On Thursday, July 30, 2015 at 9:07:20 AM UTC-5, wrote:
Re what is the point of this thread?

I just find it fascinating that cloud flying without an artificial horizon IS routinely done in sailplanes by some pilots in some nations (see previous posts withing last 6 months to RAS), yet very little information is out there on how to stop the pitch phugoid.

My experience is that some sailplanes are dynamically unstable in pitch even when flown within the published CG limits. Of course I can't rule out an error in weighing or computations, but that's my experience.

This idea of "if your flying it right, a phugoid will never develop" doesn't hold water with me.

The idea of moving the stick forward when the airspeed is high, seems bizarre at first glance. Yet it works. See earlier posts for more. When the airspeed is high but no longer increasing, the glider is in a nearly level pitch attitude, and the excess airspeed will soon make the flight path curve upward strongly. The pilot needs to prevent that. By moving the stick forward.

After what I've seen firsthand in clear skies, I shudder to imagine any pilot ever venturing into clouds without an intimate knowledge of the dynamics of the pitch phugoid, and how to stop it. So you have an artificial horizon display. Do you want to bet your life that it will not fail? Then you are down to partial panel, and then what?

Besides, what's the point in just droning around the sky without understanding what is going on? Any pilot should be interested in these topics even if he never intends to come within ten miles of a cloud.

Those in the "I manipulate the stick to make the sailplane do what I want it to do so why do I need to understand anything about anything" camp need not engage in this topic...

S

Funny, people have been flying IMC using only a turn and bank and airspeed for a long time - without worrying about the pitch phugoid. As I said before - if you are actively flying the plane (actively controlling the speed via angle of attack, and the bank angle by controlling the turn rate by reference to the needle (while keeping the ball centered), your pitch phugoid is not a factor.

If you so mishandle the controls that you lose airspeed control (which is basically what you are describing) then you are probably going to end up in a spiral dive - a whole different ball game!

Are you saying you run into problems with a pitch phugoid "in clear skies"? How? You letting go of the controls? WHY?

And sure an AI makes IMC flight easier - and sure it can fail (which is why plane certified for IMC fligh have to have redundant gyros), but again that has little to do with the pitch phugoid! If you lose your AI (or T & B), you will most likely end up in a spiral dive.

Again: If you are flying it right - A PITCH PHUGOID WILL NEVER DEVELOP. If you let go of the controls, it probably will - but then by definition you are no longer flying the plane, are you?

IMHO, you are making a big mountain out of a small molehill...

Just fly the damn plane, for christ's sake!

Kirk