American Institute of Aeronautics and Astronautics

1

Crew Compartments Design and Development for Human Space Transportation and Exploration Vehicles

M. Bottacini, L. Basile, F. Bandini Alenia Spazio S.p.A. - Strada Antica di Collegno, 253 - 10146 Torino - Italy

The development of a pressurized cabin with potential applications on advanced manned space transportation systems is a fundamental step toward the reliable and low cost human access to space. Several studies and preliminary design activities have been performed in the last decade both in Europe and USA on lifting bodies, spaceplanes and capsules for crew transportation (e.g. the Crew Transfer Vehicle or CTV) and rescue (e.g. the Crew Return Vehicle or CRV, the International Space Station Lifeboat). The new space initiative of NASA, addressing the design and development of a Crew Exploration System, modifies significantly the crew transportation scenarios, but allows the reuse of the experience acquired on the earth re-entry systems as far as cabin architecture and crew accommodation is concerned. The parallel need to provide alternatives to the Space Shuttle after 2010 in terms of Crew and Cargo transportation to/from the ISS adds opportunities to the reuse of such experience). The Crew Exploration Vehicle requirements, when compared to the existing human space transportation vehicles performance, ask for improved i) cabin structural life integrity, ii) crew comfort and safety, and iii) operational performance. The above general constraints require a considerable step forward on engineering processes and structures technology and must be challenged with the need for reduced mass and cost.

Alenia Spazio, in cooperation with several Italian research groups, institutes and universities, started in 1999 studies and technology research on a multipurpose pressurized cabin concept (called Crew Cabin Assy or CCA), foreseen for application on the above manned space systems. In addition, preliminary design activities where performed (and are presently ongoing) on several cabin concepts in the frame of ESA program / studies. These activities covered different crew cabin applications, ranging from the initial CRV/CTV concepts down to the more recent Crew Rescue and Transportation Vehicle and Orbital Space Plane.

Presently the Crew Compartments Design and development activities are proceeding in view of their application to the Crew Exploration Vehicle (both for engineering activity and technologies) and in the frame of ESA funded studies / programs concerning the Human Space Transportation Systems (HSTS) and the Cargo Ascent & Return (CARV), both in perspective of Space Shuttle replacement and Crew Exploration Vehicle applications. The paper describes the major achievements up to date and the foreseen further developments, at the light of the new Crew Exploration perspective.

Nomenclature CCA = Crew Cabin Assy CEV = Crew Exploration Vehicle CFRP = Carbon Fiber Reinforced Plastic CRV = Crew Return Vehicle CTV = Crew Transfer Vehicle FSW = Friction Stir Welding HFE = Human Factors Engineering ISS = International Space Station MMI = Man Machine Interface

AIAA/CIRA 13th International Space Planes and Hypersonics Systems and Technologies AIAA 2005-3367

Copyright © 2005 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

Dow

nloa

ded

by S

tanf

ord

Uni

vers

ity o

n O

ctob

er 8

, 201

2 | h

ttp://

arc.

aiaa

.org

| D

OI:

10.

2514

/6.2

005-

3367

American Institute of Aeronautics and Astronautics

2

NDI = Non Destructive Inspection OML = Outer Mold Line OSP = Orbital Space Plane RTM = Resin Transfer Molding SLI = Space Launch Initiative STA = Structural Test Article US = Ultra-Sonic VPPA = Variable Polarity Plasma Arc

I. Introduction HIS document first application foreseen for the engineering and technological activities performed by Alenia Spazio on the CCA, were the CTV and the CRV derived from the NASA Johnson Space Center demonstrator

V201, developed in the frame of the X-38 program. The V-201, as shown in figure 1, is a lifting body whose Outer Mold Line (OML) should have been a constraints for the future developments in the field of the American crew transportation and recovery.

The pressurized cabin study and technologies development should have also considered long-term applications

in the civil and military field, like advanced hypersonic vehicles and new generation systems for reusable, short turnaround manned space transportation.

While the X-38 derived Outer Mold Line forced cabin

shape (see figure 2), engineering studies and technologies were addressed to explore the widest range of applications and solutions, aiming to warranty for all of them: • high performance with a limited impact in mass and

cost; • the maximum degree of commonality in the

mechanical design. The fundamental requirements were a mix of crew

transportation (including also safeguard scenarios) and crew rescue function, both in terms of environments and operational needs.

After the deletion of the NASA CRV and X-38

programs the CCA engineering and technological activities were revised to include the evolving requirements of the Space Launch Initiative (SLI), of the Orbital Space Plane (OSP) and of the Crew Exploration Vehicle (CEV) NASA programs. This program evolution implied the enlargement of the study to different cabin shapes and the assessment on the introduction of additional functions inside of the habitable compartments. Also safety provisions required dedicated assessments and improvements, based on the recommendations issued by the Columbia Accident Investigation Board.

