BURAN Orbital

Spaceship Airframe

Creation

Orbiter’s Guidance and Control

Dr. Trufakin V.A.
Some problems of dynamics of flight and control synthesis for the Orbiter, arisen during work on Aerospace theme in a part of stability, controllability and manual control, are considered. The paper presents a brief description of methods and ways of the decision. Methodological and practical importance of results is evaluated.

The cases that are studied have defined the principled structure of the Orbiter’s control system on an atmospheric flight stage. At the same time they don’t exhaust all the problems on the specified subjects and reflect only author industrial and scientific sphere interests when working on SPIRAL and BURAN projects (1966 –1995 years).

When developing and solving these problems Dr. Studnev R.V., Prof. Yaroshevsky V.A., Dr. Kobzev V.I. (TsAGI), Dr. Puchkov A.M. (MARS Design Bureau) and Dr. Samsonov E.A. (NPO MOLNIYA) made a great contribution.

It is necessary to mention the large role in design, stand and full-scale researches on the specified questions of Dr. Gorbatenko V.V., Mr. Gorbunov N.I., Karlin V.S., Dr. Volodin V.D., Mr. Sviridenko A.N., Dr. Dudar E.N. (NPO MOLNIYA), Dr. Bushgens A.G. (TsAGI), Dr. Ezova T.A. (LII) and others.

Test pilots Volk I.P. (LII) and Bachurin I.I. (GNIKI VVS) took part in researches connected to improvement of manual control.

Stability and controllability problems

When forming the Orbiter’s stability and controllability maintenance system its characteristic features, stipulated by presence of a heat protection, large wing leading-edges’ and fuselage radiuses and profile thick trailing edges, are taken into account. The following factors are also taken into consideration:

• presence of non-linearity in control loop and probability of the ‘in large’ instability appearance;
• probability of oscillations appearance, induced by the pilot;
• large reserves of stability in roll lateral channel and their essential relation from the angle of attack, causing strong roll motion and yawing interaction;
• inverse roll response presence on lateral control devices deviation;
• necessity in high control efficiency in required vigorous maneuvering and technical constraints on actuators (drives) conditions. These features have defined the necessity in special researches and unconventional engineering solutions.

Longitudinal Stability ‘In Large’

The presence of constraints on the rate of control devices’ displacement may result in unstable limiting cycle of oscillations. This cycle is illustrated on a phase plane, showing relation in changing angle of attack (α) and pitch angular rate (ωz) in longitudinal motion of Orbiter. The exit out the cycle’s boundaries results in the irreversible Orbiter’s swing and its loss because of its destruction or stalling (stability loss ‘in large’ mode).

For the orbiters, having small reserves of longitudinal stability and the drives’ limited fast-track characteristics, the problem of stability ‘in large’ notably becomes aggravated under certain conditions. Use of remote control systems also promotes the same, because in these systems (at the given stage) the control handle moving speed has no mechanical restrictions.

The consideration of the own and forced oscillations’ structures in a manual control loop for longitudinal motion has shown the probability of stability loss ‘in large’. The flight phases at subsonic speeds with small dynamic pressure are the most critical (q < 1000 kg/square meter).

Let’s mark, that the problem of stability maintenance ‘in large’ breaks up on two:

• maintenance of wind stability;
• maintenance of stability on control action from the pilot.

The latter, as a rule, is more critical and requires acceptance of special engineering solutions.

The probability of Orbiter’s instability ‘in large’ for the first time was detected in the stand study on abnormal situations (failure in the hydraulic systems’ separate channels) at manual control on Full Scale Stand of Equipment (FSSE). As a result of these researches the cause and conditions of instability ‘in large’ origin were determined.

As a means for required longitudinal stability and enough controllability, the Self-Adapting Filter (SAF) was developed and introduced into a control loop. The filter executes speed restriction on an input signal, so that a general signal from control handle (or from the trajectory control system) and pitch damper doesn’t not result in excess of maximum acceptable speed values in front of the drive [1]. Such solution provides an absolute stability on input signal.

The designed recommendations on stability problem were realized in onboard software, verified at stand and flight tests and were positively estimated by pilot’s staff. The SAF using is expedient for a broad class of flying vehicles. On its base the development of alternative devices, eliminating stability loss in longitudinal channel, is possible.

