Recovered another article published on the web ...
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Ground Effect Let's talk briefly of the vehicles that use ground effect to fly. But before that, we'll see a short introduction to find out what it is. A plane flies by wing shape, not at this point is nothing new for us. Has explicado in many ways, with the Venturi effect, with fluid flow (vortex lines, free vortices ...), and even saying that the air circulating through the top surface (upper profile) to arrive at the trailing edge while the flowing through the soffit (bottom). Some are more scientific basis than others, some are more correct than others, and we will not discuss them. All come to conclude the same, that is what interests us: the air circulating through the top surface makes it faster than it does for the soffit, this makes the Palamós n on top of the wing is lower than the pressure securcute n extradósy obtained on a force that makes the bird fly in question.
This force is decomposed conveniently as the sum of two components: one parallel to the flight speed (resistance) and one perpendicular (lift). The lift is what enables us to take off the feet of the ground, and the resistance that opposes our progress. If we have the weight of the push / pull avióny supplied by the jet engine, propeller ... We have the four forces of flight. The total lift of the plane is the sum of lift of the wing, tim &; Oacute n horizontal (remember that is a small wing) and the fuselage (depending on the fuselage, it will maso least important). We can break down resistance in the resistance that gives the airframe itself, fairings, wheels are retractable, antennas ... etc, and wing and rudders. In the wing, we see that part of the resistance is given by the simple act of generating lift, another part will be for the wing, and we have a better term, induced drag.
As the pressure in the bottom of the wing is lower than the top, this creates in the tips of the wings generate some eddies, orWe wingtip vortices. These eddies are the resulting aerodynamic lean further back, increasing the resistance. This increase was induced resistance. As shown in the picture above, the farther you are from the wing tip, the lower the effect of vortex on the wing. That is why if you have wings of high aspect ratio (aspect ratio gives us the measure of how long wing-span, compared to its width-string-), the effect of the turmoil will be charged in a area near the wing tip, but very small compared to the rest of the wing. That is why they invented the winglets, deposits inwingtip and other methods to reduce induced drag. Another way to reduce the effect of induced resistance is flying low, the appearance of ground effect, and this is the drawing on the Ekranoplanos to fly.
As seen above, if the scale on the string is large, the effect of the vortices is lower. Flying low, you get a similar effect, increasing the effective size, increasing same lift, and reducing induced drag: This is the ground effect.
Ekranoplano CH TMLXC
Since the beginning of the flight in heavier-than air, the pilot, near the ground at takeoff or landing when the plane is almost parallel to the ground and nearly é l, notice how the wings are pulled up more than usual, and the engine pulls forward more than normal. A call this the aeronautical ground effect: An increase in the lift force (the force that gives the wings and lifting the aircraft from the ground) and reduces the resistance (the force that pulls behind the aircraft, which has to overcome the engine). The resistance can be broken into two, due to air friction and thatappears that the wing asserted, induced resistance. It is the latter decreases.
The floor effect occurs when the flight altitude above the ground is the order of magnitude of the chord.
While initially this effect was unknown and even accidents caused scares, has been used by engineers and pilots. Thanks to this, the helicopters can carry the same weight by consuming less or equal weight to consumption, if kept relatively close to the ground instead of rising a lot (to a flight altitude of the order of magnitude dia ; meter rotor). I take advantage of thissmo Ekranoplano born effect.
In 1932 he developed the first device that takes advantage of this phenomenon (T. Kaario Finnish engineer): basically a device based on a flying wing "aircraft without rudder-designed the 20 which showed controllable near the ground, but ungovernable if was soaring. At the same time, N. Troong, a Swiss engineer, designed a 30-ton aircraft - too big for that time! - To fly very close to the ground, taking advantage of ground effect. Found that they needed much less power to keep the bird in flight if the manteníaa a height approximately equal to the wing chord (the line labeled as the chord line airfoil attached)
Although his studies were never concluded, searched for the following work.
During the 60 Rostislav Alexeyev Russian, and German Alexander Lippisch independently continued to develop vehicles that took advantage of ground effect. Russian engineer began developing their "ekranoplanos" which were heavily subsidized by the Soviet government once their military discovered the potential of the new vehicle. Alexeyev design & orcute, the 550 ton KM Caspian Sea Monster, the most ambitious ekranoplano (weighs more than 100 times larger ekranoplano built and flew a. .. 350mph!-560km / h ), and its development was halted only after the fall of the Soviet Union in 91. Not because it is an idea that has been forgotten, Boeing Phantom Works are currently working on similar devices, such as the Pelican
Caspian Monster
Pelikan
far as Americans are just that, only projects. The most spectacular devices are the Soviets stopped developing for lack of fundsafter the fall of the Soviet Union. There he developed as a transport aircraft, civil and military, and as attack aircraft, capable of carrying up to 6 cruise missiles, and aircraft to transport troops to assault the beach itself and support them with dog ; ones 76mm ...
The largest Ekranoplano: A-90 Orlyonok
ship was a Navy attack Soviet tanks capable of carrying up to the beach, because the nose is opened , as the current carriers. Could carry 6 cruise missiles SS-N-22 and a 76mm cannon. Iba powered by a turboprop engine and two large counter-rotating propellers. Subsequent developments led to Utka, the Mon ... but the crisis of a political system dragged down many aviation projects, including this one.
Mon firing a missile
were built four of these devices, one for testing. Sometimes we speak of a fifth, being but one of these, which crashed after it was rebuilt with new materials.
If you publish any more papers maso recerdo one, I'll leave here. Meanwhile, I leave a link to 
