BURAN Orbital

Spaceship Airframe

Creation

Maintenance Electromagnetic Compatibility of BURAN

Orbital Spaceship Equipment

Kornilov V.A.
Specific features and main directions of solution of a problem of electromagnetic compatibility (EMC) of BURAN Orbiter are surveyed. The contents of the accomplished works on EMC maintenance are explained. The tests’ results are shown.

Specific features of BURAN Orbiter as contrasted to by other flying vehicles including airplanes, were a considerably high-level provision with radio electronic and electric equipment and flight accomplishment, returning from orbit and airfield landing in an automatic mode. Therefore, the indispensable condition of successful implementation these operations would be an absence of failures in the equipment operation due to ‘unsuccessful’ EMC. Orbiter is equipped with an intricate complex of onboard systems including the control system with digital computers, various radio devices, system of onboard measurements, electric power supply system, distribution and commutation system. Other major systems of Orbiter and its airframe incorporate electronic devices with a large scope of backup, which together with the Control System (CS) perform functions of monitoring, diagnostics and control: Orbital Maneuvering System (OMS), Auxiliary Power Unit (APU), Hydraulic System (HS), system of thermal mode maintenance and others.

More than 1000 devices, about 40 different antennas, more than 1800 bundles are located onboard the Orbiter. Considering all this, the problem of EMC maintenance of onboard equipment has an important place in engineering process and tests of all Orbiter components, in particular of the airframe and its systems. Two basic aspects of the problem of EMC maintenance took place:

• electric power compatibility, i.e. compatibility by parameters and quality of power supply with allowance for all electric power consumers operation;
• the electromagnetic compatibility itself in view of the effect of intersystem and exogenous electromagnetic disturbances, and resistance to electromagnetic impulses from lightning and static electricity.

Meeting the Requirements on Electromagnetic Compatibility Maintenance

The specificity of works on equipment EMC maintenance of BURAN Orbiter was the task of thorough and unconditional performance of the appropriate requirements at all stages of creation of devices, systems and Orbiter as a whole. Thus it is possible to select the following directions of a solution of a problem EMC:

• development of the unified requirements to equipment;
• creation of laboratory-stand base;
• theoretical analysis of separate aspects EMC;
• tests of equipment and airframe.

Brief review of works accomplished in these directions is given below.

The unified requirements to the equipment for EMC parameters were formulated in Technical Conditions (TC) for BURAN Orbiter. These TC were developed by NPO ENERGIA in view of experience of creation and maintenance of flying vehicles (space and aircraft). Tolerance levels of disturbances created and perceived by the equipment were included in the Technical Conditions. On the basis of TC the appropriate requirements were introduced into the individual technical specifications.

The laboratory for organization, coordination and control of works on EMC and testing was created at NPO MOLNIYA and provided with the necessary test equipment including anechoic chambers. This ensured testing with use of modern means of automation at registration of results.

Special Technical Conditions of bonding were developed to comply with the requirements to EMC and in purpose of implementation of the integrated and monitored process of their maintenance, and TC and instructions on bundles manufacturing and mounting include the requirements on EMC. For decreasing interference attention was focused on:

• schemes of wires spin;
• optimum use of different types of screening;
• rational arrangement of screens grounding;
• screens continuousness provision and choice of the most efficient way of their tipping;
• selection of optimum arrangement of control, signal, power circuits and circuits with increased interference level in the cable bundles;
• bundles separate laying so that the electromagnetic contours were isolated as much as possible.

In the process of Orbiter airframe construction, electrical circuits, systems and devices development, and layout of components, EMC estimation and supervision of the requirements observance were permanently conducted.

At development of Orbiter electrical circuits the problems of grounding, screening and insulation, as well as requirement of reaching the ‘favorable’ compatibility of power supply circuits were most closely considered. With the purpose of guaranteed reduction of mutual interference of power supply circuits filters units were introduced into the scheme of distribution and commutation system.

In order to reduce the level of disturbances caused by static electricity draining from Orbiter body the development and manufacturing of non-conventional dischargers was required, which could operate under conditions of high temperatures.

The analysis of created by radio-emitting equipment electromagnetic fields influence on receiving devices was carried out. As a result, the optimum arrangement of antennas (more than 40) radio-emitting and radio-receiving equipment was determined.

For estimation of the induced by electromagnetic impulses of lightning in the cable network voltage influence on electronic equipment operation, the calculation of their levels was performed based on the techniques of Flight Research Institute (LII) was conducted. By the results of such estimation, the measures on influence reduction were taken in some cases. Further on the experimental obtaining parameters of the induced voltage was supposed during the tests on base of LII on the specially prepared for this purpose Orbiter analogue.

The documentation developed at NPO MOLNIYA and allied enterprises were submitted for experts’ study at the laboratory of EMC and coordination with the laboratory of bonding. The same laboratories conducted the supervision of the appropriate requirements observance in the process of manufacturing systems and the airframe with drawing-up the protocols and acts certifying quality of the executed works.

Special Tests

Special tests were conducted with the purpose of verification of the equipment conformity to the requirements for EMC including:

• independent tests of separate devices and systems;
• independent and complex within the structure of the full-scale stand of equipment;
• complex tests within the structure of Orbiter’s Analogue (BTS-002 vehicle);
• equipment tests on CS-003 complex stand.

The independent tests were conducted by enterprises-developers of equipment before its installation on the airframe with drawing-up a conclusion on its suitability for electromagnetic compatibility.

The final conclusion on EMC was received by the results of complex tests on 002 Analogue and CS-003 complex stand. Due to measures on EMC provision taken at development and manufacturing of the equipment and the airframe as a whole, the results of complex tests confirmed the compatibility of the equipment at all stages of operation.

The works on EMC and protection against atmospheric electricity were conducted under the technical direction of Mr.: Savin P.A. and Kovalev V.I. The main testers were Mr.: Kondrashov V.P., Golovatenko V.N., Kornoukhov I.N., Polenov S.P. and others.

Conclusions

The results of the works conducted by NPO MOLNIYA on provision of BURAN Orbiter airframe equipment EMC allow the following conclusions:

• it is expedient to analyze the materials obtained at EMC working-out, and to create the documents in the form of manuals or techniques on their base;
• application in the design of flying vehicles made of nonmetallic materials will demand the development of new requirements on EMC and protection against atmospheric electricity and plasma;
• the obtained experience may be used at creation of other flying vehicles, in particular, the advanced Aerospace Transport Systems.

Reference

1. L.L. Kerber. Equipment Layout of Airplanes. Moscow, MASHINOSTROENIE, 1976.
2. S.A. Erickson. Prognosis of Electromagnetic Environment Onboard the Spacecraft. Rockwell International.