1/72 Scratchbuilt Tunison Scout

Note: the completed model posting is here:
http://wingsofintent.blogspot.com/2014/03/tunison-scout-completed.html
This is the building article:

The Tunison Scout, flown for the first time in 1928 (by no other than Jimmie Angel!), is a remarkable plane in many respects. Not only it favored the then rare cantilever low-wig monoplane formula, but also used and partially pioneered construction techniques (a plywood-molded wing with no spars, also plywood molded fuselage and trousers, among other things), plus offering a fully-enclosed -but removable- cabin. The way in which today's high-performance aircraft are made, selectively layering carbon fiber, kevlar and such, is exactly the same.

In most photos an X-247E registration can be seen, but at least two images show its other X425 registration on the wing. Further down the lane it was re-engined with an inline Miller (which changed the nose shape and also introduced an alteration of the aft fuselage) and re-registered as X13795.

The plane was successful and flew at notable speed, and also landed safely and reportedly was pleasurable to fly and control. As many other pioneering endeavors, it did not get the sales it deserved, but got quite a buzz on the specialized press, and I gathered articles from many sources, locally and abroad, among them Les Ailes #398 of 1929, L'Aerophile Feb 1929, Aviation July 13 1929 (This source, by far, is the richest in information and details, and was the main reference used to correct and modify the existing plans, all quite inaccurate in many regards), Popular Science Monthly April 1929, Popular Aviation, Sept 1930, Wings Magazine of August 1978, and snippets and bits on many other magazines.

WW1 Aero magazine of Dec 1987 run an article on it too, with a plan that although not really accurate, is closer to the mark than all the others and a pretty good job considering that the author did not have access to sources other than a few photographs.

Research on this particular subject was spread through many years, and it took a notable amount of hours, better not count to keep one's sanity. This is almost invariably the case for most of the obscure/arcane/esoteric scratchbuilding projects, and it takes time, effort, dedication and unwavering intent. To give just an example of the subtlety of some features: the aft canopy -and therefore the overextended fin root- were purposely slightly offset to the left-seen from up and behind- to counteract engine torque, a written fact you corroborate looking very, very carefully to photos.

I have been scratchbuilding a number of mostly unknown types in the last years, far more than a hundred subjects by now, and I am very pleased that these strange jewels of aviation are brought back to life in 3D form. Aviation is a vast universe, full of mysteries and surprises, way beyond -and far more pleasant than- the arch-known and worn-off four or five war planes seen everywhere to exhaustion and repeated ad nauseam at model contests and exhibitions.

The Tunison Scout is not -configuration-wise- far removed from one of my recent projects, the Farman Tourisme 200, and they share the same design concept that brings forth those sort of clunky yet strangely appealing quasi-retro-futuristic lines. They even share the same Hispano-Suiza engine.

An Aeroclub aftermarket Hisso engine was used on the model (thanks, Armando!); the rest, regarding materials and techniques, is the usual gig utilized in other endeavors. Decals are of course home-made.

First the simpler parts are cut from styrene sheet. Accessories are selected:

The wings and pants wraps are prepared, Gottingen 387 and Clark Y airfoils are added to the root and tip:

 Fuselage frame assembled:

 Nose cone backplate added:

A spinner is carved and a part vacuformed from that plug:

 The master for the canopy is cut from wood:

 A vacuformed part is created:

 Tested:

 And a second is made to be sure:

Making the bucket seats:

Sheeting of the bottom fuselage:

 Some structure for the pants and the MV lenses used to replicate the landing lights:

 Preparation of the top fuselage sheeting:

 Some cockpit interior parts are prepared at this point too:

Metal control horns are made and glued:

 More detail parts are either adapted or fabricated:

The tailskid arrangement is made:

The general view so far:

The wing tips are filled with Milliput and sanded to shape. The ailerons are engraved, lead exits and horns are added:

The engine is given its exhaust stubs, made of jewelry crimping tubes:

 Some painting of components:

 The interior bits in place:

General view at this stage. Many details still needed, like Pitot tube, step, the engine strange exhausts, designing and printing the decals, etc.:

The bayonet exhausts are made from styrene rod and contrail airfoiled stock:

The pants are matched and glued to the wings:

The fuselage now has all its skin in place, control cable holes are drilled at this time.
The cut-out for the Hisso engine still needs to be done.

Another general view:

Decals printed:

The engine dry-fitted:

Some little cut-outs ahead of the leading edge position seen in photos are made. Through those the water radiator (located underneath the fuselage) hoses will run, as well as rods that seem structural or perhaps part of the mechanism the Tunison Scout had to vary the engine bearers line of thrust:

Assembly of the components begins:

Red is airbrushed:

 Then the blue:

Assembly goes on. The canopy and engine are glued, the elevator too, some decals applied. The canopy shows the entrance hatch and the front upper window.
A long list of "still to add": wheels, more decals, rudder, control cables, Pitot, lights, canopy frames, prop, spinner, step, exhaust bayonets, the two radiators, radiator hose, etc.

Some items have already been added, more to go:

A clear piece of spectacular styrene rod is heated and stretched, then painted to later represent navigation lights:

 Underneath: