A better airplane analogy is that the main is the wing and the jib is a leading edge slat. A slat helps keep the air flow 'attached' (i.e., not stalled) at higher angles of attack. And sails run at very high angles of attack, as compared to wings.
Sail trim quiz question
- Thread starter Jackdaw
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To extend the analogy I might say that in a masthead boat with a large powerful Genoa it is the wing, with the main as a flap. On a more modern fractional rigged boat the powerful main is the wing, with the jib as a slat.
Having some but not much flying experience, could the main, with a large genoa, actually act as an elevator, also? But, I also understand the flap analogy. Is my thinking wrong?
I vote 'yes'. You can definitely steer a sailboat with the sails.
The limitation is in the sail's non rigid construction.
- Will (Dragonfly)
Kind of. But remember that an elevator doesn't provide any lift (in fact, it generally has negative lift), it's purely for pitch control. A better airplane analogy might be a three-surface airplane, such as a Piaggio Avanti, with two lifting surfaces and an angle of attack control (which is the elevator on an airplane and the rudder on a sailboat).
Am I correct in assuming that in this polar diagram, the black line is for a standard jib set-up and the red is for a flying headsail?
Correct. The VPP program is run for both sail combinations. Sometimes the presented graph will simplify and show one merged line of best VMG, other times that will show both lines so you can see the difference.