March 25, 2019 at 06:48Not one Falcon - fundamentally different reusable ESA and ULA projects
SpaceX's reusable first stages of the Falcon launch vehicle have sparked a surge of interest in reusable rockets. And if, for example, the Chinese company LinkSpace demonstrates renderings of a similar system with landing on engines on folding supports, then other designers offer systems on different principles, using wings or air catch. Some projects have already managed to close, but there are also freshly announced ones.
Adeline Technology Demonstrator
In 2015, news appeared that Airbus Defense and Space are developing a reusable Adeline module, which is a winged unit with a first-stage rocket engine, as well as air engines and propellers to land on the runway. Most clearly, the concept is illustrated by a video that is no longer available on the official channel, but saved by ordinary users.
The idea of saving only the tail of the rocket has its advantages - engines, avionics and tail compartment equipment, according to Adeline developers, account for 80% of the cost of a step, and saving them is much simpler than a large step in its entirety. Fuel is also saved, and there is no overload experienced by a step when landing on engines. But, of course, everything has a price - the gain in fuel economy will be partially eaten by losses on the additional mass from the wings.
The tail part of the Adeline was offered for use in the Ariane 6, although, theoretically, it could be modified for other carriers. When the project was officially announced, it turned out that work has been ongoing since 2010, and successful testing of large-scale models has already been carried out. After the loud announcement, there was no abundance of news on the project - the priority of Airbus Defense and Space is the new Ariane 6 launch vehicle. And in 2018, information appeared that the project did not arouse interest for financial reasons.
The German Air and Space Center, part of ESA, on March 20 this year announced the start of work on the concept of a cruise missile stage, which will be caught and towed by a carrier aircraft. The project was called FALCon (Formation flight for in-Air Launcher 1st stage Capturing demonstration, “Flight in formation to demonstrate the pickup of the first stage of the carrier”), with the exception of the letter register, which coincides with the name of the Falcon SpaceX launch vehicle. Due to the coincidence of the names, the project manager Martin Sippel had to explain that the engineers were inspired by a falcon diving in order to grab the victim, not the SpaceX rocket.
FALCon workflow, DLR illustration
Landing a rocket stage on engines has a serious drawback - you have to separate the stage when there is still a lot of fuel left in it, which is then spent on landing. Worse, because of the Overt effect, it is this fuel that is most valuable for accelerating the payload. In the case of FALCon, a planning descent will allow you to spend all the fuel from the tanks - the towing plane will pull the stage before landing. But, of course, this gain, like the Adeline, will be eaten by the increased mass of the step due to the added wings.
An important element of the system will be the design for picking up and towing the step. Engineers mention the design of the steered dock / tow cone.
Guided Dock / Tow Cone
The cones of refueling planes familiar to us are uncontrollable - the pilots of refueling planes themselves catch them by maneuvering with their vehicles. This is not a quick and difficult matter, therefore, for a stage planning with the engines turned off, a controlled cone should significantly facilitate the task. But besides this, improvements for the towing aircraft are almost not required, and in this capacity it will be possible to use ordinary passenger airplanes, and b / y for greater cost savings.
FALCon work is at the very beginning, and, as in the case of Adeline, the first tests will be carried out with unmanned winged aircraft, and not rockets. So far, 2.6 million euros has been allocated for the project, this is not much, but enough for the first experiments. The terms of the project are quite long - the airworthiness of the system should be reached in the region of 2028 in order to possibly be used in the next generation step, which may appear in the region of 2035.
The Falcon 9 stage for landing performs as many as three engine starts - boostback burn, in which the stage takes aim at the landing area, entry burn, the braking stage so that it does not overheat, and the final landing inclusion. All three consume precious fuel, and despite the fact that parachutes cannot provide an accurate landing, they would weigh less than the fuel supply needed for these maneuvers. The idea of using parachutes and a helicopter intercept is going to be implemented by the ULA launch service provider in its Vulcan launch vehicle. The tail compartment of the first stage will have to be dropped, open a supersonic parachute for braking in dense layers of the atmosphere, drop it, open a guided parachute-wing, be picked up by a helicopter, delivered to the ground, tested and reused.
ULA Scheme
In the video:
The latest news on the project dates back to the beginning of August 2018, when ULA received $ 1.9 million from NASA to demonstrate the technology of air pickup of an object that returned from orbit.
The French National Center for Space Research (CNES) is also engaged in reusability experiments. Callisto is a technological demonstrator of a suborbital reusable stage with a rocket landing, comparable to GrassXper from SpaceX, but different in its oxygen-hydrogen engine.
CNES presentation frame
In the future, a full-fledged launch vehicle can grow out of this, but not soon - the priority of CNES is first to reduce the cost of developed launch vehicles, and then return stages. The approach is very robust, I recall that Musk first offered a competitive disposable Falcon 9, began to receive orders, and only then began to turn it into a reusable missile.
Another area of CNES's work is the Prometheus methane engine. Using new technologies, including 3D printing, they are going to make it 10 times cheaper than the Ariane 5 central block engine (second stage). If everything goes well, the engine will be used in the new Ariane 6 modification or the next ESA rocket.
