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(note: the graphics to this paper will be added at a later date)
THE 'BLOCK D' AND 'BLOCK DM' ROCKET STAGES *
Phillip S Clark
The Block D rocket stage was first flown on a Soviet booster in
March 1967 when the Zond/L-1 test-bed Cosmos 146 was placed into
orbit. It has been a standard part of the four stage Proton booster
since that time, although it is now known that the stage was initially
developed as the service module for the 1960s attempt to land a man on
the Moon. Various versions of the Block D have been developed for
past and future missions, and this article will review the history of
the Block D family.
Table 1 provides a summary of the programmes which have used the
four stage Proton booster (here called Proton-4) with the Block D and
Block DM fourth stages.
To avoid confusion over the terms "Soviet" and "Russian" with
their derivatives the acronym FSU (former Soviet Union) will be used
in the remainder of this article.
Naming the Stage
FSU literature started to refer to the fourth stage of the Proton
booster as being the "Block D" in the early 1980s, a designator which
was immediately realised to be anomalous. From descriptions of
labelling the Korolyov Sputnik-Vostok-Soyuz-Molniya family of launch
vehicles it was known that it was normal practice for the rocket
stages to be named in cyrillic alphabetical order and since "D" is the
fifth letter in the cyrillic alphabet the Proton Block D must have
started life as the fifth stage on another FSU launch vehicle.
Confirmation of this hypothesis came when the first FSU
descriptions of the N-1 lunar booster and the FSU manned lunar
programme appeared. The four stage Proton booster used a modified
Chelomei Proton launch vehicle with a new fourth stage added, Block D,
which was transferred from its original application as the fifth stage
of the N-1 lunar booster.
The main engine of the Block D was designed by Mikhail Melnikov
of the Korolyov design bureau, and Vasili Mishin of the same bureau
(now NPO Energiya) has stated that he was in charge of designing the
rocket stage itself. The current chief designer of the Block D
programme is Boris V Cherniatiev.
----------------------------------------------------------------------
* A much-abridged version of this paper was presented at the British
Interplanetary Society's Soviet Astronautics meeting on 12 June 1993.
In addition, the material has been used in the two editions of the
1993 and 1994 editions of Molniya Space Consultancy Report The Proton
Launch Vehicle Family
----------------------------------------------------------------------
FSU literature in the mid-1980s also noted that a modification of
the original Block D, designated Block DM, had been introduced in the
mid-1970s and was still in use. How the Block DM differed from the
Block D was originally not known, but it was generally assumed in the
West that the Block DM had actually replaced the original Block D on
Proton-4 operations.
Description of the Block D and Block DM
The 1985 edition of Cosmomavtika Entsiklopediya edited by
Valentin P Glushko gave the first descriptions of the Block D, and the
basic numerical data are summarised in Table 2 [1].
In addition, tables of cumulative payload and rocket body masses
have been published in FSU literature written or edited by Glushko
[2,3,4] and in 1983 an analysis of the first of these was published
[5,6]. Using the data from the FSU literature it was possible to
obtain the dry masses of the Block D stages when they were used on
deep space missions, the results being shown in Table 3.
The data presented in Tables 2 and 3 can be used to obtain
further figures initially for the Block D and then for the Block DM.
The Block D and DM assemblies comprise four objects: the rocket
stage itself, a casing which surrounds the rocket stage until just
after it separates from the Proton third stage plus two ullage motors.
The ullage motors separate as the main Block D/DM engine is ignited
for the final (or only) time.
Using the figures in Table 2, the propellant mass of the Block D
comes to 14.8 tonnes, leaving an empty stage mass of 2.5 tonnes.
This is far heavier than the calculated Block D masses obtained from
Glushko's figures.
However, one cannot claim that these results are accurate to two
or three significant figures because the total burn time of the Block
D is described as "600 seconds". If this implies an accuracy of +_ 50
seconds then the result of the propellant mass calculation can only
have an accuracy of +_ 1.2 tonnes. While it is probably safe to say
that the Block D propellant mass is close to 15 tonnes, it is
difficult to justify the accuracy in obtaining a dry structure mass of
2,500 kg.
Table 3 shows that the original Block D stages had masses of
about 1,815 kg (+_ 40 kg) through to the end of 1970 and 1,880 kg (+_ 123
kg) from 1971 to 1984. In fact, the masses of the six Block Ds used
for the 1971 and 1973 Mars missions were anomalously low (1,700 kg),
and excluding these gives a post-1971 mean value of 1,940 kg (+_ 85 kg).
The mass of the outer casing is said to be approximately a tonne -
here taken to be 800 kg which is a reasonable figure.
The Block D assembly also carries two ullage rocket motors.
Each ullage motor - designated SOZ by FSU engineers - has a dry mass
of 56 kg and carries a similar amount of propellant [7]. The pair of
laden ullage motors will have a total mass of about 240 kg.
