Sikorsky S-40, hand drawn

[papermodelfan]

I preface this by saying I am a long time builder of paper models, but not a designer, at all. I have no graphic arts software, and no experience with Sketchup. However, my wife may be the last architect in Atlanta to still do all her design work at a big drafting table with parallel rule and pencil and ink; so as long as I can stay out of her work, I can explore the trigonometry of design graphically and work in large scale formats on paper.

I got hooked on this after building the FG Sikorsky's S-39 (designed by forum member Mauri Liso) and S-38 (by Glen Volyn), both of which I enjoyed more than almost any other models I have ever built. Part of the charm is the clever sculptural solutions in the designs, and part is the wonderful retro sturdiness of the Sikorsky's themselves. I wanted the sequel, and decided to try it at home. I am aware of Bob Bendorff's nice model of the S-40, but wanted to try myself to capture the curves in something more like the FG design style. So I collected photos, and 3D views off the internet, corresponded with the Sikorsky archives, watched the Fred Astair/Ginger Rogers movie "Flying Down to Rio", and and with Don Boose's help, read two contemporary aviation magazine articles.

The plane itself was conceived as the 4 engined version of the S-38. In fact, the initial design sketch looks like a stretched S-38. At the urging of Pan Am, the only customer to step forward as the economy collapsed, it was greatly enlarged. At the time it first flew, it was the largest airliner in the world, with 44 seats. Pan Am bought three, and flew them out of their seaplane terminal in Miami, across the Caribbean and down to Rio. Pretty luxurious way to go, with dark wood paneling inside, comfortable seats, and a rear smoking lounge. They always operated off water, so did not need airport landing strips, but had retractable wheels, in case of a forced landing on somewhere like Cuba. Over time , the wheels were abandoned, to save weight. Eventually the engine cowlings were also abandoned.

The aircraft is full of Sikorsky special touches. The robust hull really is a boat - with cleats, mooring lights in front, portholes in back ( a constant Sikorsky touch from the Russian Le Geant to recent helicopters), a generous and comfortable breadth, and hatches on top for entry. The design depends on two lower spars to carry the loads from floats and engines - like a phantom lower wing. A ring on top of the hull could carry a spare motor, if needed. Not at all streamlined or fast, with a cruising speed of 115 mph.

I also have been very slow. I started on this back two years ago, and have proceeded in fits and starts, as spare time has been rare. So I began by enlarging the 3 view to the 1:66 or so of the Regular size FG Sikorsky's, test building versions of the hull, and adjusting the design. I didn't attempt anything with the engines. The end result of this phase is shown below. The hull is a single top, a piece on each side, a fore deck and three pieces forming the underwater portion (there are two steps). No interior formers at all, except for a half bulkhead at the forward step, and the two lower spars go straight through the hull.

Now I have enlarged the design to 1:33, refined many points, and started trying different versions of representing engines. I will be test building this scale now, and completing the pencil version. Will provide design updates from time to time, describe some of the headscratching. This newbie appreciates any and all comments.

[OhioMike]

Outstanding work Rob!!! I do the same thing, went to drafting school an all....before computers!!! Presently trying to design the Curtiss H series of biplane fying boats! A Pre war submarine, and a 70' & 77' PT boat, and a Civil war ship, and........
Mike

[mchale]

Oh I want one I also want one of Ohiomikes pt boats and flying boats

[Don Boose]

Wonderful narrative, Rob!

I enjoyed seeing the profile mock up of the 1/33 S-40 at the IPMC last October and am glad to have played a small role in providing the AAHS Journal and Skyways articles.

Hey feller, twirl that old propeller,
Got to get to Rio and we've got to make time.

I'm glad to see this project officially underway and look forward to seeing one of my all-time favorite Golden Age airplanes take shape.

Send a radio to Rio de Janeiro,
With a big hello
just so they'll know and
stand by there,
We'll fly there . . .
We're singing and winging our way to you.

Don
(With credits to Nincent Youmans, Gus Kahn, Edward Eliscu Edward, and the sempiternal Fred Astaire.)

[murphyaa]

That looks pretty good Rob. I'm still working my way up to big seaplanes.

[birder]

Cool stuff!! you know once the boat part is done the rest follows much more easily, and if the nacelles are the same, then some ease in design. Keep it up! Cleaning up the lines and standardizing the parts symmetrically R + L, makes it easier yet, with Elements is not really as hard as you might think Cool project for sure

[rmks2000]

Rob

Great to see you trying your hand at designing. It looks really good so far. I've always wondered how smooth the landing was for passengers on flying boats. back then I imagine you had to be pretty adventurous to travel by plane.

[cdavenport]

What were the engines; Wright Whirlwinds? Nevertheless, in 1/33 scale you could cheat with plastic engines. Good luck on the design/build! Looks pretty cool so far.

If you are interested, I have a great technique for forming cabane struts which also ensures perfect attachment and alignment to the model.

[wag]

The engines were P&W hornets. I found a little inspiration for you.
Sikorsky S-40 Flying Boat - YouTube
Wayne

[papermodelfan]

Thanks to all for the encouragement, and thanks to Wayne for the lovely video clip, with a sound track, no less. The engines have been the biggest challenge to me, and I have been experimenting with them; There is a lot to the Hornet, including the complex rocker head shapes at the top of each cylinder, and then there is the big perforated dish in front to manage the cooling air flow. Think I have finally reached an all-paper solution that remains pretty easy to build, with or without the cowling.

C Davenport. My solution for the maze of struts has been to draw them out geometrically, and build them with a little basswood strip within. Alignment and strength mean everything in this design - I am curious to know how you approach it.