Piaggio P119 engine

Piaggio P.119 Experimental Fighter

By William Pearce

Founded in 1884, Piaggio was an Italian industrial firm that began making aircraft under license in 1917. In 1923, Piaggio began building aircraft of its own design, led by Giovanni Pena. In the early 1930s, Piaggio began to manufacture aircraft engines under license. In 1936, Pena left the company and was replaced by Giovanni Casiraghi. Casiraghi had previously worked for the Waco Aircraft Company in the United States for several years.

Piaggio P119 mockup

Mockup of the Piaggio P.119 in the Finale Ligure plant. Note the guns in the wing. They appear to be 7.7 mm (.303-cal), but it is not clear. Only two machine guns are in the nose.

In 1938, Casiraghi began to design a new single-seat fighter of a rather unconventional configuration. He aspired to create a fast and maneuverable fighter that utilized as many Piaggio-sourced components as possible—the aircraft, engine, and propeller were all manufactured by Piaggio. Designated as the Piaggio P.119, the fighter design was submitted to the Regia Aeronautica (Italian Royal Air Force) on 18 March 1939. While the Regia Aeronautica was busy with other projects, Casiraghi continued to refine the fighter. The experimental P.119 was not ordered until 2 June 1941.

The P.119 had a conventional layout with the exception of the engine installation. The air-cooled, radial engine was located in the fuselage, behind the pilot. An extension shaft extended from the engine, under the cockpit, and to the propeller gear reduction at the front of the aircraft. This configuration provided good pilot visibility and enabled the armament to be centrally located in the aircraft’s nose and the engine to be located at the aircraft’s center of gravity, which enhanced maneuverability.

Piaggio P119 construction

The P.119 under construction at Finale Ligure. Note the tubular-steel center section of the engine mount and the frame of the aileron awaiting its fabric covering.

The P.119 had an all-metal airframe made up of three sections. The front and rear fuselage sections had an aluminum frame covered with aluminum panels, creating a monocoque structure. The center section, which supported the engine and wings, consisted of a tubular steel frame covered with aluminum panels. The entire fuselage possessed a circular cross section. Under the conventional tail was a non-retractable tailwheel. The all-metal wings had two spars and housed the fully retractable main wheels. Large ailerons occupied the outer half of the wings’ trailing edge, with split-flaps running along the remaining trailing edge of the wing. All control surfaces had an aluminum frame and were covered with fabric. Each wing contained an 87-gallon (330 L) fuel tank, and a 90-gallon (340 L) fuel tank was located in the fuselage behind the engine.

The cockpit was placed above the wings’ leading edge and covered with a canopy that hinged to the side (some sources state the canopy slid back). However, it does not appear that the hinged canopy covering was installed. Behind the cockpit was a tubular-steel frame that supported the air-cooled radial engine and connected the aircraft’s nose section, wings, and tail section. Originally, a 1,700 hp (1,268 kW) Piaggio P.XXII engine was to be used, but delays with that engine resulted in the substitution of a 1,500 hp (1,119 kW) Piaggio P.XV. Both engines had 18 cylinders and displaced 3,237 cu in (53.0 L). A scoop located under the aircraft’s nose brought in cooling air that was distributed annularly into the cooling fins of the engine’s cylinders with baffles helping to direct the airflow. The cooling-air exited via a semi-annular line of cowl flaps set atop the fuselage. Just behind the cockpit was the engine’s intake, and the exhaust was expelled from four stacks forward of the cowl flaps. The P.119’s variable-pitch, three-blade propeller was made by Piaggio and was 10 ft 10 in (3.3 m) in diameter.

Piaggio P119 engine

Nicolò Lana in the cockpit of the P.119 preparing for an engine run. The canopy has been removed, and only two machine guns are installed in the nose. The two left-side exhaust stack openings are visible in front of the open cowl flaps.

The aircraft’s armament consisted of four 12.7 mm (.50-cal) machine guns positioned in the nose above the propeller gear reduction and a 20 mm cannon that fired through the propeller hub. The machine guns had 500–550 rpg (the number varies by source), and the 20 mm cannon had 110 rounds. Some sources state that provisions existed to install two additional machine guns in each wing with 400 rpg. However, those sources disagree on whether the guns were 7.7 mm (.303-cal) or 12.7 mm (.50-cal). A mockup of the P.119 included the wing guns, which appear to be 7.7 mm (.303-cal), but the mockup also appears to have only two nose machine guns. Images of the P.119 prototype do not indicate any provisions for wing guns. Reportedly, the prototype did not have the cannon or two of the four nose machine guns installed. Consideration was given to a ground attack version with a 37 mm cannon firing through the propeller hub, and a bomb rack under each wing and under the aircraft’s centerline.

Piaggio P119 rear

Rear view of the P.119 illustrates the aircraft’s relatively clean exterior. The aircraft is at Villanova d’Albenga, presumably before its first flight.

The Piaggio P.119 had a wingspan of 42 ft 8 in (13.0 m), a length of 31 ft 10 in (9.7 m), and a height of 9 ft 10 in (3.0 m). The aircraft had a top speed of 398 mph (640 km/h) at 22,310 ft (6,800 m) and a stalling speed of 81 mph (130 km/h). The P.119 had an empty weight of 5,886 lb (2,670 kg) and a maximum weight of 9,039 lb (4,100 kg). The aircraft had an initial rate of climb of approximately 3,077 fpm (15.6 m/s), and a climb to 19,685 ft (6,000 m) took 7 minutes and 15 seconds. The P.119’s ceiling was 41,011 ft (12,500 m), and it had a maximum range of 932 miles (1,500 km).

Some sources indicate that two P.119 prototypes were ordered and given the Matricola Militare (military registration number) of MM 496 and MM 497, with MM 496 used on the mockup and MM 497 applied to the actual prototype. It is not clear why a mockup would need a serial number, and other sources contend that MM 496 was assigned to the prototype. However, MM 496 appears to have been assigned to the Piaggio P.108C prototype four-engine transport, and the majority of sources state that MM 497 was the P.119 prototype.

Piaggio P119 painted

The P.119 undergoing an engine run. Note the scoop that brought in cooling air for the engine. The aircraft had a fairly wide-track landing gear.

The P.119 was built at Piaggio’s Finale Ligure plant in western Italy. The aircraft was completed in late 1942 and underwent ground tests in mid-November. The P.119’s first flight occurred on 19 December 1942. The aircraft was flown at Villanova d’Albenga by Nicolò Lana. The initial flight testing revealed that the P.119 suffered from engine cooling issues, requiring the cowl flaps to stay open. The open flaps slowed the aircraft and caused its nose to pitch up. Other issues included vibrations from the engine and extension shaft installation and general instability of the P.119. These issues resulted in complete flight trails not being conducted, and aerobatic maneuvers were not attempted. On 2 August 1943, the P.119 was damaged when the brakes locked up on landing, causing the aircraft to nose over. The damage was minor and mostly limited to the propeller and a wing, but the aircraft was not repaired before the Italian surrender on 8 September 1943. Problematic and difficult to fly, the P.119 subsequently disappeared and was presumably scrapped.

