Aircraft and Rockets

JUNICHI MAEZAWAMINORU KOBAYASHI

Courtesy of NASDA

taking opportunities to steadily enhance its technical capabilities towards being able to produce entire aircraftin the fixed wing aircraft field.
In the same way, MHI intends to increase its technical capability in the space industry towards achieving
the integration of launch vehicles (rockets), seizing the
major opportunity presented with the transfer of the
H-IIA to the private sector. Further, in the utilizationof space, namely the final purpose of launching rockets
that serve only as a means of transportation, it is important that MHI develop space system-integrating
technology such as space solar power systems, and satisfy various social needs such as supplying clean energy.
In order to realize true progress in the aerospace business, it is essential for MHI to strive in such a way thatthe systemization and the integration of its products
support customers. This report introduces trends of aircraft and space products such as rocket vehicles that are
major products of MHI’s aerospace business, with an
overview of past, present, and future perspectives of theaerospace products. Some products and technologies aredescribed in detail.

1. Introduction.
.

There are two basic types of demand in the aerospace
field, as described below.
Demand for transportation systems, including distribution systems
Demand for air defense systems related to national
defense and security
The former type of demand is related to the infrastructure for transportation supporting the globalizationof the world economy, while the latter concerns the provision of security as a premise for the growth of the global
economy. It is essential to establish a good relationshipbetween the former and the latter. Moreover, from theperspective of changing circumstances in the world after September 11, 2001, it has become necessary to make“globalization and rationalization” and “security” compatible with each other for the future world. From thisviewpoint, aerospace products will become increasingly
important, because they are major components of theseinfrastructures.
It is necessary for effective transportation and security that the systemization and the integration of
products and services should be the goal.
As the defense industries, it is necessary to establish
not only a combat aircraft system itself but also a total
air defense system that enables each defense element tooperate efficiently and effectively for national defense
and security by utilizing the latest information technology. Therefore, system integration and its technicalelements must be developed to realize the ultimate needsof national defense and security effectively.
In the civil aircraft industry, MHI has expanded its
business activities by selling its products to aircraft
manufacturers such as Boeing Company and Bombardier Inc. In the future, MHI also intends to strengthen
its business to make that business bigger, so as to sell
its products directly to aircraft users who are the end
users of the products. MHI has already opened the door
towards achieving this goal through the introduction of
the MH2000 in the helicopter field. MHI is seeking and

2. Progress of aircraft technology in Japan
Aircraft enterprises in Japan were revived after WorldWar II to support U.S. Air Force aircraft maintenance.
Then we learned the manufacturing methods and technology for post-war aircraft through licensed production
for Japan Defense Agency. Based on that experience,
the basis for designing and manufacturing our own civil
aircraft has been established. Our business has grownto undertake the production of large components suchas wings and fuselages for U.S. companies. And, ourlevel has reached the stage where we developed the F-2
fighter in cooperation with the U.S. Nowadays, the largescale civil aircraft market is dominated by two major
aerospace powers in U.S. and Europe, while other foreign enterprises have recently spread participation morein this civil aircraft market by supplying aircraft subsystems and components. It is obvious that competition
for production share is becoming very tight. That is why
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MHI must extend its ability for designing and manufacturing in this aerospace fields.
2.1 Trends of MHI products ( Table 1
1)
The full-scale aircraft business of MHI began with thelicensed production of F-86F fighters, which was soon
followed by the licensed production of F104J supersonicfighters in the 1960s. Through the domestic developmentof T-2 supersonic trainers and F-1 supersonic fighters in
the 1970s, MHI subsequently gained expertise in the design of supersonic aircraft. MHI established its sole
national position as a supersonic fighter manufacturer
through the development of T-2CCV and the licensed proFig
duction of F-4EJ and F-15J. F-2 (Fig
Fig.. 1 ), which receiving
technical evolution flight tests by JASDF, is being developed based on U.S. GD (present Lockheed Martin)
F-16C by adding Japan’s own technologies such as composite wing, phased array radar, and digital fly-by-wire.
In the F-2 program, MHI has played the role of a total
system integrator. Defense demands to be emphasized
for the future include the creation of new products that
accommodate the information RMA (Revolution in Military Affairs) and the improvement of fighter technology.
More specifically, MHI intends to participate in total air
defense systems as a whole including fighters, pilotlessaircraft, and ground facilities, and to create new products. Additionally, from the perspective of improving
fighter technology, it is important to challenge new technology such as stealth technology, flight control
technology, and avionics integration technology aimed
at improving operational efficiency.
In particular, in order to ensure any future overall
defense system that performs joint operations, the effectiveness of such an element must be evaluated bysimulations, with a clearly defined vision. Any future
defense system cannot be defined without an adequate
information system. Accordingly, MHI has establisheda new IT laboratory in Tokyo in order to demonstrate
the concepts and the operational effectiveness of future
overall defense systems by simulations, and define MHI
proposals for future products. Using the IT laboratory,
MHI conducts activities to make customer-oriented proposals, taking into account the opinions and the ideas ofcustomers. Thus, MHI has taken the first step towards
the creation of such a large-scale integrated system, taking advantage of its ability to integrate many activities
for air, sea, land, and space. These activities are being
completed with the participation of all the related divisions in MHI Nagoya Aerospace Systems Works.
In the field of civil aircraft in Japan, YS-11 was firstdeveloped in the late 1950s after World War II. In addition to participating in the development of YS-11, MHI
also independently developed the multi-use double turboprop engine aircraft MU-2. This aircraft was capableof achieving short take-offs and landings, and flew at ahigh speed owing to its high wing loading, which was

