Looking for adventure? How about a frolic in your own personal submarine hundreds of feet below the surface of the ocean?
If you've got the cash - by some reports about a million dollars - Hawkes Ocean Technologies
(HOT) can put you in the driver's seat. The San Francisco area company,
which has designed and built the majority of the world's manned
submersibles since the 1970s, is getting ready to debut its most
advanced vessel yet, the Super Falcon, in the Spring of 2008.
Blending a sleek winged design with advanced mechatronics' concepts,
the craft promises to meet company founder Graham Hawkes' goal of
pushing the envelope in "deep water flight."
Tracing the Pedigree
The Super Falcon follows a 30-year history of designing and building
subs. Originally, Hawkes focused on Atmospheric Diving Systems, such as
the Wasp and Mantis, for the offshore oil and gas industry. Then he
moved to conventional submersibles he called Deep Rovers. In the late
1980s, Hawkes and his team shifted to winged designs, which embodied a
new generation of lightweight micro-submersibles that require no
ballast and operate on the same principles as flight through air.
"Super Falcon is the third generation vehicle in our line of Deep
Flight winged submersibles," says Hawkes. "The wings came about
originally because of our interest in building a full ocean-depth
vehicle as an alternative to a massively heavy conventional
submersible. When we launched our first winged sub, Deep Flight I, and
saw the public interest in underwater flight, we realized we wanted to
pursue underwater flight for its own sake, regardless of depth."
As Hawkes tells it, Super Falcon is "leaps ahead" of the company's
prototype flier, Deep Flight Aviator. "When you are trying to push the
frontiers of design, you either focus on the concept; keeping the
technology conventional, which is what we did with Deep Flight Aviator,
or you can push the technology," Hawkes says.
Geometry Shapes Performance
The Super Falcon will weigh about 4,200 lb and is designed as a
two-person performance submersible. Like HOT's previous submersibles,
it is always positively buoyant and has no variable ballast system.
Instead, the craft relies on hydrodynamic forces on its wings to fly
beneath the waves. This provides an inherent safety feature, says
Mechanical Engineer Adam Wright. If the sub were to ever lose power or
get into trouble, it would float back to the surface.
Only the pilot and co-pilot and a small amount of life support and
control hardware are encapsulated in the main pressure hull. All other
components, such as thrusters, actuators and batteries, are either
designed to operate under pressure or are housed independently. This
minimizes the volume of the pressure hull, which in turn reduces the
total surface area subject to hydrostatic pressure and keeps weight
For increased performance, the team designed the shape of the
pressure hull to minimize frontal area, while still maintaining
passenger comfort. As such, the geometry of the pressure hull is
inefficient at withstanding ocean pressure compared to conventional
geometrical shapes such as spheres or cylinders. To compensate, the
pressure hull will be constructed of very strong carbon
fiber/fiberglass composites and will maintain a safety factor of three
with an operational depth of 400 to 1,500 ft.
For propulsion, the sub relies on a large diameter dc brushed motor
powered by pressure-compensated lithium polymer batteries. A single
electric thruster can generate up to 500 lb of thrust. The sub will
cruise at an estimated maximum horizontal velocity of 7 knots, with a
much greater vertical ascent velocity. An independent ball screw linear
actuator will control each axis of flight control (pitch, roll and yaw).
"The sub will fly by wire, in that the flight controls are driven by
electrical signals instead of mechanically, which would have required
reciprocating seals in the pressure hull," says Wright.
Because the sub is designed purely to explore underwater flight, it
will not have a "hover" mode and will always need to maintain some
speed to stay submerged. As a result, it will not carry any
manipulator, although future research-based submersibles will have
manipulators and be capable of hovering.
Safety in the Deep
In designing the sub's electrical and control systems, the major
concerns were safety, reliability, flexibility and accessibility,
according to lead Electronics Engineer David Jeffrey. "Because we're
working around seawater and because there will be crew and divers in
the water during submarine operations, it is dangerous to have high
voltages," he says. "Our submarine runs on a 50.4V battery power
system, heavily monitored during maintenance and operation. This is a
good compromise between excessive voltages and having to handle very
Jeffrey adds, the best design electronics approach is to "minimize
the things that experience tells us tend to go wrong." In submarines,
this mainly involves areas where electronics and seawater can come
together, such as underwater connectors and sealed one-atmosphere
housings, particularly if they have a moving seal. Static seals perform
far better, says Jeffrey, as do brushless dc motors, which can run in
an oil-filled housing at ambient pressure.
