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Sunday 8th November 2009
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Brainteasers Interactive Quiz #49:
Basic Aerodynamics

Knowledge of basic aerodynamics is necessary for anybody wishing to obtain a pilot certificate. As the years go by, many pilots fail to refresh their knowledge of this subject, or to increase it beyond the simple explanations of lift, weight, thrust, and drag. Assess your aerodynamic knowledge by trying your hand at Irv Siegel's latest online quiz.

by Irv Siegel

NASA's Glenn Learning Technologies Project offers a Beginner's Guide to Aerodynamics at http://www.grc.nasa.gov/WWW/K-12/airplane/bga.html. The questions on this quiz are based on the information available from that guide.

1. Of the two methods of explaining the creation of lift (the
a. The "Bernoulli" position
across the wing, and the "Newton" position that lift is the reaction
b. The "Newton" position
c. Neither position
d. Both positions
force on a body caused by deflecting a flow of gas), which offers a complete
mathematical explanation?

2. Is it more fuel efficient to generate high thrust by accelerating a large
a. large mass by a small amount
amount?


b. small mass by a large amount
c. The two methods are equal in terms of fuel efficiency.
mass of gas by a small amount, or by accelerating a small mass of gas by a large
3. What are generally considered the principal propulsion systems?
a. propeller, ramjet, rocket, and turbine (or jet)
b. reciprocating, rotary, and turbocharged
c. airflow, inertial, and traction
4. The phrase, "density times the square of the velocity divided by
a. Total lift
b. The lift coefficient
c. Dynamic Pressure
two," is the definition of

5. When calculating the drag of an aircraft, one of the terms in the drag
a. the total surface area of the aircraft.
b. the frontal area of the aircraft that is perpendicular to the flow
c. the same wing area used to derive the lift coefficient.
d. We are free to use any area that can be easily measured.
direction.


equation is A, or reference area. The reference area is

6. What is Newton's first law of motion?
a. For every action, there is an equal and opposite re-action.
b. Force is equal to the change in momentum (mV) per change in time. (For a
c. Every object persists in its state of rest or uniform motion in a straight
constant mass, force equals mass times acceleration. F = ma).


d. As an object's speed increases, its mass increases and its length (in the
direction of travel) decreases.


line unless it is compelled to change that state by forces impressed on it.

7. We usually assume that an aircraft moves from one point to another as if
a. lift.
all the mass of the aircraft were collected into a single point called the
b. gravity.
c. motion.
center of


d. weight.
e. balance.
8. For many years it was considered impossible to fly an aircraft faster than
Mach 1 (the speed of sound). Part of the difficulty lay with the fact that as
a. the pilot's mental and physical responses slow down.
airspeed approaches the speed of sound


b. the weight of the aircraft increases by a substantial amount.
c. there is considerable added drag due to the compressibility effect.
d. the high "g" load tends to overstress the aircraft.
9. The speed of sound at sea level is 1116 feet per second. The speed of
a. 1068 fps
b. 968 fps
c. 868 fps
d. 768 fps
sea level to 100,000', what is the lowest speed of sound?


sound decreases as the temperature decreases. In the standard atmosphere from
10. What is the relationship between the lift over drag ratio (L/D) and the
a. L/D is always greater than Cl/Cd.
b. L/D is always less than Cl/Cd.
c. L/D is always equal to Cl/Cd.
lift coefficient to drag coefficient ratio (Cl/Cd)?