F-2
F-16C

Fig. 1 F-2 Support Fighter
Shadowed area indicates F-16C.

superior to other competing aircraft at the time. A totalof 765 MU-2 were produced and sold. Fifteen years later,
MHI developed a compact business jet aircraft known
as MU-300, which achieved high speed performance andlow fuel consumption. This aircraft had a wing profilethat was designed to maintain the required lift and prevent sudden increases in resistance, even at high Mach
numbers. A total of 103 of MU-300 were produced. After
that, some civil aircraft were planned. However, they
were not produced because of the small size of the market and uncertainty of domestic demand. Due to suchcircumstances, MHI focused its efforts on designing andproducing specific portions of airframes developed byoverseas manufacturers under international joint development. Now, MHI is aiming to engage in the entire
assembly of aircraft through accumulated experience indeveloping and manufacturing specific portions. At
present, development of compact aircraft is being
planned in a public-private partnership. MHI also strove
to expand its share of the design and the production of
the structural parts for large civil aircraft, mainly twoaisle passenger cabin type aircraft (B767 and B777), in
cooperation with the Boeing Company. In the design andthe production of regional aircraft including component
installation, MHI also strove to improve design andmanufacturing capability with shortened delivery times,
and reduced costs through the adoption of concurrent
engineering techniques in cooperation with Bombardier
Inc. MHI also worked to strengthen its ability to acquire type certification based on structural analysis,
strength tests, and reliability analysis for component installation. MHI also manufactures parts for aircraft built
by Airbus Industrie, as a subcontractor. MHI must advance the development of technologies that strengthen
its ability to gain advantages in competition, if the company is to successfully engage in the entire assembly ofcivil aircraft in the future.
The helicopter business of MHI began from the knockdown production of S-55 helicopters developed by the
Sikorsky Aircraft Corporation for the Japan Coast Guard
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Table 1 Major aerospace products of MHI and history of development
Year

1960

1970
1965

Product[Aircraft]

1980

1990

1975

Civil aircraft
DC-10(developed through inter- Fuselage, cockpit
YS-11 (mass production)national joint cooperation)(development domesYS-11
tically in Japan)
MU-2(developed by MHI)

2000

1985
MD-11
747 flap

Tail cone
B767-200

2010

1995

-300
Aft fuselage, door

2005

2015

A-330/340 Cargo door
A-320 Shroud box

Airbus project

Aft fuselage,
High-efficiency next vehicle
tail cone,door
B-777-200
Sonic cruiser
B737-6,7,800 Inboard flap
-300

MU-300Transonic aircraft,composite design
Boeing Project

Compact aircraft (self-/jointly-developed)
Wing, center fuselage

GX

DASH8-

Fuselage, empennage
Bombardier projectCRJ-700 Aft fuselage
BO-100 Wing
Fixed wing aircraft for Japan Defense Agency(Aircraft built
under license)

F-86F

Acquisition of manufacturing technology

F-15J,DJ

F-4EJ

F-104J

Aircraft succeeding F-4(Developed aircraft)

Supersonic aircraft
technology

T-2
F-1

Digital fly-by-wire,
composites

F-2 support fighter

T-2CCV

Technology verification aircraft
System integration
Pilotless aircraft (super high-altitude Autonomous flight,
endurance type/tactical type, etc.) network technology

3

F-4EJ improved typeF-15 modification for modernization(Pilotless aircraft)
Helicopter

Future civil Helicopter

MH-2000(Helicopter forcivil use)

Mitsubishi Heavy Industries, Ltd.
Technical Review Vol.40 No.1 (Feb. 2003)(Helicopter for Japan
Defense Agency)

HSS-2/2B

S-92

International joint
development

SH-60K maritime
patrol helicopter

High-performance rotor

SH/UH-60J(A)Next generation Ship landing assist system
patrol helicopter
Advanced helicopter combat
direction system

Maritime patrol, Rescue, Utility

S-55/H-19

MH-53E

Transference to civil
enterprises, improvementof reliability, cost reduction,
large-scale tank manufacturing technology[[Space equipment]
RocketSeven rockets

