Faster than a speeding
bullet...
In 2014 a small team from the UK will dispatch a car to Africa with the aim of it speeding across
the desert at 1000 mph. We find out how chemistry powers the car to success.
flow images
Josh Howgego
14 | Education in Chemistry | May 2012
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In short
the bloodhound project
In an unassuming, square brick
warehouse, a team are building a car
which will travel at 1000 miles per
hour. Called Bloodhound, this
13 metre long machine is the
brainchild of Richard Noble, a man
who knows what it’s like to be the
world’s fastest man, having driven
Thrust 2 at a speed of 633 mph (not
quite the speed of sound) in 1983. But
it seems that it’s not (just) a desire for
insane speed that drives him.
●● In a bid to break the
world land speed
record, the Bloodhound
project aims to inspire
more young people to
study science
●● Bloodhound is
powered to 1000 mph
by an HTP fuelled
rocket
Reengineering our lives
Noble’s goal with the Bloodhound
project is to inspire a new generation
of scientists and engineers. He was
inspired by the Apollo effect – during
the space race of the 1960s the
excitement hugely increased the
number of young people wanting to
study science. ‘You can’t excite people
with electric cars and wind turbines’
says Noble. A 1000 mph car might
just do it though.
There is also a serious side to the
mission. ‘What is the single biggest
threat facing us today?’ Noble asks in
a recent video on the project’s online
TV channel (http://bit.ly/z2Ffde).
In short, Noble thinks challenges like
cutting emissions and supplying food
to a growing population demand
bold ideas from scientists and
engineers – and at the moment there
aren’t enough of them to try.
Bloodhound is a daring and
imaginative project from whatever
angle you care to come at it. This is
the mother of all research projects;
there are lots of scientific problems
the team need to solve.
Daniel Jubb,
rocket engineer
(has a moustache
most men would
kill for and a job
title to match)
demonstrates to
eager onlookers
which prompted the team to choose
the softer desert surface of the
Hakskeen Pan in South Africa. This is
essentially hard-baked mud, and will
allow the wheels some lateral grip.
The final choice for the wheel
material was aluminium. Aluminium
is extremely light (2.7 g cm-3) and
strong, but slightly softer than rival
material titanium, which is
prohibitively expensive.
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Power
Another interesting challenge the
team faced was how to power the car.
In the end they have opted for two
Sections of Bloodhound’s shell are
power sources; a Eurofighter
made from different materials,
Typhoon jet engine, which will
carefully designed to fulfil different
roles. The most important part is the power the car up to a speed of about
350 mph, and then a rocket – the
carbon fibre shell that forms
largest ever built in the UK.
Bloodhound’s nose and protects
The project’s rocket engineer is
the pilot.
Daniel Jubb. Despite Bloodhound’s
Carbon fibres are made from thin
educational overtones he is not the
sheets of graphite woven into a
most traditional advert for school –
strong polymer to create a filament.
They are extremely strong (see table) he left at 13 to be home schooled and
start a rocket engineering firm with
in tension along their axes (because
his grandfather.
of the strong carbon-carbon bonds)
Like many boys the young Jubb
but, the layers of graphite – like those
in a pencil – are only held together by had a passion for pyrotechnics, but
– rather exceptionally – he had
managed to launch over 100 rockets
Density
Tensile strength
Young’s
by the age of 10. ‘My grandfather and
–3
g cm
MPa
modulus
I would drive out to the test site with
2.7
280
0.1
several different [rocket]
configurations that we’d come up
7.8
400
0.05
with ready to go,’ Jubb tells me, ‘we’d
4.6
950
0.21
fly several of them to try and get
1.6
2000
0.91
some performance data points. The
The body
Wheels
At 1000 mph Bloodhound’s wheels
will spin at about 170 times a second,
and generate a stress of about 50k
times the force of gravity (g) at the
rim. Although some older land speed
cars have used inflated tyres, for
Bloodhound the stresses involved
mean only a solid wheel can cope.
