Automatic planting stoton iron or who do you work with?
I will continue the "space" theme in their posts. This time I want to talk about one little-known aspect of the Energy-Buran program, namely, about the system of automatic landing of an orbital ship.
A lot has been written about the “Energy - Buran” program, I would recommend to all who are interested to immediately go to the special website buran.ru , on which there is a lot of reliable information.
To sum up briefly, the Energy-Buran program provided for the creation of a universal heavy launch vehicle Energia of the one-hundredth class and, as a payload for it, the orbital reusable spacecraft Buran.
')
The Buran ship was in many ways analogous to the American Space Shuttle system: a winged and tailless glider, tiled thermal protection, a cargo hatch, similar mass-dimensional parameters (output 30 tons and return from orbit 20 tons of cargo, crew up to 7 cosmonauts), but because equipment does not stand still, and our ship was developed later, and had significant differences. The Buran, unlike the American counterpart, was originally intended for docking with orbital stations and other ships, had a crew rescue system (its absence destroyed the crew of the Challenger at one time), and, most importantly, could perform the tasks of entering space , work in orbit and landing in fully automatic mode.
Let us leave outside the scope of this article the stages of take-off, entering orbit and maneuvering, docking and working with a payload. Consider more landing.
As the writer Lukyanenko once aptly noted in the book “Stars - Cold Toys”, the landing of the Buran is performed with the “grace of a falling iron iron.” In this ironic phrase, of course, there is a sense.
In general, the landing of an orbital cruise ship can be divided into four stages:
The descent from orbit is performed quite simply - the ship turns into a “tail forward, back to back” position, the cruise engines give an impulse that reduces speed below the orbital threshold, and the ship begins to go out of orbit. The engines of orientation at the time of entry into any dense layers of the atmosphere, and in our case this occurred at an altitude of about 100 kilometers above South America, turn the ship into the correct “airplane” position. From the moment of entry into the atmosphere until the moment of landing it takes about 30 minutes, during this time the ship must completely cancel the orbital speed (about 8 km / s), reach the specified landing area and land on the runway.
The task of the next stage is to reach a given point in the vicinity of the landing aerodrome with a given speed and orientation. The task is complicated by several points: firstly, the ship flies in a cloud of plasma most of the time and does not have the ability to communicate with the ground, secondly, by the time aerodynamic deceleration in the atmosphere begins, fuel for the cruise engine is already developed, therefore the speed increase maneuver is not possible when detecting undershoot Only the ship's glider can be controlled with the help of low-thrust and elevon steering engines.
Figuratively speaking, in order to quench the excess speed during the flight, the control system should slightly nose up, the aerodynamic drag will increase and the speed will decrease, and to compensate for the undershoot - on the contrary, lower the nose. This, of course, is a very rough approximation, but in fact it is correct.
The outcome of the second stage should be an exit to a point in the vicinity of the landing airfield at an altitude of about 4 kilometers and at a speed slightly above 300 km / h. At a higher speed, the Buran will be too inertial and will not be able to perform the maneuvers necessary for landing, and at a lower speed, it will simply fall into an uncontrolled dive due to its low aerodynamic quality (“falling iron iron with wings”).
Then comes the most difficult stage of landing - the exit on the runway. Automation, using ship sensors, readings of beacons and the flow of information from the ground control center, must understand where the ship is currently located, assess the strength and direction of the wind in the landing area, decide from which end of the runway to land and enter the lane. A speed error of no more than 20 km / h was allowed, a runway error of no more than 700 meters, a lateral deviation of no more than 38 meters.
To control the landing process, in addition to ground-based monitoring and control, we used our own on-board digital computer (On-board digital computer) Burana Beads-4. The military order determined the architecture of the onboard computer - it was implemented as four parallel independent computing channels and a comparator, which continuously compared the results at the output of the channels. In case of deviation of the results of any of the channels from the other three, it was turned off and the on-board computer continued to operate in the normal mode. In the same way, another damaged computational channel could be disabled, thus achieving automatic backup and fault tolerance of the on-board computer. Computing channels (or kernels, in modern terminology) worked at 4 MHz and had 128 KB of RAM and 16 KB of permanent program memory. Such an architecture allowed the onboard computers to control the landing process of the Buran even in the conditions of a nuclear war (this was part of the TK at the request of the military).