The Block DM differs from the Block D in that it carries its own
control unit atop the standard stage assembly: on the Block D the
spacecraft control unit is linked with the rocket stage's propulsion
system. Looking at the available sketch of the fourth stage casing,
it seems to be designed to simply cover the Block D/DM propellant
tanks, with the engine (simply designated 58 on the Block D, 58M on
the Block DM) protruding below the casing and the Block DM control
unit above the level of the casing. It seems reasonable to assume
that the same casing was used for the Block D missions rather than a
shorter one.
FSU descriptions have noted that the dry mass of the Block DM
assembly is 3,370 kg, and this appears to be a figure which includes
not simply the dry stage but also the outer casing and the two ullage
motors. Since the casing and ullage motors are probably the same for
both the Block D and Block DM, this implies that the dry mass of the
rocket stage is about 2,350 kg.
The results of these calculations are shown in Table 4.
FSU literature has generally given the length of the Block D as
5.5 metres, and this length equates with that from the tip of the
oxidiser tank to the base of the main engine's rocket nozzle.
Propellants for the Block D and Block DM
FSU literature describes the propellants for the Block D and
Block DM as being a liquid oxygen oxidiser and a "hydrocarbon" fuel.
The latter term in FSU literature has normally related to kerosene
which is what the Block D and Block DM actually used.
In the late 1980s the Block DM fuel was varied, one called SYNTIN
being used on some (but not all) missions. SYNTIN has been described
as a "synthetic hydrocarbon of [the] cyclopropane row" on page 5 of
reference 20. FSU references indicate that its use permits the
specific impulse of the Block DM's 58M engine to be increased from 352
seconds to 362 seconds, permitting at least 200 kg additional payload
to be carried to geosynchronous orbit for the same propellant load.
It is not known whether the use of SYNTIN requires modifications to be
made to the standard Block DM assembly.
The liquid oxygen is carried in an approximately spherical
propellant tank at the top of the rocket stage, while the fuel
(kerosene or SYNTIN) is in a torus tank which surrounds the upper part
of the rocket engine assembly.
The first and second engine ignitions performed on geosynchronous
orbit Block DM missions last for 450 seconds and 230 seconds
respectively [7]. If it is assumed that the Block D and Block DM
engines have the same thrust levels, this would imply a propellant
load of 16.7 tonnes and 16.3 tonnes for the LOX/kerosene and
LOX/SYNTIN combinations respectively. In turn this would imply that
the propellant tanks would require an increase of 5%, but there is no
evidence of such a change from FSU scaled drawings (admittedly, such a
small change would be difficult to detect from the available
drawings). More realistically, the Block DM burn times probably
include the period that the engine is being throttled up to full
thrust, and thus will overstate the calculated propellant load.
Therefore, it is reasonable to assume that the maximum propellant
masses for the Block D and Block DM are the same - about 15 tonnes.
Such an assumption permits the performance which coincides with that
which has been demonstrated on Earth orbit and deep space missions.
The SOZ (stabilisation and launching provision) ullage motors use
nitrogen tetroxide and UDMH propellants [7]. Each assembly carries
five engines: two have a thrust of 5 kg provide pitch and yaw control,
one with a thrust of 10 kg provides yaw control and two with 2.5 kg
thrust produce longitudinal accelerations. The propellant mass is
about the same as the dry mass of each SOZ (56 kg) and when they
separate from the Block DM each SOZ still carries 10-40 kg of unused
propellant.
Block D and Block DM Launch Profiles
It will be realised from Table 1 that the Block D and Block DM
have different missions applications. Originally it was thought in
the West that the Block DM was introduced as a replacement for the
original Block D, but this is not the case. The Block D is used for
deep space missions to the Moon and planets (plus some Earth orbital
tests in the L-1 manned lunar programme), while the Block DM was
introduced for the geosynchronous orbit and GLONASS missions - all
dedicated Earth orbit missions.
The original Block D application as part of the L-3 manned lunar
programme required a multiple restart capability and this was used on
the standard Proton missions although from western analyses of the
Proton launch profile this was not realised. Based upon the launch
profile of the Molniya booster, it was thought that a third stage
placed the combined Block D/payload assembly in a low Earth orbit and
the Block D made a single burn out of Earth orbit.
In fact, this analysis is now known to be incorrect. From the
very first launches the first three stages of the Proton-4 were sub-
orbital and the Block D fired once to place itself and its payload
into a low parking orbit. The two ullage motors were then discarded
(to be tracked and wrongly identified as discarded rocket stages, etc
in western catalogues) and the Block D would re-ignite to place its
payload into it's planned trans-lunar or interplanetary trajectory.
On the other hand, when the Block DM was introduced the launch
profile became similar to that of the Molniya booster. because the
planned geosynchronous orbit payloads (and, later GLONASS payloads)
were far lighter than the lunar and planetary probes (typically they
were 25% or less than the deep space probes) which had been launched,
the three-stage Proton was able to place the third stage in orbit
with a fully-laden Block DM and satellite.
After reaching low Earth orbit the Block DM assembly and payload
separate from the Proton booster's third stage and 55 seconds later
the fourth stage casing is ejected. During a period of about 15
minutes a series of pre-programmed manoeuvres is completed by the
Block D/DM and some 40 minutes after launch the assembly is rotated by
180o to compensate for the gyroscopic shift of the guidance system:
this takes about 2.5 minutes.
