Sea monsters. WEEK Review
The wounded "Spitfire" was heavily pulled over the English Channel to the West, and it seemed that the damaged car and its pilot had no chance to reach the shores of Britain. When he completely lost altitude and was already flying, almost clinging to the plane of the wings for the crests of the waves, the pilot suddenly felt that the flight had stabilized. As if a soft invisible hand lifted the plane ...
This is exactly how fiction encounters of people with a screen effect are described in fiction. That is, with an increase in the lifting force of the wing and a change in the aerodynamic characteristics of the aircraft when flying near the shielding surface (water, earth, etc.), the incoming air flow forms an “air cushion”, which creates lifting force not only due to a decrease in pressure above the upper plane of the wing (as in ordinary aircraft), but due to the increased pressure under the lower plane, which can be created only at extremely low altitudes (less than the wing aerodynamic chord). The pressure surge must reach the surface, be reflected and have time to reach the wing. Hence an important conclusion: the larger the plane of the wing, the lower the flight speed and the lower the altitude, the stronger the screen effect. Now briefly leave the aerodynamics and turn to stories.
By the 60 years of the twentieth century, military technology reached such a level that two developed countries could destroy each other in a matter of hours. In such conditions, not so much the technical characteristics of “faster, higher, stronger”, but the cost weapons. In the development of marine systems, the Soviet Union, as usual, went its own way, and as a result there appeared a whole separate type of technology called "EKV", and here the USSR achieved, frankly, impressive successes.
The most lifting and cheapest form of transport is water (sea, river). Aviation transport is not comparable with water transport for energy costs. According to these criteria, the best transport aircraft looks like a flying embarrassment against the background of an old wooden longboat. At the longboat, the weight of the transported cargo can be 5 times its weight, and a very good aircraft (with fuel) weighs two to three times more than the transported cargo. Worse than air transport is only space rocket, where a payload weight of 1% of the starting weight can be considered an excellent result.
And so, the WIG, as it seemed then, harmoniously combined in itself the carrying capacity, the economy of sea-going ships and the enormous speeds of aircraft. I do not like to work with hypothetical things, just as I do not like the attraction of facts "by the ears." Therefore, let us turn to the actually existing structures and try to find out the strengths and weaknesses of WIG.
"Caspian Monster"
The giant ekranoplan KM-1, the brainchild of the Rostislav Alekseev design bureau. Empty mass - 240 tons., Maximum take-off weight - 544 tons (!). The only aircraft that broke this record is the An-225 Dream. Cruising speed - up to 500 km / h. Awesome!
But is it all so simple? Due to what were these magnificent characteristics achieved? Let's look at the photo: the first thing that catches your eye is 10 (ten!) VD-7 jet engines, each with 130 kN. Is it a lot or a little?
Here, for example, the same age as the Caspian Monster, the passenger Tu-154B. The Tupolev is equipped with three NK-8 turbofan engines with 100 kN thrust in takeoff mode. The maximum take-off weight of the Tu-154B is 100 tons. As a result, a simple proportion:
KM - maximum take-off weight 544 tons, total thrust 10 engines - 1300 kN.
Tu-154B - maximum take-off weight 100 tons, total thrust 3-x engines - 300 kN.
And where is the economy, like a sea vessel, about which we talked so much today? And she is not! And the answer is very simple: she has nowhere to take. Tu-154 flies at a height in the rarefied layers of the atmosphere, and the CM is forced to break through the dense air near the water itself. Tupolev has clean lines, a sleek and streamlined fuselage, narrow swept wings - compare this with the monstrous appearance of the CM, which only 8 engines mounted on the wings are worth! Monstrous air resistance eliminates all the advantages of the screen effect.
Another imperceptible reason for which the effectiveness of WIG is suffering is low speed. As we have already found out, WIG and aircraft engines consume approximately the same amount of fuel per unit of time in cruising mode. But the plane, due to greater speed, passes a much greater distance during this time!
Yes, 10 KM engines are supposedly needed only in take-off mode; when entering cruise mode, some of the engines are turned off. But then the question is: how long does this “takeoff mode” last? The answer will be the events of 1980 of the year - an attempt to reduce the cravings resulting in a catastrophe and the death of the "Caspian monster".
"Lun"
Ekranoplan-rocket carrier "Lun", the pride of the Soviet military-industrial complex, the talk of the town. The mass of empty - 243 tons. Maximum take-off - 388 tons. Speed - 500 km / h. Impressive.
"Lun" was built in duplicate and there is much more information on it than on its predecessor. So let's dwell on it in more detail.
Again, look at the beautiful photos. At this time, the ground effect vehicle is equipped with 8 jet engines NK-87 with 130 kN. Maybe these are some special efficient engines with minimal fuel consumption?
