The glider:
Before being recognized as the father of the soviet space program, Sergei Korolev was already a proficient designer and engineer, whose gliders had achieved considerable success within the Soviet Union. In the time between his early success with the SK-4 and the SK-3 Krasnaya Zvezda high performance aerobatic glider of 1930, which would evolve into the 1938's RP-318 rocket-propelled laboratory, he designed along Sergei Lyushin the SK-5 "Koktebel". It was a high performance glider of impressive layout, with a straight, shoulder-mounted, 17meter long wing of considerable span and tapper using a novel aerodynamic TsAGI profile, its 7,75 meters fuselage being oval in shape and the rudders of the all-moving type. It was a robust machine built of wood and fabric which was refined over the years with an improved, more streamlined nose and cockpit deck cover. It woould land on two wooden skids, the main one being notable for its canvas cover giving it a "cod belly"-likeness when in flight. The "Koktebel" name was a proper homage to the crimean city where the main glider contests took place at the time. Despite being quite heavy for a glider of the time with its full flying weight of 300 kilograms, it had a very respectable performance, with excellent flying characteristics and aerodynamic penetration, its lift to drag ratio being of 25:1 which was the same of the contemporary Akaflieg München Mü3 Kakadu - also of 1929 vintage -, but without the structural flexion and torsion problems which would plague its german counterpart throughout its long and distinguished career.
The early style of cockpit coaming is clearly visible here, with Korolev standing beside the machine. The amount of leather padding is noteworthy, as is the tape covering the wing and spine union.
The early colour scheme is said to have been red and yellow, but the reflexion of the lighter fabric parts could also tell-tale an aluminium based coat.
When the "Koktebel" first appeared, the nose hade a greater tapper and blunt design than the rest of the fuselage. The rear part of the skid cover is visible under the wing root, with its fabric overhang when resting on the ground. The dropped down design of the wingtip's upper surfaces was interesting and aimed to protecting the ailerons while providing a generous surface for the airflow, so no twist of the trailing edge was required as in other machines.
Here the clean design of the long fuselage is visible, as the broad ailerons and slender all-moving control surfaces.
A rare view of the "Koktebel" in flight. The cleanness of the design is quite remarcable.
The great empty weight dictated the use of a towed cart when carrying it to the launching point.
"Koktebel" Vol.II we might say, the lengthened nose gave it a better aerodynamic and lesser air got trapped by the higher cockpit coaming even if it impaired downward visibility a bit. The double, fabric wrapped air tubes attached to the Badin aerodynamic tube and the fairing for an instrument in front of the pilot made this late version of the glider the one to build.
The two Sergeis, Lyushin and Korolev, and Artseulov posing with the SK-5 during a photoshoot. The colour scheme is a mistery, but given the lack of reflection of the lower fuselage, it could be light grey or more likely aluminium, the uppers could be Protective Blue-Grey or Turquoise, the red and yellow (aluminium perhaps) scheme being ruled out for they don't photograph like that in most films of the era.
I found this very nice colorization of the previous photograph and had to share it with you. If you happen to know the artist who rendered it, please let me know so I can recognize his work.
This plan was scaled to 1/72 and suitably modified to build the later "Koktebel".
The model:
As usual it begins by the fuselage - the cockpit in this case - given the "cod belly" for the skid.
It needs to be a strong but simple structure, so 1,5mm plastic sheet was used. UHU's glue for plastic gives an result bonding the different parts.
There are no pictures of the interior, so it was created basing it on contemporary gliders.
The rest of the fuselage was then cut, shaped and glued fore and aft the cockpit section.
Next, interior painting. It was done with Tamiya XF-15 Flat Flesh as a base, the given the Faber Castell watercolour treatment.
With thatdrying up, the wing's center section was cut and filed to shape out from PVC Foam sheeting. This materia is great since it can be flexed in a given axe, but is very rigid transversally. The all-moving control surfaces were cut from plastic card and sanded to shape.
The fuselage was covered in sections with curved plastic card.
The cockpit covering was done in the same fasion, the innards painted with a light, pinkish, cherry wood - like hue.
Then the grain was applied with Faber Castell regular pencils. They tend to "grab" and work better on glossy surfaces than the watercolour ones.
The outer wing panels were fashioned from the same PVC Foam stock. It's very workable, but a respirator is recommended when sanding by hand or rotary tool. If wet sanded, even better.
Next, the spine. PVC Foam cut roughly to the shape. It will be sanded later.
The wings, almost finished. One word of caution regarding PVC Foam. It's easily dented. So care must be taken not to leave any marks on the surface. That led to some extra puttying and sanding later.
The nose and tail cones were fashioned from a sandwich layering of plastic card, for they will provide protection and strength to the overall structure.
Wings attached and it's starting to look like a glider!
UHU's glue for plastic was used. It sticks the PVC Foam parts almost instantly, melts the joining surface and is easily wet sanded.
The cockpit coaming was attached and it gave some issues due to its multiple angles. Curved at the front, it touches inside the wings and has two flaps whi surround the headrest sides.
Another overall view. The tail surfaces give it a shark-like appearance.
Final step before priming: the wing junction covering straps.
Checking the overall sit of the pieces. Nice.
Primed with an old Molak enamel colour. Try not to spray-can the PVC Foam, for the solvent will most likely attack the surface and melt it.
The skid was prematurely given the wood-grain effect treatment and attached to a piece of old air mail letter paper. The nice thing about this kind of paper is, it's light, folds quite well and adheres strongly when soaked in a water / white glue mixture.
Thins strips of air mail paper where attached to the edges of the covering to portray the covered stitching of the original.
Lots of touch ups and sanding there!
It replicates fairly well the wavy appearance of the original canvas covering.
Onto the main event. Humbrol H-48 Mediterranean Blue fits great the grey scale of the two photos found of the "Koktebel" in its second iteration. Hataka's excellent AII Aluminium was used for the remainder of the structure.
Now we get to the drama part. The black decal strips strated to "bleed" once applied. Don't know what happened there, but even the touch-ups with thinned black acrilyc paint attacked the decals. it was a case of stripping down the fuselage and repainting or letting it be and find another way to do the fuselage striping. "Never reinforce defeat" once said someone. So i stopped fiddling with it.
The twin Pitot and single Badin feed tubes were made of syringe needles of various dimeters, the twin tubes wrapped around with some air mail paper strip.
The cockpit leather coaming and headrest where base-coated with Model master's Italian red Brown and then highlighted on the edges with Humbrol's H-186 Leather Brown.
The main skid and canvas covering were given a dusty appearance with acrilycs and a subtle drybrusing. the panel lines were given a light wash with a neutral dark grey mix since they are noticeable on the photos.
Onto the final result:
And that's it. Another finished model of a forgotten but significant machine by an important designer, never expected to be seen in kit form, with the added joy of being scratchbuilt.
As I'm writing this, my thoughts go to my father. It was his buying a tiny 1/100th scale Heller helicopter that started me down the scale modeling road. He's passed away this last tuesday, November 24th. For all it's worth, thanks Dad.
Until our next installment, take care and good luck.
TMU.
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