Energia-M
Contents
Development history
Studies on smaller Energia variants or derivatives began even before the Buran programme was officially given the go ahead by the February 1976 decree by the Communist Party’s Central Committee.
The lineage can be traced back to Glushko’s first proposals for the RLA family. By October 1974, the RLA line-up had evolved to form part of NPO Energia’s Integrated Rocket and Space Program. The line-up consisted of four vehicles: the massive lunar-capable RLA-150, the RLA-130 and RLA-140 shuttle launchers, and the smallest, the RLA-120.
Prologue: RLA-120 and the arrival of the Zenit
Glushko’s original RLA concept developed back at Energomash was built on clustering 6 meter diameter common propulsion blocks running on tsyklin or kerosene, but despite his strong dislike of hydrogen as fuel, it had slowly made its way into the design — first on the upper stages, then by October 1974 it became the fuel for the MTKS shuttle’s main engine, the RD-135.
Nevertheless, commonality of hardware remained a significant feature of the project and that commonality began with the RLA-120, a 6 meter diameter single-stick (or monoblock in Russian parlance) vehicle capable of launching 28–30 tonnes to a 51.8° by 200km reference orbit. Its first stage was fueled with liquid oxygen and kerosene, powered by a 1000 tonne thrust RD-150 engine aided by RD-124B verniers and became the common booster of the entire range of vehicles; the RLA-130 shuttle launcher used two RLA-120 first stages either side of a hydrolox core, the RLA-140 added reusability for the boosters and the massive RLA-150 used a cluster of six boosters around the hydrolox core stage.
Meanwhile, NPO Yuzhnoe had been developing their own medium lift vehicle designated 11K77, which in 1975 moved from hypergolic propellants to kerosene and liquid oxygen. Yuzhnoe turned to Energomash for new first stage engines — the 600 tonne RD-123. The launcher was also (by that point) a single-stick design, with a consistent 3.9 meter stage diameter — the largest that could be transported across the USSR by rail. Later in 1975, the RLA family absorbed the 11K77 and adopted its first stage as the common booster in place of the old RLA-120 first stage.
The smallest RLA launcher retained the RLA-120 name, but this time was built around a ~4 meter hydrolox core stage with two 11K77 boosters and could deliver 33 tonnes to a 50.7° by 200km reference orbit with expendable boosters and 30 tonnes with booster reuse. The standalone 11K77 launcher later received a familiar name — Zenit. The design was carried over with only minor changes to the flightworthy configuration of Energia and succesfully flew on its own as the two-stage Zenit-2 and three-stage Zenit-3.
With smaller and less powerful boosters, the RLA-130 now needed four strap-ons instead of two; when the main engines moved from the orbiter to the core stage in 1976, the rocket started to resemble the Energia we now recognize from photos.
RLA-125
Between 1975 and 1977, a new 30–60 tonne payload vehicle was studied in parallel with 11K77 and RLA-130.
The initial configuration of such vehicle was the RLA-125, described in a 1976 technical proposal. The vehicle could lift 45–50 tonnes to LEO and was based on the cargo version of Energia, Buran-T; but it had two strap-on boosters instead of four. The core stage (still at the pre-1978 8.37 m diameter), together with its four RD-0120 engines was carried over and would hold 790 tonnes of propellant. The side-mounted payload container was also retained.
In 1977, the designers of the Energia explored a four-tank version of the core stage with the diameter reduced to 7.75 m and only three RD-0120 engines, albeit uprated from 190 to 250 tonnes of thrust. The stage was divided into two sections, each with its own oxygen and hydrogen tank; the engines would consume propellant from the lower section, while the tanks were being refilled from the top section. Once the top section was empty, it would be jettisoned with the help of small rocket motors, reducing the dry mass of the stack and improving performance. The Energia returned to the standard two tank configuration the following year, retaining the new 7.75 meter diameter, but the four tank design made its way into the next version of the two-booster Energia derivative.
The 1978 proposal showed a shortened core stage (essentially the lower section of the four-tank core) with the payload positioned inline with the core instead of side-mounted. The short core stage together with the payload fairing had the same contour as the four-tank Energia core. The propellant mass in the core stage was reduced from Energia’s 700 tonnes to 460 tonnes and the number of RD-0120 engines was carried over from the four-tank Energia at three. Depending on the upper stage configuration and mission requirements, the two RD-170-powered Blok A boosters could fly without the recovery bays to improve performance. In the four tank version of Energia the boosters were given small fins at the top and bottom of the cylindrical section; it is unknown if this design feature was also present on this concept.
