Completed SD HLV assessment highlights low-cost post-shuttle solution

by Chris Bergin

The Shuttle Derived Heavy-Lift Launch Vehicle (SD HLV) Assessment has been completed, the result of applying years of historical expertise from members of the Space Shuttle Program (SSP) and others into a follow-on vehicle. The focused effort over 15 months to create a post-shuttle masterplan has fostered HLV options that could be completed to a Block II Full Operational Capability for around $7.8 billion.


Numerous studies into a follow-on replacement for the Space Shuttle – which utilizes the hardware, infrastructure and skill set workforce – have been created and presented over recent years, mainly based around two concepts; an inline launch vehicle and a sidemount vehicle.

Such studies range back to before the Vision for Space Exploration (VSE) – which ultimately decided on the 1.5 architecture of Ares I and Ares V, via the 2005 ESAS (Exploration Systems Architecture Study).

Alternatives to the Ares approach included the unofficial, yet highly public Direct team effort on a Jupiter Inline family of launchers and architectures, and an official – but behind the scenes – Sidemount effort, which became a larger team effort in late 2008.

SSP manager John Shannon was able to publicly present the status of the preliminary Sidemount effort to the Augustine Committee’s review into Human Space Flight in 2009, covering a variety of disciplines, even as engineers continued to add and refine the Sidemount system.

In late 2009, Mr Shannon requested the Inline SD HLV to be included in the analysis to provide a comparison with the Sidemount system. Sources note the Inline systems were developed independently by Mr Shannon’s team, as opposed to directly using the Jupiter vehicle blueprints, despite meetings between NASA officials and the Direct team members, and the great similarity between the architecture.

NASA also requested for a trade study (HLLV Study) to be carried out on the HLV options, notably between the RP-1 booster, Sidemount and Inline systems.  The SSP Assessment effort, however, ran independent of that study, but provided input.

Work continued in earnest until President Obama’s 2011 budget was unveiled in February, which proposed the cancellation of the Constellation Program (CxP), but also the use of Shuttle-derived systems, with SSP given notice to shut down their HLV study activities by completing the documentation of their findings.

The documented effort on the SD HLV was completed this month, resulting in an impressive – and highly extensive – 726 page presentation, which was acquired by L2.

“This document describes the pre-Phase A concept definition, studies, and analysis results generated by the Space Shuttle Program on various Shuttle-derived Heavy-lift Launch Vehicle (HLV) concepts over a 15-month timeframe from December, 2008 through February, 2010,” noted Mr Shannon in the foreword of the presentation, dated June 8.”

“The work was performed in response to questions from the 2008 Presidential Transition Team, the Augustine Committee’s ‘Review of United States Human Space Flight Plans,’ and a 2009 internal NASA assessment of Heavy-lift Vehicles. Subsequent to the release of the President’s proposed FY2011 budget in February 2010, HLV assessment activity was halted and effort began to document the preliminary results.

“This document reflects the hard work and dedication of individuals representing the Space Shuttle Program and its contractor community. The contributions of this team have contributed to the Agency’s understanding of Heavy-lift Vehicles and are greatly appreciated.”

“When the HLV assessment was stopped, some work was left unfinished, as noted by the inconsistency in detail found in the various sections. Results documented in this document should be considered similar to a Pre-Phase A collection of concept studies. A sound project formulation activity would be required to add necessary detail.”

“This document is under configuration control of the Space Shuttle Program… to preserve the knowledge developed by the subject activity.”

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A Smooth Transition:

The focus of the assessment – which concentrates on the Sidemount option – is based around a block transition of existing Shuttle hardware, for early flights using remaining assets left over after Shuttle, prior to the upgrading via new hardware and software.

“Shuttle derived is the dominating factor that sets these studies apart from other similar assessments. This objective was to maximize the use of existing Space Shuttle skills and assets for developing and operating the HLV. This includes using the flight hardware, the flight software, the facilities, the processes and the skilled contractor and civil servant personnel that have been used successfully on the Space Shuttle,” noted the Executive Summary.