For programming the landing process was chosen method of final approximation. In each work cycle, the onboard computer made a forecast that the ship would hit a given point depending on its current position, speed, state of the atmosphere on the landing route, and many other parameters, and if the forecast results diverged from the point needed for a successful landing, control commands were issued to adjust the trajectory. This cycle was repeated until the ship reached the final point of the landing stage.
A special PROL2 special problem-oriented real-time programming language was created and the SAPO programming and debugging automation system. The PROL2 language largely repeated the well-known logical language Prolog, but was built on the basis of Russian official words. Also, the Prolog-Dispatcher operating system was written on Prolog, which controlled the work of the onboard computers.
For testing of the Burana system and the ship as a whole, numerical modeling of all phases of flight was carried out, numerous ground stands were built and several BTS analogue planes were built.
The analog aircraft was a Burana glider with aircraft-mounted turbojet engines installed in the tail area. He could independently take off from the airfield and sit on it, both with the use of thrust engines, and in the planning flight.
After testing the system of automatic landing of the ship on mathematical models, it was the turn of full-scale experiments. They looked like this: the pilot raised the analogue aircraft to the maximum height, transferred it to horizontal flight and turned off the engines, and the engineers and programmers of the onboard computer could see in real time how the onboard systems control the landing process in order to correct the algorithm. Of course, it was a somewhat exciting moment, but everything went smoothly and, according to the results of a series of tests, the software-hardware complex of the automatic landing was allowed to fly. A total of 24 flights of the analogue aircraft were made ( www.buran.ru/htm/hrono.htm )
The first and only flight of the ship "Buran" took place on November 15, 1988. The landing took place completely in automatic mode, all the systems of the ship and the ground part of the Vympel automatic landing system worked normally.
Not done, however, without a curious case. The Buran was approaching the airfield somewhat to the right of the runway axis, and it all went to the fact that it would “dissipate” the rest of the energy on the southeast approach. So thought the experts and test pilots who were on duty at the joint command and control center. However, when entering the key point from a height of 20 km, the Buran “laid” a maneuver that shocked everyone in the command post. Instead of the expected landing approach from the southeast with the left roll, the ship was vigorously turned off to the left, and began to enter the runway from the north-east direction with a roll of 45º on the right wing.
Anton Stepanov, participant of the events described:
“ At the moment of the abrupt change of the Buran’s course, one of the female operators of our computers shouted“ Come back! ”- you had to see her face - he was immediately filled with fear, hope, and feelings for the ship as if it were his own child .
G.E. Lozino-Lozinsky:
" ... After Buran entered orbit, I saw with my own eyes how, in the Mission Control Center, a group of comrades prepared in advance the TASS Report that, due to such and such problems (they they were invented immediately) they failed to complete this experiment safely. These people came to life especially when, already approaching the landing, "Buran" suddenly began an unexpected maneuver ... "
Post-flight analysis showed that the probability of choosing such a trajectory was less than 3%, but under the circumstances, it was the right decision for the onboard computers of the ship.
At the moment, all copies of the Buran are lost, the entire reserve of the program has been destroyed. The ship that flew into space was mothballed until better times and completely destroyed when the roof collapsed in the hangar on Baikonur on February 12, 2005. The second flight of the ship continues to be at Baikonur in almost destroyed condition. The third ship was sold to a little-known company, Sia International, but was not removed to it and is located at the factory. The fourth and fifth dismantled at the plant for scrap.
By the way, the ship that stands in Gorky Park is not a spacecraft, it is a test aircraft analogue of the BTS.
Why is "And who do you work with?". Because I was lucky to work with a programmer of the Buran landing system, Alexander Y. Sundundov, for a year already. The article is inspired by his short-break stories.
What interesting people do you have lunch with? -)))
www.buran.ru
www.buran.ru/htm/vympel01.htm
www.buran.ru/htm/algoritm.htm
www.keldysh.ru/departments/dpt_23/dpt_23.html
www.xserver.ru/computer/langprogr/razn/16
Briefly about the program
A lot has been written about the “Energy - Buran” program, I would recommend to all who are interested to immediately go to the special website buran.ru , on which there is a lot of reliable information.To sum up briefly, the Energy-Buran program provided for the creation of a universal heavy launch vehicle Energia of the one-hundredth class and, as a payload for it, the orbital reusable spacecraft Buran.