Very little information is known about the proposed cryogenic upper stage, Blok B, other than that it would have used the 11D57M engine, a variant of the RD-57 originally designed for the N-1M’s Blok S with a specific impulse of 460 s and 42 tonnes of thrust. The launch mass of this vehicle was 1260–1280 tonnes and it could lift 45–59.5 tonnes to LEO, 5.5–6 tonnes to GEO, 14.5–15 tonnes to TLI and 12–12.5 tonnes to TVI.
1978 saw the creation of a number of Energia derivatives, this time not limited to two boosters. The RLA-131 used the short core stage with an inline payload fairing and 4 Blok A boosters, the RLA-132 and RLA-133 used the same recipe but with 8 boosters, with Blok A boosters of the latter stretched to accommodate 50% more propellant. Two side-mount versions were also created: GTK-4 and GTK-6 with 4 and 6 Blok A boosters, respectively — these seem to have been designed around the full four tank core according to Hendrickx.
After the Energia core stage design returned to the two tank configuration in 1978 and the design of the vehicle was frozen in 1979, work on derivatives and variants was suspended and all focus shifted to making Energia fly.
Groza and inelegant design
It wasn’t until 1984 that work on new launchers resumed with a government resolution on the development of new launch systems; this time the payload requirements were amended to 30–40 tonnes to LEO with a goal of GEO payload capability surpassing that of the modernized Proton (presumably referring to the introduction of the Blok DM-2 upper stage on Proton in 1982). The deadline for the release of preliminary designs was set to 1985, with a decision on funding to follow a year later. Three research directions were specified: 11K37, upgraded Proton, and Groza — as the modified RLA-125 was named.
It’s worth noting that “Groza” generally refers to a two-booster Energia derivative, where the payload is side-mounted, while RLA-125 encompasses all designs in this series of heavy-lift two-booster vehicle designs.
In December 1985 the preliminary design for Groza was released. The vehicle was just the cargo configuration of Energia without two of the four boosters; the core stage, pad infrastructure and the boosters themselves were all carried over from Energia. A new payload container, developed from Energia’s standard GTK was the only major new piece of hardware. The core stage carried 703 tonnes of propellant and Groza could lift 60–63 tonnes to LEO, depending on the source.
Retaining the standard Blok A boosters presented some problems when the rocket was on the pad, however, as wind speeds that were acceptable for a standard Energia stack generated critical loads when the vehicle could only be supported by two of the four boosters. To solve this, an extra set of booster supports was added to the Blok Ya launch table adapter and the wind speed limit for launch was lowered. This minor change let Groza retain complete hardware commonality with standard Energia and reduce the workload on the factories preoccupied with getting Energia production going at full steam, although the lopsided design was criticised as “inelegant”.
217GK “Neutron”
In July 1987 an expert commission on the RLA-125 and 11K37 projects was formed and in August the following year the Ministry of General Machine-building (MOM) amended the requirements to a more reasonable 25–40 tonnes to LEO for “science, national economy [and] defense” missions. With this change, the number of engines on the core stage would be reduced to one or two and the core itself would need to be smaller and the payload would move to the top of the stage.
At least two reduced-diameter options were considered, 4.1 meters (reminiscent of the 1975 RLA-120 core stage) and 5.5 meters. The propellant load would range from 200 to 450 tonnes depending on the diameter. Despite the smaller core stage and fewer engines, the proposed variants would allow a payload capacity of 27 to 50 tonnes to LEO. The preferred option was the 5.5 meter core with a single RD-0120, which would yield a 35 tonne payload capacity to LEO and 6.3 tonnes to GEO, and could be expanded into a new series of 5.5 meter launchers.
This would, however, require retooling the Progress plant in Kuybyshev, so by 1989 a version of Groza with a shortened Energia core stage at 7.7 meter diameter with one centrally mounted RD-0120 was chosen instead. The payload fairing was a shortened version of the GTK payload container for Energia and retained its 6.7 meter diameter. In July 1990 the concept was approved by the Council of General Designers at NPO Energia and given the name Neutron.
