A flexible “bag” known as a fuel cell renders the traditional term, “fuel tank”, something of a misnomer. Quicksilver’s  fuel cell is capable of holding up to 277 litres of kerosene. Its construction is a composite of ballistic nylon and polyurethane. This provides crashworthy containment of the fuel, (a) because it is almost impossible to puncture or tear, and (b) because the cell will deform if impacted, allowing the fuel to “move away” from the source of the impact whilst still being safely contained.

     Within the cell’s interior is an arrangement of baffles, one-way gates and one-way valves which ensure that, as fuel is consumed during a run – and as the craft accelerates at the start of the run, causing the fuel load to “stack” against the cell’s back wall, and then decelerates at the end of the run, causing the remaining fuel to “stack” against the front wall – the fuel pump, which nestles inside the cell, will at all times be submersed in fuel, enabling it to maintain constant pick-up and ensure smooth fuel delivery to the engine, almost down to the last drop

     Virtually all of the inner volume of the fuel cell is packed with a special type of foam material which would prevent an explosion occurring in the extremely unlikely event of the cell being punctured or torn in a major accident. This material, which is known as ESF (explosion suppressant foam), only displaces 2.5 percent of the total internal volume of the cell, but this is sufficient to divide the ullage – the space that lies above the fuel, which is filled with a potentially volatile air/fuel vapour and increases in volume as fuel is consumed during a run – into a multitude of tiny voids, thereby rendering it harmless.

     As well as protecting against an explosion, the foam “stabilises” the fuel by limiting the extent to which it can slosh about in the cell when the boat is in motion. Sloshing effects could otherwise be detrimental to the craft’s stability and handling.

     The flexible fuel-line which conveys fuel from the cell to the engine is clearly visible in the image above. It is 35mm in diameter and is composed of an inner liner of extruded PTFE, wrapped in a fireproof Nomex pipe, with an abrasion-resistant fabric outer sheath.

     Quicksilver’s fuel system was purpose designed and manufactured for the craft by our long-standing technical associate, Advanced Fuel Systems Ltd., of Newport, Essex. Providing a graphic example of the close cooperation which exists between the Quicksilver team and its technical partners and associates, the squad’s fuel system specialist is the Managing Director of Advanced Fuel Systems, Jonathan Tubb. His company has a distinguished history in the speed-record field, having designed and manufactured the fuel system for Richard Noble’s ThrustSSC car, with which RAF Squadron Leader (now Wing Commander) Andy Green smashed the World Land Speed Record in 1997.

     Over its 15-year existence, Advanced Fuel Systems has produced more than 3,000 fuel cells for racing cars, exotic road-going cars, and aircraft and marine craft of extremely diverse types – many of them, like Quicksilver’s fuel cell, being purpose-designed.

     As the fuel system supplier to Richard Noble’s new BloodhoundSSC World Land Speed Record project, too, Advanced Fuel Systems is continuing a proud tradition of contribution to British engineering excellence. The company is supplying the fuel system for the target-1,000 mph car’s EJ200 Eurofighter Typhoon jet engine, as well as the fuel system for the car’s rocket-engine liquid propellant (oxidiser) pump, which is derived from a Cosworth CA 2010 Formula 1 engine.

Quicksilver’s fuel cell is located immediately behind the craft’s Rolls-Royce Spey engine. Siting the fuel load relatively well back in the hull brings about a forward migration of the craft’s centre-of-gravity as the fuel is consumed during the course of a run, thereby increasing the “weight on water” at the front planing surfaces as the craft accelerates along the lake. This aids dynamic stability, increasing safety margins at higher speeds.

     Furthermore, positioning the fuel load well aft of the craft’s centre-of-gravity will impart a slight nose-up tendency when the craft is travelling at low speeds, which will help it to rise up onto its planing surfaces as it accelerates at the start of each run.

     To protect the cell from the heat generated by the close proximity of the engine’s jet-pipe (it passes over the top of the cell, just inches away), a thermal protection shroud is to be added.

     Because the cell is of a flexible construction, it cannot maintain its shape when filled with fuel. It is therefore contained within a tight-fitting compartment in the hull of the boat, spreading the fuel load more evenly. The compartment is situated at the rear of Quicksilver’s main hull module and its rear wall and side walls will be formed by the craft’s inner skin. The cell rests upon (and is normally permanently attached to) a lightweight aluminium supporting pallet which clamps into this compartment and is removable when necessary. This pallet comprises of an aluminium-honeycomb sandwich panel bonded to a flat supporting frame fabricated from square-section aluminium tubing.

     The tubular frame creates 50mm of vertical clearance between the bottom of the aluminium-honeycomb supporting floor and the craft’s inner skin, allowing space through which the fuel-line can pass on its route from the fuel pump, which is semi-recessed in the floor, to the engine. The wire which supplies electricity to power the fuel pump also passes through this underfloor space.

     Advanced Fuel Systems designed and manufactured the aluminium fuel cell pallet, too, and will also supply further components in due course to complete the fuel system installation.

