Today, November 15, marks the 22nd anniversary of the first and only flight of our reusable transport spacecraft "Buran". And also the second and last flight of the Energia super-heavy launch vehicle.
Regular readers know that this event cannot pass by my attention, since I took part in the work on "Buran", working in the Moscow experimental design bureau "Mars". Although not at the most "cutting edge". There was a banquet in the hotel "Ukraine", where we celebrated this event, truly great for us. And there were plans for the next flight, also unmanned, but much longer, and there was work on these plans.
And then there was a murky timelessness, and then, in 1993, the program was closed …
I have not yet written about the Buran itself, although the chapter about it is the next in my unfinished series about the history of projects of manned reusable ships. However, he wrote about the history of its creation, and also about the Energia rocket. And now I will not write about "Buran" as such, because it should not be a blog post, but a real article, or maybe more than one. But I will try to show the area of responsibility of our department.
We did what provided the USSR, probably the only clear priority for everyone over the American shuttle. We, our department, made the algorithmic and software complex for the automatic landing "Buran". As far as I know, the Americans have such a regime, but have never been used. Their shuttles were always landed by pilots.
Now, as I understand it, the task of landing without the participation of the crew has been solved - after all, drones, including large ones, are landing. But, in my opinion, passenger airliners still do not land “automatically”. And then, I know for sure, well-equipped airfields could bring well-equipped airliners to a height of 15 meters. Next is the crew. The task was aggravated by the fact that the aerodynamic quality of "Buran" on subsonic was about half the quality of the then passenger aircraft - 4, 5 versus 8-10. That is, the ship was "twice as close to the iron" as a normal swept passenger plane. Which is not surprising when you compare their shape.
Automatic landing of a 100-ton whopper is a very difficult thing. We did not do any hardware, only the software for the landing mode - from the moment of reaching (during descent) an altitude of 4 km to stopping on the runway. I will try to tell you very briefly how this algorithm was made.
First, the theorist writes the algorithm in a high-level language and tests it against test cases. This algorithm, which is written by one person, is "responsible" for one relatively small operation. Then it is combined into a subsystem, and it is dragged to the modeling stand. In the stand "around" the working, on-board algorithm, there are models - a model of the dynamics of the apparatus, models of executive bodies, sensor systems, etc. They are also written in a high-level language. Thus, the algorithmic subsystem is tested in the "mathematical flight".
Then the subsystems are put together and checked again. And then the algorithms are "translated" from a high-level language into the language of the on-board vehicle (BCVM). To check them, already in the hypostasis of the onboard program, there is another modeling stand, which includes an onboard computer. And around her is the same - mathematical models. They are, of course, modified compared to the models in a purely mathematical bench. The model "spins" in a general purpose mainframe. Do not forget, these were the 1980s, personal cars were just beginning and were very low-powered. It was the mainframe time, we had a pair of two EC-1061s. And for communication of an on-board vehicle with a mathematical model in a universal computer, special equipment is needed; it is also needed as part of a stand for various tasks.
We called this stand semi-natural - after all, in it, besides all mathematics, there was a real on-board computer. It implemented the mode of operation of the onboard programs, very close to the real-time mode. It takes a long time to explain, but for the on-board computer it was indistinguishable from the "real" real time.
Someday I'll get myself together and write how the semi-natural modeling mode works - for this and other cases. In the meantime, I just want to explain the composition of our department - the team that did all this. It had a complex department that dealt with the sensor and executive systems involved in our programs. There was an algorithmic department - these actually wrote on-board algorithms and worked them out on a mathematical bench. Our department was engaged in a) translation of programs into the on-board computer language, b) creation of special equipment for a semi-natural stand (here I worked) and c) programs for this equipment.
Our department even had our own designers to make documentation for the manufacture of our blocks. And there was also a department that was in charge of operating the aforementioned EC-1061 pair.
The output product of the department, and therefore of the entire design bureau within the framework of the "storm" theme, was a program on magnetic tape (1980s!), Which was taken to work out further.
