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14.4. Final conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
Further reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266
1. Introduction be introduced, e.g. Reeves defines the GE as a
phenomenon of aerodynamic, aeroelastic and aero-
This survey is dedicated to the memory of a acoustic impacts on platforms flying in close proxi-
distinguished Russian engineer Rostislav E. Alex- mity to an underlying surface [2]. The term ‘‘extreme
eyev who was the first in the world to develop the ground effect (EGE)’’ implies a range of relative
largest ground-effect (GE) machine—Ekranoplan. ground clearances of 10% of the chord of the main
His first creation, the top secret project KM became wing or less [3].
known to the western world as the Caspian Sea A wing-in-ground (WIG) effect vehicle can be
Monster because of hovering movements of this defined as a heavier than air vehicle with an engine,
mammoth craft over the Caspian Sea. The KM which is designed to operate in proximity to an
became the prototype for many other advanced underlying surface for efficient utilization of the GE.
marine vehicles utilizing favorable influence of the
underlying surface upon aerodynamics and eco- 1.2. Different names of WIG effect craft
nomics, Fig. 1.
The story of the Caspian Sea Monster has At present many terms exist to designate such a
acquired a publicity, which far surpassed that of craft. The names ekranoplan (from the French word
the Loch Ness Monster. These two tales may appear ´
ekran ¼ screen), nizkolet (low flying vehicle), ekrano-
similar to an uninformed reader. In fact, loch means let (vehicle able to fly in and out of GE) originated
a lake in Gaelic, and the Caspian Sea is often viewed from Russia (R. Alexeev) [4]. WIG is a popular
as an enormous lake. Both monsters were huge and abbreviation of WIG effect vehicle. WISES (intro-
tended to avoid the human eye. Actually, only a few duced by S. Kubo, Japan) spells as Wing-In-Surface
lucky ones saw them ‘‘in flesh’’, and both had to be Effect Ship. GEM (Bertelson, USA) stands for GE
identified from photos. Machine. The terms Flaircraft, Tandem-Aerofoil Boat
With the end of the Cold War, the mystery of the were introduced by Gunther Jorg (Germany). The
¨ ¨
Caspian Sea Monster exists no more. But the Lippisch craft derivatives developed by Hanno
breathtaking technology behind the development Fischer (Germany) are called Airfish. The technology
of large flying ships taking advantage of the surface of air-cushion-assisted takeoff, applied by Fischer,
effect at aviation speeds may revolutionize the got an imprint in the term Hoverwing. The vehicles of
future fast sea transportation. Techno Trans (Germany) are known as Hydrow-
ing(s). S. Hooker (Aerocon, USA) coined the term
1.1. Definitions of the ground effect and wing-in- Wingship designating WIG vehicles of mammoth size
ground effect vehicles [5] As per Hooker, this term ‘‘designates very
specifically a ship-sized winged craft that ordinarily
In what follows ‘‘the ground effect (GE)’’ is takes off from and lands in water and which flies at
understood as an increase of the lift-to-drag ratio of high speed’’. The term RAM Wing applies to the
a lifting system at small relative distances from an WIG vehicles for which the main contribution to the
underlying surface [1]. More general definitions may lift is due to stagnated flow under the main wing. A
WIG vehicle permanently using power augmentation
to enhance the dynamic lift is sometimes called
PARWIG.
1.3. Distinctions from existing airborne and
waterborne vehicles
The WIG effect vehicle differs from a conventional
Fig. 1. The KM dubbed ‘‘The Caspian Sea Monster’’. airplane by the relatively small aspect ratio of the
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214 K.V. Rozhdestvensky / Progress in Aerospace Sciences 42 (2006) 211–283
a ‘‘pancake’’ landing. The transatlantic service of the
seaplane Dornier DO-X demonstrated augmentation
of the payload and range (1930–1931). Improved ride
and handling qualities of conventional military
aircraft (F105D, B-58, Avro Vulkan) even at
distances exceeding five span lengths above the
ground were regularly experienced, see [5].
The first purposefully designed GE vehicle was
due to Kaario (Finland, 1935) [7]. His ‘‘Aerosledge
Fig. 2. WIG versus airplane (KM versus AN-225 ‘‘Mria’’). No. 8’’ featured a small-aspect ratio wing, leaning
upon the skis (skegs) and a swiveling wing, directing
the air propeller jet under the main wing. To
main wing, endplates (floats), special takeoff and provide additional static stability margin Kaario
alighting gear (takeoff or liftoff aids). The distinc- added two longitudinal rear beams with small
tion from a conventional airplane can be seen from stabilizing surfaces [4], Fig. 3.
Fig. 2, comparing the KM ekranoplan with the A precursor of the power augmentation system
AN-225 (‘‘Mria’’) aircraft of similar size and weight. can be found in the Warner ‘‘compressor’’ airplane
The Soviet Military encyclopedia adds to this list (USA, 1928) [4], Fig. 4. The design was based on a
of distinctions of the ekranoplan the ‘‘raised canard configuration and included two powerful
location of the horizontal tail unit, beyond the fans forcing the air under a dome-like bottom of the
limits of the influence of the ground and the wing vehicle. The Warner was the first to use separate
wake, to ensure longitudinal stability’’ [6]. Note that takeoff and cruise engines.
the latter feature may degenerate or completely The ram-wing concept was implemented by
vanish from some configurations such as ‘‘tandem’’, Troeng (Sweden, 30s) [4], Fig. 5. Particular features
‘‘flying wing’’ or ‘‘composite wing’’. Contrary to the of Troeng’s rectangular-wing vehicles were: (1)
aircraft the WIG vehicles do not have to be enhanced static stability during takeoff with the
hermetic. Conventional seaplanes versus WIGs help of special floats, (2) use of a screw propeller, (3)
have: much larger aspect ratio and higher position- use of a small hydrofoil at the trailing edge of the
ing of the main wing with respect to the hull, i.e. are ram wing to ensure longitudinal stability in the
less subject to the action of GE. Seaplanes (except design cruising mode.
Bartini’s VVA-14) are of airplane aerodynamic
configuration. As compared to the hovercraft which
is borne by a static air cushion, the WIG is
supported by a dynamic air cushion that forms
under the lifting wings at large speeds (RAM or
chord-dominated GE) or/and by the wing-generated
lift enhanced due to reduction of the down wash
near the ground (span-dominated GE). While
sharing some features with high-powered planing
boats, the WIG is supported by dynamic pressure of
the air whereas the planing boat is supported by the Fig. 3. Kaario’s Aerosledge No. 8.
dynamic pressure of the water.
2. A brief history of WIG effect vehicles
2.1. First inventions and applications based on the
GE technology
The earliest practical albeit unintentional utiliza-
tion of GE belongs to the Wright brothers. The
aviators encountered GE phenomena under the
disguise of what was called a ‘‘cushioning effect’’ or Fig. 4. Warner’s ‘‘Compressor’’ airplane.
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K.V. Rozhdestvensky / Progress in Aerospace Sciences 42 (2006) 211–283 215
was provided for takeoff and landing with engines
cantilevered from the sides of the forward fuselage.
The twin vertical and all-movable horizontal
empennage is supported from the wing trailing edge
by twin tail booms. A single, V-shaped hydrofoil
was incorporated into the Lockheed wingship
design for landing purposes only. The foil had a
Fig. 5. Troeng’s ram wing. span of only 15.2 ft (4.64 m) and a chord of 7.6 ft
(2.3 m). The hydrofoil is extended at 150 ft/s (89
knots, i.e. about 165 km/h). Darpa report also
describes Northrop Wingship 1.6 M and Douglas
Aircraft Wingship-S. The former vehicle has the
following main characteristics: TOW ¼ 1.6 mln lb
(725 tons), length of 282 ft (86 m), wing span
of 141.4 ft (43 m), aspect ratio 2.6, wing loading
206 lb/sq. ft (about 1000 kg/sq m). Structural and
empty weight fractions of the vehicle were 32% and
47% correspondingly.
