Currently, intensive work is underway to create flying platforms (LP) designed for civil and military use in the city. The proposed projects can be conditionally divided into two schemes - screw with a rotor or rotor with high torque, located in a protective ring, and platforms made according to a nozzle scheme with a vertically positioned gas turbine engine and an ejector traction amplifier. Each of them has its own advantages and disadvantages. The circuit with a screw in a protective ring is most prevalent. It allows for existing engines to obtain an acceptable combination of fuel weight and flight duration.
Rice 1. The scheme of the flying platform: X-Hawk Military (Israel)
A typical representative of such a scheme is an X-Hawk Military armored personnel carrier designed to carry 10 people http://www.urbanaero.com/category/x-hawk#. Special advantages arise when using it in urban environments. Unlike land transport, it is not exposed to mine weapons and can deliver soldiers to a building at any level through a window, avoiding potentially dangerous staircases. A rescue unmanned version with a manipulator was created on the same base, which allows evacuating the wounded directly from the battlefield without the risk of additional loss of the platform’s crew. However, due to the large bearing area of the screws and the insufficient degree of armor booking, such a design is a convenient target for any weapon with a caliber larger than 7,62 mm. The location of the screws inside the platform case limits the usable volume of the LP.
Fig.2 The project of the British UAV "Hoher" carrying capacity up to 1 tf
A similar deficiency is devoid of the vertical take-off and landing UAV of the company Eysir (project 2009), whose screws are located above the LP case. Lifting propulsion engines create vertical thrust using the Coanda effect. Weight 1,5 tf, flight time 8 hours, speeds are not specified. Obviously, for such a scheme, there are significant losses to blow the case.
A variant of a flying platform with a loaded rotor occupying a small projection area and body volume is an American Dynamics Battle Hog 100x UAV drone, which is a UAV with fixed bearing surfaces capable of operating both in vertical take-off and landing mode and in normal airplane take-off mode and landing Fig.3. This makes it possible to use it both on land and at sea. Class I and II booking. According to the company, such a construction is a revolutionary development that can significantly affect the nature of hostilities in modern urban and counter-guerrilla warfare.
The device is designed to perform a wide range of tasks - conducting reconnaissance, monitoring the terrain, target designation and attack ground targets. The on-board equipment provides fully automatic control of both the device itself and the standard armament and payload of the modular architecture. The design is based on the patented American Dynamics high-torque rotor lift system (High Torque Aerial Lift, HTAL). Its use, firstly, made it possible to drastically reduce the size of the rotors, “hiding” them inside the fuselage, which simultaneously reduced their vulnerability to enemy fire. Secondly, the HTAL system allowed Battle Hog 100x to provide not only high payload, but also flexibility in choosing the application modes of the device, the possibility of vertical take-off and landing, freezing and flight at extremely low speeds, and also, according to the developers, the unique maneuverability of the device without using aerodynamic control surfaces (which also reduces vulnerability) or complex thrust vector control systems used in modern vertical take-off and landing aircraft.
Fig.3 The body and thrusters of the Battle Hog 100x armored drone: 1- horizontal thrust nozzle; 2-fan vertical thrust.
Considering the basic principles laid down in this and similar constructions, it should be noted straightforwardness and insufficient sharpness of thought manifested in the solution of this problem. What are the cost of wing fuel tanks? In fact, Battle Hog 100x is a repetition of the concept laid out in 1939 in the Il-2 attack aircraft, with the connection of modern microelectronics and is intended mainly for military operations in countries with minimal air defense systems that do not have the means to detect and influence channels and control centers like drone.
Providing a vertical lift in the nozzle scheme (Fig.4) with moderate fuel consumption, it was possible only recently. This scheme provides the most compact, high level of use of volume and, in the military version, a significant increase in the level of body armor. Experimental work in this area was carried out in the USSR and France. In accordance with them, the flying platform was a rectangular case in the corners of which four lifting TRDs RВ-162 were installed with ring ejector traction amplifiers (EUT) of 15,6 kN each. The insufficient fuel and economic efficiency of such vehicles was shown and they did not receive further development.
