Control Line: Aerobatics
LAST month we flew the new airplane in level flight to examine the characteristics of a high, or low, outboard wing; we also watched inverted flight, inside and outside round loops, the inside square, the gliding traits after the engine cuts, and the landing features. After observing these items, you should get a very good idea of whether this new plane is going to fly pretty good or be a fixture on the wall. Keep in mind the variables that you have to work with, and there are quite a number: tip weight, nose weight, tail weight, engine offset, prop selection, engine shims, leadout variance, flying-line length and handle adjustment. More drastic moves involve tweaking the flaps, cutting on the flaps, cutting on the elevators, changing the flap horn alignment by cutting into the fuselage, changing the landing gear, or bending the initial L.G. wires.
Control Line: Aerobatics
DESPITE a lengthy two-month series on trimming, there are a couple of other related items we should touch on. First off, let's look at engine speed and lap times. If you have to run your engine at a fast two-cycle on the ground to get the plane to complete the pattern, then you are probably in need of some engine rework. Those who use tachometers usually set their engines in the 8000-rpm range on the ground. If you have to set the engine much faster on the ground, you will no doubt experience some sagging by the engine in the difficult maneuvers. For instance, on 60/62-foot lines, a 5-second lap is pretty fast and probably means that the engine is two cycling most of the time. If your lap times are 5.6 to 6.0, then the engine is probably running a little rich and you may not have power in the maneuvers, unless you have a very powerful engine. All this is assuming that you are running an 11- or 12- inch prop with 5 to 7 pitch.
Control Line: Aerobatics
SOME more suggestions on the Max 40 FSR. According to two-time World Champ Bill Werwage, after several gallons of testing in the spring and summer, it seems that with conventional props (i.e. 12-6, cut down 13-5, etc.) the Max may work better on a large airplane (i.e. 675 sq. in. and over) that weighs in the 58 oz. area and over. According to Bill, this taxes the engine's power and helps to tame it down. Unfortunately, at the time of this writing, some top fliers have abandoned the Max for this summer in favor of the old reliable ST 46; for instance Whitely, Les McDonald, Fancher, Werwage, Jim Armour and Dave Hemstrought. However, Dave Hemstrought has some additional comments on the Max. He and Stan Powell were using Max in the spring and came up with two bits of modification that seemed to help. Firstly, they used an .005 in. head gasket to lower the compression. Secondly, they very carefully took the glaze off the chromed cylinder liner with an automobile brake cylinder hone by hand. This allowed the ring to seat better in the liner with the result that the engine did not tend to run away in the round maneuvers, the most common problem among users of this engine.
AMA Nats Lincoln '79: CL Aerobatics
"HAIL, Hail, the gang's all here!" You bet they were: four World Champions, eight former National Champions. Overheard many times during the week was the exclamation, "This has got to be the greatest stunt contest ever held." It may well have been just that. And when the wind finally calmed down at about 2:00 a.m. Sunday morning, the "Old Bear" from Irving, Texas, Bob Gieseke, had the Walker Cup sitting in his motel room for the fifth time. Bob won this Nationals to add to his titles in 1966, '68, '74 and '75. Stunt fliers had been hearing for months that Lincoln would be hot and windy. This prophecy proved true for the 49 open fliers that turned out for the PAMPA revised format. Except for Wednesday's qualifying and Friday's semi-finals, which were near perfect flying days, the rest of the competition days were windy and Saturday's finals were flown in near gale winds. The Junior-Senior fliers did not enjoy good weather as 10-15 mph winds prevailed on Tuesday, the first day of competition; such a resounding disappointment (three juniors and six seniors) that both age divisions were flown on the same circle.
Control Line: Aerobatics
TWO stunt fliers have gained moderate notoriety lately by using homemade three-bladed props. Bob Hunt won the 1978 World Championships using his own three-blader made from Rev-Up 12-5 blades; he also competed and finished sixth in the 1979 Nationals with this type of prop. Gene Martine also made up several three-bladed props to use with his HP-40s and Max 40s. What I want to stress is that both of these men are excellent machinists with thousands of dollars worth of machine tools at their disposal; Bob's father, Jim, is a machinist and small parts producer by trade: Gene is a machine shop teacher in a school and possesses exceptional skills. The average stunt flier should not attempt to put together a three-bladed prop. Considerable skill and safety consciousness is required to machine the front and backplates for a homemade three-blade prop. The fitting of the three blades together and the balancing of the prop is very exacting. It is my opinion that there are only a few other qualified persons in the United States who could successfully and safely construct a three-bladed prop.