Piaggio P119 noseover

The P.119 after it nosed over during landing on 2 August 1943. While the aircraft has been painted, it does not appear that the canopy cover has been installed. Note the deployed split flaps, and the intake scoop behind the cockpit.

Dimensione Cielo 3: Caccia Assalto by Emilio Brotzu, Michele Caso, Gherardo Cosolo (1972)
Volare Avanti: The History of Piaggio Aircraft by Paolo Gavazzi (2000)
War Planes of the Second World War: Fighters, Volume Two by William Green (1961)
Italian Civil and Military Aircraft 1930-1945 by Jonathan Thompson (1963)

Lorraine 12Fa

Lorraine-Dietrich ‘W’ Aircraft Engines

By William Pearce

In the early 1900s, Lorraine-Dietrich was a French manufacturer of wagons, rail equipment, and automobiles. During World War I, the company’s factory in Argenteuil, France started manufacturing aircraft engines under the name “Lorraine.” The Argenteuil factory was led by Marius Barbarou, the engineer that designed the aircraft engines.

Lorraine 12F

The Lorraine 12F of 1919 was the first of the company’s W-12 engines and followed the design outlined in the 1918 patent. Note the exposed pushrods and enclosed valves.

By 1918, Lorraine had developed aircraft engines in the form of an inline-six, a V-8, and a V-12. However, Barbarou began to experiment with engines of a W configuration. The W (or broad arrow) engine configuration had the benefit of being more rigid and slightly lighter than a comparable V-12, with the drawback of being slightly taller and wider. On 5 June 1918, Lorraine (under Barbarou) applied for a patent in which the benefits of a W engine with either four, six, or eight cylinders per bank was described. While the British Napier Lion W-12 was being developed at the same time, the patent illustrates that the Lorraine W engines were a parallel development and not a copy of the Lion. French patent 504,772 was awarded on 22 April 1920 for the W engine design.

The first generation of Lorraine’s W engines was designed around 1918 and known as the 12F (many sources do not give a designation for this engine, and “12F” was used again). The liquid-cooled, 12-cylinder engine consisted of a two-piece aluminum crankcase that was split horizontally along the crankshaft’s axis. Three banks of cylinders were mounted atop the crankcase, and the left and right banks were angled 60 degrees from the center, vertical bank. Each cylinder bank had two pairs of two cylinders. Each pair of steel cylinders was surrounded by a welded steel water jacket. Atop each cylinder was a single intake valve and a single exhaust valve. The enclosed valves were each actuated by a partially exposed rocker and a fully exposed pushrod. All of the pushrods were controlled by two camshafts—one positioned in each Vee between the cylinder banks. The push rods that controlled the exhaust valves for the left and right cylinder banks had a lower roller rocker that followed the camshaft.

A single-barrel updraft carburetor was positioned on the outer side of the right cylinder bank. An intake pipe led from the carburetor, passed between the two cylinder pairs of the right bank, and joined a manifold. The manifold split into four branches that fed each of the cylinders on the right bank. Employing a similar configuration, a two-barrel carburetor on the left side of the engine fed both the left and center cylinder banks. Each cylinder had two spark plugs that were fired by two magnetos located at the rear of the engine. The left magneto fired the spark plugs on the intake side of the cylinders, and the right magneto fired the exhaust-side spark plugs.

Lorraine 24G

With a new crankcase, crankshaft, and camshafts, the 24-cylinder 24G of 1919 was more than just two 12F engines coupled together. Note the ignition system driven from the propeller shaft.

The flat-plane crankshaft had four throws and was supported by three main bearings. A master connecting rod was attached to each crankpin. The master rods were connected to the aluminum pistons in the vertical cylinder bank. Articulated rods connected the pistons in the left and right cylinder banks to the master connecting rods. The engine had a compression ratio of 5.2 to 1. The propeller was attached directly to the crankshaft without any gear reduction. The Lorraine 12F had a 4.96 in (126 mm) bore and a 7.09 in (180 mm) stroke. The W-12 engine displaced 1,826 cu in (29.9 L) and produced 500 hp (372 kW) at 1,600 rpm. The 12F weighed 960 lb (435 kg).

While work on the 12F was underway, a 24-cylinder engine was designed that was basically two 12Fs. The W-24 engine was designated 24G (many sources do not give a designation for this engine, and a different G-series emerged later). Other than having twice the number of cylinders, the main change from the 12F was that the ignition system was driven at the front of the engine. The 12G’s eight throw crankshaft was supported by five main bearings. The W-24 engine displaced 3,652 (59.9 L) and produced 1,000 hp (746 kW) at 1,600 rpm. The direct drive engine weighed 1,874 lb (850 kg), and it was estimated that a 16 ft 5 in (5 m) propeller would be needed to harness its power.

The 12F and 24G engines were built during 1919 and displayed at the Salon de Paris in December of that year. There is some indication that the valve arrangement was problematic at high engine speeds, but the engines were displayed at the next two Salons in November 1921 and December 1922. No applications are known for the 12F or the 24G, which were too large for almost all aircraft. It is unlikely that more than a few of these engines were built.

Lorraine 12Eb no mags

A direct-drive 12E-series engine with exposed valves and overhead camshafts. Unseen are the magnetos positioned at the rear of the engine.

While enduring the rough start with the first generation of W engines, Barbarou had already designed the second generation—starting with the 12E-series. The first engine in this series was the 12Ew, which was derived from the 370 hp (276 kW) Lorraine 12D (V-12) and conceived to fill the power gap between that engine and the 500 hp (373 kW) 12F. The 12Ew was similar in layout to the 12F, but had a completely different valve arrangement. The exposed valves for each cylinder bank were actuated via rockers by a single overhead camshaft. The camshaft was driven by the crankshaft via bevel gears and a vertical shaft at the rear of the engine. It appears that the two magnetos were initially located at the front of the engine but later relocated to the rear of the engine. The engine had a compression ratio of 5.5 to 1. The propeller was attached directly to the crankshaft without any gear reduction.

The Lorraine 12Ew had a 4.72 in (120 mm) bore and a 7.09 in (180 mm) stroke. The engine displaced 1,491 cu in (24.4 L) and produced 420 hp (313 kW) at 1,800 rpm. The 12Ew was 54.1 in (1.37 m) long, 47.6 in (1.21 m) wide, and 44.8 in (1.14 m) tall. The engine weighed around 860 lb (390 kg). The 12Ew was first run around late 1919, but development was slowed due to work on other engines and other projects. The 12Ew was used in a few aircraft, and the engine was developed into the 12Eb.

The Lorraine 12Eb was dimensionally the same as the 12Ew, but it had a compression ratio of 6.0 to 1 and produced 450 hp (336 kW) at 1,850 rpm. The engine weighed 822 lb (373 kg). The 12Eb was first run in late 1922 or early 1923, and 30 test engines were built in 1923. The 12Eb quickly proved itself to be a successful engine. In March 1924, the 12Eb was the most economic engine at an endurance competition (Concours de Moteurs de Grande Endurance) held at Chalais-Meudon, near Paris. The engine operated for a total of 410 hours at 1,850 rpm. During that time, three cylinders were replaced due to water leaks.

