Test Pilot

1. From reader Joseph Barber: When a military student pilot during World War I made an emergency, off-airport landing in a Curtiss JN–4 Jenny, how did he provide his location to those who could provide rescue?

2. True or False? Manifold pressure gauges are required on airplanes powered by piston engines equipped with constant-speed propellers.

3. From reader George Shanks: The first midair collision between two airliners occurred over
a. France.
b. the Grand Canyon.
c. Southern California.
d. Waxahatchie, Texas.

4. A flash of lightning lasts for only an instant. Why does thunder, which is the sound made by lightning, usually last so much longer?

5. From reader John Schmidt: In aviation parlance, what is a Jesus nut?

6. When scud running, why is it that a pilot often is deceived into believing that the weather ahead of the airplane usually is better than the weather behind?

7. From reader Brian Schiff: During his grueling flight to Paris, Charles Lindbergh cogitated about how it was possible for his nine-cylinder, four-stroke, radial engine to endure so many punishing “explosions” (power strokes) without failing. Assuming that his Wright Whirlwind engine had been operated at 1,800 rpm throughout the 33-hour, 30-minute flight, how many “explosions” did it produce?

8. True or False? During World War II, some of Germany’s jet fighters were equipped with guided missiles.

1. Carrier pigeons often were carried on cross-country flights. They were released following a forced landing to relay a pilot’s whereabouts.

2. False. Manifold pressure gauges are required only for “altitude engines,” which are those equipped with turbo- or superchargers.

3. a. A French Farman F.60 Goliath and a British de Havilland DH.18A (both biplanes) collided at 500 feet in mist and drizzle over Picardie, France, on April 7, 1922.

4. Thunder travels at the speed of sound, which is much slower than the speed of light. The initial sound of thunder is generated by that part of the lightning bolt closest to the observer, while the last sound of a thunderclap is made by the most distant part of the lightning bolt. Echoing plays a minor role, depending on the nature of the terrain.

5. The Jesus nut (or pin) is the nut that secures the main rotor on some helicopters, especially earlier designs. If this nut comes off and the main rotor detaches—well, now you know why the nut was so named. It also is used as a term for any single point of failure.

6. While moving forward, ground objects behind the aircraft disappear in the veil of reduced visibility, creating the illusion that visibility is worsening behind the aircraft. When looking ahead, conditions seem to improve—even though they are not—because forward motion causes progressively more terrain to come into view.

7. A nine-cylinder engine produces nine power strokes every two revolutions of the propeller. This equates to 8,100 power strokes every 1,800 revolutions (or every minute). During a 2,010-minute flight, therefore, the engine would produce 16,281,000 power strokes (or “explosions”).

8. True. After being fired, the missile pulled out and unwound a lengthy wire from a drum within the aircraft. As the wire played out, the pilot could electronically and visually guide the missile to its target.

Illustration by John Holms