Category Archives: Marine

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)

Sources:
Soviet and Russian Ekranoplans by Sergy Komissarov and Yefim Gordon (2010)
WIG Craft and Ekranoplan by Liang Lu, Alan Bliault, and Johnny Doo (2010)
https://s1rus.livejournal.com/154716.html
https://www.thedrive.com/the-war-zone/15542/russia-supposedly-bringing-back-giant-ekranoplans-for-arctic-missions
http://iiaat.guap.ru/?n=main&p=pres_spasatel
https://en.wikipedia.org/wiki/Spasatel
https://igor113.livejournal.com/51213.html
https://igor113.livejournal.com/52174.html
https://igor113.livejournal.com/52878.html

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)

Sources:
Soviet and Russian Ekranoplans by Sergy Komissarov and Yefim Gordon (2010)
WIG Craft and Ekranoplan by Liang Lu, Alan Bliault, and Johnny Doo (2010)
https://aviationhumor.net/the-last-flight-of-the-soviet-beach-assault-ekranoplan-a-90-orlyonok/#
http://www.volga-shipyard.com/index.php?section=history&lang=eng

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.

Sources:
Soviet and Russian Ekranoplans by Sergy Komissarov and Yefim Gordon (2010)
WIG Craft and Ekranoplan by Liang Lu, Alan Bliault, and Johnny Doo (2010)
https://en.wikipedia.org/wiki/Rostislav_Alexeyev
https://en.wikipedia.org/wiki/Caspian_Sea_Monster
https://rtd.rt.com/stories/caspian-monster-ekranoplan-vessel/
https://www.theregister.co.uk/2006/09/22/caspian_sea_monster/

Napier-Deltic-T18-37K-Marine-Engine

Napier Deltic Opposed-Piston Diesel Engine

By William Pearce

In 1933, the British engineering firm D. Napier & Son (Napier) acquired licenses to produce the Junkers Jumo 204 and 205 aircraft engines. Napier sought to diversify and expand its aircraft engine business, and the company felt the two-stroke, opposed-piston, diesel engines would usher in an era of safe and fuel-efficient air travel. Napier made some modifications to the Jumo engines, but the internal components were mostly unchanged. The Jumo 204 was built as the Napier Culverin (E102), and the Jumo 205 was planned as the Napier Cutlass (E103). The Culverin was first run on 24 September 1934, but the engine garnered little interest and no orders. By 1936, after only seven Culverins were made and no Cutlasses, Napier halted further work on opposed-piston diesel aircraft engines. English Electric took over Napier in November 1942.

Napier-Deltic-E130-Three-cylinder-test-engine

The Napier E130 three-cylinder test engine that validated the triangular engine arrangement. Each of the engine’s crankshafts had a flywheel on the drive end (left). The six intake chamber openings are visible on the free (non-drive) end (right). Note the vertical coolant pipes on top of the engine. (Napier/NPHT/IMechE images)

In 1944, the British Admiralty desired to increase the survivability of the Motor Torpedo Boat (MTB). One of the main issues was that MTBs used gasoline engines. Gasoline liquid is highly flammable, and gasoline vapor is highly explosive. MTB safety would be improved if a switch to diesel engines could be made. Diesel fuel has non-explosive characteristics and a much higher flashpoint than gasoline. However, at the time, there were no suitable diesel engines to power MTBs.

Around 1945, Napier and other companies submitted proposals to the Admiralty for a light-weight, powerful, and compact 18-cylinder diesel engine. Napier’s new engine carried the company designation E130, and the design was influenced by their experience with the Junkers Jumo diesel engines, their work on the Culverin and Cutlass, and analyses of other Jumo six-cylinder engines captured during World War II. However, there is no mention of the Junkers Jumo 223 contributing to Napier’s engine design. In early 1946, the Admiralty selected the Napier design and issued a developmental contract that covered the construction of one single-cylinder test engine, one three-cylinder test engine, and six prototype 18-cylinder engines.