Approximately 80 minutes after launch the fourth stage engine is
ignited as the assembly passes over the equator northbound. The
ullage motors on Block D missions separate as the burn begins: they
are small enough not to be tracked before orbital decay or when they
are tracked they remain in USSPACECOM's catalogue of temporary orbital
contacts and not normally transferred to the catalogues which the
public sees.
On Block DM missions to geosynchronous orbit the transfer orbit
inclination is shifted to 47.5o, close to the value required to
minimise the total manoeuvre value to geosynchronous orbit. A series
of rotations about the longitudinal axis of the rocket stage and
payload are made during the transfer orbit coast which even out the
effects of solar heating on the assembly: in the Apollo era this was
called "barbecue mode" during trans-lunar coasts. Generally three
axis stabilisation is maintained when not in this mode. During the
coast to the transfer orbit's apogee another 180o rotation is made to
align the guidance system gyroscopes - again taking 2.5 minutes.
After coasting half way around the transfer orbit preparations
are made for the second and final burn of the Block DM main engine
which takes place at the first transfer orbit descending node pass.
To settle the propellant remaining in the Block DM's tanks the two
ullage motors ignite 300 seconds before main engine ignition and are
ejected about 1 second after the main engine begins operating. These
are the two objects which have always been tracked in geosynchronous
transfer orbits and their purpose was previously unknown.
When the Block D and Block DM stages are shut down for the final
time subsequent operations are believed to be similar. Immediately
after shutdown a separation command is sent to the payload.
Approximately 15 seconds later the payload separates. During the
intervening period the assembly has been uncontrollable, with the
rotation about each axis possibly reaching a maximum of 5 o/sec. On
Block DM missions the rocket stage then vents its unused propellant.
Additional Comments on the Geosynchronous Mission Profile
The standard launch technique described above means that
geosynchronous orbit satellites will always be initially placed in
orbit over the same longitude. Given that the first burn of the
Block DM comes at the first equator crossing northbound which is over
10.3 oW, the longitude of the satellite at the time of geosynchronous
drift orbit injection will be:-
L = 169.56 - P/8
where L is the injection longitude (oE: 360o might have to be added to
the result to obtain a longitude in the range 0-360 oE) and P is the
transfer orbital period (minutes). Typically the transfer orbit
periods are 615-635 minutes, so this means that injection takes place
over 91.43+_ 1.25 oE.
This launch technique has resulted in some FSU data being
misunderstood in the West. In describing the launch technique for
geosynchronous missions the commercial FSU literature gave the final
orbital period as having a range of 1,436+_ 20 minutes, and this was
interpreted as the error range for the launch vehicle - apparently not
a particularly accurate launch vehicle ! Such an assumption was
immediately known to be incorrect by astute observers of the FSU space
programme.
Geosynchronous payloads generally enter drift orbits with periods
of 1,400-1,480 minutes and are then allowed to drift around the
geosynchronous band until they approach their planned longitude: they
then perform a small manoeuvre to reach a near-stationary 1,436 minute
orbit over the required longitude.
Therefore, the range of 1,436+_ 20 minutes was not an error range,
but the range of drift orbits which was being offered. In terms of
orbital injections the Block DM atop a Proton booster is at least as
accurate as any western launch vehicle system.
Other Block D and Block DM Mission Profiles
While the above description gives the typical mission profile for
a geosynchronous mission it has been varied for a few missions. A
disadvantage of the standard profile is that it limits the drift orbit
injection longitude. Commercial literature has noted that the Block
DM assembly can be maintained in the low Earth orbit for up to a day
before the first firing takes place. The previous formula for
orbital injection longitudes therefore requires amending to allow for
such a change in profile:-
L = 192.010 - 22.452*N - P/8
where N is the (integer) number passes through the parking orbit
ascending node before the first Block DM burn and with L and P as
before. The second burn of the Block DM always takes place at the
first pass through the transfer orbit descending node.
This modified launch technique was first used by Cosmos 1940 (the
first Prognoz early warning satellite), launched in April 1988.
After launch the Block DM/payload assembly remained in the low orbit
for four additional circuits and was then boosted to its transfer
orbit: this resulted in a drift orbit injection close to 0 oE. If
the Block DM had remained in the parking orbit for one additional
circuit the injection longitude would have been about 340 oE - closer
to the planned initial Cosmos 1940 location over 336 oE.
This technique has been used on two further missions - Cosmos
2155 (operated over 335 oE) and Cosmos 2209 (336 oE). However, it
has been used sparingly and other satellites heading towards
approximately the same area around the geosynchronous band have not
used the new profile and thus can take a couple of weeks to reach
their stations.
The GLONASS launch profile was originally similar to the
geosynchronous profile: the low parking orbit was at 51.6o but the
satellites were manoeuvred to 64.8o, 19,100 km orbits using two Block
DM manoeuvres (each involving a plane change): one manoeuvre would be
during the first parking orbit ascending node pass and the second
would be during the first transfer orbit descending node pass.
