Author Topic: Deorbit engines on Soviet reconnaissance satellites  (Read 8141 times)

Offline jcm

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Here's a question I have asked some of you before, but not on this forum (as far as I can tell). What was the deorbit propulsion on the 11F69 and the 11F690 ?

At some point the Zenit spy satellites switched from the Isaev liquid TDU-1 to the solid PTDU 11D82M for its deorbit propulsion. Has anything come to light yet on when that switch was made? There seems to be no consensus on the sites I have looked at. A couple of places (astronautix, nmspacemuseum) cite 104 uses of the TDU-1 but I haven't tracked down a primary source - that would imply just Vostok and Zenit-2 11F61 and a handful of other flights, if true. I think it's clear-ish that the Zenit-4MK and later vehicles used the solid motor, and Zenit-4M probably did; what's less clear to me is which was used by 11F69 Zenit-4 and 11F690 Zenit-2M. My guess would have been 11F69 using the liquid and 11F690 using the solid, but I see a couple of sources claiming 11F69 used the 11D82 solid.

Any takers?

 
 
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Re: Deorbit engines on Soviet reconnaissance satellites
« Reply #1 on: 01/22/2013 09:38 AM »
That Energia picture book of many years ago shows identical rear ends for the Zenit 2 and Zenit 4, no sign of the cover over the retro nozzle that later satellites carried.

Offline B. Hendrickx

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Re: Deorbit engines on Soviet reconnaissance satellites
« Reply #2 on: 01/22/2013 10:59 AM »
Actually, the story is a little more complicated than that. There wasn't one point where they switched from liquid-fuel deorbit engines to solid-fuel deorbit engines. The two types were used simultaneously on different Zenit variants. Novosti Kosmonavtiki forum contributor "Salo" made a list here (updated with new information later on the same page)  :

 http://88.210.62.157/phpBB2/viewtopic.php?t=12501&sid=6191b049305f440ec637bd5864ab9b37

A critical source of information is an online book by Isayev bureau veteran V.S. Zavyalov :

http://zavjalov.okis.ru/file/zavjalov/RabotaVKB.pdf

Another important source of information is an article on the solid-fuel deorbit engines by Igor Afanasyev in Novosti Kosmonavtiki 5/2007, which is not online.

A brief summary :
In the 22 May 1959 government decree that gave the go-ahead for the Vostok programme (the manned and the spy satellite versions) both Isayev's OKB-2 and the NII-125 design bureau of Boris Zhukov were tasked with developing deorbit engines for the various Vostok versions. OKB-2 was to develop a liquid-fuel engine and NII-125 a solid-fuel engine. To speed up things, Korolyov decided to use the liquid-fuel engine both on the manned vehicle and the first spy satellite version (Zenit-2). This engine was initially known as S5.4, but received the military index 8D66 after Zenit-2 was declared operational. Serial production of the engine was turned over by OKB-2 to the Zlatoust Machine Building Factory, where it was manufactured until 1975. In 1974 forty engines were produced with a storage lifetime of 10 years.

It would appear the engine was used by Zenit-2, Zenit-4, Zenit-2M and Zenit-4MKM, which means it saw its last flight with Kosmos-1214 in 1985 . A new Isayev engine (11D452) was introduced on Zenit-6 and a slightly modified version of that (11D452A) flew on Zenit-6U and presumably also on Zenit-8.

When OKB-1 finished the preliminary design for Zenit-4 in 1964, the idea was to introduce the NII-125 solid-fuel engine on the serially produced versions of the satellite. Eventually, the solid-fuel engine made a test flight on Kosmos-69 (a Zenit-4) in June 1965, but it didn't fly again until October 1968 (Kosmos-251, the first Zenit-4M). According to the NK article the solid-fuel engine flew on Zenit-4M, 4MT and 4MK.








Offline jcm

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Re: Deorbit engines on Soviet reconnaissance satellites
« Reply #3 on: 01/22/2013 11:05 AM »
That Energia picture book of many years ago shows identical rear ends for the Zenit 2 and Zenit 4, no sign of the cover over the retro nozzle that later satellites carried.