II. Program Logic The CCA preliminary design activities focused on the following major areas of investigation:

• Cabin internal architecture: � Internal layout / configuration; � Human Factors Engineering (HFE) and Man Machine Interface (MMI); � Mock-up;

• CCA Structures; � Primary structure; � Secondary structures; � Thermal analysis;

T

Fig. 1 Concept of X-38 derived CRV

re-entry and propulsion

Dow

nloa

ded

by S

tanf

ord

Uni

vers

ity o

n O

ctob

er 8

, 201

2 | h

ttp://

arc.

aiaa

.org

| D

OI:

10.

2514

/6.2

005-

3367

American Institute of Aeronautics and Astronautics

3

• Harness / avionics integration; • Piping / environmental control integration

The above design activities were supported since the beginning of the program by two major lines of innovation:

• improvement of engineering processes, with acquisition of: � new multidisciplinary databases; � new electronic mock-up for simulation in 0-g, to support ergonomics development; � Virtual Prototyping � integrated and optimized CAD/CAE system; � communication systems allowing the cooperation with international partners in a concurrent engineering

environment. • acquisition of new technologies, forced by:

� the adoption of complex curvatures for an optimum use of the volume inside vehicle OML; � the need for materials and processes ensuring low system mass and good performances both in cold on-orbit

condition and during re-entry.

A strong link between engineering and technology/innovation tasks was mandatory since the beginning of the activities to ensure the achievement of the pursued objectives.

III. CCA Internal Architecture

A. Lifting Bodies

The study of CCA internals started based on CRV/CTV general requirements on crew accommodation, equipment list and X-38 OML. The activities performed were focusing on: • identification of the optimum CCA pressurized shape (figure 2 shows the cabin inside vehicle OML) • study and selection of the equipment allocation inside pressurized structure (the solution identified, based on

multiple equipment “layers” is shown in figure 2); • kind and position of hatches kinematics; cabin

hatches are located on the cabin top (bay 3) and on the side (bay 2) for orbital and ground operability respectively.

• routing of harness and piping on critical areas to ensure layout feasibility;

• investigation on preliminary concepts of secondary structure (see preferred solution in figure 3);

• location of seats and damping system with relevant strokes, as required to meet Dynamic response Index requirements.

Preliminary studies were performed on the X-38

derived CCA potentials for layout evolution toward crew transportation need, maintaining unchanged most of the mechanical architecture (see figure 4). The studies showed a good adaptability, pending a more precise definition of the crew transportation requirements.

The accommodation studies on the 12.5 m3 (441

ft3) CCA showed for rescue and transportation functions the following. • The crew transport capability is of 4 crewmember

to and from the orbit. The volume available per crew member is 2 m3 (∼ 71 ft3). Seats

Fig. 2 CCA layout concept for X-38 derived CRV application, crew of 7

Fig. 3 Secondary structure concept

Dow

nloa

ded

by S

tanf

ord

Uni

vers

ity o

n O

ctob

er 8

, 201

2 | h

ttp://

arc.

aiaa

.org

| D

OI:

10.

2514

/6.2

005-

3367

American Institute of Aeronautics and Astronautics

4

reconfiguration is required to pass from launch to re-entry crew position.

• The rescue version of the layout can accommodate up to 7 crew members, with a volume per crew member of 1.3 m3 (∼ 46 ft3).

Subsequently, in view of the emerging SLI / OSP and eventually CEV requirements, alternative solutions of Crew Cabin Assy were investigated, according to the different entry vehicle concepts investigated. In addition to the Lifting Body X-38 derived, the investigation covered capsule solutions and winged vehicles, both in CRV and CTV/CEV configuration.

B. Capsules

Different Apollo-Viking CCA’s were investigated, with external diameter ranging from 4 m (13.1 ft, compatible with launch inside a fairing) to 5.4 m (17.7 ft, same size of the Ariane 5). Common layout requirements and solutions were used for all concepts, with: • 0.9 m (35 inches) hatches on top (orbital) and on leeward (ground); • Collective seats damping system, with common stroke requirement; • No need for seats reconfiguration during launch and re-entry to cope with acceleration requirements on crew

body; • Updated equipment list (different for crew transportation and crew rescue function) according to capsule needs

and crew number, with related accommodation requirements.

The accommodation studies on Apollo or Viking capsules both for rescue and transportation functions (see fig. 5) showed the following. • The crew transport capability is of 4 crew-

member (6 for the larger size CCA) to and from the orbit. The volume available per crew member is well above the required 2 m3 (∼ 71 ft3) for all concepts investigated.

