Author Archives: William Pearce

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/

Pratt Whitney R-2060 Yellow Jacket

Pratt & Whitney R-2060 ‘Yellow Jacket’ 20-Cylinder Engine

By William Pearce

Around 1930, the United States Army Air Corps (AAC) was interested in a 1,000 hp (746 kW), liquid-cooled aircraft engine. Somehow, the AAC persuaded Pratt & Whitney (P&W) to develop an experimental engine at its own expense to meet this goal. The engine was the R-2060 Yellow Jacket, and it carried the P&W experimental engine designation X-31. The “Yellow Jacket” name followed the “Wasp” and “Hornet” engine lines from P&W.

Pratt Whitney R-2060 Yellow Jacket

The Pratt & Whitney R-2060 Yellow Jacket was an experimental liquid-cooled engine. Note the annular coolant manifold around the front of the engine that delivered water to the water pumps.

While the R-2060 would be P&W’s first liquid-cooled engine, the company had experimented with liquid-cooled cylinders as early as 1928. In addition, many of P&W’s engineers had experience with liquid-cooled engines while working for other organizations—in particular, those workers who had helped develop liquid-cooled engines at Wright Aeronautical.

The R-2060 had a one-piece, cast aluminum, barrel-type crankcase. Attached radially around the crankcase at 72-degree intervals were five cylinder banks. The lowest (No. 3) cylinder bank was inverted and hung straight down from the crankcase. Each cylinder bank consisted of four individual cylinders arranged in a line. This configuration created a 20-cylinder inline-radial engine. Attached to the front of the crankcase was a propeller gear housing that contained a planetary bevel reduction gear. Mounted to the rear of the crankcase was the supercharger and accessory section.

The crankshaft had four throws and was supported by five main bearings. Mounted to each crankpin was a master connecting rod with four articulated connecting rods—a typical arrangement found in radial engines. Each individual cylinder was surrounded by a steel water jacket. Mounted atop each bank of cylinders was a housing that concealed a single overhead camshaft. The camshaft actuated the one intake valve and one exhaust valve in each cylinder. Each camshaft was driven from the front of the engine by a vertical shaft and bevel gears. Some of the camshafts drove magnetos at their rear. The magnetos fired the two spark plugs in each cylinder. The spark plugs were installed horizontally into the combustion chamber and placed on each exposed side of the cylinder. The camshaft housing on the lower cylinder bank was deeper and served as an oil sump.

Pratt Whitney R-2060 Yellow Jacket right

The 20-cylinder R-2060 was a fairly compact and light engine. Note the camshaft housings atop each cylinder bank and that the housing of the lower bank was deeper to serve as an oil sump. (Tom Fey image via the Aircraft Engine Historical Society)

Air was drawn into the downdraft carburetor mounted at the rear of the engine. Fuel was added, and the mixture then passed into the supercharger, which was primarily used to mix the air and fuel rather than provide boost. The air and fuel flowed from the supercharger through five outlets—one between each cylinder bank. The outlets were cast integral with the crankcase. Attached to each outlet was an intake manifold that branched into two sections, with each section branching further into two additional sections. The four pipes were then connected to the four cylinders of the cylinder bank. The exhaust ports were on the opposite side of the cylinder bank.

Cooling water flowed from the radiator into two inlets on an annular manifold mounted around the rear of the engine. The manifold had five outlets, one for each cylinder bank. Water flowed from the annular manifold into a pipe that ran along each cylinder bank. Branching off from the pipe were connections for each cylinder, with the mounting point near the exhaust port. The water passed by the exhaust port and through the water jacket, exiting near the intake port. The water from each cylinder was collected in another pipe that led to a smaller annular manifold mounted around the front of the engine. Two water pumps driven at the front of the engine took water from the front manifold and returned it to the radiator.