The low fuel efficiency of the LP made according to the nozzle scheme is due to the vertical position of the gas turbine engine, which leads to the limitation of the number of compressor and turbine stages, respectively, to an insufficient degree of air compression. Another significant drawback is the ingress of erosion products and exhaust gases into the engine air intake, which leads to a sharp drop in thrust during takeoff. The scheme assumes a much smaller footprint than the screw one, which requires an even more powerful engine.
Fig. 4 Flying platform made according to a nozzle pattern (USA)
However, according to the author, the nozzle scheme is more promising, since its drawbacks are not organic and, even now, can be overcome by creating a lifting powerplant (SU) of small size in height, which is fairly light, high power and economy. It is also possible to significantly reduce the speed of exhaust gases due to more efficient ejection of atmospheric air and a corresponding increase in thrust.
Usually, for small speeds typical of flying platforms (LP), (100-150 km / h), the thrust is increased by connecting an ejector traction amplifier (EUT). Ring single-stage EUT requires a certain ratio of diameter to height ~ 1 / 7, which significantly increases the envelope in height and frontal resistance. Slotted EUT has a smaller overall height and greater traction gain, but it is leveled by losses when distributing active gas.
The inability to fully realize the advantages of a slotted EIU, which has a Ku-2 coefficient of reinforcement, is due to the design of a standard gas turbine engine, whose exhaust geometry is determined by an axial compressor and an annular combustion chamber. In order to realize the advantages of a gap EUT, it should be integrated with a gas turbine engine creating a flat jet at the exhaust. The scheme of such a linear gas turbine engine is presented and its principle of operation is given in (One of the possible directions for the use of a pulsating detonation engine [Electronic resource] / Yu.S. Podzirey // Engine. - 2010. - No. 3 (69). - Access mode: http : //engine.aviaport.ru/issues/69/page22.html.) Exhaust jet stretched across the flow and directed into the slotted ECU will allow to distribute the thrust evenly along the side of the platform. In this case, it becomes possible to reduce soil erosion and, accordingly, increase the allowable location of the platform. The efficiency problem is solved by connecting another amplifier to the linear gas turbine engine — a pulsating detonation engine (PUD), which, unlike the well-known Schmidt pipe, has a resonant valve-free inlet, compression ratio of the fuel mixture 100-150 units, fuel preprocessing and pulsation frequency 3 - 10 kHz. Its efficiency ~ 0 ,, 7 www.findpatent.ru/patent/243/2433293.html.
The design of the CCD itself is more technological and it is more reliable than the CCD with an axial, centrifugal or diagonal compressor. In connection with the turn of the air flow after each step, there are no brake-straightening vanes in it
Analysis of typical failures of gas turbine engines during operation shows that the majority of damage to the blades is fatigue due to their cantilever attachment. In the proposed GTE blades are attached at both ends. Strengthening their carrying capacity with a long engine length, possibly due to rings, periodically located in the plane orthogonal to the longitudinal axis of the impeller.
To ensure the forward movement of the LP it is proposed to use the main engine whose circuit is given in the work. Podzirey Yu.S. Mobile technological complex for remote processing of radioactive waste. / / Aerospace equipment and technology. No.4 2011. In contrast to the lifting engine, it provides exhaust from the nozzle, orthogonal to the flow of atmospheric air entering through the air intake. archive.nbuv.gov.ua/portal/natural/AKTT/2011_4/Podzirey.pdf (Podzirey Yu.S. Mobile mobile complex for remote processing of radioactive waste. / / Aerospace Engineering and Technology. No. XXUMX 4). Especially lifting Part of the SU is a powerful supersonic exhaust PUDD having a high temperature (up to 2011 C) and subsequent sharp cooling. A preliminary estimate shows that with a total length of 3000 x 4 m and a maximum fuel cycle temperature in the turbine part of the SU no more than 8 C, the take-off weight of the platform can be of the order of 15000 tf. The main constant part of the vertical thrust ~ 100% is created by pulsating amplifiers of thrust, the indicator efficiency of which is of the order of 80, which ensures special economics of the SU. The rest of the thrust is created by a less economical (efficiency ~ 0,7) turbine part, the task of which is to provide boost to the airfoil and to create some adjustable excess thrust required to control the platform in height, roll and pitch.
