"The same; only they went the wrong way about it. This propeller, with this driving power behind it, practically gives the vertical ascent, especially when once flying speed has been obtained."
"Blitz, but it is wonderful!" concluded Max, his enthusiasm growing by leaps and bounds, as he continued his examination.
"Why, the propellers are made of steel, and so are the planes," exclaimed Carl, who was now carefully examining the material of which the aeroplane was made.
"Steel, tempered steel, every bit of it--fuselage, propellers, tail fin, rudders. There's not an ounce of wood about the Scorpion," returned the mentor.
"Then the danger of fire is lessened," ventured Max, whose one dread in the air had always been that of fire.
"That danger is eliminated," replied the chief, in a tone of certitude.
"Except by petrol. By the way, where are the petrol tanks?" exclaimed Carl, who had never missed them till now.
"There aren't any," replied the Rittmeister, smiling. "I was waiting for that question."
"No petrol tanks?" came the astonished cry from both the airmen at once.
"They're not necessary," returned the other; "and that's the greatest mystery of all."