Zvezda shape

[mmeijeri]

I'm curious about the reasons for the irregular shape of Zvezda. It has two cylindrical sections of different diameter. I've been wondering about the reasons for that. I'm sure form follows function, at least to a degree. I can think of a number of reasons. For one, the solar panels need to be stowed somewhere during launch. The shape of the Proton fairing probably also is a factor. And maybe some components were reused from earlier designs.

It would be great to get some authoritative interpretation, but failing that, informed speculation or even armchair punditry would be most welcome.

[Galactic Penguin SST]

I'm curious about the reasons for the irregular shape of Zvezda. It has two cylindrical sections of different diameter. I've been wondering about the reasons for that. I'm sure form follows function, at least to a degree. I can think of a number of reasons. For one, the solar panels need to be stowed somewhere during launch. The shape of the Proton fairing probably also is a factor. And maybe some components were reused from earlier designs.

It would be great to get some authoritative interpretation, but failing that, informed speculation or even armchair punditry would be most welcome.

Well Zvezda is the latest in the DOS series lineage (it's DOS-8), and of course its shape comes from the military Almaz space station program. Which begs the question of why the Almaz stations (Salyut 2/3/5) was designed in such a way....

[mmeijeri]

It's also interesting to compare it to Zarya, which looks much more regular.

[mmeijeri]

Launch capacity of Proton (including earlier versions) and center of mass issues are two other potential explanations that come to mind.

[360-180]

Under fairing left Zvezda , center MLM (FGB), right next generation SPM

Reasons for reducing the diameter of the middle:
Solar arrays were under the payload fairing. See SСБ
Zvezda and FGB modules consists of several pressurized compartments

[Danderman]

The original Almaz design required a large work space to house a telescope, and therefore, Proton prop tanks were modified to serve as the basis for the large work compartment.

Since Proton could not lift an entire station with the 4.1 meter diameter of the large work compartment, to provide some additional work space, a second, smaller compartment was added, based on UR-200 tankage, at 2.9 meters diameter.

 

[mmeijeri]

Thanks guys! Interesting to see how decisions made so long ago still have an impact today.

[Danderman]

Thanks guys! Interesting to see how decisions made so long ago still have an impact today.

This is a photo of moi with Anatoly Karpov, the engineer who drafted the first iteration of the Almaz platform (not the designer at the time, just the draftsman). We were inside an Almaz platform as he was explaining this to me.

[Patchouli]

The original Almaz design required a large work space to house a telescope, and therefore, Proton prop tanks were modified to serve as the basis for the large work compartment.

Since Proton could not lift an entire station with the 4.1 meter diameter of the large work compartment, to provide some additional work space, a second, smaller compartment was added, based on UR-200 tankage, at 2.9 meters diameter.

 

I never knew Soviet stations were derived from propellant tanks I always thought that was just a US thing.

The rest of it I guess is kinda like how the Shuttle drove the size and shape of ISS modules.
I wonder if the ISS form factor will ever be used again like the Almaz or will a new form factor take it's place?

[Ronsmytheiii]

The rest of it I guess is kinda like how the Shuttle drove the size and shape of ISS modules.
I wonder if the ISS form factor will ever be used again like the Almaz or will a new form factor take it's place?

While it is true that the diameter of the shuttle's payload bay determined the usos diameter, modules could have been larger but for upmass limits, the docking module, and no need for the extra rack volume.  Remember that freedom lab/hab modules would have been much larger as the orbiter would go to a lower inclination and used an internal airlock still.

Leftover ISS modules maybe used for a Lagrange gateway station, and the fairings for EELV are pretty much PLB dimensions anyhow (shuttle>Titan IV> Delta IV)

[baldusi]

Well, it will depend a lot on where the next space station is. What I've seen from the Russians, is that they haven't developed a 5m fairing, even for commercial payloads. Since until last year, the only realistic choices for GTO where Ariane 5 (which uses the equivalent to a 4m fairing under the SLYDAS), Proton and Sea Launch, there was no point on making a 4.6m satellite if that meant only riding on the top of Ariane 5. Technically, H-2A, Delta IV and Atlas V do offer 5m, but they are priced out of the launch market.
But now that Falcon 9 is entering the market, and Atlas V is going to offer dual manifesting (which might make a 551 a competitor to Ariane 5), the Russians might have to develop a 5m fairing for Angara.
Thus, it might happen that if they have a 5m fairing available on an Angara 5 or even 7, the next Russian "main" module might look different. But if you ask me, the real issue is tooling. Unless they have tooling that big, they won't do anything bigger than 4.1.

[Danderman]

But now that Falcon 9 is entering the market, and Atlas V is going to offer dual manifesting (which might make a 551 a competitor to Ariane 5), the Russians might have to develop a 5m fairing for Angara.
Thus, it might happen that if they have a 5m fairing available on an Angara 5 or even 7, the next Russian "main" module might look different. But if you ask me, the real issue is tooling. Unless they have tooling that big, they won't do anything bigger than 4.1.

The real issue is shipping payload fairings from Moscow to Vostochny, where there is a hard constraint of about 3.8 meters, due to railroad tunnels.

If Russia continues to use Baikonur, the hard constraint from railroad transportation would continue to be 4.1 meters.

[baldusi]

But now that Falcon 9 is entering the market, and Atlas V is going to offer dual manifesting (which might make a 551 a competitor to Ariane 5), the Russians might have to develop a 5m fairing for Angara.
Thus, it might happen that if they have a 5m fairing available on an Angara 5 or even 7, the next Russian "main" module might look different. But if you ask me, the real issue is tooling. Unless they have tooling that big, they won't do anything bigger than 4.1.

