The Three Rocketeers

Deep in the Oxfordshire countryside,

a group of British rocket scientists are making the final checks

before testing an experimental rocket engine.

Consol armed.

Defying all conventional wisdom,

one man has pursued a dream his entire working life.

Lead engineer Alan Bond believes he is now on the threshold

of realising his dream - to build a revolutionary spacecraft

that achieves Earth orbit in a single leap.

Three, two, one...

Into sequence.

If their calculations are correct,

their revolutionary design will herald by new era in space flight.

WHIRRING

This is the story of how a small and talented group

of British engineers overcame personal adversity,

shrugged off government intransigence

and defeated the Official Secrets Act to pursue a dream.

A dream that began in a boy's back garden shed.

ROCK MUSIC PLAYS

It's traditional in Britain that all things start in a shed.

And we've kept up a long tradition on that.

Alan Bond's passion for space travel began at an early age.

The background really starts back in the 1960s.

Going back to my childhood days, I sort of looked at Dan Dare and saw

that Dan Dare was not constrained to messing about on planet Earth,

he had a whole solar system at his disposal.

Since those days,

I've always felt that the human race has got much more ahead of it

than just being confined to the surface of one little messy planet.

As a teenager, I began to build my own rockets and really got to grips

with what the problems were of getting into space.

It very quickly became apparent that rockets were very limited

in what they can actually do.

And from a very, very early stage,

I realised that we weren't going to get Dan Dare

out of the existing sort of rockets, we've got to have something better.

-RUMBLING

-This is a new sound.

The sound of a space age.

The sound of the Blue Streak rocket.

Nonetheless, the possibility existed for a long time throughout the 1960s

that if we could just make the rocket engine a little bit better,

a little bit more efficient, we might be able to come up with

an overall vehicle

which did not have to throw chunks of it away to go into orbit.

The idea was out there that we could and should do better.

As it happened, we didn't get very far with that.

All around the world, many people realised that rockets

in the form that we'd got them were just not going to deliver

in the long term the kind of transport technology

we were looking for.

So virtually every space company in the world was trying to do better.

This is where a rather fortuitous sequence of events occurred.

Back in the very early '80s,

we had a meeting that was organised by the French.

The French wanted to come over and tell us their plans for Ariane 5.

They had plans to put a winged mini shuttle on top of it called Hermes.

Alan and I, who'd known one another for a long time,

sat at the back of this meeting

and we said, "This is Dinosaur reinvented,

"the 1950s United States Air Force thing.

"There must be a better way of entry in the 21st century

"than going with this antique technology."

In round about 1984,

I had a meeting with Bob Parkinson

and John Scott-Scott from Rolls-Royce in my office.

Well, the story was that Alan had been working on something quietly.

Nobody was quite sure what it was.

I'd always been interested in pushing propulsion much harder.

Whilst the solar system and trips to the moon represent a serious challenge,

I'd been interested right from my earliest days

in going much further than that

and that drew me into more advanced propulsion, nuclear propulsion.

One of the things that came out of those studies is that

if you have a hot nuclear reactor on a rocket

and you have cold liquid hydrogen,

I realised that you could replace the nuclear reactor with hot air at roundabout Mach 5.

And that opened up the prospect of a whole new range of engines

that no-one had considered before.

But then one day he turned up at our house, literally, at home...

And he said, "I want to talk to you

"about a possible new propulsion system

"that could actually sort of completely revolutionise rocketry as we know it."

Alan's visionary thinking had come at the right time.

The world was growing tired of the ever-mounting cost of reaching space.

The world was beginning to suffer

from the cost of launching satellites more and more,

because more and more people wanted to put up small clusters,

communication things, land resources.

All the usual things, which at the moment, and still to this day,

are being launched by totally expendable rockets.

Nothing comes back except bits of wreckage.

To reach orbit, conventional rockets burn tons of hydrogen

and oxygen every second.

But when the fuel is spent, empty tanks and rockets

are simply jettisoned to burn up in the planet's atmosphere.

-MAN ON RADIO:

-Booster officer, confirm staging a good solid rocket booster separation.

Shut down. Sierra-D's have shut down. BDM fire.

What took thousands of man hours to make

has a working life measured in seconds.

So, people wanted cheaper launching things

and the only way to make it really cheap

is to make it like an airliner.

So I tinkered together the blue book and passed it to John

to find out what his interest was going to be on it.

It's pages and pages of theory and numbers. We turn to the back.

Here we are, paragraph seven, conclusion.

"The report has outlined a proposal for an air-breathing engine

"which may allow a single-stage-to-orbit

"space transportation system to be realised."

Now, normally if you talk to people about that sort of concept,

they will tell you it can't be done.

I examined all the rocket propellants that were available, including some you wouldn't like to work with.

And you just cannot hack it with rockets.

So you've got to make use of the atmosphere,

same as any other aircraft does.

Alan turned to his old friend Bob Parkinson for help.

Alan rang me up to ask me a question about propellant chemistry

and in the discussion over the phone, we said,

"It sounds like we've been working on parallel lines.

