You might wonder why different glide ratios, in the above diagram, all have identical angles. From the previous page we already know, that different ratios exposes different angles. Well, the explanation here is, that we are using a double logarithmic system. This is the only possible approach, if we want to embrace all varieties of flying objects in just one picture - from Cabbage White to B747.
Notice the glide ratio of the B747, it's about 15! Really this is not bad. Remember the glide ratio of the Schleicher Ka-4 glider from 1956? The glide ratio was 19! If a B747 loses all engines at an altitude of 11 kilometres, it will still be able to reach an airport within a radius of 165 km! If the captain is a former glider pilot, which some of them are!
Also you may notice that max glide ratio for the B747 is obtained through holding an airspeed of 130 m/s (290 mph and 468 Km/h).
A Fokker Friendship has almost the same glide ratio, but will maintain this ratio at a somewhat lower speed.
As a last minute note, I can add that a helicopter pilot once told me, that the max glide ratio of his chopper was around 3!! Therefore, when he flew over waters, he ascended so much that he could glide from the middle and back to solid grounds. Just in case!
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