Lorraine 12Eb museaum

A 12Eb engine with the magnetos driven from the front of the engine. Power from the magnetos was taken to the distributors, which were driven by the back of the left and right cylinder bank camshafts. (Pline image via Wikimedia Commons)

12Eb production started in late 1924, and approximately 150 engines were built in 1925. From 1924 to 1927, a number of licenses were purchased by other countries to manufacture the 12Eb: CASA and Elizalde in Spain; SCAT in Italy; FMA in Argentina; Hiro, Nakajima, and Aichi in Japan; PZL in Poland; Škoda and ČKD in Czechoslovakia; and IAR in Romania. The Blériot-SPAD S.61 fighter, the Breguet 19 light bomber, and the Potez 25TOE reconnaissance bomber were the 12Eb’s primary applications.

In 1925, a geared version of the 12Eb was developed, and it was designated 12Ed (sometimes referred to as 12Ebr). The planetary gear reduction turned the propeller at .647 times crankshaft speed. At 59.9 in (1.52 m), the 12Ed was 5.8 in (.15 m) longer than the direct-drive engine. Engine weight also increased 86 lb (39 kg) to 908 lb (412 kg). The 12Ed produced the same 450 hp (336 kW), but this was achieved at 1,900 engine rpm and 1,226 propeller rpm. The main application for the 12Ed was the CAMS 37 reconnaissance flying boat.

Lorraine 12Ed

The 12Ed engine with a propeller gear reduction was the same basic engine as the 12Eb. The early engines had a smooth gear reduction housing, but ribs were added later for extra strength.

The 12Ee debuted in 1926. This engine was basically a 12Eb with its compression ratio increased to 6.5 to 1. The 12Ee produced 480 hp (358 kW) at 2,000 rpm and had a maximum output of 510 hp (380 kW). The engine weighed 846 lb (383 kg). The 12E-series engines were used in the FBA-21 flying boat and Villiers IV seaplane to set numerous seaplane payload and distance records. Lorraine built around 5,500 E-series W-12 engines, and licensed production added another 1,775, for a total of approximately 7,275 engines. In all, the 12E-series engines were used in around 24 countries.

In December 1926, a Lorraine W-18 engine was displayed at the salon de l’Aviation in Paris. The 18-cylinder engine was designated 18K, and it was based on the E-series. The engine had been under development by Barbarou since at least 1923. The 18K had individual cylinders, rather than the paired units used on the E-series. The cylinder banks had an included angle of 40 degrees. Each of the cylinder banks had two carburetors, with each carburetor feeding three cylinders. Otherwise, the induction system was similar to that used on the 12E, including the two barrel carburetors on the left side of the engine for the left and center cylinder banks. The 18K had a compression ratio of 6.0 to 1, and its crankshaft was supported by seven main bearings.

The Lorraine 18K had the same 4.72 in (120 mm) bore and a 7.09 in (180 mm) stroke as the 12E-series engines. The W-18 engine displaced 2,236 cu in (36.6 L) and weighed around 1,287 lb (584 kg). The 18Kb was the direct drive variant that produced 650 hp (485 kW) at 2,000 rpm. The engine was 79.2 in (2.01 m) long, 36.2 in (.92 m) wide, and 43.3 in (1.10 m) tall.

Lorraine 18K

The 18K engine had the same construction as the 12E engines but used individual cylinders. Note that each carburetor fed two inductions pipes—one supplied the left cylinder bank and the other the center bank. The two one-piece magneto/distributor units are driven from the camshaft drive.

A version with a propeller gear reduction was designated 18Kd. The 18Kd turned the propeller at .647 times crankshaft speed and produced up to 785 hp (585 kW) at 2,500 rpm, but its continuous rating was the same as the 18Kb. With a total length of 83.5 in (2.12 m), the 18Kd was 4.3 in (109 mm) longer than the direct drive variant. The 18Kd weighed 1,365 lb (619 kg).

The 18Kd underwent official trials in mid-February 1927, and it was selected for the single-engine Amiot 122 bomber. The 18K may have been installed in other prototype aircraft, but the Amiot 122 was its only production application. A total of approximately 100 18Kb and 18Kd engines were made, and it was not considered a commercial success.

In 1928, Barbarou and Lorraine developed the third generation of W-12 engines, known as 12Fa Courlis. This was a reuse of the “12F” designation that was first applied in 1918. The F-series Courlis engines had a crankcase similar to that of the E-series, but the cylinder bank was a monobloc aluminum casting with enclosed valves. The steel cylinder liners were screwed into the cylinder banks, and the engine’s compression ratio was 6.0 to 1. Compared to the 12E, the cylinder bore diameter was increased, and the stroke length was decreased. Each cylinder had two intake and two exhaust valves, all actuated by a single overhead camshaft. The intake and exhaust ports were on the same side of the cylinder bank, and the carburetors mounted directly to the cylinder bank. The crankshaft was supported by five main bearings.

The Lorraine 12Fa Courlis had a 5.71 in (145 mm) bore and a 6.30 in (160 mm) stroke. The engine displaced 1,944 cu in (31.7 L) and produced 600 hp (447 kW) at 2,000 rpm. Sources indicate that the engine was capable of 765 hp (570 kW) at 2,400 rpm. Without gear reduction, the 12Fa Courlis was 62.2 in (1.66 m) long, 44.9 in (1.14 m) wide, 41.7 in (1.06 m) tall, and weighed 933 lb (423 kg). While the .647 propeller gear reduction did not increase the engine’s length by any noteworthy value, it did add 59 lb (27 kg), resulting in a weight of 992 lb (450 kg).

Lorraine 12Fa

With its enclosed valves and monobloc cylinder banks, the 12Fa Courlis was a modern engine design when it appeared in 1929. The gear reduction mounted to the crankcase in place of the direct-drive propeller shaft housing. The rest of the engine, including the crankshaft, was the same between the direct drive and geared variants.

The 12Fa Courlis was first run around 1928 and was tested by the Ministére de l’Air (French Air Ministry) from 10 to 17 June 1929. During the test, 52 hours were run at 2,000 rpm. In July 1929, the 12Fa made its public debut at the Olympia Aero Show in London. The French authorities officially approved the engine for service on 21 August 1929. The 12Fa was installed in a Potez 25 for engine development tests, which were conducted in 1930.

Developed in 1930, the 12Fb Courlis had a simplified induction system compared to the 12Fa. The 12Fb Courlis had a single, three-barrel carburetor mounted at the rear of the engine. Three separate intake manifolds extended from the carburetor, with one manifold connecting to each cylinder bank. The engine had cross-flow cylinder heads, with the exhaust ports on the side opposite of the intake ports. The 12Fb had the same basic specifications as the 12Fa, but fuel delivery issues initially reduced its rating to 500 hp (372 kW) at 1,900 rpm. However, continued development of the 12Fb soon brought its power up to 600 hp (447 kW) at 2,000 rpm, the same as the 12 Fa. Although installed in a few prototypes, the 12Fb did not power any production aircraft. By the early 1930s, air-cooled radial engines were increasing in popularity for transports and liquid-cooled V-12 engines for fighters. The Lorraine F-series Courlis did not find the success of the E-series. Around 30 F-series Courlis engines were built.

Lorraine 12Fb

The 12Fb had a simplified induction system with one carburetor and three intake manifolds. However, unequal fuel distribution was an issue.

