Hi Fly Twin Motor (oz15119)

About this Plan

Hi Fly (Twin motor). Installation plan for electric powerplant. Twin pusher layout.

Note this is not a plan to build a complete airframe. This is a supplement plan that shows how to fit twin electric motors onto the Graupner Hi-Fly (oz5111) RC glider.

Brushed motors, with 5:1 gearing. Folding props.

Direct submission to Outerzone.

Update 30/12/2025: Added intructions (in German), thanks to Martin Huebner.

Quote (google-translated): "General Information: It is important to carefully read the assembly instructions, the RC 73 installation instructions, and the EL 73 electric drive installation instructions before beginning construction.

The text on the EL 73 electric drive installation diagram must also be observed. Always use red wires, sockets, and plugs for connections to positive terminals (+) and black wires, sockets, and plugs for negative terminals (-).

Due to the relatively low power surplus of the electric drive, the Hl-FLY must be built with extreme care. The construction must be carried out without any warping. The basic structure must be sanded smooth. There must be no resistance, eg from unnecessarily exposed wires, etc. The flying weight should be kept as low as possible. To save weight, the model can be painted, as this will always increase its weight. Under certain circumstances, the airflow may be adversely affected by the paint edges.

Generally speaking, the model's climb rate improves with lower flying weight. Conversely, the higher the flying weight, the worse the climb rate. Therefore, it is essential to keep the weight as low as possible.

For the RC electric model aircraft, prior flying experience with a two-axis controlled model is required. Due to the high payload required for electric flight, it is crucial to prevent the model from entering unintended flight attitudes that could generate excessively high forces. Therefore, aerobatic maneuvers such as loops, spirals, turns, dives, etc., must be avoided. Further details regarding practical flight operations can be found at the end of the installation instructions.

Installation of the electric flight accessory kit in fuselage version A (see parts list 1)

The wires are soldered to the switch's solder lugs (A) as shown in diagram A. Strip the wires, tin them (see sketch), and cut them to the appropriate length.

ATTENTION! All connecting wires should only be as long as absolutely necessary. Despite the relatively large wire cross-section, a certain voltage drop occurs, which reduces performance. Stripped, tinned stranded wire is used for the short cross-connections of the switch tabs. To prevent confusion, the two wires leading to the sockets (K) on the fuselage are labeled with the enclosed labels. Now insert the switch into the switch holder (B), guide the labeled wires out to the correct side, and then slide the guide part (C) onto the switch knob. The cranked linkage (D) and the stops (E) with the screws (F) are mounted as shown in the drawing. Setting the distances X and Y is described in the section 'Adjusting the ON/OFF Position'.

To attach the 4-pin connector (G)-(G1), strip 3-4 mm of insulation from the ends of the two wires and tin them so that they can be inserted into the pins (GI) at the top..."

Update 29/9/2026: Added kit review from RCM&E March 1974, thanks to RFJ.

Supplementary file notes

Catalogue page.
Instructions (de).
Instructions parts list.
Review.

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