Sikorsky S-39 "Spirit of Africa"

[g_kandylakis]

The title must ring a bell... To long time members of the initial HPA that is.

Started back in 2018 as a long term project and put on hold a number of times, being overtaken by other projects...

Restarted again shortly in 2025, then paused again in order to build my Moth Major peanut and to finish my Batboat. With these out of the way now, it might be getting back into construction.

Another equally complex project is also on my list, but before I start it I thought it would reduce some of the guilt, if I finished this one first.

An indoor model at 1/24 scale, for free flight and RC, with a rather complex but most interesting landing gear which I wanted to be a working retractable one.

The initial thread on HPA is gone of course, as is the restart of 2025. I thought there was no evidence of it online until I checked our greek forum. And yes, I did post about it in 2019, with a link to HPA for more details. Still managed to post plenty of pictures documenting the progress back then.

https://www.aeromodelling.gr/ForumS/index.php?topic=53239.0

For those who might not understand greek, there is always google translate... 

[g_kandylakis]

So, what happened after 2019?

I do have the photographs I posted last year, posting them again will help me too, in order to remember where I was and where I was going to...

My initial plan to use polystyrene sheet for the hull covering proved to be a major braking factor. Once I had compromised for balsa things moved a lot quicker.

The hull and cabin tops substructures had to be prepared for the skin to be glued onto.

Also, the windshield vacuum forming plug started getting shaped.

[g_kandylakis]

The cabin interior will be visible through the side windows, so it would have to look good. Basswood stringers and balsa formers were added.

[g_kandylakis]

Hull top cover planked with balsa.

Contrary to my previous smaller S-39, I intend to place the battery in the wing center section and not in the hull, so I will not need to open it up too often. The top is held in place with magnets...

[g_kandylakis]

The cabin top has a double curvature along the edges so it was an interesting experiment to see how the balsa would conform to the needed shape.

Instead of making an extra form, I thought of using the existing structure, covering it first with wrap film to keep the water away. Many rubber windings afterwards and a sudden snap noise  and I realised I would have to make a form...

[g_kandylakis]

structure repaired, Windshiled plug also done more or less.

Cabin inside structure painted.

[g_kandylakis]

Now with a proper form, the top was formed in two halves. Not a perfect result but good enough, especially as you can sand and fill any irregularities on the light balsa wood.

[g_kandylakis]

the first half painted inside and glued in place. I went for a lighter gray color to avoid everything turning too dark. No light inside, or maybe?

[Crabby]

My dad, "Thee Olde Man" did a splendid watercolor of this plane as first prize in his annual ROW contest in the Florida Keys some years back. It was titled OSA's ark I think. Nice job George. I like your approach to modeling. Well done mate.

[Robert McKellar]

Beautiful work and very inspiring!

[gravitywell]

Doesn't Kermit Weeks at Fantasy of Flight have one of those in flying condition?  Seems to me its done up in the African Giraffe paint scheme.  Very cool build.

[g_kandylakis]

My dad, "Thee Olde Man" did a splendid watercolor of this plane as first prize in his annual ROW contest in the Florida Keys some years back. It was titled OSA's ark I think. Nice job George. I like your approach to modeling. Well done mate.

Hi Crabby, if I am not mistaken, you posted a picture of the painting in my original thread in the original HPA, correct?

Robert, thanks...

Glenn, yes, he has a restored Sikorsky named "Spirit of Igor" in honor of Igor Sikorsky, finished in the colors of "Spirit of Africa", so basically same color scheme. But it has a cowled engine instead of the exposed one of the "Africa".

[Crabby]

Yeah my bad. I'm kinda mixed up with all the forum changes and what I posted when and where. I go back to SFA. I'm sure I'm redundant.

[Anyun]

Nice to see this wonderful build moving forward again! I remember it from old hpa. /Andrea

[g_kandylakis]

Nice to see this wonderful build moving forward again! I remember it from old hpa. /Andrea

Thanks Andrea, yes it was quite a long thread back then...

You forgot to add the word "slowly" before "moving forward" though  .
My very optimistic plan is for November IIFI. A more realistic one is the BMFA Indoor Scae Nationals in 2027. Which probably means, it might be ready for November 2027 IIFI...

Anyway, things are moving along, now focused on the wing floats. All balsa structure, being planked by 0,5mm sheet. The Tamiya yellow tape has proven to be an invaluable aid when building, for holding things together while drying.

3 segments per surface, because of balsa sheet width limitation. Actually the bottom is mor like 5 segments because of changing geometry of the V form.