Test Pilot

November 20, 2013

1. From reader John Ritchie: True or False? It is impossible for a jet fighter to shoot itself down by flying into its own gunfire.

2. Pilots are familiar with adverse yaw, a result of using ailerons, but what is adverse roll, and what causes it?

3. During October 1945, what well-known department store became the first such store to display airplanes for sale, and what type of airplanes did the store sell?

4. True or False? A radio aid to navigation used in the United States prior to the advent of the VOR (or “omni”) was the VRB, or voice radio beacon. The VRB broadcast in voice the bearing of an aircraft from the station.

5. From reader Brian Schiff: What is a vortilon?

6. True or False? Low-pressure troughs and high-pressure ridges associated with a jet stream in the Northern Hemisphere are situated north and south, respectively, of the jet.

7. From reader John Schmidt: A pilot is wearing a lapel pin called a “Lennie,” and he appears to be particularly proud of it. What does this pin represent?

8. What is a sub-cloud car and what type of aircraft were equipped with them?


Anwers

1. False. On September 21, 1956, test pilot Thomas Attridge shot himself down while flying a Grumman F–11F Tiger. He entered a shallow supersonic dive after test-firing his 20-mm cannons, outran his gunfire from below, and was hit by his own rounds. This disabled the engine, buckled the windscreen, and resulted in a crash landing.

2. When rudder is deflected, a horizontal aerodynamic force is created by the vertical stabilizer at a point usually above the longitudinal axis of the airplane. In some airplanes, this force can initially tend to roll the airplane opposite to the direction of rudder input. Applying left rudder, for example, can cause a right roll, and vice versa.

3. Macy’s (in Manhattan) displayed and offered for sale an ERCO Ercoupe in a showroom called “The Flight Deck.” The purchase price included delivery at the purchaser’s local airport and lessons leading to solo.

4. True. The recorded human voice was broadcast on a rotating beam transmitted on VHF and provided bearings from the station in 10-degree increments.

5. Sometimes called a stall fence, a vortilon (a contraction of vortex and pylon) is essentially a flat plate attached chordwise near the leading edge of a wing. Its purpose is to improve airflow at large angles of attack by reducing spanwise airflow, energizing the boundary layer, and delaying airflow separation.

6. True. The jet stream typically meanders snakelike in an easterly direction and forms the bottom (southerly) arcs of troughs and the top (northerly) arcs of ridges.

7. The Soaring Society of America awards a Lennie, a 2-Lennie, and a 3-Lennie pin to sailplane (glider) pilots who have climbed to altitudes of 25,000 feet, 35,000 feet, and 40,000 feet, respectively, in mountain-wave conditions during which lenticular clouds (“lennies”) are typically present.

8. A sub-cloud car was a small observation compartment attached to the bellies of some dirigibles, especially German Zeppelins during World War I. The car was lowered by cable during flight so that someone in the compartment could make weather, terrain, and troop observations in clear air while the mother ship hid from the enemy in cloud.