Around 1932, an updated 12Eb was designed that incorporated some features from the 12F-series. Designated 12E Hibis, the engine used aluminum four-valve heads similar to those employed on the 12F engines. The Hibis had a 4.80 in (122 mm) bore and a 7.09 in (180 mm) stroke. The engine’s total displacement was 1,541 cu in (25.3 L), and it produced 500 hp (373 kW) at 2,000 rpm. While the engine was proposed around 1932, it is not clear if any were actually produced. The Hibis had disappeared by 1934.

In 1930, Barbarou created the 18-cylinder Lorraine 18Ga Orion. This W-18 engine combined the configuration of the 18K and the improved construction techniques of the F-series Courlis engines. The 18Ga had three monobloc cylinder banks set at 40 degrees. Each bank had six cylinders with a single overhead camshaft that operated the four valves per cylinder. The left and right cylinder banks had their intake and exhaust ports on their outer side. The carburetors were also mounted directly to the outer side of the cylinder bank. The center cylinder banks had a crossflow head with the carburetor and intake ports on the left side and the exhaust port on the right side. The crankshaft was supported by seven main bearings, and the engine had a .647 planetary gear reduction. It does not appear that there was a direct-drive variant.

Lorraine 18Ga

The 18Ga Orion combined the 18-cylinder 18K engine with the modern construction of the 12F-series. Note that the outer cylinder banks have intake and exhaust ports on the same side, while the center cylinder bank has intake and exhaust ports on opposite sides.

The 18Ga Orion had a 4.92 in (125 mm) bore and a 7.09 in (180 mm) stroke. The engine displaced 2,426 cu in (39.8 L) and produced 700 hp (522 kW) at 2,100 rpm and 870 hp (649 kW) at 2,500 rpm. The W-18 engine was 83.1 in (2.11 m) long, 36.6 in (.93 m) wide, and 43.7 in (1.11 m) tall. The engine weighed 1,252 lb (568 kg). The 18Ga completed a 50-hour type test prior to its public debut at the salon de l’Aviation in Paris in November 1930. The engine was used in at least one prototype aircraft, the Amiot 126 bomber. The 18Ga did not enter production, and only around 10 engines were built.

In November 1934, a supercharged version of the 18G Orion was displayed at the salon de l’Aviation in Paris. An updraft carburetor fed the gear-driven, centrifugal supercharger that was mounted to the rear of the engine. Three intake manifolds delivered the air and fuel mixture to the cylinder banks, just like the 12Fb engine. The revised cylinder banks included four valves per cylinder that were actuated by dual overhead camshafts. Each camshaft pair was driven by a vertical shaft at the rear of the engine. The supercharged 18G produced 1,050 hp (783 kW) at 2,150 rpm, but no additional specifications have been found.

A few 12E-series engines are preserved in various museum. No Lorraine F-series, 18-cylinder, or 24-cylinder engines are known to exist.

Lorraine 18G supercharged

The supercharged 18G Orion that was debuted in November 1934. Note the appearance of the new cylinder banks, which included four valves per cylinder.

Lorraine-Dietrich by Sébastien Faurès Fustel de Coulanges (2017)
Aerosphere 1939 by Glenn D. Angle (1940)
Les Moteurs a Pistons Aeronautiques Francais Tome I by Alfred – Bodemer and Robert Laugier (1987)
Le moteur Lorraine 12 Eb de 450 ch by Gérard Hartmann (undated)
Moteur “Lorraine” 450 C.V. 12 Cylinders en W by Société Lorraine (circa 1925)
Les Moteurs Lorraine by Société Générale Aéronautique (circa 1932)
Moteur “Lorraine” 600 CV (Type 12 Fa.) by Société Lorraine (10 November 1929)

Lun MD-160 Ekranoplan cruiser

Lun-class / Spasatel Ekranoplans

By William Pearce

In March 1980, the Soviet government envisioned a fast-attack force utilizing missile-carrying ekranoplans. An ekranoplan (meaning “screen plane”), also known as wing-in-ground effect (WIG) or ground-effect-vehicle (GEV), is a form of aircraft that operates in ground effect for added lift. The machines typically operate over water because of their need for large flat surfaces.

Lun MD-160 Ekranoplan moored

The missile-carrying Lun ekranoplan at rest on the Caspian Sea. The craft exhibits worn paint in the undated photo. Note the gunner’s station just below the first missile launcher. A Mil Mi-14 helicopter is in the background.

When the missile-carrying ekranoplan was being considered, the huge KM (Korabl Maket) ekranoplan was being tested, and testing was just starting on the three production A-90 Orlyonok transport ekranoplans. Known as Project 903, the missile-carrying Lun-class ekranoplans would be built upon the lessons learned from the earlier machines. The word “lun” (лунь) is Russian for “harrier.” An order for four examples was initially considered, with the number soon jumping to 10 Lun-class machines.

The first Lun-class ekranoplan was designated S-31, with some sources stating the designation MD-160 was also applied. Most sources referred the craft simply as “Lun.” The Lun was designed by Vladimir Kirillovykh at the Alekseyev Central Hydrofoil Design Bureau in Gorky (now Nizhny Novgorod), Russia. The new craft differed from previous ekranoplans by not having dedicated cruise engines.

Lun MD-160 Ekranoplan at speed

The Lun at speed traveling over the water’s surface. Note the contoured, heat-resistant surface behind each missile tube to deflect the exhaust of the launching missile. The large domes on the tail are evident in this image.

The Lun’s all-metal fuselage closely resembled that of a flying boat with a stepped hull. Mounted just behind the cockpit were eight Kuznetsov NK-87 turbojets, each capable of 28,660 lbf (127.5 kN) of thrust. The engines were mounted in sets of four on each side of the Lun. The nozzle of each jet engine rotated down during takeoff to increase the air pressure under the Lun’s wings (power augmented ram thrust). This helped the craft rise from the water’s surface and into ground effect. The nozzles were positioned straight back for cruise flight.

Lun MD-160 Ekranoplan ship

With flaps down, the Lun passes by a Soviet Navy ship. The rear gunner’s position is just visible at the rear of the craft.

The mid-mounted, short span wings had a wide cord and an aspect ratio of 3.0. Six large flaps made up the trailing edge of each wing, with the outer flaps most likely operating as flaperons (a combination flap and aileron). The tip of each wing was capped by a flat plate that extended down to form a float. A single hydro-ski was positioned under the fuselage, where the wings joined. The hydraulically-actuated ski helped lift the craft out of the water as it picked up speed. A swept T-tail with a split rudder at its trailing edge rose from the rear of the fuselage. Radomes in the tail’s leading edge housed equipment for navigational and combat electronics. The large, swept horizontal stabilizer had large elevators mounted to its trailing edges.

Lun MD-160 Ekranoplan cruiser

Looking more like an alien ship out of a science fiction movie than a cold-war experiment, the Lun was an impressive sight. Note the chines on the bow to help deflect water from the engines.