Napier-Deltic-drive-end-section

Section drawing from the drive end of a Deltic engine. The air chamber surrounds the intake end of the cylinder, and the exhaust manifolds are mounted to the outer sides of the engine. Note the rotation of the crankshafts. (Napier/NPHT/IMechE image)

Napier’s liquid-cooled, two-stroke engine used opposed-pistons, a design feature that eliminated many parts, required no cylinder head, improved thermal efficiency, and resulted in more power for a given size and weight. In an opposed-piston engine, each cylinder has two pistons that move toward each other to form a single combustion space near the center of the cylinder. Ports in the cylinder wall that are covered and uncovered by the pistons bring in air and allow exhaust gases to escape. The most unusual aspect of Napier’s design was that the engine was formed as an inverted triangle, with a crankshaft at each corner. Because of its triangular structure, the name Deltic was selected in reference to the Greek letter Delta, and the 18-cylinder engine was known as the Deltic D18 (or just 18). The triangular design resulted in a compact engine with a very rigid structure.

Design work on the Napier Deltic started under Ben Barlow, George Murray, and Ernest Chatterton, Chief Engineer of the Piston Engine Division at Napier. The project was initially overseen by Henry Nelson, with Herbert Sammons taking over in 1949. The Deltic engine formed an equilateral triangle with each of its three cylinder banks angled at 60 degrees. Cast aluminum crankcase housings were at each corner of the triangle, with the lower crankcase incorporating an oil sump and also serving as the engine’s base. Each cast aluminum cylinder bank was sandwiched between two crankcases via through bolts. The monobloc cylinder banks were identical, as were the upper two crankcases. However, various ancillary components were installed according to the casting’s position on the complete engine.

Napier-Deltic-18-Triangle-Case

The assembled cylinder banks and crankcases of an 18-cylinder Napier Deltic engine seen from the free end. Note the open space between the cylinder banks. The stadium (oval) ports are to the air chambers. The bushings visible in the upper crankcases, at the triangle’s corners, supported the shafts that drove the blower. (Napier/NPHT/IMechE image)

The forged-steel cylinder wet liners were open-ended and had a chrome-plated bore to reduce wear. Part of the bore was etched with small dimples to retain lubricating oil and reduce piston ring wear. The liner was approximately 32 in (813 mm) long and protruded some distance into the crankcases. The ends of the liner were notched to allow clearance for the swinging connecting rods. Near one end of the liner were 14 intake ports with a tangential entry to impart a swirling motion of the incoming air. The swirling air helped scavenge the cylinder through the nine exhaust ports near the other end of the liner. In each cylinder, one piston would cover and uncover the intake ports while the other piston would do the same for the exhaust ports. The exhaust ports were uncovered (opened) 34.5 degrees before the intake ports. Both sets of ports were uncovered (open) for 101.5 degrees, and the intake ports were uncovered (open) for 5.5 degrees after the exhaust ports were covered (closed). The placement of the intake and exhaust ports at opposite ends of the cylinder liner allowed for uniflow scavenging of the cylinder. The liners were shrink-fitted into the cylinder banks and secured by an annular nut on the intake side.

The two-piece pistons consisted of a cast aluminum outer body and a forged Y-alloy (nickel-aluminum alloy) inner member that held the wrist pin. The inner member was heat-shrunk to the outer piston body and secured by a large circlip. Oil flowed between the two pieces to cool the piston. Three compression rings were positioned just below the piston crown, and two oil scraper rings were located near the bottom of the piston skirt. The pistons were attached to fork-and-blade connecting rods, with the exhaust pistons mounted to the forked rods and the intake pistons mounted to the blade rods. The opposed pistons created a compression ratio of 17.5 to 1 (some sources say 15 to 1).

Napier-Deltic-assembly

Napier Deltic engine assembly, with phasing gear housings being built up in the lower right. At left is a completed phasing gear housing; note the two idler gears connecting the lower crankshaft to the central output shaft. Toward the center are Deltics in various stages of assembly. A completed engine without its blower installed is in the upper right. Note the opening in the center of the engine. (Napier/NPHT/IMechE image)

