PHOTO: SAM DIMAIO
The lines of the EU-1Awere well suited for the USAF Thunderbirds scheme, which was used on the original Project Pattern EU-1A, “Baby Huey”. Sam DiMaio acquired his EU-1A, pictured here, when it was 10 years old, in 1995! After a full restoration, Sam and his two sons estimate they have put 3,000 flights on the plane to date. Currently using a “vintage” Rossi 60 and Spring Air retracts with a JR 10X converted to 2.4 GHz.
of the architect of the noise and turnaround rule changes, none other than the legendary Ron Chidgey. At a time when many flying fields (domestically and abroad) were in- creasingly unable to support the large over- flight area and substantial noise footprint of Pattern, the decline of the event seemed im- minent. The implementation of noise limits and the turnaround style of flying certainly changed the character of the event, driving some designs and equipment into obsoles- cence, and some pilots to other events. How- ever, the changes also ensured the viability of the event for the future, and many (my- self included) credit Ron as a visionary. The turnaround style of flying spurred ma-
jor changes in airframe designs. To provide clear distinction between maneuvers, and al- low pilots time to make adjustments between maneuvers, a slower flight envelope was ben- eficial. Tail moments increased to provide stability at the lower speeds. Larger air- frames with higher drag profiles were devel- oped to make it easier to fly at slower speeds. The larger, draggier airframes flown at mod- erate speeds put an emphasis on midrange throttle response, torque, and pulling power to complete vertical maneuvers without the benefit of a running start. Attention was paid to lighter construction and finishing tech- niques; the once taboo of heat shrink cover- ings was forgiven in favor of lighter weight. Trike gear configurations were traded in for lighter tail dragger configurations. The old mantra “Speed is King” was dead,
being replaced by “Horsepower is God”. New generations of engines used lower port tim- ing to achieve a broader, flatter, torque curve that peaked at lower rpm (less noise). Long stroke designs became the norm, and the tuning length of pipes increased dra- matically, from approximately 13–14 inches (glow plug to tuning baffle) to 20–21 inches as rpm dropped from ~13,000 rpm to ~10,000 rpm. Props grew in both diameter and pitch, with 12–11 and 13–10 becoming common place. Detailed efforts were made to keep airframes quiet, such that the noise limit could be “filled” with usable horsepow- er. Engine soft mounts proliferated faster than mice in a deserted barn, intake filters were used to soften intake noise, metal spin- ners were lined with foam or replaced with plastic spinners, and rattling pushrods and hatches were padded with foam. Tighter cowling and fully enclosed pipes became more common to shield radiated noise. Of course, the long overlooked 1.2 ci 4C became a more viable option. With an in- herently fatter torque curve, better throttle response (than the piped 2C engines of the
FLYING MODELS
day), and lower noise output, several de- signers built planes tailored around the available “sport” 4Cs of the day—namely the OS 1.20FS and Enya 1.20R. Ron Chidgey’s Tar Baby, Tony Frackowiak’s Challenge II, and Tom Millers Reaction come to mind. At the 1987 WC in France, Gi- ichi Naruke debuted the YS 1.20 SF 4C in his Silent. From that point it was clear, the 4C had the potential to end the reign of the piped .60 2C. Towards the end of the 1980s, the majori-
ty of designs were for the piped .60 2C, which was nearing the pinnacle of its development. The most common designs included the Au- rora, Beetle, Conquest, Dash Five, Jekyll, Joker, LA-1, Summit, and Tipo (continually evolved by Dick Hanson Models). FAI ma- neuver sequences had little effect on the de- velopment of airframes through the 1990s, but AMA maneuver sequences gradually shifted to the turnaround style of flying with the introduction of “Expert Turnaround” (an interim class by design) in 1990, followed by full turnaround schedules for Masters and Advanced in 1992. The Sportsman class was partial turnaround in 1992, and became a full turnaround class in 2002. I’d fearlessly suggest that 1992 was the
