Meaning to be coordinated

[Stache]

In a discussion about aerodynamics one of the questions that I was asked, and subsequently been tasked to answer, is "What does it mean to be coordinated?" What do we really mean when we say airplanes are coordinated in a turn?

Stache

 

[MikeHalloran]

It means that control surface movements are continuously coordinated during a change of heading, so that the local apparent gravity vector stays vertical in aircraft coordinates. I.e. the vector component of real gravity that is not vertical in aircraft coordinates is balanced by centrifugal force. Or is it centripetal?

No matter. In layman's terms, it means nobody's drink gets spilled.





Mike Halloran
NOT speaking for
DeAngelo Marine Exhaust Inc.
Ft. Lauderdale, FL, USA

 

[aviat]

Very basically it means keeping your ball in turn and slip centered. Google airplane slipping and skidding turns.

 

[CESSNA1]

STACHE: A coordinated turn is when the airplane turns in a perfect circle. In an uncordinated turn the down aerilon has more drag than the up aerilon and the you get "adverse aerilon yaw". In this case the nose of the airplane yaws to the outside of the turn and the airplane slips and/or skids in the turn. Also drinks spill and fuel sloshes in the tanks and may uncover the outlet line. In a coordinated turn the ball is centered and even though the airplane is banked the drinks and fuel are still level in their containers. That is because the accleration vector is directed into the floor of the airplane and is directly opposite the lift vector. The turn is "coordinated" with the use of the rudder in the turn.

Regards
Dave

 

[aerodog]

Old time pilots have told me that in the early days of flying instruments, they would fly with a cat in their lap.

The cat would lay there peacefully asleep. If the airplane would start to skid (too much rudder, not enough aileron) or slip (too much aileron, not enough rudder) both examples of uncoordinated turns, the cat's claws would dig into the pilot's pants leg. It would be an early indication that something was amiss.

Reliable autopilots eventually grounded the cats.