Gerry,

I agree with everything you said.

Would you agree that augmenting an airplane's weight undoubtedly
increases its drag? Doesn't matter if the airplane is powered or not.

Now, apply that to an airplane in a steady climb at full power and
best L/D speed and another one that's gliding at best L/D. Both
airplanes are identical so ideally, they would be flying at the same
speed since I don't think best L/D speed changes with power settings.
I hope we can agree that both airplanes are operating at their minimum
drag points, points of least thrust required. This means that in the
case of the airplane climbing, its climb angle is maximized. In the
case of one gliding, its descent angle is minimized.

I hope you're still in agreement.

Next, double both airplanes' weights, and fly them faster by 41%
(sqrt(2)) so that they are still operating at their best L/D angle of
attack.

Would you agree that in both cases, both the drag and power required
increased?

To me, I immediately relate the increase in drag as a decrease in
climb angle (for the powered airplane) and an increase in descent
angle (for the gliding airplane). Likewise, the increase in power
required means a decrease in climb rate (for the powered airplane) and
an increase in sink rate (for the gliding airplane).

Final conditions: For the powered plane that's ascending, as you've
said, the airspeed will be higher, maximum climb angle SHALLOWER,
climb rate lessened, ground speed increased.

For the gliding airplane, the airspeed will be higher, glide angle
UNCHANGED, sink rate higher, ground speed higher.

I've capitalized the effects I don't understand. In both cases, I
contend there was an increase in drag that should have affected both
airplanes' flight path angle to maintain equilibrium of forces.

Best regards,
Alex