Scale Modelling

The aim of scale modelling is to build a model that looks and flies like the real aircraft. This is a simple statement but it covers a vast spectrum of individual modellers' aspirations.

At one end are those who are quite content to build a model that is recognisable and fly it at the club field on occasional weekends. These modellers now even have a rapidly increasing range of good looking Almost Ready to Fly (ARF) models to purchase if their building skills are limited. At the other end of the scale are those who are on the never ending quest to build the perfect model, down to the finest detail (the proverbial 'rivet counters') and fly at the highest level competition available. Wherever a modeller wishes to end up on the spectrum, he (or she) should start at a level that is appropriate to his current flying skill level.

While some scale models are difficult to fly, there are many scale models that are no more difficult to fly than a basic trainer. Models such as the good old Piper Cub even look like a trainer, but can also be built to a standard sufficient to fly at World Championships. As the modeller becomes proficient with this type of model he will usually want to graduate to more complex, difficult and more satisfying models . How many of us wanted to build a Spitfire as our first R/C model?
 

Fortunately most of us were persuaded to build a trainer and learn to fly first. Unfortunately, many modellers then fell pray to the myths surrounding scale models that they are hard to fly, hard to build and expensive. In fact, building scale models is one of the most cost effective aspects of modelling. Leaving aside the motor and radio, most scale models would have less than $200 worth of materials in the structure. ARFs are more expensive.

 

Finally a word about competitions. Another of the myths of scale modelling is that competitions are high pressure events and dangerous for models. Nothing could be further from the truth. In a scale competition your's is the only model in the sky (how often does that happen?), the manoeuvres are not difficult and other modellers are very supportive, particularly of beginners. The main skills to be learned are to fly the model smoothly and do the manoeuvres in the right place. Once learned these skills shine through even in general club level flying and it is easy to pick the competition flyers.

In Victoria, the Victorian Flying Scale Aircraft Association conducts a series of competitions (known as Fun Scale) and rallies aimed at the beginner. These are very low key, have no static judging or builder of the model requirement, and concentrate on realistic flying. Look in the VMAA site (here).

As an example of a scale model, let me introduce you to my CA25 - Winjeel.

This Model was built from the outset with the aim of taking it to the Scale World Championships. Consequently, everything had to be just right. I spent many months trying to obtain accurate drawings of the aircraft, finally coming to the conclusion that there were none available. Finally I was able to get access to the historical archives of Hawker De Havilland (who had inherited all CAC material) and was given the Master Dimensions File (MDF) for theWinjeel. This consisted of the X-Y coordinates, to 1/1000 inch, of every piece of the full size aircraft.
 

I was then able to type the numbers into my ModelCad program and draw all the fuselage, cowl and canopy sections, and wing, tail and fin ribs to the scale I selected, 1:5.25. This information was used to make a fully detailed mold for fuselage and cowl (and also various fillets and fairings) and to construct conventional built up wings and tail.

Another piece of invaluable information from the MDF was the geometry of all hinges, some of which were quite complex. A feature of the Winjeel is the very large cockpit area and it was apparent from the start that I would have to detail the interior fully. I finally decided that the best way to duplicate the internal structure was to vacuum form most of the components. So I had to build a vacuum former and learn to use it! This was actually very rewarding. I had laid up several fuselages before selecting the final one.

Half way through the project, I became worried about the scale incidence on the tailplane because it was most un-model - like. So I used one of the discarded fuselage molds, knocked up some foam wings and tail and built a test model. I need not have worried about the incidence because the test model lifted off straight and gentle with absolutely no trim changes required. The big benefit was that I now had a practice model which matched the final model in almost all flying characteristics. I was therefore able to do nearly all my practising without fear of damaging the good model.

The model has now been to two world championships, most recently in Canada where it finished 9th in static and 15 th overall. Clearly the model is better than its owner! The sad news is that it was effectively written off at the recent Nationals in Albury but still came second. The good news is that all the many many molds and forms are just waiting for me to rebuild.

As a further example of scale building, read the background and story on Colin Kahn's Lancaster (here).

Noel Whitehead

(Click on photos for enlargement - 640 x 480)

*** 10 January, 2010 10:27 PM +1000 ***

Last updated 10 January, 2010

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