Author Topic: Soyuz Launcher Transfer Compartment Information (Переходный отсек (ПхО))  (Read 2889 times)

Offline Danderman

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This is what we would call a launch adapter, located at the top of the Soyuz launcher orbital stage, and at the bottom of the payload fairing. It accommodates the launch loads of the payload, as well as serving as the interface between the payload and the upper stage.

As can be seen by the diagrams, the upper propellant tank of the Soyuz orbital stage extends beyond the separation plane; rather than simply add some additional length to the stage, the designers instead made launch adapters that could be customized to each payload type (shown below).   The term for this adapter in English is Transfer Compartment (PKhO) or Intermediate Bay, depending on the payload.  The payload adapter and payload fairing are provided by different companies, per Stan Black, based on payload:

Quote
For Progress and Soyuz spacecraft the PKhO comes from RKTs-Progress, who also produce the Soyuz rocket and fairing too. (So confusing having satellites and factories and rockets all with the same name!) Same also for Resurs-P, Bars-M, Lotos-S, Pion-NKS. Note that an SZB is ordered for these satellites,

http://forum.nasaspaceflight.com/index.php?topic=17286.msg1500874#msg1500874

Lavochkin produce the Fregat upper stage, and it comes with a PKhO. They also produce the narrower fairings used with the Fregat.

https://forum.nasaspaceflight.com/index.php?topic=15064.msg1394949#msg1394949

The 81КС is the large ST-type fairing which is based on article 14С738, the Persona fairing. It is used with the Fregat and is produced by RKTs-Progress.

http://forum.nasaspaceflight.com/index.php?topic=17286.msg1500874#msg1500874

Now to launch Resurs-P № 2 on a Soyuz, it was decided to use the larger 81КС fairing. As that launch did not require a Fregat, which would have come with a PKhO, RKTs-Progress supplied one instead. It was referred to as 196КС.
http://www.samaratoday.ru/img/2014/12/KA-Resurs-P-2.jpg
http://forum.nasaspaceflight.com/index.php?topic=24942.msg1502258#msg1502258

There does not seem to be a single factory index number for these units, and as mentioned above, sometimes the PxO unit is included as part of a payload fairing, and is identified as such rather than as an individual piece. As shown below, the PxO seems to be delivered to the launch site attached to the payload fairing, and then is separated and attached to the bottom of the payload, for later integration with the payload fairing.

The most extreme example of the PxO is the Lavochkin unit used for Fregat, which appears as a large white bucket with a mass of about 400 kg. The more common application is for Soyuz, Progress, and similar Progress plant spacecraft, and the PxO would have a smaller mass.

Perhaps some sharp eyed readers have more information about index numbers and physical characteristics of this under appreciated piece of orbital hardware.

« Last Edit: 03/14/2016 02:05 AM by Danderman »

Offline Stan Black

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This picture was took at TsSKB-Progress on 18th december 2008 by ESA photographer Stéphane Corvaja.

It shows Bloc I of rocket n°76029169. I don't know for which launch it was used.

Offline Stan Black

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Offline Stan Black

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Offline Danderman

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Expanding on the Lavockhin link for Soyuz hardware:

Transfer Compartment (ПхО) provides connection to the  space head block of the upper stage of the launch vehicle and the installation of the nose fairing, as well as the transit of electricity and gas connections of carrier rocket systems, spacecraft and Payload Fairing with systems of vehicle and ground equipment to the UK through transit circuits and gas lines of the carrier rocket. Together with the Payload Fairing,  ПхО  provides security - RBF and spacecraft - from the environment in preparation for the launch and in flight (to reset Payload Fairing).

The Transfer Compartment 14S227.

The Transfer Compartment 14S227 designed and manufactured by  ФГУП «НПО им. С.А.Лавочкина» for use with Payload Fairing produced by  ФГУП «НПО им. С.А.Лавочкина» (Ø 3715 mm, height 8450 mm or 10400 mm) and Soyuz-2.
ПхО mass ≈ 345 kg

The transition compartment РБФСТМ.

The transition compartment is designed and manufactured by ФГУП «НПО им. С.А.Лавочкина» for use with Payload Fairing production of  JSC Progress (TsSKB) (Ø 4110 mm and 11433 mm in length) and Soyuz-2.
ПхО mass ≈ 465 kg
« Last Edit: 03/14/2016 02:09 PM by Danderman »

Offline Danderman

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Here is an image from Energia showing the PxO for Progress M-66.  The question is what do the numbers on this mean, one is clearly the launch vehicle index number, what is the other?
« Last Edit: 03/14/2016 08:28 PM by Danderman »

Offline Danderman

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What are missing are images of the PxO for Obzor and similar sized satellites launched on Soyuz.

