Ohm-Y-Gosh (oz14848)

About this Plan

Ohm-Y-Gosh. Radio control racer model. For electric power with Leisure LT-50 motor. Wing area 293 sq in.

Direct submission to Outerzone.

Quote: "Here is a popular 05 electric racer and fun plane that has really taken off in the Pacific North-west. It has a 300 sq in wing area and a very fast 15 oz wing loading. Why not start a one-design race in your area? Ohm-Y-Gosh, by Dave Katagiri.

Ohm-Y-Gosh is an electric powered, two-channel sport racer and intermediate aileron-elevator acrobatic flyer. The clever name for the model was a contribution from Avis Cawley, wife of Bernard Cawley, of the Boeing 'Hawks' RJC club.

The model began as a simple test vehicle on which to experiment with the second generation '05' electric flight systems. The design also satisfied two other objectives: one was todevelop a new club event (not that wedon't have enough already), and the other was to have an acrobatic sport flyer that could be used in several local fields where engine noise would otherwise prevent their use.

Ohm-Y-Gosh is sized for the 05 flight systems that employ six or seven 1.2 amp-hour cells. Leisure Electronics offers the 601 (Pattern) and 602 (Competition) flight systems. Astro Flight has its 05XL system as well as the new Challenger (cobalt) 05 system. None of these systems includes a safety fuse which is highly recommended. Four fuses were blown by the author while logging 70 flights which certainly saved a motor or prevented a fire in each case. A 20 amp fuse was used satisfactorily for all systems except the 05 cobalt on seven cells which required a 25 amp fuse. The Cox 6-4 grey plastic prop performed the best with these systems.

Several prototypes were made by local flyers which were powered with the Leisure Competition system using six cells. Flight duration with this system is about five minutes of high perfor-mance flight. As an audible loss in rpm begins, the motor should be shut off. The Pattern wind motor will Fun a couple of minutes longer, but with less performance.

A switch-off with down elevator proved simple and adequate. A roller coaster maneuver consisting of a pitch-up followed by a quick full down will shut the motor off.

The Ohm-Y-Gosh design is based on a wing of 300 square inches to set the wing loading at 15 ounces per square foot. At this loading, the gliding performance is similar to that of a 200 square inch 1/2A model. Where it differs from the latter is in power loading, Its performance is short of its glow engine counterpart; however, Ohm-Y-Gosh will cruise at 58 mph when powered with the Leisure Competition flight system (six-cell), This is a very respectable speed considering that it is an average two-way level entry speed trap measurement. Obviously, a diving entry technique would make a more impressive figure, but it would not calibrate the aircraft.

Locally adopted race rules favored a six-cell pack as it was a stock configura-tion. The race course layout was the AMA (provisional) 1/2A, 300-foot triangle with a 60-foot base between pylons two and three. Winning times were just above two minutes for a 10-lap race. further refinement should see times under two minutes. A constant chord wing of 295 square inches was set as a minimum wing area in the spirit of 'sport' racing, just as 'Q-500' and its constraints have set standards for that class. Stability of rules for any race class seems to be a must for longevity of that class.

WING CONSTRUCTION: The wing features a fully sheeting upper surface to maintain its shape, and is made full span using 36 inch long stock. Full span ailerons may be simpler, but for lighter weight, the plans show inset, conventional ailerons.

The suggested sequence of assembly is to glue the ribs to the leading edge, bottom spar, and bottom sheet at the trailing edge over the plan. Glue the top spar and shear webs.

At this point, the structure can be removed, and the bottom sheet forward of the spar and rib cap strips may be glued in place. Reattach the wing to the plan using shims to align the trailing edge to prevent warping. Install short filler spar sections between ribs to form the aileron spars, and add scrap filler reinforcement at the hold-down bolts.

Notch the ribs on top where the aileron torque tubes pass through, and relieve the aileron spars for the hinges. Note the off-center location of the input arms of the torque rod. Keep the inboard end of the torque rods snug to prevent aileron lash and possible flutter.

Attach the leading edge sheet from the leading edge to the top spar. The wing will now be stiff enough to be removed from the board to finish aileron torque rod installation. Don't glue the torque rod at the aileron end yet. Mark the bottom sheet with a pin by poking holes through the sheet from the top side. Mark the aileron outline on the bottom surface using a straight edge to connect the pin holes. Don't cut out the aileron yet.

Position the torque rods and finish gluing the back half of the top sheeting and the trailing edge strip..."

Supplementary file notes

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