Report

The Bloodhound SSC Land Speed Record Challenge – An Independent Appraisal © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice. Main drives What is sought : • Achieve and possibly break the 1000 MPH speed mark for a land vehicle. • Stimulate the interest for mathematical and physical subjects (STEM). – Science – Technology – Engineering – Mathematics • Encourage young people into engineering. • Generate an iconic project based upon extreme research and technologies, stretch the state-of-the-art envelope and spread the knowledge as widely as possible. • Allow the general student population, throughout the world, to participate in an open-access scheme. • Generate a substantial and lasting exposure for the project's sponsors. 2 © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice. A brief description for a great design How to fulfill these goals: • 1000 MPH equals 1.314 the speed of sound or 447 meters per second. • Approximately 100 thousand horsepower are required to overcome air drag. • The combined action of an advanced jet fighter engine and a hybrid rocket may provide this enormous power. 3 © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice. The Bloodhound SSC team Who is doing the job?: The complete multidisciplinary team is made up of 49 persons directly in charge of materials, mechanics, aerodynamics, combustibles, integration, stability, control systems, communication systems, assembly, logistics and so on. 4 © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice. Land Speed Record Evolution A source of fascination LSR [MPH] 800 1898: 39.240 MPH Jeantaud, electric, Gaston de Chasseloup, France. 1997: 763.002 MPH Thrust SSC, turbofan Andy Green, UK. Green Line: Speed of sound, 761.222 MPH @ 15 °C. The large step in 1965 belies an important technological change: usage of jet engines for thrust. 5 700 600 500 400 300 200 100 0 1890 1900 1910 1920 1930 1940 © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice. 1950 1960 1970 1980 1990 2000 The sound barrier Speed of sound is temperature-dependent: cAIR RAIR T 1.4 Air isentropic constant (diatomic) RAIR R 8.314472 287.057329 MM AIR 0.0289645 At rest Subsonic Gas constant for air T 288 .15 Thermodynamic temperature Therefore: c AIR 1.4 287.057329 288.15 340.297 m 1 225.068km s h 761.222MPH 6 Transonic © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice. Supersonic The rationale behind the name Why Bloodhound ? Bristol Bloodhound • British designed surfaceair missile with an 85 km range. • Capable of achieving 2.7 times the speed of sound. • Thrust provided by two ramjets and four solid fuel rockets. • Accelerates to the speed of sound in a mere 2.5 seconds. • In service from 1958 until 1991. • First design by Mr. Ron Ayers, now in charge of the Bloodhound SSC aerodynamical development. 7 © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice. The official test profile A typical sequence Within two minutes the Bloodhound SSC: • Accelerates from standstill, up to 1000 MPH and back to rest. • Traverses clocked mile in 3.6 seconds. • Acceleration subjects pilot to twice the force of gravity. • Deceleration force is 3.5 × g. • Distance travelled is almost 12 miles. • Fuel consumption is almost 250 kg; propellants expenditure is 1144 kg. • One hour allowed for turn-around to attempt return run. blue: speed 8 red: acceleration © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice. green: clocked mile The location Where it may be driven at 1000 MPH • Hakskeen Pan, at the NW corner of South Africa, close to the Namibian border, at a 794 meter altitude. • A extremely flat and wide stretch of desert with a very hard, compact surface. 9 © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice. Some issues to think about Are they serious about 1000 MPH? • The speed record for low flying aircraft amounts to 988 MPH. Not even the Lockheed Starfighter F-104, one of the best-ever advanced fighter jets, has done it to 1000 MPH at low altitude. • From 763.002 to 1000 MPH there is a 31% step, an extremely difficult feat where gains usually come very slowly and painfully in exchange for enormous investments. • Some other stuff they must watch out for: – Keep the car from taking-off like an airplane – Ensure it follows a straight path – Keep it from breaking into pieces. Air acts like a solid wall at 1000 MPH. 10 © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice. Main technical specifications Size length = 12.86 m; width = 1.90 m; height = 3.00 (at vert. stabilizer) Mass empty = 4 738 kg; ready-to-run configuration = 6 422 kg Jet engine Eurojet EJ-200, low-bypass turbofan w/ afterburner; 90 kN static thrust Hybrid rocket Falcon HTP / HTPB, 111 kN average thrust Aux. power unit Cosworth CA 2010 V8, 800 BHP @ 18 000 RPM Braking two air-braking flaps, two parachutes, hydraulic friction pads Control 3 Intel Atom processor controled via Diamond systems Neptune Programming Mathworks Simulink Communications Intel WiMAX via Diamond systems Pluto, Windows CE-based 11 © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice. The wheels No rubber tire will take such monumental stress • Built out of solid aluminum, at 149 kg each. • At 1050 MPH their rotational speed exceeds 10000 RPM. • For these conditions, the centrifugal force is • • 12 around 51000 times stronger than gravity. Computer-based finite-element software was tapped for their design. Equipped with peripheral grooves which "bite" into the terrain to aid steering over a straight path. