Air-Breathing Rocket Engine
Every time I sit in an airplane, as the engines are spooled-up and the craft accelerates down the runway, I think - "wouldn't it be amazing if the plane could just continue upwards straight into orbit and dock with the International Space Station". Anyone else had such thought before?
For such a dream to become a reality, one would need a spaceplane. It is essentially an airplane that is capable of Single-Stage to Orbit (SSTO) - that is, it can reach orbit on a single tank of fuel. Modern rocket and fuel storage technology prohibit the construction of such a vehicle so all of today's most advanced rockets consist of at least two stages. But we can still contemplate about what sort of engine would be required to accomplish an SSTO flight.
On first thought, the idea could be to construct an airplane with small wings, lightweight tanks and a cluster of small rocket motors. NASA and Lockheed Martin attempted to build this very type of vehicle, called the X-33 project. But this project failed at the early stages of development. The resulting vehicle simply did not have sufficient energy storage onboard to make it into orbit.
Some years later, a UK-based company, Reaction Engines, recognized that in order to decrease the total fuel and oxidizer requirement for such a flight, oxygen should be extracted out of the atmosphere on the way up. It is a good idea, since air also contains a lot of nitrogen (80% nitrogen, 20% oxygen) that can be readily used as extra fluid for thrust. So Reaction Engines decided to build an Air-Breathing Rocket Engine. Their engine integrates an inlet and an air-compressor with a cluster of small rocket motors. Basically, during atmospheric flight, super-cooled air from the atmosphere will be pumped into the rocket motors instead of the liquid oxidizer that is stored onboard. Unfortunately, this design also has a lot of deficiencies. For one, the compressor is so small there is barely any thrust production at take-off. Also, cooling atmospheric air at hypersonic speeds is a very difficult task since the entire plane and engine get extremely hot.
领英推荐
What really is needed here is a Quadbrid jet-engine that combines four engines (modes) into one. The first three modes rely on the atmosphere to get the aircraft up to speed: turbojet mode gets the aircraft from the runway to Mach 1 (Mach = speed of sound at sea level), ramjet mode continues from Mach 1 to Mach 4, and finally the scramjet mode takes-over for a boost from Mach 4 to Mach 10. The combination of these first three modes was covered in a previous edition (see "Tribrid jet-engine"). The Quadbrid jet-engine adds yet a forth mode to the Tribrid jet-engine - a rocket mode. Once the scramjet begins running out of air, the engine switches from external oxygen source to an internal tank and boosts the aircraft from Mach 10 to a final orbital velocity of Mach 25. At this speed, the spaceplane will be able to catch-up and dock with a space-station in Low Earth Orbit.
But combining a rocket-motor and a jet-engine into the same unit is a very complex task because the jet-engine is air-breathing and is inherently open to the environment while the rocket motor is fully isolated. The most practical solution is to take a Mach 10 capable Tribrid jet-engine (which could take decades to develop) and bolt an ordinary liquid rocket motor right next to it. At Mach 10, the Tribrid shuts down and the rocket motor takes over. This sort of combination would provide the needed propulsion to get the spaceplane into orbit. But let's not forget that building the rest of the spaceplane remains largely an unsolved mystery. Cryogenic fuel storage and aircraft structures would both require some truly ground-breaking innovations to become light enough to enable "flying to space on a single tank".
Engineer Darkworks USA
1 年Dang really starting to have doubts about this ever getting off the ground. My God FLY SOMETHING!!!!! Even subscale. The real lab is up there. Only learn so much on the ground.
President, BSRD LLC and Aviation & Aerospace Consultant
1 年Alex, thanks for sharing your thoughts regarding spaceplanes. After many years of working on combined cycle engines (the ATR engine, for example), I still feel that an airbreathing propulsion component to space access could be the enabling technology for such systems and, coupled to spaceplane configurations, could provide safe, and economically viable transportation to orbit. This is why I've been working on the Turborocket engine ( youtube: https://www.youtube.com/channel/UCFPNi2Ae4qxDYM5fD-PEFRg ). This simple, open-source engine cycle can operate as a high performance pump-fed rocket engine, but its true virtue is that it can be integrated into existing airbreathing engines (like turbojets) to provide unique, high performance turbine based combined cycle engine (TBCC) configurations. We're using turborocket-based TBCC engine configurations to power our homebuilt spaceplane prototypes, and even though they are far from orbital flight speeds, their performance is still pretty good. You can see some of the concepts on the YT channel. Please continue to advocate for spaceplanes and airbreathing propulsion. And when you're ready to built your own turborocket engine, there's a book on the topic: ( https://a.co/d/95tLcYX ) !
Defense Autonomous Systems | T-Shaped, Generalized Specialist
1 年Do you take requests? The cyclorotor looks weird and interesting...
CEO – Space Orbital Systems
1 年All attempts to combine an aircraft and a rocket in order to obtain the advantages of an aircraft and a rocket in one design ended up with the fact that instead of an advantage, this design received the disadvantages of both.