R/CAerobatics F
or the long-time FM subscribers, “Project XXXX” has become a rec- ognized phrase that holds the promise of depth and details be-
yond topical discussion. Aerobatic enthusi- asts will no doubt recall the literary odyssey of “Project Pattern” written by former FM Editor Bob Hunt and former FMcolumnist Dean Pappas. From May 1984 to May 1985, Project Pattern thoroughly detailed the con- struction, finishing, and radio installation of an EU-1A (“Baby Huey”). After a brief respite, the series resumed with trimming articles from January to September, 1986. This month and next we’ll present the last 25 years of Pattern history—a prelude to “Project Pattern Redux”. Current day, the Pattern world is a very different place than it was in 1985. In truth, the world of Pattern was in a major state of transition in 1985, and the EU1-A, which ar- guably was at the pinnacle of Pattern devel- opment, was also obsoleted virtually over - night. For many years, both the Federation Aeronautique Internationale (FAI), govern- ing international Pattern competition (des- ignated F3A), and the Academy of Model Aeronautics (AMA), governing Pattern com- petition in the US, have maintained similar rules structures for the Pattern event. The two key influences on Pattern aircraft de- sign were the restrictions placed on the air- craft, and the maneuver schedules being flown. In the early 1980s, FAI limited aircraft
weight to 5000 grams (11.023 pounds) with the AMA limit at 11 pounds (15 pounds pri- or to 1980 for AMA). FAI additionally re- stricted the projected area of the aircraft to a maximum of 2,325 square inches. Howev- er, the aforementioned restrictions factored little, if any, in aircraft design. The most meaningful restriction was the engine size limit that was shared by FAI and AMA. Maximum allowable displacement was 0.6102 cubic inches (ci; 10cc) with an al- lowance for twin propped planes of 0.8060 cubic inches (13cc). Four cycle (4C) engines were also given an allowance of up to 1.0–1.2 ci, depending on the year. For many years, Pattern flying consisted
of unlinked singular maneuvers performed at “centerstage”; i.e., all maneuvers had a defined center that was ideally placed di- rectly in front of the pilot (and judges) to achieve maximum score. Between maneu- vers, a turnaround of the pilot’s choice was completed, which was commonly a ½ Re- verse Cuban Eight. The typical ½ Reverse Cuban Eight was flown nearly to the limits of eyesight, with a near full throttle dive on the backside such that the upcoming ma- neuver could be entered from a well estab- lished straight line at maximum velocity. Yes, back in the day, “Speed is King” was the mantra, and Pattern planes generated a substantial noise “footprint” beyond the boundaries of the typical flying field. The early 1980s were dominated by de- signs like the Arrow, Magic, Citation, and
64 PHOTO: CHRIS MCMILLIN
The Las Vegas “Circus Circus” casino hobby shop exclusively imported several brands (including JR) in the 1980s and provided a theme for a number of Pattern airplanes of the era like this nicely done EU-1A.
Tipo. Virtually all planes used tri-gear re- tracts and tuned pipes, and weighed be- tween 8 and 10 pounds. 57-inch fuselage lengths with 65-inch wingspans and about 750 square inches were the norm. Power- plants were piped 60 ci 2-cycle (2C) engines running 10.5–7 to 11–9 props, spinning 13,500–15,000 rpm on the ground, unload- ing around an additional 2,000 rpm in the air. OPS OS, Rossi, SuperTigre, Webra and YS all produced competitive engines. De- spite the displacement advantage, 4C en- gines were not used as competition varieties had not yet been developed. For the 1981 and 1983 F3A World Cham- pionships (WCs), competitors were allowed to “build” a personalized sequence from a master list of maneuvers. A similar system was used for the AMA Masters class from 1980 to 1989. The ability to customize a ma- neuver schedule also allowed/encouraged the development of airplane designs tailored for specific maneuvers. The EU-1A exploit- ed this opportunity by being the biggest (most visible) plane at the field with excep- tional rolling abilities (large fuselage and delta wing). The typical EU-1A measured 67 inches long with a 58-inch delta planform wing packing a whopping 1,000 square inch- es. Rarely did an EU-1A hit the scales at less than 10 pounds. Baby Huey used a heavily modified YS 60FR to spin a DW 11–9 at close to 14,000 rpm. The first of several major rule changes
came into effect at the 1983 WCs, which were held in Pensacola, Florida. For the first time, the FAI implemented a noise limit (to reduce the noise footprint) of 105 decibels at a distance of 1 meter. To avoid exceeding the noise limit, prop sizes increased to limit rpm, and power produced dropped substan- tially, proportionately compromising the competitiveness of larger (and heavier) planes. As the engine, prop, and pipe tech-
nology evolved, the FAI noise rule was ad- justed several times, ultimately to the cur- rent day limit of 94 dB at a distance of 3 me- ters. AMA followed suit with a noise rule of 98 dB at 3 meters in 1992, and then in 1994 dropped the limit to 96 dB at 3 meters. The implementation of the noise rules spurred a number of changes to the equip- ment setups of the time. The initial changes were the use of smaller diameter 3-bladed props (to reduce noise generated by prop tip speed), larger props to reduce rpm (reducing exhaust noise), and longer pipe lengths to reduce the rpm at which peak power oc- curred. Rpm dropped from 14,000+ to under 13,000. Higher pitched props from DW, Max Dailey, MK, and Asano were highly prized commodities. The 1983 Australian Team used soft mounted engines to reduce vibra- tion noise radiated from the airframe. The airframes also started to evolve; lighter, to fly better at lower speeds, and aerodynami- cally cleaner for more efficient use of the available power. The next major rule change came into ef-
fect at the 1985 WC in the Netherlands. At previous WCs, maneuvers were required to be presented in a box or maneuvering zone centered on the pilot/judges. The box was de- fined by the projection of 45-degree lines to the left and right of the pilot. For the 1985 WC, the style of flying was completely changed. The prior style of prescribed center maneuvers with un-judged turnarounds of the pilot’s option was replaced by a full “turnaround” Pattern. The box was in- creased to 60 degrees to each side (and a 60- degree top), and a full sequence of continu- ously linked center and turnaround maneuvers were prescribed. The primary motivation for the change in style was fur- ther reduction of the noise footprint. Even a cursory review of Pattern history would be remiss without acknowledgement
MARCH 2012
by dave lockhart You can reach Dave Lockhart via e-mail at
davel322@comcast.net
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