UPDATE NOTES FOR THE 1957 "HOW TO STUNT" ARTICLES PUBLISHED IN MODEL AIRPLANE NEWS, BY W. F. (WILDBILL) NETZEBAND
By 1956 the stunt event and rules were 10 years old, and about to end their growing pains. In 1957 the GMA pattern became official, and all of the modern maneuvers were now on the table. Up through 1956 rules changes were mostly additions of more difficult maneuvers, with some shuffling in the order, and more "text" to try to explain how they should "look". Up through 1954 the appearance points were almost 20% of the best total score. This effectively accelerated the trend to high finishes and "style". Highly detailed cockpits were in vogue, along with lots of detail lines, tiny lettering, and fancy noses. The need for coupled wing flaps aggravated the design problems created by the increasing weight, since the output level of power trains remained stable. The ubiquitous Fox 35 twisting a 10-6 prop was the hot set up. There were folks who were nibbling at more power and different geometry, but they weren't raising the average performance level.
I was having good competition results with the "GOLD BRICK", but was enjoying the performance of my HALF FAST IV. I enlarged the HF III by 50%, and it was a real kick to blaze around the pattern behind a Fox 35! It had some "bad" habits, which I sort of fixed as the "FIERCE ARROW" design data took shape. Meanwhile, I was on a roll with math, and a couple of good books. So, I put together the 5 articles of interest here.
On the whole, none of the information printed would result in anyone coming up with a design that wouldn't fly well. I can say that with confidence, since the rest of my career in stunt was trying to get folks to measure the flight path during an official flight. I apologize for publishing the erroneous treatment of the wing and the flaps. I parroted the conventional modeler's wisdom that one started with a plain wing, and then "added" flaps to the trailing edge, BUT, the wing area I used in calculations was the area WITHOUT flaps. WRONG, Bingo! The proper treatment takes the total area contained inside the outline as the WING AREA. Flaps calculations are based on the flap chord to wing chord. Increasing the flap chord ratio increases the power of the flap to add lift without changing angle of attack. Since a wing with deflected flap can still increase its angle of attack, the total action becomes non-linear, and the math gets hairy. The increased drag requires that the power train come up with quite a bit more torque (thrust) than used in level flight.
I was a little bit optimistic about correcting lateral warps by twisting the flaps. This has been proved to be a NO-NO, except if the flaps are not parallel to each other in the first place. Remember that the pattern I published was current in 1956, when the articles were completed and sent to the publisher. The tricks to use the wind to help your pattern are pretty much out date now, since we have sharper judges and better power trains. Back then, we had to do a lot of creative whipping and placement to get all of the way to the landing.
I am embarrassed by my naïve thoughts about the 5 foot corner. I believed it was happening, but was fooled by the pitch axis illusion we uncovered much later in history. Since I couldn't get the numbers to make it happen, I hypothesized the ZOOM theory. While nature allows the ZOOM to happen, our planes and power trains won't let us exit the corner without losing too much velocity (energy). Current equipment with the double-size power plants now do better corners by increasing the energy available. (Sadly, the 5 foot radius path of the airplane's CG during a competition-level stunt pattern is still waiting in the wings)! I am disappointed that the establishment has consistently elected to leave the number (5) in the rules book.
The discussions on line angles was rudimentary, and not defined by accurate calculation until my 1966 "Painless" articles. (Also in Dave's inventory). Luckily, having the lines exit aft of the CG is generally safe. The 3% offset of the fuselage on the wing was derived from designs of the day. 40 years later we determined that we don't need that much, and it can be detrimental if too excessive.
I'm happy Dave offered to reproduce these articles. We've come a long way, technically, and have maintained a high level of artistry in our designs. I had a chance to go back there and open a few memory banks. It was a beginning of a new direction in my path through the CL hobby, and I am pretty sure that if I hadn't gotten involved with the digging up HOW and HOW MUCH information for CL planes, I might have wandered into other interests. It is still fun, even though I have become hypoactive in the competition circles.
Wild Bill.
December 1956 Model Airplane News - How to Test a Stunt Ship.
January 1957 Model Airplane News - How to Fly STUNT.
February 1957 Model Airplane News - Theory and the Stunt Model.
March 1957 Model Airplane News - MORE..about Stunt Theory.
April 1957 Model Airplane News - Pointers On Stunt.
Also on this site are the following articles by Wild Bill.
1963 American Modeler Annual - How to select the proper glow plug.
July/August 1966 American Modeler - Control-Line Aerodynamics Made Painless.
September/October 1966 American Modeler - Control-Line Aerodynamics Made Painless - THE CONTROL SYSTEM.
December 1967 American Modeler - Control-Line Aerodynamics Made Painless.
