On Mon, 25 Sep 2006 23:21:44 -0700, "Peter Duniho"
wrote:

"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

You might try the reverse order too. Look at best glide speed. In
calm air the best glide speed gives you the most distance per time
unit, but traveling either faster or slower will cause you to lose
altitude faster. Now compare best rate of climb; a speed either faster
or slower (Vx) will produce less climb versus time, so although the
best angle for clearing an object at a given distance you will be
going slower then the best rate of climb, but at a steeper angle. It's
that slower speed with less lift that gives you less altitude versus
time.




Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com