Pacemaker (oz199)

About this Plan

Pacemaker. Rubber cabin model. Twin rudder design.

The Pacemaker design was originally kitted in 1940. This here is a later redrawn plan from Model Builder, and is marked: 'Traced by E Linn 1990'.

Update 25/02/2014: Replaced this plan with a clearer copy, correctly scaled, thanks to theshadow.

Quote: "Classic OT rubber at its finest! Properly built, this 1940 twin-fin cabin job can be very competitive in SAM Commercial Rubber and Small Rubber Fuselage events.

In the late 1930s Wichita, Kansas was a hotbed of modeling activity, spurred on by the full-scale aircraft Iindustry which was just recovering from the throes of the Great Depression. During that time, RJ (Bob) Youngman, a talented model designer in his own right, was a modelers best friend. Bob ran the model supply shop for one of two Orrs Department Stores, which were located strategically within the city. Both of Orr's stores stocked modeling supplies because full-scale and modeling activities were growing at an accelerated pace, However, the location of the College Hill store just across from East High School, guaranteed a steady supply of modeling customers during noon hours and after school.

Bob designed his first kit model, the J-Hawk, in 1938. Subsequently, Orr's sponsored a one-design contest for models built from the kit. In 1939 Bob produced his second kit model, the Chieftain, and again, no strangers to promotion, Orrs featured it in another one-design contest. By all standards, the Chieftain was an improvement over the J-Hawk. It was larger, flew better and as a consequence, the annual contest grew - both in entrants and in prizes.

In 1940 Bob produced his third and best rubber model kit, the Pacemaker. Much cleaner and more visually attractive than either the J-Hawk or the Chieftain, the Pacemaker featured elliptical flying surfaces with a V-dihedral wing and stabilizer. Although it was much more complex than either of the first two designs, the modeling youth of Wichita by now looked forward to the annual one-design contest and Snapped up the kits as fast as they were produced.

Dean Zongker, a local modeler, had been chosen to build all of the test models for the series. As a friend of Dean's, and a participant in the first two contests, Ernie Linn was involved in the flight testing of the Pacemaker. Unlike the first two designs, which were literally off-the-board fliers, this newest effort from Youngman seemed to be prone to a tail-heavy condition which showed up as a stalling tendency in the glide. To correct that condition, Dean and Ernie decided to move the cabin structure aft 3/8 of an inch, rake the windshield back more sharply to match the new angle created, and increase the lifting horizontal stabilizer area from about 30 percent to 39 percent of the wing area. These corrections fixed the problem and the model performed flawlessly after that.

The pacemaker's classic lines make it a very attractive ship to build. At the same time, because of its numerous compound curves and relatively complex structure, it is not a good ship for the beginning builder to tackle. However, for the more experienced builder and serious competitor, it has a great deal to recommend it. First, it satisfies the SAM 'Commercial Rubber' event. It is within the maximum wingspan specified and has a large 14-inch freewheeling prop. Most Commercial models have a prop diameter no larger than 1/3 of the model's wingspan, or more in the neighbourhood of 11 to 12 inches. Likewise, it satisfies the FAC 'Old Time Rubber' event because it meets the maximum 36-inch allowable wingspan rule. And again, that big freewheeling prop offers the same distinct advantages in FAC flying as il does in the SAM event. As a bonus feature, the performance of the Pacemaker is good enough to fly it in SAM 'Small Rubber Fuselage' events against larger designs.

BUILDING NOTES: The fuselage presents the most challenging aspect of the model. The longerons must be matched for equal flexibility to keep the sides from warping disproportionately. After the basic box structure is put together squarely, as noted in the perspective drawing shown on the plan, the nose and underbelly formers can be added..."

Supplementary file notes

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