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Can we come up with a really contrived case where we "zoom climb" without pitching up at all? Yes we can-- but the climb will be very brief. For example, let's say that we're pulling out of a loop. Let's say that we're "pulling" 4G's-- the Lift vector is four times the aircraft's Weight. Just before we reach a horizontal pitch attitude, the airspeed will typically be decreasing, meaning that Drag is greater than Thrust. As we continue to pull up, there will be an instant in time where the pitch attitude is exactly horizontal, but Lift is still much greater than Weight. At that instant, if we relax the back pressure and move the stick forward as needed to exactly freeze the aircraft's pitch attitude, the flight path will still continue to curve upward for a very brief interval of time, until the upward curve of the flight path decreases the angle-of-attack the wing to the point where Lift vector is equal to the Weight vector, or more precisely, the point where the Lift vector is equal to the component of the Weight vector that acts perpendicular to the flight path. At that instant the centripetal acceleration is zero. The linear acceleration cannot be zero-- as we continue to hold the pitch attitude of the fuselage constant, the airspeed will decrease, and then the flight path will curve downward again until it is exactly horizontal. When the Thrust vector is exactly horizontal, steady-state flight is only possible in the horizontal direction, not in the upward or downward direction. From the pilot's point of view, what has happened is that we've reach a level pitch attitude and then we've rather rapidly "unloaded" the wing to near 1-G condition and transitioned to approximately horizontal flight. The fact that the aircraft did climb very briefly with the fuselage exactly level would probably be impossible to detect without special instrumentation. But yes, technically, it is possible to achieve a very brief interval of climbing flight with the Thrust vector remaining exactly horizontal, and in fact something close to this happens almost every time we transition from a dive to an horizontal pitch attitude, unless we somehow manage to control the throttle in such a way that the airspeed remains exactly constant during the final portion of the pull-out.

Can we come up with a really contrived case where we "zoom climb" without pitching up at all? Yes we can-- but the climb will be very brief. For example, let's say that we're pulling out of a loop. Let's say that we're "pulling" 4G's-- the Lift vector is four times the aircraft's Weight. Just before we reach a horizontal pitch attitude, the airspeed will typically be decreasing, meaning that Drag is greater than Thrust. As we continue to pull up, there will be an instant in time where the pitch attitude is exactly horizontal, but Lift is still much greater than Weight. At that instant, if we relax the back pressure and move the stick forward as needed to exactly freeze the aircraft's pitch attitude, the flight path will still continue to curve upward for a very brief interval of time, until the upward curve of the flight path decreases the angle-of-attack of the wing to the point where Lift vector is equal to the Weight vector, or more precisely, the point where the Lift vector is equal to the component of the Weight vector that acts perpendicular to the flight path. At that instant the centripetal acceleration is zero. The linear acceleration cannot be zero-- as we continue to hold the pitch attitude of the fuselage constant, the airspeed will decrease, and then the flight path will curve downward again until it is exactly horizontal. When the Thrust vector is exactly horizontal, steady-state flight is only possible in the horizontal direction, not in the upward or downward direction. From the pilot's point of view, what has happened is that we've reach a level pitch attitude and then we've rather rapidly "unloaded" the wing to near 1-G condition and transitioned to approximately horizontal flight. The fact that the aircraft did climb very briefly with the fuselage exactly level would probably be impossible to detect without special instrumentation. But yes, technically, it is possible to achieve a very brief interval of climbing flight with the Thrust vector remaining exactly horizontal, and in fact something close to this happens almost every time we transition from a dive to an horizontal pitch attitude, unless we somehow manage to control the throttle in such a way that the airspeed remains exactly constant during the final portion of the pull-out.