Prometheus engine, CNES image
Experiments with various reusable rockets can only be welcomed by the phrase of the Chinese emperor Qin Shihuang (which was then reused by Mao Zedong): "Let a hundred flowers blossom, let a hundred schools compete." Each technical solution has its pros and cons, and let practice show which option is better.
Adeline Technology Demonstrator
Adeline is no more
In 2015, news appeared that Airbus Defense and Space are developing a reusable Adeline module, which is a winged unit with a first-stage rocket engine, as well as air engines and propellers to land on the runway. Most clearly, the concept is illustrated by a video that is no longer available on the official channel, but saved by ordinary users.
The idea of saving only the tail of the rocket has its advantages - engines, avionics and tail compartment equipment, according to Adeline developers, account for 80% of the cost of a step, and saving them is much simpler than a large step in its entirety. Fuel is also saved, and there is no overload experienced by a step when landing on engines. But, of course, everything has a price - the gain in fuel economy will be partially eaten by losses on the additional mass from the wings.
The tail part of the Adeline was offered for use in the Ariane 6, although, theoretically, it could be modified for other carriers. When the project was officially announced, it turned out that work has been ongoing since 2010, and successful testing of large-scale models has already been carried out. After the loud announcement, there was no abundance of news on the project - the priority of Airbus Defense and Space is the new Ariane 6 launch vehicle. And in 2018, information appeared that the project did not arouse interest for financial reasons.
Falcon, but not Falcon
The German Air and Space Center, part of ESA, on March 20 this year announced the start of work on the concept of a cruise missile stage, which will be caught and towed by a carrier aircraft. The project was called FALCon (Formation flight for in-Air Launcher 1st stage Capturing demonstration, “Flight in formation to demonstrate the pickup of the first stage of the carrier”), with the exception of the letter register, which coincides with the name of the Falcon SpaceX launch vehicle. Due to the coincidence of the names, the project manager Martin Sippel had to explain that the engineers were inspired by a falcon diving in order to grab the victim, not the SpaceX rocket.
FALCon workflow, DLR illustration
Landing a rocket stage on engines has a serious drawback - you have to separate the stage when there is still a lot of fuel left in it, which is then spent on landing. Worse, because of the Overt effect, it is this fuel that is most valuable for accelerating the payload. In the case of FALCon, a planning descent will allow you to spend all the fuel from the tanks - the towing plane will pull the stage before landing. But, of course, this gain, like the Adeline, will be eaten by the increased mass of the step due to the added wings.
An important element of the system will be the design for picking up and towing the step. Engineers mention the design of the steered dock / tow cone.
Guided Dock / Tow Cone
The cones of refueling planes familiar to us are uncontrollable - the pilots of refueling planes themselves catch them by maneuvering with their vehicles. This is not a quick and difficult matter, therefore, for a stage planning with the engines turned off, a controlled cone should significantly facilitate the task. But besides this, improvements for the towing aircraft are almost not required, and in this capacity it will be possible to use ordinary passenger airplanes, and b / y for greater cost savings.
FALCon work is at the very beginning, and, as in the case of Adeline, the first tests will be carried out with unmanned winged aircraft, and not rockets. So far, 2.6 million euros has been allocated for the project, this is not much, but enough for the first experiments. The terms of the project are quite long - the airworthiness of the system should be reached in the region of 2028 in order to possibly be used in the next generation step, which may appear in the region of 2035.
Different parachutes from ULA
The Falcon 9 stage for landing performs as many as three engine starts - boostback burn, in which the stage takes aim at the landing area, entry burn, the braking stage so that it does not overheat, and the final landing inclusion. All three consume precious fuel, and despite the fact that parachutes cannot provide an accurate landing, they would weigh less than the fuel supply needed for these maneuvers. The idea of using parachutes and a helicopter intercept is going to be implemented by the ULA launch service provider in its Vulcan launch vehicle. The tail compartment of the first stage will have to be dropped, open a supersonic parachute for braking in dense layers of the atmosphere, drop it, open a guided parachute-wing, be picked up by a helicopter, delivered to the ground, tested and reused.
ULA Scheme
In the video:
The latest news on the project dates back to the beginning of August 2018, when ULA received $ 1.9 million from NASA to demonstrate the technology of air pickup of an object that returned from orbit.
Prometheus and Callisto
The French National Center for Space Research (CNES) is also engaged in reusability experiments. Callisto is a technological demonstrator of a suborbital reusable stage with a rocket landing, comparable to GrassXper from SpaceX, but different in its oxygen-hydrogen engine.
CNES presentation frame
In the future, a full-fledged launch vehicle can grow out of this, but not soon - the priority of CNES is first to reduce the cost of developed launch vehicles, and then return stages. The approach is very robust, I recall that Musk first offered a competitive disposable Falcon 9, began to receive orders, and only then began to turn it into a reusable missile.
Another area of CNES's work is the Prometheus methane engine. Using new technologies, including 3D printing, they are going to make it 10 times cheaper than the Ariane 5 central block engine (second stage). If everything goes well, the engine will be used in the new Ariane 6 modification or the next ESA rocket.
Prometheus engine, CNES image
Conclusion
Experiments with various reusable rockets can only be welcomed by the phrase of the Chinese emperor Qin Shihuang (which was then reused by Mao Zedong): "Let a hundred flowers blossom, let a hundred schools compete." Each technical solution has its pros and cons, and let practice show which option is better.