• The rescue version of the layout can accommodate up to 7 crew members, distributed in two layers inside of the pressurized volume both for 4.4 and 5.4 m option, with a minimum volume per crew member of 1.6 m3 (57 ft3).

This class of vehicles has been deeper investigated because of its natural suitability as Crew Exploration Vehicle

in the last period, having in mind the CEV peculiar layout and configuration constraints.

C. Winged Vehicle Solution

Crew Cabins for larger size winged vehicles were analyzed as well, to assess their suitability w.r.t. OSP requirements. The studies where relevant to crew and equipment accommodation and, thanks to the large volume available, to the possibility to introduce additional functions.

Both Crew Transportation and Crew Rescue requirements

are largely met by this CCA solution, as shown in figure 6. The accommodation studies show that the vehicle can easily carry 4

Fig. 5 Apollo-Viking internal layout assessment (small diameter capsule)

TRANSPORT (CREW OF 4) RESCUE (CREW OF 7)

Fig. 6 Large CCA for Winged Vehicles

Fig. 4 Example of crew accommodation CTV concept

Dow

nloa

ded

by S

tanf

ord

Uni

vers

ity o

n O

ctob

er 8

, 201

2 | h

ttp://

arc.

aiaa

.org

| D

OI:

10.

2514

/6.2

005-

3367

American Institute of Aeronautics and Astronautics

5

to 7 people up and down, performing both transportation and rescue functions in one only vehicle. The system requires seats reconfiguration for landing.

In case of transportation limited to 4 crew members, the large additional volume available can be either

dedicated to: • transportation of additional payload • the introduction of additional functions (e.g. the introduction of an airlock for Extra-Vehicular Activity etc…); • particular safeguard solutions as the ejectable cabin, heavily impacting the CCA design.

D. Human factors

Human Factors Engineering activities supported the definition of the layout. Analytical activities concerned Man Machine Interface, Crew Accommodation & Comfort, visibility,

accessibility and operability of equipment, definition of crew specific components, illumination. Electronic mock-up activities were complemented by

the study, manufacturing and test of a low-fidelity 1-g mock-up of the X-38 derived CRV purposely manufactured. The CCA static mock-up (see figure 7) is comprehensive of complete primary and secondary structure representation, equipment, seats and part of the vehicle aeroshell. The materials used are aluminum for load carrying structures, wood and plastic for other structures and equipment, commercial materials for piping and wiring.

Test activities on the CRV configuration covered the

following major aspects: • equipment accessibility, operability and design

verification; • seat comfort; • seat belts and restraints accessibility, operability; • display Visibility and Accessibility; • hatch Ingress /Egress operability.

IV. CCA Thermo-Mechanical Architecture

Different thermo-mechanical solutions were designed as function of the envisaged manufacturing options (metallic or carbon fiber reinforced plastic). All options provided a load carrying pressure vessel to which the aeroshell is attached.

Figure 8 shows the CCA structural concept for the metallic solution of the X-38 derived CRV, valid in principle

for both aluminum 2219 and aluminum-lithium 2195 solutions. The structure composition foresees a welded pressurized solution composed by 3 bays (4 panels per bay Friction Stir Welded) VPPA welded to T shaped frames and to the rear bulkhead. The other parts of the primary structure are bolted (forward bulkhead, rear dome) or riveted (longerons, stiffeners). The major structural elements (panels, frames, bulkheads) are obtained by forging and machining. An overview of the overall manufacturing process for a metal CCA concept is reported in figure 10.

An equivalent design and analysis effort is being dedicated to solutions more suitable for OSP / CEV applications (e.g. the Apollo-Viking concepts as the one shown in Fig. 9). The activities of preliminary sizing have been completed based on technologies and design principles similar to the ones applied to the Lifting Body. Further activities are in progress for alternative design solutions and alternative material both for the pressure shell and airframe.

Fig. 7 CCA 1-g mock-up (CRV configuration) And 95th percentile male accessibility test

Dow

nloa

ded

by S

tanf

ord

Uni

vers

ity o

n O

ctob

er 8

, 201

2 | h

ttp://

arc.

aiaa

.org

| D

OI:

10.

