Vickers Viking (oz2760)

About this Plan

Astral Vickers Viking. Free flight scale rubber twin motor model airliner.

Reprinted later in Aeromodeller, along with a two-part article by Doug McHard detailing his search for this most elusive Astral model from the 1940s.

Quote: "Last time, I recounted the jumbled events surrounding the return of the 50 year old Astral Viking kit from Australia. The design had 'disappeared' after its brief distribution in 1946 and for many years I had wondered just how this unique CH Saunders designed twin stacked up against the other well known Astral twins, all of which were designed by HJ Towner. Now that we have a 'mint' kit to examine, what impression does it leave?

To be frank, Towner's designs are generally much superior for accuracy, engineering, and drafting. But as a model lost for half a century, and one of some significance in the Astral story, it had to be built and, hopefully, flown.

I eagerly looked forward to re-creating this interesting model, but it was clearly going to be a time consuming project and I did want it to stand a good chance of flying and surviving the inevitable rough and tumble of trimming. My approach to a project like this is to retain the orig-inal designer's concept and make only the changes that experience suggests are essential for success. No extra ribs or stringers, no changes to sections or outlines, except for minor cosmetic amendments. However, I am not averse to altering such items as incidence angles; rubber anchorages; cowl attachments; adjustable tailplanes; plug-in landing gears and including some in-filling between nose stringers.

It is important that the finished model should look like the original, and present to the observer a close approximation of the designer's vision. It should also provide the builder with the experience of building the original kit. Saunders has closely followed Harold Towner's method of construction in that the model is built directly on the plan view; virtually everything above the datum line being completed before removing the assembly from the building board, inverting it and then adding the bottom half of the model.

This method can certainly help to avoid misalignment, but it is tedious and, in the case of the Viking, it produces not only an inaccurate fuselage profile but also results in a zero incidence wing setting, which comes much too high on the fuselage. Because this latter adversely affects the aerodynamic set-up, I built the wing centre section separately and mounted it later at a positive angle of incidence after fining the lower fuselage formers, but before adding the lower stringers. The wing trailing edge is actually lowered by about 3/8 in. The engine nacelles and cowlings are arranged to remain parallel to the fuselage datum, thus building in some necessary downthrust. The model needs, in relation to the wing zero lift line, about seven degrees downthrust.

The wing centre section is very highly stressed on all the Astral twins, the leading edge in particular needing substantial reinforcement for which I used a continuous piece of 1/4 x 1/8 balsa between the engine nacelles. I also redesigned the centre section mainspar to eliminate the serious strength-sapping rib notches..."

Update 05/11/2012: replaced this plan with a clearer version thanks to mikewight and his post on HPA.

Supplementary file notes

Article pages, text and pics.

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