surface at the optimum angle to the surface

of the water. Like the wing of an aircraft, the

angle of attack would affect its efficiency. He

reckoned that we needed it to sit up from the

rear to the nose at an angle of no more than

4.5°. On a boat, any more than that and you

would be wasting thrust trying to push the

whole thing into the air. If you dropped too far

below that, then you would be wasting thrust

by ploughing the thing down into the water.

Once again, we were talking about achieving

the perfect balance to get maximum speed

across the water from the thrust available.

If I got my balance right, the front

wheel would take care of itself.

The planing surface would have to be kept as

light as possible, but it would be taking a real

pounding, so it also needed to be strong. Charlie

planned to use aluminium for the outer surface

of the plane, reinforced with aluminium spars

running down each side and ribs running

across the inner ‘hull’ like the bulkheads of a

ship. The front of the plane would have to

curve upwards to make sure that it didn’t dig

into the water and force the bike down rather

than up. Instead of ending abruptly after the

main body, the plane would be forked at the

rear with a trailing arm running either side of

the rear wheel.

Right: Charlie shows roughly

where the planing surface

will go and that we want a

rear ‘paddle’ tyre.

152   hydroplaning motorbike