The wrecked Spitfire was dragging heavily over the English Channel to the West, and it seemed that the damaged vehicle and its pilot had no chance of reaching the coast of Britain. When he completely lost altitude and was already flying, almost clinging to the crests of the waves by the wing planes, the pilot suddenly felt that the flight had stabilized. As if a soft invisible hand lifted the plane …
This is how random encounters of people with a screen effect are described in fiction. That is, with an increase in the wing lift and a change in the aerodynamic characteristics of the aircraft when flying near the shielding surface (water, land, etc.), the incoming air flow forms an "air cushion", which creates a lift not only due to a decrease in pressure above the upper plane of the wing (as in conventional aircraft), but due to the increased pressure under the lower plane, which can only be created at extremely low altitudes (less than the aerodynamic chord of the wing). The pressure jump should reach the surface, reflect and have time to reach the wing. Hence an important conclusion: the larger the wing plane, the lower the flight speed and the lower the altitude, the stronger the ground effect. Now let's leave aerodynamics for a while and turn to history.
By the 60s of the twentieth century, military equipment had 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 "faster, higher, stronger" began to come to the fore, as the cost of the weapon. In the development of marine systems, the Soviet Union, as usual, went its own way, and as a result, a whole separate type of technology called "ekranoplanes" appeared, and here the USSR achieved, frankly, impressive successes.
The most lifting and cheapest type of transport is water (sea, river). Air transport cannot be compared with water transport in terms of energy consumption. According to these criteria, the best transport plane looks like a flying embarrassment against the background of an old wooden launch. On a launch, the weight of the transported cargo can be 5 times its weight, and a very good plane (including fuel) weighs two to three times more than the cargo being transported. Only rocket and space transport is worse than air transport, where a payload weight of 1% of the launch weight can be considered an excellent result.
So, the ekranoplan, as it seemed then, harmoniously combined the carrying capacity, the economy of sea vessels and the huge speeds of aircraft. I don’t like working with hypothetical things, just as I don’t like drawing facts by the ears. Therefore, let's turn to real-life designs and try to find out the strengths and weaknesses of ekranoplanes.
Caspian Monster
The giant ekranoplan KM-1, the brainchild of Rostislav Alekseev's design bureau. Empty weight - 240 tons, maximum take-off weight - 544 tons (!). The only aircraft to break this record is the An-225 Dream. Cruising speed - up to 500 km / h. Awesome!
But is it that simple? How were these excellent characteristics achieved? Let's look at the photo: the first thing that catches your eye is 10 (ten!) VD-7 jet engines, 130 kN thrust each. Is it a lot or a little?
For example, the same age as the "Caspian Monster" passenger Tu-154B. Tupolev is equipped with three NK-8 turbofan engines with a thrust of 100 kN in take-off mode. The maximum take-off weight of the Tu-154B is 100 tons. As a result, a simple proportion:
KM - maximum takeoff weight 544 tons, total thrust of 10 engines - 1300 kN.
Tu-154B - maximum takeoff weight 100 tons, total thrust of 3 engines - 300 kN.
And where is the efficiency, like that of a sea vessel, about which we talked so much today? But she is not! And the answer is very simple: she has nowhere to come from. The Tu-154 flies at an altitude in the rarefied layers of the atmosphere, and the CM is forced to break through the dense air near the water. The Tupolev has clean lines, a sleek and streamlined fuselage, narrow swept wings - compare this with the monstrous appearance of the KM, which only cost 8 engines installed on the wings! The monstrous air resistance negates all the advantages of the screen effect.
Another invisible reason due to which the efficiency of ekranoplanes suffers is low speed. As we have already found out, the engines of the ekranoplan and the aircraft consume approximately the same amount of fuel per unit of time in cruise mode. But the plane, due to its higher speed, covers a much greater distance during this time!
Yes, 10 KM engines are supposedly needed only in takeoff mode; when entering cruise mode, some of the engines are turned off. But then the question is: how long does this "takeoff regime" last? The response will be the events of 1980 - an attempt to reduce the thrust resulted in the disaster and death of the "Caspian Monster".
Lun
The missile-carrying ekranoplan "Lun", the pride of the Soviet military-industrial complex, a byword. Empty weight - 243 tons. Maximum takeoff - 388 tons. Speed - 500 km / h. Impressive.
"Lun" was built in duplicate and there is much more information on it than on its predecessor. Therefore, let's dwell on it in more detail.
We look at beautiful photographs again. This time the ekranoplan is equipped with 8 NK-87 jet engines with 130 kN thrust. Maybe these are some special efficient engines with minimal fuel consumption?
No. NK-87 is a modification of the NK-86 bypass turbojet engine for the IL-86 wide-body airliner. Specific fuel consumption for NK-86 is 0.74 kg / kgf • hour in takeoff mode. A similar indicator for NK-87 is 0.53 kg / kgf • hour.
