Basically I'm wondering if this is correct. Which essentially says that you need a torque to get the nose of the craft to turn and that this is provided by the rear tail surfaces.
After trying to simulate airplane flight in a game engine, I'm thinking that link is correct. Although airplane flight is rarely described like that.
If you just apply force in the direction of lift (and thrust), then during a roll, the horizontal component of lift causes the plane to get a velocity with a horizontal component. But the plane does not turn. The plane slips to the side while going forward. The horizontal component of lift does not stay perpendicular to the velocity vector so it doesn't move in a circle.
Imagine also a block sliding forward on ice (constant v) with a small thruster attached to its side (turned off). Now turn on the side thruster (pointed through cm). Does the block start turning in a circle or does it just get a horizontal component to it's velocity? Doesn't it need a torque, just like the plane to keep the thrust perpendicular to the velocity vector?
So am I out of my mind here or is this correct?
Best Answer
You're correct, the ice block will not turn automatically. It will require a torque. In aviation this is basically what is called coordinating a turn. With an airplane, if the pilot does not provide the necessary coordinating torque via rudder/elevator inputs, the torque will be generated automatically via the weathervane effect, which tends to align the fuselage with the velocity. So, you can effectively turn just by banking, if you're not anal about keeping your altitude and airspeed constant. In a helicopter, it's a different story, as the helicopter doesn't have much of a weathervane effect at least at low speeds. With a helicopter at low airspeed if you just bank without coordinating rudder then you just slide sideways.