“Don!” Chick, sensed a solution, having studied a good deal about the various points of airplane design, “remember that when a pontoon is in water, as it lifts, the suction of the surface increases and has a strong pull to keep it from leaving: that’s why they design a pontoon with a ‘step’ so the contact is with the top of the water, and not down in it.”
“That’s right,” Don agreed. “We’ll have to go forward a little as we lift. On land that wouldn’t be necessary. In water it may.”
The experiment was tried: he used the thrust-propeller, and in short order they were rising: then he cut out the forward speed, until he had made some tests of lifting speed with the horizontal blades.
“Here we go!” he cried finally. Go they did—up and forward.
“Aside from the handling of the upper fan,” he mused, “this isn’t much different from a slow cruising airplane. The tail and propeller control are similar—rudder and elevators; but I’ll have to remember the turn is made without ailerons to bank. We don’t have to bank on a turn. We just rudder around, and the upper blades keep us on a stable keel as we turn—here, we do it!”
Around swung the forward propeller, and Don directed the craft toward the higher levels on a slanting line that climbed it and also progressed it toward the airport.
He saw, when they came close to the open space, figures on the illuminated tower balcony, watching upward.
Someone blinked a flash lamp.
“That means ‘O.K.’” he murmured.
“We can put on our show!” cried Chick, also misinterpreting the signal that they did not pause to spell out in full.