Paper models, photos and musings of a Paper Kosmonaut

10 September 2017

Zil 4906 - The Soyuz capsule [1]

Hello friends. Now the Zil is finished is needs something to carry. So I started building a Soyuz capsule.

There is no 1/25 Soyuz spacecraft, let alone just the capsule. So I had to design one. And I am not really a designer. Also, I don’t have any 3D or CAD program to help me. This means I make things up as I go, using some online calculators, lots of photos and two good old Eyeball 1.0's (with a couple of add-on lenses in front of them to correct the blurriness close by...).

trial and error.
The capsule’s shape was the least of my troubles. I already have built it. Thrice. And it ended up looking quite the part. I used just some drawings and schematics to figure out measurements and let the shroud calculator do the rest. After a first trial, which turned out to be a little too coarse in shape, I ended up with six rings which created a nice bell-like shape quite similar to the Soyuz. I am really happy with the shape.

Now at first I planned to try and make this a model I could share but that is a couple of steps too far right now. Story time!

My top drawing of the Soyuz capsule trying to locate all the elements.
The biggest problem was getting all the openings and hatches in the hull at about the right place. Most of them take place over more than two rings. And I had a bit of trouble aligning them all after transferring the shapes on to the next prototype.  I need to get the placement of all the portholes, panels and hatches right. I do not have that much reference to get it completely right, even though I have a busload of pictures.

I had to rely on eye-balling and common sense. Not that sure about it all but I guess in the end it will resemble a Soyuz capsule closely enough to be believable… I have never seen a returned Soyuz capsule in paper before, so this might be a first.
My modelling friend Zoltan from Hungary has made a big Soyuz spacecraft in a large scale but his one is in orbital configuration, meaning it's clad in green thermal cloth. This is all gone and burnt off when the capsule re-enters the atmosphere. It leaves the metal skin of the capsule bare. Lots of hatches, panels an other stuff to be seen on the surface.

I have to build two reaction control thruster panels, two small portholes, an opened parachute hatch, a still closed hatch for the reserve parachute and several small hatches for antennae. Then there is the umbilical panel. Above it, the hole that housed the periscope. Above that, there is a bulge that houses the third reaction control thruster set. On top is the crew access hatch.

The bottom part of the capsule is of course the heat shield, but this is jettisoned after the capsule has passed the fiery part of the return and begins its descent through several parachute stages. The revealed bottom under the heat shield houses an altimeter, six braking rockets and three antenna hatches, one of which will open on the ground in case the capsule lands on its side. Also, there is a lot of instructional text on the bottom. In both Cyrillic and English.

So you see, lots to do to get the capsule look right. Hopefully I’ll master it step by step so I can complete this build and place a good looking capsule on the deck of the Zil.

First try. Crude shape. But on the right track.
Second try. Right shape. Now the opening for the 'chute is too low. And perhaps a tad too large.
I started out with a 2D drawing on paper. tried to get the outline of the bell shape right. First try was well on the way but not quite there yet. Try 2 was the right shape. Now I wanted to get all the panel, porthole and hatch stuff drawn on the capsule. After I did this, I carefully disassembled the model and glued it back on a copy of the print I designed. Now for some obscure reason they didn’t align well when I made test 3. I took some time off off the project for some plane stuff and building the rest of the Zil. A couple of days ago, I picked the Soyuz up again and I redrew the capsule, printed a new version and glued it together. I was still happy about it, it has a really good shape.
The paper I use is heavy hobby paper, I bought a whole pile of it in all kinds of bright colours in a thrift shop. It has been used in kindergarten schools and has prints on it but it is perfectly usable for these kinds of things. I'l paint it in the end anyway.

The first layer of paint already improves the look.
And it fits the Zil very well.
I first thought about building the final one out of sandpaper to mimic the pocked and scorched surface. But the trials with that gave a nice result but the sandpaper was hard to cut and I foresaw trouble with the holes I had to cut. So I took this model and build it further to become the final model. I’ll use paint with fine grained sand to create the scorched and burnt-up effects.
Using a couple of dozen pictures of the landed capsule I collected, I tried again to get the right place for all the hatches, portholes and whatnots right. I think I have it drawn out quite accurately now on the hull itself. Silly, I couldn’t find a good all-round view scheme of the Soyuz return capsule on the web.
Anyway, Next step was to carefully cut the holes to create the necessary openings for chute, antenna, umbilical, periscope and all of the other stuff.

Umbilical [U], periscope [PS} and next to that some RCS thrusters.
So with the drawing I made I tried as good as I could to locate the places of the hatches and openings in the hull. Using the seam for the open chute hatch to get rid of most of it.
Here you can see the place where the umbilical panel, the periscope and the RCS thruster will come.

Cutting the first hole. This will be the parachute canister opening. Next thing up was the parachute canister itself. It has a broad metal ring that immediately forms into an oval pocket. I used metallic card for this part.


Getting this angle right was tricky. Still not 100% correct but since only the outside will be seen, I don't care.

Inside this oval pocket, a balloon pushes the parachute out. This balloon remains inside of the pocket. The upper part of the big ring has metal slide guides to get the chute out in one piece. The canister of course houses both ropes on which the Souyuz hangs when the chute is deployed but one of the ropes needs to be on the capsule's other side to stabilize the spacecraft. So there is a trench over the top around the entrance hatch to the other side.

Note the small gap in the ring. This is for the rope to get to the other side. The strips sticking out are belts that probably keep the balloon in place. I don't really know. They're there. That's what is important.

The rope itself was made from twisted yellow paper. I brushed it with thinned PVA glue to make it a little sturdier. The top got a small strip of aluminium tape. The slide guides in the ring were scratch built in one go. Since the capsule is displayed as perepared for transport, the rope is cut. The second rope will be too.

The second rope was built together with a thin white rope I saw on some photos. These ones go over the hull to the other side to have the capsule descend in a more or less upright position.

The capsule will deploy some emergency beacons after landing. These beacons are placed around the top and bottom of the capsule. The one(s) pointing upward  or closest to that position will deploy. They look a bit like fly paper but very sturdy. They are removed before transport and leave these empty openings in the hull.

Before the capsule hits the upper layers of the atmosphere, the crew jettisons the periscope. This is the only device for the commander to look forward while performing docking manoeuvres. They don't need it any more and leaving it on might heavily disrupt the steady airflow around the capsule. After jettisoning is, they're left with a deep hole, that is sealed airtight on the bottom. 

Below the periscope, you can find the umbilical panel. In here all the plugs for operating the engine and service module are located. Power and oxygen are going through these sockets. Now exposed to the elements, it will scorch heavily during the descent.

The first layers of paint are applied to try and get the desired effect of burnt metal, scorchmarks and scratches and scrapings of heat shield debris going past the hull.

A couple of layers later it looks like this: 

And I have to say, I am very happy with how that looks. But we're not there yet. Not yet. I still have a lot to do. I'll leave that for the next time.

Thanks for looking and until next time,

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