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Alan Druschitz, winner of this quiz and also the young man holding
the trophy in the photo, wrote recently to request that I scan and
post this R/C Sailplane Quiz that appeared in the October 1974 edition
of American Aircraft Modeler. It is always nice to
get a note from someone who appears in image and/or print form in
the old articles. It has been 40 years since the event, which makes
Mr. Druschitz about st two years older than me. To win the contest,
he answered 9 out of 10 of the questions correctly, and also took
1st place in the Jr./Sr. Team event at the
5th Annual R/C Soaring NATS. BTW, Alan also placed 7th place
overall, 1st place in Jr./Sr., and won the 1st Felix Pawlawksi
memorial award that year
R/C Sailplane Quiz
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Alan Druschitz, 18, receives the first Felix Pawlawski
Memorial Trophy at the 1974 RC Soaring Nationals. He answered
9 of 10 correctly. (Photo by Bill Coons)
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Do you know as much about theory and flight as an 18-year-old?
At the 1974 S.O.A.R. Nats (See page 12 for the contest story),
a new and innovative award was added to the many laurels a contestant
could garner. This was the Felix Pawlawski Memorial Trophy, awarded
to the Junior/Senior who scored highest on the following exam, and
also placed within the top 20% in flight scores.
Gordon Pearson, prime motivator for the award, presented the
test in cooperation with the University of Michigan Department of
Aerospace Engineering. Gordon, who helped design and write the exam,
had numerous requests from other contestants for copies.
One glance at the questions showed the test to be a real mind-bender,
and something to be shared with everyone. Here's your chance to
find out if you're as knowledgeable as the University of Michigan
thinks a pilot under age 19 should be. Alan Druschitz scored 9 out
of 10. He also flew a 2-minute Precision round of 2:01 with a 100-point
landing, just to give you an idea of this young man's mettle.
This is a closed-book exam. No cheating - it's on the honor system.
Answers next month
(shown at bottom of page).
(1) The airfoil section sketched below has various pressures
over its surface. Which point is at the highest pressure? (Circle
one.)
A
B C D
(2) In the preceding figure, which point is at the lowest pressure?
(Circle one.)
A
B C D
(3) As the speed of an airplane increases, what must happen to
the angle of attack to maintain level flight? (Circle one.)
(A) Increase
(B) Decrease
(C) Stays the same
(4) A model sailplane is flying with a steady horizontal speed
component of 30 ft./sec. It has a sink rate (downward speed) of
1 ft./sec. The weight of the model is 10 lb. Estimate the aerodynamic
drag.
________ lb.
(5) You are flying a Cirrus RC model over a contest field. Your
flight path is in a due north direction. Your true airspeed is 25
mph. The wind is westerly at 10 mph. Your ground speed is (circle
one):
(A) Greater than 25 mph
(B) Less than 25 mph
(C) 25 mph
(6) A Schweizer SGS 1-34 sailplane is sitting on a ramp. Its
wingspan is 15 meters and its weight is 800 lb. A one-half scale
model is sitting next to it. Every component in the model is exactly
scaled to one-half size from the same materials. For example, its
aluminum wing has a span of 7 1/2 meters. What is the weight of
the model? (Circle one.)
(A) 400 lb.
(B) 267 lb.
(C) 200 lb.
(D) 100 lb.
(E) none of these
(7) You are circling an Olympic 99 over a sod field on a still,
hot, sunny day. A large parking lot, which is half asphalt and half
concrete, is adjacent to the field. If you wish to climb at the
greatest rate, you should fly your plane (circle one):
(A) Over the asphalt
(B) Over the concrete
(C) Stay where you are
(8) A popular proportional RC system widely used today transmits
information to a model sailplane in the form of on-off pulses. This
type of system is called (circle one):
(A) Analog
(B) Digital
(C) Hybrid
(D) Erratic
(9) As the center of weight (CG) of a model is moved further and
further aft, its stability (circle one):
(A) Increases
(B) Decreases
(C) Stays the same
(10) You are flying a model which has both up and down aileron
control. You wish to roll the model from straight and level flight.
To do so, you move the ailerons so that the left wing goes down.
In which direction did the trailing edge of the aileron on the right
wing move? (Circle one.)
(A) Up
(B) Down
(C) Stayed the same
(D) Impossible maneuver
I managed to get a score of 10, but calculating
#4 was a real shot in the dark. Since I have not committed the formula
for aerodynamic drag to memory, I figured the quiz creator would
be kind and give only information necessary to answer the question.
Since the aerodynamic drag has units of pounds and the weight of
the sailplane is given in pounds, the multiplication (or division)
term must be unitless. There are two parameters provided with units
of feet/second, so in order to cancel units, it is necessary to
divide them (as opposed to adding or subtracting). I reasoned that
a better glide ratio indicates lower aerodynamic drag, so dividing
the model weight by the glide ratio (30:1 in this case) results
in a quotient that gets smaller as the glide ratio gets larger.
I did 10 lb / 30 = 1/3 lb. Voila!
Question 6 might need some explanation. Volume
is a cubic function of length, so scaling all the length dimensions
by a factor of 1/2 results in a volume scaling factor of (1/2)^3 = 1/8.
Since the same materials are used throughout, density (weight/volume)
is constant is the scaled-down model. To get the answer, multiply
800 * 1/8 = 100 lbs.
Answers to the other eight questions are pretty
straight-forward to anyone familiar with general flight physics.
- Kirt Blattenberger
Sailplane Quiz Answers
Here are the answers to the Sailplane Quiz which appeared in
last month's AAM (page 50). If you didn't take the quiz, don't peek
at the answers, but go back and try the questions. An 18-year-old,
Alan Druschitz, got nine out of ten correct. How did you fare?
Answers
(1) A
(2) B
(3) B
(4) 1/3
(5) B
(6) D
(7) A
(8) B
(9) B
(10) B
Posted August 23, 2014
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