Stability of the Closed-Loop System, Including Pilot in a Control Loop

The analysis of the closed-loop system’s stability with the pilot in a control loop has been fulfilled. It has shown behavior of Orbiter of tailless (‘Delta’ wing) aerodynamic configuration in the case of digital computer application to the control problem. In this case the equivalent dynamic lagging (delay) in the longitudinal channel (in the circuit ‘control handle position Xh → pitch angle speed ωz’) becomes much more, than for flying vehicles of the conventional scheme. Thus the stability and controllability characteristics’ maintenance appears to be insufficient even at the first level of the requirements. It is because the requirements are formed in the terms of classical parameters of transients (response time, g-load hardover etc.) and actually meet a mode of the programmed open-loop control (impulses, relaying and ration).

The flight tests’ results and obtained amplitude phase frequency characteristics (APFC) in the ‘Xh → ωz’ channel has shown the probability of increase in the pilot’ gain and in the frequency of stabilization, which may results in exit trough the ‘Orbiter – Pilot) systems’ limits of stability. These phenomenon, caused by specific features of the Orbiter’s flight conditions (unpowered trajectory), in particular, have took place in some flights of the BURAN full-scale Analogue [2].

The transition from automatic to manual control at the first flattening-out process was the most critical from the point of view oscillations, induced by the pilot. For this reason the recommendations were formulated, according to which the transition to manual control is expedient at normal g-load of 1,01 (at the altitudes of H > 350 m).

The essential increase in ‘comfort’ of transition from automatic to manual control may be ensured by algorithmic means. That is why the algorithm of ‘soft writing off’ was developed and recommended to introduction. The real expansion of stability margins of the closed-loop ‘Orbiter - Pilot’ system at operational frequencies (of ωz ≤ 4 sec−1) may be reached by APFS improvement of the ‘Xh → ωz’ channel.

Now the problem of stability in the closed-loop ‘Orbiter - Pilot’ channel is actual enough and requires additional researches.

Features of Orbiter’s Lateral Motion at Landing Stage

The study on dynamics of flight of the small-scale orbiters (of 5 - 15 tons weight) at subsonic velocities has shown necessity of estimation for lateral stability of the orbiter’s roll response on wind disturbances. The study has been made for the SPIRAL orbiter in hypersonic configuration with the wing console, inclined by 45° angle. It has been shown high frequencies of orbiter’s own lateral oscillations and large reserves of lateral stability. It is especially important for the landing stage, where the mentioned case may become the reference for selection of drives’ speed of response, estimation of permissible cross wind or it may determine introduction of additional controls and vehicle configuration change [3].

The lateral motion stability (in classical understanding) is examined on the basis of linearized equations of lateral motion, obtained by flying vehicle full (3-D) motion equations dividing on longitudinal and lateral motion. The stability of lateral motion in such statement does not depend on value of the disturbance. In real motion, because of probable non-linearity in the longitudinal and lateral motions’ interaction, the stability of lateral motion is determined, under other conditions, also by the level of disturbances: lateral gusts and short-time disturbance in yawing moments. As to the latter case, similar picture may at rudder’s deviation by the pilot, or at failure in automatic control in yawing channel.

Analyzing the accident, caused by the loss of stability and controllability, of one of the first foreign analogue (American M2-F2 experimental flying vehicle) during the landing approach, we can see the real probability of sufficient longitudinal and lateral motions’ interaction.

In order to estimate the specified factors’ influence on the Orbiter’s dynamics, the technique and conditions for studying the inertial interaction’s effect on rolling motion were developed. The limiting values of disturbances, determining stability in lateral motion, were also obtained [4].

The realization of the specified estimations at initial stage of the Orbiter’s designing is obviously necessary. The developed technique may have application to flying vehicles of other schemes.

Orbiter Inverted Lateral Control

One of the Orbiter’s features is the change of roll response from a direct on an inverse at lateral control devices’ deviation, depending on the flight angle of attack (α), Mach number (M > 2-3) and aerodynamic configuration of the vehicle. In this case habitual relation between a deviation’s sign of lateral control device and angular acceleration is broken, (+ δ aileron → + ω roll), i.e. to positive control displacement there corresponds positive angular acceleration, that does not allow synthesizing usual (in aircraft understanding) system of direct lateral control at the specified conditions.