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice. Eurojet EJ-200 low-bypass turbofan Same type that powers Eurofighter Typhoon • Static thrust = 60 kN, dry; 90 kN, w/ afterburner (sea-level, 15 °C). • Mass flow = 76 kg / s (1.225 kg / m3 air density at sea-level). • Volumetric flow = 62 m3 / s (can displace all air in mid-size room in 0.62 s). • Fuel consumption = 0.25 kg / s, idle; 4.32 kg / s, full afterburner. • Total fuel expenditure = 250 kg (for 60 second working cycle). 13 © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice. Falcon HTP / HTPB hybrid rocket Especifically designed for this job • 111 kN average thrust. • Equivalent power output = 77 500 HP. • Burn time = 20.1 s. • HTPB Hydroxyl-terminated polybutadiene (rubber), fuel = 181 kg. • HTP High-test peroxide, (H2O2) oxidizer = 963 kg. • Total propellant mass = 1144 kg. • Total impulse = 2230 kN×s. 14 © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice. HTP Cosworth CA2010 V8 auxiliary power unit Same engine as used for Williams F-1 racing • 800 BHP @ 18 000 RPM. • Drives the HTP oxidizer pump at 7.58 MPa pressure with 47.6 kg / s mass flow rate. • Powers the 24-volt generator for the vehicle's electrical system. • Delivers hydraulic pressure for air-brakes and friction brakes. 15 © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice. Aerodynamical characteristics u [m / s] CD A [m2] 0.5 170.148 1.10 0.7 230.208 1.13 1.0 340.297 1.28 1.4 476.415 1.32 Power fit 1.4 CdA [#] NM [#] 1.3 1.2 Real 1.1 POW 1.0 150 200 250 300 350 400 450 500 u [m/s] Air drag retarding force exerted over a body moving through a fluid is; (u is speed in m / s): 2 FD r CD A u 2 0.19555 CD A is speed-dependent drag area in m2; approximated by curve fitting: CD A 0.39867u r is air density in kg / m3, influenced by altitude and pressure; whereas p0 = 101 325 Pa is the reference atmospheric pressure: x is the altitude-dependent coefficient (standard atmosphere); z is altitude in meters; T is thermodynamic temperature in kelvin 16 © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice. r p0 x x 352.978272 RAIR T T x 1 2.252615105 z 5.263159 Air drag function FD 70.360918 x 2.19555 u T Aerodynamical drag force 200,000 150,000 Fd [N] Substitution of all factors into air-drag equation leads to the final expression for this retarding effect: x 352.978272 0.39867u 0.19555 u 2 T FD 2 As shown in graph, for speeds around 1000 MPH the drag force acting against the vehicle lies on the 17-ton range. This, together with the 447 m / s metric equivalence of speed yields a power requirement of 101 913 horsepower: PD FD u 170000 447 7.5997107 W 17 100,000 50,000 0 0 100 200 300 400 500 600 700 800 900 1000 1100 u [MPH] 0 m, 0°C © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice. 794 m, 30°C Total available thrust Taking into account the 90 kN static thrust FS0 provided by the EJ200 turbofan for standard sea-level conditions, as well as the fact that this unit is called upon to perform under non-standard, nonstatic conditions, the following expression applies to the net thrust: FN T0 T x FS 0 0 x m T 0 u T T Whereas T0 = 288.15 kelvin is the standard reference temperature and m T 0 = 76 kg / s is the reference mass flow rate at sea-level. If the appropiate numerical values are substituted, an equation for the net thrust, as provided by the EJ200, results: In addition, considering that the 111 kN average thrust from the Falcon hybrid rocket is not affected sensibly by the environmental conditions, a final expression for the total available thrust is found: FT 2.59335 10 7 18 x x 2.18994 10 4 u 111 10 3 T T © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice. FN 2.59335 10 7 x x 2.18994 10 4 u T T Maximum attainable speed FN Fd FR Frr The equilibrium conditions applicable to the maximum (constant) speed regime may be described by the following equation; FN FR FD Frr (the Frr rolling resistance component being neglected) By substituting the numerical expressions formerly derived, a higher-order algebraic equation (ordered in descending powers of the speed u) results: x 2.19555 4 x 70.360918 19 T u 2.18994 10 T u 2.59335 10 7 © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice. FT FD 0 x 111 10 3 0 T Solving with advanced scientific calculator Numerical coefficients and parameters programmed into memory registers: Altitude coefficient for pressure ratio. Exponent for pressure ratio. Average rocket thrust. Thermodynamic temperature. May be modified. Independent term coefficient. First-order term coefficient Pressure ratio determined by values in P and Q. Higher-order term exponent. Higher-order term coefficient. 20 © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice. The numerical power of a HP35s Next, according to the stored values, the equation editor is used to input the expression: Z X Y X X U W U V R0 T T T Higher-order term First-order term Independent term Rocket thrust Finally, upon invoking the equation solver and following the prompts, the solution arises: Multiplying the displayed solution (given in m / s) to get km / h and converting to MPH: u 473.31374m 1 058.7727MPH s 21 This particular solution applies to a 794 meter altitude and a 30 °C (303.15 K) ambient temperature. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice. Final assessment for the Bloodhound SSC Repeating the process for assorted altitude and temperature values, the following table and graph may be built from the resulting data set: z=0m x = 1.00000 z = 794 m x = 0.90938 Maximum theoretical speed for Bloodhound SSC T [°C] u [MPH] T [°C] u [MPH] 0 1000.8 0 1027.4 5 1005.7 5 1032.7 10 1010.7 10 1038.0 15 1015.6 15 1043.2 20 1020.4 20 1048.4 1,020 25 1025.3 25 1053.6 1,000 30 1030.1 30 1058.8 980 35 1034.9 35 1063.9 40 1040.0 40 1069.0 1,100 u [MPH] 1,080 1,060 1,040 0 5 10 15 T [°C] 0m 22 20 © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice. 794 m 25 30 35 40 Thank you © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.