Eight rockets

Nine rockets

Seven rockets

Robusttype

CAM

Space station
JEM

Needs for utilizing station
Operation by JEM
HTVSpace reentry
vehicle: License

SSPS (Space Solar Power System)
HOPE-X development: Joint development(including partial subcontract)

Enhancement of fundamental
technology for helicopters
Improvement of productcompetitiveness: Development for modification

Development of RLV prototype

Use of solar energy such as
SSPS
Weight reduction, maneuverability, and reentry technology: Domestic development

in 1953. After that, MHI produced helicopters continuously for Japan Defense Agency under a license contract
with the company. Significantly, MHI developed the SH60J, installing an automatic flight management system
originally developed by MHI into the U.S. Navy SH-60B.
Based on the success of the SH-60J, MHI expanded its
helicopter business in such a way that UH-60J(A), a derivative of the SH-60J was adopted by the Ground,
Maritime and Japan Air Self Defence Forces. Furthermore, MHI developed the shipboard maritime patrolFig
helicopter SH-60K (Fig
Fig.. 2 ). This helicopter has excellent hovering performance capability that is based on
the use of all composite main rotor blades, a ship landing assist system, and an advanced helicopter combat
direction system. A prototype of the SH-60K helicopter
was delivered to Japan Defense Agency last year. MHI
is striving to improve the maneuverability and the maintainability of these types of helicopters, as well as reduce
vibration with the aim of developing future types of helicopter for Japan Defense Agency. In addition, MHI has
developed a multi-purpose civil helicopter known as theMH2000, which has excellent safety features and low
noise emissions, and has already begun its delivery tocustomers. MHI is also participating in an international
cooperation development project that is aimed at developing a large S-92 helicopter through the teamwork ofsix countries. In this project, MHI has fully adopted thethree-dimensional CAD (CATIA) approach in the development of helicopters as well.
The aircraft engine business of MHI started with therepair of gas turbine engines for U.S. Air Force afterWorld War II. Then, MHI developed an original engine
TS-1 for an observation helicopter for Japan Ground Self
Defense Force. Using the accumulated technology applied in TS-1, MHI developed the MG5 engine for the
MH2000, and also developed an engine controller known
as the FADEC (Full-Authority Digital Electric Control)
installed in the MG5 engine. At present, technology for
mixed flow compressors is being accumulated as an extension of the technology used in centrifugal compressors,
because mixed flow compressors are suitable for making
medium-sized engines compact. In the area of large- andmedium-sized civil aircraft engines, MHI participates in
the production of the PW6000 engines of Pratt & Whitney(P&W) as a risk-sharing partner (7.5%), and is in chargeof a combustor module which is a core portion. MHI has
received orders for CF34-10 combustor cases from GE.
Based on these experiences, MHI strives to become apartner on equal terms and increase the number of customers it serves. MHI was certified as a Full Repair
Station for the PW4000 (94-inch type) by FAA (Federal
Aviation Administration) in 2002 so that MHI can extend its repair business. MHI is now actively striving tosecure more orders to repair airline engines such as the
PW4000.

Ship landing
assist system

Advanced helicopter
combat direction system

Advancedperformance rotor
Enlarged cabin

Advanced sonarFig.2 SH-60K shipboard maritime patrol helicopter
The figure shows an outline of the anti-submarine helicopter.

2.2 Trends of aerospace technology
There are two major needs for improving the performance of an aircraft as a system: improvements to theairframe itself and to the onboard systems.
In order to improve the function and performance of
the airframe itself, it is necessary to increase the transport efficiency and operational effectiveness of theairframe. In order to increase the transport efficiencyof the airframe, it is essential to increase the speed andreduce the weight of the airframe. One of the key technologies used to increase speed is the capability ofdesigning an optimum aerodynamic profile through theuse of CFD (Computational Fluid Dynamics). The key
to reducing weight is the ability to effectively design andanalyze composite structures. In order to improve operational effectiveness, it is necessary to improve thesafety and the reliability of the airframe, and extend
flight range. This can be done by promoting automation, decreasing pilot work load, and achieving
unmanned control, as well as by developing innovativemeans of improving maneuverability. Flight control technology based on the effective use of computers isnecessary to meet these needs. Such technologies are
essential for highly integrated autonomous systems, andalso serve as an information-connecting platform basedon IT. Such technology can be evaluated through theuse of flight simulations.
Improvements in the performance of onboard systems
are necessary in order to improve mission effectiveness.
Thus, it is necessary to focus on the development of cockpit-related systems that integrate internal and external
information, since they provide information, support decision-making, and facilitate the pilot’s action. These
requirements can be satisfied effectively by integrating
and improving the functions of avionics.
In order to succeed in the aircraft business, it is essential to develop, produce, and sell the best aircraft at
a low price and within a short time, based on a firm understanding of the needs of the customer. Hence, MHI
is moving ahead with the introduction of new technologies and improvements in production and support, with
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Management of stable design and quick production. Initial study is to be assigned to the best engineers.
. Planning drawings are to be prepared through team efforts.
(Downstream process information is to be reflected inplanning drawings, and thorough verification is to be donein advance.). The start is most important.
. Cooperation and mutual checking
by the design, production, andprocurement sections.
DBT activities
DesignPlanning
drawings
Basic design review meeting. Cost budget is prepared throughcooperation of the design, production,and procurement sections.

