Thursday, March 12, 2009
For most of us, the world deep below the ocean�s surface remains a
place we have only had the pleasure to experience vicariously,
primarily through watching nature documentaries. It's not as if we can
just hop in a submarine and go take a look. Well, perhaps we can, if a
Russian company's plan to market a two-seater submarine driven by
pedal power to the tourist industry is successful. The new underwater
vehicle (UV) from Marine Innovation Technologies (MIT) will not only
be cheaper to buy and run than existing submersibles, it will be
simpler to operate, requiring no special training or expertise.
According to MIT, its underwater craft differs from comparable small
tourist submarines in overcoming some of the difficulties associated
with the use of traditional screw propulsion and accumulator batteries
to generate motion. These kinds of submarine tend to be complex to
control and service and require specialized training to operate.
Generally, submarines require a propulsion capacity of about 2.5�5 kW
to maintain an underwater speed of 2-3 knots. The average person
riding a bicycle struggles to generate a propulsion capacity greater
than 0.2-0.4 kW over a one to three-hour time period. This means a
pair of furiously pedaling tourists couldn't muster enough power to
propel an underwater vehicle.
But MIT has overcome the mathematical impossibility through both its
innovative design as well as something called the Coanda effect. With
both these elements in play, an average person, with the help of
pedals, can generate the necessary underwater speed of between two and
three knots, for two to four hours, to propel the company's
two-passenger UV.
So what is this miraculous Coanda effect the company has employed? It
is a phenomenon where a jet flow attaches itself to a nearby surface
and remains attached even when the surface curves away from the
direction of the initial jet flow. Run a stream of water over the
underside of a spoon and watch as the water follows the curve instead
of dropping straight down � that�s the Coanda effect.
In the same way, MIT's design uses rotor-jet propellers to take
advantage of the Coanda effect. The propellers direct an air jet
through a flat slot, in a tangential direction, onto the surface of
the vehicle, where it adheres and generates thrust. The disc shape of
the UV also helps to create a vacuum on the hull of the vehicle to
provide additional draught. According to the St Petersburg State
Marine Engineering University (SPbGMTU), which has been carrying out
tests on the UV's design, this enables two people, still producing
power of less than 0.4�0.8 kW, to generate the required speed of 2-3
knots for between two and four hours.
Its breakthrough design has allowed MIT to simplify the vehicle�s
construction and operation, which has also helped to keep the cost of
production down. The vehicle is small enough to be transported on the
back of a car trailer. It measures 11.5 feet (3.5m) long, 4 feet
(1.2m) high and 6.5 feet (2m) wide and weighs between 1.5 and 2 tons
out of the water.
In the water, the UV can reach speeds of 2�5 knots on the surface and
speeds of 2�3 knots under the water at depths of up to 30m. For those
who don't fancy pedaling, MIT will also offer an optional low-power,
combined electric drive.
The developers have also made sure the UV is simple to operate, with
only foot pedals, steering wheel and minimal buttons and indicators to
worry about. The onboard systems are also designed to function both in
manual and automatic modes. Safety features include an automatic and
mechanical drive for the release of ballast for surfacing in an
emergency.
The vehicle also boasts a high degree of maneuverability: it can go
forwards, backwards, up and down, hover and rotate about its vertical
axis. Passengers will also be treated to spectacular underwater views
with almost all of the UV's body transparent.
MIT is banking on the UV's relatively cheap price tag of between
USD$30,000-$70,000, as well as its cheaper cost to operate and
service, to find a market. Existing small submarines can range in
price, from USD$100,000 to USD$200,000, and cost more to service due
to their more complex mechanics. They also tend to require specialist
training to operate.
It is not only the tourist market MIT is hoping to break into. It
anticipates the UV will attract interest for uses in scientific
research, underwater filming, technical survey of underwater
structures, such as dams and pipelines, and underwater rescue.
Preliminary market research, carried out by MIT, suggests worldwide
sales of the vehicle may go beyond 1 million units. MIT is seeking
investors to fund the building of a prototype UV before establishing
manufacturing facilities. Once in production, MIT expects to produce
10,000 vehicles a year.
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