Mounted atop the Lun were three pairs of angled missile launchers. No cruise engines were mounted to the Lun’s tail over concerns that the engines would cut out when they ingested the exhaust plume from a missile launch. The launchers carried the P-270 (3M80) Moskit—a supersonic, ramjet-powered, anti-ship cruise missile. The P-270 traveled at 1,200 mph (1,930 km/h) and had a range of up to 75 miles (120 km). The belief was that the Lun-class ekranoplans would be able to close in on an enemy ship undetected and launch the P-270 missile, which would be nearly unstoppable to the enemy ships. The Lun also had two turrets, each with two 23 mm cannons. One turret was forward-facing and positioned below the first pair of missile launchers. The second turret was rear-facing and positioned behind the Lun’s tail.

Lun MD-160 Ekranoplan Kaspiysk

View of the Lun in March 2009 as it sits slowly deteriorating at the Kaspiysk base on the Caspian Sea. The special dock was made for the Lun. The dock was towed out to sea and submerged to allow the Lun to either float free for launch or be recovered.

The Lun had a wingspan of 144 ft 4 in (44.0 m), a length of 242 ft 2 in (73.8 m), and a height of 62 ft 11 in (19.2 m). The craft had a cruise speed of 280 mph (450 km/h) and a maximum speed of 342 mph (550 km/h). Operating height was from 3 to 16 ft (1 to 5 m), and the Lun had an empty weight of 535,723 lb (243,000 kg) and a maximum weight of 837,756 lb (380,000 kg). The craft had a range of 1,243 miles (2,000 km) and could operate in seas with 9.8 ft (3 m) waves. The Lun had a crew of 15 and could stay at sea for up to five days.

The Lun was launched on the Volga River on 16 July 1986. Operating from the base at Kaspiysk, Russia, testing occurred on the Caspian Sea from 30 October 1989 to 26 December. By that time, plans for the Lun-class of missile-carrying ekranoplans had faded, and the decision was made that only one of the type would be built. The Lun was withdrawn from service sometime in the 1990s and stored at Kaspiysk, where it remains today. In 2002, there was talk of reviving the missile-carrying ekranoplan, but no action was taken.

Lun MD-160 Ekranoplan Kaspiysk igor113

An interesting view of the Lun sitting at Kaspiysk in late-2009. Note the downward angle of the jet nozzles, and the flaps appear to be disconnected. The elements have taken a toll on the ekranoplan. (igor113 image)

The second machine (S-33), which was about 75-percent complete, was converted to serve as a Search and Rescue (SAR) craft. This decision was in part due to the loss of the K-278 Komsomolets submarine on 7 April 1989. A fire caused the loss of the submarine, and 42 of the 69-man crew died, many from hypothermia as they awaited rescue. This accident illustrated the need for a fast-response SAR craft.

Spasatel Ekranoplan Volga

The Spasatel in mid-2014 at the Volga Shipyard with a protective wrap to help preserve the craft. The wings and horizontal stabilizers are resting on the ekranoplan’s back. Note the machine’s reinforced spine. (rapidfixer image)

For its new purpose, S-33 was named Spasatel for “Rescuer.” Conversion work was started around 1992. The Spasatel had the same basic configuration as the Lun but had a reinforced spine and an observation deck placed atop its tail. The Spasatel possessed the same dimensions and performance as the Lun. However, sources state that the Spasatel would fly out of ground effect. For sea search missions, the craft would fly at an altitude of 1,640 ft (500 m), and it had a ceiling of 24,606 ft (7,500 m). The Spasatel had a range of 1,864 miles (3,000 km).

Spasatel Ekranoplan Volga Andrey Orekhov

The Spasatel seen in late 2018 at the Volga / Krasnoye Sormovo Shipyard in Nizhny Novgorod. The craft has been outside and exposed to the elements since 2016. Note the observation deck incorporated into the tail. (Андрей Орехов / Andrey Orekhov image)

The SAR ekranoplan would be quickly altered based on its mission. The Spasatel could carry up to 500 passengers, or temporarily hold 800 people for up to five days waiting for rescue. As a hospital ship, 80 patients could be treated on the Spasatel. A tank with 44,092 lb (20,000 kg) of fire retardant could be mounted atop the Spasatel for fighting fires on ships or oil platforms. Or, a submersible with space for 24 people could be mounted on the Spasatel for responding to submarine accidents. The Spasatel could even respond to oil spills and lay out 9,843 ft (3,000 m) of barriers. Even more ambitious was the noble plan to have several Spasatel ekranoplans in-service around the world ready to respond to any call of marine distress at a moment’s notice.

The Spasatel was about 80-percent complete when work was halted in the mid-1990s due to a lack of funds. In 2001, there was renewed hope that the Spasatel would be completed, but again, no money was forthcoming. The Spasatel was housed in the construction building at the Volga Shipyard until 2016, when it was moved outside. In 2017, there was again some hope that the Spasatel would be completed, now for SAR missions in the Arctic. Under this plan, work on the Spasatel would continue from 2018 until its completion around 2025. However, it does not appear that any work has been done, and the Spasatel continues to deteriorated as it sits exposed to the elements.

Spasatel Ekranoplan Model

Spasatel model from 2017 depicting its new purpose as an artic rescue craft. It does not appear that any work has been performed on the actual machine, but who knows what the future may hold. (Valery Matytsin/TASS image via The Drive)

Soviet and Russian Ekranoplans by Sergy Komissarov and Yefim Gordon (2010)
WIG Craft and Ekranoplan by Liang Lu, Alan Bliault, and Johnny Doo (2010)

Alexeyev A-90 Orlyonok top

Alexeyev SM-6 and A-90 Orlyonok Ekranoplans

By William Pearce

Rostislav Alexeyev (sometimes spelled Alekeyev) of the Central Hydrofoil Design Bureau (CHDB or Tsentral’noye konstruktorskoye byuro na podvodnykh kryl’yakh / TsKB po SPK) had been working out of the Krasnoye Sormovo Shipyard in Gorky (now Nizhny Novgorod), Russia since the 1940s. In the 1950s, Alexeyev began experimental work with ekranoplans (meaning “screen planes”), also known as wing-in-ground effect (WIG) or ground-effect-vehicle (GEV). His work led to the construction of the massive, experimental KM (Korabl Maket or ship prototype) ekranoplan in the mid-1960s.

Alexeyev SM-6 rear

The SM-6 was a 50-percent scale proof-of-concept vehicle for the A-90 Orlyonok ekranoplan. First flown in 1971, testing of the SM-6 continued until the mid-1980s.

As work on the KM was underway, the Soviet Navy expressed interest in a troop transport ekranoplan, and Alexeyev had started design studies of such a craft as early as 1964. In 1966, the decision was made to construct a 50-percent scale test model of the troop transport. The test ekranoplan was designated SM-6 (samokhodnaya model’-6 or self-propelled model-6).

The SM-6 had a flying boat-style stepped hull that was made of steel and aluminum. The two-place, side-by-side cockpit was near the front of the machine and covered with a large canopy. Two hydro-skis were placed under the hull: one under the nose (bow) and one under the wings. The hydraulically-actuated skis helped lift the craft out of the water as it picked up speed.

Alexeyev SM-6 square

An undated image of the SM-6 on display at Lenin Square in Kaspiysk, Russia. The ekranoplan has since been removed, and its fate is unknown. However, another undated image shows the its derelict fuselage (hull) in a sorry state.