Starting with Cosmos 1710-1712 in 1985 the initial parking orbit
inclination was changed to 64.8o, meaning that no orbit plane changes
need be conducted. Since plane changes are no longer required the
initial Block DM manoeuvre can take place near the northern apex of
the parking orbit and the second one can come at the southern apex of
the transfer orbit.
The launch technique for Astron and Granat was a throw-back to
the original Block D profile, although the Block DM was apparently
used on the missions. For these two astronomical satellites the
first three stages of the Proton-4 booster were sub-orbital with the
combined Block DM/payload assembly being placed into a 200-2,000 km
initial orbit: apogee was in the southern hemisphere. The two ullage
motors were tracked in this orbit, but misidentified in western
catalogues as what we would now call the Proton third stage and Block
DM casing (in reality these had been sub-orbital). At the first pass
through apogee the Block DM re-ignited to place itself and the science
payload into an eccentric orbit reaching out to approximately 200,000
km.
A modification of the standard Block D launch profile was used
for the two Fobos launches in 1988. Contemporary Russian
descriptions of the launch and later written descriptions note that
the first three stages of the Proton booster were sub-orbital and the
Block D on each mission performed first part of the heliocentric
orbital injection phase.
On Fobos 1 a single low orbit object was tracked (1988-058C) and
on fobos 2 two were tracked (1988-059C and D): these would be the
discarded ullage motors, although one was not tracked for Fobos 1.
Heliocentric orbit injection was performed in two stages. The
second burn of the Block D placed the spacecraft into an orbit
reaching out to more than 130,000 km (as measured for Fobos 1), and
after the Block D was discarded the main propulsion system of the
Fobos spacecraft itself was used for the final injection to
heliocentric orbit.
The final unusual launch profile to be reviewed here is that for
Cosmos 1603 and Cosmos 1656. This profile is unique in that it marks
the only one which saw the Block DM ignited three times, and it is
discussed in detail elsewhere [8,9].
After launch the standard two objects were left in the initial
low orbit on these two missions. At the first pass through the
initial orbit's descending node the Block DM ignited for the first
time, placing the assembly in a 51.6o, 190-835 km orbit (this was the
first time that the Block DM had ignited on the initial orbit
descending node). At the first pass through the ascending node the
Block DM again ignited, raising the orbit to 815-855 km and changing
the orbital inclination to 66.6o. The ullage motors were cast off as
the third manoeuvre began, changing the orbit to 850 km circular at
71o. This final manoeuvre took place over Plesetsk, and therefore
was very expensive in terms of propellant (orbital inclination changes
should be done over the equator to minimise propellant consumption).
This launch profile has not been seen again after Cosmos 1656 in
1985, and later Zenit launches to 71o, 850 km orbits went directly to
the required orbital inclination - no plane changes were needed.
The Block D as Part of the Manned Lunar Programme
Having discussed the modern missions conducted by the Block DM
which have permitted insights for operations of the original Block D,
the manned lunar applications will be reviewed.
The Block D began its life as the fifth stage of the N-1/L-3
manned lunar landing complex: depending on how one wishes to
differentiate between a rocket stage and a spacecraft service module,
one could argue that the Block D was the L-3 lunar service module.
After launch of an N-1/L-3 vehicle the first two stages (Blocks A
and B) would have been sub-orbital, the third stage (Block V) would
remain in a low Earth parking orbit and the fourth stage (Block G)
would perform trans-lunar injection. After this the Block D and its
lunar payload separate from the Block G.
The Block D must have been capable of performing small trajectory
corrections during the trans-lunar coast, but its first major ignition
would place the assembly in a 110 km lunar orbit, later lowering it to
one with a periselene of 16 km [11]. Here the lunar Soyuz with its
Block I* propulsion system would separate when one of the two
cosmonauts flying the mission had transferred by EVA to the lunar
lander. The shroud covering the lunar lander would separate and the
Block D would ignite again to take the Block Ye lunar lander down
towards the Moon. The ullage motors on the Block D would separate at
the beginning of the lunar descent burn. At an altitude of 1.5-2 km
the dry Block D would separate and crash onto the lunar surface, while
the lunar lander would (hopefully !) soft land with its lone cosmonaut
some distance away.
With the information known about the individual components of the
L-3 lunar stack it is possible to derive realistic masses and
performance data for the lunar orbit and surface operations, and this
is summarised in Table 5. It is interesting to note that if the
Soviets had wanted to, they could probably have launched an Apollo 9
class mission using the Proton-4 booster carrying both the lunar
lander and the lunar Soyuz with cosmonauts (using the planned lunar
Block I propulsion system).
The flight profile of Cosmos 382 appears to have been unique, and
it is now known that the spacecraft was designated L-1E, and carried a
modified Zond spacecraft on a flight to qualify the Block D for
orbital manoeuvres over a period of some days - as would be required
on the L-3 lunar mission.
