Electric Challenge Twin (oz7334)

About this Plan

Electric Challenge Twin. Radio control electric powered twin sport model.

Quote: "Thoughts of a twin electric plane had been running around in my head for quite some time then one day while reading Bob Kopski's column, I came across a reference to Dr Keith Shaw's article published in another magazine regarding the twin theme. This was just the stimulus needed to get the grey matter cooking and start the design process, the development of Electric Challenge - The Twin was under way.

My first thoughts were about the motor power. I have a good selection of Astro Flight cobalts ranging from 15's to 60's, so this was not really a problem and the 15 geared cobalts were finally settled upon. A lot of thought was given as whether to have the props contra-rotate or not. Keith Shaw states in his article that there was 'very little change in performance' between the two options. I decided to go with the contra option. I do have memories of the old WWII warbirds using the contra principle, so I guess that's where it comes from.

Now that the power was decided, a design had to be created based on the guidelines utilizing Keith's formulas and two that have been around for long time. T-L-A-R, That Looks About Right, and K-I-L-S, Keep It Light Stupid. The effort was expended, and the model presented here is the result.

Next question, what batteries to use? I chose the Sanyo 1250 mAh SCR's because of their size, weight, and ability to deliver the punch necessary to get the craft airborne.

Many sketches were made in an attempt to catch an attractive and simple presentation. The lines of my previous design, the Electric Challenge 25 (oz7100) seems to have won. Most of the construction follows this design.

Construction. When starting to build a scratch design, I always make a kit of the parts necessary to build the complete plane. Templates are made of all formers..."

Supplementary file notes

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