“A block development approach was adopted to provide the earliest possible capability at the lowest cost and risk, and then evolve that capability over time. Block I uses the residual Shuttle flight hardware with little or no modifications, while Block II would replace the Shuttle subsystems and elements with new hardware and software when the existing assets ran out.”

As previously noted in memos on the ongoing studies, hardware availability allowed for the potential for around three flights of the Block I SD HLV. Extensive outlines on the actual stock count of SD hardware is provided later in the presentation.

“The existing inventory of the certified flight hardware is sufficient to support three or more flights after the Shuttle’s planned retirement. The only major new development for Block I would be the Payload Carrier (PLC) that replaces the Orbiter on the side of the External Tank (ET),” the summary continued.

“Block III upgrades could be done later to increase performance and reduce launch costs to support NASA’s future needs.”

Also key to the findings, the proposed HLV is part of a larger mission architecture, one which could provide additional support for the International Space Station (ISS) if required, mainly via cargo capability, but also via crewed versions of the vehicle, and on to Lunar mission support and beyond.

The presentation also noted that the crewed HLV version would utilize the Orion in its original role of transporting astronauts into orbit and back, as opposed to the FY2011 proposal of an interim role only as a Crew Rescue Vehicle (CRV) on the ISS.

“The HLV is primarily for cargo and provides an excellent foundational capability for heavy-lift. It can deliver 80 metric tons (mt) of gross cargo to Low Earth Orbit (LEO), 45 mt to the International Space Station (ISS), 30 mt to Geosynchronous Orbit (GEO) and 8-10mt to the lunar surface.

“A capsule such as the Orion Crew Exploration Vehicle (CEV) can be added to the top of the PLC to carry crew to the ISS or do manned lunar or other crewed missions. A Launch Abort System (LAS) can be added to this crewed configuration which would significantly improve the estimated loss of crew (LOC) rate by a factor of 5 to 10 compared to the current Space Shuttle.”

“The goal was to have the HLV ready and tested prior to the planned Orion completion so it could be used as a crewed launch vehicle or as a backup for a commercial crewed launch vehicle.”

The Executive Summary also reported the findings that the Inline version of a SD HLV is at a disadvantage to the Sidemount, based on schedule and cost and degree of infrastructure changes. However, while the presentation focuses mainly on the Sidemount, due to the late start to the Inline study, both versions – along with the potential to start with Sidemount, before merging into an Inline vehicle – are deemed to be feasible.

“Late in the HLV concept definition studies, the HLV team was asked to evaluate an inline Shuttle derived HLV development with same approach and strategy to use existing Shuttle assets and compare those results to the side mount HLV,” continued the Executive Study.

“The in-line HLV performance results were very similar to the side mount HLV since using the same number of Solid Rocket Booster (SRB) segments, the same number of Space Shuttle Main Engines (SSME) and propellant loads were basically the same. Block I development would take about two years or longer than the side mount.

“Building the PLC for the side mount and adding a new thrust structure to house the SSME’s on the bottom of the ET for the in-line core stage would be a wash. The largest difference would be that the launch pad and the mobile launch platform (MLP) would require a launch tower for the taller in-line vehicle and considerable changes to the MLP and the Tail Service Mast (TSM) configuration.

“These additional changes for the in-line HLV could take longer and would cost more than the side mount. This document contains more information for the side mount than the in-line HLV due to the late start on the inline.”

“Both are feasible and could provide a heavy-lift capability much sooner than a new heavy-lift launch vehicle. A viable option (no cost analysis yet) could be to start with the side mount first then evolve to an in-line HLV if and when needed.”

The summary also noted what is arguably the most attractive elements of a SD HLV-based transition; schedule, cost, and skillsets. Operational proficiency , a key aspect in flying safely and minimizing the gap in the current SSP operations team, is a critical driver and very perishable. Loosing the critical skills only to hire and train a new team seven years in the future could be very disruptive.

“These studies identified some major advantages in pursuing a Shuttle derived HLV capability as soon as possible. First, it retains the Shuttle infrastructure and critical skills needed to fill the gap in our nation’s human launch capability, and maintaining the United States’ leadership in space exploration.