Offline Stan Black

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What are missing are images of the PxO for Obzor and similar sized satellites launched on Soyuz.

The current Volga upper stage, Resurs-P, Lotos-S, Pion-NKS, Bion-M and Foton-M are based on the current generation of Yantar derived satellites. Some still feature derivatives of the 11С516 fairing and transfer compartment.

Both Bars-M and Obzor-R are based on the next generation of satellites from RKTs-Progress in Samara.
http://forum.nasaspaceflight.com/index.php?topic=32187.0
http://forum.nasaspaceflight.com/index.php?topic=32725.0

For Bars-M №1 its rocket sits in a block, series with contracts in the 2008-2009 period. The rocket was a Soyuz-2-1a, and because the fairing was specific to Bars-M and had a matching serial number, then it looks like it was not taken from a different satellite.

Though ordered at different times, at the start of production it appears that fairings and rockets have matching internal factory serial numbers (the machine series). Also the military tail numbers starting with a 7 are the same too. This can change though by the time the rocket leaves the factory.
http://forum.nasaspaceflight.com/index.php?topic=37430.msg1441259#msg1441259

But that fairing for Bars-M looked like those used by the Yantar derived predecessors.

My sneaking suspicion is that the rocket started life as Soyuz-2-1b №010; and at that time the payload was to be Yantar derived. Rocket 11М134С was Soyuz-2-1b №009, then follows Soyuz-U and Soyuz-FG, the Bars rocket was 23М134С and 24М134С was Soyuz-2-1b №011.

Likewise the rocket ordered for Obzor-R was also a Soyuz-2-1b. It was part of a contract for three rockets. The other two being for Meteor-M № 2-2 and Arktika-M № 1. Soon after a second contract was placed for two fairings, but not for Obzor-R.
http://forum.nasaspaceflight.com/index.php?topic=17286.msg1500874#msg1500874

The contract for Obzor-R has been amended, and the rocket is to now to be a Soyuz-2-1a. No indication is given as to the type of fairing to be used.
« Last Edit: 03/17/2016 05:14 PM by Stan Black »

Offline Danderman

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Is there any evidence that a specific PxO is always used in conjunction with a specific payload fairing?

And is the Bars-M payload fairing truly unique, or has it been used on earlier launches?

Offline Stan Black

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Is there any evidence that a specific PxO is always used in conjunction with a specific payload fairing?

And is the Bars-M payload fairing truly unique, or has it been used on earlier launches?


Contracts show the 81КС and 14С737 as GO, that is they do not have a PKhO. The PKhO comes with the Fregat upper stage.

Resurs-P is the only example I have seen of a PKhO as a separate item; but see my thoughts here:-
http://forum.nasaspaceflight.com/index.php?topic=24942.120#msg1502258

For Progress and Energia satellites it is always a SZB (a combination of GO and PKhO): 17С13А7, 17С13А8, 11С517А2 and 11С517А3, 14С736, 14С738, 14С741, 14С744.

For Bars-M it shows its heritage, but is so far the only example of that specific article index of 14С744.
« Last Edit: 03/19/2016 10:24 AM by Stan Black »

Offline Danderman

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Progress MS-2 PxO (from Energia.ru)

« Last Edit: 03/25/2016 02:12 PM by Danderman »

Offline Stan Black

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Progress MS-02 PxO (from Energia.ru)

136th Series

Contract №353-1193/12
16М136С (required 2014/06) 14А14-1А Г15000-021 / 11С517А2 Г15000-109
23М136С (required 2014/09) 14А14-1А Г15000-022 / 11С517А2 Г15000-110
36М136С (required 2015/03) 14А14-1А Р15000-023 / 11С517А2 Р15000-111

Contract №353-1130/12
18М136С (required 2014/I) 11А511У-ПВБ Г15000-146 / 11С517А2 Г15000-112
34М136С (required 2014/III) 11А511У-ПВБ Г15000-147 / 11С517А2 Г15000-113
39М136С (required 2015/I) 11А511У-ПВБ Р15000-148 / 11С517А2 Р15000-114

137th Series

Contract №353-1193/12
5М137С (required 2015/09) 14А14-1А Р15000-026 / 11С517А2 Р15000-115

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