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Gullwing doors
also known as
Deloren Doors or
Gull wing doors not - Lambo Doors
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What are Gullwing Doors?
The term gull-wing door is an
automotive industry term describing automobile doors which
are hinged at the roof. They are so named because, when
opened, the doors evoke the image of a seagull's wings.
Conventional car doors are typically hinged at the
front-facing edge of the door and allow the door to swing
outward from the body of the car.
The most well-known examples of road-cars with gull-wing
doors are the Mercedes-Benz 300SL from the 1950s, the
Bricklin SV-1 from the 1970s and the De Lorean DMC-12 from
the 1980s.
Practical Considerations
Despite the common misconception that the gull-wing doors
are mere stylistic affectations, the design is a very
practical one. The advantage is that when properly designed
and counterbalanced (for example, the De Lorean), they
require little side-clearance to open (about 27.5 cm, or 11"
in the De Lorean) and allow much better entrance/egress
than conventional doors. This is especially important for
vehicles like the De Lorean whose width would make
conventional doors awkward to use when the car
Gull-wing doors have a
somewhat questionable reputation because of early examples
like the Mercedes and the Bricklin. The 300 SL used the door
design to allow an unusual chassis design which required a
very high door sill and forced the doors to be smaller than
would otherwise have been optimal. The Bricklin was a more
conventional sized door but the actuation system was
problematic in day-to-day use and led to unreliable
operation. In addition, there was some concern that in
making the door as light as possible, it couldn't provide
adequate protection in side-impact accidents. There was,
however, no indication that this concern was justified.
The De Lorean solved these problems by using a solid-steel
torsion bar (supplied by Grumman Aircraft Engineering
Corporation) to counterbalance a full-sized door and then
used simple pneumatic struts similar to those found in
hatchback cars to open the doors and dampen the movement of
the doors.
Other disadvantages of the system were not so easy to
address. For example, the gull-wing design makes creating a
convertible version of the car virtually impossible since,
for optimal efficiency, the hinges must be placed as close
to the center of the car as possible. This was never a
concern for the De Lorean since no convertible version was
ever planned (though there were rumors of a four-door family
car based on a front-engine chassis with room for four
passengers).
It also makes sealing the car against water leaks more
difficult because of the shape and movement path of the door
itself. Many De Lorean owners report leakage when taking
their vehicles through automated car-washes because of the
high-pressure water jets, though in ordinary rainfall the
seals were more than adequate.
In addition to the traditional gull-wing doors, there are
other unusual door mechanisms - particularly among exotic
and expensive cars. Lamborghini uses a design which is a
hybrid of the conventional and gull-wing design which is
generally referred to as a "scissor", "jack-knife" in which
the door is still hinged at the front but swings upward from
the car while staying parallel with the edge.
The McLaren F1 roadcar and Mercedes-Benz SLR use a variant
of this system called Butterfly doors. The doors are hinged
at the front similar the scissor doors but the hinges are
placed higher up on the A-pillar, allowing the door to pivot
both up and out. This increases the ability of the door to
move out of the way of the car's occupants but does not
prevent a convertible version. The Toyota Sera was a
limited-release car designed exclusively for the Japanese
market which used this design. Due to its unusual design,
some enthusiasts in Australia, New Zealand and England have
privately imported the cars. It is available only in
right-hand drive configuration.
Koenigsegg uses a "dihedral synchro-helix" system for their
vehicles which seems to combine the advantages of all the
designs, though with considerably more mechanical
complexity.
The BMW Z1 used a novel design in which its doors were not
hinged at all but rather retracted vertically into the
chassis, leaving an empty (though unusually high) sill.
The kit car Nova/Sterling also known as Purvis
Eureka in Australia used a special type of door,
actually a lifting canopy, on several of their models where
the entire top section of the car was opened. The Saab
Aero-X used a similar design.
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