Túrin took a seat without heed, for he was wayworn, and filled with thought; and by ill-luck he set himself at a board among the elders of the realm, and in that place where Saeros was accustomed to sit.

So, in the helicopteron, as the helix is at the same time a sustaining plane, it should be likened to a surface moving horizontally, and in which, consequenty, the resistance to motion will be to the lifting power as the sinus is to the cosinus of the angle formed by such plane with the horizon.

How say you, my lusty compeers; shall we permit a hinderlin to sit at board with us, and brand us with the name of cowards?

You're not the first man who has made such a mistake, and found he was barking up the wrong tree.