Olga Ozhogina is a Ukrainian space reporter, journalist and photojournalist. She contributed to this article Space.com’s expert votes: Op-Ed & Insights via the press center at Promin Aerospace, a Ukrainian rocket launch.
Ukrainian rocket launcher Promin Aerospace, which is currently developing an ultralight, autophagic launch vehicle, has conducted a new series of studies on its unique engine. The startup’s initial tests, as described here, showed the feasibility of the technical concept. With each new experiment, engineers improve the design by testing different variants of the engine unit.
The concept of rocket is based on autophagic, or “self-consuming” technology, originally proposed by Promin Aerospace’s chief technology officer Vitaliy Yemets.
In an autophagic rocket, the hull would be used as solid rocket fuel, in addition to other fuels transported on board. For this purpose, the hull material must be both sufficiently strong and have sufficient flammability. During the flight of the rocket, the body is consumed, which enables a reduction of the mass when it travels and leaves no debris when the flight is complete. This progress would enable more efficient and environmentally friendly launches.
During two months, three experiments were performed with different variants of engine and nozzle design, which enabled Promin Aerospace to identify and investigate challenges, as well as to improve the overall performance of the unit. Because the engine technology is unique, all tests must be designed by the engineering team from the ground up, while defects are detected and eliminated.
Thanks to these first three tests, it was possible to improve the fuel supply system and test new fuel components, which proved their safety and efficiency. All necessary parameters were measured and registered.
The fourth experiment: a fuel supply system
For the fourth experiment, the engineering team used the same oxidant used in the third experiment, as well as a bell-shaped nozzle, to keep the variables consistent in the new test. In addition, engineers used a polymer fuel rod and a gas-oxygen mixture for a starter motor. They used several temperature probes to monitor the temperature in many engine areas and pressure gauges in both the combustion chamber and the pneumatic cylinder.
After previous experiments, the fuel rod was fed into the carburettor while the firing parameters were registered with several sensors. The starter fuel and fuel cartridge feed system proved to work reliably; no problems in achieving combustion were recorded, and the starting component of the experiment gave a higher pressure compared to previous experiments.
When the starting fuel was supplied, a pressure of 4 atmospheres (atm) was registered in the combustion chamber. The fuel supply pressure remained stable between 9 and 9.5 atm, and the starting fuel was shut off at 203 seconds (3 minutes and 23 seconds).
The measured feed rate was 10 millimeters per second (mm / s), indicating adequate performance, and the pressure reached a maximum of 12 atm. This experiment remained stable for 252.95 seconds (4 minutes and 12.95 seconds) at a speed of 10 mm / s and 12 atm.
The experiment lasted for about 280 seconds (4 minutes and 40 seconds). At 252.95 seconds, a flame left the feed path, followed by a clicking sound and the end of the unit’s movement. No damage was caused to the engine or bracket, and the experimental results show that everything worked well, although some minor changes had to be made. For the next test, the mounting inlet seal was improved
Overall, the system worked reliably and provided sufficient pressure in the combustion chamber. Combustion of components in operating mode gave a higher pressure than starting fuel. So far, all experiments have enabled the further development of an efficient and safe concept.
Related: The history of rockets
The fifth experiment
For our fifth experiment, the engineering team used a different type of fuel and oxidant but retained the use of the bell-shaped nozzle. The test was performed in a similar manner to the previous ones, where the starting mixture was applied under a pressure of 4 atm and switched off at 204 seconds (3 minutes and 24 seconds), with the new primary fuel added under a pressure of 9 atm.
The pressure in the combustion chamber decreased after the starting fuel was switched off but gradually increased to 10 atm, and after 248 seconds (4 minutes and 8 seconds) the engine temperature had reached the operating level. At 252 seconds (4 min and 12 seconds) the pressure went off the scale and the fuel assembly stopped. After examination, the engineers found that the pressure increase was caused by a block in the nozzle, because the carburetor casing was torn off.
Despite this, the engineers found that the selected starter fuel assembly worked reliably. The pressure in the combustion chamber was correlated with the feed rate of the working components with a delay of the reaction time.
The sixth experiment: the new fuel rod component
The sixth experiment was performed with the starting mixture applied under a pressure of 4 atm and turned off at 188 seconds (3 minutes and 8 seconds). It used a new primary fuel, which was supplied under a pressure of 25 atm. The pressure inside the combustion chamber remained at 8.5 atm until about 300 seconds (5 minutes) when a flame ignited at the fuel assembly supply unit at the bottom of the combustion chamber.
At that moment, the combustion chamber began to overheat and the steel turned white. According to both the sensors and the thermal color charts, it reached a temperature of about 1,830 degrees Fahrenheit (about 1,000 degrees Celsius). The feed rate for this fuel assembly was uneven, with a maximum value of 14 mm / s. The experiment lasted 350 seconds (5 minutes and 50 seconds).
Overall, the experiment went with pressure within limits and without uncontrolled explosions, which proved the reliability of this variant of the design.
“The use of the new polymer as the main fuel component was efficient and safe, as there was no critical increase in pressure. So we will consider this variant. After that test, the assembly inlet seal will be tightened more to prevent overheating of the combustion chamber,” in Yemets.
The next experiment will be devoted to testing the new oxidant. It is expected to increase combustion efficiency.
After conducting final tests, Promin Aerospace plans to conduct the first test launch of its suborbital rocket, followed by its first commercial mission in early 2023. In the future, the company also plans to conduct orbital launches.
Promin Aerospace (opens in new tab) was established by Vitaliy Jemets (opens in new tab) and Misha Rudominski (opens in new tab) 2021. In the same year, the company completed its first round of investment and proved the ability of autophagic technology, which could reduce launch costs and space debris.
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