Here it is, savings, you will be delighted to say. Unfortunately no. The Il-86 uses 4 engines, while the Lun has 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 ekranoplan.
Il is a passenger plane with 350 seats, and "Lun" or "Caspian Monster" are still cargo vehicles. Well, let's compare the "Lun" with the famous transport aircraft, I'm not afraid to say, the best aircraft of its class in the world - the An-124 "Ruslan". With a maximum take-off weight of 400 tons, up to 150 tons can be a PAYLOAD. The ekranoplan, alas, cannot boast of such an indicator - the "Lunya" payload is no more than 100 tons.
The Ruslan's flight range with a load of 150 tons is 3000 km, and with 40 tons the An-124 will fly 11000 km! What does "Lun" offer us? 2,000 km, and the load is not indicated in any source. It is possible that it is also empty.
Now let's list the obvious shortcomings of ekranoplanes:
At first, speed … The cruising speed of ekranoplanes is 400 … 500 km / h, which is more than two times less than that of conventional jet aircraft.
On the other hand, 500 km / h is significantly higher than that of sea vessels. But, again, not everything is simple here. An ordinary dry cargo ship or tanker makes an average of 20 knots with cargo. Every hour, day and night, in storm and fog, without refueling and breaks. Efficiency is not even worth comparing - a ship diesel is an order of magnitude more economical than a jet engine in terms of specific fuel consumption, and taking into account the difference in the cost of diesel fuel and high-quality aviation kerosene …
And again about efficiency - the ekranoplan design is twice as heavy as an aircraft of the same size. Yes, when they are built, instead of aviation technologies, shipboard technologies are sometimes used, but this difference is dashingly covered by the cost of 8 power plants and the grandiose size of the ship-aircraft. I'm not talking about the cost of maintenance: 8 engines are not a joke.
Secondly, a very important quality, versatility … As we remember, the ekranoplan is able to fly only over an almost perfectly smooth surface. Yes, it can with effort fly over a low obstacle (no higher than a couple of hundred meters) … but whatever one may say, the areas of its application are limited to sea areas, large lakes and, possibly, tundra and desert. The first forest belt or power line will be the last for the ekranoplan. Unlike ekranoplanes, the relief under the wing does not matter for airplanes: where we need to - we fly there.
Moreover, ekranoplanes have very poor maneuverability. Experimental ekranoplan KB Beriev - 14M1P (max. Takeoff weight 50 tons), every time you change course, you had to stop, turn off the engines and turn the tug in the right direction. Although, according to calculations, he had to do it himself.
Thirdly, for an ekranoplan really no application … If an urgent delivery of people and cargo is required, it is more profitable to use an airplane. If it is necessary to deliver a large consignment of cargo across the ocean, any customer will choose a ship, because it's better to wait a couple of weeks, but save millions.
Actually, "Lun" existed in 2 versions: a missile carrier with 6 anti-ship missiles "Moskit" and "Rescuer". I won't even talk about the missile carrier - it posed a danger only for its own crew (a flight height of several meters does not give pilots the right to make a mistake). Moreover, the Tu-22M was a much more powerful carrier of Mosquitoes …
Lifeguard sounds great. Night, shipwreck - and suddenly an ekranoplan jumps out of the darkness, picks up the victims, a mobile hospital of the Ministry of Emergency Situations is deployed on board … and now everyone is saved! However, this has nothing to do with reality: in an hour, the place of the shipwreck will be people in inflatable vests scattered over a radius of several kilometers. How it was planned to search for them from an ekranoplan flying at a speed of 500 km / h a few meters from the water remained a mystery. In any case, the short flight range allowed the Rescuer to work only in coastal areas. And, please tell me, how is the ekranoplane then different from an ordinary seaplane, the same Be-200 amphibian? Seaworthiness? But this is a myth, the storm is equally detrimental to the use of both funds.
To use an ekranoplan for a landing? Only the Mistral is suitable for landing on overseas territories - ekranoplanes have a completely insufficient range and carrying capacity. To land a landing party from an ekranoplane in Georgia? But it is a very long journey, much closer by plane through Madagascar.
Considering all of the above, it becomes clear that the interest of the Soviet leadership in the subject of ekranoplanes is rapidly fading away, in 30 years only 3 such "monsters" have been released. A cool hybrid of a ship and an airplane turned out to be a bad airplane and a bad ship.
Dear readers, you can draw your own conclusions from the above facts and interpret my article in your own way. One thing remains unquestionable - buyers have already voted with their wallet - not a single army in the world is interested in monster ekranoplanes, however, as well as commercial structures. All the use of ekranoplanes is now limited to light flying attractions for the entertainment of the public.