During design studies the different ways of ensuring the Orbiter’s direct reaction on lateral control devices’ deviation were considered:

• introduction of the interaction between longitudinal and roll controls, adjustable on an angle of attack;
• introduction of the rotation axis’s negative sweep for the roll control devices;
• introduction of special controls (upper spoilers) for the legs of trajectory, where is the occurrence of opposite reaction in Orbiter’s roll motion;
• an inclined wing console application to the control in roll channel.

The specified directions were not effective. At the end the new way of lateral control was developed (Inverted Roll Control) and recommended for these conditions of flight. The method uses the opposite reaction in roll motion on lateral control devices’ deviation and keeps all external properties of usual (as in usual aircraft) roll control [5, 6].

The essence of the offered method for lateral control is that roll stability moments may be used through a slip angle. The inverted lateral control may be realized both in manual and in automatic control modes. At inverted manual control the problem of stability maintenance should be decided automatically with the use of oscillation’s dampers.

The motion in yaw channel does not appear at the inverted control, because slip stabilization is done in roll channel, i.e. the slip angle (β) is a constrained parameter. For this reason the inverted control can not be used at landing stage, because the cross-longitudinal balancing at cross wind is not provided.

The designed way of control is protected by the copyright certificates and is realized on the Orbiter. It is necessary to mention that there is mot now an alternative way of lateral control on a hypersonic flight stage M > 3-4.

Mixed Aero- and Gas- dynamic Control and the Principle of Non-Deficit Control

The Orbiter pre-landing approach stage (at the altitudes of 10 km ≤ H ≤ 20 km) requires high control efficiency. First of all it is connected with necessity of vigorous maneuvering in the conditions of quick lowering dynamic responses in a combined (rudder - air break) control system, which may lead to disconnection in the loop of aerodynamic control.

The rational solution for efficiency increase in rolling-yawing control is offered to expand the leg of Reaction Control System (RCS) engines’ application in the yawing channel, when forecasting Aerodynamic Control (ADC) shortage in conditions of large disturbances.

The main purpose for synthesis of the RCS loop is to detect a correct set of Control Engines’ (CE) ignition and cut-off. The base for this is the estimation of the lateral g-load loop phase and dynamic state. This has defined use as initial in RCS channel a command signal, formed in AC loop for the rudder.

During structural synthesis of aero- and gas- dynamic control the schemes of channels were developed:

• the RCS with the most self-sufficiency in relation to ADC channel;
• estimations of current phase state vector in lateral g-load loop;
• the RCS residual control low signals transmission to ADC by engines’ time in use integral estimation.

The RCS loop dynamic synthesis on the base of specially developed models was conducted, including the following:

• regulation processes’ estimations ‘in small’ (linear model on the basis of quasi-linearity hypothesis);
• stability study ‘in large’ (hereinafter non-linear models);
• definition of constraints on the phase coordinates’ motion;
• estimations and correction of the periodic processes’ parameters.

The efficiency of the synthesized aerodynamic contour is confirmed by methods of mathematical simulation. The developed schemes have no industrial analogues, are protected by the copyright certificates and are realized on the Orbiter [7, 8].

The aero- and gas- dynamic control’s analysis and synthesis became the beginning general questions of sufficiency researches or control non-deficit from positions of necessary effects improvement in conditions of really limited capabilities of actuating devices [9].

The basis of the approach is made and entered into consideration by the dynamic analysis of differential equations’ right member, describing motion of the object for an integral estimation of required and available controls.

The terms of the control deficit are introduced:

• on a level of control function;
• on a rate of control function change;
• on stability ‘in small’ and ‘in large’.

The sufficient conditions and control non- deficit criteria in structural realization of the mixed multi-component control are offered in view of an optimal work of RCS and ADC components on the basis of adjacent channels necessities, fuel use and control non-deficit. On the basis of the explained approach the development of technique and software maintenance of non-deficit control estimation is planned at improvement of the disturbance factors for objects of a general view.

The Principles of Manual Control

For domestic orbiters of nowadays, three control modes on an atmospheric flight stage are determined: they are automatic, director and manual. The automatic and director modes are provided at all stages of the flight from the moment of de-orbit and till the landing. The manual control mode application was stipulated from an altitude of 20-30 km till landing on runway. The materials below display the necessity of conditions application refinement of different kinds of control (manual, director) and allow formulating some principles of manual control systems construction of the nearest future.