Three-dimensional
CATIA and Digital

Production. Prior assembly simulation by threedimensional numerical analysis ofaero-equipment.
. Common parts list is to be prepared for
all related sections.

Procurement

Quick production
Improvement of design quality/Reduction ofdevelopment time/Reduction of costs
Fig. 3 Concurrent engineering
The Figure presents an overview of the content of concurrent engineeringby cooperation of design, production, and procurement.

: Portion assigned to MHI. Portion assigned to MHI:
Aft fuselage, tail cone, passenger cabin doors
Development in very short time
Portion assigned to MHI

B777

G/A~Delivery of initial product(Months)
0
10
20
30
40
777
GX
DASH8
CRJ
BD100

. Portion assigned to MHI:
Wing, center fuselage, center wing

Global Express. Portion assigned to MHI:
Forward fuselage, center fuselage, aft fuselage,and empennage

Dash8-Q400
Fig. 4 Airframe portions assigned to MHI and development period
The Figure shows how development time has been shortened for each aircraft by concurrent engineering.

the aim of reducing the life cycle cost of an aircraft.
In addition, digital engineering is necessary in order toimprove the efficiency of the aircraft production system,
including both design and production. Actual digital engineering techniques, such as concurrent engineering andother methods described briefly below, have been actively
used and applied in the development of aircraft recently.
2.2.1 Design(1) Concurrent engineering
Concurrent engineering (C/E) and front-loading are
new methods that are used to enhance engineering
capability. In C/E, design and manufacturing data
are integrated in a consistent manner, so that material purchase, design, and production work proceedin parallel under well coordinated lateral cooperationin order to reduce dead times due to reworking and tocontribute to the reduction of development costs andperiods (see Figs. 3 and 4 ). The powerful motive force
behind C/E consists of three-dimensional design software as represented by CATIA. Such software
applications are not only capable of preparing threedimension drawings, but can also be used to analyze
stresses, design parts and assemblies, design threedimensional piping and wiring, as well as check formutual interference and clearances between parts ina product assembly. The use of CATIA makes it possible to reflect manufacturing requirements in adesign. For example, when designing and manufacturing a door, the accuracy of positioning for rivetingcan be improved by increasing the rigidity of the door
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Performancerequirements: Conventional flow
Design of
aerodynamics profileNO

NO: Present flow

Full FEM model of aircraft
Yes

Wind
tunnel tests

Yes Yes
Optimum
aerodynamics profile
Flow of aerodynamics design

Structural elements (examples)
Future method(Composites structure)

Strength

CFD

Conventional method(Metal property charts)

Design parameters
Design charts

Example of CFD analysis ofpressures around aircraft

Fig. 5 Aerodynamic design: CFD analysis
Flowchart for obtaining optimum aerodynamic profile and an
example of CFD analysis

Micro FEM modelFig. 6 Example of structural analysis of composites
The image shows an example of the structural analysis of composites
using a micro model.

at the design stage, so that the manufacturing needto increase the rate of automatic riveting can be reflected in the design. Future full automation of the
production of doors is intended to reduce manufacturing costs.
(2) Simulation
Simulation methods such as CFD (Computational
Fluid Dynamics), structural analysis, and flight analysis are positively used for analysis and evaluation in
all design phases. At present, these methods are also
actively used in the product-proposing phase represented by studies performed in the IT laboratories.
MHI intends to extend applications of simulation techniques throughout the overall life cycle of its products,
considering such techniques to be an essential technology of digital engineering.
Aerodynamic design: CFD
Formerly, in order to achieve high performance,wind tunnel tests were carried out in the design of aircraft using models based on drawings prepared at adesk. However, because wind tunnel tests consume
much time and money, the number of profiles that canbe evaluated is limited. Recently, the progress of computers has made it possible to obtain results based on
the numerical analysis of fluid dynamics that are essentially the same as the results obtained by windtunnel tests. In other words, CFD reduces the number of models and testing cases required for wind tunnel
tests, which contributes to reducing the cost and theperiod of designing. In addition, optimization programs, which not only analyze fluid dynamics for agiven profile but also create the best profile for a given
set of requirements, have been developed as design
tools. As a result, it has become possible to remarkFig.5
ably reduce design manpower (Fig.5
Fig.5).
Composites: Structural analysis
In the strength analysis of aircraft structures

