Smoke on the water

The world's water speed record has been held by an Australian for almost 30 years, which is much too long if you ask British writer Nigel Macknight. He's been planning a run at the water record, currently at 317.6 mph, since 1988. That's when he called famed engineer Ken Norris, the man behind the Bluebird cars and boats used by Donald Campbell in the 1950s and 60s to set land and water speed records.

Finally, after working, planning, and fundraising for 18 years, Macknight could be on the water in his new boat, Quicksilver, by next year and setting a record by the year after.

JET ENGINES AND SPACE FRAMES
It takes the power of a jet engine to send a boat over the water at speeds above 200 mph, and it takes a rigid and strong chassis or frame to hold that engine when it is spitting out more than 10,000 lb of thrust. Norris (who died last Oct. at age 84) designed Quicksilver as a follow-on to the 1950s Bluebird K7, a jet-powered boat built around a space frame or cage of metal supports and structural members. So the two boats are similar. "Except Quicksilver is 50% bigger, 50% heavier, and has twice the power," notes Macknight.

The power comes from a Rolls-Royce Spey jet engine, which once powered Buccaneers. Macknight and his team were lucky enough to buy two such engines at a 1998 auction. The deal even included a well-maintained Buccaneer aircraft that housed both engines.

The 10-ft long, 1.2-ton engine dictated the size of Quicksilver. It would be about 42-ft long and weigh 3.5 tons. This suited chief designer Norris, who felt a 300-mph boat would have to be longer than previous recordholding boats if it were to remain stable at the higher speeds. There are some worries, however, that the boat may be too heavy to get up to speed and set a record on the 5-mile-long Coniston Water, a lake in England. (Several records have been set at Coniston. Donald Campbell died there in a 300-mph crash in 1967. His body wasn't recovered until 2001.)

During a run, the boat will stay in displacement condition with its hull in the water to about 30 mph. From 30 to 70 mph, the hull transitions to planing condition with its hull mostly out of the water and drag reduced significantly.

The team also acquired three more Speys, one that runs and is installed in the boat, and two that don't and act as spare-part lockers. The team keeps its two best engines, with one a working spare, in the Buccaneer. These are periodically fired up to keep them in good working order until needed in Quicksilver.

The engine sits in a space frame designed by structural engineer Glynne Bowsher, the man who designed a similar frame for Campbell's ThrustSSC, currently the world's fastest car and the first to go supersonic in a record attempt. The 670-lb frame is constructed of 2-in.-square tubular members made of high-tensile steel. The team had to devise a new welding technique to fabricate the frame.

The Quicksilver team stores its two best engines in a working Buccaneer jet, the last all-British strike aircraft ever built. It was designed as a carrier-based, low-level bomber, so the engine can ingest some water, even seawater, and still operate.

"The space frame is a tried and tested method of supporting jet engines in one-off projects," says Macknight. "It might not be as light as a monocoque or unitary frame, but it is strong, manageable, and it lets us add components, wiring, and other accessories as we need to."

Mounting the engine in the frame is a critical task. Even though jet engines are inherently balanced and vibrate little compared to reciprocating engines, running on the water presents a challenge for the engine mounts. First, the ride will be bumpy, some water is likely to get to the engine, and changes in temperatures cause significant thermal growth in the mostly metal engine. "But all that shouldn't be a problem for Bowsher," says Macknight. "After all, he put two Spey engines in the SSC car and went supersonic. We're just asking him to put one Spey in a boat and go over 300 mph."

The jet pipe, the tubular section that aims the thrust out the back end of the boat, will be pointed straight back. Automotive racing teams that drag race with jet-powered cars mount engines in a slightly nose-down attitude. This keeps a small portion of the thrust pinning the car to the ground and preventing it from going airborne.

"If we put the jet pipe at an angle, it could be the wrong angle, and that could cause problems," explains Macknight, "We can always modify the pipe if we have to. It's removable. And the adapter for it can be changed as well."

The ability to change pipe hints at Quicksilver's modular design, a first for high-speed boats. "Going for a world speed record is always experimental, and this boat is a one-off. It serves as its own testbed and research vehicle," says Macknight. "Being modular lets us, for example, change out the nose, the lip to the air intake, or the aerodynamic surfaces of the boat. This gives it something in common with modern high-end race cars. You can tear one of those down and rebuild it almost overnight.

"The disadvantage is the weight penalty. We had to add bolts and hard points to put on and take off assemblies," he says. "But the penalty is acceptable because it lets us adapt the boat in the field and work out a development plan."

