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Contribution to Japan's Flagship Launch Vehicle – part 2-Successful Launch of the first Epsilon Launch Vehicle-

TATSURU TOKUNAGA*1 NOBUHIKO KOHARA*2

KATSUYA HAKOH*3

TSUTOMU TAKAI*4

KYOICHI UI*5

TETSUYA ONO*6

On September 14, 2013, the first Epsilon Launch Vehicle was launched from (Independent
Administrative Institution) Japan Aerospace Exploration Agency (JAXA) Uchinoura Space Center,and succeeded in properly injecting a satellite into orbit. In Epsilon Launch Vehicle development,
we participate in the development/manufacture of the second-stage reaction control system(RCS)
and modification maintenance of the launcher for the Epsilon launch system. The
development/maintenance details and launch results are introduced in this report.

|1. Introduction
JAXA started development of the Epsilon Launch Vehicle in 2010, going through the stagesof vehicle development, manufacturing, and maintenance of launch-related facilities, until the first
Epsilon Launch Vehicle was launched from Uchinoura Space Center in 2013. We contributed tothe successful launch of the first Epsilon Launch Vehicle through development of the second-stage
reaction control system, which was equipped onto the launch vehicle, and modification
maintenance of the launcher. Details of the development/maintenance and the launch results are
introduced here.

|2. Approach to Epsilon Launch Vehicle Development
2.1

GeneralThe Epsilon Launch Vehicle is the three-staged solid rocket developed by JAXA since 2010,
and is the successor to the M-V launch vehicle technology, which completed operations in 2006,
and develops to organize technical application/commonality of the H-IIA launch vehicle.
In addition, the launch complex for the Epsilon Launch Vehicle takes maximized using of the
M-V equipments in the JAXA Uchinoura Space Center ; maintenance is undertaken by modifying
an existing M series launcher and rocket assembly building.
Of these, we participate in the development of the second-stage reaction contorol system(RCS) of the Epsilon Launch Vehicle, and modification maintenance of the M series launcher inthe launch site.
As shown in Figure 1, the first Epsilon Launch Vehicle consists of solid motors, from thefirst stage through to the third stage, and a compact liquid propulsion system (Post Boost Stage:
PBS). Two reaction control systems (RCS), which we were in charge of, are installed in the bottom
part of the second-stage motor (Figure 2). In addition, assembly whole stages of launch vehicle,
transportation to launch pad and launching are done by using the M series launcher including alauncher and a mobile service tower which we were in charge of. The overview of the M series
launcher in the Mu center of the Uchinoura Space Center is shown in Figure 3.
*1

Chief Staff Manager, Space Systems Engineering Department, Space Systems Division, Integrated Defense & Space Systems*2

Space Technology Application Department, Space Systems Division, Integrated Defense & Space Systems*3

Space Systems Engineering Department, Space Systems Division, Integrated Defense & Space Systems*4

Maritime & Space Systems Department, Integrated Defense & Space Systems*5

Ph.D., Associate Senior Engineer, Epsilon Rocket Project Team, Japan Aerospace Exploration Agency*6

Engineer, Epsilon Rocket Project Team, Japan Aerospace Exploration Agency

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Figure 2 Second-Stage Reaction Control
System (RCS)

Figure 1 Structure of Epsilon Launch Vehicle

2.2
(1)

Figure 3 Overview of M series launcher

Development of Second-Stage Reaction Control System (RCS)
Outline of Second-Stage RCS
The second-stage RCS is installed on the rear ring of the second-stage solid motor; it has
an attitude control system used to control the attitude in the second-stage flight phase. The RCS
has a module configuration that consists of one fuel tank, six (4 for the first launch vehicle)
23N class monopropellant thrusters, pipings, valves, and support structure, and each of them isinstalled on a "+" and "-" side of the Y-axis (a radial direction) of the second stage. The basic
design of the RCS is shown in Table 1, and its schematics is shown in Figure 4.
Table 1 Basic design of the second-stage RCS
Type
Propellant supply system
Fuel tank configuration
Usable fuelThruster structure
Mass

Specification
Hydrazine monopropellant
Blowdown typeAll metal spherical tank
Hydrazine (N2H4)
Six 23N class thrusters(4 for the first launch vehicle)
About 32 kg