However, a solid wheel largely
determines the surface the car will
run on. Land speed records are often
attempted on salt pans, which are
very flat and very hard. This gives
good grip but little friction, and is
ideal for high speeds. Since
Bloodhound will use solid wheels, a
salt pan could be dangerous. With no
give in the wheels at all, any tiny
irregularities in the surface could
cause a big bump. It was this factor
weak intermolecular forces. The
strength of the material is therefore
highly anisotropic – that is, not the
same in all directions. The challenge
for the engineering team is to work
out how to weave carbon fibres into
composites so that the directional
strength of the carbon-carbon bonds
is best exploited.
Material
Aluminium
Steel
Titanium alloy
Carbon fibre
May 2012 | Education in Chemistry | 15
Land speed record timeline
1983 Richard Noble pilots
Thrust 2 to a speed of 633 mph.
1997 Thrust Super Sonic Car (SSC),
piloted by Wing Commander
Andy Green is the first car to break
the sound barrier, racking up a
nimble 763 mph.
2000 (Exact date not disclosed).
Americans begin work on a rival
landspeed record attempt project;
the North American Eagle which
aims to reach a speed of 808 mph
and wrestle the title from the
British. Spookily, the NASAstarfighter from which the craft is
built has the tail number 763,
which is the current land speed
record in mph!
2007 American adventurer Steve
Fossett disappears whilst in the
final stages of preparing an
assault on the record with his car
Sonic Arrow. The car is currently
way we had more fun was to build a
faster and better rocket and the way
we got there was to use a scientific
approach.’
The chemistry of rockets
Jubb and the Bloodhound project had
to consider several different options
before eventually achieving the right
balance for the car’s rocket. There
were some quite exacting
requirements; it had to be quite
short burning, but reach
maximum thrust (for
maximum acceleration) as
quickly as possible. An ‘off
switch’ was essential
because the pilot, Wing
Commander Andy
Green, places great
16 | Education in Chemistry | May 2012
up for sale and there are rumours
of an unknown buyer. Fossett is
believed to have been killed in a
plane crash.
October 2008 The Bloodhound
project gets the go ahead from
science minister Lord Drayson
who says ‘there is every possibility
that the Bloodhound team will
reach the absolute speed limit for
a car on wheels.’
value on being able to stop the car if
anything goes wrong. And, of course,
it had to be as safe as possible.
A rocket is essentially a
combustion reaction in a tube, so it
requires three things: heat, oxygen
and a fuel. A rocket is an enclosed
space, so it must use an oxidant – in
this case a compound that reacts to
give off O2 – to provide the gas
consistently during the firing.
oxidiser) and liquid hydrogen (the
fuel). Bloodhound chose a different
route – a hybrid rocket, using solid
fuel rods made from a synthetic
rubber and a liquid oxidant.
‘Initially we thought that nitrous
oxide [(N2O) or laughing gas] might
be the way to go for the oxidant’
explains Jubb. ‘We also considered
nitrous acid (HNO2) and looked at
the classic combination of kerosene
and liquid oxygen. But eventually we
decided upon HTP.’
HTP (High Test Peroxide) is an
86% solution of hydrogen peroxide
(H2O2) in water, and Bloodhound will
carry 963 kg of the stuff. HTP gives
off oxygen in the following
decomposition reaction:
H2O2 → H2O + O2 + heat
Because the reaction is so
exothermic, the water produced is
immediately converted into steam
which expands quickly and is forced
through an aperture, producing
thrust. Initially the HTP is just
allowed to trickle over a silver bead
catalyst pack, which helps initiate the
decomposition reaction. In phase
Fuel
two, the flow of HTP is increased.
The first decision to be made
was about the physical state of To generate the level of power that
Bloodhound needs (about 122 kN
the fuel and oxidiser. Most
of thrust), it must be very fast, so
rockets use liquid fuels.
engineers have installed an engine
The space shuttle
from a Formula 1 car to pump it
rockets, for example,
used liquid oxygen (the across the catalyst pack. This raises
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the bloodhound project
the temperature to 600oC which is
enough to ignite the rocket. This
technique keeps Andy Green happy
because, if he does feel the need to
abort the run, he can switch off the
HTP pump and the rocket will
quickly run out of oxidiser.
Spontaneous reaction
The strength of H2O2 as a fuel is also
its downside: the decomposition is so
favourable that H2O2 is dangerous.
The reaction is entropically favoured
(ΔS = 70 J mol–1 K–1) and
enthalpically favoured
The desert surface
of the Hakskeen
Pan, South Africa
where Bloodhound
will reach speeds of
over 1000 mph
(ΔH= –98 kJ mol–1) as the bonds
formed release more energy than is
required to break the H2O2 bonds.