The 2 million lb (910 tons) Douglas Aircraft
Fig. 6. Ground-effect machine designed by Bertelson. Wingship-S (1977) was supposed to use the power
augmented ram (PAR) wing concept. The underw-
ing cavity pressure was provided from the exhaust
2.2. Projects and vehicles worldwide of the four canard-mounted engines. In the DAW-S
the PAR was used at all speeds and the forward
Further extension of Kaario’s idea to combine engines were fixed at a certain angle. The underwing
features of WIG effect and air-cushion vehicles was pressure is sustained by plain flaps at the rear of the
implemented in Bertelson’s (USA, late 50s–early 60s) wing and a pressurized inflatable skirt extending
GEMs [4], Fig. 6. Similar to Kaario’s design, the vertically along the wing tips. As per the DARPA
GEMs had a single engine for takeoff and cruise. report, the DAW-S takes off and lands vertically
They took off and cruised by means of an air cushion at zero forward speed, thus experiencing no
generated by deflecting the propeller air stream under hydrodynamic forces due to forward motion. The
off the main wing. Stabilization of the vehicle was wing is mounted flush with the bottom of the
provided by a number of control surfaces: small fuselage to prevent wave impact. The fuselage,
forward flaps, mounted right after the propeller, and therefore, is similar to the conventional land plane
high-mounted albeit small tail plane. design and has no seaplane keel, chines or deadrise
Lockheed had been involved in WIG craft contours and is designed for floating loads only. A
development since 1960. In 1963 a small two-seat substantial ski structure is included under the aft
boat with a wing fitted with endplates was launched fuselage to assist in the vehicle longitudinal trim
(Koryagin). It had two bow hydroskis for better during takeoff and landing. A conventional T-tail
longitudinal stability [4]. A similar cutter ‘‘Clipper’’ empennage also maintains trim and stability at
was built in 1965. Beside cutters, Lockheed is forward speeds. Quite a unique craft was developed
known to have studied a large WIG effect flying in the 60s by the Swiss engineer Weiland within his
catamaran. The vehicle was to be stabilized and contract with the US company ‘‘West Coast’’ [4].
controlled by flap ailerons and a tail unit, compris- Weiland vehicles comprise a twin-hull structure with
ing of vertical and horizontal rudders. The cargo two large wings of aspect ratio 5 configured in a
was to be transported in the hulls and the wing. tandem. The ‘‘Small Weilandcraft’’ of 4.3 tons was
Later, Lockheed-Georgia (see DARPA Report to be followed by a 1000—ton ‘‘Large Weiland-
[8]) studied a 1362 million lb (620 tons) wingship, craft’’ with length in excess of 200 m and width of
which was designed as a logistics transport capable more than 150 m, Fig. 7. Sufficient attention was
of transporting about 200 tons over 4000 nautical attached to providing efficient takeoff.
miles (7410 km) over an open ocean in a sea state 3 As an alternative to hydroskis, Weiland proposed
environment at a cruise speed of 0.40 Mach. PAR power augmentation. He also introduced special
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216 K.V. Rozhdestvensky / Progress in Aerospace Sciences 42 (2006) 211–283
Fig. 7. Weiland’s ‘‘Large Weilandcraft’’ Project. Fig. 9. Lippisch X-114.
Fig. 10. Kawasaki KAG-3 craft (S. Ando).
Fig. 8. TAF VIII-1 tandem vehicle (Gunther Jorg).
¨ ¨
when landing on the water surface, hydrofoils were
mounted on the vehicle, two in the front and one at
inflatable shells on the bottoms of the hulls to the stern. Beside these small craft Lippisch also
reduce the impact of waves during takeoff. The studied the design of much larger machines.
‘‘Small Weilandcraft’’ crashed during the tests One such design was that of a 300-ton GE
supposedly due to lack of static stability. Beginning machine with a 6-engine power plant of 50,000 hp,
from 1963 Gunther Jorg in Germany designed and
¨ ¨ able to carry 300 passengers at a cruising speed of
built a series of ground-effect vehicles (TAF ¼ 300 km/h [4].
Tandem-Airfoil-Flairboat) based on the idea of Three types of WIG effect vehicles were developed
arranging two stubby wings in tandem [9], Fig. 8. by the Japanese company Kawasaki (KAG-1, KAG-2
He was able to ensure static stability and controll- and KAG-3) [4,10]. The vehicles were designed by
ability of the vehicle in longitudinal motion by a Ando. The KAG-3 vehicle (takeoff weight of 0.7 ton,
proper ‘‘tuning’’ of parameters of the forward and length 5.9 m, width with stabilizers about 6.15 m,
rear wings and their design pitch angles. Thereby screw propeller) was built and tested in 1963, Fig. 10.
the longitudinal steering control is reduced to
throttle control only. 2.3. Russian ekranoplans
Lippisch—a German aerodynamicist, who
worked for the US company Collins Radio— The Russian developments started in the early
introduced new WIG effect vehicles based on the sixties almost simultaneously in the Taganrog
reverse delta wing planform. In 1963 he built his Aviation Construction Complex headed by Beriev
first X-112 ‘‘Aerofoil Boat’’. This and the following and in the Central Hydrofoil Design Bureau
Lippisch craft had a moderate aspect ratio in excess (CHDB) in Nizhniy Novgorod [11–13].
of 3 and inverse dihedral of the main wing enabling The vehicles developed in Taganrog under the
them to elevate the hull with respect to the water guidance of Bartini were seaplanes rather than
surface. The reported lift-to-drag ratios were of the ekranoplans in the direct sense of the word. The
order of 25. Besides, a forward-swept delta wing in idea behind Bartini’s designs was to provide
combination with a relatively large high-mounted contact-free takeoff and landing of a seaplane using
tail plane appear to provide sufficient longitudinal the GE.
stability in a range of flight heights including Two anti-submarine airplanes named Vertical-
cruising close to the ground and dynamic jump takeoff-Amphibia were built possessing improved
modes. seaworthiness and being able to takeoff and land at
In the 70s the series was extended to the X-114 practically any sea state. The development started
(takeoff weight of 1.35 tons) which was commis- with the small single-seat seaplane Be-1 built in
sioned by the German Ministry of Defense, Fig. 9. 1961. It had a low-aspect-ratio main wing between
In order to reduce significant loads encountered two floats (hulls) and small side wings. The vehicle
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K.V. Rozhdestvensky / Progress in Aerospace Sciences 42 (2006) 211–283 217
dihedral which appeared later on SM-8 and the KM
itself. Eight marinized turbofan engines of 10-ton
maximum thrust each were mounted on the front
pylon forward of the main wing to provide PAR
Fig. 11. Vertical-takeoff Amphibia (Bartini, Beriev Bureau). takeoff. Another two identical engines were in-
stalled at about mid-height of the vertical stabilizer
was propelled by a turbojet engine mounted on the and were used for cruising. After extensive tests in
upper side of the main wing. To facilitate liftoff 1967–69, KM showed: efficient takeoff in waves up
surface-piercing hydrofoils were fitted on the floats. to 3 m, smooth flight, amphibious capability (ability
Next was VVA-14 which had a length of 26 m, of going onto a shallow water area and a beach),
width of 6 m, takeoff weight of 52 tons and cruising and good longitudinal stability in the whole range of
speed of 760 km/h at altitude of 10 km, Fig. 11. design heights.