mostly made of metals, the strength of each individual
structural member is evaluated by inputting the loadof the structural member derived from an FEM modelof the entire structure into calculation formulas anddesign charts backed up by experience. On the other
hand, in evaluating structures made of compositesthat have come to be used for primary structures recently, it has been clarified through the developmentof various products that there are limits to the simple
extension of the conventional evaluation procedures
used for metallic structures. It is not practical to obtain design charts only from elemental tests, because
a great many design variables are required compared
to metals. Consequently, it is necessary to establish
a special method to analyze the strength of composites. Since the fracture of composites is often caused
by internal damage such as delamination, the fracture mechanism has not yet been clarified precisely.
However, it has become clear that the fracture process can be clarified to a certain extent by FEM
analysis using microstructure models that can indicate differences between layers.
If the strength evaluation for general structures
is carried out using micro FEM models previously
verified in which design variables can be changed
parametrically, it becomes possible to obtain resultsthat are equivalent to conventional design charts. If
a design tool could be practically developed that makes
it possible to evaluate the strength of any composite
automatically simply by inputting design variables
and material properties, such a tool will become astrong support for designing the strength of composFig. 6
ite structures (Fig.
6).
Flight simulation
Recently, simulations have come to be widely usedin research and development, based on a model andsimulation concept, and are also being used for de-

.

.

.

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Fig. 7 Flight simulation
An example view of flight simulation is shown here.

Fig. 8 View of an integral panel produced
by FSW
The figure shows a picture of an integral panel
produced by friction stir welding.

termining the specifications of a system. The usual
aircraft simulator consists of a man-machine interface consisting of a cockpit, computer, and visual
simulation system. Inputting the design data of anaircraft newly developed into the computer, the simulator analyzes data concerning the flight performanceand characteristics obtained by simulated maneuvering, calculates loads on various maneuvering devices,and evaluates the human engineering of pilot interfaces. Due to recent advances in computer graphics
technology, real images can be shown so that a pilot
is able to evaluate various maneuvering factors andflight characteristics at high reality. As a result, computer graphics technology has become essential forFig
the development of aircraft (Fig
Fig.. 7 ).
(3)Integration and functional improvement of avionics
The first avionics systems consisted simply of anaggregation of individual devices. However, they were
integrated by various subsystems and connected bymultiple data buses. Data processing computers andman-machine interfaces have been integrated since
the latter half of the 1980s. At present, the conceptof the overall modularization of integrated devices andthe unification of specifications is emerging. In the
future, it is estimated that analog signal processing
hardware and sensors will also be integrated into
these avionics systems. As the function and performance of onboard avionics progress, displays in the
cockpit will become larger, more multi-functional, andoperate with many colors. Recently, new interfaces
such as displays with touch sensors, HMD (Helmet
Mounted Display), and voice information systems
have been added, and automated functions such as
an advising function for judgments based on an expert system have been introduced. MHI intends toimprove the information network function and develop
avionics and information systems that are capable ofaccommodating such an integrated service environment.
2.2.2 Manufacturing
In order to reduce the development and manufacturing costs of aircraft, CATIA should be used as a common
data media for all activities such as design, airframe

assembly and parts processing including design and production of jigs and tools. Parts manufacturing costs also
must be further reduced through die-less forming suchas peening forming, as well as fully automated hole-based
assembly systems and integrated parts.
(1) Processing of metallic parts
Assembly costs comprise a comparatively highshare of airframe production costs. Reducing thenumber of parts to be assembled is one of the mosteffective ways of reducing overall assembly costs. Accordingly, MHI has been accelerating the integrationof parts by integral machining from a thick plate, casting, super plastic forming, diffusion bonding, andwelding. The latest super high-speed machining is
expected to improve efficiency and reduce costs of integral machining. Casting is being applied even to
structural parts as a result of making progress in thesize, accuracy, and strength. SPF has been used for
fabricating the integrated inspection doors of Boeing
aircraft to save cost by remarkably reducing the number of parts compared to conventional rivet assembly.
MHI has been studying the application of Friction Stir
Welding (FSW), which was developed in the United
Kingdom, for aircraft. Fig
Fig.. 8 shows a prototype of an
integral structure of skin and stringers.
Another effective cost-reducing technology is dieless manufacturing. The wing skin plate of the
BD-100 business jet aircraft has been formed using a
shot-peen forming method, without any dies. At
present, MHI is also actively striving to develop aforming method that uses a flexible jig.
(2) Fabrication process of composites
Composite structures for aircraft have come to be
used as a method of reducing costs, because the number and weight of the parts can be greatly reduced
through co-cure process of composites. Co-cure process consists of first preform, individual laminatedstructural parts on each mold after heating slightly,
and then integrating the preformed structural partwith other preformed parts in a co-curing tool. The
integrated assembly in the tool is then cured in an
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Lay up anddebulk
CF/Resin
Prepreg

Preform inoven or autoclave(Half-cured for holding form)
Curing in autoclave

Skin
Bagging

Mold release andfinishing

Preliminary
formation
Setting forintegrated assembly

Reinforcement
material

Turning
upside down
Fig. 9 Concept of co-cure process
A schematic flow diagram is shown here of the co-cure process for composites.

