What do you make of this? Cayley's coin.
It looks like he is conceiving of "lift" as acting perpendicular to the flight path, and conceiving of "drag" as acting purely horizontally.
That's kind of awkward, and not the convention we follow today...
Some websites describe the coin as representing the "four forces of powered flight", which it obviously does not.
In some of the Wrights' tables I seem to remember they followed a convention of "lift" acting purely vertically, and "drift" acting purely horizontally, in gliding flight.
We need to be careful to get in right when designing the new SSA logo depicting the L-D-W vector triangle as proposed in the thread "Debunking Glider Spoiler Turns Causing Spin Thinking" http://groups.google.com/forum/#!top...ng/svCmIstyZPU