CR42 Major Restoration Program

Once again our expertise and craftsmanship was called upon by the Imperial War Museum at Duxford. This time a complete new inner and outer engine cowling was to be reproduced for the Fiat CR.42 Falco, but as in most restoration projects we are presented with battered fragments of component parts, possibly along with faded drawings with various dimensions advised, but going no where to indicate an actual dimension. Our contact at Duxford outlines as to what he requires us to manufacture; inner and outer cowls, angled butt straps and angular fuselage support frames are all required.

 

Our first reaction is to lay out full size the components that are to be manufactured from this initial plan. An idea of tooling costs and material sizes can now be ascertained. With any project such as this we have to work and propare our quotation on an elastic basis as it is virtually impossible to foresee all the problems and pitfalls that lay ahead. What makes this project more difficult is that the units have to be manufactured from aerospace materials, as they have to pass and qualify for an airworthiness certificate.

 

After establishing the types of tooling required, drawings are prepared for the machinist to work to. The appropriate materials are sourced from California USA as a company there carries large size sheets in stock of aviation materials. Here again, we have to employ the use of a cad-cam system to try and establish the various profiles that we need to obtain so the machinist can turn the tooling to the correct sizes required.

 

Working on a cowling that is 1.2 metre in diameter and approximately 400mm deep, one cannot allow for too many misjudgements, as each one could be extremely costly, especially when you are looking at tooling costing in excess of £10,000.

 

During the manufacturing of these components all the various items produced come up for heat treatment operations, that again can cause difficulties as you need an oven that will accept 1.5 metres. Throughout the entire manufacturing program difficulties do present themselves and are duly overcome one way or the other. Slowly and gradually progress is made. Finally, we reach the stage where all the components are made but now they have to be mated and matched together so that when the air frame fitters come to put their rivets into the two adjoining skins, they have a perfect fit to work with.

 

In addition to the main cowl, we also designed and manufactured all the tooling for the spinner nose cone, which was also a very intricate component to manufacture as it had to have a stainless steel wire rolled into it's outer edge. (See picture Spinner Nose Cone on right)

 

As can be seen from the various photo's, Metspin's Vintage and Historical Aircraft cell have once again triumphed in being completely successful in the entire manufacturing of the complete engine cowling assembly. Many hours have been consumed on this project. It is without a doubt that this is an excellent example of supreme craftsmanship at it's best. It has to be appreciated by all that these items have been hand sculptured by experienced craftsmen at the peak of thier trade. Only can this type of work be entrusted to craftsmen with such a high level of skill.

 

Here at Metspin Ltd, Quality craftsmanship still lives on.

 

Technical Information:

Full size plans developed first and then computer imaged for detail. All main form tooling, including split section form tooling manufactured in steel. The remaining pre-form tooling was manufactured in MDF. All pre-forms are spun on MDF to maintain wall thickness. At each of the five pre-forms the components were fully vacuum annealed and then re-spun to the next stage. When finally spun, both inner and outer profiles were uniform matched and inspected for shop floor fitter assembly, ready for riveting together.

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