“Second, it would provide a foundational heavy-lift launch capability that could support maintenance and growth for the ISS, it could be used to develop a propellant resupply depot in space, and it could be used to demonstrate critical subsystems and elements that would expand or raise the technology readiness level for future deep space operations. It could also support flexible path missions beyond LEO that would be building blocks and validate the systems needed to eventually go to Mars.”

“The primary advantage is that the Shuttle derived HLV provides a foundational heavy-lift capability soon, at affordable costs and relatively low risk, thus enabling meaningful development and space operations missions while providing the time and resources to develop the technologies and systems to meet our future space exploration needs.”

Interestingly, while the study team’s primary goal is to document the findings of the extensive studies, as opposed to enacting an effort that is currently opposed by the FY2011 proposal, an element of hope is noted for the documentation to become the basis of a commercial proposal for a HLV that would fit into President Obama’s outline for NASA’s future.

“The intent in documenting the results of these HLV concept definition studies and analyses is to make this wealth of information available to the Shuttle contractors and the commercial space systems development and operations community to meet our country’s space exploration needs,” the summary added.

“We encourage the use of this data to support a commercial venture that would own and operate a Shuttle derived HLV system. Commercial ownership and operation of such a Shuttle derived HLV system may be a practical way to significantly reduce the operating costs to fly the current Space Shuttle while providing a near term, low risk heavy-lift capability for our national space program.”

Sidemount SD HLV:

With history back as far as the Shuttle-C concept, the Sidemount HLV is the most natural of the transitions from the STS design.

“The side mount HLV make extensive use of legacy Space Shuttle assets. The primary ascent elements of the SSP [ET, RSRB, SSME] are unchanged from their current configuration,” outlined the presentation.

“The main propulsion module is connected to the ET in the same manner as the Shuttle except there is no requirement for disconnects as the module remains attached to the ET after main engine cutoff. The avionics and software of the Orbiter will be virtually unchanged from their current configuration and functions, and are to be mounted in either the HLV aft propulsion module or distributed on the Payload Carrier (PLC).”

The first flight of the Sidemount HLV would have utilized the spare ET-94 tank, currently housed at the Michoud Assembly Facility (MAF) in New Orleans. This tank is a LWT (Light Weight Tank) as opposed to the SLWT (Super Light Weight Tanks) currently used by the Shuttle to achieve larger masses to be carried uphill.

“The earliest flight configuration of the side mount HLV could use an existing Lightweight External Tank (ET-94) and a propulsion module boat tail based on the existing Shuttle design. Later versions of side mount HLV would use Super Lightweight Tanks (SLWT) and a new design boat tail housing the SSMEs.”

“The primary new element is the Payload Carrier with a payload envelope of 7.5-m x 30-m. The selection of a 7.5-m diameter was picked as the latest practical diameter that support future missions. Further analysis has shifted the focus to smaller lander designs for lunar orbit rendezvous missions and EDS designs based on a cluster of RL-10 class engines.

“While such later designs could be accommodated using a 6.5-m diameter Payload Carrier, it was decided to retain the larger diameter for future mission growth. Fairing elements of the Payload Carrier are jettisoned during the ascent to increase payload capabilities.”

Analysis of the use of a propulsion/avionics module was also conducted to provide a future option to recover “high value assets” following launch of the HLV – namely the SSME engine systems and avionics.

“Because the staging point of the SSME propulsion is around Mach 17 for a J-2X upper stage or Mach 24 for an RL-10 upper stage, the module would reenter and land in the Atlantic Ocean.

Inline SD HLV:

As referenced by the Direct Team’s Jupiter Inline vehicle concepts, this design also has a history reaching back as far as the Marshall Space Flight Center (MSFC) studies (1990s) to design a shuttle-based heavy lift cargo vehicle to compliment the Space Shuttle. Known as the National Launch System (NLS), the concept was deemed to have significant merit – before being deleted due to budgetary concerns.

“The SSMEs and RSRBs are used unchanged. The propulsion module is positioned at the aft end of the in-line tank and the payload carrier is placed in-line above the tank,” noted the presentation on both commonality and changes. “Because of the axial and bending loads the in-line tank requires strengthening beyond that of a standard External Tank design.

“In addition the forward LOX tank is redesigned from the ogive shape of the External Tank to a cylindrical tank section with elliptical domes.

