At 13:40 on September 22, Jiangsu Deep Blue Aerospace Co., Ltd. carried out the first high-altitude vertical recovery flight test of Nebula-1 at the Deep Blue Aerospace Ejin Banner Spaceport in Inner Mongolia China, People’s Republic of China … The recyclable and reusable first-stage rocket body had an abnormality during the final landing phase of the flight test, and the test mission was not completely successful. According to the “Nebula-1 First High-altitude Vertical Recovery Flight Test Test Outline”, there are a total of 11 major test verification tasks. In this flight test, 10 of them were successfully completed and 1 was not completed.
China’s first high-altitude recovery flight test of a launch vehicle that can enter orbit…. At 13:00 on September 22, Jiangsu Deep Blue Aerospace Co., Ltd. carried out the first high-altitude vertical recovery flight test of Nebula-1 at the “Deep Blue Aerospace Ejin Banner Spaceport” in Inner Mongolia. An abnormality occurred in the recyclable and reusable first-stage rocket body during the final landing phase of the flight test, and the test mission was not completely successful. The core mission objectives of this test are to verify the correctness and coordination of the operation of various systems in the vertical recovery phase after Nebula-1 enters orbit, especially to verify the multi-machine to single-machine variable power operating conditions for the first time in flight, and to accumulate key data for subsequent 100-kilometer recovery flight tests and the final orbital entry + recovery test missions
The Nebula-1 rocket that carried out this flight mission is Deep Blue Aerospace’s first commercial liquid rocket that can enter orbit and be recycled and reused. It is also an important carrier for breaking through and verifying rocket vertical recovery and reuse technology. The Nebula-1 rocket has a body diameter of 3.35 meters and a first-stage height of about 21 meters. It is equipped with the Thunder-R liquid oxygen-kerosene engine, China’s first reusable liquid rocket engine developed fully independently by Deep Blue Aerospace, with more than 90% of the main structure integrally formed using high-temperature alloy 3D printing technology.
This flight test is China’s first high-altitude recovery test of a launch vehicle that can enter orbit. The core mission of the test is to verify the correctness and coordination of the various systems in the vertical recovery phase after the Xingyun-1 enters orbit, especially to verify the multi-machine to single-machine variable power condition for the first time in flight, so as to accumulate key data for the subsequent 100-kilometer recovery flight test and the final orbital entry + recovery test mission.
According to the “Xingyun-1 First High-Altitude Vertical Recovery Flight Test Outline”, the key technical points verified during this test are as follows:
The rocket took off with three engines ignited according to the predetermined procedure. After reaching the predetermined height, the engines on both sides were shut down, and the attitude was stabilized and the ascent was slowed down by relying on the thrust of a single engine. After reaching the highest point, it relied on the thrust adjustment of a single engine to descend smoothly. After moving sideways for about 200 meters, it successfully unlocked, deployed and locked the landing legs at the predetermined height above the recovery site. However, an abnormality occurred during the final landing shutdown phase, resulting in partial damage to the rocket body. The entire flight test lasted 179 seconds. Before shutdown, the error between the rocket body and the theoretical landing point was less than 0.5 meters, and the rocket body finally landed precisely at the center of the recovery site. The flight mission profile of this test was consistent with the predetermined procedure. The entire process of test preparation and implementation was within the scope of the preliminary safety control plan. After the test, post-processing was carried out in accordance with the predetermined emergency response process, and no safety issues occurred throughout the process.
After the test, a preliminary retrospective analysis of the test process data showed that during the final landing shutdown phase, the engine thrust servo followed the control command abnormally, causing the rocket body to land at a height exceeding the design range and partial damage to the rocket body. The Deep Blue Aerospace technical team will complete the mission “zeroing” as soon as possible to lay a solid foundation for the success of subsequent recovery flight tests. Based on the summary of this test and the zeroing of technical faults, Deep Blue Aerospace will perform a high-altitude vertical recovery mission again in November.
This flight test was conducted at the Ejin Banner Spaceport built by Deep Blue Aerospace. The ground equipment, refueling system, and measurement and control system of the test site were all independently developed by Deep Blue Aerospace. The test site is the first fully commercial test site in China that can meet the needs of liquid rocket launches and flight tests. It is located in the heart of the Gobi Desert, adjacent to the Badain Jaran Desert, China’s third largest desert, on the south side. The surrounding area is a vast Gobi Desert uninhabited area, which has inherent safety characteristics. The test area this time points to the uninhabited area in the desert to the south. The test is strictly carried out in accordance with the safety management requirements of rocket tests, and comprehensive risk identification, control, and emergency plans are carried out to ensure the test safety and public safety of this test.
For the first stage of the Nebula-1 orbital rocket, only less than 1/5 of the propellant was added in this test; the precise attitude control of the propellant shallow box in the high-altitude vertical recovery condition was successfully verified. This test used high-precision self-alignment technology based on a dynamic base, as well as takeoff roll-to-launch launch technology, which can meet the full-direction launch requirements without changing the vertical installation state of the rocket. In the future, it can greatly simplify the workload of different flight missions and improve adaptability. This test preliminarily verified the recovery trajectory optimization based on optimal control and the meter-level precision guidance algorithm, and conducted engineering verification for the subsequent orbital entry + recovery optimal control method.
This test is the first time in China that an open-cycle liquid oxygen-kerosene pintle engine has been used to perform a rocket high-altitude recovery test mission. The liquid oxygen-kerosene propellant combination has the characteristics of high comprehensive carrying efficiency, low product cost, safety in use and good maintainability, and is the only choice for liquid recovery rockets for commercial use; but due to the difficulty of kerosene liquid-liquid combustion, smooth thrust regulation and stable combustion have always been the difficulties of kerosene thrust regulation engines. Pintle technology, as the best engineering practice to solve the thrust regulation of kerosene engines, is one of the technical peaks of open-cycle liquid engines. The success of this test is the first time that the Lei Ting-R engine has participated in a flight test. The central engine has carried out thrust regulation throughout the 179s flight. The actual thrust regulation command range is from 110% to 58%, and the thrust regulation accuracy is better than 1%. Under flight conditions, it responds well to step commands with a maximum amplitude of 40%, and the thrust overshoot accuracy is less than 2%.
This test was the first in China to use a landing cushion mechanism (landing legs) developed specifically for orbital-stage rockets for vertical recovery testing. In order to meet the stringent weight requirements of orbital-stage rockets, the mechanism is made of a full carbon fiber structure. In the early stages, single-machine tests of the buffer, single-machine tests of the connection and locking device, a series of deployment and retraction tests of a single leg, and joint deployment and retraction tests of four legs and the rocket body were carried out. Single-machine and system tests. Based on a series of previous tests and improvements, this mechanism is the first landing cushion device product in China to enter engineering applications. At the cost of a weight of no more than 1.2t and less than 10% of the rocket’s empty weight, the first stage of the rocket can land safely and reliably with a total weight of no more than 15 tons, a speed of no more than 3m/s, and an attitude angle of no more than 5° under the condition of carrying the remaining propellant.
In the future, Deep Blue Aerospace will continue to adhere to the serious safety awareness, rigorous and pragmatic scientific attitude, and the pursuit of excellence in innovation, focusing on the fundamental purpose of providing safer, economical, reliable, and high-frequency space transportation services, and accelerate the promotion and realization of the rapid installation of China’s reusable rockets. After accumulating valuable experience this time, Deep Blue Aerospace firmly believes that in the near future, reusable rockets will soar into the sky and help China’s aerospace “increase in volume”.
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