Ah, good point - although I wonder if the retro cover is a separate issue that came much later. In the 1980s we start seeing two extra debris pieces
ejected to higher apogee at deorbit which I assume are the retro cover halves. I don't see these for, e.g., the 11F692M in the 1970s
(although Bion does seem to have them)  Maybe they were there but too small for 1970s radar tracking.
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Offline jcm

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Re: Deorbit engines on Soviet reconnaissance satellites
« Reply #4 on: 01/22/2013 11:10 AM »
Actually, the story is a little more complicated than that. There wasn't one point where they switched from liquid-fuel deorbit engines to solid-fuel deorbit engines. The two types were used simultaneously on different Zenit variants. Novosti Kosmonavtiki forum contributor "Salo" made a list here (updated with new information later on the same page)  :

 http://88.210.62.157/phpBB2/viewtopic.php?t=12501&sid=6191b049305f440ec637bd5864ab9b37

A critical source of information is an online book by Isayev bureau veteran V.S. Zavyalov :

http://zavjalov.okis.ru/file/zavjalov/RabotaVKB.pdf

Another important source of information is an article on the solid-fuel deorbit engines by Igor Afanasyev in Novosti Kosmonavtiki 5/2007, which is not online.

A brief summary :
In the 22 May 1959 government decree that gave the go-ahead for the Vostok programme (the manned and the spy satellite versions) both Isayev's OKB-2 and the NII-125 design bureau of Boris Zhukov were tasked with developing deorbit engines for the various Vostok versions. OKB-2 was to develop a liquid-fuel engine and NII-125 a solid-fuel engine. To speed up things, Korolyov decided to use the liquid-fuel engine both on the manned vehicle and the first spy satellite version (Zenit-2). This engine was initially known as S5.4, but received the military index 8D66 after Zenit-2 was declared operational. Serial production of the engine was turned over by OKB-2 to the Zlatoust Machine Building Factory, where it was manufactured until 1975. In 1974 forty engines were produced with a storage lifetime of 10 years.

It would appear the engine was used by Zenit-2, Zenit-4, Zenit-2M and Zenit-4MKM, which means it saw its last flight with Kosmos-1214 in 1985 . A new Isayev engine (11D452) was introduced on Zenit-6 and a slightly modified version of that (11D452A) flew on Zenit-6U and presumably also on Zenit-8.

When OKB-1 finished the preliminary design for Zenit-4 in 1964, the idea was to introduce the NII-125 solid-fuel engine on the serially produced versions of the satellite. Eventually, the solid-fuel engine made a test flight on Kosmos-69 (a Zenit-4) in June 1965, but it didn't fly again until October 1968 (Kosmos-251, the first Zenit-4M). According to the NK article the solid-fuel engine flew on Zenit-4M, 4MT and 4MK.



Bart, thank you, that's very helpful. I had forgotten Afanasev's article
and didn't know the other two sources.
I'm really surprised they were using liquid-fuel engines as late as Zenit-8, fascinating.
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Offline jcm

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Re: Deorbit engines on Soviet reconnaissance satellites
« Reply #5 on: 01/22/2013 11:56 AM »
Actually, the story is a little more complicated than that. There wasn't one point where they switched from liquid-fuel deorbit engines to solid-fuel deorbit engines. The two types were used simultaneously on different Zenit variants. Novosti Kosmonavtiki forum contributor "Salo" made a list here (updated with new information later on the same page)  :

 http://88.210.62.157/phpBB2/viewtopic.php?t=12501&sid=6191b049305f440ec637bd5864ab9b37

A critical source of information is an online book by Isayev bureau veteran V.S. Zavyalov :

http://zavjalov.okis.ru/file/zavjalov/RabotaVKB.pdf

Another important source of information is an article on the solid-fuel deorbit engines by Igor Afanasyev in Novosti Kosmonavtiki 5/2007, which is not online.

A brief summary :
In the 22 May 1959 government decree that gave the go-ahead for the Vostok programme (the manned and the spy satellite versions) both Isayev's OKB-2 and the NII-125 design bureau of Boris Zhukov were tasked with developing deorbit engines for the various Vostok versions. OKB-2 was to develop a liquid-fuel engine and NII-125 a solid-fuel engine. To speed up things, Korolyov decided to use the liquid-fuel engine both on the manned vehicle and the first spy satellite version (Zenit-2). This engine was initially known as S5.4, but received the military index 8D66 after Zenit-2 was declared operational. Serial production of the engine was turned over by OKB-2 to the Zlatoust Machine Building Factory, where it was manufactured until 1975. In 1974 forty engines were produced with a storage lifetime of 10 years.

It would appear the engine was used by Zenit-2, Zenit-4, Zenit-2M and Zenit-4MKM, which means it saw its last flight with Kosmos-1214 in 1985 . A new Isayev engine (11D452) was introduced on Zenit-6 and a slightly modified version of that (11D452A) flew on Zenit-6U and presumably also on Zenit-8.

