14s go airborne!

Aeronautics PhDs apply their logic to the sailing skiff

Tuesday April 1st 2003, Author: James Boyd, Location: United Kingdom
On a discreet lake in the depths of darkest Devon, top secret research work is currently underway on what looks set to be the latest development in the International 14 class.

The ‘She Was Only 14’ campaign of Tom Brown and Derek Smith, both currently finishing their PhDs at Cranfield College of Aeronautics, looks set to revolutionise foil development not only in the 14 class but in other spheres of yachting.

The use of T-foils on International 14 rudders is now commonplace. Brown and Smith’s first experiments were to put their own design of T-foil at the bottom of the centreboard too. Early results were impressive: in more than 12 knots of breeze the stern would start lift out of the boat and in 20 knots the hull was entirely clear of the water. “However stability became a problem,” commented Brown. “In gusts she would either just fall over or she would trip over the forward foil.”

Following one particularly nasty wipeout Brown and Smith decided it was time to return to their drawing boards. Their breakthrough came after watching Top Gun on video following a lengthy debrief in their local pub.

"There are two problems with using conventional foils," explains Brown. "Firstly they are very draggy before you get them up to operating speed and secondly they are in the water. With yacht design there is the constant headache of having to work in two media - water and air. You are constantly trying to get over the problem of hydrodynamic drag so we through why not have none at all? What if we make this baby airborne?’”

Starting with the premise that their International 14 should fly Brown and Smith set about designing a new ‘hull’ based a novel lightweight Delta-shaped wing while they worked on a completely new sail plan that would not only provide ‘thrust’ but ‘lift’ as well.

Inspiration for how to get their International 14 up to speed came partly through seeing Kelly McGillis ride her motorbike in full leathers, but more from Maverick and Goose launching their F-14 jets off the deck of an aircraft carrier. The duo approached the Taverton Rubber Company to design them a unique 100m long catapult. With their 14 mounted on a low friction trolley, they use the catapult, tensioned by attaching it to the tow bar of a Land Rover, to propel them along a specially-built launching ramp set up at the side of the lake. “By the time we leave the ramp we’re doing about 100 knots,” says Brown, who adds they were initially shaken by the G Force experienced during their launchings.

Initial tests were also hampered by simply getting their flying boat to withstand the acceleration. Early trials saw their boat disintegrate half way down the track causing the duo to leave half their backsides on the gravel beach as they skidded on and into the water. “That’s when we got the leather suits,” explains Brown.

With their wing vessel boat reconstructed with added carbon fibre stiffening, recent trials have proved more successful. They can now launch successfully and have made it to the weather mark. Latest experiments have been on techniques for making the return journey. Brown says they are considering the use of a rapid deployment sea anchor around with which they can slingshot themselves around the weather mark.

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