scratch wings

My method differs in one major respect from the original; plastic is substituted for the wooden core. Although balsa is easier to work than plastic I believe this substitution offers several advantages.

The need for priming is dispensed with. This is always a messy, tedious, and time consuming process. Disaster results if a balsa wing core is not properly primed. No problem with plastic.
Plastic cement is not suitable for a composite wing structure and adhesives must be used. With the all plastic method modelers are free to use thier favourite liquid cement.
An all plastic scratchbuilt wing can be treated just as would a kit wing. Sanding and refining trailing edges, cutting out control surfaces, or drilling location holes for struts, present far fewer problems.

Cutting the blank for a plastic wing core couldn't be simpler. The thickness of plastic card selected will depend on the subject to be modelled, but 40 thou siuts most small fighter types. The blank should be cut just a milimetre or two under size in span and cord and not the 1/8" all round often recommended for wooden cores. The next task is to give the blank something resembling an airfoil section and this should be done before removing any center section cut out. Scrape and sand sand away excess material until the thinnest possible trailing edge is achieved. Don't worry if it seems a little fragile, this method allows for that, but do ensure an accute angle from about mid-cord to trailing edge. The leading edge is less demanding and needs only to be rounded off and slightly angled on the upper surface. The blank now sort of resembles a wing except that it is flat bottommed and partly flat topped, what's missing is camber and under camber. Softened in warm water the blank is bent along it's entire length over a piece of dowel or a pencil until the desired effect is achieved. Any necessary trailing edge cut out and reflex curve or wash-out should be tackled at this stage.

Preparing the wing skinning is as for a conventional balsa core wing. The skin is formed from 10 thou plastic card scored on the inner surface with a ball point pen. First lightly mark out in pencil the upper and lower surfaces of the wing onto the card, then carefully mark the rib stations before cutting out the piece oversize in cord. Place the card on a paper pad or magazine and go over the ribs and other raised detail with a ballpoint and straight edge, try to make just one pass for each rib station and lighten the pressure slightly for false ribs or half ribs. Lastly the leading edge should also be scored to permit folding.

Skinning the wing follows the same proceedure as described by Harry Woodman for re-skinning kit wings. First attach double sided adhesive tape to both surfaces of the wing core leaving a 1/8"-1/4" margin all round. Mark and remove a thin strip of tape at control surface hinge lines and center section or dihedral breaks. Remove the backing strip from the double sided tape on the lower surface only and attach the skin to the core. Run liquid cement around the edges of the lower surface skinning to fix it to the core. Mekpak is recommended for this job, but whatever your preferance use it sparingly or puckering will result. With the lower surface now secure trim of the excess from the trailing edge. The razor sharp trailing edge so carefully prepared is now 10 thou thick and must be restored by careful sanding. This done remove the backing paper from the double sided tape on the upper surface and repete the process. Using the conventional method I have always had difficulty with tip profiles, with an all plastic scratchbuilt wing I have no such problem.

Control surfaces cannot really be scored using this method. Remove them, seal the edges, refine and glue back in place. Dihedral breaks or seperate center sections should be approched in the same way, and drilling holes to accept struts or bomb racks etc is exactly as for an injection molded kit.

This technique is as useful to the converter as it is to the scratch builder, as illustrated by the Albatros DI depicted on this page.Though intended for 1/48 scale modelers it can be applied to larger subjects in 1/72 and the core can be used unskinned with rib detail scored directly on to it for smaller types. I believe it holds few terrors for a generation of modelers raised in the plastic age and not used to balsa or other strange organic substances and the materials are cheap enough to allow mistakes. After a couple of practice sessions any competent modeler will be an expert. Try it.

A New Twist on an Old Technique