When OKB-1 finished the preliminary design for Zenit-4 in 1964, the idea was to introduce the NII-125 solid-fuel engine on the serially produced versions of the satellite. Eventually, the solid-fuel engine made a test flight on Kosmos-69 (a Zenit-4) in June 1965, but it didn't fly again until October 1968 (Kosmos-251, the first Zenit-4M). According to the NK article the solid-fuel engine flew on Zenit-4M, 4MT and 4MK.


I read the sources a slightly different way - I don't see the phrase 'TDU' used for the 11D452, just 'DU'. Isn't this 11D452 just the nose mounted KDU?

- the NK article mentions the Zenit-4 variants but doesn't talk about -6 and -8 either way.
 - the Zavyalov book, which I just now skimmed so maybe I am missing something, does talk about the 11D452 development and its use on -6 and -8 but doesn't say it was the deorbit engine. He does talk about the 8D66 liquid engine on Zenit-2 and -4, and then goes on to talk about later Zenit variants but in a vague way that I don't find to be a definitive statement that the engine was used on those variants - and maybe it was used as the KDU (manuevering engine) on the later variants, not the deorbit engine. (if you have a liquid deorbit engine, why have a separate manuevering engine?)
 - Sato's NK forum list does agree with my interpretation, talking about the solid TDU and liquid KDU for the later missions, and saying that the Zenit-2M retained the liquid TDU.

so I conclude that the sources are consistent with deorbit engines being

 S5.4 / 8D66 liquid engine  -  Vostok, Zenit-2, Zenit-4 except K69, Zenit-2M


[edit - earlier I typed 8D66M when I meant 11D82M]
  11D82M solid engine - all other variants plus the K-69 test flight

and the nose mounted in-orbit  liquid manuever engine being  8D66 for the early Zenit-4M and 11D452 for Zenit-6 and 8.
« Last Edit: 01/22/2013 12:18 PM by jcm »
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Offline B. Hendrickx

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Re: Deorbit engines on Soviet reconnaissance satellites
« Reply #6 on: 01/22/2013 12:06 PM »
Zavyalov seems to say the 11D452(A) was a replacement for the 8D66, but  he describes it as a restartable engine and it looks like it was only used for orbital corrections, not deorbit. That's also the conclusion the guys on the NK forum reached a little later in the thread I mentioned. It couldn't do both the orbital corrections and the deorbit burn. So it would seem Zenit-6 and 8 had a solid-fuel deorbit engine after all.

Offline jcm

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Re: Deorbit engines on Soviet reconnaissance satellites
« Reply #7 on: 01/22/2013 12:13 PM »
Zavyalov seems to say the 11D452(A) was a replacement for the 8D66, but  he describes it as a restartable engine and it looks like it was only used for orbital corrections, not deorbit. That's also the conclusion the guys on the NK forum reached a little later in the thread I mentioned. It couldn't do both the orbital corrections and the deorbit burn. So it would seem Zenit-6 and 8 had a solid-fuel deorbit engine after all.

OK, so we are in agreement then. Thanks!
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Re: Deorbit engines on Soviet reconnaissance satellites
« Reply #8 on: 01/22/2013 02:27 PM »
That Energia picture book of many years ago shows identical rear ends for the Zenit 2 and Zenit 4, no sign of the cover over the retro nozzle that later satellites carried.

Ah, good point - although I wonder if the retro cover is a separate issue that came much later. In the 1980s we start seeing two extra debris pieces
ejected to higher apogee at deorbit which I assume are the retro cover halves. I don't see these for, e.g., the 11F692M in the 1970s
(although Bion does seem to have them)  Maybe they were there but too small for 1970s radar tracking.
On a quick search, the only Zenit-2M with these pieces was K-1004.  Another one-off like K-69?

Offline Stan Black

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Re: Deorbit engines on Soviet reconnaissance satellites
« Reply #9 on: 01/22/2013 03:53 PM »
so I conclude that the sources are consistent with deorbit engines being

 S5.4 / 8D66 liquid engine  -  Vostok, Zenit-2, Zenit-4 except K69, Zenit-2M

  11D82M solid engine - all other variants plus the K-69 test flight

and the nose mounted in-orbit  liquid manuever engine being  8D66 for the early Zenit-4M and 11D452 for Zenit-6 and 8.

Just to clarify the 8D66 is used at either end?
« Last Edit: 01/22/2013 08:45 PM by Stan Black »

Online Phillip Clark

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Re: Deorbit engines on Soviet reconnaissance satellites
« Reply #10 on: 01/22/2013 04:31 PM »
That Energia picture book of many years ago shows identical rear ends for the Zenit 2 and Zenit 4, no sign of the cover over the retro nozzle that later satellites carried.