"We ought to have a meeting together."

Bob was thinking more about the actual vehicle side of things

and I was thinking more of the propulsion side of things.

The great thing about Bob is that he'd moved to British Aerospace

and he also, because of his very innovative character,

had the ear of the senior management.

As a consequence, he was able to get the project into British Aerospace.

And out of that came the HOTOL project.

The basic idea was simple enough.

Conventional rockets burn a mixture of liquid oxygen and hydrogen.

Hydrogen is an ideal fuel - it's light

and generates huge amounts of thrust.

In comparison, the oxygen it needs to burn is bulky and very heavy.

But Alan Bond thought he saw a way to cut HOTOL's need to store that oxygen on board.

It was obvious the atmosphere has to play a part in getting us into space.

Bond's breakthrough was the idea that HOTOL could steal oxygen

from the atmosphere.

And the whole idea of this was single-stage-to-orbit.

That was the key bottom line.

Now, to do it, if you look at the amount of work you've got to do

to get into orbit, it says use as much oxygen as you can

from any source except what's on the vehicle.

And so you drive yourself into the area of,

"How far can we go as an air-breathing machine?"

And therefore you lean heavily on gas turbine technology,

which is well-established,

and only use rocket technology when, putting it simply,

you've run out of air.

Together, the three engineers secured funding from the UK government,

British Aerospace and Rolls-Royce.

In those first heady days,

Alan's dream looked as though it was becoming a reality.

Bond's theory worked fine on paper,

but experiments in the lab soon brought disappointment and delay.

There were several problems with HOTOL.

One was the actual design of the aeroplane itself,

which was a magnificent attempt.

The other was the engine. There were issues over the engine.

To reach orbit from sea level,

HOTOL's engines would have to work flawlessly at extreme temperatures.

The air comes in at 1,000 degrees Centigrade as it slows down

and you can't put that through a compressor,

in fact, it's very difficult

to design the airframe to stand it for very long.

The key Alan came up with was to take that air coming in,

accept it in heat-resisting duct for the first little bit

and then cool it - drastically.

Alan's first choice

was to cool this thing right down

to just above the liquefaction point of the air which we breathe.

That's a long way down, but it could be done.

Bond's second breakthrough

was how he planned to cool the air entering HOTOL's rocket engines.

You've got hydrogen on board this vehicle,

which is a wonderful coolant.

By using HOTOL's liquid hydrogen fuel

to cool and compress the incoming air,

HOTOL only had to carry small amounts of oxygen

for when the vehicle reached space,

saving weight that could be used to carry cargo.

What we've got here is a typical experimental heat exchanger

from the HOTOL programme.

The liquid nitrogen went into these tubes at the end,

all the way through these fine tubes and out the other side.

The air flowed through there.

When we looked at the transit time

for air going through the heat exchanger or pre-cooler,

the answer comes out between one and two milliseconds.

That's a pretty short time for all this heat to be removed - bump!

The first experiments we did on rapid cooling

showed us that within literally 4-5 seconds,

the heat exchanger module would frost up solid -

no air flow through it at all.

It highlighted the key problem was not so much heat exchange,

which we believed we could do,

but how do we tackle the frosting problem?

Frost control wasn't the only problem the HOTOL team encountered.

Flaws in the airframe design soon became glaringly obvious.

Richard Varvill, a young aerospace engineer joining the team,

grappled with the spacecraft's aerodynamics.

We'd basically made a mistake right at square one,

which was to put the engines on the base of the fuselage.

You have to go back to the origins of the HOTOL project to understand how this problem came about,

we came from a background of vertical take-off rockets,

where, as you know, the engines are always on the base of the rocket

and it ascends vertically and you have the tankage above it.

On HOTOL, that seemed like a good starting point,

so we ended up with this long, slender hydrogen tank

sticking out ahead of the wings

because it gave a very structurally efficient configuration

for the airframe.

However, what we found was this very severe CGCP mismatch.

When fully fuelled, the weight of the hydrogen

balanced the weight of the engines at the rear of the craft.

But as the fuel was used up in flight,

the centre of gravity of the craft

shifted backwards towards the engines.

The centre of pressure, however, was forced forward,

leading to flight instability.

Or, as aerospace engineers call it, a CGCP mismatch.

To resolve this, we ended up making a lot of undesirable changes

to the aeroplane

and in the process, we lost, we reckon,

about four tonnes of potential payload.

'T-10, 9, 8, 7, 6, 5, 4...

'We've gone for main engine start. We have main engine start.'

From the outset, Britain had designed HOTOL

as a replacement for NASA's space shuttle.

'America's first space shuttle.

'And the shuttle has cleared the tower.'

Colombia had successfully launched a year earlier

with the specific goal of carrying payloads into space.

'We have main-engine start.'

'2, 1, booster ignition. And the final lift-off of Discovery.'

Whereas a space shuttle could carry 22 tonnes of cargo,

HOTOL's design capacity of 8 tonnes had now been reduced by half.