Director Control Mode

The system of director control uses command signals, formed by an automatic system of trajectory control. The specified signals move on command arrows of Control-Piloting Device (CPD) through the definite algorithm, realized in the computer to map to the pilot in order he could make a decision. Such construction of the director control system is a traditional one and is used in modern aviation.

It is necessary to say that for the director system (DC) on a flight stage H > 20 km in formation of control signals on CPD rods, closed loop on control actions from command control devices can be introduced.

The stand researches of motion in director control mode, constructed on conventional principles of CPD use, have shown that the approach and landing is provided. However this mode for the pilot is operation of simple compensatory tracking, which is not using his abilities. Fulfillment by the pilot monotone uniform operations during the all long descent stage (more than 30 minutes) at the absence of situation’s prognosis does not give the pilot the necessary psychological comfort [10].

The effective actuation of the pilot into control procedure is possible if providing the pilot with complex information about possibility of Orbiter’s guiding to the given area (besides the information from a director system).

It is necessary to mention that the director control in modern aviation, as a rule, is used for control on most critical stages of flight, requiring high accuracy of the piloting without significant maneuvers and short-lived in relation to general flight time (landing approach, landing, extreme-low-altitude flight etc.). The results of researches have shown that use of director control mode on descent stages and pre-landing approach maneuvering is hardly expedient. The director control can be recommended both in lateral and longitudinal channels on a final stage of the flight at altitudes H < 4 km, when landing in conditions of restricted visibility in the runway region.

Use of Manual Control Mode

In 1981 – 1982 years the classification of manual control mode was presented, depending on data support of the crew (see information below). Many studies on manual control (HOC) allowed forming the requirements to data support of the crew necessary for manual piloting, to Automatic Control Mode (ACM) and to decision about transition from ACM to HOC.

The requirements include the following:

• Orbiter’s current state and permissible boundaries of motion;
• the boundaries of available mechanical energy corridor;
• the integrated information about the predictable finish Orbiter’s position;
• the prognosis on mechanical energy reserve as a miss-altitude (concerning the fixed point) or distance along the shortest trajectory.

The specified requirements have allowed to update definition of manual control mode that has put the end to numerous explanations of the modes:

‘The manual control mode for the center of mass motion trajectory is a mode, at which mission plan, formation of trajectory and its realization implements directly by the crew through command levers on the basis of the specialized integrated information on the predictable finishing position of the Orbiter and its current state, concerning the available and permissible boundaries of the energy corridor, traditional flight-navigational information, the visual analysis of an outside world and information from the Earth’ [10].

Depending on the volume, kind and structure of data support of the crew three levels of manual control are considered:

• ft full information;
• at minimum data support;
• at interaction with a ground control post.

When these manual control modes, the pilot uses the appropriate information, presented to him on special display as a complex information pictures, or normal flight-navigation information with the use of voice commands from the Earth or without them.

Manual Control at Full Data Support of the Crew

When choosing the strategy of manual control for H > 20 km the information model, based on the Orbiter placement inside energy corridor in coordinates ‘mechanical energy E (V) – the rest distance to destination Lrest’ and heading angle Δψ, concerning the terminal point of guidance, was used. The available energy corridor is determined by flight stages on the shortest and the longest (but not skip) trajectories. The value of the rest range Lrest is determined along a great Earth circle from the current Orbiter’s position up to the point of destination and Δψ - as an angle between velocity vector and specified great circle plane.

The strategy of manual control in this case is reduced to realizing Orbiter motion inside the energy corridor on as much as possible greater removal from its boundaries with maintenance of controllability in a horizontal plane. Other possible way of control on trajectory motion may be the use of variable ‘longitudinal g-load nx - speed V’ that simultaneously allow to inspect the temperature constraints, drag and normal g-load, as they are easily transformed to constraints on longitudinal g-load in fast-track coordinate system.

In the specified coordinates ‘nx - V’ the lines of equal available distance nx = f (V, Lav), determining at any moment available range (Lav) from the current state up to a point of destination, may be constructed.

The control of longitudinal trajectory motion can be done with the use of the specified information. Having the information on the rest distance Lrest, at manual control the pilot has to ensure equality of available and rest distances Lav = Lrest by roll angle change (and in some cases by angle of attack change) Lav = Lrest [11].

