B737NG_Pilot

Switching from conventional aircraft to an aircraft with FBW, What's the difference between pitch rate at low speed vs G demand at high speed. How does it make a difference to the pilot ?

vilas

In both whether G or or pitch rate the stick movement only commands a rate or G which the FCC achieves by moving the elevators to the required amount. Since at any speeds certain movement of stick always commands the same rate or G the pilot's movement of the stick also remain same. Not more at low speed or less at high speed.

B737NG_Pilot

Hi Vilas... thank you for your response. Your responses in other threads have been very helpful at times in understating the A320 systems. What I am trying to understand, is why use two different terms "Pitch Rate" & "G- Load". Is the movement of the elevator more or less for the same movement of side stick in "G Load" when compared to "Pitch Rate"?

320busboy

Best I understand, in the laws for take off and flare it uses pitch rate so it’s essentially conventional. Other times when in normal law it uses g load as that’s the critical parameter. Should be hard to over g the aircraft in take off or flare.

fab777

Rotation and flare use direct elevator deflection law. In flight, normal law uses a blend between G demand and pitch rate, depending on airspeed and mach, in order to give a constant feeling to the pilot. With a G only law, the aircraft would be too sensitive in pitch at low speeds, and same thing at high speed with pitch rate only.

Hope I am being clear...

PilotLZ

Pitch rate demand is used in the rotation law of the Neo. The idea behind it is a homogeneous rotation, regardless of CoG. On the CEO, rotation is flown with a direct stick-to-elevator relationship and transition to normal law (load factor demand) in pitch happens in the 5 seconds following lift-off.