Pratt Whitney R-2060 Yellow Jacket left close

For each cylinder bank, the inlet for the intake manifold was cast into the crankcase. Unfortunately, the intake manifold did not provide equal distribution of the air and fuel mixture to the cylinders and caused the engine to run rough. The electric starter can be seen mounted on the left. (Tom Fey image via the Aircraft Engine Historical Society)

The Pratt & Whitney R-2060 Yellow Jacket had a 5.25 in (133 mm) bore and a 4.75 in (121 mm) stroke. Creating an oversquare (bore larger than the stroke) engine was not typical for P&W and was repeated only with the R-2000, which was derived from the R-1830 with minimal changes. However, the comparatively short stroke helped decrease the engine’s diameter. The R-2060 displaced 2,057 cu in (33.7 L) and was projected to produce 1,500 hp (1,119 kW) at 3,300 rpm. The Yellow Jacket was 70 in (1.78 m) long and 42 in (1.07 m) in diameter. The engine weighed 1,400 lb (635 kg).

Design work on the R-2060 was started in May 1931, and single-cylinder testing began in August of the same year. The engine was first run in 1932, and issues were soon encountered with rough running. The intake manifolds were of unequal lengths and caused inconsistent air and fuel distribution to the cylinders. Efforts to smooth out the engine’s operation by altering the firing order were tried but not successful. On its last test, the R-2060 achieved 1,116 hp (820 kW) at 2,500 rpm, but reaching 1,500 hp (1,119 kW) at 3,300 rpm was beyond what the engine could handle. The Yellow Jacket project was cancelled in late 1932 after accumulating just 35 hours of test running. Only one R-2060 engine was built.

Cancellation of the R-2060 allowed P&W to focus on the development of the air-cooled, two-row, 14-cylinder R-1830 Twin Wasp radial engine. The R-1830 became the most produced aircraft engine of all time, with 173,618 examples built. The sole R-2060 Yellow Jacket was preserved and is part of Pratt & Whitney’s Hangar Museum in East Hartford, Connecticut.

Pratt Whitney R-2060 Yellow Jacket rear

Rear view of the R-2060 illustrates the engine’s carburetor and supercharger housing. The annular manifold around the rear of the engine supplied cooling water to the five cylinder banks. (Kimble D. McCutcheon image via the Aircraft Engine Historical Society)

Sources:
– The Liquid-Cooled Engines of Pratt & Whitney by Kimble D. McCutcheon (presentation at the 2006 Aircraft Engine Historical Society Convention)
Development of Aircraft Engines and Fuels by Robert Schlaifer and S. D. Heron (1950)
The Engines of Pratt & Whitney: A Technical History by Jack Connors (2009)

Supermarine Spiteful RB518

Supermarine Spiteful and Seafang Fighters

By William Pearce

In 1942, the British Royal Aircraft Establishment at Farnborough and Supermarine Aviation were working on ways to improve the Spitfire fighter. One of the main limiting factors of the aircraft was with its wing encountering compressibility at high speed. The investigation led to interest in designing a laminar flow airfoil and adapting it to an existing Spitfire airframe. In late 1942, the British National Physics Laboratory joined the effort, and Supermarine issued Specification No 470 for the new Spitfire wing in November. As designed, the new wing was 200 lb (91 kg) lighter, would increase the aircraft’s roll rate, and was expected to increase the aircraft’s speed.

Supermarine Spiteful NN660 1st prototype

The first Supermarine Spiteful prototype (NN660) consisted of new laminar flow wings mounted to a Spitfire XIV fuselage. Note the wide and shallow radiator housings under the wings and the standard canopy

A proposal was submitted to the British Air Ministry and gathered enough interest for Specification F.1/43 to be issued in February 1943, calling for a single-seat fighter with a laminar flow wing for Air Force service and provisions for a folding wing to meet Fleet Air Arm (FAA) requirements. Supermarine proceeded with the design under the designation Type 371. Originally, the aircraft was to be named Victor or Valiant, names that were previously (but temporarily) applied to advanced Spitfire models. However, the Type 371 eventually had its name changed to Spiteful. Three prototypes were ordered, and a fourth was added later.

The design of the Supermarine Spiteful was overseen by Joseph Smith. The laminar flow wing was much thinner than the wing used on the Spitfire and necessitated a complete redesign. The all-metal wing had two spars and a straight taper on the leading and trailing edges, which simplified its manufacture. The skin used was relatively thick to add rigidity and improve aileron control. Unlike with the Spitfire, the landing gear retracted inward with the main wheels being housed in the comparatively thick wing roots. The landing gear struts compressed as the gear retracted to minimize the space needed within the wing. Wide and shallow radiators for engine cooling were housed behind the main gear wells. The oil cooler was positioned behind the coolant radiator in the left wing, and the intercooler radiator was positioned in front of the coolant radiator in the right wing. The radiator housings had adjustable inlets and exit flaps. Each wing had two 20 mm cannons with 167 rounds for each inner gun and 145 rounds for each outer gun. The underside of each wing could accommodate two 300 lb (136 kg) rockets or a hardpoint for a drop tank or a bomb up to 1,000 lb (454 kg).