Consequently, the reaction is
thermodynamically spontaneous – it
takes almost nothing to get it going.
That means the aluminium tanks
which store the HTP have to be
‘passified’ to remove any nucleation
points which could set the HTP
going (‘chromium ions from stainless
steel components are a particular
worry’ says Jubb). The passification
involves a rigorous regime of
ultrasonic cleaning, immersion in
The speed of sound
christopher parypa/shutterstock.com
Intriguingly the speed of sound is dependent on
air temperature. Sound is essentially vibrational
waves in matter (in this case the air). If the air is
cooler it has less energy and the particles (oxygen
and nitrogen molecules mostly) move less
quickly. This means at cooler temperatures sound
travels more slowly through the air. (See also
http://bit.ly/xuEgKM).
This is why land speed record teams sneakily
try their runs early in the morning when the air is
cool. The lower the temperature the better: at
15°C the speed of sound is 761.2 mph. At 25°C it’s
a little higher: 768 mph. Although of course this
doesn’t change the absolute speed of the car, it
does alter the Mach number (M), which is defined
for a given temperature as:
M = actual speed / speed of sound
concentrated nitric acid and then
careful testing with increasing
concentrations of H2O2.
Chemistry is central to the rocket
powering Bloodhound, but Jubb has
called on other areas of science to
fully understand how the rocket
works, such as the dynamics of the
superheated gases. The project team
had to understand the kinetics of the
reaction to work out how fast the
rocket will burn. They designed an
entirely new computer program to
simulate this, which could prove
useful for rocket design in other
applications.
The legacy will be ...?
Bloodhound’s influence could reach
far beyond itself, into education,
engineering and through the
scientists it inspires, to all the
unimaginable inventions and
innovations they will create.
Bloodhound aims to break the
800 mph record in 2013 and reach
1000 mph in 2014, but for the long
lasting benefits of the project, we
may have to wait a little longer.
Josh Howgego is a chemistry PhD student
and writer based in Bristol.
Further reading
●● The Bloodhound project
http://www.bloodhoundssc.com
●● Bloodhound education, including free resources for
schools http://bit.ly/bldeduc
●● Development of the Bloodhound hybrid rocket
http://bit.ly/bldhybrkt
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May 2012 | Education in Chemistry | 17
the bloodhound project
The Bloodhound Team
Teaching catalysis
Why not use the Bloodhound story as an
introduction to teaching catalysis? As the
article describes, the car uses the catalytic
decomposition of H2O2 as an important
source of thrust.
This classroom experiment gives a very
visual demonstration of the relative
properties of some potential catalysts for
decomposing H2O2. Several measuring
cylinders are set up each containing a
little washing up liquid and a small
amount of a catalyst.
Free resources for schools
Hydrogen peroxide is poured into the
cylinders and a foam rises up the
cylinders at a rate that depends on the
effectiveness of the catalyst.
Download the instructions from Learn
Chemistry at http://bit.ly/H2O2demo,
or watch the demonstration at
http://youtu.be/Ta4DomSDzF8
This demonstration is also available as
a guided investigation for students. A
worksheet and teacher notes are available
at http://bit.ly/H2O2invest.
The vision for the
Bloodhound project is to
inspire a new generation
of students to become
scientists and engineers.
To help achieve this aim,
the project is supported
by a website full of free
information and resources.
You can register for the
Bloodhound Education
Programme and become involved
with the project by filling in your
details here: http://bit.ly/bldeduc
This will give you access to a huge range of teaching
materials and full open access to the design, build, test and
record breaking attempts of Bloodhound.
More information
There is much more on the Bloodhound website which will be
of interest and help to engage students with science and
engineering:
●● Careers information – http://bit.ly/bloodhoundcareers
●● Facts about the car – http://bit.ly/bloodhoundcarfacts
●● Video interviews with the design team –
http://bit.ly/bloodhoundinterviews
●● Projects you can be involved with –
http://bit.ly/bloodhoundopportunities
●● Events showcasing Bloodhound and its technologies
– http://bit.ly/bloodhoundevents
18 | Education in Chemistry | May 2012
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