Playing around with the pitch phugoid

I find this an odd discussion since this is in reference to a dynamic mode that is related to the interaction between speed and pitching moment - it requires you not to make control inputs for many tens of seconds and the pitch, airspeed and altitude excursions that result are considerable. I don't know of any pilot or any airplane where this would happen without a deliberate effort to NOT fly the airplane - or if your elevator became disabled.

No one needs to think about controlling the phugoid - it is subordinated to simple pitch and airspeed control that happen on a far, far shorter timescale. The dominant dynamic mode there is short-period, but even that's not a big factor from a pilot control perspective.

9B

This discussion is such a mish-mash.
The phugoid came up in the discussion of the so-called benign spiral mode of exiting a cloud.
I once owned a flew a Grob 104 Speed Astir. It had a benign spiral configuration for exiting a cloud. It was full flaps, trim full aft, spoilers out, and hands and feet off of the controls. I experienced that situation and can tell you that the aircraft still had a phugoid behavior but it stayed within reasonable limits.
I now have an LS8. I practiced the benign spiral situation a couple of times and the phugoid got worse and worse until it was full stall to Vne. However, I neglected to pull the spoilers.
Last week I tried it again but pulled full spoilers. No phugoid! However, there would still be no way to control roll without proper instruments.
Now I have a full time, solid state, artificial horizon in an LX S80. No worries.

On Saturday, August 8, 2015 at 5:40:44 PM UTC-7, wrote:
This discussion is such a mish-mash.
The phugoid came up in the discussion of the so-called benign spiral mode of exiting a cloud.
I once owned a flew a Grob 104 Speed Astir. It had a benign spiral configuration for exiting a cloud. It was full flaps, trim full aft, spoilers out, and hands and feet off of the controls. I experienced that situation and can tell you that the aircraft still had a phugoid behavior but it stayed within reasonable limits.
I now have an LS8. I practiced the benign spiral situation a couple of times and the phugoid got worse and worse until it was full stall to Vne. However, I neglected to pull the spoilers.
Last week I tried it again but pulled full spoilers. No phugoid! However, there would still be no way to control roll without proper instruments.
Now I have a full time, solid state, artificial horizon in an LX S80. No worries.

Yes - good point. One way to damp the phugoid (If you don't want to touch the elevator - either because it's jammed or because you are trying a benign spiral) is to open the speed brakes at the bottom of the oscillation. I can attest that it works on a G103.

9B

On Saturday, August 8, 2015 at 10:40:35 PM UTC+3, Andy Blackburn wrote:
I find this an odd discussion since this is in reference to a dynamic mode that is related to the interaction between speed and pitching moment - it requires you not to make control inputs for many tens of seconds and the pitch, airspeed and altitude excursions that result are considerable. I don't know of any pilot or any airplane where this would happen without a deliberate effort to NOT fly the airplane - or if your elevator became disabled.

No one needs to think about controlling the phugoid - it is subordinated to simple pitch and airspeed control that happen on a far, far shorter timescale. The dominant dynamic mode there is short-period, but even that's not a big factor from a pilot control perspective.

Yes OF COURSE if you are controlling the pitch and therefore the speed then you will never see a phugoid. OF COURSE. But how do you control the pitch if you can't see the pitch or even changes in the pitch? What control input should you make? Normally you don't even think about this because it's so obvious and subconscious. But it DOES rely on outside visual references, and isn't going to work when you're in a cloud and don't have any.