Mounted in the SM-6’s nose were two Milkulin RD-9B jet engines, each of which produced 4,630 lbf (20.6 kN) of thrust. The inlets for the engines were in the upper surface of the nose, and the nozzles protruded out the sides of the SM-6, just behind and below the cockpit. For takeoff, the jet nozzle of each engine was rotated down to increase air pressure under the craft’s wings (power augmented ram thrust). In cruise flight, the nozzles were pointed back for forward thrust.

The low-mounted wing had a short span and a wide cord, and had an aspect ratio of 2.8. Five flaps were attached along each wing’s trailing edge. The outer flaps most likely acted as flaperons, a combination flap and aileron, but definitive proof has not been found. The tip of each wing extended down to form a float. A large vertical stabilizer extended from the rear of the craft. A rudder was positioned on the trailing edge of the vertical stabilizer. When the SM-6 was on the water’s surface, the bottom part of the rudder was submerged and helped steer the craft. Mounted atop the tail was a 3,750 shp (2,796 kW) Ivchenko AI-20K turboprop engine driving a four-blade propeller that was approximately 12 ft (3.65 m) in diameter. Behind the engine and atop the tail was the large horizontal stabilizer with swept leading and trailing edges. Large elevators were incorporated into the trailing edges of the horizontal stabilizer.

Alexeyev A-90 Orlyonok top

The A-90 Orlyonok cruising above the Caspian Sea. The jet intakes positioned atop the bow helped reduce the amount of water ingested into the engines and kept the craft rather streamlined.

The SM-6 had a wingspan of 48 ft 7 in (14.8 m), a length of 101 ft 8 in (31.0 m), and a height of 25 ft 9 in (7.85 m). The craft had a cruise speed of 186 mph (300 km/h) and a maximum speed of 217 mph (350 km/h). Its operating height was from 2 to 5 ft (.5 to 1.5 m), and the SM-6 had a maximum weight of 58,422 lb (26,500 kg). The craft had a range of 435 miles (700 km) and could operate in seas with 3.3 ft (1.0 m) waves.

Construction of the SM-6 started in October 1966 at the Krasnoye Sormovo Shipyard. Insufficient funding caused some delays, and the SM-6 was not finished until 30 December 1970. At that time, the Volga Shipyard was established as an experimental production facility of the CHDB and operated out of the same plant in which the SM-6 was built. The CHDB was also renamed the Alekseyev Central Hydrofoil Design Bureau.

Alexeyev A-90 Orlyonok cargo

The entire front of the Orlyonok swung open to allow access to the cargo hold. A 22,708 lb (10,300 kg) BTR-60PB armored personnel carrier is seen loaded on the Orlyonok. Note the engine’s exhaust nozzle and the machine gun turret.

In July 1971, the SM-6 was transported about 53 miles (85 km) up the Volga River to Chkalovsk, Russia. Initial tests of the craft were conducted in August 1971 on the Gorky Reservoir. In early 1972, the SM-6 was successfully tested on ice and snow. In 1973, modifications were made that included mounting wheels to the hydro-skis. The wheels were used as beaching gear, allowing the SM-6 to power itself out of the water and onto land, or vice versa. Having proven itself as a fully functioning ekranoplan, the SM-6 was transferred to the Kaspiysk base on the Caspian Sea in late 1974. The SM-6 continued to undergo modifications and testing until the mid-1980s. At different points in its career, the SM-6 was marked as 6M79 and 6M80. After it was withdrawn from service, the SM-6 was displayed for a number of years at a public square (Lenin Square?) in Kaspiysk. The elements took a toll on the ekranoplan, and it was eventually removed from the square. The derelict remains of the SM-6 sat near the shore of the Caspian Sea for a time, and mostly likely, the machine was later scrapped.

Following the successful tests of the SM-6 in 1971, plans moved forward for constructing a full-scale, troop transport ekranoplan. The full-size ekranoplan was known as the A-90 Orlyonok (Eaglet) or Project 904. Although twice its size, the Orlyonok had mostly the same configuration as the SM-6.

Alexeyev A-90 Orlyonok front

The Orlyonok’s beaching gear allowed the craft to propel itself out of the water and onto a hard surface. The turning arc of the nose wheel has not been found, but with the main wheels under the wing, the Orlyonok may have been able to turn rather sharply on land.

Mounted in the Orlyonok’s nose (bow) were two Kuznetsov NK-8-4K jet engines that provided 23,149 lbf (103.0 kN) of thrust each. Just behind the craft’s cockpit was a turret with two 12.7-mm (.50-Cal) machine guns. The entire nose of the Orlyonok, including its cockpit, swung open to the right a maximum of 92 degrees. A set of folding ramps allowed for direct entry into the machine’s cargo hold, which was 68 ft 11 in (21.0 m) long, 9 ft 10 in (3.0 m) wide, and 10 ft 6 in (3.2 m) tall. The hold could carry 250 troops or 44,092 lb (20,000 kg) of equipment, including armored vehicles.

The beaching gear mounted to the hydro-skis consisted of a steerable, two-wheel nose unit and a ten-wheel main unit under the hull. The low-mounted wing had a short span and a wide cord, with an aspect ratio of 3.0. The trailing edge of the wing had flaperons at its tips with flaps spanning the rest of the distance. The tip of each wing extended down to form a float. A large vertical stabilizer extended from the rear of the craft. Mounted atop the tail was a 15,000 ehp (11,186 kW) Kuznetsov NK-12MK turboprop engine driving an eight-blade, contra-rotating propeller that was approximately 19 ft 8 in (6.0 m) in diameter. The Orlyonok was equipped with a full-range of navigational and combat electronics.

Alexeyev A-90 Orlyonok slow

At low speed, a fair amount of spray enveloped the Orlyonok. The circular markings on the sides of the craft designated over-wing access doors, which were actually rectangular.

The Orlyonok had a wingspan of 103 ft 4 in (31.5 m), a length of 190 ft 7 in (58.1 m), and a height of 52 ft 2 in (15.9 m). The craft had a cruise speed of 224 mph (360 km/h) and a maximum speed of 249 mph (400 km/h). Operating height was from 2 to 16 ft (.5 to 5.0 m). The Orlyonok had an empty weight of 220,462 lb (100,000 kg) and a maximum weight of 308,647 lb (140,000 kg). The craft had a range of 932 miles (1,500 km) and could operate in seas with 6.6 ft (2.0 m) waves.

The Orlyonok prototype was built at the Volga Shipyard and made its first flight in 1972, taking off from the Volga River. The craft was later disguised as a Tupolev Tu-134 airliner fuselage and transported by barge to the Kaspiysk base on the Caspian Sea for further testing. In 1975, the prototype was accidently beached on a rocky sandbar. The craft was able to power itself back into the water, but the hull was damaged and its structural integrity was compromised. The damage went undetected until the rear fuselage and tail broke off during a landing on rough seas. Alexeyev was onboard and took control of the crippled ekranoplan. Using full-power of the bow jet engines, Alexeyev as able to keep the open back of the hull above water and return to base. The authorities attributed the accident to a design deficiency and blamed Alexeyev, who was removed as the chief designer and reassigned to experimental work.