The real issue is shipping payload fairings from Moscow to Vostochny, where there is a hard constraint of about 3.8 meters, due to railroad tunnels.

If Russia continues to use Baikonur, the hard constraint from railroad transportation would continue to be 4.1 meters.

I thought that the Proton fairing is transported in four parts, with two being permanently fixed and the other two getting the separation hardware. So it shouldn't be a showstopper. And satellites are normally transported on AN-124, anyways, so it shouldn't add any cost there.
But I still thing that if even Alphasat is a 3.7m architecture, 4.6m satellites are not going to get much more popular.

[Prober]

But now that Falcon 9 is entering the market, and Atlas V is going to offer dual manifesting (which might make a 551 a competitor to Ariane 5), the Russians might have to develop a 5m fairing for Angara.
Thus, it might happen that if they have a 5m fairing available on an Angara 5 or even 7, the next Russian "main" module might look different. But if you ask me, the real issue is tooling. Unless they have tooling that big, they won't do anything bigger than 4.1.

The real issue is shipping payload fairings from Moscow to Vostochny, where there is a hard constraint of about 3.8 meters, due to railroad tunnels.

If Russia continues to use Baikonur, the hard constraint from railroad transportation would continue to be 4.1 meters.

ahhhh its the tunnels.   Thought the Russian rail was smaller to carry the load.   Does anyone know how many tunnels would need to be upgrades.   Might be an interesting story.

[360-180]

What I've seen from the Russians, is that they haven't developed a 5m fairing, even for commercial payloads.

http://www.federalspace.ru/main.php?id=17&oid=24

Диаметр / длина используемых ГО, м
   

4.35 / 11.6 (РБ “Бриз-М”)

4.35 / 15.255 (РБ “Бриз-М”)

5.10 / 16.371 (РБ “Бриз-М”)

5.10 / 19.65 (КВРБ)

4.35 / 12.65 (низкоорбитальный модуль)

[baldusi]

What I've seen from the Russians, is that they haven't developed a 5m fairing, even for commercial payloads.

http://www.federalspace.ru/main.php?id=17&oid=24

Диаметр / длина используемых ГО, м
   

4.35 / 11.6 (РБ “Бриз-М”)

4.35 / 15.255 (РБ “Бриз-М”)

5.10 / 16.371 (РБ “Бриз-М”)

5.10 / 19.65 (КВРБ)

4.35 / 12.65 (низкоорбитальный модуль)

It's been on ILC's guides for ages. I'll consider it a reality when I actually see a mission using it.

[360-180]

What I've seen from the Russians, is that they haven't developed a 5m fairing, even for commercial payloads.

It's been on ILC's guides for ages. I'll consider it a reality when I actually see a mission using it.

5m fairings have been developed but no orders for launches with these fairings. If you want to see the fairing in flight, order a large machine. 
http://s002.radikal.ru/i200/1010/fb/55cc033f85be.jpg
http://s016.radikal.ru/i336/1010/e6/a4ea789e1edb.jpg
http://www.khrunichev.ru/img/site/DSC03112sm.jpg

[360-180]

Module with a diameter greater than 4.1 ок 4.35m have a mass greater than that of Proton can lift into orbit   

[Danderman]

Module with a diameter greater than 4.1 ок 4.35m have a mass greater than that of Proton can lift into orbit   

The requirement for a large payload fairing is not for a LEO module, but rather for light GTO payloads with large antennas and solar arrays. In this particular venture, the customer requires volume, not mass.

[360-180]

Yes. of course.
I tried to follow the topic of this thread.

[baldusi]

Module with a diameter greater than 4.1 ок 4.35m have a mass greater than that of Proton can lift into orbit   

That depends on the amount of internal equipment, the might elect to send it "light". And also, on the outer layers. A 4.1m cylinder with some extra .3m of polypropylene can do wonders for radiation shielding. I'm just saying. In any case, the whole issue of bigger fairing was more on Angara's timeframe.

[ace5]

What is the connection between payload fairing diameter and the mass of the payload itself?

[baldusi]

What is the connection between payload fairing diameter and the mass of the payload itself?

Whithin the current topic (i.e. Russian space station modules), there's a certain "density" given the equipment's average weight. And there's also the assumption that it's going to be longer than wider (which seems to be how most of this things are). Thus, wider module -> bigger module -> heavier module.
The fact is that wider cylinders require heavier walls. Thus, it's usually desirable to make the "long". And then there's the actual ergonomics. Make the internal passages bigger than 2m and it's a problem when the astronaut is in the middle and can't reach the walls.
Thus, I assume that a wider module would mean more insulation. Be it because of micrometeorite protection or radiation insulation. There's also the issue of ports. Russian docking ports are "small diameter", at least when compared to the CBM. Since they don't use the ISS Standard Rack either, there's little point for wider interiors. Plus, they already have the 4.1m tooling.
I still believe that a quick and cheap way to make a DSH is to put a nice wall of 0.3m of polypropilene around a stock 4.1m module, cover it in some micrometeorite wall and wrap it into some thermal insulator. That should offer some very useful protection.
But, if they ever want to make use of artificial gravity, they'll need something bigger. I think 6m is the bare minimum internal diameter, but most probably around 15m. But you don't need (or even desire) a 15m wide module. You can just build a ring out of smaller modules. In which case even 2.55m diameter would be desirable.