Ah, good point - although I wonder if the retro cover is a separate issue that came much later. In the 1980s we start seeing two extra debris pieces
ejected to higher apogee at deorbit which I assume are the retro cover halves. I don't see these for, e.g., the 11F692M in the 1970s
(although Bion does seem to have them)  Maybe they were there but too small for 1970s radar tracking.
On a quick search, the only Zenit-2M with these pieces was K-1004.  Another one-off like K-69?


Alternatively, debris was not catalogued as routinely in those early years as it was in the 1980s onwards.   So the debris might have been there, tracked even, but never put in the public catalogue.
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Offline B. Hendrickx

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Re: Deorbit engines on Soviet reconnaissance satellites
« Reply #11 on: 01/22/2013 08:49 PM »

 - the Zavyalov book, which I just now skimmed so maybe I am missing something, does talk about the 11D452 development and its use on -6 and -8 but doesn't say it was the deorbit engine. He does talk about the 8D66 liquid engine on Zenit-2 and -4, and then goes on to talk about later Zenit variants but in a vague way that I don't find to be a definitive statement that the engine was used on those variants - and maybe it was used as the KDU (manuevering engine) on the later variants, not the deorbit engine. (if you have a liquid deorbit engine, why have a separate manuevering engine?)

I doesn't look like the 8D66 could be used for orbit corrections. I've seen no evidence that it had restart capability. Let's also compare the parameters of the 8D66 (or to be more exact the S5.4 flown on the manned Vostok vehicles) with those of the Resurs-F1M orbit correction engine (which must have been similar to that used on the Zenits) :

S5.4 :
thrust : 1.614 tons
specific impulse : 266 s
propellants : TG-02/AK-27I
equipped with turbopump

Resurs-F1M engine :
thrust : 300 kg
specific impulse : 290 s
propellants : UDMH/AK-27I
pressure-fed

Zavyalov specificially says the Zenit-4MKM ("Gerakl") was equipped with the 8D66. If that is true, it could only have been used as a deorbit engine. That would mean it had a liquid-fuel deorbit engine on one end and a liquid-fuel orbit correction engine on the other. By the way, the last Zenit-4MKM flight (Kosmos-1214) was in 1980, not in 1985 as I said in my earlier post.

This does raise the question why the Zenit-4MKM would have needed a liquid-fuel deorbit engine and the other Zenit-4M variants a solid-fuel deorbit engine. Of course, Zavyalov may have made a mistake.

Offline Stan Black

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Re: Deorbit engines on Soviet reconnaissance satellites
« Reply #12 on: 01/22/2013 09:01 PM »
Is there also any connection to the additional engine on Voskhod?

Offline jcm

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Re: Deorbit engines on Soviet reconnaissance satellites
« Reply #13 on: 01/22/2013 10:32 PM »


Zavyalov specificially says the Zenit-4MKM ("Gerakl") was equipped with the 8D66. If that is true, it could only have been used as a deorbit engine. That would mean it had a liquid-fuel deorbit engine on one end and a liquid-fuel orbit correction engine on the other. By the way, the last Zenit-4MKM flight (Kosmos-1214) was in 1980, not in 1985 as I said in my earlier post.

This does raise the question why the Zenit-4MKM would have needed a liquid-fuel deorbit engine and the other Zenit-4M variants a solid-fuel deorbit engine. Of course, Zavyalov may have made a mistake.


Yes, the reference to "Gerakl 11F692M/Zenit-4MKM with DU 8D66" on page 109 is quite specific. Hmm.. my hunch is that it's a mistake and that he's referring to the orbit correction engine - maybe somehow it was considered a derivative of the 8D66 despite different design.
But it would be nice to find other sources to confirm or refute this. So I guess we have to leave the question open for now.
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Offline B. Hendrickx

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Re: Deorbit engines on Soviet reconnaissance satellites
« Reply #14 on: 01/22/2013 11:42 PM »
Is there also any connection to the additional engine on Voskhod?

Like the Zenit solid-fuel deorbit engines, the Voskhod back-up solid-fuel deorbit engine was developed by NII-125, but it seems to have been built specifically for Voskhod. Its designator was 15Kh13. Here is the most detailed description I can find :

http://www.ugresh.ru/uv/newarxiv.htm/?act=viewtopic&idgod=2007&idnomer=40&topic=2207

No indication here of a link with the 11Д82 Zenit solid-fuel engine. It's mentioned in passing in the NK 5/2007 article on the solid-fuel Zenit engines, where it said to have been of a much simpler design than the Zenit engine. The article wrongly says the Zenit engine flew before the Voskhod engine. The 15Kh13 flew on Kosmos-47 (October 1964), Voskhod-1  (October 1964) and Voskhod-2 (March 1965) before the 11D82 made its debut on Kosmos-69 (June 1965).