Can we come up with a really contrived case where we "zoom climb" without pitching up at all? Yes we can. For example, let's say that we're pulling out of a loop. Let's say that we're "pulling" 4G's-- the Lift vector is four times the aircraft's Weight. Just before we reach a horizontal pitch attitude, the airspeed will typically be decreasing, meaning that Drag is greater than Thrust. As we continue to pull up, there will be an instant in time where the pitch attitude is exactly horizontal, but Lift is still much greater than Weight. At that instant, if we relax the back pressure and move the stick forward as needed to exactly freeze the aircraft's pitch attitude, the flight path will still continue to curve upward for a very brief interval of time, until the upward curve of the flight path decreases the angle-of-attack the wing to the point where Lift vector is equal to the Weight vector, or more precisely, the point where the Lift vector is equal to the component of the Weight vector that acts perpendicular to the flight path. At that instant the centripetal acceleration is zero. The linear acceleration cannot be zero-- as we continue to hold the pitch attitude of the fuselage constant, the airspeed will decrease, and then the flight path will curve downward again until it is exactly horizontal. When the Thrust vector is exactly horizontal, steady-state flight is only possible in the horizontal direction, not in the upward or downward direction. From the pilot's point of view, what has happened is that we've reach a level pitch attitude and then we've rather rapidly "unloaded" the wing to near 1-G condition and transitioned to approximately horizontal flight. The fact that the aircraft did climb very briefly with the fuselage exactly level would probably be impossible to detect without special instrumentation. But yes, technically, it is possible to achieve a very brief interval of climbing flight with the Thrust vector remaining exactly horizontal, and in fact something close to this happens almost every time we transition from a dive to an horizontal pitch attitude, unless we somehow manage to control the throttle in such a way that the airspeed remains exactly constant during the portion of the pull-out.

Can we come up with a really contrived case where we "zoom climb" without pitching up at all? Yes we can-- but the climb will be very brief. For example, let's say that we're pulling out of a loop. Let's say that we're "pulling" 4G's-- the Lift vector is four times the aircraft's Weight. Just before we reach a horizontal pitch attitude, the airspeed will typically be decreasing, meaning that Drag is greater than Thrust. As we continue to pull up, there will be an instant in time where the pitch attitude is exactly horizontal, but Lift is still much greater than Weight. At that instant, if we relax the back pressure and move the stick forward as needed to exactly freeze the aircraft's pitch attitude, the flight path will still continue to curve upward for a very brief interval of time, until the upward curve of the flight path decreases the angle-of-attack the wing to the point where Lift vector is equal to the Weight vector, or more precisely, the point where the Lift vector is equal to the component of the Weight vector that acts perpendicular to the flight path. At that instant the centripetal acceleration is zero. The linear acceleration cannot be zero-- as we continue to hold the pitch attitude of the fuselage constant, the airspeed will decrease, and then the flight path will curve downward again until it is exactly horizontal. When the Thrust vector is exactly horizontal, steady-state flight is only possible in the horizontal direction, not in the upward or downward direction. From the pilot's point of view, what has happened is that we've reach a level pitch attitude and then we've rather rapidly "unloaded" the wing to near 1-G condition and transitioned to approximately horizontal flight. The fact that the aircraft did climb very briefly with the fuselage exactly level would probably be impossible to detect without special instrumentation. But yes, technically, it is possible to achieve a very brief interval of climbing flight with the Thrust vector remaining exactly horizontal, and in fact something close to this happens almost every time we transition from a dive to an horizontal pitch attitude, unless we somehow manage to control the throttle in such a way that the airspeed remains exactly constant during the final portion of the pull-out.

And now a closing note to the closing note-- earlier, we stated "if the Thrust vector is pointing horizontally rather than upward, then we aren't climbing." We've also noted that a glider can be looped with no thrust at all. A powered plane can also be "zoom climbed" even if thrust is less than drag, but the airspeed will be decreasing. Note that during the "zoom climb", the thrust line is still usually pointing upward as a byproduct of the curvature of the flight path in the zoom climb.

