SOJUS
Scratchbuilt spacecraft in 1/48 scale
History
After six flights with the single seat Wostok and two flights with the multiple seat Woschod spacecraft a novel spacecraft was planned for the proposed trip to the moon. It was named „Sojus“ (union, alliance) and was composed out of three major modules: a cylindrical equipment component with devices for energy generation and the powerplant, the bell-shaped command capsule with space for up to three crewmen and a sphere-like orbital section. The latter one was used as a lab for scientific research in autonomous flights and was therefore equipped with various additional hardware including external devices depending on purpose of the respective mission. If coupling to another spacecraft was planned, a docking aggregate was attached to the front of the orbital section.
Manned flight tests began in 1967. Sojus 1 with Wladimir Komarow took off on April 23. It was planned that Sojus 2 with three crewmen should follow the next day and serve as a coupling target for Sojus 1. After cancellation of the Sojus 2 flight due to technical problems with Sojus 1 Komarow was deadly injured after landing when the parachutes failed to open. Not until October 1968 the next cosmonaut travelled into space in Sojus 3. The planned coupling with the umanned Sojus 2 craft was cancelled due to technical problems. With the flights of Sojus 4 and 5 in January 1969 the first successful coupling and exchange of two cosmonauts (at that time still externally) was achieved. The type designation for the spacecrafts used in these missions was 7K-OK. Later crafts received different codes and since 1971 were primarily used as shuttles to the Saljut stations. All together 40 Sojus spacecrafts as well as 15 optimized Sojus-T and 30 Sojus-TM variants were launched. Currently the further modified Sojus TMA is used for service flights to the ISS.
Scratchbuilding of the master model
Although being the most frequently built spacecraft on earth only one useful kit was available for a long time. It is made by the Russian manufacturer Ogonjok in 1/30 scale, fits well and is detailed. Nowadays it is hard to find and only available from collectors or in auctions for up to € 250,- (appr. $ 300,-). Sojus parts in 1/96 scale derived from Revell’s ASTP kit (ASTP = Apollo-Sojus-Test-Project) as well as Sojus TM models in several space station kits are useless due to the scale. Meanwhile Realspace Models sells a Sojus TM and an ASTP kit in 1/72 and Marco’s Miniatures a vacu-formed ASTP kit in 1/48 scale.
When I finally wanted to start building a Sojus model in the beginning of 2000, the Ogonjek kit was too prized, the Realspace kit too small and the Marco kit too hard to get and only poorly detailed. Therefore I started scratchbuilding an early version Sojus spacecraft in 1/48 scale. The idea to use the parts as master parts for a novel kit came from Tomas Kladiva, the owner of „New Ware“ kits, when the major components were roughly finished. New Ware from the Czech Republic is well known to space fans among the modelers. Tomas knows how to upgrade poor space model kits of big manufacturers with the help of excellent PE sets and decals.
I started the scratchbuild project with an empty deodorant can. After adding a 0.5mm plastic sheet to the can it had a diameter of 46 mm needed for the instrument section. For the easier application of the sheet using UHU-endfest glue, the rectangular polystyrol sheet was attached to the can by tape and warmed up in an oven until permanently cylindrically formed. It is advisable to drill a small hole into the (empty!) can to allow expansion of the inner air. The conic shaped stern apron of the instrument section was build out of a funnel with correct angle.
In contrast to the regularly formed instrument section both the bell-shaped command capsule and the stretched sphere-like orbital section caused problems to the scratchbuilder especially as I do not own a turning lathe. I decided to use the slice construction method. With the help of a mini drill numerous 1 mm plastic disks of different size were produced. For further treatment these were attached to a mandrel normally used for cut-off wheels. I previously had determined the exact diameters from a blueprint of the orbital section and command capsule in the same scale. Afterwards the plastic disks were mounted on a piece of steel wire, exactly positioned with the help of spacers and finally glued together. At sites of strong curvature I omitted the spacers and directly connected the disks with glue. The gaps and irregularities on the surface were filled with Revell Plasto and smoothened by filing and sanding. The obtained surfaces are not comparable to those obtained with a turning lathe, but fortunately this is not necessary. The Sojus spacecrafts are usually covered by several layers of insulation blankets. These protect from temperature variations and micrometeorites. Therefore the structure of these insulation blankets had to be added to the sanded surfaces of the orbital section and the command capsule.
To obtain a realistic drape by milling a lot of flair is necessary. Alternatively many modellers use wrinkled aluminium foil with proper priming and coloring after glueing. The little folds look realistic at smaller models, but not at models of larger scale. After several trials I ended up with the following method: for the insulation I applied 1-2 mm of a two-component glue (e.g. UHU-endfest) on the appropriate part, then this is wrapped into thin clingwrap (e.g. home garbage bags) with 5-10 cm of excessive foil on both ends. For lengthwise folds the excessive foil is rolled like a candy wrap and fixed. 12 hours later the glue is set and the foil can be removed. Fortunately the plastic foil cannot be glued by two-component glues. Depending on the accuracy during wrapping small air bubbles might have been formed, which now can be removed by glue or putty. Afterwards again glue could be applied at some spots and covered again with foil. Depending on the twisting or stretching of the previous foil multiple characteristic effects can be produced. The joints with the little wrinkles (Sojus orbital section) were introduced by spanning thread over the foil at some sites. This method requires patience and initially leads to sticky hands and loud maledictions, but to my opinion the result is worth the efforts. The front of the coupling socket is not covered by green blankets, but rather with some kind of metal foil. First a plate-like turned plastic disk was soaked with plastic cement, then carefully wrinkled aluminium foil pressed on the disk and finally removed after one day of drying.