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Figure 4 Schematic diagram of the second-stage RCS(2)Development History
We have developed many space craft propulsion systems including the third-stage
attitude control system (side jet: SJ) of the M-V launch vehicle. We develop and manufacture
the second-stage RCS of the Epsilon Launch Vehicle by using accumulated experience and thefollowing development designs,(a) Provide an interchangeability in the fuselage and between continuation unit to optimize
serviceability as a built-in unit(b) Secure reliability and reduce the cost by using existing components with a heritage(c) And introduce domestic products preferentially for equipment that tends to be a bottleneckin procurement(3) Development Issues and Results
For SJ of the M-V launch vehicle that had been developed, delivery time and cost were
the issues through the use of imported propellant valves. Therefore, for the second-stage RCS,
it was decided to use domestic propellant valves of a satellite with a design change (change tosingle seal and interface) for the launch vehicle. As for a new adoption of the domestic
propellant valve, an environment test in conditions which utilized a jet motor manufactured by
us was executed and confirmed to the design specifications.
(4) Manufacturing Result
As for the manufacture of the flight model, performance/function were evaluated forcomponent level and subsystem level, and the model was carried into the Uchinoura Space
Center. After being moved into the launch site, a pressure test and function test was executed;
the model was inspected its conformity and it was then delivered to JAXA.

2.3
(1)

Maintenance of Launcher
Launcher Outline
The M series launcher used for vehicle assembly and launch of the Epsilon Launch
Vehicle took full advantage of the M-3S launcher manufactured (in our then Kobe Shipyard) in
1982, which was modified/maintained in 1995 for the M-V launch vehicle. It mainly consists ofa service tower, launcher, frame duct, air conditioning system and umbilical system; thepreliminary design of the modification was started in July 2011, on-site construction wasstarted in November 2012, and was delivered to JAXA in May 2013.

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Service Tower
The service tower was located at the rotating terminal of launcher; it accommodated thelauncher, had functions available to assemble the first stage and fairing vertically one by one
and to checkout health status of the vehicle on the launcher; it was modified as follows(Figure 5):(a) Newly equipped with an overhead crane that could lift and assemble the first stage andfairing to the vehicle support platform(b) Reinforced service tower structure accompanied by increased capability of overhead crane(c) Newly equipped operation floors (third, sixth, seventh and eighth) to correspond with thevehicle access windows on the Epsilon Launch Vehicle, which are used to safely and easily
checkout operation
The lifting capabilities of the overhead travelling crane were reinforced to 100 tons fromthe preexisting 50 tons, in response to the lifting mass increase in comparison with the previous
M-V launch vehicle, and the hoisting drive control realizes a lowering rate of 0.83mm/sec
during vehicle assembly by adopting the vector control system that used an inverter to generatesufficient torque, even at low speed, and a rate analyzer. Through these, the vehicle assembly
operation could achieve to prevent a shock to the first stage and fairing without using a special
tool of the precise vertical control (ex. Hydra-Set), and simplified launch operation is achieved.
Finally, at the on-site verification test before the delivery, a dummy rocket was used tosimulate the geometry of the Epsilon launch vehicle, the mass, and center of gravity; the lift up
and setting of the first stage and fairing were confirmed to be able to operate as we expected.

Figure 5 Overview of service tower(3)

Launcher
The launcher is a structure independent from the service tower, which has the function ofrotating the launch vehicle while it is moving to the launch pad from the service tower, andconsists of a dolly, rocket support platform, and boom (umbilical mast). (Figure 6)
The rocket support platform to directly install the launch vehicle supporting the entire
load of the Epsilon Launch Vehicle, and installed to the preexisting dolly as steel framework
which has sufficient strength to reduce a drift area at the lift off.
The existing link structure was modified, because the boom, which had the air
conditioning system between the ground facility and the launch vehicle and the function of
power/signal interface, stood vertically before launch but it was necessary to move to a
non-interfering position where beyond the vehicle drift area (opposite direction of the launchvehicle) after launch.

