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Design concepts from Lynn Williams

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cluttonfred

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Here's another missive from Lynn Williams prompted by some recent threads including quite a bit on a proposed scale Polikarpov I-16 called RAT16.

Hi again, Matthew.

Looking again at the Homebuilder's site, I note some references to the Lympne Trials types and recall a lightweight Vickers Viget I drafted a while ago, for a flat-twin with PSRU - about the same time I was considering an 80% Sperry M.1, both pre-dating the Z-1.

I also drafted an all-wooden Comper Swift, intended for a Half-VW or similar. This utilised a pair of modified Currie Wot wing panels (reflexed Clark YH, chord 42") with the ribs cut off behind the rear spar which was deepened to full profile depth. Extended rib tails were added without the reflex, resulting in a final chord of 48", accurate for the Swift, the final section being a very slightly-slimmed down Clark Y, also appropriate for a Swift. Wing folding was not considered, for simplicity, but the panels were to have been extended with scarfed and ply-clad spar extensions and elliptical tips, the forward spar having also been deepened to full profile depth and D-boxed for torsional rigidity.

Due to much of the TE comprising aileron, the surgery to the wing panels was not particularly onerous, since those rib tails would be removed in any event. The interplane strut positions were revised to accommodate the correct position for the Comper lift struts.

A much simplified, one-piece all-wooden fuselage was drafted and the idea was to use the narrow chord wheels and elegant, lower profile shape for the fin and rudder of the early models. Even a stock, un-geared VW would have looked OK with the long bullet cowl of the first Swifts but then, amazingly, an original 60 hp. Pobjoy P, forerunner of the R, was offered for sale: the P was used following the Salmson AD.9 in a progressive increase in installed hp. as the type evolved.

Sadly I was in over my head in design matters and I let the Pobjoy slip away. One 'Comper' wing remains in store with the other unmodified Wot wing and I loaned all my Comper patterns and research material to someone making various parts. I now have all available genuine Swift drawings but I find that once fully-detailed data is available, it is more difficult to rationalise building a 'lesser' example, especially when such lovely accurate reproductions keep appearing, such as the beauty built by the late John Greenland.

I see that Autodidakt enthuses over the Fokker V.40. The similar V.39 with a small rotary (flat-four in a cosmetic cowl) was a type which I also sketched with a view to building back in the mists of time. Victor Bravo's reminiscences of Ernst Kessler et al from George Roy Hill's epic, The Great Waldo Pepper, leads me to reflect that his name may have originated with Ernest K. Gann's 'Company of Eagles', and has become my own Nomme de Guerre, typical of the Teuton names bestowed on Flitzer builders of the Flitzer Sportflugverein, such as von Schneer, von Schmirk und Spatzendreck. Kessler reappears as a central character in my novel, The Baltic Falcon, although it's in the planned sequels that the Z-1 Flitzer Luftschiffparasitapparat makes its full debut.

I attach an image of Kessler's Goblin which also makes a brief appearance in TBF.

Finally, following on from the Yak UT-1, a slightly later Russian design project was the Polikarpov I-16, work name RAT16.

This would be constructed very like the original, with spiral wound ply-strips in two opposing layers, glued to a sub-structure of substantial longerons and light stringers, to form a monocoque shell with an aluminium tailcone. The forward fuselage would be a steel-tube space frame with aluminium sheet covering over curved ply stiffening. This would house the retraction system: a steel spider-supported wheel on the front face of a suppressed firewall bulkhead, winding-on two stranded cables using a cockpit hand crank.

Two lignum vitae or similar bobbins supported from the asymmetric yoke would convert the cable runs to a vertical pull for the last part of the retraction cycle, the wheels retracting ahead of a deep box spar, rather than between the more widely separated warren spars of the original.

The engine truss would bolt onto this space frame and various engines could be installed, fully concealed within the louvred radial cowling. Further details appear in the emails below.

As ever, feel free to share.

Beste Fliegersgruesse,

Kessler

PS. The pretty Z-1S Spezial, G-ECVZ, is being rebuilt following its landing accident last October. It may now feature streamlined wires and an up-rated 107 hp. UL Power motor.
 

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