Alexeyev A-90 Orlyonok GKS-13

The Orlyonok prototype flies past a Soviet Navy ship on the Caspian Sea. Unlike the SM-6, the Orlyonok’s rudder did not extend into the water when the craft was on the sea.

The Russian Navy had been sufficiently impressed by the Orlyonok to order three production machines and a static test article. The damaged prototype was returned to the Volga Shipyard and completely rebuilt as the first production Orlyonok, S-21 (610), which was completed in 1978 and delivered to the Navy on 3 November 1979. The second Orlyonok, S-25 (630), was completed in 1979 and delivered on 27 October 1981. The final Orlyonok, S-26 (650), was completed in 1980 and delivered on 30 December 1981. Plans to produce an additional eight units were ultimately abandoned.

The three Orlyonoks were tested and operated for several years on the Caspian Sea. The captain and crew of S-21 took it upon themselves to test the machine to its limits. Away from witnesses and in the middle of the Caspian Sea, S-21 was flown out of ground effect and up to 328 ft (100 m) for an extended time. At that height, the ekranoplan was sluggish, unstable, and a challenge to fly, but positive control was maintained.

Alexeyev A-90 Orlyonoks

Two production Orlyonoks at Kaspiysk on the Caspian Sea. Note the open over-wing doors and the open engine access panel of the first machine.

By 1989, the three Orlyonoks had performed a total of 438 flights and 118 beachings. On 12 September 1992, S-21 was lost when a control malfunction coupled with pilot error caused it to rise to 130 ft (40 m) and stall. One member of the ten-man crew was killed, and S-21 was eventually sunk by the Navy—the cost of salvaging the craft was too high. Reportedly, the last Orlyonok flight was made by S-26 in late 1993, after which, the Orlyonoks fell into a state of disuse followed by disrepair.

In 1998, the Navy wrote off the two remaining Orlyonoks. Around 2000, S-25 was scrapped, but S-26 was somehow preserved. In 2006, S-26 was given to the Museum and Memorial Complex of the History of the Navy of Russia (Muzeyno-Memorial’nyy Kompleks Istorii Vmf Rossii) located on the Volga River in Moscow. The S-26 was demilitarized in 2007 and restored and installed at the museum in 2008. The Orlyonok design inspired other military and commercial ekranoplan design, but none were built.

Alexeyev A-90 Orlyonok 2008

Orlyonok S-26 shortly after it was put on display at the Naval museum in Moscow. The wheels of the beaching gear are visible, although it appears the main set is missing two wheels. Sadly, the condition of the impressive ekranoplan has deteriorated over the years. (Alex Beltyukov image via Wikimedia Commons)

Soviet and Russian Ekranoplans by Sergy Komissarov and Yefim Gordon (2010)
WIG Craft and Ekranoplan by Liang Lu, Alan Bliault, and Johnny Doo (2010)

Alexeyev KM rear

Alexeyev KM Ekranoplan (Caspian Sea Monster)

By William Pearce

Rostislav Alexeyev (sometimes spelled Alekeyev) was born in Novozybkov, Russia on 18 December 1916. On 1 October 1941, he graduated from the Gorky Industrial Institute (now Gorky Polytechnic Institute) as a shipbuilding engineer. Alexeyev was sent to work at the Krasnoye Sormovo Shipyard in Gorky (now Nizhny Novgorod), Russia. In 1942, Alexeyev was tasked to develop hydrofoils for the Soviet Navy, work that was still in progress at the end of World War II. However, there was sufficient governmental interest for Alexeyev to continue his hydrofoil studies after the war. This work led to the development of the Raketa, Meteor, Kometa, Sputnik, Burevestnik, and Voskhod passenger-carrying hydrofoils spanning from the late 1940s to the late 1970s.

Alexeyev SM-2

The SM-2 was the first ekranoplan that possessed the same basic configuration later used on the KM. The nozzle of the bow (booster) engine is visible on the side of the SM-2. The intake for the rear (cruise) engine is below the vertical stabilizer. Note the three open cockpits.

Alexeyev appreciated the speed of the hydrofoil but realized that much greater speeds could be achieved if the vessel traveled just above the water’s surface. Wings with a short span and a wide cord could be attached to a vessel to lift its hull completely out of the water as it traveled at high speed, allowing it to ride on a cushion of air. Such a craft would take advantage of the ground (screen) effect as air is compressed between the craft and the ground. In Russian, this type of vessel is called an ekranoplan, meaning “screen plane.” They are also known as wing-in-ground effect (WIG) or a ground-effect-vehicle (GEV), since the craft’s wing must stay near the surface and in ground effect. Because ground effect vehicles fly without contacting the surface, they are technically classified as aircraft. However, ground effect vehicles need a flat surface over which to operate and are typically limited to large bodies of water, even though they can traverse very flat expanses of land. Because they operate from water, ground effect vehicles are normally governed by maritime rules.

In the late 1950s, Alexeyev and his team began work on several scale, piloted, test machines to better understand the ekranoplan concept. The first was designated SM-1 (samokhodnaya model’-1 or self-propelled model-1) and made its first flight on 22 July 1961. The SM-1 was powered by a single jet engine and had two sets (mid and rear) of lifting wings. Lessons learned from the SM-1 were incorporated into the SM-2, which was completed in March 1962. The SM-2 had a single main wing and a large horizontal stabilizer. The craft also incorporated a booster jet engine in its nose (bow) to blow air under the main wing to increase lift (power augmented ram thrust). The SM-2 was demonstrated to Premier of the Soviet Union Nikita Khrushchev, who then lent support for further ekranoplan development to Alexeyev and his team.

Alexeyev SM-5

The SM-5 was a 25-percent scale version of the KM. The craft followed the same basic configuration as the SM-2 but was more refined. The structure ahead of the dorsal intake was to deflect sea spray.

Ekranoplan design experimentation was expanded further with the SM-3. The craft had very wide-cord wings and was completed late in 1962. That same year, Alexeyev began working at the Central Hydrofoil Design Bureau (CHDB or Tsentral’noye konstruktorskoye byuro na podvodnykh kryl’yakh / TsKB po SPK). In 1963, the next test machine, the SM-4, demonstrated that a good understanding of ekranoplan design had been achieved. Also in 1963, the Soviet Navy placed an order for a large, experimental ekranoplan transport known as the KM (Korabl Maket or ship prototype).

While the CHDB began design work on the KM, the SM-5 was built in late 1963. The SM-5 was a 25-percent scale model of the KM and was powered by two Mikulin KR7-300 jet engines. The craft had a wingspan of 31 ft 2 in (9.5 m), a length of 59 ft 1 in (18.0 m), and a height of 18 ft 1 in (5.5 m). The SM-5 had a takeoff speed of 87 mph (140 km/h), a cruise speed of 124 mph (200 km/h), and a maximum speed of 143 mph (230 km/h). Its operating height was from 3 to 10 ft (1 to 3 m), and the craft had a maximum weight of 16,094 lb (7,300 kg). The SM-5 could operate in seas with 3.9 ft (1.2 m) waves. Initial tests of the SM-5 were so successful that the decision was made to construct the KM without building a larger scale test machine. Sadly, the SM-5 was destroyed, and its two pilots were killed in a crash on 24 August 1964. During a test, a strong wind was encountered that caused the craft to gain altitude. Rather than reduce power, the pilot added power. The SM-5 rose out of ground effect and stalled.

