Performance - Introduction — Page 136, Lesson 157

We're starting a new section of the book now — the Performance Introduction. This is where we define the precise, regulatory vocabulary that governs everything we'll do in performance engineering. These aren't casual terms; they're legal and technical definitions from the certification world, and you need to know them exactly. Let me walk you through them in order. First, Instrument. This is a device using an internal mechanism to show visually or aurally the attitude, altitude, or operation of an aircraft or aircraft part. It includes electronic devices for automatically controlling an aircraft in flight. So think of it as the broad legal definition — anything that displays or even automatically controls, whether you see it or hear it. Next, Landing Distance Available. This is the distance from the point on the surface of the aerodrome above which the aeroplane can commence its landing, having regard to the obstructions in its approach path, to the nearest point in the direction of landing at which the surface of the aerodrome is incapable of bearing the weight of the aeroplane under normal operating conditions, or at which there is an obstacle capable of affecting the safety of the aeroplane. In short, it's the runway length from one threshold to another — the usable landing distance you can count on. Now, two speed limits involving the landing gear. Landing Gear Extended Speed is the maximum speed at which an aircraft can be safely flown with the landing gear extended. Landing Gear Operating Speed is the maximum speed at which the landing gear can be safely extended or retracted. Notice the distinction — one is for flying with gear down, the other is for the actual act of moving the gear. Then we have Landing Minimum Control Speed. This is the minimum speed with a wing engine inoperative where it is possible to decrease thrust to idle or increase thrust to maximum take-off without encountering dangerous flight characteristics. So with one engine out on a wing, you must be able to reduce power or add full power and still stay safe. Large Aeroplane — this is an aeroplane of more than 5700 kg maximum certificated take-off weight. And importantly, the category 'Large Aeroplane' does not include the commuter aeroplane category. So it's a specific regulatory threshold. Lift — that force acting on an aerofoil which is at right angles to the direction of the airflow. Simple, but fundamental. Load Factor — the ratio of a specified load to the total weight of the aircraft. The specified load is expressed in terms of any of the following: aerodynamic forces, inertia forces, or ground or water reactions. So it's a ratio — how many g's you're pulling, essentially. Mach Number — the ratio of true airspeed to the Local Speed of Sound, which we abbreviate LSS. Manoeuvre Ceiling — the pressure altitude that provides a 0.3 g margin to both the high speed buffet and the low speed buffet. So it's the altitude where you have that 0.3 g cushion on both sides — not too fast, not too slow. Maximum Brake Energy Speed — the maximum speed on the ground from which an aeroplane can safely stop within the energy capabilities of the brakes. This is about the brakes' ability to absorb energy, not just stopping distance. Then two power settings. Maximum Continuous Power — the power identified in the performance data for use during periods of unrestricted duration. Maximum Continuous Thrust — the thrust identified in the performance data for use during periods of unrestricted duration. Both are for unlimited time use — that's the key qualifier. Maximum Structural Take-off Mass — the maximum permissible total mass of an aeroplane at the start of the take-off run. Maximum Structural Landing Mass — the maximum permissible total mass of an aeroplane on landing, under normal circumstances. Minimum Control Speed — the minimum speed at which the aeroplane is directionally controllable with the critical engine inoperative and the remaining engines at take-off thrust. Note this is different from the landing version — here it's about directional control with the critical engine out and the rest at full take-off power. Finally, Minimum Unstick Speed — the minimum speed demonstrated for each combination of weight, thrust, and configuration at which a safe take-off has been demonstrated. It's a demonstrated value, specific to each weight, thrust, and configuration. That's the full set of definitions for this introduction. Each one is a building block for the performance calculations we'll do — take-off, climb, landing, and the limits that keep you safe.