The stand researches, carried out on the base of two developed informational pictures, have defined the most acceptable compromise way, using the following coordinates:

• for the upper descent leg (H = 100-45 km) - coordinates ‘nx - V’;
• for the lower descent leg (H = 45-20 km) - coordinates ‘E – Lrest’.

The results of stand researches on manual control at designed data support and technique of control have shown that the accuracy of Orbiter navigating into final area at the altitude H = 20 km is not worse than: ΔL = ±13 km, ΔV = ±40 m/s, Δψ = ±15°.

For formation of the manual control strategy (H < 20 km) the prognosis of the altitude schedule along horizontal track of shortest or nominal trajectories is done, the information about which delivers to the automatic system of trajectory control (Guidance system). Simultaneously on this basis the algorithms of the additional prognosis (irrespective of main Guidance system) evaluate terminal miss on the altitude for the nominal and the flight trajectories [12]. At formation of informational picture the above-stated misses on the altitude were one of the key elements. The pilot does formation and realization of the trajectory in a lateral channel by stabilization relatively nominal and shortest track. In a longitudinal channel the stabilization of the given required altitude is reached by the item reduce to zero of terminal miss on the altitude at holding the current angle of attack and required speed within the framework of the given constraints.

The stand simulation has shown that the designed informational pictures provide the Orbiter navigating in manual mode with accuracy on the altitude and deflection in the key point (H = 4 km) not worse than ± 500 m.

The obtained results are realized as the requirement specification on onboard programming of onboard data support for the purposes of manual control.

Manual Control at Minimum Data Using Commands from the Ground

The mentioned levels of manual control are considered as abnormal modes for using in emergency situations for altitudes H < 30-20 km. This mode at minimum data support is founded on the information obtained with traditional aircraft equipment. The essence of this control mode is the approximated estimation by the crew of the Orbiter’s current energy state.

The formation of a required trajectory is made by selection of appropriate trajectory leg and maneuver, depending on the predictable final energy condition [13].

The results have shown enough accuracy for had-operated navigating from any point of all the permissible states’ area. The available informational pictures provide possibility to the crew to make inspection of automatic system’s operation. The manual control, using interaction with a ground control post, consists of flight trajectory prognosis on on the base of external trajectory measurements, producing appropriate commands and their voice transmission to the crew. The developed algorithms of prognosis and the informational pictures provide reliable and effective enough ground-command control for the navigation officer [14].

Information Displaying System and Automatic Control Systems Functional Relationship

The formation of data support in view of the formulated requirements (hand control with the full information) requires special software and one of most important is the question of this software interference with the software of automatic control mode.

The majority of the information, necessary for map on displays with the purposes of hand control, is formed in the required kind by algorithms of automatic control (first of all in the part of the motion prognosis). The missing information (in a part of the permissible energy corridor) requires additional evaluations and conversions. The principled rule about use of the information from automatic Guidance algorithm in the purposes of hand control for the first time was formulated in [15]. This approach is the most expedient and is justified on the following reasons:
1. Use at hand control the shortest or the nominal trajectories, formed by normal automatic control system provides compatibility of the hand and automatic modes.
2. The inspection of the automatic control is provided by display pictures; the decision about change to hand control is the progressing withdrawal of the Orbiter from a nominal trajectory and increase of deficit or predictable energy reserve with their approximation to limiting values.
3. The adopted principle of director control provides its compatibility with hand controlled devices.
4. The results of nominal automatic landing improvement, including, in particular, statistical modeling, are substantially transferred on a hand control mode with the use of display system.
5. The structural unity of algorithms eliminates control strategy ambiguity in hand and automatic modes; and this essentially improves reliability of the control and decision-making by Center of flight control.
6. The minimum of additional resources of the onboard digital computer is required because of the maximum use of nominal algorithmic software.

The aircrew also emphasizes the necessity in creation of the integrated automatic and manual control system’s, but based on the technique being the most acceptable for the pilots when the manual mode. The example of such approach may be the algorithm with continuous reference trajectory’s prognosis. That is why there is no concept of deflection from the planned trajectory of motion (after each prognosis the reference trajectory begins from the Orbiter’s current position). It allows the automatic and manual control modes to be integrated. For the first (automatic) version the reference trajectory forms the basis for development of command signals, and for the second (manual) version the reference trajectory serves as the supplementary information for the orbiter power capabilities estimation and its orientation concerning the runway and selection of the control strategy. Such approach meets the stereotype of the pilots and is more convenient for realization at manual control stages.