A two-piece phasing gear housing at the drive end of the engine contained the gears that connected the crankshafts to the main output shaft. The main output shaft was usually located at the center of the engine, but different phasing gear housings allowed for different output shaft locations. Each crankshaft was coupled to its drive gear via a short, flexible quill shaft. When viewed from the free (non-drive) end of the engine, the upper two crankshafts rotated clockwise and were connected to the main output shaft via one idler gear. The lower crankshaft rotated counterclockwise and was connected to the main output shaft via two idler gears. The idler gears could be repositioned to reverse the rotation of the output shaft. Each crankshaft was supported in its crankcase by seven main bearings, and each main bearing cap was secured by four studs and two transverse bolts. The crankshafts were phased so that the exhaust piston in each cylinder led the intake piston by 20 degrees. The reverse rotation of the lower crankshaft, and the crankshaft phasing was devised by Herbert Penwarden from the Admiralty Engineering Laboratory.

Via a quill shaft and bevel gears, each crankshaft also drove a camshaft for the fuel injection pumps. The camshaft was located in a housing bolted to the outer side of each cylinder bank, near its center. Each camshaft operated six fuel injection pumps, and each pump fed fuel to two injectors per cylinder. The timing of the pumps changed depending on engine RPM. The upper two crankshafts drove separate flexible drive shafts for the blower (weak supercharger). The driveshafts were positioned at the upper, inner corners of the engine triangle. They led to the opposite end of the engine and powered a single-stage, double-sided centrifugal blower. The impeller was 15.5 in (394 mm) in diameter and rotated at 5.72 times crankshaft speed, creating 7.8 psi of boost (.53 bar). The pressurized air from the blower was fed into a chamber that extended through each cylinder bank and that surrounded the intake ports in the cylinder liner. Exhaust gases were collected via a water-cooled manifold that attached to the outer side of each cylinder bank. The lower crankshaft drove a flexible drive shaft to power the engine’s two oil and two water pumps.

Napier-Deltic-T18-37K-sections-display

Basic sections of the Deltic (T18-37K) marine engine. From left to right are the blower section (turbo-blower in this case), D18-cylinder engine section, phasing gear housing, and the bi-directional gearbox. The Deltic was a powerful diesel engine for its size and weight. (Napier/NPHT/IMechE image)

When viewing the engine from the free end, the cylinder banks were designated as follows: left was Bank A; upper, horizontal was Bank B; and right was Bank C. The crankshafts were designated as follows: upper left was Crankshaft AB, upper right was Crankshaft BC, and lower was Crankshaft CA. The cylinder rows were numbered with Bank 1 at the free end, and subsequent banks were numbered consecutively with Bank 6 at the drive end. The Deltic D18’s firing order was Bank C cylinder 1 (C1), A6, B1, C5, A1, B5, C3, A5, B3, C4, A3, B4, C2, A4, B2, C6, A2, and B6.

The Napier Deltic had a 5.125 in (130 mm) bore and a 7.25 in (184 mm) stroke (x2). This gave each cylinder a displacement of 299 cu in (4.9 L), and the 18-cylinder engine displaced 5,384 cu in (88.2 L). The bare engine (without the bi-directional marine gearbox) had a maximum, 15-minute output of 2,730 hp (2,036 kW) at 2,000 rpm with a specific fuel consumption (sfc) of .380 lb/hp/hr (231 g/kW/h). The Deltic’s continuous rating was 2,035 hp (1,517 kW) at 1,700 rpm with a sfc of .364 lb/hp/hr (221 g/kW/h). With the bi-directional gearbox, the engine produced 2,500 hp (1,864 kW) at 2,000 rpm with a sfc of .415 lb/hp/hr (252 g/kW/h) and 1,875 hp (1,398 kW) at 1,700 rpm with a sfc of .395 lb/hp/hr (240 g/kW/h). The Deltic D18 was 105 in (2.67 m) long, 71.25 in (1.81 m) wide, and 80 in (2.03 m) tall. The bi-directional gearbox added another 36 in (.91 m). The engine weighed 8,860 lb (4,018 kg) without the bi-directional gearbox and 10,500 lb (4,763 kg) with it.

The single-cylinder test engine was designed from October to December 1946, with the three-cylinder engine following from January to May 1947. Testing of these engines started as soon as construction was completed. The three-cylinder engine represented just one row of a Deltic engine, but it demonstrated the validity of the components used in the triangular arrangement.