tipping point between the piped .60 2C and the 1.20 4C. In 1992, my Dash Five was pow- ered by a substantially modified Webra 60 Race LS ABC with Dynamix slide valve car- buretor. With either a 13–13N or 13.5–11.5N, 30% nitro and the S&W carbon fiber pipe put the rpm right about 9,500. The more common OS “Hanno” .61 RF ran a 12–11 at ~10,500 rpm, or a 13–10 (for the more adventurous) at close to 10,000 rpm. OS was producing a supercharged (yes, a miniature roots supercharger) 1.20 4C, while YS utilized crankcase pressure to pressurized the intake on their 1.20. Both engines were comfortable swinging 13 and 14-inch props ~9,000 rpm and did so with an abundance of torque and smooth throttle response. Yep, once the 4C was developed for com-
petition, it was no surprise it made more power and noise when given a 2:1 displace- ment advantage. The “penalties” for using the 4Cs were added vibration, more noise, and weight—lots more weight. The typical 2C (bare) hit the scales at 20-21 ounces while the YS 1.20AC was 35 ounces and the OS 1.20 SP topped the scales at 36.3 ounces. Earlier mainstream 4C Pattern designs in- cluded the Desire, Dr. Jekyll, Elan, Miss Beetle, Python, SL1, Saphir, Silent ST, and Typhoon. Through the 1990s, the emphasis of the
maneuver schedules was on lines and geo- metric shapes. Form followed function, and aircraft designs grew increasingly longer tail moments. The longer tail moment was perhaps epitomized by the Dave Guerin de- signed Prophecy, one of several designs col- lectively deemed “yard darts”. The designs continued to slowly grow in size as the 1.20 4C setups were further developed and re- fined. For the first time in the history of Pat- tern, the weight limit was “in play”, and on more than one occasion, pilots changed to smaller wheels, prop nuts instead of spin- ners, and implemented other weight saving measures to remain under 11 pounds. As the 1.20 4C established dominance in
the 1990s, both FAI and AMA removed the engine displacement limit (~1996) in an ef- fort to increase engine diversity. The thought was that removing the displace- ment limit would allow larger displacement gasoline engines (cheaper, cheaper fuel) and “economy” large displacement sport glow en- gines to compete with the specialized and expensive 1.20 4Cs. Predictably, this never happened in numbers of consequence, as the most competitive setups setting the perfor- mance bar used powerplants with the great- est power to weight ratios. In an attempt to keep the aircraft size
from growing (a natural path, given more available power), dimensional restrictions of 2 meters for wingspan and fuselage length were put in place. The exact reason(s) for the choice of 2 meters has been the subject of many debates. Presumably, it was chosen as it was close to the maximum dimensions of the largest planes at the time, and perhaps it was chosen based on the standard height of doorframes. Following the unlimited displacement
rule, a number of Pattern specific large dis- placement engines were released. Among them were the OS 1.40 RX and Webra 1.45R 2C engines, both of which trumped the 1.20 4Cs in terms of increased power, lower weight, lower vibration, reduced fuel con- sumption, and lower noise levels. These en- gines were further refined with the OS 1.40 EFI (yes, electronic fuel injection) and the Webra 160 MC, further escalating the battle with YS 4Cs. The typical large 2C setup used props ranging from 17–13 to 18–10, running at 8,000 +/- a couple hundred rpm, and did so using 10–20% nitro fuel. The YS 4C variants of the day were running 15.5–12 to 16–13 props in the mid to high 8,000 rpm range, and required 20–30% nitro fuel to do so. A couple of notable aircraft surfaced in the
mid 1990s, including Peter Goldsmith’s Car- rera, first seen in the US at the 1996 Na- tionals. The Carrera used neatly installed fixed gear with wheel pants that was not only lighter (and more reliable), but wind tunnel testing showed it had less aerody- namic drag than the typical retract installa- tion without wheel well covers. The 1997 Dick Hanson EMC2 was also designed with fixed gear and perhaps more notable was the sheer size of the EMC2. The EMC2 was 78 inches in both length and wingspan, had 1,150 square inches of wing using a 2:1 dou- ble taper ratio, and a very tall fuselage that was 5.5 inches in width. The EMC2 was an excellent flying plane that was years ahead of its time, but likely never achieved the popularity of prior Hanson designs due to the perceived difficulties of providing it ad- equate power while staying under the 11- pound weight limit.
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