In fig. 5 presents the integration of control systems with a rectangular PL case, which can be implemented, depending on the degree of protection and equipment placed inside the building as fire prevention, armored personnel carrier with anti-rifle protection, a flying tank, a salvo fire system carrier or an air defense system, a command headquarters, ambulance transport, fuel tanker, etc. The arrangement of the nozzles of the gas-dynamic control 10 in the horizontal plane at the corners of the platform allows for large control moments. Compressed air for them can be selected after the second stage of the compressor of the lateral lifting gas turbine engine. In the same place, compressed air is taken for the reverse nozzles (not shown in figure 5). The resulting loss of thrust (~ 10%) for two of the four lifting engines is an inevitable price to pay for the high maneuverability of the platform.
Fig.5 Armored vehicle in the version of the BMP-T: 1 - lifting engine; 2 is a confuser of a slit ejector thrust amplifier (EUT); 3 - payload compartment; 4 - armor tower of circular rotation; 5 - body; 6 - chassis; 7 - EUT mixing chamber; 8 - dynamic protection compartment; 9 - positioning system sensor; 10 - course control nozzles; 11 - height control flaps; 12 - lifting engine air intake; 13 - main engine air intake: 14 - main engine nozzle; 15 - marching engine; 16 - landing hatch; 17 - fuel tanks; 18- ammunition
The design of the LP has two modes of movement - free flight mode, when the thrust of the engines exceeds the weight, and the economical mode of screen flight, when an overpressure is created under the vehicle's bottom due to reflection of exhaust from the screen. In fig. 6 a shows the distribution of gas jets in this mode. It should be emphasized that this mode is the mode of the fountain effect, which was first discovered for vertical take-off and landing aircraft. The free flight mode (fig. 6 b) is necessary to overcome various obstacles and movement on highly rugged terrain. It is especially effective in the conditions of urban development, when the concept of “street” disappears, and in the conditions of a desert area, when the platform occupies a high-altitude echelon precluding the formation of a unmasking dust cloud.
The dimensions of the platform must allow its transportation by rail. It can be delivered to remote theaters of war by transport aircraft and parachute without parachute systems due to braking in vertical and horizontal planes with its own engines, starting at a height of ~ 500m and at a considerable distance from the intended target. This significantly reduces the effectiveness of the possible impact of air defense weapons.
Figure 6 Flying armored personnel carrier (cross section) in screen mode a) and free flight b). 1 - body; 2 - distribution of power plant exhaust; 3 - screen surface.
A preliminary rough estimate of SUs for the area of air intakes shows that with a total length of 4 x 8 m engines and a maximum fuel cycle temperature in the turbine part no more than 15000 C, the platform take-off weight may be of the order of 100 tf. The main constant part of the vertical thrust ~ 80% is created by pulsating amplifiers of thrust, the indicator efficiency of which is of the order of 0,7, which ensures special economics of the SU. The rest of the thrust is created by a less economical (efficiency ~ 0,3) turbine part, the task of which is to provide boost to the airfoil and to create some adjustable excess thrust required to control the platform in height, roll and pitch.
Armament, security and features of the use of the platform.
In the context of the dynamic improvement of anti-tank weapons of foreign countries, there has been a significant vulnerability of various modifications of the T-72B, T-80U, T-90 and BMP that are in service. The Ossetian-Georgian conflict that has taken place has shown that the troops have practically no highly protected means of transporting infantry on the march and on the battlefield. The redeployment of troops is the part of the fighting in which they are most vulnerable to the impact of sabotage groups, as well as nuclear weapons or weapons of large volume. The unsuccessful experience of using armored personnel carriers in local conflicts is due to several factors. The most important - they were designed to protect against attacks from the front hemisphere and, taking into account such tasks, their booking was built. Shelling from an ambush or laying mines in this case allows the enemy to strike at the least protected parts of the armored vehicle.
