Page:The Fun of It.pdf/164

134 For experts can make giros do seemingly easy stunts that novices couldn’t possibly duplicate—a truism which holds good for any skilled pastime.

After I had played with the autogiro for several hours at different times, I was given the chance to try an altitude hop. No one knew exactly how high a stock model could climb. So it was suggested that I take one upstairs and keep on going until it would go no farther. The “ceiling” of an air­plane is as much performance data as speed. Auto­mobile, motor boat and airplane manufacturers all find it valuable to check theoretical calculations with practical demonstrations.

Even though simple in itself, any official test re­quires more preparation than might be supposed. For instance, a representative of the National Aeronautic Association in Washington must be called to install the barograph. This instrument registers altitude and also shows the time consumed on the flight as recorded on a revolving drum. The barograph must be sealed and hung carefully on rubber shock cords in the cockpit. After use, it is calibrated by the United States Bureau of Stand­ards—that is, the actual height attained is deter­mined.

For this official test, besides the barograph, Itook along a bottle of oxygen. Beyond sixteen thousand feet it is well to have some on tap if a pilot intends to stay aloft a long time or to go higher. As it turned out, I reached only 18,415 feet and my lungs seemed to do the job unassisted.