Flying a high-wing plane like the Jabiru, why does the nose pitch down at the point of stall? The obvious answer is there is a loss of lift and the heavy nose of the aircraft makes the whole plane pitch down. But aerodynamically it doesn't make sense to me. Let me explain:Given the lift moment arm is behind the CoG, any loss of lift due to a stall would cause a pitch up tendency wouldn't it? In fact, in a high-wing aircraft the increase in drag at the stall would also create a pitch up tendency. I presume all other forces (thrust, weight and tailplane) acting around the CoG remain the same at the point of stall (the tailplane is designed not to stall so the elevators remain effective when the wing stalls).
Hopefully someone can point out where I'm going wrong here.
Rich
Rich, Consider where your control column is at the point of stall, and from there, where is the tailplane? Now, with the tailplane fully up, where is the chord line for the tailplane? Now consider the relative airflow over the tailplane which, remember, has a downforce holding the nose up.
At the point of stall, the aircraft starts to descend, an immediate change in the relative airflow occurs over the tailplane, resulting in a sudden loss of tail down force. Thus, the nose pitches down. The couple of the forces merely ensures the nose down pitch with the lift behind the weight.
An important point to remember is that incorrect loading of the aircraft causing a rearward shift in the weight can result in a severe stall that may not be recoverable.
I hope this helps with your thinking. Kevin Patterson.
Why does the nose pitch down during a stall?
in Student Pilot & Further Learning
Posted
At the point of stall, the aircraft starts to descend, an immediate change in the relative airflow occurs over the tailplane, resulting in a sudden loss of tail down force. Thus, the nose pitches down. The couple of the forces merely ensures the nose down pitch with the lift behind the weight.
An important point to remember is that incorrect loading of the aircraft causing a rearward shift in the weight can result in a severe stall that may not be recoverable.
I hope this helps with your thinking. Kevin Patterson.