“There are more extensive changes to the Mobile Launch Platform, Fixed and Rotating Service Structures, and tail service masts to accommodate the taller in-line configuration. There are also significant changes in the Vehicle Assembly Building (VAB) to assembly and servicing platforms. Payload fairings are jettisoned on the way to orbit to increase payload capabilities.”

A fascinating mitigation of numerous infrastructure challenges would be to place the SSMEs/MPS on the side of the Inline vehicle, which would mirror the STS aft end on the current MLP and Pad.

“An alternative HLV configuration was also examined late in the study period. This hybrid concept uses an in-line mounting of the payload at the upper end of the in-line Shuttle derived tank, but retains the SSME engine placement in the side mount position as on the Shuttle.

“The intent was to define a low-cost, interim flight demonstration vehicle that allowed use of an existing External Tank and minimized infrastructure changes especially at the MLP.

However, this concept also has challenges of its own, such as offloading propellants during a pad abort, and axial and bending loads on the intertank region.

“A notional extensibility approach for operational vehicles using this hybrid concept is shown (in the graphic – left). The advantages include reducing the number of changes to the launch pad and also providing for easier detachment of the propulsion modules when used in conjunction with the recovery module concept presented (see reference in Sidemount overview).”

Upper Stages:

Suborbital staging to increase payload capabilities is a charge that has sometimes been cited in opposition to the ESAS findings, which – mainly due to the restrictive timeline of the study – was deemed to have only made a cursory examination of the SD HLV options, notably Sidemount.

The design of the Upper Stage is a key element to the ability of the HLV, to conduct the mission of interest.

“The HLV has the capability of taking large cargo to an orbital or suborbital stage point. For a useful mission this cargo must contain the propulsion necessary to carry payloads to a final destination. This propulsion element may be integrated with the payload, but usually takes the form of an upper stage. Examples of upper stages include existing and new designs.

“Early deployment of payloads to LEO or beyond LEO using Block I HLV could utilize existing stages such as the Delta IV or Atlas V upper stages. Such stages could support demonstration missions such as a lunar swing-by Orion test mission or GEO deployment of a Space-based Solar Power Satellite demonstrator.”

“Block II and Block III HLV would also use new design upper stages based on various rocket engines including J-2X and the RL-10 family.”

Engineers went back further into the history of the program for the Upper Stage evaluations, referencing the engine used during the Apollo era.

“Existing systems were compared against mission needs and the original Apollo upper stage, the S-IVB, to highlight attributes of a successful configuration.

“By taking this approach, the development of a fully integrated HLV flight system is possible that maximizes the application, with minimal redesign, of the Shuttle elements which remain in near-term production while replacing those elements – with the exception of the Payload Carrier – that are not in production with those derived from existing Evolved Expendable Launch Vehicle (EELV) systems.”

“This creates an overall vehicle capable of high performance, but with minimal development time and cost. A smaller and simpler upper stage derived from commercial experience also eliminates a large measure of the upper stage propulsion, avionics and systemic development efforts and refocuses those efforts on tailoring a stage uniquely suited to the requirements of a Shuttle derived Heavy-lift Launch Vehicle.”

The Block I, II, III approach:

The three block approach would apply to both the Sidemount and Inline vehicles, a building block design approach that was determined as the best way to minimize cost and utilize Shuttle assets. There are three blocks in total, with Block I including a Proto Demo Test Flight for the in-line configuration.

“The Block I HLV utilizes existing Shuttle assets wherever practical. The first flights are based on a large inventory of existing assets including RSRB, ET, SSMEs, avionics and software and other subsystems. The RSRBs are used unchanged,” the presentation outlined.

“For side mount HLV the External Tank is unchanged except for minor modifications to ET bipod and thermal protection in targeted areas. Block I inline HLV will require a development effort for the in-line tank. Legacy SSMEs are housed in the propulsion module structure based on the existing Shuttle boat tail for the side mount HLV or on a new design for the in-line configurations.”

“Shuttle avionics and software and other applicable subsystems (e.g. APU, RCS) are modified or used unchanged. A new payload carrier with jettisonable fairings is developed. Existing upper stages may be used for various mission types.”

