by Gennady MALYSHEV, Dr. Sc. (Tech.), Moscow Aeronautical Institute
The current market of "space services" (mainly in telecommunications) now ranks first in terms of financial turnover, approaching 30 bin dollars a year. And experts expect this figure to double within the next 3 to 4 years. Naturally enough these "pastures of plenty" have all been shared by different monopolies which makes access to them by "ordinary" means practically impossible. One of them - altitude relay systems - will be far superior by their technical, economic and operational parameters and service life to any and all of the existing ground and orbital systems of this kind.
During the past few years experts in this and other countries have been busy working on relay stations operating at altitudes of 10 to 20 km. In order to deliver the equipment to these altitudes, and keep it there over long periods of time, specialists have been considering three possibilities: moored or captive balloons, free-flying airships and what are called barraging aircraft. But each of these alternatives, regrettably, has flaws of its own.
The first two possess a very low ratio between the external parameters and the payload they can lift into the rarified upper atmosphere. Some of the present- day projects of this kind use balloons and/or airships of thousands cubic meters in volume and measuring several hundreds of meters in size. And apart from their formidable aerodynamic drag, carriers of this kind will have to be brought back to earth at intervals of two to three weeks for their "refuelling" with helium, which is a very expensive operation (one ton of gas coats one min dollars).
As compared with the other versions, the use of barraging aircraft offers a number of advantages (such as greater maneuverability, versatility, etc.). But here again we run into the snag of high operational costs: one hour of flight of such aircraft costs several hundreds and sometimes even thousands of dollars.
But even despite all of the aforesaid drawbacks, relay networks of this kind are now being used in the United States and astern Europe. In view of their absence in Russia, our Institute has been charged with the task of producing tangible alternatives. After due consideration of such alternatives by our experts, one really unique solution of the problem has come to the surface.
The thing is that there exists a natural phenomenon by the name of tropospheric wind, which keeps blowing all the time at altitudes of 9-12 km at speeds of 15-25 m/s (depending on the time of the year, the coordinates over the earth surface and the global conditions of the atmosphere caused by solar activity and weather anomalies). Exhaustive information about this phenomenon has been at the disposal of experts over a number of years but they failed to put it to any practical applications. And now we have decided to fill this gap, so to say.
In our studies we proceeded from the assumption that in any concrete geographical region the velocity and direction of tropospheric wind remain practically constant all the time and the altitude at which this wind is blowing turns out to be quite acceptable. The idea was to design and build a flying "platform", attached to the Earth and hovering in the wind current at an altitude of about 10 km from the ground. Putting these dreams into practice has been promoted by the achievements of what we call low-speed aerodynamics combined with the development of super-light polymer cable systems and the advent of new non-metallic structural materials. The "trifles" which remain to be done included making use of all the "practical" scientific and technical achievements and designing the required type of a "flying platform".
It was clear right from the start that this "platform" had to be a sailplane, or glider, whose final shape and size remained undecided. After a long period of quests and calculations, our ultimate choice was a biplane, but of a very particular kind. Its small wings, controlling the flight, had to be positioned in front of the fuselage and the lift was to be produced by a box-shaped, or cellular, module. And, as in all biplanes, the latter consisted of two parallel wings (one- level with the fuselage, and the other above it) interconnected with four vertical fins, or stabilizers, with two of them being placed at the wings' ends, forming a closed contour.
And it may be appropriate to recall at this point that any winged system - from dragon-fly to a most advanced fighter plane - is characterized by a ratio of aerodynamic efficiency (lift-drag ratio) and wing loading. And for an aircraft and a glider the former parameters are 20 and 50 respectively, and the L/G factor - 120-200 kg/m 2 , our "brainchild" boasts the parameters of 30 and 5-10 kg/m 2 respectively So what we have got as a result is a flying machine which combines the properties and characteristics of a classical glider, motorized glider, a kite and a wing-parachute.