This was essentially a flying catamaran. Its basic The next vehicle of the KM family was ‘‘Orlyo-
part was a small-aspect-ratio center-wing of rectan- nok’’ (1973, with 120-ton takeoff weight, length of
gular planform bounded by two hulls. The fuselage 60 m, aspect ratio 3 main wing), Fig. 12.
was mounted toward the front part of the wing Differently from KM, ‘‘Orlyonok’’ had two PAR
along its axis and two side wings were fitted behind engines of 10-ton static thrust ‘‘hidden’’ in the bow
the center of gravity (CG). The liftoff was to be part of the fuselage. Cruise propulsion was provided
provided by 12 engines on the center wing. In fact by a 16-ton static thrust turboprop engine, mounted
these were power augmentation engines. Two D- at the intersection of the vertical stabilizer and the
30 M turbofan cruise engines were located rear- tail plane, and two counter-rotating variable pitch
wards above the central wing so that they were propellers with diameter in excess of 6 m. The
protected against water ingestion. Also there were turboprop engine not only ensured higher efficiency
14-m long inflatable pontoons fitted on the bottom than the jet, but also the variable pitch propellers
of the side hulls. provided remarkable low-speed maneuverability in
However, the main developments of what is now the PAR mode.
called ekranoplan were made in CHDB by Alex- In 1987, the next representative of the KM family
eev’s team which viewed the vehicle’s flight close to was launched—a missile carrier ‘‘Loon’’ (400-ton
the underlying surface as the main regime of takeoff weight, 450 km/h cruising speed, length of
operation. The first piloted ekranoplan SM-1 of 3- 74 m, main wing aspect ratio exceeding 3). Its
ton takeoff weight was based on a tandem scheme peculiarity was that (due to the missile launching
(1960). This concept was later discarded because of mission) all eight engines (static thrust of 13 tons
the high speed of detachment from the water, each) were mounted on the bow pylon to serve both
‘‘stiffness’’ of flight and narrow range of pitch as PAR and cruise prime movers, Fig. 13.
angles and ground clearance for which this config- Another type of Russian WIG effect vehicles is
uration was longitudinally stable. known as Dynamic Air Cushion Ships or DACS
The 5-ton SM-2 prototype had a new configuration, [12,14]. The DACS concept was set forth by Alexeev
comprising a low-flying main wing and highmounted in the late 70 s with designs accommodating from 8
tail plane. Another revolutionizing novelty of this to 250 passengers. The basic element of DACS is a
vehicle was its capability to pressurize the air under wing of small aspect ratio bounded by skegs (floats)
the main wing by the exhaust of the engines located and rear flaps to form a chamber. The dynamic air
upstream in the front part of the vehicle. Thus
emerged a wing-tail configuration with PAR consti-
tuting the basis for the following series of ekranoplans
of the first generation.
As a result of a huge engineering effort involving
development and tests of many self-propelled models
there evolved a prototype KM with takeoff weight of
550 tons, length in excess of 90 m, cruise speeds
above 500 km/h, main wing of aspect ratio 2, Fig. 1.
The first small-scale KM prototype was the model
SM-5 although its tail plane did not feature a Fig. 12. Ekranoplan ‘‘Orlyonok’’ (Alexeev-Sokolov).
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218 K.V. Rozhdestvensky / Progress in Aerospace Sciences 42 (2006) 211–283
Research Center (CSSRC) in 1967 [15,16]. Since
then, during more than 30 years a total of nine small
manned test vehicles have been designed and tested
on lakes and in coastal waters (see table). The XTW
series was based on a wing-tail configuration with
the main wing having forward sweep as in Lippisch
Fig. 13. Ekranoplan ‘‘Loon’’ (Kirillovykh).
designs, Fig. 15.
In 1996 the CSSRC reported developing the
XTWII, XTW-III and XTW-IV WIG effect craft,
Fig. 15. A typical craft of this series is XTW-4 which
was slightly modified from XTW-2 to comply with
specific requirements from sea trials. This 20-
passenger WIG effect ship was first tested on the
Changjiang River in the autumn of 1999. The
vehicle comprises: a major hull (float), the main
Fig. 14. Dynamic air cushion boat ‘‘Volga-2’’.
wing supported by two minor floats, two vertical
stabilizers carrying a high-mounted tail plane. To a
certain extent the vehicle can be ascribed to wing-
cushion in the chamber under the wing is formed by tail configurations. The main wing features the
means of blowing of the air with special fans forward sweep, reminiscent of the Lippisch deltaw-
(propellers) mounted in front of the vehicle. The ing concept. Two P&WC PT6A-15AG turboprop
overpressure under the wing equals or exceeds the engines with MT’s 5-bladed adjustable pitch pro-
weight of the vehicle even at zero or small speed. As pellers are mounted at the leading edge of the main
the speed increases, the augmentation of lift is wing. Thus, the slipstream is efficiently used to assist
additionally enhanced due to the dynamic head of takeoff. Also, the WIG effect sixseat vehicle SDJ 1
the oncoming air. For DACS the blowing (power using a catamaran configuration was developed [17].
augmentation) is a permanent feature present both In early eighties another Chinese organization,
in the cruising and takeoff–touchdown modes. MARIC, started developing what they called
Numerous tests carried out at the CHDB showed AWIG (Amphibious WIG) [18]. About 80 models
that efficiency of DACS is similar to that of were tested to study optimal wing profiles, config-
hydrofoil ships. At the same time, the speed of uration of the air channel, position of the bow
DACS far exceeds that of both the hydrofoil ships thrusters, arrangement of the tail wing, etc. A self-
and the ACVs. The first practical vehicle of DACS propelled radio-controlled model of 30 kg was
type was the Volga-2 cutter, Fig. 14. tested on Din-San lake in a suburb of Shanghai.
This 2.7-ton craft has a length of 11.6 m, width of As the model showed acceptable performance,
7.65 m and height of 3.6 m. The range of cruise MARIC proceeded to the development of the larger
speeds of Volga-2 is from 100 to 140 km/h. The craft AWIG-750 with a maximum TOW of 745 kg,
vehicle is propelled by the ducted air propellers length 8.47 m, span 4.8 m, height 2.43 m, Fig. 16.
mounted ahead of the wing. Inclination of their axes The power plant included internal combustion
and use of special hinged vanes serves to provide engines: two for lift and two for propulsion of the
both power augmentation and horizontal thrust. craft. Each engine drove a ducted thruster type DT-
The main lifting wing of the craft is almost square 30 of 30 hp rated power at 6000 rpm. The vehicle
and has S-shaped sections to enhance the long- was able to takeoff in waves of 0.5 m and had a
itudinal stability. As a result, the latter turns out to
be sufficient in spite of the relatively small tail area.
3. Recent projects
3.1. Projects and prototypes produced in China
Development and design of WIG effect craft in
China was started in the China Ship Scientific Fig. 15. XTW-1 vehicle (CSSRC, Wuxi, China).
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K.V. Rozhdestvensky / Progress in Aerospace Sciences 42 (2006) 211–283 219
In 1990 Fischer Flugmechanik tested a 4-seat
vehicle Airfish-3, which was 2.5 times heavier than
Airfish FF2, flew at a speed of 120 km/h and was
able to cover a range of 370 km [19], Fig. 17. With a
length of 9.45 m and a width of 7.93 m, the vehicle
had an operational clearance ranging from 0.1 to
Fig. 16. AWIG-751 (MARIC, China). 1 m. Although the craft was tailored for use in GE,
it could perform temporary dynamic jumps climbing
to a height of 4.5 m.
maximum speed of 130 km/h. It demonstrated the A design based on the Airfish series formerly
expected (amphibious) capability of passing from developed by Fischer Flugmechanik has re-emerged
the water to the shore and back. in Flightship 8 (FS-8 initially designated as Airfish 8)
In 1995, the China State Shipbuilding Corpora- [19], Fig. 18. The FS-8 was developed in Germany
tion commissioned the R&D for a 20-seat AWIG- by Airfoil Development GmbH and made its
751 under the name ‘‘Swan-I’’ to MARIC and the maiden flight in the Netherlands in February 2000.
