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I've read a Russian article based on the recent report by the US Government Accountability Office regarding the NASA Commercial Crew Program. The article claims that it takes three years to order a seat on and to manufacture the Soyuz spacecraft:

Новые места на «Союзах» получать уже поздно — производство корабля и покупка мест занимают примерно три года

Translation:

It is too late to get seats on the "Soyuz" spacecraft -- manufacturing of the vessel and purchasing of the seats take approx. three years

Why does it take so long given the fact that the Soyuz vehicles are old, i. e. that's a proven technology with little, if any, innovation? I thought they were produced in a conveyor-belt-like manner...

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    $\begingroup$ You need very skilled and trained personell to build a reliable spacecraft. To integrate more personell would take time and may endanger quality. The capsule is small, very few technician may work in it simultaneously. Adding manpower to a late project makes it later. $\endgroup$
    – Uwe
    Jul 16, 2018 at 12:06
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    $\begingroup$ @GdD Nor is it true that little to none Innovation is taking place. AFAIK, there are quite a lot of modernisations taking place every so often. $\endgroup$
    – DaGroove
    Jul 16, 2018 at 12:30
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    $\begingroup$ @geoffc, even building 70 you don't use a conveyor belt assembly line. You only do that if you're building thousands. Assembling many at a time is relatively common. $\endgroup$
    – GdD
    Jul 16, 2018 at 13:52
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    $\begingroup$ To highlight the point @DaGroove made, the Soyuz craft has undergone at least five major revisions since its introduction: Soyuz -> Soyuz-T -> Soyuz-TM -> Soyuz-TMA -> Soyuz-TMA-M -> Soyuz-MS (current version) $\endgroup$
    – Tristan
    Jul 16, 2018 at 15:28
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    $\begingroup$ Just so people understand how demanding and time consuming spacecraft manufacture is, a while back, I came across the assembly instructions for the ISS Roller Suspension Unit, a breadbox-sized roller bearing assembly that allows the Mobile Transporter to move along the truss. The assembly instruction book had more than 1,000 pages, and that didn't include the drawings for the individual parts. $\endgroup$
    – Tristan
    Jul 17, 2018 at 14:05

1 Answer 1

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Production of a vehicle taking several years, while 3 to 4 new vehicles being completed every year is the expected behaviour of a "conveyor-belt-like" production method.

On an abstract conveyor belt, each individual item moves to the next station every cycle, and on the end of the conveyor belt, a completed product is also taken off every cycle. However, each individual item takes many cycles from the start of the conveyor belt to the end, proportional to the number of work stations.

This is, I think, the key point of confusion here.

Some other points to address:

Soyuz vehicles are old, i. e that's a proven technology

That does not automatically imply building will be fast. All it means is that repeating what you are doing will keep giving good results.

with little, if any, innovation

This is not true. The Soyuz spacecraft has undergone substantial generational upgrades. At this point, most of the electrical, navigational and docking systems have been replaced at least once.

Finally, what is there to gain by speeding up the process? The current production is able to supply the current demand. Scaling up any production process is costly, and since the demand for Soyuz crafts is fixed, this cost does not justify itself.

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