“We know a little more than we did,” Curt reminded him. “I’ve had talks with some of the boys I know, and I’ve found out that the ones Griff associates with aren’t thought well of. And Bob has trailed him, several evenings, in spite of Lang’s warning to Griff, and Bob has told you that Griff always gets away on his motorcycle and goes somewhere that we can’t locate yet. But we know his character isn’t very high class, and his father still acts uneasy and preoccupied. So we have gained that much.”
“What good is it?” Al was unconvinced. “It doesn’t say what happened to Mr. Tredway. It hasn’t told us who is taking airplane parts. It doesn’t explain who tampered with the rudder cable in the Golden Dart—or why.”
“No,” Bob admitted. “That’s true, it doesn’t. But it’s the best we can do, for the present. And we never know when something may ‘break.’”
“Let’s keep on learning airplane technique,” suggested Curt. “We know we’ve gained there, anyhow.”
“Yes,” Al nodded. “I can name the different parts of a biplane without stumbling over any of them.” He did, “—fuselage; engine; propeller; upper and lower wing; cockpit and its cowling; struts and landing and flying wires; stabilizer, fin, elevator, rudder; ailerons; tail skid; and landing gear that Sandy calls the ‘trucks.’”
“Correct,” agreed Curt. “And they comprise five groupings, each one having a special purpose—the fuselage, the supporting structure for everything else. Everything is attached to that. Then——”
“The second group,” Bob cut in, “is the supporting surfaces, the wings. They sustain the whole weight in the air, and the flying wires take the lift of the wings as the air sustains them, and communicates it, with the struts helping, to the body.
“Well, in a way,” Bob changed the statement slightly. “The flying wires are to take the stress, and if it wasn’t for them the wings would tilt up at the ends or tips, like a ‘V.’ The flying wires take the stress in flying the same as the landing wires take the weight of the wings in landing; without the landing wires, when the ship came down the wings would crumple down over the crate like the two slanting sides of a tent or like the ‘V’ upside down.”
“Yes,” Al showed his knowledge, “and then there is the control group, the ailerons at the backs or trailing edges of the wings, to be moved upward or downward, to tilt the ship; and the rudder, to turn it sideways—and if it’s flying on its side the rudder is performing the office of the elevators and they of the rudder, because when it’s flying level the elevators are to tip its nose up for a climb or down for a glide; then there’s the fin and the stabilizers that give it balance and help to hold the whole ship in whatever position it is placed by the movable controls I just mentioned.”
“And with all those you have a glider,” agreed Bob. “The engine, and its ‘prop’ are for motive power, and the landing group, either wheels for the earth, or pontoons for the water, or both, combined, in an amphibian, for land-and-water use——”