The all-metal, monocoque fuselage of the Spiteful was similar to that of the Spitfire. The cockpit was raised to improve the pilot’s view over the aircraft’s nose. A new, sliding bubble canopy covered the cockpit. Four fuel tanks in the fuselage, forward of the cockpit, held a total of 120 gal (100 Imp gal / 455 L), and a tank in each wing root held 10 gal (8 Imp gal / 36 L). Starting with the third prototype, a 74 gal (62 Imp gal / 282 L) fuel tank was added behind the cockpit, bringing the total internal capacity to 214 gal (178 Imp gal / 809 L). Two 108 gal (90 Imp gal / 409 L) drop tanks could be carried under the wings, or a single 204 gal (170 Imp gal / 773 L) drop tank could be mounted to the aircraft’s centerline.

Supermarine Spiteful NN664 2nd prototype

The Spiteful prototype (NN664) is considered the first true Spiteful because it incorporated the new fuselage. The aircraft was never painted. Note the standard, Spitfire F.21 tail.

The Spiteful’s Mark numbers were a continuation of those used on the Spitfire. The Spiteful F.XIV (F.14) was powered by a 2,375 hp (1,771 kW) Rolls-Royce Griffon 69 with a five-blade, single-rotation propeller. The Spiteful F.XV (F.15) was powered by the 2,350 hp (1,752 kW) Griffon 89 or 90 with a six-blade, contra-rotating propeller. Both Griffon engines had a two-stage, two-speed supercharger, and both the five- and six-blade propellers were 11 ft (3.35 m) in diameter and built by Rotol. Originally, a Rolls-Royce Merlin engine could be substituted for the Griffon if Griffon engine production was found to be lacking, but the Merlin option was dropped in mid-1944.

The Spiteful had a 35 ft (10.67 m) wingspan, was 32 ft 11 in (9.76 m) long, and was 13 ft 5 in (4.10 m) tall. The aircraft had a maximum speed of 409 mph (658 km/h) at sea level, 437 mph (703 km/h) at 5,500 ft (1,676 m), and 483 mph (777 km/h) at 21,000 ft (6,401 m). Cruising speed for maximum range was 250 mph (402 km/h) at 20,000 ft (6,096 m). The Spiteful’s stalling speed was 95 mph (153 km/h). The aircraft’s range was 564 mi (908 km) on internal fuel and 1,315 mi (2,116 km) with drop tanks. The Spiteful had an empty weight of 7,350 lb (3,334 kg), a normal weight of 9,950 lb (4,513 kg), and a maximum weight of 11,400 lb (5,171 kg). The aircraft had an initial rate of climb of 4,890 fpm (24.8 m/s) and a ceiling of 42,000 ft (12,802 m).

Supermarine Spiteful NN667 and RB523 long scoop

A comparison of the third Spiteful prototype (NN667) and the ninth F.XIV production aircraft (RB523). Both have the elongated intake scoop mounted under the engine and just behind the spinner. Note the larger tail compared to the first two Spiteful prototypes.

With other war work taking priority, it was some time before Supermarine had anything related to the Spiteful to test. A mockup was inspected in March 1944, and the aircraft’s name was changed to Spiteful around this time. A set of wings was fitted to a Spitfire XIV (serial number NN660), which became the first Spiteful prototype. The aircraft was first flown on 30 June 1944, with Jeffrey Quill as the pilot. The aircraft used the same 2,035 hp (1,518 kW) Griffon 61 engine as installed in a standard Spitfire XIV, but its performance was superior to that of a standard Spitfire XIV. However, the Spiteful also exhibited rather violent stalling characteristics compared to the fairly docile stall of the Spitfire. This was attributed to the outer wing with the aileron stalling first, which was the opposite of how the Spitfire’s elliptical wing stalled. With the Spitfire, the outer wing stalled last and enabled the ailerons to remain effective deep into the stall. On 13 September 1944, NN660 crashed while engaged in a dog-fight test with a standard Spitfire XIV. The pilot, Frank Furlong, was killed in the crash. A definitive cause was never determined, but it was believed that the aileron control rods became jammed during moderate G maneuvers.

