass house in the Lancaster I assume but often evident in flying boats.
Juggling various units can be annoying at best, or dangerous at worst, like the mars probe mission a few years ago.
England should adopt the metric system for football (soccer). While the pesky Germans have only 11m to score a penalty the poor English have to do it in 36ft.
So thats why Germany keep beating England in shoot outs. They cheat by spotting the ball closer nothing to do with England being rubbish at penalties
Many/most missions were flown at night which inevitably posed different problems to those faced by his US colleagues. Not least he could rarely, if ever, see the ground but he could see the stars and other heavenly bodies. 10/10 cloud prevented US navigators from seeing the ground, sometimes with disastrous results.
Not as easy as you may think. If you have any high clouds a sextant is all but useless. I knew navigators who never used them. Dead reckoning worked well and although the ground could obscured one could hope for "breaks" so visual references could be made. I've flown at night "over the top" and you could still pick up a lot of visual references through patchy clouds. Although the same could be said for celestial navigation, you were still in the blind when calculating you're exact location when over a target. Additionally attaining a celestial fix required the aircraft to be straight and level. I believe that the USAAF mainly used celestial navigation as a crosscheck to DR (when possible) and when traveling over long water routes.
In the U.S.A. we've had car speedometers with both mph and km/hr for more than 35 years. We know how fast we're going in either unit and see no reason to change the units in our own country. If foreign people come here and rent a car, the speedometer is clearly marked in both units. There is NO excuse for speeding and saying you didn't know. The cops don't buy it.
In Saudi Arabia the marked speed limit is per person so a Merc with 4 teenagers in is unrestricted, anyways, thats the only explanation we could figure out for how they drive.Somewhere in there I realized I was reading the larger font numbers on the outside of the speedometer dial, as I was used to. However on this Canadian car the outside numbers were KM/H, and the smaller inside numbers were MPH. DOH! When I thought I was at 65 MPH I was really at 65 KM/H.
T!
Pilot manuals for F4U-1, Avengers and SBD-3 all give ranges in Nautical miles and give aircraft restrictions (dive speeds, lowering landing gear, flaps etc) and landing speeds in knots. One would assume that the airspeed indicator was knots (photos are too small to tell) to prevent mental gymnastics in the cockpit. When or even if there was a change over I don't know. US Navy may have used Knots in the 30s if not before.
Manual for the TBD-1 (Douglas Devastator) uses knots.