Fig. 9autoclave, as it is (Fig.
9). In order to apply the cocure process to the large and complex wing of F-2,
both methods for preventing internal defects and formeasuring the pressure applied to complex portionsof the structure were developed. The processing condition of the autoclave was optimized by monitoring
its dielectric characteristics. As a result, it was possible to produce a co-cure wing box structure
consisting of skin, ribs, frames, and caps.
The interstage section of the H-IIA launch vehicle,
which is 4 m in diameter and 7 m in length, is also
manufactured by molding in an autoclave, resulting
in a 90% reduction in the number of parts. The prototype of the HOPE-X structure, with a 15 m longintegral composite structure of the wings and fuselage, has been manufactured using low-temperature
vacuum curing in an oven, instead of an autoclave
Fig(Fig
Fig.. 1010). A three-dimensional composite-forming
method in which the preformed material is made ofsolid form fabric composed by RTM (Resin Transfer
Molding) is expected as a future technology for imLow-temperature-cured
CFRP co-cure process + Mechanical joining

proving the performance of composites. In addition,
MHI is studying the development of new technologies
in order to reduce the costs of large composite structures. These include such methods as molding
composite by VaRTM (Vacuum Assisted Resin TransFig
fer Molding) (Fig
Fig.. 11 ), in which resin is impregnatedinto a woven fabric preform made of reinforced fiber
under a vacuum, as well as the combination of ultraviolet- or electron beam-curing and fiber placement
auto-lamination.

3. Progress of space technology
In the N rocket project started in line with the establishment of the National Space Development Agency ofJapan (NASDA), MHI was assigned the task of developing the N-rocket and its launch. In the development of
the LE-3 engine in Japan for the second stage, MHI developed a pipe-structured combustor constructed by noble
metal-blazing and a pipe-structured nozzle assembled
using electron beam welding and electric discharge machining, with technical guidance from Rocketdyne. These

Low- temperaturecured heat resistant
CFRP co-cure process
Vacuum bag
Medium for passing resin
Dry preforming

VacuumMold
Resin

Heating in ovenFig. 11 VaRTM forming
The VaRTM forming method uses vacuum impregnation
as a means of molding composites.

Low-temperature-cured
CFRP co-cure process + Secondary adhesion

SecondaryadhesionFig. 10 Original structure of the prototype of HOPE-X

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technologies have become the technical basis of current
liquid fuel engines. After that, MHI undertook the development of liquefied oxygen and liquefied hydrogen fuelengines, which were completed as the LE-5 second stageengine, after overcoming all difficulties. The H-I launchvehicle equipped with the LE-5 engine was launched in1986. Further improvements in performance were continued by Japanese domestic technology. In the firststage engine LE-7 for the H-II launch vehicle, MHI completed a two-stage combustion cycle system, which
demonstrated that MHI had attained the highest levelsof global rocket technology. MHI also strived to actively
simplify the structure and remarkably reducing the number of components, aiming at the commercialization ofrockets. However, the final launch of the H-II failed,
due to failure of the LE-7 engine caused by cavitation of
the hydrogen turbo pump. During the three years spent
determining the cause and implementing measures toeliminate the problems found, the global satellite launchmarket changed with an excessive production of rockets, making it more difficult to proceed withcommercialization. Nevertheless, MHI succeeded in theinaugural flight of the H-IIA launch vehicle in the summer of 2001, as a result of the overall review performed
in design, manufacture, and quality assurance. In the
future, providing for the transference of launch vehicles
to civil business, MHI intends to concentrate its fullpower on achieving success in the production and marketing of launch services. In addition, MHI is also
actively engaged in developing equipment for use in spaceother than rockets such as the Japanese Experimental
Module (JEM), Centrifuge Accommodation Module(CAM), H-II Transfer Vehicles (HTV), space solar powersystem, and reusable vehicles related to the international
space station, aiming at the future social demand in the
21st century.
3.1 Development of products(1) Launch vehicles (rockets)
The No. 1 through No.4 standard-type H-IIA
launch vehicles, each of which is capable of placing
a satellite weighing about two tons into a geostationary orbit, achieved cost reductions andimprovements in reliability through the adoption ofvarious new technologies, towards the privatizationof the rocket business. Various improvements havebeen applied to the H-IIA in order to simplify theconstruction and launching work involved. These
range from improving the first and second stage engines through modifying even the ground facilities
as well as construction of the fuselage, based on thetechnologies and experience gained through work on
the H-II. It is no exaggeration to say that almost allcomponents of the system have been improved. As aresult, the cost of the H-IIA has been reduced to halfthat of the H-II, and its capability has now achieved
a level that is fully competitive with other commerTable 2 ). In thecial launch vehicles in the world (Tablefuture, MHI intends to accelerate improvements oflaunch systems and development of enhanced typesof launch vehicle, together with measures for thetransference of the rocket business to civil enterprises, because launching capacity must be increased
in order to participate effectively in the global rocketmarket.