On 8 January 1945, the second Spiteful prototype (NN664) took to the air, piloted by Quill. The aircraft incorporated updated aileron controls and the new Spiteful fuselage. However, NN664 had a tail similar to that used on the Spitfire F.21. Extensive handling tests were undertaken on NN664 that resulted in a few changes. The most significant change was a redesigned tail with its vertical stabilizer and rudder area increased by 28 percent and its horizontal stabilizer and elevator area increased by 27 percent. NN664 first flew with the new tail on 24 June 1945, and the aircraft was sent to the Aeroplane and Armament Experimental Establishment (A&AEE) at RAF Boscombe Down for flight trials.

Supermarine Spiteful RB515 underside

The underside of Spiteful RB515, the first production aircraft, illustrates the wings’ straight leading and trailing edges. Note the standard, short intake scoop. Outlines of the radiator housing doors are visible.

Shortly after NN664’s first flight, the Air Ministry ordered 650 Spiteful aircraft. The order went through a number of reductions, including the cancellation of 150 Spitefuls around 5 May 1945 so that a comparable number of Seafangs (see below) could be ordered. The fourth prototype was included in these cancellations.

The third Spiteful prototype (NN667) was sent to the A&AEE for service evaluations on 1 February 1946. It was found that the aircraft exhibited several areas of poor build quality, and there were numerous concerns with its ease of serviceability. A multitude of fasteners needed to be undone in order to remove the engine cowling, and rearming the aircraft was a time-consuming process that involved disconnecting the controls to the ailerons. A number of modifications and improvements were suggested, but it is not clear just how many were implemented. For at least part of its existence, NN667 had an elongated air intake that would be featured on the Seafang (see below). Other Spitefuls also had the longer scoop (at least RB517, RB518, RB522 and RB523).

The first production Spiteful F.XIV (RB515) made its first flight on 2 April 1945, with Quill in the pilot’s seat. The aircraft originally had an F.21 tail, but a larger Spiteful tail was installed after RB515’s third flight, which ended in a forced landing. The aircraft’s first flight with the new tail was on 21 May 1945. On 27 September 1945, RB515 suffered an engine failure and made another forced landing at Farnborough. The damaged aircraft was subsequently written off.

Supermarine Spiteful RB515 in flight

Another view of RB515 illustrates the larger Spiteful tail that was later applied to the Spitfire F.22 and F.24. The tail improved the Spiteful’s handling, but the aircraft’s stall was still violent compared to the Spitfire’s.

Spiteful RB518 was fitted with a rounded Seafang (see below) windscreen and a 2,420 hp (1,805 kW) Griffon 101 engine to become the sole Spiteful F.XVI (F.16). The Griffon 101 had a two-stage, three-speed supercharger and turned a five-blade, single rotation propeller. In 1947, RB518 achieved 494 mph (795 km/h) at 27,800 ft (8,473 m), the highest level-flight speed recorded by a British piston-powered aircraft. Testing of this aircraft with not-fully-developed engines resulted in seven forced landings—the last was at Chilbolton in March 1949 and resulted in the landing gear being pushed through the wings. The aircraft was then dropped by the recovery crane, ending any hope of repair.

By February 1946, the Spiteful order had been reduced to 80 aircraft. This was again reduced on 22 May 1946 to 22 aircraft, and the Spiteful order finally dropped to 16 aircraft on 16 December 1946. The production order basically covered the aircraft that had been built, although some of the last aircraft may not have flown. A 17th Spiteful, RB520 (the sixth production aircraft), was handed over to the FAA for Seafang (see below) development on 22 September 1945. The aircraft was modified for carrier feasibility trials with a “stinger” arrestor hook incorporated into a special housing below the rudder. RB520 retained the standard, non-folding Spiteful wings.

Supermarine Spiteful RB518

Powered with a two-stage, three-speed Griffon 101 engine, Spiteful RB518 achieved a level-flight speed of 494 mph (795 km/h), the highest recorded by a British piston-powered aircraft. RB518 was the only F.XVI Spiteful and was subsequently written off after its seventh forced landing.