“Block II HLV: New production expendable SSMEs are used. These SSME are routinely run at 109 percent power level during ascent which will necessitate several minor modifications to the MPS (e.g. LH2 feedline flowliners, GO2/GH2 flow control valve orifices, etc.). The side mount ET has further strengthening in localized ring frame areas. A new design side mount propulsion module replaces the Shuttle boat tail design.”

“The payload carrier design for cargo is modified for crew. Improved subsystems (non-toxic propellants, electromechanical actuators, etc) are used. Crew capability is provided using the Orion spacecraft with Launch Abort System. Provided are new avionics computers with emulation of current Shuttle computer architecture allowing current flight software to be used with little modification and low risk.”

“For larger payload flights beyond LEO a new Earth Departure Stage (EDS) is developed. Initially the J-2X engine from the Constellation program was baselined. However, later trade studies showed that an EDS based on RL-10 engines provided a lower mass and higher payload solution for missions beyond LEO.”

“Block III HLV: To maximize payload to orbit, the Block III HLV uses four SSMEs housed in a reconfigured propulsion module design. These expendable SSMEs are routinely run at 111 percent power level during ascent. Significant modifications to the MPS will be needed to accommodate this configuration. The 4-segment RSRBs are replaced by 5-segment RSRBs for higher thrust.”

“The External Tank or in-line tanks are lengthened to accommodate a higher propellant load. The EDS from Block II also has increased propellant capacity tanks. This results in a 33 percent increase in payload capability over Block II.”

Available Assets from STS:

A large effort was placed into inventory analysis of existing and required systems for – at the very least – the Block I flights, along with ground rules and associated costs and procedures on contract awards. Key areas – such as available ET, SSME and SRB hardware – provided an interesting status review of overflow STS assets.

“SSMEs: The SSME Project Office presented to the Shuttle derived Heavy-lift Launch Vehicle (SD HLV) team on two occasions. The Pratt & Whitney designation for the current configuration SSME is RS-25D,” noted the presentation.”

“The first SSME Project Office presentation to the HLV team occurred on August 21, 2009. This briefing was in response to questions from the HLV team attempting to validate a cost analysis performed at the request of the HLV team. The SSME Project was asked to assess the reasonableness of the cost estimate as well as its associated assumptions.”

“The SSME Project determined the cost estimate to be reasonable with the following two exceptions: a. The estimate lacked sufficient funds to provide for tooling and infrastructure investments necessary to meet 15 engine per-year production goals. The SSME Project recommended adding 125 million dollars for capital investments. b. The estimate lacked sufficient funds to provide for design, development and certification costs. The SSME Project office recommended adding funds.”

“The SSME project recommended maintaining the current concept of operations for RS-25 fabrication, assembly, test and delivery. In this process, line replaceable units (LRUs) are completed by PWR and shipped to Kennedy Space Center (KSC) for engine assembly. Assembled engines are then shipped to Stennis Space Center (SSC) for acceptance testing, after which they are shipped back to KSC for installation and flight processing.”

A reference is also made to a decision that was noted by the all-powerful Program Requirements Control Board (PRCB) meeting in January of this year, where a proposal was put forward to delay the disposal of SSME assets, pending ‘future launch vehicle architecture’ decisions, which – as per the SD HLV presentation – now appears to have been an extension to the ‘feasibility’ of SSME production restart.

“At the time of the briefing, SSME production restart was feasible. The assessment determined that in-house tooling and critical skills were still available to enable restart. Further, the majority of vendors were still available. However, some vendor restart funds would be required. It was determined that the Space Shuttle Transition and Retirement activity posed a significant risk to potential future RS-25 production,” the SD HLV presentation added, before noting flight rate demands.”

“Two potential design changes were presented as necessary. The current RS-25 main combustion chamber would likely be replaced with a Hot Isostatic Pressing (Hip) Bonded MCC to help meet production rate goals. The current engine controller would be replaced after the current inventory was depleted. The current controller is made of electronic parts which are not currently available. Therefore a new design would be required.”