Although the flight of Cosmos 382 appears to have been unique,
there might have been two earlier missions which failed to reach
orbit. Western literature has noted that November 1969 saw the
unsuccessful launch attempt of a spacecraft with "quite similar"
telemetry characteristics to those of Cosmos 382 [14], so this might
have been the first L-1E launch. Official FSU literature released as
part of the Proton booster commercialisation indicates a launch
failure of a four stage Proton in February 1970, the payload being
identified as a Cosmos satellite: the only Cosmos to be launched atop
a Proton close to this time which was not using the name simply to
cover a launch vehicle or payload malfunction was Cosmos 382:
therefore the February 1970 failure might also have been a L-1E launch
attempt.
The other flights of the Block D within the manned lunar
programme were as part of the Zond/L-1 launch vehicle. In 1967
Cosmos 146 was a successful Zond/L-1 test with the Block D reportedly
performing two manoeuvres, while Cosmos 154 on a similar mission was
unsuccessful when a control system failure resulted in one of the two
ullage motors separating early, thus preventing Block D ignition.
These two spacecraft were designated L-1P, as precursors to L-1
missions proper.
During 1967-1970 four unsuccessful and five successful launches
of Zond spacecraft were completed using the Proton-4/Block D
combination: of the successful launches, Zond 4 apparently travelled
to a lunar distance but was launched away from the Moon, while Zonds
5-8 performed loops around the Moon [15,16].
The Future of the Block D/DM Propulsion System
FSU engineers have announced plans for future uses of the Block
D/DM technology, although it is presently unclear how many of the
plans will be brought to fully operational systems.
When the first FSU literature appeared describing the planned
upper stages of the Energiya shuttle booster [17] it was immediately
realised by western analysts that what was being described as the
retro- and correction stage (R&CS) was simply the Block D under
another name. Drawings of the R&CS do not show the control unit of
the Block DM being carried, although this could simply be an omission
by the artist.
The R&CS is proposed for three classes of mission. One is
simply to provide the propulsion necessary to place a 90 tonnes
payload into a relatively low Earth orbit. The second is an
application as an inter-orbit space tug. And the third is to act as
a spacecraft service module for either lunar landing or Mars
orbiter/landing missions.
A pair of Block D engines appears to be used as the orbital
manoeuvring system of the Buran space shuttle, which might still go
down in history as the first reusable space shuttle which only had a
single orbital flight.
Finally, the Block DM has been proposed for addition to the two
stage Zenit (Zenit-2) booster to give the Zenit-3, capable of
geosynchronous orbit missions. In terms of useful payload, the
Zenit-3 only seems to make sense if it is to be flown from an
equatorial launch site, from where it can match the current Proton
capability from Tyuratam to geosynchronous orbit. Zenit-3 was
supposed to fly from the proposed Australian Cape York launch site,
but that project has been in a state of flux for a few years and its
future (as well as that of the Zenit-3) is extremely uncertain.
The Block D and Block DM Flight Record
Table 6 presents what can be considered to be a complete list of
the failures which involved the Block D and Block DM. Such failures
are easy to detect since they normally take place after parking orbit
injection, and thus the debris from the launch (operational or
otherwise) is catalogued in the public domain.
Failures which are more difficult to track down are those which
failed to reach Earth orbit, and there are two known cases of the
Block D preventing orbital injection (Luna probes in 1969 and 1975).
The May 1993 Launch Failure
A Proton-4 was launched on May 27 1993 but failed to place a
Gorizont communications satellite in orbit. While the ITAR-TASS
launch announcement appeared garbled, something closer to the correct
story was obtained by Nicholas L Johnson in conversations with Boris
Cherniatiev [19]. The second stage of the launch vehicle failed to
perform nominally, but the third stage operated as planned, although
it was incapable of generating the velocity required to reach orbit.
As a safety measure the Block DM vented all of its propellant and
subsequently was destroyed when it burned up in the atmosphere.
The venting of the propellant from the Block DM is a procedure
which had previously been unknown from FSU literature.
The cause of the failure was later said to have been due to too
high a level of copper in the propellants.
NPO Energiya (USA) Data For the Block DM Variants
A leaflet issued by the Energiya USA company [20] describing the
Block DM includes numerical data which differs from that quoted
elsewhere in this review. As is often the case when data from
different Russian sources disagree it is not possible to be definitive
in saying which is correct and which is in error.
The leaflet describes two versions of the Block DM: one with an
equipment bay and one without. Other literature has indicated that
the fourth stage with the bay is the Block DM and that the one without
the bay is the older Block D. However, it is possible that the
Energiya USA literature is describing an as-yet unflown variant of the
Block DM without the equipment bay.
The Energiya USA leaflet notes that the Block DM propulsion
system permits operations over a period of up to 240 hours - more than
long enough for all of the Proton-4/Block DM missions described in
Russian literature.
Table 7 provides the mass details for the Block DM variants noted
in the Energiya USA literature.
The Block DM engine is described as being developed by NPO
Energiya during 1970-1973, the first flight coming in 1974. The
Block DM fuel characteristics are quoted in Table 8, again based upon
the Energiya USA leaflet. It is also noted that the Block DM can be
fired up to seven times, although if necessary this number can be
increased. There is a nozzle expansion ratio of 3,000 due to the use
of a "radiation-cooled" nozzle extension made of columbium alloy.
