The missile ship-ekranoplan Project 903 "Lun" (NATO codename: Utka) is a Soviet strike ekranoplan missile carrier of Project 903, developed at the Central Design Bureau for Hydrofoil Ships named after Rostislav Alexeyev under the leadership of the designer Kirillov.

The ekranoplan is intended to strike surface ships with a displacement of up to 20,000 tons, including those from naval strike groups, landing units, convoys, and single ships, both displacement-type and those on hydrofoils and air cushions, outside the enemy's aviation counteraction (including AWACS). Thanks to its relatively high speed (for surface and low-altitude carriers) and stealthiness to ship radars, the "Lun" ekranoplan can approach targets within missile launch range.

The flight principle of ekranoplans differs significantly from that of conventional airplanes or hovercraft. The ekranoplan is supported in the air also by an air cushion, but it is not generated by special engines; instead, it arises from the oncoming airflow.

A conventional airplane takes off and flies because the shape and profile of its wing create lower pressure above the wing surface than below it. For the ekranoplan, it is different. Due to air disturbances under its wing, a high-pressure area is created that reaches the surface and reflects back. This is called the ground effect. It can only be created at very low altitudes. It depends on the wing shape and aspect ratio, so the wings of an airplane and an ekranoplan differ greatly.

The first "Lun" was laid down in 1983 at the experimental plant "Volga," attached to the Central Design Bureau in the city of Gorky. On July 16, 1986, the ekranoplan was first launched into the water and subsequently transferred to the city of Kaspiysk for further testing and completion. In March 1987, design sea trials began, followed by factory trials in July 1989. State trials concluded on December 26, 1989. In 1990, the ekranoplan was handed over for experimental operation, which ended a year later in 1991.

The "Lun" ekranoplan was part of the 236th division of ekranoplan ships of the Caspian Flotilla. Initially, it was planned to build eight missile ekranoplans of the "Lun" type, but due to financial problems and military feasibility, these plans were not realized. Nevertheless, at the time work on Project 903 ekranoplans ceased, another "Lun" ship was under construction but was not completed.

As of December 2001, the "Lun" ekranoplan was not listed in the Russian Navy, meaning it was decommissioned. It was mothballed in a dry dock at the "Dagdiesel" plant in Kaspiysk. All classified electronics were stored in warehouses.

The ekranoplan is built on a monoplane aircraft scheme with a trapezoidal wing planform. Structurally, the ship includes a hull, a wing with endplates, and a T-shaped tail unit with control rudders. At the bow of the "Lun" is a horizontal pylon supporting eight main NK-87 engines housed in engine nacelles. Six containers for Moskit anti-ship missiles are mounted on top of the hull at an angle to the horizon.

The defensive artillery armament of Project 903 consisted of bow (located in the stand of the forward Moskit missile launchers) and stern artillery mounts with twin 23-mm 2-barrel GSh-23 aircraft cannons. These mounts were standardized and also installed on Il-76 and Tu-95MS aircraft.

The hull, with a height of 19 meters and length of 73 meters, is divided by bulkheads into ten watertight compartments. The center wing section is located amidships, and a hydro-ski device (used during landing) is located under the hull bottom. The hull has three decks used for housing service equipment and the missile complex crew. The hull is made of pressed panels, sheet, and profile materials from aluminum-magnesium alloy. The skin thickness ranges from 4 to 12 millimeters.

The wingspan is 44 meters, with an area of 550 square meters. It is made entirely of metal and has a multi-spar structure. The wing is watertight except for the tail section and flaps. Fuel is stored in four wing compartments. The endplates have a streamlined shape and are all-metal welded structures. The flaps are divided into twelve sections and have a riveted construction made of sheets and profiles.

The lower part of the hull is protected by paint coatings combined with corrosion protection.

It is not entirely correct to speak of the advantages or disadvantages of the "Lun" ekranoplan because it possesses all the characteristics typical of such vehicles. The military were always concerned about the low protection of ekranoplans, making them quite vulnerable to enemy fire. Its speed is comparable to that of a slow airplane, and the lack of anti-aircraft armament made ekranoplans easy prey for enemy aviation.

Undoubtedly, the advantages of ekranoplans include an excellent combination of speed and payload capacity. They can move at airplane speeds (up to 600 km/h), while their payload is comparable to that of a small ship.

Ekranoplans are very durable; in case of an accident, they can simply land on water even in relatively rough seas.

Such vehicles can fly not only over water surfaces but also over any flat terrain: desert, tundra, ice.

Ekranoplans are very economical: during flight in ground effect, they consume 30% less fuel than traditional airplanes.

These vehicles do not require an airfield, only a small water area or flat land is sufficient.

Another advantage of the ekranoplan is its low radar visibility due to flying at an altitude of just a few meters.

However, this type of aircraft has serious drawbacks that significantly complicate their operation.

The main one is that ekranoplans cannot fly over uneven surfaces, as the ground effect cannot be created in such conditions. However, this drawback does not apply to ekranolifts (such as the "Orlyonok"), which can fly like airplanes.

Ekranoplans have very low maneuverability and a large turning radius.

Despite being more economical than airplanes, an ekranoplan requires very high thrust-to-weight ratio for takeoff, necessitating the installation of takeoff engines that do not operate during flight.

Controlling an ekranoplan requires special skills and differs significantly from piloting an airplane.

Moreover, the "Lun" ekranoplan is a ship by definition and should primarily be compared with ships rather than airplanes. Compared to advanced combat ships produced worldwide, the "Lun" ekranoplan has a tenfold speed advantage.

On January 25, 2020, a decision was made to transport the ekranoplan to the "Patriot" park under construction in Derbent.

On July 30–31, 2020, the ekranoplan was towed by sea to the shore near Derbent, thus accomplishing a complex navigational and engineering task.

Subsequently, the ekranoplan was pulled ashore, and in 2021 the "Lun" is exhibited in the under-construction "Patriot" park, which is scheduled to open in 2023.

Sources:

https://ru.wikipedia.org/wiki/Lun_(ekranoplan)

https://army-today.ru/tehnika/ekranoplan-lun