The ring shaped container at the back faced a difficulty. In the only available picture of a flightworthy Sojus spacecraft showing this container it was uncovered, which meant a continous surface. After an unsuccessful search for a suitable shower curtain ring I decided to try two component plasticine. This is produced by several manufacturers, the most famous being Miliput. Due to the better availability I used "Epoxi-Kitt" produced by Greven. After dispersing both the dark grey and the white components (appr. 5 min) rolling between two plates of Plexiglas formed a cable of appr. 10 cm length with a diameter of 11mm. Two Plastruct tubes with a diameter of 11 mm served as spacers. The cable then was bent around a cylindical part, which exactly matched to the inner diameter of my container. After curing this led to a ring segment of appr. 200°. After repeating the procedure for a second part both were cut to a 180° segment and glued together at their front ends using UHU endfest. To remove small cuts and other irregularities the ring was primed with Revell "Basic Color". After polishing the ring was used to create a silicon mold in order to continue working with resin copies.
The edge in the middle of the ring again was produced with my mini drill. Masking tape was wrapped around the drill chuck in order to allow slipping on the ring The edge was formed with a nail file by slowly turning the ring. Small plastic profiles (0.25 mm) were attached to represent the wiring. Further details (like cover plates or attachment points for sensors) were drilled from a 3 mm rod and inserted into holes previously drilled into the ring.
Also the wiring and pipelines on the radiator of the hardware section were made from 0.25 mm rods. To reproduce equal and parallel distances between the individual wires a mask made of precut masking tape was first attached to the coat of the section. This masks covered everything except those parts that were supposed to carry wires later. For the attachment Contacta Liquid was used very sparsly on fragments of the profiles (appr. 5 cm in length) and carefully pressed to the desired location. The next profile segment was then covered with glue and attached in a way that the blunt ends are connected. After drying all connections could be corrected with careful sanding to remove any existing gaps.
Some antennas and the solar panels were produced as photoetched parts. Meanwhile there are several companies in Germany that produce photoetched parts from electronic files (e.g. CAD or CDR-files) for money. The production of these parts works as follows: First a metal sheet is needed that has been covered with a light sensitive varnish on both sides. Then two masks with the layout of the etched parts are necessary. These masks made of film will be applied to the metal sheet (usually brass) and irradiated with UV-light. After rinsing the metal sheet in developer some regions are protected by the varnish, others are unprotected and will be exposed to the etching procedure. Since most of the modelers probably do not want to buy a complete etching equipment, they are left with the design of the layout and subsequent visit of a company offering etching service. Some hints for the design of the layout: the software used should either be a graphic program capable of dealing with vector graphics or a CAD program. It is advisable to ask the service company beforehand for suitable file formats. There are two layouts necessary for a PE-plate, front and back. On plates covered with a negative laquer all black areas from the layout will be exposed to the etching process, all white areas are protected. Areas that have to be completely removed need to be represented as black areas on both layouts. Areas with only one black layout mask will only partly be removed by the etching process and leave a structural surface like the back of solar panels. It is important to note that one layout has to be inverted, but otherwise both are completely congruent. For best results first use a single graphic file. All areas that have to be completely removed should be represented in black. For areas that should only partly be etched it is recommended to use two different other colors, e.g. red for structures on the front and green for those on the back. Additionally to the layout the file should include fine crosshairs in each of the four corners drawn with the finest available lines. This will later enable an exact alignment of both layouts.
After finishing the layout the whole graphic should be copied into a new file or on a new page and one of the graphics should be inverted. Then all green parts should be removed from the layout for the front and the red areas be replaced by black ones. The same should be performed with the layout for the back, but vice versa. For the decision, which of the two graphics should be inverted, it is important to know, how the layout will be transferred to the film. The reason is that the black areas of the film are only attached to one side of it (coating side) and do not reach all the way through to the other side. It is exactly this side that should face to the plate during irradiation to avoid irregular edges. Confusing consequence: In most cases the layout for the front needs to be inverted. Best is to ask the technician in the etching service and how he prefers the layouts.
The minimal size of details that can be used in the layout depends on the thickness of the available plates. As a rule of thumb details should not be smaller than the thickness of the plate. At areas, which need to be completely etched away add 0.1 mm to the rule. Etched lines that should facilitate easier bending of parts should match the material thickness. The little bars holding the parts within the frame should be a little wider than the material thickness. In case of the PE set for the Sojus, which was produced from 0.16 mm plates the bars have a width of 0.3 mm. The areas that need to be completely edged away should be kept small in order to provide more stability to the PE set.
Final remarks
When I started with the project I didn’t expect it to become a kit. Thanks to the convidence of Tomas Kladiva I started with the master mold after having finished half of my model and I have learned a lot on resin casting and photo etching. End of March 2001 I had to part with the master copies. Two weeks later I received the first casts as a replacement. Again six weeks later the instruction manual and the image for the box were finished, all decals printed and the PE parts etched and since then the kit is available from „New Ware“. I still haven’t realized my original intention to build a 1/48 scale Sojus spacecraft- the pictures were taken from a model built by Tomas.
Andi Wüstner
German Space Exhibition Morgenroethe-Rautenkranz e. V., section modelling
References:
New Ware: http://www.mus.cz/-ales/new-ware/
Sven Knudson’s space modelling site: http://www.ninfinger.org/~sven/models/.html
Space in Miniature: http://www.inficad.com/~mjmackowski/index.html
Mark Wade’s Encyclopedia of Spaceflight: http://www.astronautix.com/
German Space Exhibition: http://www.morgenroethe-rautenkranz.de/ausst.html