Qiu-Sin Shipyard [18], Fig. 16. With its TOW of 2325 kg, length of 17.22 m, width of
The vehicle which was completed by June 1997 15.50 m and height of 4 m the Flightship-8 carries 8
had a TOW of 8.1 tons length–width–height people, including two crew. The wave height at
dimensions of 19 Â 13.4 Â 5.2 m3 and a maximum takeoff is restricted to 0.5 m, but when cruising the
cruising speed of 130 km/h in calm water. It had vehicle can negotiate 2-m waves. FS-8 is made of
three aviation-type piston engines: two HS6E FRP. With an installed power of 330 kW it has a
engines of 257 kW each for PAR lift and one cruising speed of about 160 km/h and a range of
HS6A engine of 210 kW for propulsion. The PAR 365 km. The customer is the Australian Company
engines drove two bow ducted 4-bladed air propel- Flightship Ground Effect Ltd. whose branch Flight-
lers and the cruise engines drove a two-blade ship Australia conducted trials of the vehicle in
variable pitch propeller. As compared to the Australia. The R&D and production work is
previous AWIG-750 it had several new features, monitored by Germanischer Lloyd with regard to
including: increased span of the main wing, classification of the craft.
composite wing, combined use of guide vanes and A larger Flightship-40 (FS-40) dubbed Dragon-
flaps to enhance longitudinal stability, CHIBA Clipper is being designed for up to 40 passengers in
composites to reduce structural weight. the commuter version for an equivalent payload of 5
The tests confirmed overall compliance with tons in alternative configurations. This larger craft
the design requirements, but showed some dis- has a length of 30 m, and the wingspan of 25 m can
advantages, namely, too long shaft drives of the be reduced to 20 m for onshore handling by folding
bow propellers, lower payload and lower ground winglets. The main construction material is alumi-
clearance than expected. The follow-on vehicle num, and the Pratt and Whitney turboprop-diesel
AWIG-751G (Swan-II) had increased dimensions,
a modified PAR engines layout and an improved
composite wing.
3.2. Projects and vehicles developed in Germany
Hanno Fischer, the former technical director of
Fig. 17. Airfish 3 (Hanno Fischer).
Rein-Flugzeugbau, set up his own company
Fischerflugmechanik and extended the Lippisch
design concept to develop and build a 2-seat
sports vehicle designated as Airfish FF1/FF2 [19],
Fig. 17.
Unlike X112 and the following X114, the Airfish
was designed to fly only in GE. It was manufactured
of GRP and reached a speed of 100 km/h at just half
the engine’s power during tests in 1988. Fig. 18. Airfish 8—Flightship 8 (Hanno Fischer).
10. ARTICLE IN PRESS
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engines developing 1000 kW will increase the cruis-
ing speed to about 225 km/h. Maximum takeoff
wave height is 1.2 m and increased wing span allows
over-water operation in 4 m seas. The originators
of the FS-8 design Fischer Flugmechanik and
AFD Aerofoil Development GmbH have recently Fig. 20. ‘‘Hydrowing’’ vehicle of Technotrans.
announced a proposal to produce a new craft
HW20 [20] combining WIG effect and static
air-cushion technology (see paragraph 9.2). The
design of HW20 (Hoverwing) employs a simple
system of retractable flexible skirts to retain an air
cushion between the catamaran sponsons of the
main hull configuration. This static air cushion is
used only during takeoff, thus enabling the vehicle
Fig. 21. Marine passenger Ekranoplan MPE-400 (D. Synitsin,
to accelerate with minimal power before making a
T&T—ATT—ATTK).
seamless transition to true GE mode, Fig. 19.
Techno Trans e.V. was established in 1993. The
company started its activities by performing quite parts: the one (central) taking advantage of the
extensive tests of Joerg tandem craft prior to power augmentation mode, and the one (side wings)
launching their own WIG effect craft, project adding efficiency and longitudinal stability in cruise.
Hydrowing [21] with the goal to build an 80- Provision of stability in this case has three major
passenger ferry. In the mid-nineties they built a 2- ingredients: special profiling of the central part of
seater prototype (Hydrowing VT 01) propelled by the main wing, horizontal tail (albeit relatively
two unducted propellers. The vehicle had a TOW of small), appropriate geometry and position of the
812 kg, length of 9.87 m and width of 7.77 m. With side wings. The designs, exploiting these features,
installed power of 90 kW it could sustain a cruising are those of the MPE (Marine Passenger Ekrano-
speed of 120 0 km/h and could operate in waves of plan) series (Designer General D. Synitsin), ranging
0.4 m. The main wing of the vehicle had S-shaped in TOW from 100 through 400 tons [14], Fig. 21.
cross-sections for better stability, and a high- The MPE-400 project (1993) has a TOW of 400
mounted horizontal stabilizer supported by two tons, length of 73 m, width of 53 m and height of
vertical fins at the stern [21]. 20 m. It is intended to carry 450 passengers. It
The present project of Techno Trans is designated features an overall aspect ratio of 4.5. For better
Hydrowing 06, Fig. 20. It has a TOW of 2.3 tons, stability the central wing sections were S-shaped
installed power of 210 kW, a length of about 14 m, a resulting in considerable reduction of the area of the
width of 11 m and a cruising speed of 125 km/h. It tail plane. The latter constitutes 27% of the area of
also adopts the forward sweep feature of the the main wing. For KM this factor was 50%.
Lippisch designs, has both air and water rudders, Because of the aforementioned specific features the
and is equipped with a small hydrofoil for takeoff ekranoplans of MPE type can be assigned to the
assistance. second generation.
3.3. New vehicles and projects in Russia 3.3.2. Amphistar-Aquaglide series
Ekranoplan Amphistar was developed and built
3.3.1. Marine Passenger Ekranoplans by the company ‘‘Technology and Transport’’
A composite wing configuration implies func- (Director and principal designer D. Synitsin) in
tional subdivision of the craft’s lifting area into two 1995 [22]. In 1997 this vehicle was awarded the
certificate of the Register of Shipping of the Russian
Federation as a cutter on dynamic air cushion. The
maximum TOW is 2720 kg, its L Â B Â H dimen-
sions are 10.44 Â 5.9 Â 3.35 m3. At cruising speed of
150 km/h it has a range of up to 450 km. Seaworthi-
ness is about 0.5 m. The turn radius at cruising
Fig. 19. Hoverwing-20 with a static air-cushion liftoff system. speed is about 65 hull lengths. In water the turn
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K.V. Rozhdestvensky / Progress in Aerospace Sciences 42 (2006) 211–283 221
Fig. 22. Aquaglide-5 wing-in-ground effect vehicle (Synitsin,
ATT-ATTK).
Fig. 24. (a) Transport Amphibious Platform (project, CHDB).
(b) Transport Amphibious Platform Aquaglide-60 (project, ATT-
ATTK).