“The HLV team proposed a flight rate which would require up to 15 RS-25 engines per year. Heritage RS-25 production has not emphasized delivery schedule for many years. Rather, production was driven by funding and other resources demands. This brings into question the use of historical production actuals as the basis for estimates in a high-production rate environment. This further illustrates that caution should be used when doing so to ensure valid estimates.”

In total, 15 SSMEs are expected to be available at the end of the current Shuttle manifest, along with two development engines.

“Projections at the time of the briefing indicated that 15 current configuration (Block II) RS-25D flight engines would be available at the end of the current SSP manifest which included flights through STS-134. Additionally, 2 development engines would also be available. This projection included completion and acceptance testing of engine 2062 and 4 high-pressure turbopump recycles which were unfunded at the time of the briefing.”

A reference is also made to a new version of the SSME, called the RS-25E, which aids the HLV benefits via lower costs.

“The RS-25E design consists of design and process changes necessary to lower the per-unit cost as well as decrease the required production cycle time. An attempt was made to strike a balance between retaining current RS-25D reliability, while sufficiently improving cost and fabrication time with minimal design, development and certification requirements.”

“The previous end of program forecast indicated that 15 legacy flight RS-25Ds and 2 development RS-25Ds would be available. The recommendation to the HLV team was to assume 12 HLV flight ready RS-25D assets. This would provide 3 flight and 2 development engines for RS-25E development and certification testing, as well as stage/main propulsion test article (MPTA) testing.”

“The RS-25E engine is the next evolution of the RS-25 engine. It is intended to incorporate changes to reduce fabrication time and cost while retaining legacy RS-25 reliability and history. It leverages technology utilized on other engine programs as well as incorporates recent lessons learned in RS-25 production.”

With the Block I HLV utilizing the current four segment design SRB/RSRM, minimal impact is noted for ATK to support the transition. Also, the Block I flight profile mirrors the Shuttle, allowing for minimal changes to elements such as avionics and recovery systems.

“Solid Rocket Boosters and Reusable Solid Rocket Motors: The current Space Shuttle Program (SSP) four-segment Solid Rocket Boosters will be able to support the Shuttle derived Heavy-lift Launch Vehicle.’s (HLV) initial Block I mission requirements with minimal impact.”

“The Block I flight trajectories and staging parameters are within the SSP design profiles. Given the ground rule that HLV will communicate with SRB avionics for GN&C and separation staging exactly like SSP, SRB avionics systems will not require modification. Since the staging conditions (altitude, velocity, flight path angle, etc) are within SSP design conditions, no changes will be needed to SRB recovery systems.”

“However, as the development of design loads for SSME buildup and abort shutdown matures, high loads for the on-pad conditions may lead to SRB aft assembly (motor case, skirt) buckling issues. This may require a static structural test to demonstrate ultimate factor of safety requirements can be met, and possibly some local structural modifications.”

“All existing systems and subsystems will certainly require an analytical recertification to a new set of HLV-based design loads and environments.”

The buckling issues are also referenced for the Block II vehicle, which may become worse if the transition to a five segment SRB is taken for the upgraded HLV.

“For the follow-on Block II phase the only avionics box of concern is the Integrated Electronic Assembly (IEA), which has not been upgraded since STS-1. All other avionics have been upgraded. The two IEA.’s are located in the Forward Skirt and Aft ET/SRB Attach Ring and provide the primary electrical interface to the Orbiter managing a multitude of operational functions. These units will have to upgraded at some point depending on the mission model along with their ground test and checkout equipment.”

“If five-segment solid rocket motors are required for heavier lift purposes, on-pad loads for SSME buildup and abort shutdown become a bigger concern. Preliminary estimates indicate loads increases of ~18-23% for the aft booster assembly. This would impact the aft motor case joints, case buckling limits, and the aft skirt. A significant analysis effort would be required to determine if there is adequate structural margin and a structural test would be a certainty.

“All other systems and subsystems would be able to support this vehicle concept unchanged.”

One subject which has already been covered extensively – due to the previous Shuttle Extension studies – was the spare External Tank inventory. As previously know, several spare tanks are at various stages of production. However, the HLV presentation documents their build-state for the first time.