2514

/6.2

005-

3367

American Institute of Aeronautics and Astronautics

6

• Welded Pressurized Shell � 4 panels per bay (12 total) with

internal waffle (0/90°) 25 mm high and skin thickness of 2.5 mm

� 3 frames (T section) � Bulkhead with waffle (0/90°) 90 mm

high • Longerons • Forward Bulkhead • Dome of the rear bulkhead • Stiffeners of the rear bulkhead • Seals / mechanical connections

Fig. 8 Metallic solution for the CCA – Assembly

PANEL

PANEL

PANEL

PANEL

PANEL

PANEL

PANEL

PANEL

PANEL

FRAME

FRAME

FRAME

FWD BULKHEAD

REAR BULKHEAD

DOME

Equivalent carbon fiber solutions were elaborated by the University La Sapienza of Rome and by Alenia Spazio

jointly. The composite CCA is a concept with separate bays, with six discrete honeycomb panels per bay bonded to the main frames and to the bulkheads. The major structural elements for the carbon solution are obtained using different manufacturing processes. All complex parts like frames and bulkheads are manufactured in RTM and have integral stiffeners. Pressure shell integration requires bonding panel-to-panel and panel-to frame. Longerons are bonded to the shell during the panel-to panel bonding process. Carbon-carbon and carbon-metal joints were designed and analyzed as well.

The preliminary analysis (see fig. 11) showed for all

options a good behavior under the loads experienced during all mission phases. No feasibility issues have been encountered from the analytical point of view for the primary structure options.

IBDM

Tunnel/radial frames

Top plate

Top cone

Middle cylinder

Bottom cone

Spherical cap

Fig. 9 Apollo-Viking CCA Mechanical Concept

Procurement AL 2219 Forging (Panels, Frames, Bulkheads)

Panels Machining

Panel to panel FSW (longitudinal) (separate bays assembly)

Shell bays welding to frames/bulkhead with VPPA circumferential welding

Longerons rivetting

Final assembly

Fig. 10 CCA 1ry structure manufacturing process (metal concept)

Dow

nloa

ded

by S

tanf

ord

Uni

vers

ity o

n O

ctob

er 8

, 201

2 | h

ttp://

arc.

aiaa

.org

| D

OI:

10.

2514

/6.2

005-

3367

American Institute of Aeronautics and Astronautics

7

In view of the overall system level optimization of the pressurized shell-aeroshell- thermal protections & passive

thermal control, preliminary thermal analyses were performed to predict the worst cold and hot CCA temperatures, encountered during the on orbit module operational life and during the re-entry phase. Scope of this analysis was the definition of: • heater power need during the on

orbit crew rescue mission for different CCA - aeroshell interfaces, in order to support the selection of the optimum solution from the system point of view;

• thermal blanket insulation definition;

• structures and equipment temperatures and gradients. The results achieved for the

selected thermo-mechanical design were satisfactory from all points of view, with good design margin on temperature limits and limited heaters power need.

V. TECHNOLOGY DEVELOPMENT

At the beginning of the program the technology development activity investigated a wide range of mechanical architecture critical technology aspects concerning: • light alloys (aluminum 2219 and aluminum-lithium 2195); • composites (evaluated different materials and technologies like Hand Lay-up, Resin Transfer Molding, Fiber

Placement, Filament Winding). After the completion of the first design iteration, technology development activity focused on the following critical aspects.

E. Metal Solution

• The characterization of 2195 aluminum-lithium alloy has been completed thanks to the joint effort of Alenia Spazio and of the research center of the University of Pisa.

• The optimization of 2195 surface protection treatment has been completed. • The development of the Friction Stir Welding process for aluminum

(2219), aluminum-lithium (2195) and hybrid (2219 with 2195) joints is in progress. The activity is being performed on a dedicated FSW pilot plant. Fig. 12 shows welding samples of both Al 2219 and Al 2195. Both Longitudinal and Circumferential Weldings have been investigated with good results. The first step of the process qualification for both Al 2219 and Al 2195 has been completed. The second step, dedicated to fracture mechanics aspects, is in progress.

• The development of the VPPA welding process has been temporarily stopped for Al 2195 and hybrid joints, waiting for FSW development process results.

• The identification of the VPPA welding parameters of 2219 alloy for CCA application has been completed.

• Forming development for complex panel shapes is in progress • The NDI of FSW joints required the acquisition of a US Phase array.

Fig. 11 CCA FEMs (Lifting Body & Capsule

Fig. 12 Friction Stir Welding Samples

Dow

nloa

ded

by S

tanf

ord

Uni

vers

ity o

n O

ctob

er 8

, 201

2 | h

ttp://

arc.

aiaa

.org

| D

OI:

10.

2514

/6.2

005-

3367

American Institute of Aeronautics and Astronautics

8

F. Composite Solution • Physical, chemical and mechanical characterization have been completed by the Research Centers of Alenia

Spazio and of the Politecnico of Turin on the following materials: � Cyanate ester with Intermediate Modulus Fibers; � Epoxy Resins with Intermediate Modulus Fibers; � Cyanate ester Adhesives.

