Equation question from Reichmann X-C Soaring

I am working with a fourth printing (1988) and the equation presented
for Optimum Average Cruise Speed does not make sense. It is equation
VI in the book, but it gives a very slow speed to fly compared to the
graphical approach of just finding the tangent to the line.

Plugging in zero for the sink rate in equation V gives the same result
as plotting the tangent on the polar, I am not sure what equation VI
is finding.

Any one have some insight?

Thanks,

Tim

On Feb 19, 10:36 am, Tim Taylor wrote:
I am working with a fourth printing (1988) and the equation presented
for Optimum Average Cruise Speed does not make sense. It is equation
VI in the book, but it gives a very slow speed to fly compared to the
graphical approach of just finding the tangent to the line.

That equation gives what might be called the average "travel" speed of
a leg (Reichmann calls it a "cruise" speed), which includes the time
spent thermalling - it is not a "speed to fly". Jack

On Feb 21, 8:09 pm, Jack Glendening wrote:
On Feb 19, 10:36 am, Tim Taylor wrote:

I am working with a fourth printing (1988) and the equation presented
for Optimum Average Cruise Speed does not make sense. It is equation
VI in the book, but it gives a very slow speed to fly compared to the
graphical approach of just finding the tangent to the line.

That equation gives what might be called the average "travel" speed of
a leg (Reichmann calls it a "cruise" speed), which includes the time
spent thermalling - it is not a "speed to fly". Jack

Right - Be a bit careful, as the English translation has many
unfortunate names for the terms in these equations...

On Feb 21, 6:33 pm, wrote:
On Feb 21, 8:09 pm, Jack Glendening wrote:

On Feb 19, 10:36 am, Tim Taylor wrote:

I am working with a fourth printing (1988) and the equation presented
for Optimum Average Cruise Speed does not make sense. It is equation
VI in the book, but it gives a very slow speed to fly compared to the
graphical approach of just finding the tangent to the line.

That equation gives what might be called the average "travel" speed of
a leg (Reichmann calls it a "cruise" speed), which includes the time
spent thermalling - it is not a "speed to fly". Jack

Right - Be a bit careful, as the English translation has many
unfortunate names for the terms in these equations...

Jack and Dave,

Thanks, I finally realized it meant "Average" speed, then found it
written that way in "Competing in Gliders".

Thanks,

Tim