Compromises 

An aircraft is usually the result of a design process that is a compromise between the aircraft’s purpose, the available engine, the current level of aerodynamic knowledge and other factors. Over more than a century of aircraft development, the knowledge of aircraft designers has continually improved, and aircraft designs have naturally evolved with the level of technical knowledge at the time of their creation. I use the word “usually” because there have been highly unorthodox aircraft designs in which aerodynamics did not play a significant role. In these cases, the engine power prevailed.

Making a faithful scale model of an aeroplane isn’t also an easy engineering discipline. 

I understand   modellers who want their model to match the original as perfectly as possible. The problem is what exactly is an original. 

When my colleagues prepare a new aircraft kit, they ideally work with the original production documentation, good quality photographs and, for verification, a 3D scan of the actual machine. The historic aircraft we scan are carefully selected. In museums, we look for pieces in as historically faithful a condition as possible.  For instance, concerning the L-13 Blaník glider that we’re going to make in 1/48 scale, it’s quite easy, we just drive the scanner to our nearby airport.  

However sometimes museums’ aircraft need some repairs or are missing parts. And in some cases, the newly fitted parts aren’t exact replacements of the original parts. Of course, we don't want to include something like that in a 3D design. This is not to suggest that museum technicians have done a bad job. They are often in a difficult situation because original parts are scarce and documentation for a given part of the aircraft might be missing, and the complicated curved shape of any specific part is sometimes hard to deduce from historical photographs. 

We are also in the same difficult situation if the production documentation or the aircraft in its original condition is not available or is only available in partial form. In this case we study historical photographs, wreckage images, surviving aircraft parts and drawings prepared by aviation researchers. The result is our best interpretation, which is based on the current state of knowledge.

This is a demanding discipline. The quality of the documents, including publication drawings, changes over time. If someone was preparing a kit for a particular aircraft, say, thirty years ago, they had different documentation than we would have in our hands today while working on said aircraft. And in another ten or twenty years, knowledge of the type will probably be a little more improved. 

It is therefore important to approach kits produced in the past with a certain tolerance and detachment. They can usually be used to build a beautiful model. Last week I saw a very nicely built ARII 1/48 Ki-61 Tony. This kit was produced in 1972 and has a beautifully riveted surface. Some of my favourite pieces from this period include the Ki-43 or Ki-45 from Nichimo. In the half century since their creation, new information about these aircraft has probably come to light and today the designers of these kits would possibly design some parts in a different way. But I don't think that's important. They are just beautiful pieces.

But it’s a bit of a digression from my consideration of the progression of knowledge over time. I would like to mention the relativity of the validity of the research materials. They often contradict each other to some extent. The production documentation may not correspond exactly to the condition in which the aircraft left the factory. The point is that there may have been changes during the manufacturing process. Manufacturing jigs may have been modified, some details of the aircraft may have been changed and the original documentation no longer reflects the production details. Even a 3D scan of an aircraft that is preserved in its original state may not be completely accurate. If it is an aircraft that has been in service for a long time, it has usually been through a lot. I'm thinking of hard landings, small accidents or even crashes and subsequent repairs. The plane is not made of diamond, but of metal, possibly even wood and canvas. A hard landing can cause deformations, for instance the rear half of the fuselage to be moved up a few degrees from the longitudinal axis of the machine. Nothing special for the pilot. An extra worry for the kit designer. 

So, even with ideal research materials for kit design, there are situations where they contradict each other. So ,a kit at a certain scale is not only a scaled down version, but almost always the result of various compromises. If we have to make them, we try to make them as best as we can. 

As colleagues from previous generations did before us and, hopefully, as some others from the next generation will do after us. 

Jan Bobek