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of Bloodhound are to be made in composite, under the eye of F1 and LMP composite designer, Stuart Allen. UMECO ACG, bettter known as Advanced Composites Group, is manufacturing the nose, monocoque, jet engine intake and wheel fairings. Painter: ‘In terms of composite manufacturing, the target of having a rolling chassis ready by the end of 2012 dictates that the main structures, including the monocoque, need to be bolted together around September.’


ENGINES Dr Davis is now ‘embedded’ at Cosworth, working on the rocket control system that, as well as driving the HTP (high test peroxide, the rocket oxidiser) pump, also supplies hydraulic pressure for the air brakes and


the HTP control valves. ‘Cosworth have given great support,’ related Painter, who is responsible for, among other things, integration of the APU and the design of the gearbox that connects the engine to the HTP pump. This gearbox contains Xtrac gears running in a machined-from-billet casing currently being made with the assistance of Jaivel and Newburgh Engineering. It connects to the Cosworth engine via an AP Racing carbon clutch. The gearbox actually fulfils five roles: it reduces rotational speed from the engine’s 18,000rpm to 11,000rpm for the HTP pump; it provides a means of starting the APU via an ARK Racing starter and ring gear; it provides hydraulic power; it has a dog clutch to engage with the APU pump; and it enables the clutch to de-couple the gearbox from the APU if required. All of this work is tied into


the next series of rocket engine tests. In August 2011, a 6in (152mm) version of the Falcon hybrid rocket was successfully fired, but now a sequence of validation tests are planned in


which the full size 18in (457mm) rocket will be run using the APU, gearbox and pump, the HTP tank and its nitrogen pressurisation system. In other words, most of the rocket system that will run on the finished vehicle.


INTEGRATION One of the main challenges has been with packaging, as Painter expanded: ‘There were quite a few elements to take into account with the Cosworth APU alone. For example, we have to meter the air to the inlet because, at higher Mach numbers, there is considerable ram effect. Also the stagnation temperature can be 130- 140degC at the intake, which no race engine is going to like! The location of the APU exhaust was critical too for, as speed goes through the transonic region, shock waves move along the fuselage so we had to ensure the APU’s exhaust didn’t emerge where there are high-pressure areas. It now locates in a low- pressure region under the car. And then there’s the need to access the APU, especially at the start of a day’s running and during the mandatory one-hour maximum turnarounds between record attempt runs. These are things we have to think


through now to ensure good serviceability.’ Recent aerodynamic


developments posed some potential challenges to the vehicle’s layout, too. A Design of Experiment programme fixed the rear lift problem that became apparent following the switch around of the jet and rocket engines, but there was still the unacceptable yaw stability problem to deal with. With the major masses unable to move significantly in order to move the c of g forwards, the only other option was to move the lateral centre of pressure rearwards, which was achieved by increasing the tail fin size (but not its width). Interestingly, this actually had the additional benefit of reducing drag. Work is also ongoing on the suspension systems and the jet fuel tank. Painter is working with Jonathan Tubb at Advanced Fuel Systems on the details. Project director Richard Noble


also reported in his August 2011 online diary that the design team was working on weight saving because the car had become heavier than planned. With the proposed venue for the record attempt, Hakskeen Pan, offering just a 12-mile (19km) track length, time will tell if this weight gain can be cut or indeed whether it is critical to the mission.


TECH SPEC


Bloodhound SSC (www.bloodhoundssc.com)


Length: 44ft (13.4m) Weight: 6422kg (14,158lb) fuelled


Chassis: steel spaceframe and carbon composite


Engines: Rolls Royce EJ200 jet engine; Falcon Project hybrid rocket motor; Cosworth CA2010 F1 engine


Thrust: 47,543lb (212kN) combined


Wheels: 900mm, aluminium, v-section


Braking: air brakes (800mph); twin parachutes (600mph); friction brakes (200mph)


January 2012 • www.racecar-engineering.com 23


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