“External Tanks: There are numerous External Tank assets that could be used for a Shuttle derived sidemount HLV. Manufacturing processes require 1) people, 2) processes, and 3) parts,” noted the presentation.”

“Due to Space Shuttle Program Completion, some of the people and processes used to manufacture an External Tank have been lost. For example, External Tank welding and mechanical assembly processes have been shut down and the skilled personnel utilized in these processes have been lost.”

“However, there are numerous parts used to build an ET that are available for continued ET production in support of side mount HLV.”

“At the completion of the SSP there will be one remaining certified flight tank, ET-122. This tank is the Launch-on-Need (LON) for the last scheduled flight of the SSP. ET-94 is another flight article that is available for HLV. However, it is not in flight status and it would require significant repair activities to certify it for flight. The structural members of ET-94 (liquid oxygen tank, liquid hydrogen tank, and intertank) can be utilized for a flight article.”

“There are other External Tank work-in-process assets that will be available for flight. The additional assets were produced during the SSP extension activity in FY09. Additional flight hardware was procured by Lockheed Martin to support the original requirements of the current External Tank contract.”

The graphic confirms ET-139 is at an advanced stage of structural completion, especially compared to ET-140 and ET-141. Also, the key driver to the delivery of a new external tanks – claimed to be as late as 2013, due to the certification of a new Thermal Protection System (TPS) foam – BX-265 – is nowhere to be seen in the HLV documentation.

Depth of Analysis:

Huge amounts of data are presented via computational models and analysis, based mainly around the cargo and manned versions of the Sidemount HLV.

“A payload separation assessment methodology was developed for the Heavy-lift Launch Vehicle (HLV) configuration based on Shuttle heritage sequencing and body rates at MECO,” was one such example of the evaluations. “Several studies using this methodology were done to assess the separation dynamics of the HLV. Two different payloads were studied; one consisting of only a barge, and another that included a crew capsule based on the Orion design.”

Other bodies were also brought in to lend their experience to the assessment, such as the Aeroscience and Flight Mechanics Division, who supported the on-pad and in-flight aborts for an Orion crew vehicle riding with the Sidemount HLV.

Several references are made to the three-degrees-of freedom Program to Optimize Simulated Trajectories (3DOF/POST) analysis methodology, which is an industry standard, again thinking in advance to a potential transition of the SD HLV concepts to a commercial company.

The Langley Research Center (LaRC) were also tasked with aiding analysis on pad aborts for the HLV married with Orion – gaining another large set of data points in the presentation.

The experience of the SSP workforce – who have effectively flown a version of the SD HLV via the STS over 130 times – can be seen throughout the presentation, with available computational and historical models on elements such as the External Tank providing accurate data points for expected conditions for the HLV.


The experience base with STS also comes into play with the costings of the vehicle, with the HLV development and recurring cost estimates are based on the actual historical costs for the same elements used by the Space Shuttle Program, with complexity factors applied to modifications of existing subsystems that are similar to those currently used on the Shuttle, and engineering estimates for the new developmental items.

“Since these cost estimates are anchored to well-defined historical data, they should have higher confidence levels than similar cost estimates for new developmental launchers,” opened another extensive element to the presentation.

“The major new development element for side mount Block I HLV is the Payload Carrier which includes the Payload Shroud, Strong Back Keel, and Boat Tail containing the propulsion, power, and avionics subsystems. For the for side mount Block II HLV, the major development items include a lower cost, RS-25E variant of the SSME, a new avionics and software suite, non-toxic electric APU, EMA-driven MPS cryo valves, and the EDS.

“Production of duplicate MPS LH2 and LO2 feedlines are also significant longlead items. To mitigate cost estimating uncertainties, a 30 percent Contingency Factor was applied to the DDT&E costs for the new HLV elements and 10% for recurring costs.”

The cost estimate, the figure which is one of the key points of support for a transition to SD HLV, comes in at $7.8 billion dollars to get to the point of FOC (Full Operational Capability) of a Block II HLV, a fraction of the cost of Ares. To get to Block I first flight the development cost is only $2.7B.

“Figure 3-77 shows the estimated funding profile for the side mount HLV development program for both the Block I and Block II configurations over a 6 year timeframe. This would be the budget required to develop the HLV assuming full funding each year starting in FY11, including the effects of inflation at a rate of 3.0 percent per year.”