Alexeyev KM at speed

The KM (Korabl Maket) at speed on the Caspian Sea. Note the “04” tail number and the spray deflectors covering the cruise engine intakes on the vertical stabilizer.

The KM’s all-metal fuselage closely resembled that of a flying boat with a stepped hull. Mounted just behind the cockpit were eight Dobrynin VD-7 turbojets, with four engines mounted in parallel on each side of the KM. Each VD-7 was capable of 28,660 lbf (127.5 kN) of thrust. The jet nozzle of each engine rotated down during takeoff to increase the air pressure under the craft’s wings. These engines were known as boost engines.

The shoulder-mounted, short span wings had a wide cord and an aspect ratio of 2.0. Two large flaps made up the trailing edge of each wing. The tip of each wing was capped by a flat plate that extended down to form a float. Two additional VD-7 turbojets were mounted near the top of the KM’s large vertical stabilizer. These engines were known as cruise engines and were used purely for forward thrust. A heat-resistant panel covered the section of the rudder just behind the cruise engines. At low speeds, the rudder extended into the water and helped steer the KM. Atop the vertical stabilizer was the horizontal stabilizer, which had about 20 degrees of dihedral. A large elevator was mounted to the trailing edge of the horizontal stabilizer.

Alexeyev KM top

The servicemen atop the KM help illustrate the craft’s immense size. Note the access hatches in the wings. This view also shows the ekranoplan’s large control surfaces. The nozzles of the left engines are in the down (boost/takeoff) position while the nozzles on the right are in the straight (cruise flight) position.

The KM had a wingspan of 123 ft 4 in (37.6 m), a length of 319 ft 7 in (97.4 m), and a height of 72 ft 2 in (22.0 m). The craft had a cruise speed of 267 mph (430 km/h) and a maximum speed of 311 mph (500 km/h). Operating height was from 13 to 46 ft (4 to 14 m), and the KM had an empty weight of 529,109 lb (240,000 kg) and a maximum weight of 1,199,313 lb (544,000 kg). The craft had a range of 932 miles (1,500 km) and could operate in seas with 11.5 ft (3.5 m) waves. The KM had a crew of three and could carry 900 troops, but the craft was intended purely for experimental purposes.

The KM was built at the Krasnoye Sormovo Shipyard in Gorky. Alexeyev was the craft’s chief designer and V. Efimov was the lead engineer. The KM was launched on the Volga River on 22 June 1966 and was subsequently floated down the river to the Naval base at Kaspiysk, Russia on the Caspian Sea. To keep the KM hidden during the move, its wings were detached, it was covered, and it was moved only at night. After arriving at the Kaspiysk base, the KM was reassembled, and sea-going trials started on 18 October 1966. V. Loginov was listed as the pilot, but Alexeyev was actually at the controls. At 124 mph (200 km/h), the KM rose to plane on the water’s surface but did not take to the air. Planning tests were continued until 25 October 1966. The early tests revealed that the KM’s hull was not sufficiently rigid and that engine damage was occurring due to water ingestion. Stiffeners were added to the hull, and plans were made to modify the engines.

Alexeyev KM front

While at rest, the KM’s water-tight wings added to the craft’s stability on the water’s surface. Note the far-left engine’s open access panels. Covers are installed in all of the engine intakes.

The first true flight of the KM occurred on 14 August 1967 with Alexeyev at the controls. The flight lasted 50 minutes, and a speed of 280 mph (450 km/h) was reached. Further testing revealed good handling characteristics, and sharp turns were made with the inside wing float touching the water. At one point, the KM was mistakenly flown over a low-lying island for about 1.2 miles (2 km), proving the machine could operate over land, provided it was very flat.

The KM was discovered in satellite imagery by United States intelligence agencies in August 1967. Rather baffled by the craft’s type and intended purpose, the Central Intelligence Agency (CIA) began to refer to the enormous machine as the “Kaspian Monster,” in reference to the KM designation. The “Kaspian Monster” name slowly changed to “Caspian Sea Monster,” which is how the craft is generally known today. The sole KM was painted with at least five different numbers (01, 02, 04, 07, and 08) during its existence. Some sources state the numbers corresponded to different developmental phases, while others contend that the numbers were an attempt to obscure the actual number of machines built.

Alexeyev KM rear

The KM, now with an “07” tail number, cruises above the water. Note the heat resistant panel on the rudder, just behind the exhaust of the cruise jet engines.

While the KM was being built, a second 25-percent scale model was constructed. The model was designated SM-8, and its layout incorporated changes made to the KM’s design that occurred after the SM-5 was built. Like the SM-5, the SM-8 was powered by two Mikulin KR7-300 jet engines. The craft had a wingspan of 31 ft 2 in (9.5 m), a length of 60 ft 8 in (18.5 m), and a height of 18 ft 1 in (5.5 m). The SM-8 had a cruise speed of 137 mph (220 km/h). Operating height was from 3 to 10 ft (1 to 3 m), and the craft had a maximum weight of 16,094 lb (8,100 kg). The SM-8 could operate in seas with 3.9 ft (1.2 m) waves. The craft was first flown in 1968 and tested over a grassy bank in June 1969. The SM-8 also served to train pilots for the KM.

Alexeyev SM-8

The SM-8 was a second 25-percent scale model of the KM and constructed after the loss of SM-5. Its configuration more closely matched that of the KM. The stack above the wings surrounded the intake for the front (booster) engine and deflected sea spray. The front engine was installed so that its exhaust traveled forward to the eight outlets (four on each side) behind the cockpit.

By the late 1960s, the KM had proven that the ekranoplan was a viable means to quickly transport personnel or equipment over large expanses of water. Alexeyev’s focus had moved to another ekranoplan project, the A-90 Orlyonok. By 1979, the KM had been modified by relocating the cruise engines from the vertical stabilizer to a pylon mounted above the cockpit. All engines were fitted with covers to deflect water and prevent the inadvertent ingestion of the occasional unfortunate seabird.

In December 1980, the KM was lost after an accident occurred during takeoff. Excessive elevator was applied and resulted in a relatively high angle of attack. Rather than applying power and correcting the pitch angle, the angle was held and power was reduced. A stall occurred with the KM rolling to the left and impacting the water. The crew escaped unharmed, but the KM was left to slowly sink to the bottom of the Caspian Sea. Reportedly, the craft floated for a week before finally sinking. Either the Soviets were done with the KM, or its immense size prevented reasonable efforts to salvage the machine. From the time it first flew, the KM was the heaviest aircraft in the world until the Antonov An-225 Mriya made its first flight on 21 December 1988. The KM is still the longest aircraft to fly. Experience gained from the KM was applied to the Lun-class S-31 / MD-160.

Alexeyev KM 1979

The KM as seen in 1979 with the cruise engines relocated from the vertical stabilizer to a pylon above the cockpit. A radome is mounted above the engines. All of the engines have been fitted with spray deflectors.

Soviet and Russian Ekranoplans by Sergy Komissarov and Yefim Gordon (2010)
WIG Craft and Ekranoplan by Liang Lu, Alan Bliault, and Johnny Doo (2010)