Finally, the Energiya USA literature has included details of the
performance of the LOX/Kerosene and LOX/SYNTIN versions of the Block
DM, possibly called the DM-1 and DM-2 respectively (Table 9). Once
more, Russian literature has used these designators inconsistently.
In 1994 all of the Proton missions have been credited as using the
Block DM-2 variant.
The engine reliability is claimed to be 0.997, with a proven
success probability of 0.9.
References
[1] V P Glushko (editor), Cosmomavtika Entsiklopediya (published
1985 in Russian), p 48.
[2] V P Glushko, Razvitiye Raketostroeniya i Cosmonavtiki i SSSR
(second edition, published 1981 in Russian), pp 194-198.
[3] V P Glushko (editor), Cosmomavtika Entsiklopediya, p 498.
[4] V P Glushko, Razvitiye Raketostroeniya i Cosmonavtiki i SSSR
(third edition, published 1987 in Russian), pp 252-254.
[5] Phillip S Clark, "Soviet Spacecraft Masses for Earth Orbital
Programmes", Journal of the British Interplanetary Society, January
1985, pp 19-24.
[6] Phillip S Clark, "Soviet Spacecraft Masses for Deep Space
Missions", Journal of the British Interplanetary Society, January
1985, pp 25-30.
[7] B V Cherniatiev et al, "Identification and Resolution of an
Orbital Debris Problem with the Proton Launch Vehicle", presented at
the ESA First European Conference on Space Debris, Darmstadt (5-7
April 1993) and SPIE Space Debris Detection and Mitigation Conference,
Orlando (15-16 April 1993).
[8] Phillip S Clark, unpublished correspondence, 6 November 1984.
[9] Phillip S Clark, "Obscure Unmanned Soviet Satellite Missions",
submitted for publication in Journal of the British Interplanetary
Society (paper presented at the BIS Soviet Astronautics meeting, 12
June 1993). Section 9 of the paper refers to Cosmos 1603 and Cosmos
1656.
[10] V P Mishin, Pochemu Mou Ne Sletali Na Lunu ?, Znanye issue 12
1990, p 20.
[11] I B Afanase'ev, Neizvestnaye Korabli (Unknown Spacecraft),
Znanye issue 12 1991, p 29.
[12] Phillip S Clark, "Obscure Unmanned Soviet Satellite Missions",
ibid: section 7 discusses the lunar stack and Cosmos 382.
[13] V Filin, "Project N1-L3", Aviatshiya i Cosmonavtika, issue 2
1992, p 40.
[14] Anon, "Salyut Elements Separate, Signals Lost", Aviation Week &
Space Technology, 30 April 1973, p 21.
[15] I B Afanase'ev, ibid, pp 24-27.
[16] Phillip S Clark, "The Soviet Manned Circumlunar Program",
Quest, Winter 1992, pp 17-20 (reviews the material in reference 14).
[17] B I Gubanov, The Space Vehicle for Today and Tomorrow, Space
Studies Institute paper SSI BIG-2 (1990), figure 3.
[18] G Y Maksimov, From the History of Constructing and Testing of
the First Soviet Automatic Interplanetary Stations, paper presented at
the 1991 IAF Congress (IAA-91-690).
[19] Nicholas L Johnson, private conversations, 28th May 1993.
[20] Anon, Multipurpose Cryogenic Block DM with 11D58M Engine, paper
issued by Energiya USA during 1993.
Illustration Captions
Figure 1 The original Block D stage without its outer casing. The
spherical tank at the top carries the liquid oxygen oxidiser and the
lower torus tank carries the kerosene fuel. As with Figures 2, 3 and
4, the dimensions are given in mm on the original FSU material. This
stage as flown on the four stage Proton booster is possibly little
changed from the original fifth stage to be carried on the N-1 lunar
booster. (Copyright NPO Energiya and Kaman Sciences Company)
Figure 2 The Block DM, shown both inside its casing and without the
casing. The identically-sized case is believed to be used for the
Block D. It will be noted that the only real difference between the
Block D and Block DM is the presence of the control unit added above
the oxidiser tank. (Copyright NPO Energiya and Kaman Sciences
Company)
Figure 3 One of the two small ullage motors which are carried by the
Block D and Block DM stages. On Block D missions they are not
normally tracked in orbit, but the resulting orbit would be so low
that the motors could decay before being catalogued. On Block DM
missions the motors separate one second after the final ignition of
the main engine. (Copyright NPO Energiya and Kaman Sciences Company)
Figure 4 Russian drawing of the L-3 lunar stack carried aboard the
N-1 booster [10]. This Russian drawing is used rather than a western
re-drawn version since the majority of re-drawn versions include
details of what the western artists think should be shown rather than
what the Russian drawing actually does show. (Originally published
