"RandyL" wrote in message
...
Here is something that I have always wondered about, but have yet to
hear a good explanation for. Vx is the best angle of climb speed for an
aircraft. Vy is the best rate of climb for an aircraft. I can't seem to
visualize why Vx is not the best rate of climb. To my feeble way of
thinking, Vx - the best climb angle - gets you to the highest altitude in
the shortest period of time, no? Why is that not the best rate of climb?

I think the other two posts cover the basic definition adequately. I'll
offer a mental view that sometimes helps me understand the relationship, and
which might clarify the difference a little bit mo

Vy is about the best *rate* of climb. That is, the most vertical distance
over a period of time. Vx is about the best *angle* of climb. That is, the
most vertical distance of a horizontal distance.

That much has been explained. It may also be helpful to know that Vy occurs
when you have the most excess power, while Vx occurs when you have the most
excess thrust. Power, being a rate-based measure (that is, work (that is,
force times distance) over a period of time), winds up contributing to the
best climb performance over a period of time. On the other hand, thrust,
being a measurement of the specific force acting on the airplane (and which
is independent of time), winds up contributing to the best climb performance
when time is ignored.

I admit that the above may only be helpful if you already think in terms of
physics. But perhaps it provides some additional insight into why there
even are two different V speeds and how they relate to the definitions of
them.

Pete