The production aircraft were serialed RB515 to RB525, RB527 to RB531, and RB535. The final Spiteful was delivered on 17 January 1947. Of the three Spiteful prototypes and 17 production aircraft, most were sold for scrap in July 1948. It appears RB518 was the last Spiteful to fly, and no examples of the type survive. The larger “Spiteful tail” was incorporated into the last Spitfires, the F.22 and F.24.

The Spiteful’s cancellation was based on a number of realities including the more impressive performance of jet aircraft, the end of World War II, and serviceability questions about the Spiteful. While the Spiteful’s speed was impressive, it was below the 504 mph (811 km/h) that was originally estimated. Furthermore, the performance of the aircraft’s laminar wing decreased substantially if there were imperfections, including smashed bugs, on the leading edge. It was unlikely that an in-service warplane would be free of all imperfections.

Supermarine Spiteful RB520

Spiteful RB520 was loaned out for Seafang development and is considered by some as a Seafang prototype. Note the tail hook housed below the rudder and the “Royal Navy” stenciling on the fuselage.

Back in October 1943, Supermarine designed the Type 382, which was basically a navalized Spiteful. The design had started with mounting a Spiteful-type, laminar flow wing on a Seafire XV. Little official interest was given to the project until 21 April 1945, when the Air Ministry issued Specification N.5/45 for a single-seat fighter for the FAA. Subsequently, Supermarine was awarded a contract for two prototype Type 382 fighters, which became the Seafang. An order for 150 Seafang aircraft was placed on 7 May 1945; this order was essentially a reallocation of Spiteful aircraft that had been cancelled around two days prior.

The production Seafang closely matched the Spiteful but incorporated wings designed so that the last four feet folded vertically. The folding mechanism was hydraulically-powered. The Seafang had an elongated carburetor intake scoop, with the opening just behind the propeller. The aircraft also had a rounded front windscreen rather than the flat plate used on the Spiteful. Under the rudder was a stinger tail hook for catching the arresting cables on the carrier deck. The Seafang’s landing gear was re-enforced to handle carrier operations. The fuel tank behind the cockpit was reduced to 54 gal (45 imp gal / 205 L), resulting in a total internal capacity of 193 gal (161 Imp gal / 732 L).

Supermarine Seafang VG471 front

The first production Supermarine Seafang F.31 (VG471) was essentially a Spiteful with arrestor gear. All F.31 aircraft had standard, non-folding wings. Note what appears to be a wide-cord propeller.

Like the Spiteful, two Seafang variants were planned. The F.31 used the 2,375 hp (1,771 kW) Griffon 69 engine with a five-blade, single-rotation propeller, while the F.32 used the 2,350 hp (1,752 kW) Griffon 89 with a six-blade, contra-rotating propeller. The F.31 was basically a Spiteful with an arrestor hook and did not incorporate folding wings. The F.31s would serve as a test aircraft while the F.32 was being developed.

The Supermarine Seafang had a 35 ft (10.67 m) wingspan, was 34 ft 1 in (10.39 m) long, and was 12 ft 7 in (3.84 m) tall. With wings folded, the span was reduced to 27 ft (8.23 m). The aircraft had a maximum speed of 397 mph (639 km/h) at sea level, 428 mph (689 km/h) at 5,500 ft (1,676 m), and 475 mph (764 km/h) at 21,000 ft (6,401 m). Cruising speed for maximum range was 250 mph (402 km/h) at 20,000 ft (6,096 m). The aircraft’s range was 393 mi (632 km) on internal fuel. The Seafang weighed 8,000 lb (3,629 kg) empty, 10,450 lb (4,740 kg) with a normal load, and 11,900 lb (53,98 kg) maximum. The aircraft had an initial rate of climb of 4,630 fpm (23.5 m/s) and a ceiling of 42,000 ft (12,802 m).

Supermarine Seafang VG471

The side view of Seafang VG471 illustrates many of the aircraft’s features: long intake scoop, straight wing edges, radiator scoop doors, rounded windscreen, bubble canopy, large tail, and arrestor hook.

