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The
Development of the X-113 Ground Effect Craft
 Dr Lippisch's reverse delta wing aerofoil
flying boats were an attempt
to combine the
efficiency of ground-effect with long range and speed. Dr Lippisch's
invention provides a vehicle that operates efficiently both on the
water and
in the air and is particularly efficient in performance in the region
of
ground effect. Another objective of his invention is to provide a
ground effect craft which makes an efficient transition from the
waterborne state to the airborne ground effect state and also
capable of operation as an aircraft at higher altitudes completely out
of the ground effect. Dr Lippisch performed a series of wind-tunnel and
tow tank tests on low
aspect-ratio wing in
ground effect and found that they showed favorable
characteristics. In one of his technical papers, Dr Lippisch stated
that the drag measurements of the X-112 aerofoilboat in tow of a motor
boat, the resistance after take off from the water surface was 20 lb at
a gross weight of 510 lb which corresponds to an L/D ratio of 25.5. At the
Collins Hydrodynamic Laboratory the X-112 was built from balsa wood and
test flown during the fall of 1963 carrying the civil registration
N5961V in the united states. Despite the
fact that the X-112 was
built from balsa wood, it was successfully operated in ground effect
even with 2 persons on board.
 After
these US trials, Dr Lippisch returned to Germany. Encouraged, Lippisch founded
the Lippisch Research Corporation In
1966, and
became a
consultant to Rhein Flugzeugbau GmbH(RFB), a subsidiary of Fokker-VFW
in Germany. Dr Lippisch
started to design another larger proof-of-concept craft X-113 with Mr
Hanno Fischer, the Technical
Director of RFB. The X-113 was designed to operate out of ground effect
to meet the military specifications and requirements. It was built
completely from GRP material, which proved to be an ideal material for
water based crafts. The X-113, fitted with a 48HP Nelson H63-CP
four-cylinder piston engine, and carrying the civil registration
D-9568, made its maiden flight in October 1970 from Lake Constance. The
X113 test flight was successful and was even capable to fly out of
ground effect up to an altitude of 800m, however, at an excessive full
engine power setting and fuel consumption as penalty.
 Based on
the experience with the X-113, Mr Hanno Fischer at RFB Rhein
Flugzeugbau GmbH designed the lager X-114, based on a specification of
the
German Navy. The X-114 has a low aspect ratio reverse delta wing
of approximately 1.5, and adopted the Catamaran design without hull at the fuselage, which is
different from
the trimaran like the X-112 and X-113. It was a 6-seater craft capable
of cruising in
ground effect as well as in free flight. X114 was fitted with a
Lycoming IO-360 4 cylinder piston aircraft engine driving a shrouded
pusher propeller and has superior
maneuverability distinguishes it from hovercraft and has an interesting
"jump and turn" capability. It was flown for the first time in April
1977 carring the military markings 98 # 29. A later improved version,
the X-114H, was incorporated retractable hydrofoils to decrease the
take-off length.
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| X-113 Specifications |
Dimensions
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Total
length
Total width
Height
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8.43 m
5.89 m
1.98
m |
| Weights |
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Empty
MTOW
Payload
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260 kg
389 kg
80
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| Propulsion |
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Engine Power
Fuel
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48 HP
Regular fuel
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| Performance |
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Take
off speed
Take off wave
height
Cruise speed
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60 Km/h
0.5 m
140 km/h
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X-113 Design Characteristics
The craft is designed to set relatively flat in the water when at rest. As the craft
moves through the water with increasing speed, the
water and air cushion pressure built up beneath the wings. This causes
the craft to move upwardly and planing on the bottom parts of the hull
and sponsons, without shifting the hydrodynamic upward pressure center while still in planing
contact with the water. Manwhile the differential in pressure
built up between the wings surfaces and the air pocket formed under the
wings produce increased lifting force with increasing speed.
Because the centers of both lift and pressure of the craft are substantially coincide, the craft is inherently stable
during the water-to-air transition. Therefore the craft operates
efficiently both in the water and in the ground effect, as well as in
free flight.
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New Home for the
Lippisch's X-113 ground effect craft
In
view of the important role that X-113
had contributed to the development
history of the reverse delta Lippisch design wing-in-ground effect technology,
Wigetworks has donated the X-113 to the School
of Engineering of Ngee Ann Polytechnic in Singapore for
the academic research and educational purpose. The X-113 is currently
standing proudly at the
School's
Aerospace Hub, lecturing the young students the beauty of the ground
effect phonomenum and inspiring our future scientics and engineers to
continue to write and
explore new chapters for the ground effect technology.
X-113 received a gentle and encouragement
touch from an old friend.
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Copyright
Wigetworks Pte Ltd. All Rights Reserved
 123
Genting Lane #05-04 Yenom Industrial
Building Singapore 349574
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