<Composite Cryogenic Propellant Tank/Material Characteristic Test>
Material test data that is imperative for tank development has been acquired. The structure of the tanks is aluminum liner wrapped in Carbon Fiber Reinforced Plastic (CFRP). CFRP, that strengthens the tank structure, is adhered to the aluminum liner containers that hold the propellant. The purpose of the test this time is to understand more precisely the material characteristics in a cryogenic environment, and to measure the strength and toughness of adhesive and CFRP.
(Photo A: Shear stress is applied to a test item made of two pieces of CFRP attached together.)

<LNG Igniter/Unit Test>
An LNG igniter was tested at the Kakuda Space Propulsion Center (KSPC) for design verification. We acquired meaningful data including some unexpected phenomena that had not been projected through analysis before the test, and we will incorporate the test results in the design and test the igniter further.
(Photo B: An igniter unit test. Sudden changes in temperature and pressure at the time of ignition were measured at a high sampling rate.)

<Subscale LNG Engine/Firing Test>
The firing test of the one-fifth subscaled engine was also held at the KSPC. Although we were able to acquire some useful technical data, we had no choice but to give up the test midway through it as some parts including the injector of the engine were broken at the time of engine cutoff.
By closely studying the acquired data, we currently estimate that the cause of the anomaly was “abnormal combustion in the injector due to backward flow of combustion gas from the combustion chamber to the injector.” We will further examine the data and incorporate the results in a test item and facilities to be ready for the next test.
(Photo C: The firing test by the one-fifth subscale model with about 50 mm diameter throat)

A launch vehicle with LNG as its propellant is expected to be a high performance vehicle with low costs, but nobody in the world has successfully implemented its practical use. Therefore, it is very important to acquire basic data and steadily accumulate enabling technologies.

In Japanese Fiscal Year (JFY) 2003, JAXA carried out the following studies and tests.

(1) Together with the Tokyo Metropolitan Institute of Technology we studied LNG/oxygen ignition characteristics. The study aimed to acquire basic data on ignition, and we performed 475 ignition tests in total under different conditions. We were able to acquire ignition characteristics data on premixed methane and oxygen gas under pressure lower than 0.2. This had previously been an unexplored area for which we could not find data, even in overseas academic documents. The data will be useful for designing an igniter. We continue to acquire the necessary data for designing this in JFY 2004 by making the combustion condition visible inside the actual igniter.

(2) We carried out tests on a full-scale composite cryogenic propellant tank for liquid oxygen in ambient and cryogenic temperatures. Structural data, such as distortion and displacement under changing temperature and pressure conditions was acquired. In JFY 2004, we continue to study the technical challenges found in the data and incorporate our findings into the tank design.

(3) We performed a simulation test on in-flight propellant conditions (including surface tension and viscosity) under a space gravity environment. We acquired very good test results on liquid movement that was compatible with the analysis results (that were performed by an analysis method co-developed by JAXA and the University of Tokyo http://park.itc.u-tokyo.ac.jp/jetlab/themes/twophase/twophase.html.) We will further analyze propellant behavior under in-flight conditions

(4) We started experimental model production and evaluation tests for an electric actuator system that will control engine swiveling, as we have already completed the design. The system is composed of an electric actuator, a controller for the actuator, and batteries for power. The technical data acquisition test for design evaluation was recently completed, and critical design issues are currently being reviewed. In JFY 2004, we will perform a vibration test and temperature test for verifying if it is strong enough in the harsh environment of launch vehicle engine operations, and will move onto the stage of fixing the final flight model design.

Photos: Experiment equipment
Ignition through a view window

In Japanese Fiscal Year (JFY) 2003, a full-scaled model of an LNG (liquid natural gas) composite cryogenic tank was tested both in normal temperature and cryogenic condition. The objective of the tests was to acquire data concerning structure, such as distortion and displacement data, under the environment of changing temperature and pressure to incorporate them into the design of the flight model. The objective was mostly fulfilled as planned.
In addition, a full-scaled model of an LOX (liquid oxygen) composite cryogenic tank that is scheduled to be tested in JFY 2004, was also manufactured.
Furthermore, a structural test was carried out using a full-scaled model of the front and rear panels that were for binding four composite cryogenic tanks like clusters, and successful test data were acquired.

Photo: Test model of the front panel for a stiffness test

LNG engine BFT (Battleship Firing Test)
In JFY 2003, a battleship firing test (BFT) for the LNG (liquid natural gas) propulsion system was performed. A BFT was to verify design appropriateness, such as control characteristics of a launch vehicle propulsion system, by a firing test of a stronger tank than a flight model, while a flight model of a propulsion system was being simulated. The test was called a "battleship firing" test because a tank whose wall was thicker than a flight model was used.
The test was successfully carried out including firing of 353 seconds (or MDM, mission duty cycle) required for actual flight operation, and excellent data were acquired.

Photo: A test piece of the MDC firing demonstration

Anambient temperature strength and rigidity test on the cryogenic composite tank for liquefied natural gas (LNG) was conducted in May, fiscal year 2002. The main purpose of this test was to obtain rigidity data on a full-scale model at normal temperatures in order to reflect it in the actual tank design. The test was conducted as planned. A low temperature strength and rigidity test on the cryogenic composite tank for LNG and ambient and low temperature strength and rigidity tests on the cryogenic composite tank for liquid oxygen (LOX) are also scheduled in 2002 (FY.)

Photo: A test piece of the cryogenic composite tank for LNG

The mission duty cycle (MDC: 353[sec]) firing demonstration on the LNG engine was conducted in 2001 fiscal year to acquire the performance data during the assumed time period of actual flight and to also confirm the durability of this component. Both the performance data and the durability were preferable. The Battleship Firing Tests (BFT) on the LNG engine are scheduled for 2002 (FY).

Photo: A test piece of the MDC firing demonstration