Offline Stan Black

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Re: Deorbit engines on Soviet reconnaissance satellites
« Reply #15 on: 01/27/2013 09:19 PM »
This contains some diagrams of the engine and cover

http://wsn.spaceflight.esa.int/docs/EuropeanUserGuide/chapter_6_foton.pdf

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Re: Deorbit engines on Soviet reconnaissance satellites
« Reply #16 on: 02/01/2013 03:11 AM »
This contains some diagrams of the engine and cover

http://wsn.spaceflight.esa.int/docs/EuropeanUserGuide/chapter_6_foton.pdf


That's really nice! Thanks for that link
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Re: Deorbit engines on Soviet reconnaissance satellites
« Reply #17 on: 02/01/2013 03:17 AM »

So a new but related question - in 1973-75 the Yantar small film capsules were test flown on Gektor satellites as "FEU-170".

The Yantar history in Novosti Kosmonavtiki tells us FEU-170 was mounted on the Zenit-2M's nose in place of the Nauka capsule, and the experiment involved recovery of the SpK capsule.

What's not entirely clear to me: did this test include test of the 11D864 deorbit motor, with FEU-170 separation and deorbit one or more orbits before recovery of the main Zenit-2M satellite? Or was it just a test of the SpK heat shield and parachute system with separation of the capsule from the Zenit-2M after the Zenit-2M's deorbit burn?

Also, what is the object that remained in orbit after recovery? Some kind of cover for the FEU-170? or an attach device?
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Re: Deorbit engines on Soviet reconnaissance satellites
« Reply #18 on: 02/01/2013 12:28 PM »
Iíve corresponded about the Zenit deorbit engines with Isayev bureau veteran Vladimir Zavyalov. He told me that only  TsSKB historians can give accurate answers to my questions, but  he did give me some interesting information.

Zavyalov thinks the 11D82(M) solid-fuel deorbit engine was used as a back-up to the Isayev bureauís liquid-fuel 8D66. Initially, Korolyov wanted to have a prime and back-up deorbit engine on the manned Vostoks and the early Zenits, but the payload capacity of the Vostok rocket didnít make that possible. However, as the Vostok launch vehicle was replaced by the more capable Voskhod and Soyuz rockets, it became possible to increase the mass of the Zenits from 4700-4740 kg to 6300 kg and install the back-up solid fuel deorbit engine.

I then asked him how the Zenits could maneuver if they had deorbit engines on both ends. After all, the 8D66 does not have restart capability (as he confirmed to me).  I also asked him why the back-up deorbit capability was needed on the Zenits. If the deorbit burn failed, the Zenit would presumably activate a self-destruct system on re-entry to make sure that the descent capsule didnít end up on foreign territory. The photographic material would have been lost, but given the high launch rate of the Zenits that should not have been catastrophic if it happened only occasionally.

Zavyalov answered that the back-up capability was needed to make sure that the expensive cameras returned to Earth and could be reused on later satellites. He said that the maneuvers may have been carried out with the gas thrusters of the attitude control system. The early Zenits had two sets of 8 thrusters each (with a thrust of 1.2 kg) that were installed on the service module. These were used to orient the satellites for photography and also to position them for the deorbit burn. As the Zenits switched to more capable launch vehicles, the number of gas thrusters was increased and this Ėaccording to Zavyalov- could have made it possible to use them in addition for small orbit corrections.

Zavyalov also says that about 600 8D66 engines were produced by the Zlatoust Machine Building Factory and that not a single one ever failed in flight.

He says that Zenits-6 and 8 did not carry the 8D66, but the 11D452, which could be used both for orbit corrections and the deorbit burn. He doesnít know whether these satellites carried a solid-fuel (backup) deorbit engine.

The Yantar series also carried a single engine (11D430 and further modifications) both for orbit corrections and deorbit. The engines had a built-in capability to do a 300-second deorbit burn in addition to the orbital maneuvers.