')
The Buran ship was in many ways analogous to the American Space Shuttle system: a winged and tailless glider, tiled thermal protection, a cargo hatch, similar mass-dimensional parameters (output 30 tons and return from orbit 20 tons of cargo, crew up to 7 cosmonauts), but because equipment does not stand still, and our ship was developed later, and had significant differences. The Buran, unlike the American counterpart, was originally intended for docking with orbital stations and other ships, had a crew rescue system (its absence destroyed the crew of the Challenger at one time), and, most importantly, could perform the tasks of entering space , work in orbit and landing in fully automatic mode.
How did the Buran sit
Let us leave outside the scope of this article the stages of take-off, entering orbit and maneuvering, docking and working with a payload. Consider more landing.
As the writer Lukyanenko once aptly noted in the book “Stars - Cold Toys”, the landing of the Buran is performed with the “grace of a falling iron iron.” In this ironic phrase, of course, there is a sense.
In general, the landing of an orbital cruise ship can be divided into four stages:
- Descent from orbit
- Damping of orbital velocity in the atmosphere
- Maneuvering to enter the lane
- Landing on the lane
The descent from orbit is performed quite simply - the ship turns into a “tail forward, back to back” position, the cruise engines give an impulse that reduces speed below the orbital threshold, and the ship begins to go out of orbit. The engines of orientation at the time of entry into any dense layers of the atmosphere, and in our case this occurred at an altitude of about 100 kilometers above South America, turn the ship into the correct “airplane” position. From the moment of entry into the atmosphere until the moment of landing it takes about 30 minutes, during this time the ship must completely cancel the orbital speed (about 8 km / s), reach the specified landing area and land on the runway.
The task of the next stage is to reach a given point in the vicinity of the landing aerodrome with a given speed and orientation. The task is complicated by several points: firstly, the ship flies in a cloud of plasma most of the time and does not have the ability to communicate with the ground, secondly, by the time aerodynamic deceleration in the atmosphere begins, fuel for the cruise engine is already developed, therefore the speed increase maneuver is not possible when detecting undershoot Only the ship's glider can be controlled with the help of low-thrust and elevon steering engines.
Figuratively speaking, in order to quench the excess speed during the flight, the control system should slightly nose up, the aerodynamic drag will increase and the speed will decrease, and to compensate for the undershoot - on the contrary, lower the nose. This, of course, is a very rough approximation, but in fact it is correct.
The outcome of the second stage should be an exit to a point in the vicinity of the landing airfield at an altitude of about 4 kilometers and at a speed slightly above 300 km / h. At a higher speed, the Buran will be too inertial and will not be able to perform the maneuvers necessary for landing, and at a lower speed, it will simply fall into an uncontrolled dive due to its low aerodynamic quality (“falling iron iron with wings”).
Then comes the most difficult stage of landing - the exit on the runway. Automation, using ship sensors, readings of beacons and the flow of information from the ground control center, must understand where the ship is currently located, assess the strength and direction of the wind in the landing area, decide from which end of the runway to land and enter the lane. A speed error of no more than 20 km / h was allowed, a runway error of no more than 700 meters, a lateral deviation of no more than 38 meters.
Hard 'n' Soft
To control the landing process, in addition to ground-based monitoring and control, we used our own on-board digital computer (On-board digital computer) Burana Beads-4. The military order determined the architecture of the onboard computer - it was implemented as four parallel independent computing channels and a comparator, which continuously compared the results at the output of the channels. In case of deviation of the results of any of the channels from the other three, it was turned off and the on-board computer continued to operate in the normal mode. In the same way, another damaged computational channel could be disabled, thus achieving automatic backup and fault tolerance of the on-board computer. Computing channels (or kernels, in modern terminology) worked at 4 MHz and had 128 KB of RAM and 16 KB of permanent program memory. Such an architecture allowed the onboard computers to control the landing process of the Buran even in the conditions of a nuclear war (this was part of the TK at the request of the military).
