Solid Model Masterclass-Building undercambered wings

[Balsabasher]

If there is one challenge faced by modellers of early aeroplanes its the fact that they often employ wing sections that have under camber,to carve this successfully into wood is virtually impossible and having attempted to do so on my Slingsby T-21B glider solid model never again ! there is a much easier solution to this problem and it entails making a simple jig that can  used again and again to make great wings with undercambered aerofoil sections such as were used on many early WW1 aeroplanes and also private aircraft of the 1930's period.

Here is part one of this tutorial which covers the construction of the wing jig,as a deciding factor I selected a typical early wing section that can be modified by sliding the wing about the jig fore and aft to increase or decrease the amount of camber,you can select any section that you feel you use most and to any scale that you want,the time and effort is well rewarded in the very effective wings that can be built  utilising these jigs that have been developed over many years of model building.

Firstly get hold of a flat building board and mark it out with the respective aerofoil stations required,these aerofoils are your basis for the undercamber so take your time in cutting out the ribs which can be cut from quarter of an inch timber,lay them out so that you can later use the upper portions of these ribs to help in the construction of the board,all will become clear later.

Next glue the ribs to the board at a reasonable distance so that the true aerofoil shape is peserved,when these are fully dry select a piece of ply or balsa sheet that will effectively wrap around the ribs forming the base for your model's wings,use some contact adhesive to glue the formed sheet into place,now you can utilise the upper portions of the ribs you cut out carefully to pin down onto the top of the sheet at strategic points while the adhesive dries,every little helps at this stage with the accuracy,the pictures should give you a good idea of how it looks at this stage of the construction with the trailing edge of the sheet held firmly to the board.

The next tutorial will explain howto build your undercambered wings directly onto the jig and which materials to use for the best success.

Barry.













Here are some wings built with this method on a RE8 'Harry Tate' biplane.



A bunch of ready formed wings all ready for shaping to plan form,the section always holds it shape because the aerofoil is locked into position by the building process to be described in the next tutorial.

[Balsabasher]

Now the jig is ready for use,to make a wing panel tape your preferred thin sheet across the jig with masking tape,spray water onto the upper surface to relax the sheet,allow to dry out overnight before adding the next sheet,repeat the operation and you will have two nicely formed panels that just need glueing together utilising the jig again,once cured you can cut the panels to the required size of the wings.
Barry.