VLD and max altitude

"Chris W" wrote in message
newsXj2e.4478$Tn.3559@lakeread06...
[...]
If you can't climb any higher, how could you have any excess power?

The key here is "greatest excess power". At the absolute altitude, your
excess power at Vy is 0. But at any other speed, the airplane actually
requires more power than is available; "excess" power is negative. 0 is
larger than any negative number, thus you are still at the "greatest excess
power".

[...]
I'm not sure there was specifically something I wanted to know (sort of
thinking out loud) except maybe what speed you should shoot for to get to
the max altitude. If you increase the AOA too much, and go too slow, you
won't reach the highest possible altitude. From what you are saying I
guess Vy is the speed you want to maintain, but as you said that changes
with altitude.

You should start at Vy, and gradually reduce your airspeed as you climb. As
a very rough guess, average Vx and Vy at sea level and aim for that at your
final altitude (so, it will help if you have at least a rough guess as to
the absolute ceiling of the airplane in question, so you know how to adjust
your airspeed as you climb). Vx and Vy don't actually change at the same
rate, so the final Vx and Vy that are the same isn't actually their sea
level average. But it's not far.

The question of what airspeed to fly at maximum altitude will be answered
when you reach maximum altitude. There is only one airspeed at maximum
altitude at which you'll stay at maximum altitude. Any other airspeed will
result in a descent.

So, one way you could do this is to start at Vy and climb. When the
airplane stops climbing, reduce your airspeed by a knot or so. If the
airplane starts climbing again, repeat the exercise each time it stops
climbing. Once reducing the airspeed after you've stopped climbing results
in a descent rather than a continuation of your climb, you've hit the
absolute ceiling of the airplane.

Note that all of the above is for real life situations. While I think MSFS
gets more crap for its flight model than it deserves, it's true that some
odd things sometimes happen near the boundary cases. I can't guarantee that
everything will work exactly as it does in real life.

Pete