Napier-Deltic-D18-E130-Prototype

Free end of the 2,500 hp (1,864 kW) Deltic D18-1 (E130) prototype engine. Note the two intakes, one for each side of the double-sided blower. Each cylinder bank had two, large exhaust manifolds. The transverse bolts threaded into the main bearings can be seen on the side of the upper crankcase. (Napier/NPHT/IMechE image)

The first 18-cylinder Deltic Series I engine was assembled by March 1950. The engine was soon to be tested at Napier’s works in Acton, England; however, a cable broke as the engine was being mounted to the stand. It fell on the stand, damaging the engine and the test stand. Repairs were made, and engine began testing in April 1950. The 18-cylinder Deltic fired a cylinder every 20 degrees of crankshaft rotation, which resulted in smooth, nearly-constant output torque. Engine idle was around 600 rpm, and the Deltic demonstrated a gross mechanical efficiency of 85.5% at 2,000 rpm. In late 1951, two Deltics were installed in place of the three Mercedes-Benz MB 501 V-20 engines in a former German E-boat S-212 (redesignated Fast Patrol Boat P5212). By January 1952, the originally-contracted six Deltic D18 engines had been built. In 1953, an Admiralty 1,000-hr type test was completed and indicated the engine could run 2,000 hours between overhauls.

By 1954, Napier was offering a commercial version of the Deltic D18 Series I (E169). This was basically a de-rated engine. The commercial engine produced 1,900 hp (1,417 kW) at 1,500 rpm with a sfc of .363 lb/hp/hr (221 g/kW/h) and could operate for 5,000 hours between overhauls. In addition to a variety of marine applications, Deltic engines could also run power generation sets, water pumps, and be used to power traction motors for locomotives. Napier also built a nine-cylinder version with three banks of three cylinders. The Deltic 9 (E159/E165) displaced 2,692 cu in (44.1 L) and had a one-sided centrifugal blower but was otherwise of the same construction as the Deltic D18. It fired one cylinder for every 40 degrees of crankshaft rotation. Maximum output for the Deltic 9 was 1,250 hp (932 kW) at 2,000 rpm for the high-power version and 950 hp (708 kW) at 1,500 rpm for the commercial version. By late 1955, Deltic test and production engines had accumulated over 20,000 hours of operation.

Napier-Deltic-C18-5-Compound-Marine-Engine

The 5,500 hp (4,101 kW) compound Deltic C18 (E185) engine was the most powerful piston engine Napier ever built. Although it is covered, the intake can be seen in the upper part of the phasing gear housing. Exhaust was routed through the three-stage turbine, which powered the eight-stage compressor inside the engine’s triangle. (Napier/NPHT/IMechE image)

In 1956, Napier built a compound diesel engine known as the Deltic C18 (E185). Serious development of the C18 occurred after the Napier Nomad II compound diesel aircraft engine was cancelled in 1955. The Deltic C18 had an eight-stage (some sources say 12-stage, which was the same number of stages as used in the Nomad II) axial compressor positioned inside the engine triangle. The compressor was driven by a three-stage turbine, which was powered by the engine’s exhaust gases. The turbine was positioned in the normal blower position on the free end of the engine. A new phasing gear housing was constructed with an opening that allowed air into the center of the engine triangle and served as the inlet for the compressor. The Deltic C18 produced 5,500 hp (4,101 kW) at 2,000 rpm. The engine was 124 in (3.15 m) long, 65 in (1.65 m) wide, and 77 in (1.96 m) tall. The C18 weighed approximately 10,700 lb (4,853 kg). The engine was tested in 1957, but only one experimental C18 was built. While undergoing power tests, a connecting rod failed at 5,600 hp (4,176 kW). The rod came through the crankcase, but the damage was never repaired due to the Navy’s increased focus on gas turbine engines.