Moving towards launch?
Shortly after the design was approved in 1990, Neutron was renamed to Energia-M at the suggestion of NPO Energia Chief Designer Yuri Semenov, citing high hardware commonality with the Energia vehicle. That same year, a team was formed to create full scale model of the Energia-M and later in 1990 the mockup was built and tested in Baikonur at the Universal Test Stand and Launch Complex (UKSS) — the site of Energia full stack static fires and the launch site for Energia’s first flight carrying Polyus — and one of the two pads at Site 110, the former N-1 launch complex now adapted to Energia launches.
Only later, in April 1991 a government resolution directed NPO Energia, NPO Yuzhnoye and KB Salyut to submit proposals for new 25–40 tonne payload launchers, essentially a repeat of the 1984 tender but amended to the new payload requirement. In July 1991 Energia-M was selected as the winner and approved for development; over the next two years the design documentation was created and the manufacturing base was prepared.
In 1993 the technical specification for Energia-M was released, with a 34 tonne to LEO payload capacity and a launch mass of 1054 tonne, the rocket was slated for a 1995 debut launch. In 1992, however, the post-Soviet drive to develop a home-grown next generation family of launch vehicles and a realisation that Energia-M was oversized for most payloads caused the focus to shift on the Angara project to replace the aging Proton.
The May 1993 Energia Council of Chief Designers document which included the decision to stop work on the Energia-Buran program due to a lack of funds recommended the acceleration of work on Energia-M instead and requested funding. It then suggested using existing Energia hardware to develop Energia-M. The hardware used would be as follows:
- Blok A boosters from Energia serial 4L, 5L and 6L
- Blok A boosters from Energia 5S and its Blok Ya adapter
- set of RD-0120 engines from the Energia 4L core stage
- set of 17D75 solid propellant separation engines from Energia 4L
- gimbal steering drive systems from the Energia 4L core stage
- instrumentation and cable network of the autonomous control complex (only for the engineering mockup Energia-M N-14 serial 5T)
- valves for pneumatic hydraulic systems of core stages and Blok Ya adapters and “other components”
Using Energia hardware, Energia-M test article 5T could be built, and would test the N-14 upper stage configuration — Blok-DM with jettisonable auxiliary fuel tanks. Under the 5T1 designation, the same test article would be used to test the N-11V and N-11Ya two-stage configurations; it is unclear what the difference between them was.
The following test and flight schedule was described:
- static fire test of the 5S test article in the N-11V configuration, Q4 1994
- launch of the Mir-2 base block mockup on Energia-M serial 1L, Q4 1995
- launch of the Yamal satellite mockup on Energia-M serial 2L, Q1 1996
- launch of the Mir-2 base block on Energia-M serial 3L, Q2 1996
- launch of the Yamal satellite on Energia-M serial 4L, Q1 1997
- launch of the Safir (“Sapphire”) spacecraft mockup on Energia-M serial 5L, Q3 1997
After 1993 the development of Energia-M slowed sharply and in 1995 the funding was suspended. The project was over.
Epilogue
As NPO Energia was finding it ever harder to come up with the funding and support for Energia-M, they started coming up with some interesting use cases and payloads. Around 1991–1993, the company explored launching the 35 tonne OK-M2 reusable spaceplane on the rocket and equipping the launcher with winged flyback boosters.
The Energia’s Blok A boosters were designed with reuse in mind, with the RD-170 engines rated for 10 missions; the boosters would land under parachute. For Energia-M the boosters would be winged and would gently glide back to a runway after separating from the stack. The booster would mass 68 tonnes at landing, 17 tonnes of which would be the wings, landing gear and other recovery hardware, and would be able to land up to 320 km away from where the rocket was launched.
NPO Energia had been studying smaller spaceplanes as replacements for the Soyuz and Progress in space station operations since 1984. They usually received a designator beginning with OK-M; OK-M2 was a version developed with NPO Molniya, the organisation tasked with creating the Buran airframe. OK-M2’s shape resembled that of Molniya’s MAKS spaceplane, massed 30 tonnes and would be able to launch 10 tonnes to a 51.6° by 250km reference orbit.
