Stability, Rectangular Courses, and Circular Turns
The ground school lesson was important since it went over the important factors to keeping a plane running smoothly in the air in the way of stability.
When manufactures design a plane to be stable or unstable, the big factors to consider are the different axes of rotation. The axes of rotation are what control how the plane will fly. There are three and they’re the following:
- Lateral – Used to control pitch, controlled by the elevators
- Longitudinal – Used to control roll, controlled by the ailerons
- Vertical – Used to control yaw, controlled by the rudders
The location that these axes of rotation meet is the center of gravity for the plane. Center of gravity is the average location of the weight of an object. This means that the heaviest point of the plane is in this location and is the spot that must be countered the most by lift. The point of lift is called the Center of Lift or Center of Pressure which is behind the center of gravity.
Another important component to stability is the dihedral. The dihedral is the upward angle of the airplanes wings with respect to the horizontal. When an aircraft with dihedral is yawing to the left, the dihedral causes the left wing to experience a greater angle of attack, which increases lift. This increased lift tends to return the aircraft to level flight.
When a plane is either too far forward or backwards due to weight or other conditions, the plane can become uncoordinated due to the shift of the center of gravity. When the center of gravity is towards the front of the plane, the plane is very stable making it hard to maneuver effectively. When the center of gravity moves towards the back of the plane, the stability goes away and makes for a very difficult plane to maneuver once again because the plane goes out of control. To control your coordination, you should keep your foot near the rudder controls and make sure that we stay in the indicated spot on the coordination dial.
We finished discussing stability by going over static and dynamic stability. Static stability is the initial tendency, and dynamic stability is the tendency over time. Each stability type has positive direction, neutral direction, and negative.
Positive is the direction a marble would want to go if rolled up in a bowl. Over time it would lose velocity and stop.
Neutral is how the ball would roll if on a flat friction-less surface. Over time it would keep going and going without speeding up or slowing down.
Negative is how the ball would roll down a hill or a slope. It would start slow but over time would increase velocity.
For your regular cruising or commercial plane, we want a positive stability. Planes which are for show or in the military tend to be in the neutral or negative zone.
Ground school was finished by discussing how to recover from a spin. A spin is a stall where we fall in a spiral instead of a nice steady straight down fall. Here are the instructions to recover from a spin:
- Throttle Idle
- Opposite Rudder
- Ailerons to Neutral
- Hard push on yolk forward (nose down)
- Smoothly return to level flight
If all goes well, we should return to some level flying and go on our marry way.
Up in the Air
While getting ready to fly, I am finding I am getting much better at my pre-flight checklists. Also, I’m getting a lot more comfortable with flying! I even took off again and feel much better about it and am looking forward to my first solo! During the flight we went over some ground reference maneuvers (pick a point and use it to guide) and practiced stalls.
To pass all these maneuvers, I need to do the following:
- Determine Wind Direction
- Get into cruise flight (2300 RPM, 110 KIAS)
- +/- 100 ft Altitude
- +/- 10 KIAS
- Entry/Exit heading +/- 10 degrees
This maneuver has us practice flying in a flight pattern. We go to around 600 to 1000 AGL and fly around a field the same distance from its edges. This allows us to practice crabbing (turning into or away from the wind while flying in the cross), and to also practice general flying into the wind around a runway. I found it to be fun and pretty easy to get down.
Turns Around A Point
I really enjoyed this maneuver due to the amount of turning. What happens is you pick a reference point on the ground and around 600-1000 feet, you fly around the point keeping the distance between the plane and the reference point the same (radius). This isn’t too difficult when there isn’t wind since it is just a 360 turn. When the wind is present, this becomes a lot of corrections and going between shallow and steep banks to keep on track. Lots of fun!
S Turns, like the Turns Around A Point maneuver, are practicing turns. Difference here though is that instead of one reference point, you use a horizontal line (a road) and two different points. You fly a half circle around one point, and then continue the circle by flying the other direction to make another half turn. One left (or right) and then one right (or left).
The lesson was quite a lot of fun overall and like I said, I’m definitely getting better and still having an awesome time!
September 15, 2010 / Jason /
Categories: Private Pilot Completion
- Total Flight Time: 218.5 Hours
- Pilot In Command Time: 125.7 Hours
- Solo Time: 100.8 Hours
- >50NM Cross Country Time: 60.5 Hours
- >50NM Cross Country Time (Solo): 27.8 Hours
- Night Time: 7.1 Hours
- Simulated Instrument Time: 4.8 Hours
- Landings (Day/Night): 521 (499/22)
- Flight Training Received: 92.8 Hours
- Ground Training Received: 30.8 Hours