By 1956, Napier had introduced some minor changes as the Series II Deltic engines, but one major change was the addition of a turbo-blower. These engines were known as turbo-blown, and they were designated as the Deltic T18 (E171/E239). Exhaust gases were collected and fed into an axial-flow turbine mounted behind the blower. The turbine wheel was 18.04 in (458 mm) in diameter and helped turn the blower via a geared shaft. The turbine wheel turned at .756 times the speed of the blower impeller. The blower was still driven by the upper crankshafts, but it now turned at 8.266 times crankshaft speed. The turbo-blower created 19 psi (1.31 bar) of boost. The piston was redesigned and consisted of three-pieces: a Hidural 5 (copper alloy) crown that screwed onto an aluminum skirt to form the outer body, and a Y-alloy (nickel-aluminum alloy) inner member that held the wrist pin. A third scraper ring was added to the piston skirt. The compression ratio was increased to 17.9 to 1, and the engine used one fuel injector per cylinder. The Deltic T18 had an output of 3,100 hp (2,312 kW) at 2,100 rpm and 2,400 hp (1,641 kW) at 1,800 rpm. SFC was .414 lb/hp/hr (252 g/kW/h) and .404 lb/hp/hr (246 g/kW/h) respectively. The engine was 118 in (3.00 m) long, 75 in (1.91 m) wide, and 84 in (2.13 m) tall. The T18 weighed around 13,630 lb (6,183 kg) with the bi-directional gearbox and 11,050 lb (5,012 kg) without it. The turbo-blown nine-cylinder Deltic T9 (E172/E198) produced 1,100 hp (820 kW) at 1,600 rpm.

Napier-Deltic-T18-37K-Marine-Engine

The 3,100 hp (2,312 kW) turbo-blown Deltic T18-37K (E239) engine was most widely used in Motor Torpedo Boats. Note the exhaust manifolds leading to the turbine with its large intake at the rear of the engine. The short duct connecting the blower to the upper cylinder bank is visible. (Napier/NPHT/IMechE image)

More changes were incorporated into the Series III engines, which also introduced charge-cooling with the Deltic CT18 (E263) in 1966. For the CT18, a single drive shaft passed through the center of the engine to deliver power from the phasing gear housing to the turbo-blower. The shaft turned at 5.16 times crankshaft speed, and both the blower impeller and turbine wheel were mounted to the drive shaft. The single-sided blower impeller was relocated to behind the turbine wheel. A water-filled aftercooler was mounted before each opening of the engine’s three air compartments. The aftercooler dropped the charge temperature from 259° F (126° C) to 144° F (62°C). Pistons were again redesigned, with the Hidural 5 (copper alloy) crown bolting to the aluminum skirt. For the Deltic CT18, power increased to 3,700 hp (2,759 kw) at 2,100 rpm with a sfc of .403 lb/hp/hr (245 g/kW/h) and 2,750 hp (2,051 kW) at 1,800 rpm with a sfc of .395 lb/hp/hr (240 g/kW/h). By 1968, further development had increased the output to 4,000 hp (2,983 kW) at 2,100 rpm with a sfc of .401 lb/hp/hr (244 g/kW/h) and 3,000 hp (2,237 kW) at 1,800 rpm with a sfc of .399 lb/hp/hr (243 g/kW/h). The CT18 weighed 15,382 lb (6,977 kg) with its bi-directional gearbox.

As Napier declined in the late 1960s, English Electric moved Deltic production to the newly acquired Paxman Engine Division. The General Electric Company (GEC, not related to the US company General Electric / GE) purchased English Electric in 1968. What was once Napier basically closed in 1969. In 1975, GEC reformed Paxman Engine Division as Paxman Diesels Limited. Paxman continued to support Deltic engines, developing the CT18 to 4,140 hp (3,087 kW) in 1978 and reworking the mechanically-blown Deltic 9 for production as the D9-59K (E280) in the early 1980s. The D9-59K was constructed almost entirely with non-ferrous (non-magnetic) parts for mine-sweeper duties. In 2000, MAN acquired what used to be Paxman, and Rolls-Royce was awarded a contract to support Deltic engines in 2001. The contract was carried through until 2012, but it is not clear if the contract was extended beyond that year.