Autonomous Software for Manual Control

An alternative approach is to form the displaying information, based on the energy state prognosis being independent from the automatic Guidance system. Such approach practically results in the necessity of additional algorithms, functionally close to similar automatic algorithms and intended only for manual control.

The analysis of this approach shows the following [15]:

1. Alongside with the information, necessary for manual control, there should be on displays an appropriate information about operation of automatic system, describing the type of trajectory and ensuring adoption by the crew the decision about change from an automatic mode to a manual one.
2. The introduction of parallel algorithm into the main control system does not increase its software reliability. On the one hand, it is because in the complex integrated systems the criteria are not clear. On the other hand, at digital computer or software failure both the paralleled algorithms become disabled.
3. The compatibility of automatic, director and manual modes is provided only in case of compatibility of control algorithms for automatic and manual control; otherwise reciprocity of modes change from one to another is problematic.
4. The introduction of additional algorithms in software for manual control data support requires additional computing resources.

Thus, all the materials display that is most rational within the framework of the unified computing system to form software of manual and automatic control modes on the basis of unified algorithms, taking into account the priority of control mode when selecting the base algorithm.

Manual Control and Reserve Control Loop

In order to increase the Orbiter’s general reliability and safety, the capability of realization onboard the Reserve Control Loop (RCL) was considered. The general requirements to RCL we can formulate as follows [15]:

• actuation of the crew in the control loop and its effective use;
• algorithmic and software reserving;
• the independent inspection of the main control loop from the RCL;
• information displaying algorithms do not depend on the main loop.

When controlling the Orbiter by RCL, automatic or manual modes are possible. At the final stage of the flight the manual mode can be priority one.

The necessity of director control mode realization in RCL is being studied.

The change from main control loop to reserve one is made by crew. The criteria of the control mode’s change are indicated in the instruction to the crew and are provided with the necessary information on displays. The inverse change from the reserve loop on the main one is problematic.

When controlling by the reserve loop, the nominal displays of the information are used. The information on displays from RCL can be seen at any moment, including time interval of main control operation. The display information from the reserve loop should be compatible to the similar information from the main loop.

Display information development and formation in the reserve loop should be conducted on the basis of unified RCL algorithms; thus, besides computing resources economy, reaching the compatibility of automatic and hand control, at simultaneous possibility to inspect the automatic mode by the crew.

The requirement of display information compatibility on display for the main and the reserve control loops considerably should facilitate manual control and inspection of automatic mode.

Conclusions

1. One of the possible condition of the longitudinal control loop in ‘Orbiter - Pilot’ system is the mode of instability ‘in large’. The means of longitudinal stability support have been developed, they have been checked in stand and flight tests and have received a positive estimation from the aircrew and are realized in onboard software.
2. The Orbiter’s flight tests have confirmed estimated characteristics of stability and controllability. These tests have allowed to update some piloting questions and to give the necessary recommendations for control system development. Thus the necessity of multifold analysis of the closed-loop system characteristics with the pilot in the loop has been shown.
3. For small Orbiters the high response on disturbances in a roll channel is characteristic, that is why the inadmissible hardovers on bank angle at landing or development of instability modes stipulated by influence of inertia interaction between longitudinal and lateral motions are possible. 4. The way of longitudinal control (inverted control) grounded on the moments of lateral stability use for roll control has been developed, and the conditions of its use are determined. The alternative way of lateral control on a hypersonic flight stage now does not exist. The designed way of control is realized on the Orbiter.
5. On the base of the formulated principles and directions of structural and dynamic synthesis of the mixed aero- and gas- dynamic control has been developed. The developed methods are new ones and the structural constructions have no industrial analogues. The synthesized loop of the aerodynamic control is realized on the Orbiter.
6. The classification is introduced and the definition of manual control mode has been developed, capability and necessity of its use are justified and requirements to its interaction with automatic control mode.
7. Special requirements to data support for the manual control are developed, on the base of which the information pictures, ensuring the crew control and motion inspection and also compatibility with automatic mode, are formed. All that has defined the development of the instructions on manual control.
8. Manual control has also been developed at participation of the crew at minimum data support in the case of abnormal situations. The designed recommendations are included into the instruction on the Orbiter flight maintenance.
9. The methods of ground-command control have been offered on the base of external trajectory measurements with the use of a voice radio channel on the base of the following:

• the Orbiter’s condition prognosis;
• statistic (a priori) kinds of indication.