Not. NK-87 - modification of the turbojet NK-86 turbojet engine for the wide-body IL-86 airliner. The specific fuel consumption for the NK-86 is 0,74 kg / kgf / h in takeoff mode. A similar indicator for NK-87 is 0,53 kg / kgf • hour.
Here it is, saving, you will say happily. Unfortunately no. IL-86 uses the 4 engine, while Lun uses the 8. Moreover, the maximum take-off weight of the IL-86 is 215 tons, which is only one and a half times less than that of the WIG.
IL - a passenger plane on the 350 seats, and the "Lun" or "Caspian monster" - still cargo vehicles. Well, let's compare the “Lun” with the famous transport plane, I’m not afraid to say, the best aircraft in the world of its class is the An-124 “Ruslan”. With a maximum take-off mass of 400 tons to 150 tons, it may be attributable to USEFUL LOAD. An ekranoplan, alas, cannot boast with such an indicator - the Lunya payload is no more than 100 tons.
The flight range of the "Ruslan" with a load of 150 t - 3000 km, and with 40 tons of An-124 will fly to 11 000 km! What does the Lun offer us? 2 000 km, and the load is not specified in any source. Possibly empty.
And now let's list the obvious shortcomings of WIG:
First, the speed. The cruise speed of WIG - 400 ... 500 km / h, which is more than two times less than that of conventional jets.
On the other hand, 500 km / h - this is significantly higher than that of sea vessels. But, again, this is not all simple. A regular cargo ship or tanker makes 20 nodes with a load on average. Every hour, day and night, in a storm and fog, without refills and breaks. Profitability is not even worth comparing - ship diesel is much more economical than a jet engine for specific fuel consumption, and taking into account the difference in the cost of diesel and high-quality aviation kerosene ...
And again about the cost-effectiveness - the design of an airplane is twice as heavy as an airplane of the same size. Yes, when built instead of aviation technology, shipborne technologies are sometimes used, but this difference from the hardy covers the cost of 8 power plants and the enormous dimensions of the ship-aircraft. I'm not talking about the cost of maintenance: 8 engines - this is not a joke.
Secondly, a very important quality versatility. As we remember, the ground-effect vehicle is able to fly only over an almost perfectly smooth surface. Yes, it can with an effort fly over a low barrier (not higher than a couple of hundred meters) ... but, anyway, the areas of its use are limited to sea areas, large lakes and, possibly, tundra and desert. The very first forest line or power line will be the last for an ekranoplan. Unlike ekranoplans, for planes, the relief under the wing does not matter: where it is necessary, we will fly there.
Moreover, ekranoplans have very poor maneuverability. Experimental ekranoplan of Beriev Design Bureau - 14М1П (max. Take-off weight of 50 tons) every time you change course you had to stop, turn off engines and turn the tug in the right direction. Although according to calculations, he had to do it himself.
Thirdly, for the WIG is really no use. If urgent delivery of people and goods is required, it is more profitable to use an airplane. If you need to deliver a large shipment of cargo across the ocean - any customer will choose a ship, because better to wait a couple of weeks, but save millions.
Actually, “Lun” existed in 2 –x variants: the missile carrier with the 6 PKR “Mosquito” and “Rescuer”. I will not even speak about the missile carrier - it represented a danger only for its own crew (the height of a flight of a few meters does not give pilots the right to make a mistake). Moreover, the Tu-22M was much more powerful carrier "Mosquitoes" ...
"Rescuer" - sounds great. Night, shipwreck - and suddenly an ekranoplan jumps out of the darkness, picks up the victims, an EMERCOM mobile hospital is deployed on board ... and that's all saved! However, this has nothing to do with reality: in an hour, the place of the shipwreck will consist of people in inflatable vests scattered within a radius of several kilometers. As planned to carry out their search with a ground-effect vehicle, flying at a speed of 500 km / h a few meters from the water, remains a mystery. In any case, a small range of flight allowed the "Rescuer" to work only in coastal areas. And, tell me please, what is the difference between an ekranoplan and a conventional seaplane, the same amphibious Be-200? Seaworthy? But it is a myth, the storm is equally detrimental to the use of both means.
To use an ekranoplan for landing? Only Mistral is suitable for landing on overseas territories - there is a completely inadequate range and payload for EKP. To land with an ekranoplan landing in Georgia? But it is a very long way, much closer by airplanes through Madagascar.
Given all the above, it becomes clear the rapid extinction of the interest of the Soviet leadership to the topic of ekranoplanes, for 30 for years the entire 3 of such "monster" was released. Steep hybrid of the ship and the aircraft actually turned out to be a bad airplane and a bad ship.
Dear readers, you can draw your own conclusions from these facts and interpret my article in your own way. One thing is certain - buyers have already voted with a wallet - no army in the world is interested in monster-winged ekranoplanes, however, like commercial structures. All ekranoplan use is now limited to light flying rides for the amusement of the public.
Information