- #1
jernejk
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Dear all,
I'm a RC-airplane pilot with basic understanding of physics.
Recently I've been studying basic aerodynamics and I think I understand the basics.
However, I don't entirely understand why an airplane performs a loop and I can't find any references about it. Here's my current breakdown:
- for practical reasons, let's have a glider in a vertical dive
- nil wind
- we'll assume that the glider is flying at terminal velocity, so that weight and drag are neutral
My understanding of the situation:
- resultant of weight and drag is zero
- the wings still produce lift, perpendicular to the relative wind, so the lift vector is parallel to the horizon
- there is no opposite force to the lift
What happens (in a very short time frame, of course):
- the lift starts pulling the airplane
- center of mass moves further down and to the side (due to lift)
- the movement perpendicular to the wings generates drag on the horizontal tail, which in turns generates troque an rotates the plane over pitch axis
- because of this rotation, the airplane doesn't change the angle of af attack
- at the end of the time frame the situation is exactly the same as at the beginning, so here we go again.. and again.. and we perform a loop! (I know, the weight vector changes the direction and it needs to be accounted for)
Are my assumptions correct? Could someone provide accurate information?
TIA
Jernej
I'm a RC-airplane pilot with basic understanding of physics.
Recently I've been studying basic aerodynamics and I think I understand the basics.
However, I don't entirely understand why an airplane performs a loop and I can't find any references about it. Here's my current breakdown:
- for practical reasons, let's have a glider in a vertical dive
- nil wind
- we'll assume that the glider is flying at terminal velocity, so that weight and drag are neutral
My understanding of the situation:
- resultant of weight and drag is zero
- the wings still produce lift, perpendicular to the relative wind, so the lift vector is parallel to the horizon
- there is no opposite force to the lift
What happens (in a very short time frame, of course):
- the lift starts pulling the airplane
- center of mass moves further down and to the side (due to lift)
- the movement perpendicular to the wings generates drag on the horizontal tail, which in turns generates troque an rotates the plane over pitch axis
- because of this rotation, the airplane doesn't change the angle of af attack
- at the end of the time frame the situation is exactly the same as at the beginning, so here we go again.. and again.. and we perform a loop! (I know, the weight vector changes the direction and it needs to be accounted for)
Are my assumptions correct? Could someone provide accurate information?
TIA
Jernej