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Figure 6 Overview of launcher/frame duct （図中も frame duct へ修正済み）

The launcher, including the launch vehicle, was modeled for structural analysis, and thestrength/rigidity and impact of the launch vehicle were examined by the following analysis(Figure 7). In addition, a structural analysis model was simulated based on the results of themodal survey after modification of the launcher(a) Static analysis ... Evaluate rigidity and strength of the launcher(b) Natural frequency analysis ... Evaluate natural frequency of each mode(c) Earthquake analysis ... Evaluate strength of components, displacement, and response
acceleration in case of an earthquake(d) Wind resistant characteristics ...
① Evaluate strength of components and displacement by static response analysis with asteady wind
② Evaluate resonance wind velocity by the Karman vortex

Figure 7

Rocket Suport Platform stress contour diagram

An example of FEM analysis results for rocket support platform is shown.

The earthquake analysis results indicated that the vehicle overturned at the maximum
presumed seismic intensity in some cases. Therefore a vehicle overturning prevention unit was
installed on the upper part of the launch vehicle support stand.
The vehicle overturning prevention unit is a structure securing the launch vehicle’s
bottom end, and is left open just before launch. The launcher and the vehicle overturning
prevention unit was modified for a remote control system so that it had manipulability while
being remote from the launch control center if the launch vehicle was sent back to the service
tower during an emergency such as a lightning detect, and the remote control operation monitor

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station (touch panel) was placed in the launch control center.
Finally, at the on-site verification test before the delivery, the dummy rocket thatsimulated the geometry, mass, and center of gravity of the Epsilon launch vehicle was loaded
onto the launcher, and confirmed that the series of turning and returning operations was able tooperate on schedule.
(4) Frame duct
The frame duct, which deflects and drains the combustion gas at the lift off, is installed
for the purpose of reducing the impact to the radio waves link by the smoke and to the satellite
and launch vehicle equipped instruments by the acoustic environment, and it consists of alauncher side frame duct and ground side one. The frame duct is designed to endure plumepressure (temperature) and over pressure from the launch vehicle; the launcher side frame duct
has a structure with an installed steel plate squared to surround the inside of the vehicle support
platform frame and rotate with launcher to arrange at launch pad. The ground side frame duct isarranged at the launch pad; it is a reinforced concrete structure in the form of a tunnel toprevent acoustic diffusion based on acoustic analysis and acoustic test results from a scalemodel by JAXA. The launcher side frame duct, which rotates with the launcher, overlaps theground side frame duct in the launch pad, and forms an integrated flue configuration from thebottom of the vehicle to the exhaust slot (Figure 6 and Figure 8).

Figure 8 Overview of frame duct
Overview photo of frame duct is shown.

Figure 9 Overview of No. 2 movable air
conditioning vehicle for fairing
Overview of No. 2 movable air conditioning vehicle
for fairing is shown.

(5)

Air Conditioning System
There are two air conditioning systems to maintain the launch opereation andsatellite/instrument environment. One is for the service tower and the other is for the satellite in
the nose fairing and the instrument which are installed in the first stage engine area.
For the service tower air conditioning facility, the preexisting facility could be operated
and we decided it could be reused after maintenance. The source of the air conditioning supply
for the first stage and nose fairing air conditioning system could not be adapted to the vehicle
interface of the existing air conditioning unit of the vehicle, and it was decided to reuse andoperate the No.2 movable air conditioning vehicle, which was assigned from the Tanegashima
Space Center (Figure 9).
When the fairing was transported between the rocket assembly building and service
tower, the No.2 movable air conditioning vehicle ran by itself and maintain satellite
environment by sending conditioned air. After the fairing was installed, the fairing air
conditioning transfer vehicle No. 2 was arranged and fixed at the west side of the service tower;
the system passed through the first stage and the nose fairing duct and umbilical duct,
constructed along with the boom, which ran through the center of the rotating dolly; the facility
is to maintain the environment by sending conditioned air to the first stage and fairing until thelift off.
In addition, the first stage/nose fairing air conditioning system was modified to enableremote checking of supply humidity/temperature and flow rate and changing the setting fromthe monitor station (touch panel) placed in the launch control center at a distance from thelaunch pad.