Thatís all the information I got from Zavyalov. I doubt if it all stands up to scrutiny. I remain skeptical about the back-up role of the 11D82(M). For one, by all accounts the maneuverable Zenits discarded the front-mounted engine unit prior to the deorbit burn. How do you explain that if it was intended solely for deorbit? Also, the Resurs-F satellites clearly had an aft-mounted solid-fuel deorbit engine and a front-mounted liquid-fuel  orbit correction engine that must have been inherited from Zenit ( I mentioned that in my correspondence with Zavyalov, but he didnít respond to that). And could the kind of maneuvers performed by the Zenit-4M family have been carried out with a simple set of attitude control thrusters?

One way to check his information about the Zenit-6/8 series is to see whether they left any debris in orbit prior to the deorbit burn. If not, that would indeed confirm that the satellites had a single engine both for orbit corrections and deorbit.

If, as Zavyalov says, about 600 8D66 engines were built, then itís hard to imagine they all actually flew. My count for Zenits other than Zenits-6 and 8 is less than 500.   

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Re: Deorbit engines on Soviet reconnaissance satellites
« Reply #19 on: 02/01/2013 12:47 PM »
One way to check his information about the Zenit-6/8 series is to see whether they left any debris in orbit prior to the deorbit burn.
They indeed did.

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Re: Deorbit engines on Soviet reconnaissance satellites
« Reply #20 on: 02/01/2013 10:16 PM »
 I'm trying to get my head around this. The 8D66 was at the rear for Zenit. A backup was added; the solid propellant 11D82. But would the 8D66 have remained at the rear? The 11D82 at the front? If it was always the plan from the days of Vostok, why does Voskhod feature a different solid propellant unit?

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Re: Deorbit engines on Soviet reconnaissance satellites
« Reply #21 on: 02/01/2013 11:57 PM »
One way to check his information about the Zenit-6/8 series is to see whether they left any debris in orbit prior to the deorbit burn.
They indeed did.

That would mean Zavyalov is wrong and the most likely scenario is that the 11D452 was only used for orbital corrections and discarded prior to the deorbit burn, which was performed by an aft-mounted solid-fuel engine.

In his online book Zavyalov gives a propellant mass of 250 kg for the 11D452. The 8D66, solely used for deorbit, had a propellant mass of 280 kg. 250 kg was hardly enough both for orbit corrections and deorbit.

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Re: Deorbit engines on Soviet reconnaissance satellites
« Reply #22 on: 02/02/2013 12:08 AM »
 I'm trying to get my head around this. The 8D66 was at the rear for Zenit. A backup was added; the solid propellant 11D82. But would the 8D66 have remained at the rear? The 11D82 at the front? If it was always the plan from the days of Vostok, why does Voskhod feature a different solid propellant unit?

Again, the information provided by Zavyalov should be treated with caution. The most likely scenario still is that the Zenits flew with either the 8D66 or the 11D82 deorbit engine, not with both at the same time. This is also confirmed in this book on Zenit, where it is said that the solid-fuel deorbit engine eventually replaced the liquid-fuel deorbit engine :
 
С. И. Королев, Н.К. Матвеев. Космические аппараты серии Зенит

epizodsspace.no-ip.org/bibl/korolev-s/zenit.doc
 

Offline jcm

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Re: Deorbit engines on Soviet reconnaissance satellites
« Reply #23 on: 02/03/2013 01:05 AM »
I'm trying to get my head around this. The 8D66 was at the rear for Zenit. A backup was added; the solid propellant 11D82. But would the 8D66 have remained at the rear? The 11D82 at the front? If it was always the plan from the days of Vostok, why does Voskhod feature a different solid propellant unit?

Again, the information provided by Zavyalov should be treated with caution. The most likely scenario still is that the Zenits flew with either the 8D66 or the 11D82 deorbit engine, not with both at the same time. This is also confirmed in this book on Zenit, where it is said that the solid-fuel deorbit engine eventually replaced the liquid-fuel deorbit engine :
 
С. И. Королев, Н.К. Матвеев. Космические аппараты серии Зенит

epizodsspace.no-ip.org/bibl/korolev-s/zenit.doc
 


One of the biggest challenges of historical research is the confident statements made by people who were there at the time and remember what happened in great detail but completely wrongly. I've come across this talking to US CORONA veterans too - for example, that  A happened so then they did B, when in fact we know very well that B happened 2 years before A. This is why you really need both contemporary documents and modern reminiscences.

With all respect to Zavyalov's status as a participant, I think he has to be wrong.


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Offline Stan Black

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Re: Deorbit engines on Soviet reconnaissance satellites
« Reply #24 on: 02/03/2013 06:55 PM »
 Remember reading somewhere Voskhod had additional solid propellant soft-landing engines under the parachute lines? Did any of the Zenit derivatives feature something similar?

