October 1974 American Aircraft ModelerTable of Contents
Some things never grow old. These pages from vintage modeling magazines like American Aircraft Modeler, American Modeler, Air Trails, Flying Aces, Flying Models, Model Airplane News, & Young Men captured the era. I will be glad to scan articles for you. All copyrights are hereby acknowledged.
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
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)
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.)
(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.
(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):
(9) As the center of weight (CG) of a model is moved further and further aft, its stability (circle one):
(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.)
(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?
Posted August 23, 2014