Thus the flying "base" of the required system was found. What remained to be done was to decide on its "mooring" to the earth and its elevation to a required altitude. For the former we decided to use advanced synthetic materials like Kevlar which is used for bullet-proof vests. And we were able to produce a "mooring line" of not more than 4.5 mm in diameter with a strength factor of 3. And its drag was comparable to that of the platform itself. As for launching the platform into the zone of tropospheric wind, we decided to run it up either along a straight or a spiral path, using either a towing truck or a tugboat.
In a word, our specialists have designed an aerodynamic towable lift-and- transport system of high aerodynamic parameters and low specific wing loading which makes it possible for the whole structure to perform dynamic soaring under the effect of mean statistical (by altitude) wind loads with towline fixation relative to the earth surface or the moving tug. A glider weighing 800 kg can lift a payload of 250 kg to an altitude of about 10 km and remain there for an unlimited length of time.
This new complex has been named an aerodynamic integral (or hierarchic) system of telecommunications - AIST (literally meaning stork). Now why is this so? The thing is that one unit of this kind can provide for TV, telephone and radio communications as well as data transmission (Internet, videoconferences etc.) within a large, but still a limited zone with a radius of about 100 km. And to provide a broader coverage with the same menu of services it would be necessary to have several such AISTs with one of them acting as the central link.
The next hierarchical unit of this system is a region - a set of geographical regions located codiderable distance away from one another. Data between them is transmitted by what we call zonal ground centers having the appropriate equipment and using cable or satellite communication. Further expansion of the system will provide for the establishment of inter-regional or global networks.
So what are the benefits AIST can offer us? Let us try and answer this question on the example of Moscow and the Moscow Region. Today broadcasts and telecasts there are transmitted by two high-altitude (Ostankino and Shukhov) towers and a thousand smaller towers of 70-80 m high. Using our new system for the same functions (their range is actually much broader, which I shall describe later on) it will be necessary to launch three such transmitters at a cost of only 4-5 percent of the present one. When the project was ready in its final form, it turned out that the actual potentialities of the proposed new system are far greater than we had expected. Apart from acting as a relay center with a broad radius of coverage, one single AIST can also be used for other applications, depending on its technical "filling".
For example, loading it up with optical devices operating in the visible and infrared regions of the spectrum it should be possible to control an area of 200 km 2 with a resolution of less than half a meter and on a real-time-scale, obtaining information on the conditions of buildings, roads, power transmission lines, heating networks and underground installations. AIST will help to pinpoint the breakdowns of various lines of communication, keep check on the losses of heat in industrial and residential units and maintain ecological monitoring of an urban center. Data collected in this way will help in the planning of new building sites, transport and engineering links and in drafting of what we call a geoinforma-tional map of a given region. And, finally, what seems to be an utterly fantastic idea - using AISTs as the basis of fire-prevention systems for tall and difficult-of-access structures using which it should be possible to put out fires with a high accuracy.
And even that is not all. Putting on board this glider a set of appropriate instruments, it can be easily turned into an effective stationary wind-power plant and the radar stations it will carry will make it possible to set up along this country's borders an antiaircraft and antimissile protective zone with an effective range of up to 250 km.
We have been examining the potentialities of the system with the AIST being "moored" and hovering at an altitude of 10 km over the ground in the tropospheric wind. But there are also other versions of its utilization. If the glider is fitted with a pilot's cabin, which is really no problem at all, it can fly roped up to a tug on land or on water and, changing its altitude and, partially, its course, carry passengers or cargoes of up to 1,000 kg over considerable distances.
And, as proved by further studies, this does not exhaust all the likely functions of the system. For example, in one of its versions AIST can be used in sport and advertising - for the promotion of parachute and glider sports, for creating high- altitude optical effects, for constant illumination of various objects, etc. And all of these things can be done either in an automatic or piloted modes.
But we won't even try to list all of the broad and unique potentialities of AIST simply because we do not know they all so far. But we can say with confidence that our system has a good chance of being entered into the Guinness Book of Records as "the slowest flying machine heavier than air". And our "products" have already been awarded two patents of the Russian Federation.
Recorded by Arkady MALTSEV
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