The spaceplane had folding wings and used a combination of fuel cells and batteries for electrical power. It was connected to the launch vehicle with an adapter identical to the one designed for launches on Zenit and included solid fuel abort motors. Three ethanol/oxygen engines and 27 thrusters made up the OMS system. OK-M2 could carry four crew in the crew compartment and another four in an additional crew module in the 40 m³ payload bay.
Another interesting concept was the idea of launching the Energia-M from a platform on the Atlantic Ocean, which entirely avoided the complicated question of Russia’s relationship with Kazakhstan after the collapse of the USSR and the status of the Baikonur cosmodrome. One of the proposed missions would use the launcher to deposit nuclear or toxic waste into a graveyard orbit or send it on an Earth escape trajectory. That hasn’t been a popular one of course, but the idea of launching rockets from a platform in the sea on the equator later evolved into the Sea Launch project.
Being the USSR’s prospective Proton replacement, Energia-M was included in some space station planning documents in the 80s and early 90s. This Mir-2 planning document from around 1990 shows the use of Energia-M (Neutron) to lift modules for the next generation space station.
Energia-M technical description
This section is based on the description in Gubanov, 1999.
The Energia-M is a two stage vehicle with an optional third stage depending on the mission requirements. The core stage, Blok V, is a derivative of the Energia core stage Blok Ts, shortened and adapted for attaching in-line payloads which are contained in a two-part fairing. The vehicle’s boosters, Blok A, carried over from the Energia, are attached to the core stage at the bottom and the payload fairing at the top. A standard Blok Ya launch table adapter is used to assemble the vehicle, carry it to the pad on the “Grasshopper” transporter-erector (TUA) and erect it on the pad. During launch, Blok Ya remains on the pad, providing hydraulic, pneumatic and electrical connections between the pad infrastructure and the core stage right until lift-off.
Launch vehicle configurations and upper stages
One of the features Energia-M inherited from the standard Energia was that the payload or upper stage separated from the core stage while the stack was still on a marginally suborbital trajectory; this ensured that the core stage re-entered in a controlled area in the Pacific. As a result, in the two stage version of Energia-M the payload had to provide its own propulsion to perform the final insertion and circularisation burn. The “raw” payload capacity of Energia-M, that is the payload capacity at separation from the core stage was 35 tonnes at 50.2° inclination and 27 tonnes at 97°. The payload capacity to “usable” circular orbits was a bit lower at 34 tonnes to a 200km, 50.2° inclination Low Earth Orbit and 24.5 tonnes to a 500 km, 97° inclination Sun-Synchronous Orbit. The two stage version was known as the N-11 configuration; three more configurations with upper stages were proposed, which received the designations N-12, N-14 and N-15.
N-12 used a modified Blok-DM stage with a 11D58MF engine for up to 3 tonnes to GEO. There were plans to fly this stage on Zenit, Proton and the first version of the Angara.
N-14 was identical to the 204GK configuration planned for Buran-T; a Blok-DM with a standard 11D58M engine and jettisonable auxiliary fuel tanks. This version would increase the payload capacity into GEO to 5.5 tonnes.
N-15 was a LOX-LH2 upper stage on which information is quite limited, but it could carry 6.5 tonnes to GEO and had very respectable capacity to Lunar, Venus and Mars transfer orbits.
Blok V core stage
The core stage of the Energia-M shares the diameter of Energia’s Blok Ts at 7.75 m. The total height of the stage is 25.5 m with a 20–25 tonne dry mass. Five major components make up the Blok V structure: the engine section, fuel (LH2) tank, intertank compartment, oxidizer (LOX) tank, and interstage, to which the payload fairing and payload interface ring are attached. The core stage was designed to maximise the reuse of existing Energia manufacturing facilities and tooling, which resulted in a somewhat “inelegant” shape of the vehicle, but kept the development costs down. Pneumatic and hydraulic systems also use many elements borrowed from Energia’s Blok Ts, but the interfaces and systems themselves are simplified and use fewer components.
The hydrogen tank shares the 4.185 m radius spherical domes with Blok Ts’ hydrogen tank, although they have fewer flanges and the LOX feed line is a smaller diameter compared to Blok Ts. The domes are joined by an 8 meter long cylindrical shell made from four panels, similar in construction to Blok Ts’ oxygen tank, but smooth instead of milled into a waffle-like “orthogrid” pattern. The interior of the tank houses similar equipment to the Blok Ts hydrogen tank with anti-slosh baffles and a helium pressurisation system, although the number of the helium cylinders and valves is reduced. The hydrogen tank capacity is 600 m³ (compared to 1400 m³ in Blok Ts) with a height of around 15 m.
