John gives a very thorough pre-flight, covering all the basics of flight and club flight rules. I would like to have ALL new pilots see him first BEFORE starting dual-time with flight instructors.
by John Forester
These are short, summarized thoughts that the model flying instructor can use to instruct the student primary pilot during or before dual-control flight instruction.
Your transmitter has two sticks, left and right.
Move the left stick only forward and back, to control power. Forward, more power; Backward, less power. At the start, your instructor will tell you where to set the power. Later you will learn to modify it. When beginning you will fly at Cruise power, comfortably faster than necessary to stay up. That gives you a reserve of speed and power to keep you up when maneuvering.
The right stick controls the attitude of the plane. Right and Left movement controls the bank angle of the plane. Forward movement, Push, points the ship down; Backward movement, Pull, points the ship up. That’s what you see, but that is not important. The important function of Pull and Push is explained later.
In a plane in steady level flight, two pairs of forces balance each other. Engine Thrust balances Drag. Lift balances Weight (gravity). But you mustn’t think of Lift as always being straight up. Lift is always perpendicular to the wing, however tilted the wing is.
The wing creates Lift by pushing down the air that it passes through. Think of the wing as a flat plate being pushed through the air. The flat plate is sloped so that its leading edge is higher than the trailing edge. If that slope is zero, the flat plat won’t produce Lift. As that slope is increased, the air is pushed downward more vigorously and the amount of Lift increases.
Real wings aren’t flat plates; they have the same characteristics but with higher efficiency.
The important function of Push and Pull is to control the amount of Lift. Pull increases the wing’s slope, making more Lift but slowing you down. Push decreases the wing’s slope, decreasing Lift and speeding you up.
Angle of Attack
Every wing has a slope toward the wind at which it produces no Lift. That is called the Zero Angle of Attack (AOA). Since a plane has weight, it can fly only by using a positive AOA to generate Lift.
Paying attention to the AOA, which is indicated by how far back you have Pulled the stick, is extremely important. Too much Pull, with too little power, and the wing stalls, which means that Lift disappears.
Lift and Drag
Remember this well. You can’t get Lift without producing Drag. That’s a law of science. To get more Lift by increasing the angle of attack, you have to either slow down or use more power.
Just like a bicycle on a curve, a plane has to bank into a turn. To make a gentle circle to the right, move the stick gently Right until the plane has achieved a small banking angle, less than 10 degrees. At this moment the plane will enter a right circle. Lift, being perpendicular to the wing, will be pulling the plane towards the center of the circle, and the drag of the tail will be causing the plane’s body to turn around following the circle.
If you were to continue this for a full circle, you would see that the plane had lost altitude. To circle while maintaining altitude, you need more Lift, which means Pull, a little bit, on the right stick. For many primary planes, you Pull the stick about 1/4 of the distance you moved it Right (or Left, for a left circle).
This is a useful exercise for any student. Make a full circle, say right, followed by a full circle in the opposite direction, left. Each circle must maintain altitude, and be without bounce or drop as you switch from one circle to the opposite circle. This trains your coordination of Right or Left with Pull and then Push, so the plane moves smoothly.
Until now, you have been making gentle movements, climbing or turning, relying on the safety reserve of speed and power that you have when flying at cruising speed. If you needed much more lift, you might Pull much more, thus increasing the AOA to get more Lift. That’s fine for a bit, but when the wing gets to an AOA of about 18 degrees to its movement through the air, the air flow around it just tumbles into turbulence and Lift disappears. Then there’s no Lift to hold the plane up, and it falls. This is called Stalling. Unpleasant at any time, and very dangerous when near the ground.
While stalling is affected by load carried and speed of flight, the only thing that causes stalling is pointing the wing to too far up, which is done by Pulling the stick excessively when trying to get more Lift.
Remember this well. The way to end a stall is to Push the stick somewhat forward. That decreases the AOA until the wing gets a grip again on the air and the plane becomes controllable.
More Vigorous Movements
You are now ready to make more vigorous turns, turns with smaller radius. That means more bank angle (stick more to the side) and more Pull. Since Pull increases Lift, and increased Lift increases Drag, you need more Power to counter that increased Drag.
You need more Lift for two reasons. With increased Bank, Lift is no longer pointing directly away from Weight, gravity, so it has to be stronger to keep the plane in the air. To turn the plane quicker and sharper requires still more Lift to pull it around quicker. When the plane is banked 45 degrees in a turn you need about twice as much Lift and Power as for slowest level flight.
Therefore, before beginning practice in vigorous turns, increase Power, so you have excess Power available during the critical parts of the turn. Then practice Lazy Eights at higher and higher angles of bank until the plane feels uncertain. This depends on the Power you have available, and the general design of the plane. Aerobatic and fighter planes can stand higher angles of bank than can general aviation and trainer planes.
If you get into a stall, with the plane getting uncontrollable and falling, then Push somewhat, reducing the AOA, until the wings get a new grip on the air and the plane becomes controllable. You are likely then to have the nose down with still a lot of bank. First level the wings by sideways movement of the stick, then Pull until the plane is level again.
If your planehas sufficient Power to make loops, here’s how you do it. Start level flight with wings level. Go to full Power. Wait for speed to increase. Then Pull. The plane will make a loop. As it goes over the top, close the throttle. When it comes back to level, center the stick to level out and return to cruise Power. You should recognize that all around the loop, Lift is pulling the plane toward the center of the loop, just as in a turn it pulls the plane toward the center of the turn.
Turns at Low Speed and Altitude
Landing approaches are the most dangerous part of flying. You are flying slowly, using little Power or just gliding in. On the typical circuit you must make two 90 degree turns: Downwind leg to base leg, base leg to landing strip. Flying slowly you have very little reserve Speed or Power. That means that these turns must be made gently. If a turn is made too sharply, with little reserve speed or power, the plane will stall, and you don’t have sufficient height above the ground to recover.
On landing approach turns, limit banking and Pull to gentle levels because of the danger of stalling the plane at low speed and altitude.