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Re: Deorbit engines on Soviet reconnaissance satellites
« Reply #25 on: 02/03/2013 09:12 PM »
One of the biggest challenges of historical research is the confident statements made by people who were there at the time and remember what happened in great detail but completely wrongly. I've come across this talking to US CORONA veterans too - for example, that  A happened so then they did B, when in fact we know very well that B happened 2 years before A. This is why you really need both contemporary documents and modern reminiscences.

With all respect to Zavyalov's status as a participant, I think he has to be wrong.

Yes, memories are fallible... By the way, Zavyalov may not have been personally involved in the development of the Zenit deorbit engines. The Isayev bureau worked on a wide array of projects.

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Re: Deorbit engines on Soviet reconnaissance satellites
« Reply #26 on: 02/03/2013 09:21 PM »
 Remember reading somewhere Voskhod had additional solid propellant soft-landing engines under the parachute lines? Did any of the Zenit derivatives feature something similar?

In a document written by Korolyov (published in "The Creative Legacy of Academician S.P. Korolyov") it is said that the Voskhod soft-landing engine was supposed to reduce touchdown speed from 8-10 m/s to 0-2 m/s.

In the Zenit book I mentioned in an earlier post the Zenit landing sequence is described in some detail and there is no mention of a soft-landing engine. The parachute system was designed to enable a touchdown speed of 10 to 12 m/s, which was said to be sufficient to ensure the re-usability of the photographic equipment and the descent capsule itself.

Offline Stan Black

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Re: Deorbit engines on Soviet reconnaissance satellites
« Reply #27 on: 02/03/2013 09:55 PM »

So a new but related question - in 1973-75 the Yantar small film capsules were test flown on Gektor satellites as "FEU-170".

The Yantar history in Novosti Kosmonavtiki tells us FEU-170 was mounted on the Zenit-2M's nose in place of the Nauka capsule, and the experiment involved recovery of the SpK capsule.

What's not entirely clear to me: did this test include test of the 11D864 deorbit motor, with FEU-170 separation and deorbit one or more orbits before recovery of the main Zenit-2M satellite? Or was it just a test of the SpK heat shield and parachute system with separation of the capsule from the Zenit-2M after the Zenit-2M's deorbit burn?

Also, what is the object that remained in orbit after recovery? Some kind of cover for the FEU-170? or an attach device?

Well that recent publication says

Quote
Спуск капсулы ФЭУ-170 № 1 был осуществлен 08.10.73

САМАРСКИЕ СТУПЕНИ ęСЕМЕРКИĽ

And the rest came down on the 9th?

http://www.zarya.info/Diaries/Zenit/Zenit-2M.php

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Re: Deorbit engines on Soviet reconnaissance satellites
« Reply #28 on: 02/04/2013 05:05 AM »

So a new but related question - in 1973-75 the Yantar small film capsules were test flown on Gektor satellites as "FEU-170".

The Yantar history in Novosti Kosmonavtiki tells us FEU-170 was mounted on the Zenit-2M's nose in place of the Nauka capsule, and the experiment involved recovery of the SpK capsule.

What's not entirely clear to me: did this test include test of the 11D864 deorbit motor, with FEU-170 separation and deorbit one or more orbits before recovery of the main Zenit-2M satellite? Or was it just a test of the SpK heat shield and parachute system with separation of the capsule from the Zenit-2M after the Zenit-2M's deorbit burn?

Also, what is the object that remained in orbit after recovery? Some kind of cover for the FEU-170? or an attach device?

Well that recent publication says

Quote
Спуск капсулы ФЭУ-170 № 1 был осуществлен 08.10.73

САМАРСКИЕ СТУПЕНИ ęСЕМЕРКИĽ

And the rest came down on the 9th?

http://www.zarya.info/Diaries/Zenit/Zenit-2M.php

Ah, very interesting. My reconstruction indicates Kosmos-596
landed at about 0745 UTC on Oct 9; the descent of the FEU-170 would then probably have been at around 0730 UTC (deorbit) 0755 UTC (approx touchdown) on Oct 8 (or possibly one orbit later), and the inference of
coming down on different days is that the FEU-170 did indeed include the little solid deorbit motor.

I'd love to see a TsSKB drawing or photo of the FEU-170 attached to
the Zenit-2M !
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Offline Nicolas PILLET

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Re: Deorbit engines on Soviet reconnaissance satellites
« Reply #29 on: 03/17/2014 05:56 PM »
Remember reading somewhere Voskhod had additional solid propellant soft-landing engines under the parachute lines? Did any of the Zenit derivatives feature something similar?