in Znanye, issue 12 1990)
Figure 5 The retro- and correction stage proposed for the Energiya
booster. This appears to be a virtually unmodified Block D, the
major change being an improved and longer-life refrigeration system
being carried. The two ullage motors are identified as "auxiliary
propulsion" in this Russian drawing. (Copyright NPO Energiya)
Table 1 Summary Launch Record of Proton Block D and Block DM Missions (to the end of June 1994)
Spacecraft Series Period Proton-4/Block D Proton-4/Block DM
Failures Block D Block D Failures Block DM Block DM
to LEO Failures Successes to LEO Failures Successes
Astron 1983 1
Cosmos (GEO/comms) 1974-Date 1 12
Cosmos (GEO/ELINT/EW) 1975-1986 4
Cosmos (GEO/EW) 1988-Date 4
Cosmos (GLONASS) 1982-Date 2 20
Cosmos/Zond (L-1P/L-1) 1967-1970 4 1 6
Cosmos (L-1E) 1969-1970 2? 1
Cosmos 1603/1656 1984-1985 2
Ekran 1976-Date 4 20
Fobos 1988 2
Gals 1994-Date 1
Gorizont 1978-Date 1 1 29
Granat 1989 1
Luna 1969-1976 2? 4 10
Mars 1969-1973 2 1 6
Molniya-1S (GEO) 1974 1
Raduga 1975-Date 1 31
Raduga-1 1989-Date 3
Unknown (GEO) 1988+1990 2
Venera/VEGA 1975-1984 10
Totals 10? 6 35 8 4 129
Notes Launches are noted in the alphabetical order of satellite names. For each programme the
launches are summarised as failures to reach orbit, Block D/DM failures once in orbit and launch
successes. Launch failures to reach orbit are based upon FSU literature together with some western
rumours: the failures of two Luna probes (February and April 1969) and one possible Cosmos (L-1E)) to
reach orbit in 1969 have not been confirmed in FSU literature. In addition, the FSU launch records of
the Proton booster indicate launches of geosynchronous orbit payloads in 1988 and 1990 which failed to
reach orbit: the intended payload names for these missions are unknown. Cosmos missions have their
programmes indicated: GEO - geosynchronous orbit, comms - communications, EW - early warning.
Table 2 Basic Data for the Block D
Length 5.5 metres
Diameter 4 metres
Total mass 17.3 tonnes
Engine thrust 85 kN
Engine specific impulse 350 sec
Burn time 600 sec
Notes These data are extracted from reference 3, page 48 (the "Block
D" entry).
Table 3 Dry Masses for Various Block Ds (derived from FSU Literature)
Mission(s) Dry Mass Mission(s) Dry Mass
kg kg
Cosmos 146 1,800 Luna 15 1,785
Luna 16-17 1,888 Luna 18-19 1,937
Luna 20 2,160 Luna 21 1,843
Luna 22-23 1,826 Luna 24 1,830
Mars 2-7 1,714 Venera 9-10 2,018
Venera 11-12 2,020 Venera 13-14 1,925
Venera 15-16 1,925 VEGA 1-2 1,920
Zond 4-6 1,792 Zond 7-8 1,796
Notes These figures are derived from references 2, 3 and 4 with the
derivation of pre-1981 masses discussed in reference 6. For the 32
Block Ds listed above the mean mass is 1,862 kg with a standard
deviation of 111 kg. However, it is reasonable to split the data
into three groups. The first represents the Block D missions through
to the end of 1970, and are thus stages close to the original N-1
variants: the mean mass and standard deviation comes to 1,814 kg +_ 40
kg. The second are the Mars 2-7 Block Ds which had unusually low
mean masses of 1,714 kg. Finally, the remainder of the Block Ds
flown during 1971-1984 have a mean and standard deviation of 1,940 +_
85 kg.
Table 4 Actual and Derived Block D and Block DM Data
Item Block D Assembly Block DM Assembly
Length Diameter Dry Propellant Total Length Diameter Dry Propellant Total
Mass Mass Mass Mass Mass Mass
m m kg kg kg m m kg kg kg
Stage Casing 3.996 3.700 800 -- 800 3.996 3.700 800 -- 800
Stage 5.366 3.700* 1,860 14,800 16,660 6.218 3.700* 2,350 14,800 17,150
Ullage Motor 1.000 0.600 56 60 240** 1.000 0.600 56 60 240**
Notes The derivation of the above figures is discussed in the text. The rocket stage diameters marked
* refer to the maximum values, while the total mass for the ullage rockets marked ** refers to the two
motors together which are carried by each rocket stage. The Block D dry mass which is quoted is the
overall mean for all the stages noted in Table 3.The lengths and diameters are quoted above to the same
(apparent) accuracy as the FSU literature permits.
Table 5 Mass Model of the L-3 Lunar Stack
Spacecraft/Component Total Propellant Delta-V Comment
Mass Mass
Block I/Soyuz 9,400 kg 400 kg 120 m/s LO manoeuvres: isp = 280 sec
2,700 kg 1,100 m/s TEI manoeuvre: isp = 315 sec [?]
Block Ye/Lunar Lander 5,500 kg 100 m/s Cushion landing: isp = 315 sec [?]
1,900 m/s Lunar ascent: isp = 315 sec [?]