Fig. 23. Aquaglide-50 (project, Synitsin, ATT-ATTK). and a bow cockpit. The propulsion engines are
mounted on the tail plane. The claimed advantages
of the TAPs are high-speed (up to 250 km/h),
radius is about a hull’s length. A modified version of amphibious capacity, ability to carry superheavy
the vehicle has recently appeared under the name and oversized cargoes, high weight efficiency (up to
Aquaglide, Fig. 22. Synitsin developed a scaled 40–50%) due to a structural scheme simplified
up series of Amphistar-Aquaglide-type vehicles, versus hovercraft and WIG craft, low specific load
Fig. 23. Another example of larger dynamic on the supporting surface of the skegs (close to that
air-cushion vehicles scaled up from the Volga-2 of a skier on a snow surface), making the vehicle
cutter is a 90-passenger high-speed river craft ecologically friendly.
Raketa-2 designed to cruise at a speed of 180 km/h The TAPs [23] are claimed to have advantages
for ranges up to 800 km, and powered by a gas compared to hovercraft: 2 times larger speed; high
turbine. CHDB has also developed a conceptual seagoing qualities providing stable motion in rough
design of a 250–300 passenger dynamic air-cushion seas without flexible skirts; high cargo-carrying
ship Vikhr-2. capacity and weight efficiency; relatively simple
structure featuring no complicated multi-element
3.3.3. Transport Amphibious Platforms (TAP) power plant with reduction gears, transmissions
This new concept of fast water amphibious and hover fans. The TAP aerodynamic efficiency
transport developed by the CHDB and ATT-ATTK (lift-todrag ratio) is 10–12 at a speed of the order of
has speeds in the range of those of a hovercraft and 135 knots.
WIG effect craft, Figs. 24a and b. Like the Dynamic
Air Cushion Craft the TAP are supported both by 3.4. Projects and vehicles in the USA
the dynamic head of the oncoming flow and by that
of the jet exhaust of the bow PAR engines. At the In the early 90s, a US company named AERO-
same time, the TAP moves in constant contact with CON developed a project Aerocon Dash 1.6 [8],
the water surface (note that the ATT-ATTK Fig. 25. This mammoth Wingship had the following
concept of TAPs admits gaps between the vehicle physical characteristics: TOW ¼ 5000 tons, payload
and water surface). High efficiency is achieved fraction of 0.3588, wing loading of 258 lb/sq. ft
through a proper combined use of the aerodynamic (1260 kg/sq m), cruise speed of 400 knots (740 km/h),
GE and high hydrodynamic quality of the elongated cruise altitude of 12 ft (3.66 m). As underlined in
planing hulls (floats). The main structural compo- the DARPA report, a unique characteristic of the
nent of the TAP is a cargo platform with long- Dash 1.6 is its land overflight capability. A flight
itudinal side skegs, the bow pylon with PAR engines altitude of 6000 ft (1830 m) and a speed of 400 knots
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222 K.V. Rozhdestvensky / Progress in Aerospace Sciences 42 (2006) 211–283
Fig. 26. Lockheed Martin SEA (surface-effect-aircraft) concept.
Fig. 25. Aerocon Dash 1.6 ‘‘Wingship’’ (Stephan Hooker).
400 knots and a global range with 400 tons of
were assumed for the transit over land barriers. payload.
Whereas in free flight lift-to-drag ratio was esti- As reported by Boeing Frontiers (online, Septem-
mated as 15, in design GE mode the expected value ber 2002, vol. 01, issue 05), a high-capacity cargo
of aerodynamic efficiency was more than 32. plane concept dubbed Pelican is being developed
In recent years Lockheed Martin Aeronautical currently by Boeing Phantom Works [25], Fig. 27.
Systems investigated the development of what they It has a large-aspect-ratio main wing, a wingspan
call Sea-Based Aircraft [24]. LMAS calls for a move of 500 ft (153 m), a wing area of more than an acre
to hybrid aircraft compliant with a modern doctrine (0.4 ha), twice the dimensions of the world’s current
of rapidly moving smaller and lighter forces largest aircraft An-225, and it can transport up to
anywhere in the world, or standoff power projection 1400 tons of cargo.
on demand anywhere in the world. The LMAS It has a long trans-oceanic range and can fly as
search for appropriate hybrid solutions resulted in a low as 20 ft above the sea (span-based relative
family of designs. These include: seaplanes, float- ground clearance of the order of 20/500 ¼ 0.04), but
planes and WIG-like combined surface effects it is also able to fly at heights of 20,000 ft or higher.
aircraft—SEA, Fig. 26. Intended for commercial and military operators
LMAS concludes SEA is an emerging more who desire speed, worldwide range and high
effective alternative to WIG craft. throughput. As indicated by John Skoupa, senior
Whereas the latter manager for strategic development for Boeing
advanced lift and tankers ‘‘The Pelican stands as
the only identified means by which the US army can
is a ship that flies (specifically, the Russian
achieve its deployment transformation goals in
Ekranoplans),
deploying one division in 5 days or five divisions
has little altitude or maneuvering capability,
in 30 days anywhere in the world’’. It can carry 17
is sea-restricted,
M-1 main battle tanks on a single sortie.
has long takeoff roll,
Other applications are: as mother ship for
should be very large for the mission objectives,
unmanned vehicles, or as potential first-stage plat-
has no signature reduction capacity
form for piggybacking reusable space vehicles to
the former
appropriate launch altitude.
is an aircraft which operates on water,
The (extreme) GE provides larger range and
has aircraft altitude capability,
efficiency. The ‘‘Pelican’’ is foreseen to fly 10,000
has shorter takeoff roll than pure WIG aircraft,
nautical miles over water with a payload of 1.5
may be shaped for signature reduction,
million pounds. As flying in GE requires the latest
has reduced risk due to rogue waves and surface
flight control technology, the vehicle will be
obstacles.
equipped with reliable systems providing precise,
automatic altitude control and collision avoidance.
SEA combines multiple surface effect technologies It is worth mentioning that Pelican is a deja vu
in a Sea-Based Mobility Hybrid Aircraft design— concept. In the late sixties, Boeing was conducting
WIG, seaplane and hydroplane hull shaping. surface- intensive developments of an anti-submarine GE
effect ship hull shaping, ram and power-augmented vehicle named ‘‘Lowboy’’ configured as an airplane
lift, powered circulation lift and ski ship. According with low-mounted high-aspect-ratio wing. The
to LMAS, such a concept is viable with the current Pelican has been offered by Boeing as part of a
aircraft technology, and would provide speeds up to system solution that would include the C-17 Globe
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K.V. Rozhdestvensky / Progress in Aerospace Sciences 42 (2006) 211–283 223
Fig. 27. Cargo plane-in-ground effect concept ‘‘Pelican’’ (Boeing).
Fig. 29. Hydrofret 2 (concept, G. Gazuit and Y. Goupil).
master III transport, the CH-47 Chinook helicopter
and the advanced theater transport. for extending the airfields to water surfaces. In
fact, the authors of the concept, Gazuit and
3.5. Other projects and developments Goupil [27] advocate a specific formula for a sea-
plane, which features catamaran hull tandem wings
3.5.1. Sea-Bus project (European Community, large wing-like fuselage use of static (air cushion) and
surface-piercing hydrofoil-controlled WIG effect dynamic GE.
configurations) The concept is proposed in two versions. The first
The Sea Bus (project, 1997–2000) is basically a is a ram-wing catamaran complemented by a large-
large wing operating in GE just above the water aspect-ratio lifting forward wing (side wings) and a
surface which also features hydrofoils and a water- highly mounted large-aspect-ratio tail plane. In the
jet propulsion system [26], Fig. 28. The hydrofoils alternative version the tail wing is replaced by a
are positioned in a trimaran arrangement, and are large-aspect-ratio rear wing (side wings) forming a
connected to the air wing by vertical surface tandem with the forward wing, Fig. 29.
