Software expedites submersible design

Richmond, CA--By leveraging the capabilities of advanced CAE software, designers of a new high-performance submersible were able to achieve an impressive four-month design-to-manufacture cycle. Though they had previously designed vehicles using AutoCAD's 2D capabilities, the engineers found that by using Autodesk's Mechanical Desktop they could not only expedite the design, but also get a better idea of what the final product would look like before building a prototype.

Called Wet Flight, the craft is the latest high-performance underwater vehicle to swim out the door at Hawkes Ocean Technologies (HOT). It's an innovative, one-person, wet (scuba diver-piloted) submersible designed as a mobile camera platform for underwater cinematography. Performance is said to exceed that of previous wet submersibles. With 14-hp thrusters, the 11-ft, 2-inch long craft can "fly" through the water at up to six knots. Stubby wings endow the 1,500-lb submersible with impressive maneuverability.

The craft and the company are the offspring of Graham Hawkes, recipient of Design News' Special Achievement Award in March 1997. He's designer of many of the world's finest submersibles and creator of Deep Flight, HOT's flagship submersible capable of diving to 1,000 meters.

While Deep Flight and Wet Flight are similar vehicles, they were designed in quite different ways. "From an engineering perspective, the design of Wet Flight was the first time we used Mechanical Desktop," says Eric Hobson, HOT mechanical engineer. Team members exploited a suite of Autodesk tools, using Mechanical Desktop for 3D design and AutoVision and 3D Studio for visualization studies. "Designing in 3D in real-time was a strong advantage on this project," he says.

A critical part of Wet Flight's design was obtaining visuals to keep the design on track. Throughout the development process, engineers were able to quickly obtain 3D models and renderings that accurately represented what the completed design would look like. "In real-time, we could make design decisions on the fly," Hobson says. "For us, this capability was a milestone."

Wet Flight is a smaller version of Deep Flight and uses many of the same components. Packaging these parts within a smaller structure presented some interesting challenges. Wet Flight's exposure to the elements also required housing the electronics in cylinders fixed to the sub's walls. The design process was simplified by exporting Deep Flight's AutoCAD files into Mechanical Desktop. Engineers then performed several iterations, evaluating several design variations before manufacturing a single part.

The submersible's frame is made from black polypropylene, which has a slight positive buoyancy. "It's an ideal material because of its buoyancy characteristics," Hobson says, "and it's lightweight yet strong and shock-resistant."

He used AutoCAD to draw the patterns for the frame, and plotted them full size to help cut wood templates. Polypropylene parts were then cut from the templates.

Wet Flight has already found application in the movie industry as an underwater camera platform for an IMAX special project called "Dolphins: The Ride."