DUD--A condition of being without life or energy. An engine may be dud; a day may be dud for flying. A shell which will not explode is a dud. A pilot may be a dud, without skill. It is almost a synonym for washout. FLATTEN Out--To come out of a gliding angle into a horizontal glide a few feet from the ground before making a landing. The machine loses flying speed on a flat glide, and settles to the ground. FLYING SPEED--Speed of a plane fast enough to create lift with its wing surfaces. This varies with the type of plane from forty-five miles an hour as a minimum to the faster scout machines which require seventy miles an hour to carry them through the air. When a machine loses flying speed, due to stalling, it is in a dangerous situation, and flying speed must be recovered by gliding, or the machine will fall into a spin and crash out of control. FORCED LANDING--Any landing for reasons beyond the control of a pilot is known as a forced landing. Engine failure is chiefly responsible. Once the machine loses its power it must go into a glide to maintain its stability, and at the end of the glide it must land on water, trees, fields, or roofs of houses in towns. FUSELAGE--This word, meaning the body of a machine, came over from the French. The cockpits, controls, and gasolene-tanks are usually carried in the fuselage. HOP--Any flight in an airplane or seaplane is a hop. A hop may last five minutes or fifteen hours. JOY-STICK--The control-stick of an airplane was invented by a man named Joyce, and for a while it was spoken of as the Joyce-stick, later being shortened to the present form. It operates the ailerons and elevators. LANDFALL--A sight of land by a seaplane or dirigible which has been flying over an ocean course. An aviator who has been regulating his flight by instruments will check up his navigation on the first landfall. PANCAKE--An extremely slow landing is known as a pancake landing. The machine almost comes to a stop about ten feet off the ground, and with the loss of her speed drops flat. There is little forward motion, and this kind of landing is used in coming down in plowed fields or standing grain. Jules Vedrines made his landing on the roof of the Galeries Lafayette in Paris by "pancaking." SIDE-SLIP--The side movement of a plane as it goes forward. On an improperly made turn a machine may side-slip out--that is, in the direction of its previous motion, like skidding. It may side-slip in, toward the center of the turn, due to the fact that it is turned too steeply for the degree of the turn. Side-slipping on a straight glide is a convenient method of losing height before a landing.