Landing Gear & Ground Handling

The errors this method actually invites, and what it does about each. Every one of them is already a warning somewhere — in a note that appears when your own figures trip it, in the scope statement, or in the equations behind the page. Collected here so you can read them before you need them.

Moving the mains to fix the turnover angle. The lever depends on the nose or tail wheel distance, not the main wheel distance — which is the opposite of what almost everyone assumes. Widening the track is the only change that lowers the turnover angle without costing something else.

Reading two warnings where there is one defect. On a tricycle, a nose wheel below its load band and an aeroplane that will sit on its tail are the same thing said twice: the mains are barely behind the centre of gravity. The sheet reports one cause rather than two symptoms.

Passing every angle and calling the gear designed. Nothing here is dynamic. Landing impact, spring travel, tyre deflection, the sideways load in a ground loop, axle strength and shimmy are all outside it. A leg that passes every angle on this sheet can still fail on the first arrival, because arrival energy is not geometry.

Taking the crosswind figure as a limit. It is a static moment balance with a compiled side-force coefficient of 1.0 for a bluff broadside shape. Treat it as the right order of magnitude, not as a threshold to fly to.

Measuring propeller clearance with the model level. The angle that matters is rotation about one main wheel — a wheel dropping into a rut, which is the failure models actually suffer. 25 mm of clearance is the least worth having on tarmac and 50 mm on grass.