As previously mentioned, some Spitefuls had the long intake carburetor scoop; RB518 had a Seafang windscreen; and RB520 was fitted with an arrestor hook (resulting in some sources classifying it as a Seafang prototype). This was all done to lead up to Seafang F.31 production aircraft, which were basically Spitefuls with arrestor hooks. The first Seafang F.31 was VG471, which followed the fifth Spiteful off the production line. All of the F.31s had the five-blade propeller, lacked folding wings, and would end up the only production Seafangs that were completed. VG471 was first flown in early January 1946 and used in arrestor hook trials. The original hook installation proved to be weak, and a redesigned system was installed in March 1946. The aircraft passed the trials on 1 May.

The prototype Seafang F.32s were serial numbers VB893 and VB895, and both had contra-rotating propellers and folding wings. VB895 was first flown in early 1946 and was delivered to the A&AEE on 30 June. In August 1946, VB895 was demonstrated separately to the Royal Netherlands Navy, French representatives, and United States representatives in an attempt to sell the Seafang to allies. However, no orders were placed. In May 1947, test pilot Mike Lithgow successfully performed deck trials in VB895 on the HMS Illustrious. The aircraft’s wide track landing gear drastically increased its stability while on the ground, and the contra-rotating propeller eliminated the torque effect. VB895 was also tested with a single, fuselage-mounted 204 gal (170 Imp gal / 773 L) drop tank, and the aircraft was used for armament trials. During a static test firing of the cannons on 18 May 1948, a build-up of gases in the left wing resulted in an explosion that damaged the wing. Extra vents were added, and no further issues occurred.

Supermarine Seafang VB895

The Seafang F.32 prototype VB895 was the first fully-navalized aircraft of the series. The contra-rotating propellers eliminated the torque effect that led to the downfall of many aviators, especially when operating from the short deck of an aircraft carrier.

While praised for its handling and responsiveness, the Seafang did not offer any real advantage over the Seafire 47, and the Seafang’s stall was certainly a disadvantage. An order was subsequently placed for the Seafire. The original interest in the Seafang was based on doubts regarding the suitability of jet aircraft for carrier operations. As those doubts faded, so did interest in the Seafang, and the aircraft was cancelled. A few Seafangs were kept active for a brief time to continue evaluating the laminar flow wing, which was used on the Supermarine Type 392 Attacker. The Attacker was often referred to as a “Jet Spiteful,” although it had Seafang folding wings with the radiators removed and additional fuel tanks installed. The Attacker first flew on 27 July 1946, and it was the first jet fighter to enter operational service with the FAA.

Eighteen production Seafangs were built, carrying serial numbers VG471 to VG490. The first 10 aircraft were F.31s, and the remaining eight were F.32s. However, only the first eight or so aircraft were completed, with the remaining units delivered disassembled. Sadly, like the Spiteful, all of the Seafang examples were scrapped.

Note: The Royal Air Force and Fleet Air Arm used Roman numerals for mark numbers up thorough 1942. From 1943 through 1948, the Roman numerals were phased out for new aircraft, and Arabic numerals were applied. From 1948 onward, Arabic numerals were used exclusively. The Spitefuls were typically referred to using Roman numerals, but the slightly later Seafang used Arabic numerals. The use of both Roman and Arabic numerals in this article refers to the most common use applied for the particular aircraft type.

Supermarine Seafang VB895 wings folded

The folding wings on Seafang VB895 were hydraulically operated and decreased the aircraft’s wingspan by 8 ft (2.4 m). Although, the wide tack landing gear contributed to snaking at low speeds, it enhanced the stability at higher speeds and as the aircraft slammed down on a carrier deck.

Sources:
Spitfire: The History by Eric B. Morgan and Edward Shacklady (2000)
British Experimental Combat Aircraft of World War II by Tony Buttler (2012)
Supermarine Aircraft since 1914 by C.F. Andrews and E.B. Morgan (1981)
Ultimate Spitfires by Peter Caygill (2006)
Supermarine Fighter Aircraft by Victor F. Bingham (2004)
Griffon-Powered Spitfires by Kev Darling (2001)
Fighters: Volume Two by William Green (1961)
Interceptor Fighters for the Royal Air Force 1935–45 by Michael J.F. Bowyer (1984)
Spitfire: A Complete Fighting History by Alfred Price (1992)
Wings of the Weird & Wonderful by Captain Eric Brown (2012)