piercing struts. Separate V-shaped takeoff hydro- Deja vu: a seaplane design, combining a ram-
foils assist in generating lift force, thereby decreas- wing catamaran hull with a wing of large aspect
ing the takeoff speed at which the floating hulls of ratio (side wings), was proposed by R. Bartini in
the vehicle rise from the water. The main purpose of early 60s and is known as a Vertical-takeoff-
the hulls is to provide buoyancy in floating Amphibia (VVA-14). The goal was to provide
operations at low speed in harbors and in takeoff contact-free takeoff and landing of the seaplane.
and re-entry operations. Due to the large water The Hydrofret differs due to the second large-
density, the control of the vehicle by hydrofoils aspect-ratio wing element, highly mounted or
becomes more efficient in terms of shorter response located at the plane of the ram wing. A common
time. gain in both versions with respect to a ram-wing GE
It was hoped that the longitudinal stability would machine is that the overall aspect ratio of the system
be ensured by hydrofoils which implies redundancy is enlarged due to high-aspect-ratio wing elements.
of aerodynamic tail planes. It was required that the It appears that by properly adjusting relative
Sea-Bus should carry 800 passengers and 100 cars at position, pitch angle and areas of the large-aspect-
a cruise speed of 100 knots over a distance of ratio elements, one may provide static stability of
850 km. One of the key problems is the cavitation the vehicle when flying close to the water surface.
occurring on the hydrofoils at speeds exceeding 40 Additional reserve in this respect lies in special
knots. profiling of the ram wing in the longitudinal
direction (S-shaping and similar measures).
However, there may occur stability problems in
the transitional height range. Besides, while the
highly mounted tail in the first version of the
Hydrofret could have been seen as an unpleasant
necessity for GE machines proper, it appears to be
somewhat clumsy in free air flight which constitutes
Fig. 28. European Sea Bus project.
the main operational mode for the airplane.
3.5.2. Hydrofret concept 3.5.3. Multihulls with aerodynamic unloading
Proposed as a solution for the airport congestion A certain amount of work has been done on using
problem, the Hydrofret (Hydrofreight) concept calls the unloading effect of the presence of sea surface
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224 K.V. Rozhdestvensky / Progress in Aerospace Sciences 42 (2006) 211–283
on high-speed catamarans. Doctors call such developed by Professor Syozo Kubo from Tottori
catamarans ‘‘ekranocats’’ [28]. University and built with support of Mitsubishi
Somewhat earlier a similar concept of a Ram [30,31]. The m-Sky 1 (Marine Slider) first flew in
Augmented Catamaran (RAC) was also proposed 1988. This 1-seater craft had a square platform
by Gallington [29] who found that (obviously) the and endplates, TOW of 295 kg and L Â W Â H
most efficient power augmented craft should be dimensions of 4.4 m  3.5 m  2 m. Powered by a
touching water very little and cruise at high speeds. 64 hp engine driving a 4-bladed fixed-pitch air
In fact the RAC concept is a tradeoff between propeller, the craft could develop a cruising speed
increased drag of the side plates penetrating the of 82 km/h.
waves and the loss of lift and propulsion associated After the m-Sky 1 vehicle a more sizable 2-seat m-
with the lateral leakage of air. Sky 2 vehicle was developed and built by Mitsubishi
As reported, Incat Tasmania has been conducting under the supervision of Kubo [31], Fig. 32. While
tests of a manned model high-speed craft, ‘‘the almost similar to the previous craft, it had certain
Wing’’, that employs the WIG effect concept to distinctions: both air and water rudders, a wing
provide additional aerodynamic lift. Results of the structure made of aluminum pipes covered with
model tests have shown speeds in excess of 60 knots. cloth.
The test vessel is configured with three hulls (central The project of a 8-seater ‘‘flying wing’’ type craft
hull forward, outer hulls aft) supporting a delta started in 1998 by S. Kubo and H. Akimoto (of
wing superstructure, Fig. 30. Tottori University) with financial support from
A concept of a very fast ‘‘semi-WIG’’ wave-piercing Fukushima Shipbuilding Ltd and additional fund-
trimaran (WPT) making use of aerodynamic unload- ing (of the tests from April 2000 through April
ing of the hulls was developed by Dubrovsky, Fig. 31. 2001) from Shimane Prefecture [32], Fig. 5.2.19.
The concept of what they call Air-Assisted Vessel Takeoff weight 2.5 ton, dimensions L Â B Â H ¼
Solutions has been explored in a joint effort by 12 Â 8:5 Â 3:7 m, cruising speed of 150 km/h, the
Effect Ships International (ESI) and SES Europe expected range—over 350 km. Two water-cooled
AS (SE). ESI claims to have patented Air Supported reciprocal engines rated 250 PS each, installed in the
Vessel technology for both monohull and multihull middle of the central body, drive two three-bladed
vessels in 2002. They see it as an innovative propellers of 2 m diameter. The section of the main
approach to reduce hull resistance and improve wing is Munk M6R2 for the upper side and CJ-5 for
performance—suitable for various naval and com- the lower side. The resulting camberline of the wing
mercial applications. is S-shaped and the thickness is 9%. The center
body of the ship (hull, cabin and root parts of the
starboard and port halves of the main wing) is made
of FRP strengthened by aluminum pipes. It has a
step on the bottom and the rudder near the trailing
edge. Outer wings and tail unit are constructed from
aluminum pipes and covered by cloth. The outer
Fig. 30. A model of ekranocat tested in Australia. wings have endplates at the tips. The main wing
does not have a flap. The horizontal tail represents a
Fig. 31. Artist’s view of a 100-knot ‘‘semi-WIG’’ WPT ferry
designed to carry 600 passengers and 100 cars.
3.5.4. New Japanese WISE craft developments
A tendency of Japanese designs to have a simple
flying wing configuration started by Kawasaki Fig. 32. m-Sky 2 wing-in-surface effect (WISE) vehicle (S. Kubo,
KAGs was confirmed in the m-Sky vehicle series Mitsubishi).
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K.V. Rozhdestvensky / Progress in Aerospace Sciences 42 (2006) 211–283 225
stabilizer with elevator to adjust the angle of attack. length 29.5 m, width 19.6 m, propulsion 3046 kW Â 2
The vehicle has two vertical fins with air rudders. turboprop, maximum speed of 160 knots, with the
Japanese Canard WISES project: Kawasaki Jetfoil. The former has a transportation
The developers (from Tottori University, Japan) capacity 1.5 times that of the Jetfoil.
claim that a wing-tail configuration shows some
defect in takeoff, whereas the proposed canard 3.5.5. RotorWIG [34]
layout facilitates takeoff from rough seas [33]. They Rotor WIGs are characterized by a large over-
attempted to illustrate their idea by means of self- head rotor. The rotor allows for the third mode of
propelled model tests with 1.8 and 3.6 length models locomotion, positioned between the hull and the
(Kaien (storm petrel)-1 and 2). They state that wing. The rotor features tip weights that make up
WISES should have seaworthiness over 3.0 m wave about half of the total weight of the rotor system.
height for practical service in the seas around Japan. Before takeoff the rotor is over-rotated. Shortly
In the authors’ opinion, the canard scheme allows to after initiating the takeoff run, the pitch of the rotor
takeoff with high angle of incidence. In comparison, blades is increased and, within seconds, the craft
the wing-tail scheme does not allow large rotation leaves out of the water. Suddenly freed from any
angle without touching the water. They also think water drag, the air propellers accelerate the craft
that PAR ceases to be an effective liftoff aid in swiftly to cruising speed and it is the wing that takes
rough seas because the impinged air leaks easily over the lift from the rotor. During cruise, the rotor
from under-the-wing. The canard-type WISES used is off-loaded and its rpm allowed to drop to lower
by the authors has a forward mounted horizontal the drag quite drastically. For landing, the rotor
stabilizer (canard) and two propellers on it. The disc is held back to catch enough wind to act as an
elevator on the canard controls the pitching air break and increase its rpm. The energy in the
moment of the ship and the deflection angle of the over-rotated rotor is then spent to lower the craft
propeller wake. Vertical fins with air propellers are softly on the waves during flare with little if any
in the wake flow of the propellers. In the developers forward speed.
