Olga Ozhogina is a Ukrainian space reporter, journalist and photojournalist. She contributed this article to Space.com Expert Voices: Op-Ed and Insights through the press center of Promin Aerospace, a Ukrainian rocket startup.
ukrainian rocket company Promin Aerospace (opens in new tab), which is currently developing an ultralight autophagic launch vehicle, has carried out a new series of studies on its unique engine. The startup’s initial tests showed the feasibility of the technical concept. With each new experiment, engineers are improving the design by testing different variations of the engine package.
The concept of rocket is based on the autophagic, or “self-devouring” technology, which was initially proposed by Promin Aerospace’s technical director, Vitaliy Yemets.
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In an autophagic rocket, the hull would be used as solid rocket fuel, in addition to other propellants carried on board. For this purpose, the hull material must be strong enough and have sufficient combustibility. During the rocket’s flight, the body is consumed, allowing for a reduction in mass as it travels and leaving no debris when the flight is complete. This advance would enable more efficient and ecologically correct launches.
Over the course of two months, three experiments were carried out with different variations of the engine and nozzle design, which allowed Promin Aerospace to identify and investigate challenges as well as improve the overall performance of the package. As the engine technology is unique, all tests had to be designed by the engineering team from the ground up, detecting and eliminating defects.
Thanks to these three initial 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 recorded.
The fourth experiment: a fuel supply system
For the fourth experiment, the engineering team used the same oxidizing agent that was used in the third experiment, as well as a bell-shaped nozzle, to keep the variables consistent in the new test. In addition, the engineers used a polymer fuel rod and a gas-oxygen mixture to start. They used various temperature probes to monitor the temperature in various areas of the engine and pressure gauges in the combustion chamber and pneumatic cylinder.
After previous experiments, the pushrod was fed into the gasifier while recording the burning parameters with various sensors. The starting fuel and fuel pack feed systems have been shown to function reliably; no problems with achieving combustion were recorded, and the initial component of the experiment provided a higher pressure compared to previous experiments.
As 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 turned off in 203 seconds (3 minutes and 23 seconds).
The measured feed rate was 10 millimeters per second (mm/s), demonstrating 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 rate of 10 mm/s and 12 atm.
The experiment lasted approximately 280 seconds (4 minutes and 40 seconds). At 252.95 seconds, a beacon moved out of the feed path, followed by a pop and the end of the assembly’s movement. No damage was done to the engine or the mounting bracket, and the results of the experiment show that everything worked fine, although some minor changes should take place. For the next test, the inlet seal of the assembly has been improved
Overall, the system worked reliably and provided sufficient pressure in the combustion chamber. Combustion of components in run mode provided a higher pressure than starting fuel. So far, all experiments allowed the development of an efficient and safe concept.
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the fifth experience
For our fifth experiment, the engineering team used another type of fuel and oxidizer, but kept using the bell-shaped nozzle. The test was carried out similarly to the previous ones, with the initial mixture being supplied at 4 atm pressure and turned off in 204 seconds (3 minutes and 24 seconds), with the new primary fuel supplied under 9 atm pressure.
The pressure inside the combustion chamber dropped after the starting fuel was turned off, but gradually increased to 10 atm, and in 248 seconds (4 minutes, 8 seconds) the engine temperature reached the operating level. At 252 seconds (4 min 12 seconds) the pressure went out of scale and the fuel pack stopped. Upon investigation, engineers determined that the pressure rise was caused by a blockage in the nozzle as the carbonator housing was torn off.
Despite this, the engineers found that the chosen starting fuel set worked reliably. The pressure in the combustion chamber was correlated with the feed rate of the working components with a delay in the reaction time.
The sixth experience: the new fuel rod component
The sixth experiment was carried out with the initial mixture being supplied under a pressure of 4 atm and it was turned off in 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 approximately 300 seconds (5 minutes) when a flare ignited in 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 the heat sensors and color charts, it reached a temperature of about 1,830 degrees Fahrenheit (about 1,000 degrees Celsius). The feed rate of this fuel set was uneven, with a maximum value of 14 mm/s. The experiment lasted 350 seconds (5 minutes and 50 seconds).
Overall, the experiment took place with pressure within limits and without uncontrolled explosions, proving the reliability of this construction variant.
“Using the new polymer as the main fuel component was efficient and safe, as there was no critical increase in pressure. the combustion chamber,” Yemets said.
The next experiment will be dedicated to testing the new oxidant. It is expected to increase combustion efficiency.
After final testing, 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 Vitaly Yemets (opens in new tab) and Misha Rudominski (opens in new tab) in 2021. That same year, the company closed its first round of investments and proved the capabilities of autophagic technology, which can reduce launch costs and space debris.
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