Further - this is the stand of the enterprise-developer of the control system. After all, it is clear that the control system of an aircraft is not only an on-board computer. This system was made by a much larger enterprise than us. They were the developers and "owners" of the on-board computer, they stuffed it with a multitude of programs that perform the whole range of tasks to control the ship from pre-launch preparation to post-landing shutdown of systems. And for us, our landing algorithm, in that on-board computer, only a part of the computer time was allocated, in parallel (more precisely, I would say, quasi-parallel) other software systems worked. After all, if we calculate the landing trajectory, this does not mean that we no longer need to stabilize the apparatus, turn on and off all kinds of equipment, maintain thermal conditions, generate telemetry and so on, and so on, and so on …
However, let's get back to working out the landing mode. After working out in a standard redundant on-board computer as part of the entire set of programs, this set was taken to the stand of the enterprise-developer of the Buran spacecraft. And there was a stand, called a full-size stand, in which an entire ship was involved. When programs were running, he waved elevons, hummed drives and all that stuff. And the signals came from real accelerometers and gyroscopes.
Then I saw enough of all this on the Breeze-M accelerator, but for now my role was quite modest. I did not travel outside my design bureau …
So, we passed the full-size booth. Do you think that's all? No.
Next was the flying laboratory. This is the Tu-154, whose control system is configured so that the aircraft reacts to the control actions generated by the on-board computer, as if it were not a Tu-154, but a Buran. Of course, it is possible to quickly "return" to normal mode. "Buransky" was switched on only for the duration of the experiment.
The culmination of the tests were 24 flights of the Buran, made especially for this stage. It was called BTS-002, had 4 engines from the same Tu-154 and could take off from the runway itself. He sat down in the process of testing, of course, with the engines turned off, because "in the state" the spacecraft sits in the gliding mode, there are no atmospheric engines on it.
The complexity of this work, or rather, our software-algorithmic complex, can be illustrated by the following. In one of the BTS-002 flights. flew "on the program" until the main landing gear touched the strip. Then the pilot took control and lowered the nose strut. Then the program turned on again and kept the device to a complete stop.
By the way, this is pretty understandable. While the apparatus is in the air, it has no restrictions on rotation around all three axes. And it revolves, as expected, around the center of mass. Here he touched the strip with the wheels of the main struts. What's happening? Roll rotation is now impossible at all. Pitch rotation is no longer around the center of mass, but around the axis passing through the points of contact of the wheels, and it is still free. And the rotation along the course is now determined in a complex way by the ratio of the steering torque from the rudder and the friction force of the wheels on the strip.
This is such a difficult regime, which is so radically different from both flight and run along the lane "at three points". Because when the front wheel falls into the lane, it’s like in an anecdote: no one is spinning anywhere …
… I will add that the problems, understandable and incomprehensible, from all stages of testing were brought to us, analyzed, eliminated and again went along the entire line, from the mathematical stand to the BTS in Zhukovsky.
Well. Everyone knows that the landing was flawless: a time error of 1 second - after a three-hour flight! - deviation from the axis of the strip 1, 5 m, in range - some tens of meters. Our guys, those who were in the KDP - this is a service building near the strip - said that the feelings were - words cannot be expressed. Still, they knew what it was, how many things worked right there, what millions of interrelated events happened in the right relationship for this landing to take place.
And I will also say: "Buran" is gone, but the experience has not disappeared. This job has grown a splendid team of first-class specialists, mostly young. The charge from it was such that the team did not fall apart to the ground in difficult years, and this made it possible just at that time to create a control system for the upper stage "Breeze-M". It was no longer a software system, there was already our own onboard computer, and the blocks that controlled all the onboard machinery - engines, squibs, related systems of other developers, etc. And we did the ground complex for checking and prelaunching the upper stage.
Of course, "Breeze" was made by KB for everyone. But a very important role, primarily in the creation of the software complex, was played by the people of Buran - people who built and perfected in the course of the Buran epic the very technology of doing a lot of work with the participation of hundreds of specialists from dozens of different profiles. And now the design bureau, which has proven its worth, has a lot of work …
