Panels White muslin, cut into various shapes, to designate positions of various headquarters, such as Regiment, Brigade, etc. When spread on the ground, pilots could see them and report positions. It was extremely difficult to get ground units to display them, since enemy planes, seeing them, could give location to their artillery. P.C. Post of Command. Applied to any headquarters company on up. _Poilu_ French private soldier. Prop Propeller. Pursuit pilot Pilot of combat plane. Put the wind up To frighten; to cause to lose courage or morale. Revving To accelerate motor rapidly. Ring sights Type of sight designed to make it possible to get on a rapidly moving target. Much time was spent in training pilots in gunnery and proper understanding of ring sights. R.F.C. British Royal Flying Corps. Saw bones Army surgeon. Sent west, Going west To be killed, to die. Side slipping To slip off the wing. Solo First flight student pilot makes alone. Spandau German machine guns used on combat planes. Twin guns, frequently, with single control. Stall To climb so rapidly as to stall the motor, putting upon it a load heavier than it can continue to pull. If care is not taken to ease off, plane will go into a spin. Tarmac The line of departure on the field. Often applied to the entire field. Toot sweet _Tout de suite_--French phrase, adopted by Americans. Quickly, hurry up, at once. Tri-plane German planes, especially Fokker, had short fin-like projections under the usual planes, and while quite short, and not a true plane, gave the ship the name of tri-plane. Were quite fast, good climbers, and manoeuvred easily. Upstairs Generally applied to high altitude flights. Sometimes applied to any flight, regardless of altitude. Very light pistol A type of pistol used to fire a shell somewhat larger than a 12 gauge shotgun shell, and which contained luminous star signals, such as red stars, green stars, white stars, etc. The meaning of the signal depended upon the color and number of these floating stars.