Over the past years, numerous attempts have been made to get rid of these problems and provide all-round protection for infantry fighting vehicles against various weapons, including anti-tank ones. As a result, a new armored vehicle concept was formed under the name MRAP (Mine Resistant Ambush Protected - “Protected against mines and ambush attacks”), which implies the use of relatively powerful protection of the sides and a number of measures to prevent the serious consequences of a mine explosion. The concept of a heavy and well-protected armored personnel carrier was embodied in metal and tested in practice several decades ago. The resulting machine with a combat weight of 52 tons retained the basic level of protection tankbut could carry up to ten soldiers with weapons. The experience of combat use confirmed the correctness of the chosen path. However, the dependence of such an armored personnel carrier on mine weapons and the condition of the supporting surface is obvious.
Fig. 7 Multiaxial car chassis for transporting and launching tactical Iskander-M missiles.
Figure 8 Unified off-road vehicle based on a flying platform.
1- case casement, 2- confuser of an ejector amplifier of thrust, 5- lifting device, 6 –– platform control panel, 7 –– missile control panel, 8 –– missile attachment points ,. 9 - rocket container, 10 - propulsion engine, 11-chassis in the released state, 12- chassis in flight mode, 13 - lifting engine, 14 ejection thrust mixing chamber, 15- fuel tank.
In addition to the version of an armored personnel carrier with counter-round all-round reservation, the platform can be made in a lightweight version for the transport of modules - the 4 position pic. 8. The module can be designed as a removable container for various goods or a passenger for transporting the wounded with equipment to provide primary emergency assistance. The above design LP is not tied to the road network and terrain. Using the platform as part of the missile complex fig. 8б, allows you to select the starting position regardless of the road network and terrain, which greatly expands its capabilities compared to the complex on the car chassis Fig.7. The LP form provides the minimum amount of the reflected radio frequency signal of ground-based XR stations, and the allowable thickness of the sheets of the LP case allows the all-view protection of the missile from special sniper rifle weapons that can be used by sabotage groups at a distance of up to 2,5km. LP can take the starting position individually, without engaging the engineering troops. As a support-free vehicle, the platform is not subject to the action of a mine weapon, and a large take-off weight will allow it to provide dynamic and passive protection from any direction, including from the stern. Protection of the platform from above should be carried out exclusively by active means of threat suppression. No less important means of protection are high speed, maneuverability and unrestricted maneuverability and the possibility of reaching the target from an unexpected direction for the enemy.
High SU, due to a large area of air intakes, exhaust nozzles and, most importantly, a significant temperature of the SU fuel cycle (up to 30000 С). This, and the lack of undercarriage, allows you to fully equip the platform in the armored version of the vehicle with means of protection against modern tandem and kinetic anti-tank weapons. As a weapon, conventional artillery, small arms or rocket armament with sufficient ammunition can be used. To defeat closed and unobservable targets, it is possible to equip LPs with weapons systems capable of striking targets observed by troops who conduct active hostilities outside the machine.
Installation on the platform of ground-to-air missiles will allow it to be used as an effective means for hitting targets flying at low and extremely low altitudes.
A flying tank or an armored personnel carrier with anti-missile protection in the above-described form has a worse rate of climb, a smaller static ceiling and horizontal speed, compared to a fire support helicopter, but it is designed to work at extremely low altitudes in dense urban settings, mountain or marshland. Its use is also beneficial due to greater ease of operation, manufacturability of repair and low cost production of SU. The PL does not have vibrations typical for the helicopter, which creates favorable conditions for the operation of the equipment and crew.
In the above material, aimed at improving and eliminating the backlog of the national military armored vehicles, there is nothing fundamentally new from a scientific point of view. From a technical point of view, the necessary groundwork (both for the engine and for the hull) can be performed on existing equipment, which is reasonably well developed for the production of conventional armored vehicles and conventional gas turbine engines with axial compressors. The undoubted advantage of the proposed vehicle over the fire support helicopter is the absence of such complex and vulnerable parts as a rotor with a swashplate, a tail rotor, a massive gearbox, as well as providing greater capacity or armor, the ability to fly in a limited space at extremely low altitude and a safer takeoff and landing on the swinging deck when performing amphibious assault. The release of the platform in civilian fire-fighting variant will reduce the cost per square meter of housing and the cost of its maintenance, which can provide additional financial resources for the release of the platform in various ways, including a flying tank or an armored personnel carrier with anti-rifle protection capable of providing fire support to infantry.