Space Pioneer Details Cause of Tianlong-3 RMB 1 First-Flight Failure

Space Pioneer has released a closed-loop review of the failed maiden flight of the Tianlong-3 RMB 1 launch vehicle, five months after the mission. The company said it will not lower the rocket's overall performance in order to secure success.

Zhang Jianhong said that one issue drawing attention before the flight test was "ground-to-space consistency" — whether ground tests can fully cover the real environment after launch. The attitude control system was verified on the ground through simulation modeling, while the dynamic characteristics in actual flight require flight tests for confirmation. Coupling effects among the aerodynamic environment, thermal protection system, structure and other systems under real flight conditions are difficult for ground tests of individual systems to fully cover; only in a full-vehicle real flight environment can they be verified 100%.

Regarding the cause of the failure, Space Pioneer proposed three core improvements. First, optimize the liquid-oxygen discharge angle, changing it from vertical to lateral discharge to help the liquid oxygen dissipate as quickly as possible and reduce the probability of being drawn downward. Second, adjust the thermal protection structure, replacing the original metal heat shield with a composite thermal protection structure, and changing the large-area flexible thermal protection skirt to a scheme based mainly on rigid thermal protection with flexible protection retained locally. Third, optimize the layout of the relevant pipelines and add sensor measurement points to obtain more data in subsequent flights. The development team conducted an engine hot-fire test with the relevant configuration, successfully reproducing the complete process of liquid-oxygen suction triggering secondary combustion, with the failure development chain fully consistent with flight telemetry data. The team then carried out a hot-fire test assessment of about 200 seconds under the improved configuration. Normal first-stage flight lasts about 145 seconds, so the 200-second test fully covered first-stage flight conditions, and the test results showed the thermal protection structure was in good condition.

The Tianlong-3 RMB 2 rocket has completed final assembly and overall testing, and its technical configuration is in the freeze stage. It will subsequently complete various special reviews under the release standards applied within the system before leaving the factory. During the RMB 1 mission, multiple key innovative technologies of Tianlong-3 were tested under real conditions. The country's largest large-slenderness-ratio structure, with a slenderness ratio of 19.0, and the flight attitude control technology were verified. The large slenderness ratio increases payload capacity but also intensifies elastic vibration and attitude control difficulty; data from the RMB 1 rocket indicate that technologies such as elastic adaptive stability control effectively solved this problem. The Tianhuo-12 engine, with a single-engine sea-level thrust of 95 tonnes, performed stably, verifying the reliability of the country's highest-thrust and highest thrust-to-weight liquid oxygen kerosene engine. The world's first liquid-nitrogen vaporization pressurization scheme and the country's first gas-injection accumulator technology both demonstrated effects in reducing cost, reducing weight and suppressing longitudinal coupling vibration during flight.

Zhang Jianhong said the core technical configuration of the RMB 2 rocket remains consistent with RMB 1, with the focus on verifying the effectiveness of the corrective measures. Although reliability measures such as pipeline optimization were added, no compromise was made in performance. Tianlong-3 can carry out a 36-satellite launch on a single rocket, and its greater payload capacity can adapt to different orbits, different payloads and different mission requirements. Space Pioneer is strengthening full-vehicle, full-process risk control and distilling the closed-loop review experience into executable mechanisms and standards.