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Before the delivery, we confirmed that the function of the systems are according to its
design by sending conditioned air under the operational launch conditions.
(6) Umbilical System
The umbilical system is the equipment to connect electricity and fluid between thevehicle and the facility during launch operation, and to disconnect and evacuate according tovehicle ascent after lift off. The Epsilon Launch Vehicle differs from the conventional existing
M-V launch vehicle which uses inclined launch system, and adopts a vertical launch system thesame as the H-IIA/B launch vehicle. Therefore, the umbilical system for the Epsilon Launch
Vehicle takes full advantage of the FLY-AWAY system using in the H-IIA/B launch vehicle;
development was realized at low cost and over a short term. The outline of the FLY-AWAY
system is shown in Figure 10. The umbilical system for the Epsilon Launch Vehicle wasdeveloped following technical challenges owing to the restrictions of the preexisting facility.
(a) Because the evacuation distance after the umbilical system had separated from the vehicle
was short, the acceptable bounce range was small after evacuation.
(b) When the umbilical system was evacuated, the capturable range was limited.
Regarding this matter, we newly developed a compulsion retracting system and verified
system operation for defective behavior, evacuated the location and bounce area by averification test using a dummy rocket, which went according to plan (Figure 11).

Figure 10

Outline of umbilical system for FLY-AWAY system

Figure 11

Condition of confirmation test for umbilical system separation

Umbilical system are separated from launch vehicle and evacuated in direction of facilities
accompanied with vehicle ascent|3. First Vehicle Launch Result
The first Epsilon Launch Vehicle was launched from JAXA Uchinoura Space Center at
14:00 on September 14, 2013, and it successfully injected a satellite into its predetermined orbit.
On the occasion of the launch, the electric power and air conditioning was supplied to thevehicle and vehicle support until lift-off and during the rotating move to the launch pad; attitudecontrol to attempt stability of the vehicle attitude was correctly carried out by the RCS at thesecond-flight phase after launch.

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3.1

The Second-Stage Reaction Control System (RCS)

Through the flight data of the first Epsilon Launch Vehicle, the operating results of thesecond-stage RCS was followed, and it could be evaluated that the operation worked correctly.
(a) The transition of the pressure and temperature range was predetermined before launch until
the second and third stage separation after the end of the operation.
(b) By pressure transition and operating condition of the thruster, the propellant valve wasoperated normally, and the attitude control in the second-flight phase of the launch vehicle
was normal.

3.2

Launcher Operation

In operation of the launcher, procedures for the combination of the first stage /nose fairing
facility operation (fairing transport) and the launch operation (Y-5 to Y+1) were maintained, andeach two teams for launcher and umbilical executed operation respectively. The launcher team wasin charge of operations related to the service tower, launcher, the first stage/nose fairing air
conditioning and electric facility, and the umbilical team was in charge of operations related to thefirst stage system and umbilical facility of the fairing system.
Launch operation contents were according to Figure 12; since twice of the postponement andthe rehearses execution, Y-0 operation on the launch day were attended with familiarize conditions.

Figure 12

Operational flowchart

The figure shows the operational flowchart from first-stage installation throughinspection after launch

At the launch day(Y-0), launcher turning and preparation, boom evacuation, vehicle
overturning prevention unit release, and umbilical system carrier evacuation at the launch was
satisfactory, and we contributed to the successful launch of the first Epsilon Launch Vehicle withthe operation time according to plan proceeding without problems (Figure 13). In addition, aroundthe launch pad, an acoustic measurement is performed by JAXA; there was no problematic
influence about acoustic environment on the interface of the loaded satellite at the advance
predicted level, and the constructed frame duct was confirmed to function well (Figure 14).
Each piece of equipment of the launcher was inspected after blastsoff, and the facility waschecked regarding its damage status. There was some damage that was beyond the level ofprediction at the design, but it was considered in detail for the next launch to repair, remodify, andimprove the design base on the first launch.
In addition, extracted improvement/refinement of reliability, operability, safety, andserviceability of instruments through the operation will be reflected in the next launch, and we areplanning to work so the customer has increased satisfaction.

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Figure 13

Figure of launcher rotating situation

Figure 14

Result of external acoustic measurement at the first launch

The picture shows the process of rotating the launcher at Y-0

The chart shows measurement results (envelope value) against external acoustic control level.

|4. Conclusion
Development of the second-stage RCS in the Epsilon Launch Vehicle and maintenancecontents of the launcher were introduced. For the first launch vehicle operation, there were noserious problems in either of the above, and we were able to contribute to the successful launch inspite of the first Epsilon Launch Vehicle. The reflection and improvement subject provided throughthe operation was discussed for the next launch, and we continuously support the innovation of thespace transportation system of our country including Epsilon Launch Vehicle.