opinion, the merits of the concept are: The HeliFerry [34]:
RotorWIGs can be configured in many different
high angle of attack position results in a high lift ways to fit different mission objectives. HeliFerry
force, (HF) is a WIG version of HeliPlane, a twin pusher
high-speed wake from the props prevents both propeller rotorcraft of the size of a C-130 Lockheed
the canard and the main wing from stalling, even transport plane and specifically designed around the
in a high lift condition, Carter rotor system, Fig. 33. The HF is a double
the elevator and rudders are efficient even for decked rotorWIG based on a very slender hull
small forward speed because they are in the trimaran configuration. The low wing is of classic
propeller wake, Lippisch, reverse delta design. The other specifica-
propulsion systems always work in a spray-free tions are: length—118 ft, rotor radius—150 ft,
region. beam—70 ft, displacement—110,000 lbs, cruise
speed—120 knots at sea state 3. The rotor system
It is emphasized that the concept is better suited itself weighs 3 600 lbs, including the hub, pitch
for large WISES. The main wing of Kaien-2 has a linkages and the tip weights, its rpm ranges from a
profile of NACA3409s (NACA3409 with modified
camber line in rear part), whereas Kaien-1 had a
profile of ClarkY. The lift-to-drag ratio in cruise
was 6, i.e. somewhat lower than expected. Takeoff
speed was 6 m/s and cruising speed was 9.5 m/s. The
pitch angle in cruising was 4–51 and at takeoff—
2.5–3.51. In circular flight the mean roll angle was 51.
The maximum lift coefficient at takeoff (pitch up 151)
was 1.9, i.e. about 4 times larger than that in
cruising.
They compared their preliminary design of a
WISES for 140 passengers, displacement 56 tons, Fig. 33. HeliFerry—example of RotorWIG.
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226 K.V. Rozhdestvensky / Progress in Aerospace Sciences 42 (2006) 211–283
maximum in over-rotation of 125 to 85–100 no need for airports or runways,
required for full lift, to settle to 25 in cruise. no need for sealed cabins as required on strato-
spheric airplanes.
3.5.6. Korea WIG project [35]
Recently, it has been announced that the Korean 4.1. Civil applications
government plans to invest by 2010 in the develop-
ment of a large 300-ton WIG effect vehicle capable According to a preliminary analysis, as reported
of carrying 100-ton payload at a height of 1–5 m by Belavin [4], Volkov et al. [36] and Hooker [6],
above sea level. This WIG craft would have a length there exist encouraging prospects for developing
of 77 m, width of 65 m and would cruise at an commercial ekranoplans to carry passengers and/or
average speed of 250 km/h. The plan is to use it as a cargo, to be used for tourism and leisure as well as
next generation cargo ship to reach the neighboring for special purposes, such as search-and-rescue
countries or islands in South Korea. It could reach operations.
Qingdao, China from Inchon, South Korea in 3 h.
In particular, it would be useful for fast delivery of 4.1.1. Search-and-rescue operations
fresh vegetables and fruits. Korea Ocean Research Memories are still fresh about the tragedies that
and Development Institute has already finished a happened with the nuclear submarine ‘‘Komsomo-
successful test of a small four-seat WIG craft whose lets’’ on April 7, 1989 in the Norwegian Sea, and the
development started in 1995. A sketch of the nuclear submarine ‘‘Kursk’’ on August 12, 2000 in
Korean large WIG ship is presented in Fig. 34. the Barents sea.
An analysis of existing means of rescue on water
shows that surface ships are unable to come to the
place of disaster quickly enough, while airplanes
cannot perform effective rescue operations because
the airplanes cannot land close to a sinking ship.
Even most modern seaplanes have both lower
payload and seaworthiness as compared to the
ekranoplans. The GE search-and-rescue vehicle
‘‘Spasatel’’ is under construction at ‘‘Volga’’ plant
in Nizhniy Novgorod.
Fig. 34. Artist’s impression of Korean large WIG ship.
‘‘Spasatel’’, Fig. 35 which is based on the
‘‘Loon’’-type ekranoplan, combines features of all
4. Areas of application of WIG effect craft
known means of rescue on sea (search-and-rescue
airplanes, helicopters, ships). Its cruising speed is
Widely discussed, see Belavin [4], Volkov et al.
expected to be in the range of 400–550 km/h in GE,
[36] and Hooker [6], are such beneficial properties of
and up to 750 km/h out of GE. Altitude when flying
ekranoplans as:
far from the underlying surface would be up to
7500 m, and about 500 m in searching mode. The
cost effectiveness when properly designed and vehicle can land and conduct rescue operations in
sized, waves up to 3.5 m. It is capable of loitering in rough
high ride quality (low level of accelerations) in seas with wave heights reaching 4 m. ‘‘Spasatel’’ has
cruise mode,
impressive seaworthiness in takeoff and landing
and practically unlimited seaworthiness at cruise,
safety of operation due to the effect of ‘‘binding’’
to the underlying surface and also because ‘‘...the
airport is right beneath you...’’
amphibious capacity, i.e. ability to operate in GE
over water, land, snow or ice surface,
capacity of climbing an unprepared beach to
embark/disembark passengers or carry out the
maintenance of the vehicle, Fig. 35. Search-and-rescue ekranoplan ‘‘Spasatel’’.
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K.V. Rozhdestvensky / Progress in Aerospace Sciences 42 (2006) 211–283 227
a range of 3000 km, can operate autonomously for 5 The system implies that a search-and-rescue variant
days and is able to accommodate up to 500 people, of ‘‘Orlyonok’’ with improved seaworthiness and
see Denissov [37]. Before a decision todevelop special medical equipment is mounted on the back of
‘‘Spasatel’’ had been taken several experiments on the mammoth airplane AN-225 ‘‘Mria’’ to be
the available missile carrier ‘‘Loon’’ have been transported to the place of disaster at a speed of
performed to appraise the ekranoplan’s capacity 700 km/h. Upon arrival at the place of emergency the
to serve as a rescue vehicle. These experiments ekranoplan takes-off from AN-225, descends and
showed that ekranoplans have some useful features lands on the water surface to turn into a seagoing
justifying their use for rescue operations on the rescue vessel. Note that due to the considerable
water. In particular, when drifting on water the strength of its structure the ekranoplan can land in
vehicle is naturally brought to a position with its rough seas, which is dangerous for seaplanes.
nose against the wind. As the vehicle’s main wing is
partially (with its aft part) immersed in the water, 4.1.2. Global Sea Rescue System [38]
there forms a region of relatively calm water behind There is a worldwide concern to develop effective
it. The upper side of the main wing can be used as a rescue measures on the high seas. Experience shows
platform for embarkation of lifeboats and people that it is very difficult if not impossible to provide
from the water surface, Fig. 36. timely aid at wreckages and ecological disasters at
The CHDB in Nizhniy Novgorod and the Ukrai- sea. Use of seaplanes is often limited because of
nian aviation enterprise ‘‘Antonov’’ jointly studied unfavorable meteorological conditions, whereas use
the possibility of developing a unique large search- of helicopters is restricted to coastal areas. Until
and-rescue system which combines the long-range now, the main means of rescue (salvage) on water
and high-speed capability of a large airplane with the has been ships finding themselves accidentally near
life-saving features of ekranoplans in the sea, Fig. 37. the disaster area and hardly suitable for this
purpose.