Napier-Deltic-CT18-42K-Charge-Cooled-engine

A 3,700 hp (2,759 kw) charge-cooled and turbo-blown Deltic CT18-42K (E263) engine. The turbine is located between the engine and the blower. Note the large, square aftercooler in the air duct between the blower and the engine. (Napier/NPHT/IMechE image)

Deltic engines powered a number of various MTBs, including the Royal Navy’s Dark-class (18 produced). Two 3,100 hp (2,312 kW) Deltic C18 turbo-blown engines powered each Nasty-class / Tjeld-class fast patrol boat (total of 49 built), which were designed in 1959 and put in service in 1960. These boats served with the navies of Norway, the United States, Greece, Germany, and Turkey. The boats had a top speed of 52 mph (83 km/h), and some were in service until the 1990s. Deltic engines powered Ton-class minesweepers (over 100 built) as well as the pulse generators for other minesweepers. Deltics were still being installed in new military boats during the 1980s, with the 1,180 hp (880 kW) Deltic T9-powered Hunt-class minesweepers (13 built) still in service. A few commercial vessels were also powered by Deltic engines—the largest installation was four 1,850 hp (1,380 kW) engines for the 513.5-ft (156.5-m) ore carrier Bahama King in 1958.

In 1955, two 1,650 hp (1,230 kW) Deltic D18-12 (E158) engines were used in the English Electric DP1, a prototype diesel-electric locomotive. The engines powered six English Electric EE829-1A traction motors that gave the locomotive 50,000 lbf (222.4 kN) of tractive effort. The DP1 proved successful, resulting in 22 British Rail Class 55 locomotives powered by Deltic D18-25 (E169) engines being built in the early 1960s. Called Deltics, these locomotives could exceed 110 mph (177 km/h) and were in service until the early 1980s. One 1,100 hp (919 kW) Deltic T9-29 (E172) engine was used in each of the smaller British Rail Class 23 locomotives, known as Baby Deltics. The engine powered four English Electric traction motors that gave the locomotive 47,000 lbf (209.1 kN) of tractive effort. The Baby Deltics entered service in 1959, but they were not as successful as their bigger counterparts due to shorter runs and frequent stops. All Baby Deltics were withdrawn from service by 1971.

Napier-Deltic-CT18-Charge-Cooled-cutaway

Cutaway view of a Deltic CT-18 charge-cooled and turbo-blown engine. Note the shaft through the center of the engine that powered the turbo-blower from the phasing gear. (Napier/NPHT/IMechE image)

Other Deltic designs included a 735 hp (548 kW) inline six-cylinder (E164/E197) with one bank of six cylinders and a 1,420 hp (1,059 kW) 15-cylinder (E162) with three banks of five cylinders, but these engines were not built. A 24-cylinder square engine (E260) with four crankshafts and four banks of six cylinders was also designed for an output of 5,400 hp (4,027 kW). The square engine design had much more in common with the Deltic than the Jumo 223, but it was not constructed. Including the nine-cylinder version, over 600 Deltic engines were made. A number of Deltic engines survive. Some are still operational in preserved boats or locomotives, allowing the unusual roar of the triangular two-stroke Deltic to still be heard. Others engines are in various museums, and a few are privately owned.

Note: In some cases, the Napier E number is one example of the type, with additional E numbers existing for similar engines with different configurations (marine vs rail applications). Around 100 E numbers were assigned to various Deltic designs.

Napier-Deltic-T9-33-Locomotive-Rraction-Engine

A 1,250 hp (932 kW) turbo-blown nine-cylinder Deltic T9-33 (E198) under test at Napier’s factory in Acton. The engine was similar to those used in the Baby Deltic Locomotives. Note the low position of the output shaft. (Napier/NPHT/IMechE image)

Sources:
– “The Napier Deltic Diesel Engine” by Ernest Chatterton, SAE Transactions Vol 64 (1956)
Opposed Piston Engines by Jean-Pierre Pirault and Martin Flint (2010)
Course Notes on the Deltic Engine Type T18-37K by D. Napier & Son Ltd. (December 1967)
– “Development of the Napier Deltic Charge Cooled Engine” by R. P. Taylor and C. H. Davison, Proceedings of the Institution of Mechanical Engineers Vol 183 (1968–69)
By Precision Into Power by Alan Vessey (2007)
Napier Powered by Alan Vessey (1997)
https://www.ptfnasty.com/ptfDeltic.html
http://www.npht.org/deltic/4579702653

Fairbanks Morse Diamond stress test

Fairbanks Morse Diamond Opposed-Piston Marine Engine

By William Pearce

In the early 1930s, Fairbanks Morse & Company (FM) took an interest in two-stroke, opposed-piston, diesel engines, and they acquired a license to produce a design originally developed by the German firm Junkers. In an opposed-piston engine, each cylinder has two pistons that move toward each other to form a single combustion space near the center of the cylinder. Ports in the cylinder wall bring in air and allow exhaust gases to escape. The opposed-piston design offers some advantages over conventional engines by having fewer parts, no cylinder head, improved thermal efficiency, and more power for a given size and weight.