For programming the landing process was chosen method of final approximation. In each work cycle, the onboard computer made a forecast that the ship would hit a given point depending on its current position, speed, state of the atmosphere on the landing route, and many other parameters, and if the forecast results diverged from the point needed for a successful landing, control commands were issued to adjust the trajectory. This cycle was repeated until the ship reached the final point of the landing stage.
A special PROL2 special problem-oriented real-time programming language was created and the SAPO programming and debugging automation system. The PROL2 language largely repeated the well-known logical language Prolog, but was built on the basis of Russian official words. Also, the Prolog-Dispatcher operating system was written on Prolog, which controlled the work of the onboard computers.
Tests and flight
For testing of the Burana system and the ship as a whole, numerical modeling of all phases of flight was carried out, numerous ground stands were built and several BTS analogue planes were built.
The analog aircraft was a Burana glider with aircraft-mounted turbojet engines installed in the tail area. He could independently take off from the airfield and sit on it, both with the use of thrust engines, and in the planning flight.
After testing the system of automatic landing of the ship on mathematical models, it was the turn of full-scale experiments. They looked like this: the pilot raised the analogue aircraft to the maximum height, transferred it to horizontal flight and turned off the engines, and the engineers and programmers of the onboard computer could see in real time how the onboard systems control the landing process in order to correct the algorithm. Of course, it was a somewhat exciting moment, but everything went smoothly and, according to the results of a series of tests, the software-hardware complex of the automatic landing was allowed to fly. A total of 24 flights of the analogue aircraft were made ( www.buran.ru/htm/hrono.htm )
The first and only flight of the ship "Buran" took place on November 15, 1988. The landing took place completely in automatic mode, all the systems of the ship and the ground part of the Vympel automatic landing system worked normally.
Not done, however, without a curious case. The Buran was approaching the airfield somewhat to the right of the runway axis, and it all went to the fact that it would “dissipate” the rest of the energy on the southeast approach. So thought the experts and test pilots who were on duty at the joint command and control center. However, when entering the key point from a height of 20 km, the Buran “laid” a maneuver that shocked everyone in the command post. Instead of the expected landing approach from the southeast with the left roll, the ship was vigorously turned off to the left, and began to enter the runway from the north-east direction with a roll of 45º on the right wing.
Anton Stepanov, participant of the events described:
“ At the moment of the abrupt change of the Buran’s course, one of the female operators of our computers shouted“ Come back! ”- you had to see her face - he was immediately filled with fear, hope, and feelings for the ship as if it were his own child .
G.E. Lozino-Lozinsky:
" ... After Buran entered orbit, I saw with my own eyes how, in the Mission Control Center, a group of comrades prepared in advance the TASS Report that, due to such and such problems (they they were invented immediately) they failed to complete this experiment safely. These people came to life especially when, already approaching the landing, "Buran" suddenly began an unexpected maneuver ... "
Post-flight analysis showed that the probability of choosing such a trajectory was less than 3%, but under the circumstances, it was the right decision for the onboard computers of the ship.
Results
At the moment, all copies of the Buran are lost, the entire reserve of the program has been destroyed. The ship that flew into space was mothballed until better times and completely destroyed when the roof collapsed in the hangar on Baikonur on February 12, 2005. The second flight of the ship continues to be at Baikonur in almost destroyed condition. The third ship was sold to a little-known company, Sia International, but was not removed to it and is located at the factory. The fourth and fifth dismantled at the plant for scrap.
By the way, the ship that stands in Gorky Park is not a spacecraft, it is a test aircraft analogue of the BTS.
About the second part of the header
Why is "And who do you work with?". Because I was lucky to work with a programmer of the Buran landing system, Alexander Y. Sundundov, for a year already. The article is inspired by his short-break stories.
What interesting people do you have lunch with? -)))
Links
www.buran.ru
www.buran.ru/htm/vympel01.htm
www.buran.ru/htm/algoritm.htm
www.keldysh.ru/departments/dpt_23/dpt_23.html
www.xserver.ru/computer/langprogr/razn/16
Source: https://habr.com/ru/post/86876/
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