The oxidizer tank of Blok V uses a cylindrical section half the length of its Blok Ts counterpart (one ring section instead of two) and both domes are spherical, again with a 4.185 m radius (the top “dome” on Blok Ts is ogival). The oxygen tank capacity is 200 m³ (compared to 600 m³ on Blok Ts) with a height of 6.2 m.
The intertank compartment has the same dimensions as the intertank compartment of Blok Ts (diameter 7.7 m, height 5.6 m). Due to the absence of concentrated loads and a decrease in the overall loading level, the design of the compartment is simplified; it does not have pad GSE fittings, Blok A strap-on attachment points, spars and braces. The intertank contains control and telemetry equipment and elements of the pneumatic and hydraulic systems.
The engine compartment has similar dimensions to the cylindrical part of the engine compartment on Blok Ts but differs in its structure. The cylindrical section contains the main attachment points for the Blok A boosters, connected by a frame, with an additional frame halfway up the cylinder. The bottom surface of the cylinder is coated with a heat resistant material. The Blok A attachment points are similar to the ones on a standard Blok Ts. The engine section is a 4.5 m long conical structure reinforced with frames and covered in a heat-resistant coating; 7.7 m diameter at the top, tapering down sharply to 0.5 m at the engine attachment point. A number of cut-outs in the section’s surface make room for pipelines and a boxy structure houses the Blok Ya connection interface.
At the bottom, a single RD-0122 engine is attached, covered by a heat-resistant cowling. The thermal protection materials are similar to those used on Energia. The engine compartment contains the control suite and TVC system for the RD-0122 engine, systems for communicating with the Blok Ya launch table adapter, pneumatic and hydraulic system elements, sensors and control system hardware and elements of the fire and explosion warning system.
The transition compartment is conical in shape with a lower diameter of 7.7 m, tapering down to the diameter of the payload fairing at 6.7 m, and a height of 1.5 m. The design of the compartment is similar to the design of the engine compartment of the Blok V core stage.
RD-0122 engine
The Energia-M core stage used a single RD-0120 engine which was initially the standard unit, but further into development a performance improvement was found if the engine could be throttled down beyond the 45% thrust available on Energia.
The resulting engine, the RD-0122 (sometimes referred to as the RD-0120M) would have been rated for operation at throttle levels as low as 28% nominal thrust. According to Vorontsov, tests conducted at CADB confirmed the possibility of running the RD-0120 at that throttle level. The engines never entered serial production and the Energia-M mockup in the SDI building in Baikonur appears to have a standard RD-0120 installed.
Payload fairing
The payload fairing is similar in geometric contour and design to the Energia cargo container, the GTK (14S70), but shortened to 25 meters. Additionally, it features a truss structure for the attachment of Blok A boosters.
Blok A first stage boosters and RD-170 engines
The Blok A boosters used on Energia-M were identical to the Energia units, 39.4 meters tall and 3.9 meters in diameter. They were fuelled with kerosene and liquid oxygen which fed a four-chamber Energomash RD-170 engine. The engine was also identical to the Energia specification, gimbaling in two orthogonal axes.
Blok Ya launch table adapter
The Blok Ya launch table adapter is what gave the Energia-M its bizarre shape. On the Energia, boosters are offset away from the delicate orbiter to protect it during launch. When a pair of these boosters is removed, the resulting strap-ons sit at an awkward 8 degree angle to the axis of symmetry. For the same reason, Energia-M was sat in the Blok Ya adapter seemingly askew. Despite the looks, this approach maximised the hardware commonality.
Bibliography
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- Gubanov, B., “Triumf i tragediya Energii (Tom 4: Polyot v nebytiye)”, Nizhny Novgorod, 1999, pp. 55–57
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- Lenorovitz, J., “Stockholding Company Proposed To Raise Funds for Energia M”, Aviation Week and Space Technology, 29 June 1992
- “245–25/05–93 Council of Chief Designers to review the work program for the Energia-M and Energia-Buran systems for 1993 and their financing”, NPO Energia, May 25 1993, accessed 31.08.2025