icaruss

RNAV approaches, including those with LPV minimums are non-precision. RNAV approaches with Ground based augmentation system (LAAS) also known as GLS approaches are the only satellite based precision approaches.

Steve was only expressing an opinion/question about something via a forum. No reason to feel dissapointed or baffled about it.

Jaime, I understood what you we're trying to say. I'm also used to being critized by FTEs during test flights . That being said, I agree it looks a little unprofessional, but there nothing written as to how old the yoke during take (that's my assumption for this case especifically). Would I say something to my copilot flying like that, absolutely, specially if I'm instructing.

Make sure you understand the FBW control laws, well enough, that you'll know what to look for when you start degrading modes.

The only practical application is really the relation between pilot workload and the longitudinal dynamic stability of the aircraft. A good example is airspeed maintenance. If the pilot has to constantly make longitudinal inputs to maintain an airspeed (high workload), then the reason could a problem in the longitudinal dynamic characteristics of the aircraft.

After the excitation there is not input made to the flight controls. Controls-fixed just mean that we keep them fixed (without making any inputs). There is some variance in the results, and they are both valid.

You'll be surprised how little reversible flight controls (like the one on the cessna) move when doing controls-free testing, remember that all controls are trimmed before the phugoid is excited. In my experience, the results for both controls-free and controls-fixed are very similar, and a lot of it depends on the type of flight controls system. For example, there are flight controls that move to automatically trim for an airspeed. In such systems, If you do controls-fixed while the airspeed changes during the phugoid, you'd be fighting the stick. Irreversible flight controls (such as the one on 777), are a little trickier to test because of all the augmentation. You're really testing the FCC when all the system are working. A perfect example is the stabilalizer trim. Not knowing the 777 flight control laws, my guess is that the stabilizer is triming as the airspeed changes. In that case, you're really looking at the "pseudo" longitudinal dynamic stability of the airplane, which is fine because the airplane was designed to be flown that way.

A pulse is a very defined term in flight testing, just wanted to clarify that. A phugoid can be flown controls-free or controls-fixed (following the excitation), as described in the flight test manuals. In fact, when I do flight test, I usually do both methods in case there's a difference in the response.

The FBW does affect the excitation (which is not really a pulse, that's something else). Not all phugoid tests are done hands off. Not sure what you mean by "designed to fly like a non-FBW aircraft."

Aircrafs are mainly tested in the same way as they are flown. My assumption is that Boeing did the majority of the tests with all the augmentation on. However, tests are also done with degraded systems to ensure the aircraft can be flown safely back to an airport.

This was a controls free method, meaning that the controls were free in the longitudinal axis following the excitation of the phugoid (also called Long-Term Response). The roll attitude can be maintained at zero, as long as the longitudinal axis is not disturbed (hard to do). Like you said, clock is then started to record peak altitudes, airpeeds, and attitudes, etc. The graph above shows a positive and convergent response, which is what you want in a fixed wing aircraft. In an aircraft such as the 777, you're really observing the response of the augmentation (FBW, FCC, etc) when trying to excite the phugoid. Sometimes during initial testing, these augmentations are turned off to a degree, to observe the "true response" of the aircraft. In some cases, that is not even possible because loss of control would happen in seconds. Flight test is also done in simulators. When a response of the real aircraft is known, variables in the simulators are adjusted to replicate the real thing (not sure if this was done by PMDG).

The Flight Test Manuals, commonly known as FTMs, are the bible for Naval Flight Test. The FTM 108 is used for fixed wing performance flight testing. Being a Naval Test Pilot school grad myself, these manuals require a lot of study, but are paramount when conducting DT (developmental testing). Not sure how deep the PMDG software was developed in order to recreate the true 777's flying characteristics, but the video was very interesting.

In flight test, the aircraft responses are usually described as positive, negavite, neutral, divergent or convergent for dynamic stability testing. Nice video by the way.