| (1) Propeller Torque effect (PTE)
As the prop spins anti-clockwise (as viewed from behind) on most pusher prop configurations, the engine tends to want to spin in the opposite direction, due to the drag induced by the blades, as well as the inertia of prop, crankshaft and flywheel, during acceleration. Imagine if you held the blades still (resisted their rotation) and pulled the starter rope slowly. Because the prop cannot turn, the engine will turn instead, albeit in the opposite direction. In a similar fashion, the prop is to a small extend being "held back", so that force is absorbed by the tendency of the motor to rotate clockwise. The amount of Propeller Torque Effect, depends on prop mass, prop diameter, prop pitch, and prop RPM (engine RPM over Redrive ratio), but is basically directly related to available power. More power, means (unfortunately) more Propeller Torque Effect. This has the effect of lowering your right-shoulder, and lifting your left shoulder, which in turn produces a right-roll or banking effect on your wing, which then tends to turn to the right. You can counter this a number of ways, which we split into two categories: a)Passive counters: Those you design in, or set before take-off. e.g. set the right carabiner higher than the left, so that in flight, the two are more equal (or longer carab on right side); or pack any extra gear (tools, oil, camera, etc) on the left side; or your motor and/or harness may have some asymmetry built-in; or you can increase any cross-overs or cross-bracing present. b)Active counters: Those the pilot can induce in flight: including leftside weightshift, left counter-steer, asymmetric trim setting (slower on left side), or differential speedbar (more weight on left side), or any combination of these. Warning!!!! Any amount of brake you use in flight, especially on full power (e.g. takeoff and climbout), is too much brake! This is due to the thrust being several meters below the wing, resulting in a very positive angle of attack on the wing. A powered paraglider flies best with ZERO brake!!!!! So, if your torque induced turn is excessive and you try to counter with just left brake, you will very likely stall the left wing! We try to takeoff allowing for the lots of spare space to the right, and allow the wing to slowly turn to the right during climbout, slowly circling the takeoff field, until safe cruise height is reached, then backoff power and resume straight and level flight. The other two effects are often confused and mistaken for each other: If you rotate in the yaw axis until you are not facing the same way as the wing, you may be in serious trouble, especially if this happens just after launch. This rotation can be one of two things: 1) Gyroscopic Precession, or 2) Asymmetric Blade Thrust |