Fairbanks Morse 38E 5.25

The Fairbanks Morse 38E5-1/4 had characteristics common to other 38-series opposed-piston engines and was a basis for the 24-cylinder Diamond engine. (Fairbanks Morse image)

FM used the information acquired from Junkers to develop its own line of opposed-piston diesel engines. One of the first opposed-piston engines produced by FM was the Model 38, which was a two-stroke vertical engine with two crankshafts linked initially by a gear train, which was soon replaced by a drive chain. In its 38A8 form, the engine had eight cylinders with an 8 in (203 mm) bore and a 10 in (254 mm) stroke (x2). The 38A8 displaced 8,042 cu in (131.8 L) and produced 1,200 hp (895 kW) at 720 rpm. In December 1934, the United States Navy ordered eight 38A8 engines—four each for the USS Plunger (SS-179) and USS Pollack (SS-180) Porpoise-class submarines. Problems with the 38A8s led to a redesign, ultimately creating the 38D8 engine.

In 1937, FM upgraded the 38D8 to produce more power. The drive chain linking the two crankshafts was replaced with a vertical shaft and bevel gears. The bore was increased by .125 in (3 mm) to 8.125 in (206 mm), and cylinders were added to create 9- and 10-cylinder engines. The new engine was designated 38D8-1/8. With the larger bore and 10 cylinders, the engine displaced 10,370 cu in (169.9 L) and produced 1,600 hp (1,193 kW) at 720 rpm. Approximately 1,650 38D8-1/8 engines were built during World War II. The engine was eventually offered with 4, 5, 6, 8, 9, 10, and 12 cylinders and with or without turbocharging. Although changes have been incorporated over the years, the FM OP 38D8-1/8 remains in production today.

In 1939, FM developed a scaled-down version of the 38D to be used as an auxiliary power unit. This engine was designated 38E5-1/4, and it had a 5.25 in (133 mm) bore and a 7.25 in (184 mm) stroke (x 2). The engine was available with three, five, or seven cylinders. The 7-cylinder 38E5-1/4 displaced 2,197 cu in (36.0 L) and produced 467 hp (348 kW) at 1,200 rpm. Around 630 38E5-1/4 engines were built during World War II.

Fairbanks Morse Diamond sectional

Sectional drawing of the Fairbanks Morse Diamond engine shows the arrangement of its four crankshafts and opposed-piston cylinders. The output shaft is drawn with a six-hole flange and is just below the center of the engine. (Fairbanks Morse image)

Based on the development of the Model 38-series, the Navy approached FM in early 1940 with a request to design and build a 3,000 hp (2,237 kW) opposed-piston engine for submarine use. With the prospect of war looming on the horizon, FM quickly went to work on the new engine design and assigned Robert Beadle as the program’s head engineer. The engine borrowed the basic cylinder design from the 38E5-1/4, but the engine was of a diamond configuration with a crankshaft at each corner. This gave the engine four banks of six opposed-piston cylinders resulting in a total of 24 cylinders.

The FM Diamond engine was of welded steel construction, with the crankcase and four cylinder banks forming a single unit. The lower and upper bank angles were 60 degrees. The left and right bank angles were 120 degrees. A cover concealed each crankshaft, and crankshaft removal allowed access to the cylinder liners. Each forged steel crankshaft was supported by seven main bearings.

The fork-and-blade connecting rods were made from steel forgings and then polished for added strength. The rods were drilled to deliver oil from the crankshaft to the wrist pin and to the underside of the piston crown for cooling. The pistons had a concave crown and formed a somewhat hemispherical combustion space when the two pistons came together. The two-piece pistons were made of cast steel with an aluminum wrist pin carrier.