Table 2 Launch vehicles (rockets) developed in Japan and overseas
60 m

40 m

20 m

Name of rocket

Arian IV

Nationality

Arian V

EuropeOrganization

Atlas

Delta III

Chang Zheng

Proton(Long March)-3

Russia

U.S.

Japan

China

MDC

USAF

IPPI

Total weight

(t)

480.0

725

321.8

187

770.0

260

288.0

240.0

Launch to low orbit

(t)

9.6

18

8.3

8.6

21

10.0

10.0

8.5

Launch to geostationary orbit (t)

4.5

6.8

3.8

3.8

4.9

4.0

4.1

2.6

90 to 108108 to 126

108 to 118

170 to 190

75 to 85

54 to 66

ESA

Cost of launching
120 to 150 180 to 216(one hundred million yen)

CNSA

NASDA

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Payload fairing
Change of the number of panel segments and bonding method
Simplification of manufacturing process..
Avionics.. Integration of boxes and use of highly integrated electronic devicesof data bus system. Introduction
Automatization of checkout and enhancement of self-check function
Second stage.. Separation of tankof LE-5B engine (by improving LE-5A).. UseSimplification of propulsion system. Use of electric motor-driven actuator (propulsion control system)
Rearrangement of onboard electronic components

First stage
Simplification of structural system fabricating processes
Change of core, SRB-A and launch pad joining method
Simplification of propulsion system
Use of LE-7A engine (by improving LE-7)
Change of component installation and simplification of system
Increased use of casting and machining procedures

H-II

.

..
..
..
Solid fuel rocket motor (SRB-A).. Use of integral CFRP motor caseof nozzle size
. Reduction
Use of electric motor-driven gimbal actuator

Fig.12 H-IIA improvement
The H-IIA launch vehicle was developed from the H-II with the following improvements.

Fig. 12Outline of H-IIA launch vehicle (Fig.
12)
The H-IIA launch vehicle is equipped with a firststage LE-7A engine and a second stage LE-5B engine. In order to simplify and reduce the number ofcomponents used, the first oxygen tank of the propulsion system is pressurized using oxygen that ispartially vaporized from liquefied oxygen, instead of
cryogenic helium. Function testing work on the gimbal system has been simplified by the blow down
hydraulic system in the first stage, and using an electric motor instead of a hydraulic system in the second
stage. In the construction of the rocket, the integraltank with a common vacuum heat-insulated bulk
head in the second stage of the H-II has been changed
to individual tanks joined by a truss structure in the
H-IIA. As a result, the tanks have become easier toassemble, and control of temperature and pressure(pressure difference between the tanks) has been
simplified when propellant is charged at a cryogenic
temperature. The weight of the interstage sectionthat joins the first and second stages has been reduced by changing the material used from aluminumalloy to carbon fiber composites (CFRP). A data bus
system is used in the electronic control avionics forcontrolling the rocket to simplify the connection between the onboard equipment and the ground facility
when launching the rocket. In addition, the data
bus system makes self-diagnostics of devices easier.
As a result, it has been possible to raise reliabilityof the onboard equipment through self-diagnosis. On
the other hand, the most difficult task in the development of N-1 through H-IIA launch vehicles was
the development of the engines. However, these dif-

H-IIA
(Courtesy of NASDA)

ficulties were overcome by the development andadoption of the two-stage combustion cycle system
for the first stage LE-7A engine of the H-IIA system.
The entire amount of liquefied hydrogen and a portion of the liquefied oxygen system are fed into thepreliminary combustor called a pre-burner in orderto generate a high-pressure combustion gas thatdrives both the liquefied oxygen and hydrogen turbo
pumps. After driving both turbo pumps, the exhaustgas is then sent to the main combustor to be burned
again and output as part of the thrust power. Dividing the combustion process into two distinct stages
in this way has made it possible for the LE-7A engine to achieve a high level of efficiency. However,development of the engine has led to the need to continually overcome extremely severe conditions.
These include the liquefied hydrogen, which is discharged at a temperature of -253 o C and a pressureof 27 MPa from the turbo pump, coming into directcontact with the main combustor with a temperature of about 3 300 oC and a pressure of 13 MPa, as
well as the generation of extreme levels of mechanical and acoustic vibration at the time of combustion.
Despite such conditions, however, each of these various difficulties were overcome one by one as theengine was completed. At present, MHI intends toaccelerate its effort to commercialize H-IIA launchvehicle, e.g. further improvement of performance of
the LE-7A engine through use of a long nozzle skirt
for complete regeneration.
(2) Development of Japanese Experimental Module(JEM)
Tests on the Japanese Experimental Module
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(Courtesy of NASDA)(Courtesy of NASDA)

Japanese Experimental Module(JEM) "Kibo"
Fig. 13 Development of international space station
Overall view of the international space station

International space station

Courtesy of ISAS

Fig.14 Concept of reusable launch vehicle
An external view is shown here of an RLV (Reusable
Launch Vehicle).

