The Bloodhound SSC Land Speed Record Challenge

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.
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© 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.
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© 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.
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© 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.
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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
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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 surfaceair
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.
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© 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.
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© 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.
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© 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
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© 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
•
•
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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).
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© 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.
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© 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.
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© 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
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© 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  2.252615105 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  7.5997107 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.
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© 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
R0
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
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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.

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