The cylinder liners were made of forged steel and had a chrome-plated bore. A water jacket was pressed on each liner’s center section, where combustion occurred. Intake and exhaust ports were cast into the cylinder liners, and movement of the pistons covered and uncovered these ports. The upper and lower crankshafts were connected to the “exhaust” pistons that controlled the exhaust ports, and the left and right crankshafts operated the “intake” pistons controlling the intake ports. The crankshafts were phased so that the exhaust pistons (upper and lower crankshafts) led the intake pistons (left and right crankshafts) by about 15 degrees. This allowed for good cylinder scavenging, with the exhaust ports being uncovered (open) before the intake ports and with the intake ports remaining uncovered (open) for a short time after the exhaust ports had been covered (closed).

Fairbanks Morse Diamond stress test

The welded crankcase of the Diamond engine undergoing stress tests before final assembly. The crankshafts and pistons are installed, and the output shaft is visible just below the engine’s center. Note the mounting pads at the top of the engine for the two centrifugal blowers. The blowers fed air into the center of the engine via the two large holes. (Fairbanks Morse image)

The upper crankshaft drove two gear-driven centrifugal blowers (weak superchargers) mounted to the drive end of the engine. The blowers forced air into a central chest inside of the engine diamond. Four compartments, one for each bank, surrounded the intake end of the cylinders and supplied air from the chest. The intake ports in the cylinder liner were tangentially cast so that the incoming air initiated a swirling motion as it entered the cylinder. This swirl helped scavenge the cylinder of exhaust gases and mix the fuel once it was injected. The exhaust end of each cylinder was surrounded by an open passageway that led outside of the engine. A water-cooled exhaust manifold made of welded steel was attached to the side of the engine and collected the exhaust gases.

Each of the left and right crankshafts drove an upper and lower camshaft. The camshafts actuated individual fuel injector pumps for the single fuel injector in each cylinder. The fuel injector was located in the center of the cylinder liner. Fuel was injected into the cylinder at approximately 3,000 psi (207 bar). All of the crankshafts were geared to a single output power shaft, located 13.75 in (349 mm) below the engine’s absolute center. The left, right, and lower crankshafts were each connected to the output shaft via one idler gear. The upper crankshaft was geared to the output shaft through three idler gears. The gears used herringbone teeth. Pressurized air fed through internal piping was used to start the engine.

In designing the engine, FM engineers spent over 6,000 man-hours on torsional vibration calculations alone. The FM Diamond engine was completed in 1942. It had a 5.25 in (133 mm) bore and a 7.25 in (184 mm) stroke (x 2). The engine’s total displacement was 7,533 cu in (123.4 L). The engine was 120 in (3.05 m) tall and 72 in (1.83 m) wide when bare, or 141.5 in (8.73 m) tall and 79.25 in (24.16 m) wide when mounted to its steel stand. Its length was approximately 90 in (27.43 m).

During testing, the Diamond engine produced 3,000 hp (2,237 kW) at 1,500 rpm with 6.88 psi (.47 bar) of scavenging pressure. At this power, the specific fuel consumption was .420 lb/hp/hr (255 g/kW/h). However, the engine experienced constant issues with excessive wear and carbon build-up in the intake and exhaust ports. The program was cancelled at the end of World War II. At the time of cancellation, the experimental Diamond engine had accumulated 2,032 hours of test running.

Fairbanks Morse Diamond test stand

The engine undergoing bench tests. Note the two centrifugal blowers providing air for scavenging and combustion. (Fairbanks Morse image)

Sources:
– “Development of Diamond Opposed-Piston Diesel Engine” by R. H. Beadle (discussion of “The Napier Deltic Diesel Engine”) SAE Transactions Vol 64 (1956)
Opposed Piston Engines by Jean-Pierre Pirault and Martin Flint (2010)
Diesels for the First Stealth Weapon: Submarine Power 1902–1945 by Lyle Cummins (2007)
Submarine Main Propulsion Diesels: NavPers 16161 (June 1946)
http://www.dieselduck.info/machine/01%20prime%20movers/fairbanks_morse/fairbanks_morse.htm