In a document written by Korolyov (published in "The Creative Legacy of Academician S.P. Korolyov") it is said that the Voskhod soft-landing engine was supposed to reduce touchdown speed from 8-10 m/s to 0-2 m/s.

In the Zenit book I mentioned in an earlier post the Zenit landing sequence is described in some detail and there is no mention of a soft-landing engine. The parachute system was designed to enable a touchdown speed of 10 to 12 m/s, which was said to be sufficient to ensure the re-usability of the photographic equipment and the descent capsule itself.

The question of soft landing engines for Sharik-type satellites is not clear to me. I think that there is soft-landing on Bion and Foton, but I'm not sure. I've took these pictures in Samara, which make me think that the answer is "Yes, there are soft landing engines under the parachute"...

Foton-8 :
http://www.kosmonavtika.com/satellites/foton/visite/08/fig4-3.jpg

Bion-10 :
http://www.kosmonavtika.com/satellites/bion/visite/10/fig5-1.jpg
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Re: Deorbit engines on Soviet reconnaissance satellites
« Reply #30 on: 03/18/2014 07:38 AM »
This contains some diagrams of the engine and cover

http://wsn.spaceflight.esa.int/docs/EuropeanUserGuide/chapter_6_foton.pdf

Most of the drawings in that document are mine, I did the illustration job for the whole ESA's Microgravity Platform Handbook back in 2005....

P.S. I spent a whole working week inside a real Foton reentry capsule (hosted inside the ERASMUS Center) taking photos and handmade drawing to realize the technical tables.

Ciao
Giuseppe
« Last Edit: 03/18/2014 10:37 AM by archipeppe68 »

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Re: Deorbit engines on Soviet reconnaissance satellites
« Reply #31 on: 04/21/2014 06:42 PM »
Remember reading somewhere Voskhod had additional solid propellant soft-landing engines under the parachute lines? Did any of the Zenit derivatives feature something similar?

In a document written by Korolyov (published in "The Creative Legacy of Academician S.P. Korolyov") it is said that the Voskhod soft-landing engine was supposed to reduce touchdown speed from 8-10 m/s to 0-2 m/s.

In the Zenit book I mentioned in an earlier post the Zenit landing sequence is described in some detail and there is no mention of a soft-landing engine. The parachute system was designed to enable a touchdown speed of 10 to 12 m/s, which was said to be sufficient to ensure the re-usability of the photographic equipment and the descent capsule itself.

In this page, it is written that Kobalt had Soyuz-like gamma-altimeter :

http://caves.ru/threads/34180-%D0%9E%D0%B1%D1%81%D1%83%D0%B6%D0%B4%D0%B5%D0%BD%D0%B8%D0%B5-%D0%BE%D0%BF%D0%B0%D1%81%D0%BD%D1%8B%D1%85-%D0%BD%D0%B0%D1%85%D0%BE%D0%B4%D0%BE%D0%BA/page68

So, it would mean that Kobalt had soft-landing engines, since the gamma-altimeter's role is to ignite them...
Nicolas PILLET
Kosmonavtika : The French site on Russian Space

Offline Stan Black

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Re: Deorbit engines on Soviet reconnaissance satellites
« Reply #32 on: 04/21/2014 08:15 PM »
Remember reading somewhere Voskhod had additional solid propellant soft-landing engines under the parachute lines? Did any of the Zenit derivatives feature something similar?

In a document written by Korolyov (published in "The Creative Legacy of Academician S.P. Korolyov") it is said that the Voskhod soft-landing engine was supposed to reduce touchdown speed from 8-10 m/s to 0-2 m/s.

In the Zenit book I mentioned in an earlier post the Zenit landing sequence is described in some detail and there is no mention of a soft-landing engine. The parachute system was designed to enable a touchdown speed of 10 to 12 m/s, which was said to be sufficient to ensure the re-usability of the photographic equipment and the descent capsule itself.

In this page, it is written that Kobalt had Soyuz-like gamma-altimeter :

http://caves.ru/threads/34180-%D0%9E%D0%B1%D1%81%D1%83%D0%B6%D0%B4%D0%B5%D0%BD%D0%B8%D0%B5-%D0%BE%D0%BF%D0%B0%D1%81%D0%BD%D1%8B%D1%85-%D0%BD%D0%B0%D1%85%D0%BE%D0%B4%D0%BE%D0%BA/page68

So, it would mean that Kobalt had soft-landing engines, since the gamma-altimeter's role is to ignite them...

http://novosti-kosmonavtiki.ru/forum/messages/forum9/topic11293/message857911/#message857911

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