### Flight Model

The modeller's objective is to find the right balance between accuracy in critical situations and reasonable accuracy at other times. An airliner will have different priorities compared with a fighter: it is not necessary for an airliner to be aerobatic, but it is important that it behaves realistically during take-off and landing, and that real routes can be flown without running out of fuel.

It took years to collect enough information: dimensions, weights, aerofoils. Flying manuals contained graphs on performance, the Operating Data manual contained climb, cruise and descent tables for every permutation of weight, altitude and temperature, and a Rolls-Royce manual showed the power and fuel consumption curves for the Avon engines. The elusive figure was the drag caused by the engines being in the wing root.

Therefore I arranged a test schedule to derive a realistic drag figure from known performance.

Test | Properties | ||||
---|---|---|---|---|---|

1. | Stall | Lift | |||

2. | Unstick | Lift | Thrust | Drag | |

3. | Climb | Lift | Thrust | Drag | Fuel |

4. | Cruise | Lift | Thrust | Drag | Fuel |

5. | Descent | Lift | Thrust | Drag | Fuel |

6. | Approach | Lift | Thrust | Drag |

Stall tests established the maximum lift from the aerofoils and flaps, while unstick and landing tests confirmed them in a practical situation. There was no single test where drag could be isolated, so a reasonable compromise was made between climb, cruise and descent.