FINE-TUNING THE HULL
Because the Quicksilver team is learning as it goes, the final design for the boat is not frozen. The team is still doing wind-tunnel and water-tank testing with 1/ 8th scale models. The wind tunnel has a turning conveyor belt that simulates ground, or in this case, water, moving beneath the hull. The tank, a Ministry of Defence resource, measures a quarter of a mile long and is only good for replicating speeds up to 70 scale mph. "But that lets us go from 0 mph, the displacement condition with the hull completely in the water, through transition and to planing, with the boat skimming along the top of the water and almost none of the hull in the water.

"Water has 800 times the density of air, and drag increases with the square of the speed, so you'll never set a speed record with the boat hull in the water," explains Macknight. "You have to hydroplane above it and reduce the drag."

The team is also using radiocontrolled models to gather design data. "They can't carry much instrumentation, but you can take the models on a lake and hit relatively high speeds.

"We also use computer simulation and FEA," says Macknight. "Some on my team prefer doing everything on computers, others think you can do it all in wind tunnels and water tanks. But currently, the best method is to use all three and try to correlate data. If you get the same trends emerging from tank and tunnel testing, as well as computer simulations, it's a fairly positive indication you are getting accurate evidence.

"Computational abilities are increasing, and they may eventually replace tunnels and tanks. But we do tank and tunnel testing, then validate the data with computers," notes Macknight. "Once we know our model simulations are good, we do as much as we can on computer and double check results from the tunnel and tank. It's surprising how much work you can get done just keeping the computer crunching numbers all night."

Recently, the team redesigned the hull, making it slimmer for less weight and drag, and pushing forward the sponsons (pods that stick out of either side). At low speeds, the sponsons provide buoyancy while at high speeds, they stabilize the boat like outriggers on a canoe or training wheels on a bike.

Putting more weight up forward also gives the boat weathercock stability," says Macknight. "So the boat wants to move front end first. For example, if you throw a dart or an arrow, the forward weight and the shape tends to make them travel through the air point first. Similarly, Quicksilver at speed will 'want' to travel front end first."

The right-hand sponson is also planned as cockpit for Macknight as he pilots the boat. Though a bit cramped, it is large enough to hold Macknight, his helmet, oxygen mask and gear, and a steering wheel. The instrument panel carries little more than readouts and dials for the engine. Though the cockpit is off-center, visibility is good, especially since the four planing surfaces are aft of the cockpit. "They kick up a lot of spray, but it's all behind me," says Macknight. There's also thought of making the cockpit sponson detach in case of emergency, serving as a rescue pod for Macknight.

The boat is steered with a rudder mounted slightly off-center at the stern. It's mounted there to make room for the waterbrake, which acts like a parachute on a dragster to quickly slow the boat. It has to be in the center or else its off-center drag could corkscrew the boat and make it pitch over. The rudder will use speed sensitive steering. So at low speeds, the pilot might get 30° of rudder swing as he moves the steering wheel. At higher speeds, the pilot clicks into a finer mode, giving him perhaps 5° of swing for the same steering-wheel movement.

After more testing, the team might make the sponson thinner or change the air intake from a big, round maw to a more conventional set of twin inlets on either side of a cockpit. This would stop water getting into the engine at low speeds and stop the nose from plunging into the water as it slows from 300 mph. If it nosedives too quickly, it could overturn the boat.

SAFETY FIRST
Though it's usually mentioned last, the Quicksilver team is sure to mention that safety is first. Sponsors and the public aren't keen on sporting events that routinely end in death, "It's bad publicity and bad for sales," jokes Macknight.

He will be adding a host of safety devices, including HANS (head and neck restraint system), which has reduced head and spinal injuries in auto racing. Composites in the skin and hull will deform predictably in crashes to cushion major impacts. Another big improvement, especially for high-speed boating, is that sensors are now smaller. It will let the team stud the boat with small devices that track and report on the health of the boat. "Sensors will monitor and record the forces on the boat and the motions it is going though in real time," says Macknight. "So the pilot will know if the boat is approaching a dangerous regime and either counter it or avoid it all together."

"I want this to be on par with top-level auto racing, high-level aerobatics and mountaineering, not some death or glory kind of thing with a high-likelihood of fatalities," says Macknight. "We have to approach this with respect, and our policy is 'Safety First.' And safety isn't a euphemism for fear and trepidation, or an unwillingness to approach danger. Because, if you build safety in, you can actually go quicker. It can be a performance enhancer."