“The total side mount HLV development cost to reach a full operational capability was estimated to be $7.8 billion (plus about $1B cost to develop the EDS), with an overall development period through Block II of 72 months. The Side Mount HLV development costs are estimated to be less than $8B for the initial Block I plus the upgrades to Block II.

“These launcher development costs do not include the EDS which was considered part of the payload. The peak vehicle funding requirement of $1.5 B would occur in the fourth year of the development program. KSC infrastructure costs were not included. “

Once developed to FOC, the estimated reoccurring cost of the HLV varies between a NASA run and a commercially run vehicle (and/or a NASA/Commercial co-effort). A flight rate of six launches per year is used in the example.

“At a flight rate of 6 launches per year, the estimated cost for each HLV launch would be $600M (fixed year $2009), once the side mount Block II HLV has become fully operational. The bottom (green) curve would apply to a fully privatized management approach, reflecting the significant recurring cost reductions possible by operating HLV on a commercial launch services basis.

“These cost reductions result from utilizing standard aerospace commercial processes to streamline the contractor program management, sustaining engineering, production, and operations costs, along with minimizing the institutional and other direct costs associated with NASA oversight.

“Contractor & NASA skill bases would be merged; there would be reduced reserves, facilities efficiencies, and commercial production efficiencies. NASA would provide Baseline anchor tenancy and there would be limited liability. At a flight rate of 6 launches per year, the HLV recurring cost is about $450M per flight.”

The Inline estimates show where Sidemount holds an advantage, although the presentation cites an in-line HLV development program for the Proto-Demo, Block I, and Block II and Block III configurations over a 12 year timeframe.

“This would be the budget required to develop the in-line HLV assuming full funding each year starting in FY11, including the effects of inflation at a rate of 3.0 percent per year. The total in-line HLV development cost to reach a full operational capability was estimated to be just under 15 billion dollars, including the cost to modify the ground operations facilities at KSC and the cost to develop the EDS.

“The peak funding requirement of $2.5 B would occur in the fifth year of the development program.”

The total cost of $14.9 billion is placed into context when the costs to Block III for the Sidemount SD HLV is shown, with the presentation citing a total cost of $11.2 billion up to – and including – FY2020.


The bottom line for the availability of the Sidemount HLV shows the first flight of the Block I in FY2015, with Block II’s first flight in FY2017. The Block II version of the Inline HLV is cited as FY2019.

“By utilizing existing, high-confidence Shuttle flight hardware, software, and facilities, the HLV could become operational sooner than any other heavy-lift alternatives. Figure 3-86 shows the development and operations schedule for the Block I and Block II versions of the side mount HLV.”

“The Block I version would take advantage of existing inventory of Shuttle assets to minimize the time to first flight, lower development risks, and reduce costs. The Block II version would replace the existing Shuttle elements and subsystems with newer, lower cost technologies as existing inventories are consumed.

“Because many flight-proven Shuttle elements are used largely unchanged (RSRBs, External Tank, SSME, subsystems), the development can be expected to proceed rapidly. Reuse of existing flight software precludes an entire software development effort, which often becomes the schedule driver in new development projects.

“The major development item for the Block I configuration would be the Payload Carrier which includes a large Shroud, Strong Back Keel structure, and a Boat Tail with propulsion, power, and avionics subsystems. Estimates of the STS Program inventories indicate there would be sufficient residual Shuttle hardware to support 3 to 5 Block I HLV flights, depending on the subsystem.

“The development of Block II subsystems would be done in parallel with the Block I development program, and the Block II upgrades would be introduced into the flight configuration when that subsystem’s residual inventory is exhausted. The pacing item for the Block II sidemount HLV would be the 72 months to develop and certify the lower cost, RS-25E variant of the SSME.”

Notably, the infamous schedule “Top Risks” show no RED concerns, unlike the latter years of Ares, which was plagued by numerous RED concerns in schedule Top Risks, ultimately playing a role in its proposed demise.

The next article will cover the mission profiles a SD HLV would be tasked with, from ISS to Lunar.

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