Table 3 Outline of reusable transportation vehicle for space
Requirements for maneuvering system
Payload capacity:
Probability of losing rocket body:
Operating period during flight:
Number of operating crew during flight:

Main specifications of rocket body
LEO 3 ton
1/400
7 days
100 man- day

Overall length: 29.0m
Gross weight: 98.0ton
Propellant:
Liquefied oxygen/liquefied hydrogen

LEO: Low Earth Orbit(Fig
Fig.. 1313) for the international space station have been
Fig
completed with respect to the combination of the payload and the ground system at the Tsukuba Space
Center of NASDA as the final test in Japan. The
module will be transported to the Kennedy Space
Center of NASA in 2003. It will be launched after it isprepared for launching by NASA at the launching site.
In addition, MHI is developing CAM (Centrifuge Accommodation Modules), a centrifuge facility (forresearch in life science) to study the effects of the gravity environment on life, and an H-II Transfer Vehicle(HTV), one of the transporting vehicles to be used asa supplier vehicle for the space station.
(3) Reusable launch vehicles
MHI is studying the feasibility of utilizing reusable launch vehicles as a means of space transport,
instead of conventional expendable vehicles. One of
the aims of this study is to realize significant extensions in future space activity through substantial cost
reductions, while at the same time achieving levelsof safety and reliability that are equivalent to thoseof conventional aircraft.
Several concepts are being examined for reusable
launch vehicles; vertical launching and horizontal
landing type such as space shuttles, horizontal takeoff and landing type such as general aircraft, andvertical launching and landing type. Fig
Fig.. 14 shows
an example of a horizontal takeoff and landing type,which is the first step toward the development of future manned space vehicles and fully reusable space
e 3 , aim
vehicles. These studies, summarized in Tabl
able
at establishing design procedures for achieving highreliability and the acquisition of basic technologies

Solar cell panel
Phased array typetransmission
antenna

Microwaves

Receiving facilityon the ground

Illustration of system in orbit

Fig. 15 Space solar power system (SSPS)

for developing robust engines and lightweight structures, as well as service. In order to further reduce
costs and improve reliability, MHI is studying the feasibility of reusable vehicles, based on the use of basic
technologies such as composite structures, heat resistant material, and guidance and control
technologies fostered through the development of thereentry vehicle, and rocket-propelling technology,
cryogenic propellant management technology, andlaunch and service technology fostered through thedevelopment of the H series of rockets. MHI considers these efforts to be a program that will build thebasis for future space transportation systems following vehicles currently in use.
(4) Space Solar Power System
The space solar power system (SSPS) is a systemthat sends electric power generated by solar power
generation to the ground via microwaves that are received by a microwave-receiving facility on the ground,
and which are then converted into electric power
Fig(Fig
Fig.. 15
15). The generation of solar power in space willachieve a generating efficiency that is ten times higher
than that possible on the ground, because it is not
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Technical Review Vol.40 No.1 (Feb. 2003)11

affected by day and night, or even by weather. It is aclean source of energy that does not consume any fossil fuels, thereby making an ideal means of coping with
global warming. In order to send the space generated electric power to Japan, it is necessary to build
a power station in space in a geostationary orbit (orbital altitude: 36 000 km) close to Japan. In order torealize the potential of power generation in space andpower transmission facilities, a wide range of technologies such as power transmission control using
microwaves, power receiving facilities on the ground,and low-cost transport of materials from the groundto space are required. Accordingly, MHI is currently
carrying out research and development into each ofthese areas. Fig. 15 shows an illustration of a large
scale SSPS in orbit. The capacity of the space power
station in this case is several hundred thousands toone million KW, while the diameter of the power transmission antenna is several hundreds to one thousand
meters, and the diameter of the space solar powerreceiving facility on the ground is several kilometers.
MHI is planning to demonstrate a solar power generation in space with a technical verification satellite
and a pilot plant for the verification study of thesetechnologies, with the aim of realizing a practical solar power station. In order to establish a full-scale
system, it is essential to develop effective space trans-

portation systems. Hence, further activities in thedevelopment and the implementation of space transportation systems, MHI’s strength, are expected to
expand even more in the future.

4. Conclusion
The aerospace business is a fundamental business,
which supports “Transportation systems” and “Defense
systems” fields that MHI deems even more important in
the future. MHI intends to strive to advance and expand
its own technologies for designing and manufacturing
aircraft and rockets, to support this business activity.
The authors would like to extend their sincere appreciation for all the guidance and encouragement being offered
now and in the future to MHI in these endeavors.

AEROSPACE HEADQUARTERS
Managing Director,
General Manager,
Aerospace Headquarters

Junichi Maezawa

Minoru Kobayashi

Mitsubishi Heavy Industries, Ltd.
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