Lunar Lander shroud 1,000 kg Surrounds lunar lander until Soyuz
separates
Block D 16,580 kg 14,780 kg 1,000 m/s LOI manoeuvre: isp = 352 sec
2,100 m/s Lunar descent: isp = 352 sec
Ullage Motors 240 kg 120 kg Two motors, cast off as lunar
descent begins
Block D casing 800 kg
Total L-3 Stack 33,520 kg
Notes The masses of most of the above components are from Soviet literature or derived from material
given in Soviet literature: the only exception is the lunar lander shroud. The dry mass of the Block D
is taken to be 1,800 kg, close to the mean value derived for the 1967-1970 period (see Table 3). The
lunar lander comprises two sections: the landing frame, mass 575 kg (?), and the ascent stage, mass 4,925
kg (?). Abbreviations used above are: LO - lunar orbit, TEI - trans-Earth injection, LOI - lunar orbit
injection. The magnitudes of the manoeuvres are based upon requirements from Apollo 11 and taken from
the Apollo 11 Press Kit. Estimated specific impulses (Isp) are noted by "[?]", and are based upon
typical specific impulse levels of engines being developed by the Isayev bureau during the mid-late 1960s
(although the Block Ye was actually the product of the Yangel bureau).
Table 6 Summary of Block D and Block DM Failures
Launch Date Payload Block Comment
1967 Apr 8 Cosmos 154 D Zond/L-1P test. Control failure resulted in one of the
ullage motors separating early, thus preventing Block D
ignition.
1969 Jun 14 -- D Luna probe. First Block D burn intended to place the
rocket stage and spacecraft in low Earth orbit failed.
1969 Sep 23 Cosmos 300 D Luna probe. Cause of failure not known. Only two
objects catalogued from launch, possibly indicating
that not even the Block D casing separated.
1969 Oct 22 Cosmos 305 D Luna probe. As Cosmos 300. Launch announcement
gave no orbital period, suggesting that less than one
orbit was completed: Block D mis-aligned at ignition,
thus driving the Luna probe back into the atmosphere
instead of out towards the Moon ?
1971 May 10 Cosmos 419 D Mars probe. On-board flight sequencer mis-programmed,
preventing even separation from Proton third stage after
reaching parking orbit.
1975 Oct 16 -- D Luna probe. First Block D burn intended to place the
rocket stage and spacecraft in low Earth orbit failed.
1978 Dec 19 Gorizont 1 DM Communications. Borderline case of failure. Block DM
mis-aligned for second manoeuvre, leaving satellite in
11.3o, 22,580-48,365 km orbit instead of approximately
1.5o, 36,000 km circular.
1987 Jan 30 Cosmos 1817 DM Communications (could have been an intended Raduga,
Ekran or Gorizont satellite). Block DM failed to
ignite following casing separation. Glavcosmos stated
that this Block DM had some experimental modifications
which caused the failure.
Table 7, cont
Launch Date Payload Block Comment
1987 Apr 24 Cosmos 1838-1840 DM GLONASS (navigation). Block DM shut down early during
first manoeuvre, attaining a 64.8o, 190-17,500 km orbit,
apogee some 2,000 km lower than intended. Glavcosmos
stated that same modification as on Cosmos 1817 caused
the failure.
1988 Feb 17 Cosmos 1917-1919 DM GLONASS (navigation). Unspecified failure prevented
separation of Proton third stage and Block DM. Flight
sequencer deployed satellites in low parking orbit.
Table 7 Block DM Variants Described by Energiya USA Leaflet
With Equipment Without Equipment
Bay Bay
Mass of Block DM, completely integrated
and loaded with propellants 18,400 kg 17,650 kg
Propellant load: 15,050 kg 15,050 kg
oxidiser 10,600 kg 10,600 kg
fuel 4,300 kg 4,300 kg
Mass of dry Block DM, fully intergrated 3,350 kg 2,600 kg
Dry Block DM at staging 2,500 kg approx 1,700 kg approx
Notes TYhese numbers are taken exactkly from the tablwe on page 3 of [20]. It should be noted that
the propellant masses as quoted do not agree: in each case the sum of the constituent oxidiser and fuel
is 150 kg less than the propellant load. It is possible that this is because the latter figures include
the ullage motor propellants while the former do not.
Table 8 Block DM Fuel Characteristics
Fuel Density at Viscosity, centistoke
at 20 oC at 20 oC at -40 oC
Kerosene (RP-1 type) 833 kg/m3 >2.5 <25
SYNTIN 851 kg/m3 1.437 5.44
Notes This is reproduced from the table on page 5 of [20].
Table 9 Comparison of the Block DM Engine Data for Kerosene and SYNTIN Applications
Fuel Kerosene SYNTIN
Thrust, kgf 8,500 8,800
Thrust, kN 85* 88*
Thrust,tonnes 8.7* 9.0*
Chamber pressure, kg/cm2 79 81
Exhaust velocity, m/s 3,452* 3,540*
Specific Impulse, sec 352 361
Notes Reference 20 gives the thrust values in kgf: the values marked * are converted from these values.
Similarly, the document quotes the specific impulses and again the exhaust velocities are simply
conversions of these.