A global sea rescue system is proposed, compris-
ing 50 heavy weight ekranoplans, basing in 12
selected focal base-ports throughout the world.
Each ekranoplan of the system is designed to have
high takeoff/touchdown seaworthiness, correspond-
ing to sea state 5 and enabling its operation on the
open sea during 95% of the time year around. The
cruise speed of each ekranoplan of the system is
400–500 km/h and the radius of operation constitu-
tes 3000–4000 km. The vehicle can loiter for a long
Fig. 36. Artist’s impression of rescue operations with ekrano- time upon the sea surface when seaborne at a speed
plan. of 15 knots. The rescue vehicle is supposed to bring
to the place of disaster a wide array of rescue means
including rafts and self-propelled cutters and,
possibly, helicopters and bathysphere.
4.1.3. Horizontal launch of the aerospace plane
According to the project developed jointly by
Musashi and Tokyo Institutes of Technology
[39,40], an unmanned self-propelled ekranoplan is
supposed to carry, accelerate to almost half sound
speed and launch a 600-ton rocket plane to a low
earth orbit (horizontal launch), see Fig. 38.
Launching useful payloads into low earth orbit
and expanding the functional capacity of the
aerospace transport systems is one of the major
Fig. 37. A search-and-rescue complex combining the ‘‘Mria’’ and tasks of the developers of new space projects for the
‘‘Orlyonok’’ (Project). 21st century.
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228 K.V. Rozhdestvensky / Progress in Aerospace Sciences 42 (2006) 211–283
deploying hydrophones or towed arrays. They can
also be used in a wide variety of reconnaissance and
transport roles. WIG effect vehicles could adapt
themselves to an operational concept of anchorages
all over the world to maintain a forward posture.
4.2.1. Anti-surface warfare
Fig. 38. Ekranoplan-rocket plane horizontal launch. Sustained sea-level operations of ekranoplans
would reduce the horizon-limited detection ranges
of defending airborne early warning systems,
4.1.4. Other civil applications significantly reducing warning time. If the defender
Other potential special areas are the replacement has no airborne early warning assets, mast height
of crews of fishing vessels, geophysical surveys, ship radars would not see the ekranoplan until it
express delivery of mail and parcels over the ocean; almost reached its target.
coast guard and customs control operations. Ekra- Back in 1966 the company ‘‘Grumman’’ devel-
noplans of moderate sizes can be used to service oped a project of a 300-ton WIG effect missile
coastal waters and to support transportation carrier configured as a flying wing with in-flight
systems of archipelagos, carrying passengers and variable geometry, the latter being achieved due to a
tropical fruits, fresh fish, etc. Similar considerations peculiar design of endplate floats [4]. This project is
can be found in Kubo [41]. shown schematically in Fig. 39.
As per Hooker, the ultra-large vehicles of ‘‘Wing- Another example of a missile carrying strike
ship’’ type offer many commercial possibilities, such as ekranoplan is ‘‘Loon’’ with 6 dorsally mounted
‘‘Mosquito’’-type missiles.
transportation of non-standard commercial pay- From operational and tactical viewpoints, the
loads of large sizes and weights, ekranoplan has incontestable advantages versus any
search-and-rescue operations of large scale other missile-carrying platform, in particular
transportation of perishable goods in quantity
throughout the world, ekranoplan speeds exceed by an order of
high-speed luxury transportation, magnitude those of conventional surface ships.
rapid response to international market fluctua- Unlike aircraft, the ekranoplan is not tied to
tions. airports or aircraft carriers and can be disper-
sively based in any coastal area,
unlike aircraft, the ekranoplan is less visible, flies
4.2. Naval applications in immediate proximity to the water surface, and
has large combat payloads (60 tons for the
Analysis of known projects and future naval ‘‘Loon’’). Due to its additional capability to
applications have confirmed that the above listed conduct flight operations far from the underlying
properties of ekranoplans together with their high surface, the ekranoplan can perform self-target-
surprise factor due to speed, low radar visibility, sea ing for larger ranges.
keeping capability, payload fraction comparable to
similar size ships, dash speed feature and capacity to
loiter afloat in the open ocean make them perfect
multi-mission weapons platforms which can be
deployed forward and operate from tenders, see
Belavin [4], Sommer [42].
Naval ekranoplans can be used as strike warfare
weapons against land and seaborne targets, launch
platforms for tactical and strategic cruise missiles,
aircraft carriers and amphibious assault transport
vehicles. Easy alighting at moderate sea states
makes it possible to utilize ekranoplans as anti- Fig. 39. Missile WIG vehicle developed by ‘‘Grumman’’ (Pro-
submarine warfare planes capable of effectively ject).
![ARTICLE IN PRESS
212 K.V. Rozhdestvensky / Progress in Aerospace Sciences 42 (2006) 211–283
3.5.3. Multihulls with aerodynamic unloading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223
3.5.4. New Japanese WISE craft developments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
3.5.5. RotorWIG [34]. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
3.5.6. Korea WIG project [35] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226
4. Areas of application of WIG effect craft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226
4.1. Civil applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226
4.1.1. Search-and-rescue operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226
4.1.2. Global Sea Rescue System [38] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227
4.1.3. Horizontal launch of the aerospace plane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227
4.1.4. Other civil applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228
4.2. Naval applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228
4.2.1. Anti-surface warfare . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228
4.2.2. Anti-submarine warfare. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
4.2.3. Amphibious warfare . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
4.2.4. Sea lift. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
4.2.5. Nuclear warfare . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
4.2.6. Reconnaissance and Patrol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
4.2.7. ‘‘Wingship’’ naval missions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230
5. Classification of WIG effect craft and some design parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230
5.1. Classification of WIG effect craft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230
5.1.1. By aerodynamic configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230
5.1.2. By altitude range: A, B and C types (IMO classification) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232
5.1.3. By physics of the GE phenomena. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232
5.2. Some design parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232
6. Aerodynamic aspects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
6.1. Lift, drag and their ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
6.2. Influence of geometry and aerodynamic configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
6.3. Influence of endplates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
6.4. Influence of the planform and the aspect ratio. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
6.5. Influence of waves in cruising flight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236
6.6. Compressibility effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237
6.7. Aero-elastic effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237
6.8. Peculiarities of the aerodynamics of formation flight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
7. Mathematical modeling of aerodynamics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
8. Stability of longitudinal motion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
9. Takeoff of WIG effect vehicles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246
9.1. Lift coefficient at takeoff . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246
9.2. Liftoff devices and solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247
9.3. Power augmentation for takeoff and cruising . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
9.3.1. PAR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
9.3.2. USB PARWIG concept. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
10. Structural design, weights and materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252
11. Control systems [12,117]. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253
12. Economics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256
13. Certification of WIG effect vehicles [119–122] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257
13.1. Ship or airplane?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257
13.2. Some hydrofoil experience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258
13.3. Progress in the development of regulations for WIG effect vehicles . . . . . . . . . . . . . . . . . . . . . . . . . . 259
13.4. Main features of the ‘‘Interim Guidelines for Wing-In-Ground (WIG) Craft’’ . . . . . . . . . . . . . . . . . . 260
13.5. NAV Sub-Committee amendments to the COLREGs-72 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261
13.6. Emerging requirements on knowledge, skill and training for officers on WIG craft . . . . . . . . . . . . . . . 261
13.7. First rules of classification and safety for small commercial ekranoplan . . . . . . . . . . . . . . . . . . . . . . . 261
14. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
14.1. Technical feasibility. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
14.2. Technical problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
14.3. Aerodynamic configurations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)