• Manufacturing and test of simple elements has been performed to support structural performance identification and to trim mathematical models.

• Curved sandwich panels manufacturing process has been developed (see figure 13). • A demonstrator of bay has been manufactured to verify the feasibility by hand lay up of a complete elliptical

structure. As shown in figure 14 the manufacturing process resulted to be successful. • The feasibility of CCA parts (bulkheads/frames) with RTM has been verified. The manufacturing and tests of a

technology demonstrator CCA representative with this technique is on hold, waiting for a precise definition of cabin shape.

• Also the manufacturing and test of representative joints is on hold, waiting for the freezing of the CCA.

• New materials, well performing at high temperatures and as such, well suited for the aeroshell manufacturing, have been selected for characterization and development tests. The program foresees the manufacturing of a technology demonstrator of aeroshell parts in composite.

• An air coupled US system for the inspection of the produced parts has been purchased and used for the panels produced.

Fig. 14 Forward bay lamination test article and mandrel (hand lay-up process)

Fig. 13 Curved CFRP panel for CCA pressurized shell (with honeycomb)

Dow

nloa

ded

by S

tanf

ord

Uni

vers

ity o

n O

ctob

er 8

, 201

2 | h

ttp://

arc.

aiaa

.org

| D

OI:

10.

2514

/6.2

005-

3367

American Institute of Aeronautics and Astronautics

9

VI. FUTURE ACTIVITIES

The evolution of the international space scenario, with particular reference to the new space exploration initiative and to the need to replace the Space Shuttle Crew and Cargo Transportation capability, leads to a wide range of potential applications for pressurized shells as the CCA: • Crew and Cargo transportation for Exploration, implying peculiar environments and mission / operational

requirements; • ISS Crew up / down transportation, to ensure the availability of a system alternative to the Soyuz to access the

Space Station after Space Shuttle retirement in 2010; • ISS Cargo transportation; in the present scenario, down Cargo transportation will be ensured after 2010 by the

Progress launched capsule (Raduga) and by the Soyuz, with limited transportation capability.

After a first period of wide range investigations on shapes, modularity and potential for application of the different solutions on each of the above applications, the current development activities are focusing on Apollo-Viking capsule shapes suitable for a high energy re-entry.

The design effort on the CCA thermo-mechanical configuration and design is based on combined CTV/CEV

requirements. The preferred CCA pressure shell and airframe concepts are being deeper analyzed and traded-off, aiming to achieve the optimum from the system level point of view. Some of the previous trades on materials are revisited based on the last available information. The trade-off activities are close to completion.

Also the technologies are being revisited according to the last design results. Additional carbon fiber

development activities for high temperature resistant materials are in progress, while Friction Stir Welding development activities are expected to be completed for end 2005. A complete technology demonstrator of the CCA is under manufacturing. The demonstrator will include joints in Friction Stir Welding, forming of waffle panels with complex shape, carbon airframe parts, and will be representative at the preferred CCA concept.

After the selection of the CTV/CEV concept, the present development and qualification approach foresees the

manufacturing, assembly and test of a structural model of the cabin (Structural Test Article or STA), to support the analytical validation of the structural design with pressure and leakage tests and modal survey.

Further tests (e.g. dynamic tests on structures) are assumed today at integrated system level. The program logic

foresees also the manufacturing, acceptance and supply of mechanical part of the CCA to support the system level qualification process (including flight demonstrators).

VII. CONCLUSIONS

The activities performed for CRV / CTV and OSP / CEV on CCA concepts show for the capsule solutions good potentials both for manned space exploration and ISS crew transfer functions. The results achieved on advanced materials characterization and on improved manufacturing techniques test are promising, and will allow us to satisfy in the best way the demanding CCA requirements. In the meanwhile, the acquired experience is an important background for further developments, opening a wide range of new potential applications. The analysis and selection of the CEV / CTV CCA thermo-mechanical concept is close to completion, and further technology activities are being performed according to the program needs.

The follow-on phases of the CEV program will further refine and certify the CCA design and will support as far

as appropriate the system level development and certification process, up to the delivery of the demo and flight units.

VIII. AKNOWLEDGEMENTS The authors would like to thank the Italian “Ministero delle Attività Produttive”, who made possible the Crew

Cabin Assy program with its major contribution.

Dow

nloa

ded

by S

tanf

ord

Uni

vers

ity o

n O

ctob

er 8

, 201

2 | h

ttp://

arc.

aiaa

.org

| D

OI:

10.

2514

/6.2

005-

3367