Since the team wanted to limit the number of wires passed between
the exterior and interior of the sub, the engineers realized a
networked control system, based on standard modules, would work best.
That solution also addresses accessibility issues. The sub has a
"diagnostic port," which permits a PC to communicate with all of the
nodes. Everything sub pilots might want to adjust is stored in EEPROM
in the nodes and can be read and changed as needed. Using a bootload
program, one can even upload a whole new suite of software to the nodes.
Another huge advantage of a network, according to Jeffrey, is that
it can be extended. Adding a node does not require adding wires. This
is a great improvement over the old, hard-wired systems, which used
preset potentiometers for all adjustments and separate wires for every
Essential Design Tools
To bring all these design innovations to life, the HOT team turned
to a full suite of software tools. For mechanical work, the engineers
relied heavily on Autodesk Inventor Professional 11. "The software
allowed us to model a design rapidly to a conceptual stage that could
be viewed in 3D by all members of the team," says Mechanical Engineer
Wright. "This allowed everyone to pitch in their ideas."
Also very valuable, adds Wright, were ANSYS Mechanical (FEA stress analysis simulation software) and ANSYS CFX (computational
fluid dynamics software). "Because the shape of the pressure hull is so
unconventional and organic, one cannot easily calculate its internal
stresses or interaction with other components," he says. "But with
ANSYS Mechanical, we can iterate different designs and get visual
results within minutes."
For the electronics design, Jeffrey did most of his general drawing with Zoner Draw 5, a low-cost package he has used for many years. He also does PCB design with BoardMaker3 and for AVR microcontroller software, he uses Atmel's AVR Studio and CodeVisionAVR compiler.
AVR Studio supports two different methods of de-bugging. "You can run
your code in an emulator on a PC or you can use a JTAG interface to
permit debugging in the target hardware," says Jeffrey.
The team developed most of its PC software for the sub using Just BASIC and Visual Basic.
They also turned to Just BASIC to develop network diagnostic and
monitoring programs. Terminal v1.9b by Bray was an important serial
port diagnostic tool. Among other useful tools cited by Jeffrey: PSPad for program editing, WizFlow for generating flow charts, MultiSim for simulating board hardware performance and MathCAD for modeling stepper motor controls.
In addition, Electronics Engineer Charles Chiau relied on Autodesk Maya 8.5 for
underwater lighting simulations. By importing the model from Autodesk
Inventor and placing a simple camera in the cockpit simulating the
pilot's perspectives, engineers were able to create artificial
underwater environments and test various configurations of the lights
on the Super Falcon. "This software was a great tool for giving us a
feel for what the sub's pilots would see," says Chiau.
Hawkes points out that this rich lineup of computer tools enabled
HOT to reduce the Super Falcon design team to the bare minimum, four or
five engineers. "Once you get down to that number, the communications
issues that plague bigger teams just don't exist," he says.
Chiau also cites the importance of weekly brainstorming sessions
involving a team from a variety of engineering backgrounds. "It is
extremely important that we collaborate because our subs are a fusion
of electrical and mechanical components," he says.
Chasing the Market
Tom Perkins, founder of the venture capital firm Kleiner Perkins,
will be the first owner of a Super Falcon. The sub will be operated
from his sailing yacht, The Maltese Falcon. "Tom is truly pioneering
underwater flight with us," says Hawkes.
And the cost? "If you have to ask how much, then you cannot afford
them!" adds Hawkes. "But we hope to eventually get our costs down to
the range of the light aviation industry. We're always looking at ways
to reduce costs, including licensing the technology to a qualified
The HOT team is already working on what Hawkes describes as an
"extreme submersible with extraordinary performance capability beyond
anything that exists." This project may be announced before the end of
As Hawkes explains it, about two thirds of our planet is covered by
water, yet there are only five deep submersibles in the entire world.
To give customers more choice, Hawkers has started a company called
Ocean Access International (OAI) and is raising venture capital money
to make the firm's Deep Flight submersibles widely available for
science, governments and industry.