     Provision is being made for an additional fuel cell to be fitted, if and when it is required, within the main hull module. Sited directly above the existing fuel cell, in a space atop the jet-pipe, this back-up cell – known as the “saddle tank” – will gravity-feed fuel to the primary cell. Also purpose-made for Quicksilver, it will increase the total fuel capacity of the boat to 400 litres. The additional fuel reserves may be required during extended developmental running.

This is the fuel pumpIt took some finding! Here’s the story …

Back in the days when Quicksilver’s engine was installed in a Buccaneer bomber aircraft, fuel was delivered to it by a piece of equipment known as a proportioner. This device was, however, completely unsuitable for use once the engine was transplanted into the boat. The reason is that Quicksilver only requires a relatively small amount of fuel for a run, and therefore only needs to draw fuel from a single source. Whereas the Buccaneer, which was designed to undertake much longer journeys, had four fuel tanks for each of its two engines – hence the need for proportioners, which drew fuel simultaneously, but at different rates, from all four tanks, so as to maintain the aircraft’s centre-of-gravity within safe limits as fuel was consumed during flight.

     With Quicksilver having but a single fuel source, and the Buccaneer-era proportioner being relegated to a corner of the workshop because it represented superfluous weight and complexity, the way ahead seemed straightforward. One fuel pump was all that was required! But high-performance engineering is seldom that simple, and it proved to be an extremely difficult challenge to actually find a fuel pump capable of matching Quicksilver’s demanding requirements. There were several aspects to the challenge. First of all, the pump had to be able to deliver kerosene at the one-litre-per-second supply rate required when the craft’s Rolls-Royce Spey engine is running at full throttle – and that’s an extremely swift rate for just one relatively lightweight and compact pump. Secondly, the pump had to be able to run on a 24-volt electricity supply, rather than the three-phase supply that pumps of this class typically operate on (in order to save weight, we had removed the three-phase electrical generator from Quicksilver’s engine, along with the hydraulic pump and the constant-speed generator).

     The search proved difficult and time-consuming. Eventually, however, the hunt – which involved several members of the team – yielded fruit. A batch of ex-surplus military fuel pumps that had lain untouched since the mid-1960s was discovered just before they were due to be melted down for recycling. Any one of these pumps could do the job. The rest could be retained as spares.

     Our selected pump is an aircraft-type fuel booster pump manufactured by the SPE Company Ltd. of Slough, Buckinghamshire, in the early 1960s. It is believed that this particular pump may be of the type that was fitted to the FAW.1 version of the de Havilland Sea Vixen interceptor aircraft, dozens of which served with the Fleet Air Arm of the Royal Navy. The Sea Vixen FAW.1 began to be withdrawn from service in 1966, and the fuel pump installed in Quicksilver was almost certainly never fitted in an aircraft, as it is in factory-fresh condition.

     A Ministry of Defence identification tag removed from the pump prior to its installation in Quicksilver’s fuel cell indicates that it was certified “As New” on the 8th March 1966, following a successful component test at the Royal Naval Aircraft Yard, Belfast. Certainly, it could not have been immersed in fuel after that date, because the signatured ID tag is made of cardboard and it is in pristine condition.

     So, locked away for safekeeping, the Quicksilver team has several spare fuel pumps identical to the one currently installed in the boat, all apparently unused.

Safety first …
second … every time

En route to the engine, the fuel passes through an emergency shut-off valve. The shut-off valve would only be used in exceptional circumstances, either to prevent a leak in the fuel-line causing spilt fuel to accumulate in the boat and pose a fire hazard, or to prevent an on-board fire being fed by fuel, or to shut off the flow of fuel to the engine as part of an emergency procedure to slow the boat down if the throttle system for any reason malfunctions.

     Oliver Valves, a sponsor of the Quicksilver project, has developed the fuel shut-off valve specifically for the craft. The valve is operated by a wholly-independent pneumatic system. The picture above shows the valve being pressure-tested with compressed air at Oliver’s Knutsford, Cheshire facility late last year. Seen at left, explaining the test procedure, is Oliver Valves’ Works Engineering Manager, Nick Howard. The design of the valve was led by Paul Shillito, Engineering Director of Oliver Valvetek.

     The normal method for shutting down the engine is, of course, by use of the throttle. However, the emergency shut-off valve has been incorporated as a further tier of safety, in keeping with the Quicksilver project’s underlying philosophy: ”Safety First”. The shut-off valve would only be used as a last resort, as abrupt fuel starvation would cause cavitation in the engine’s own internal fuel pump and may thereby damage it.

     Oliver Valves celebrated its 30th anniversary in 2009 by signing a contract to support the Quicksilver project. Europe’s largest small-bore valve manufacturer, Oliver Valves is one of Britain’s fastest-growing engineering companies, with annual sales exceeding £50 million. It supplies principally to the process-plant, power generation/distribution, offshore and sub-sea industries.

     Pre-delivery testing of Quicksilver’s emergency fuel shut-off valve was rigorous. The valve must be capable of operating in every conceivable failure mode, including total incapacitation of the driver and total failure of the 24-volt electrical system. It represents an advance on emergency shut-off systems for previous speed-record applications, so its development presented a demanding series of challenges and the test regime had to be correspondingly thorough.

     Tests included cycling the valve actuator under pressurisation conditions to ensure that the boat’s movements on the water will not cause a sudden loss of pressure in the actuator.