Can we come up with a really contrived case where we "zoom climb" without pitching up at all? Yes we can. For example, let's say that we're pulling out of a loop. Let's say that we're "pulling" 4G's-- the lift vector is four times the aircraft's weight. Just before we reach a horizontal pitch attitude, the airspeed will typically be decreasing, meaning that drag is greater than thrust. As we continue to pull up, there will be an instant in time where the pitch attitude is exactly horizontal, but lift is still much greater than weight. At that instant, if we relax the back pressure and move the stick forward as needed to exactly freeze the aircraft's pitch attitude, the flight path will still continue to curve upward for a very brief interval of time, until the upward curve of the flight path decreases the angle-of-attack the wing to the point where Lift vector is equal to the Weight vector, or more precisely, the point where the Lift vector is equal to the component of the Weight vector that acts perpendicular to the flight path. At that instant the centripetal acceleration is zero. The linear acceleration cannot be zero-- as we continue to hold the pitch attitude of the fuselage constant, the airspeed will decrease, and then the flight path will curve downward again until it is exactly horizontal. When the Thrust vector is exactly horizontal, steady-state flight is only possible in the horizontal direction, not in the upward or downward direction. From the pilot's point of view, what has happened is that we've reach a level pitch attitude and then we've rather rapidly "unloaded" the wing to near 1-G condition and transitioned to approximately horizontal flight. The fact that the aircraft did climb very briefly with the fuselage exactly level would probably be impossible to detect without special instrumentation. But yes, technically, it is possible to achieve a very brief interval of climbing flight with the thrust vector remaining exactly horizontal, and in fact something close to this happens almost every time we transition from a dive to an exactly horizontal pitch attitude, unless we somehow manage to control the throttle in such a way that thrust remains exactly equal to drag and airspeed remains exactly constant during the pull-out.

And now a closing note to the closing note-- earlier, we stated "if the Thrust vector is pointing horizontally rather than upward, then we aren't climbing." We've also noted that a glider can be looped with no Thrust at all. A powered plane can also be "zoom climbed" even if Thrust is less than drag, but the airspeed will be decreasing. Note that during the "zoom climb", the thrust line is still usually pointing upward.

Can we come up with a really contrived case where we "zoom climb" without pitching up at all? Yes we can. For example, let's say that we're pulling out of a loop. Let's say that we're "pulling" 4G's-- the Lift vector is four times the aircraft's Weight. Just before we reach a horizontal pitch attitude, the airspeed will typically be decreasing, meaning that Drag is greater than Thrust. As we continue to pull up, there will be an instant in time where the pitch attitude is exactly horizontal, but Lift is still much greater than Weight. At that instant, if we relax the back pressure and move the stick forward as needed to exactly freeze the aircraft's pitch attitude, the flight path will still continue to curve upward for a very brief interval of time, until the upward curve of the flight path decreases the angle-of-attack the wing to the point where Lift vector is equal to the Weight vector, or more precisely, the point where the Lift vector is equal to the component of the Weight vector that acts perpendicular to the flight path. At that instant the centripetal acceleration is zero. The linear acceleration cannot be zero-- as we continue to hold the pitch attitude of the fuselage constant, the airspeed will decrease, and then the flight path will curve downward again until it is exactly horizontal. When the Thrust vector is exactly horizontal, steady-state flight is only possible in the horizontal direction, not in the upward or downward direction. From the pilot's point of view, what has happened is that we've reach a level pitch attitude and then we've rather rapidly "unloaded" the wing to near 1-G condition and transitioned to approximately horizontal flight. The fact that the aircraft did climb very briefly with the fuselage exactly level would probably be impossible to detect without special instrumentation. But yes, technically, it is possible to achieve a very brief interval of climbing flight with the Thrust vector remaining exactly horizontal, and in fact something close to this happens almost every time we transition from a dive to an horizontal pitch attitude, unless we somehow manage to control the throttle in such a way that the airspeed remains exactly constant during the portion of the pull-out.