A Racing Adventure with EPS B&W Loudspeakers made its first foray into the revived sport of Gravity Racing last year; a hastily prepared entry won a surprise second place at Goodwood Festival of Speed Soapbox Challenge. This year, the pressure was on to go one better. The Soapbox Challenge, now in its third year, has become one of the most popular events of July's Festival. Strict rules govern maximum weight, length and width, together with a stipulated minimum eye level. There is also a £1000 limit on the cost of materials and the requirement for rudimentary brakes (although no-one intends to use them!). The cars race in pairs down the twisty hill climb circuit using the force of gravity alone.
Stuart Nevill from the engineering team at B&W Loudspeakers told EPS NEWS, what a key role EPS played in the making of the B&W entry and how it fared at this year's Goodwood Festival of Speed. "The B&W team — which comprised of Graham Paine and Pete Brook, from the B&W drawing office, Steve Marks from the model shop and Tom O'Brien and myself, Stuart Nevill, (also the driver) —designed and constructed a lightweight steel spaceframe chassis. The work was carried out during lunch hours and evenings over the course of a few months. "Initial trials of the naked chassis at the first official test day confirmed the new design to be inherently fast and totally stable, if a little loose at the rear end. "We opted to go for a composite bodywork. B&W's model shop has produced composite moulds for loudspeakers in the past but nothing on a 'vehicular' scale. We elected to go for a technique using stacked 2-D shapes of some workable material to create a full size mould plug. "Our friends at Linpac Moulded Foams very kindly cut us appropriately sized sheets of expanded polystyrene (EPS) using printed outlines we supplied as templates to cut the EPS to the right size. The EPS was then stacked and bonded to give us a representation of our final shape. "Using hot wires and sandpaper we carefully transformed the rough shape into a smoother and sleeker form, EPS greatly accelerated the otherwise painfully slow process because it is so easy to work and has a surprisingly smooth finish. Emulsion was painted over the top of the EPS form and any remaining roughness was filled with Plaster of Paris, followed with more sanding and more filling and so on until all the surfaces were smooth. "With EPS, you have two easy options for removing the plug from the 'shell or mould; either burn it out with acetone or rip it out with your hands, we chose the latter, any remnants were simply removed with a water jet. "We (just) managed to get the vehicle finished in time for Friday's practice. The 'box, named "Loudspeedster" really looked like it could be a winner — the opposition certainly thought so too. "Unfortunately, Friday was damp so our only chance to get a full speed test run was reduced to a slippery tip-toe down a greasy track. So, come Saturday and the first race day (Saturday and Sunday times were combined), we still had no indication of the 'box's speed.... "Which was, frankly too fast, the famous Moulecombe Corner was approached — even whilst handbraking — at 60mph and the result was, quite naturally, a great crowd-pleaser of a tail-sliding, twowheeling, barrel-roll off the Earl of March's straw bales, embarrassed driver relatively unscathed, but race over. "Rolls-Royce won, McLaren got the fastest time and we took an oddly twisted mess of many, many hours' work home with our unopened magnum of Veuves-Cliques but, as they say, "that's racing". "There's always next year!"
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