Instead of hastening from ground work into flying, as he could have done, Hal went back into classes for a second course in engine work.
Because Hal showed promise, Major Weston laid the work on him, uncompromisingly made him dig for what he got. But after class hours, a friendship sprang up between the blond boy and the short, heavy-set pilot trainer. Engines were their meat!
Hal was beginning to master the intricacies of motors, from the old seven thousand part Spano Motor down through its more modern descendant, the three thousand part D. C. Motor.
Engine mechanism was marvelous, was complicated—too complicated. Even after he understood the wondrous power and pull in unison of the D. C., Hal’s brain rebelled somewhat at the involvement of even this latest build of motors. Man was smart to have made so complicated a thing—but man would have been more of a marvel to have made a simple thing that would perform the same work.
“But,” questioned Hal of his instructor-friend, “for the air motor, every ounce of weight removed means power saved; now what—what could be taken from such an engine, and still leave efficiency?”
“But what? But why?”
In their after-school confabs, Weston’s experience and Hal’s theory and hopes fought many an acrimonious friendly battle. Raynor, who as advanced-flying pilot was for the present out of Hal’s school sector, sometimes of a night joined in these air battles fought out on the ground. All manner of past and modern experiments came under the fire of their discussions. Aeronautical engine builders seemed to have tried out many varieties of motors. There were the long ago experiments with steam engines for airplanes. The engine itself could be made much lighter than the gasoline engine, but the fuel and water added so much weight that the whole combination was far too heavy for air purposes. Mercury and other liquids were tried out without much success. Then came gasoline and mercury-vapor turbines, fine in principle but somehow unsuccessful. There was a flaw that needed some genius to find it.
“The turbine principle is the coming change,” argued Weston. “If the turbine principle could be applied to an aeronautical engine, it would eradicate many of the present troubles.”
“But engine makers can’t seem to apply it,” contended Hal. “Seems to me,” he hazarded his next thought gingerly, “that the engine without batteries is going to be the thing. Batteries weigh an awful lot. How about this high-degree compressed fuel and the way it explodes under pressure in the cylinder—without the ordinary explosion by electric spark? That would cut out batteries and save weight—”
“Save battery weight, yes!” countered Weston out of his deeper knowledge, “but how about the five hundred pound pressure to the square inch needed to explode such engine fuel?”