The recommendations on principles of ground control complexes construction and organization are adapted to realization for BURAN Orbiter and are reflected in the design and operational documentation.
10. The designed methods of manual trajectory control can be recommended for use for all flying vehicles for which the irreversible processes in dynamics of motion are characteristic ones.

Used Literature

1. Gorbatenko V.V., Trufakin V.A. Research on Longitudinal Stability at Manual Control of Aerospace Plane // Problems of Aerospace System Creation, issue 2. Questions of Manual Control. Moscow. NPO MOLNIYA, 1989.
2. Trufakin V.A., Ezova T.A., Bushgens A.G. Features of Manual Control in Angular Motion at Landing Stage (the results of flight tests). // Problems of Aerospace System Creation, issue 2. Questions of Manual Control. Moscow. NPO MOLNIYA, 1989.
3. Vinogradov U.A., Studnev R.V., Trufakin V.A. Some Features of Lateral-Direction Dynamics of Hypersonic Flying Vehicles at Subsonic Speeds // 2nd Conference on the Flight Dynamics. Moscow. TsAGI, 1971.
4. Studnev R.V., Trufakin V.A. Plane Motion Estimation at Large Roll Disturbances // Some Questions of the Plane Lateral Motion Theory. Moscow. TsAGI, issue 1399, 1972.
5. Studnev R.V., Trufakin V.A., Kobzev V.I. and others. Way of Flying Vehicle Lateral Control. Inventor’s certificate N. 56676. 30.06.1969.
6. Trufakin V.A., Kobzev V.I., Samsonov E.A. Lateral Control of Aerospace Plane at the Reference Roll Response on Control Device Displacement // Aircraft Engineering. 1985. N. 3.
7. Puchkov A.M., Trufakin V.A. Synthesis of Aero- and gas- Dynamic Control of Orbiter’s Lateral Motion for Automatic and Manual Modes // Problems of Aerospace System Creation, issue 2. Questions of Manual Control. Moscow. NPO MOLNIYA, 1989.
8. Puchkov A.M., Trufakin V.A. Control System and Stabilization of Orbiter’s Lateral Motion Inventor’s certificate N. 295261. 30.06.1988.
9. Puchkov A.M., Trufakin V.A. The Principe of Control Non-Deficit in the Automatic Control Theory and its Satisfaction Criterion. IAC'94 International Aerospace Congress. Moscow, Russia, August 15- 19, 1994.
10. Trufakin V.A., Volk I.P. Orbiter Manual Control Mode and Conditions of its Use. // Problems of Aerospace System Creation, issue 2. Questions of Manual Control. Moscow. NPO MOLNIYA, 1989. 11. Dudar E.N., Yaroshevsky V.A., Trufakin V.A. Control of Orbiter’s Trajectory at the Solution of Navigational Problem with Minimum Volume of Evaluations and Constructions of Manual Control Algorithm for the Descent Stage. // Dynamics of Flight and Orbiter’s Manual Control at Descent and Landing. Moscow. TsAGI, 1988.
12. Volodin V.D., Voskresensky A.V., Suprenenko S.N and others. Data Support of the Orbiter’s Crew when Manual Control of Pre-Landing Approach with Use of Onboard Displays // Aircraft Engineering. 1988. N. 2-3.
13. Trufakin V.A., Volk I.P., Belova E.U. Orbiter’s Manual Control at Minimum Data Support of the Crew // Problems of Aerospace System Creation, issue 2. Questions of Manual Control. Moscow. NPO MOLNIYA, 1989.
14. Sviridenko A.N., Trufakin V.A. Orbiter’s Manual Control at Interaction with a Ground Control Post // Problems of Aerospace System Creation, issue 2. Questions of Manual Control. Moscow. NPO MOLNIYA, 1989.
15. Trufakin V.A., Yaroshevsky V.A., Bushgens A.G. About the Principle of the Orbiter’s Automatic, Director Manual Control Modes Construction // Problems of Aerospace System Creation, issue 2. Questions of Manual Control. Moscow. NPO MOLNIYA, 1989.