Unlike HOTOL, NASA's shuttle was a two-stage-to-orbit vehicle

with the vast majority of the rocket discarded

within minutes of take-off.

NASA described its space transportation system

as a kind of reusable space truck,

with each vehicle designed for a lifespan of 100 launches.

'3, 2, 1...'

In reality, in the 30 years the programme ran,

only a total of 135 flights were ever made.

But the shuttle remains

the only winged, manned and reusable spacecraft

to have successfully reached orbit and landed again.

'Main gear touchdown.'

'Nose gear touchdown.'

The shuttle programme may not have lived up to its original billing,

but it had the overriding merit that it actually worked.

With all its technical difficulties and its payload capacity halved,

the economic case for HOTOL was now on shaky ground.

We do need to have a look at greater commercial involvement

and consider really exactly what the strategy is

before we go into this highly expensive,

I think, not altogether well-directed space effort.

Despite Alan Bond's best efforts to persuade ministers

of the technical and commercial viability of his project,

they remained unconvinced.

The man in the street expects ministers

to evaluate these hugely expensive claims,

and until and unless these enthusiasts,

at home and abroad, satisfy us there's good value for money,

I think it's the duty of ministers to say,

"We admire your enthusiasm, but that bill is simply too much."

With all government funding for HOTOL now gone,

Alan's dream was in tatters.

As a last resort, he sought backing from Europe.

He intended to take his engine design

to the European Space Agency and continue his work there.

But once again, the government stood in his way.

Following meetings between Bob and myself

and some of the other people involved,

it was agreed that I would apply for a patent on the RB545 engine.

That immediately brought a classification.

That was a disaster to the HOTOL project.

It meant that we couldn't talk to the European Space Agency

and we were never able to disclose at the time to the European Space Agency

how this engine worked and what the advances in it were.

When the thing was classified "secret,"

it immediately brings it to "military use only."

That meant that I couldn't talk to anyone about it,

and even got leaned on not to talk to anyone in the UK about it,

including people at Rolls-Royce and British Aerospace.

I had to fight that, otherwise there would have been no project.

I was successful, but for the period up till 1993,

many years after the project had actually finished,

the engine remained classified.

In pursuit of his boyhood dream, Alan had started his career

working on Britain's first attempt to put a payload into space.

On 28th October 1971,

Black Arrow successfully placed into orbit Prospero,

an experimental satellite designed to test

the effects of space on communication satellites.

Ironically, the Black Arrow programme had already been cancelled

three months earlier by the government, on economic grounds.

To this day, Prospero remains the only British satellite

to have been launched by a British-built rocket.

For Alan, this was the start of a long and difficult relationship

with government funding for UK space projects.

That is a problem in Britain. Britain these days is not visionary.

There is a world out there.

The earth is a very, very tiny place in our universe,

and I think you need a certain amount of scientific knowledge

to appreciate that, and I think, by and large in Britain,

scientific knowledge is now rather a limited commodity.

Britain had closed the door on an active role in space vehicles,

and with it, independent access to space.

In America, however,

NASA was still pursuing the concept of a single-stage-to-orbit vehicle.

In 1986, as HOTOL was still underway,

President Reagan had announced

the United States' National Aerospace Program.

But rather than looking at

exotic and unproven engine designs like Alan Bond,

NASA wanted to build on the relative success of its Shuttle program.

It was firmly convinced that rockets were still capable

of propelling a spacecraft to orbit in a single stage.

Even as the United Kingdom was cancelling HOTOL in 1989,

in America, the government commissioned

a series of technology demonstrators for a single-stage-to-orbit vehicle.

Whilst in the UK, Alan struggled to find backers

for a successor to the HOTOL project,

in the US, Lockheed Martin was building the X-33 prototype.

The X-33 was never completed before it too was cancelled.

But in stark contrast to the position of the British government,

the United States continued to pursue its goal

of a reusable single-stage-to-orbit vehicle.

Back in the UK,

in frustration at the government's unwillingness to fund

or even permit a successor to the HOTOL project,

Alan and two of his colleagues,

Richard Varvill and John Scott-Scott, decided to go it alone.

They formed a new company, Reaction Engines, to continue development.

The fledgling company was based in Culham near Oxford,

on the same site as the Joint European Torus

where Alan had worked before transferring to the HOTOL project.

The Joint European Torus is a research reactor

designed to harness the power of nuclear fusion,

the same energy that powers the sun.

In such an environment, they rely heavily

on computer modelling techniques

to predict the behaviour of their experiments

before trying them out for real.

You could do an awful lot of modelling.

You'd think that the aerospace business was the place

that you'd learn that, but back in the 1970s,

computers weren't very available.

It took a long time to get onto a mainframe.

Also, the actual analytical techniques that were used

in the aerospace business at that time were very limited,

so you tended to make things and break them,

and make 'em and break 'em until they worked,

whereas the Atomic Energy Authority were building things

that, if you broke them, were actually quite dangerous,

so they had come up with a great deal more modelling

than the aerospace industry had.

I was fortunate that when I came to Culham to work on fusion,

I learned a lot about that, and I was able to apply that,

so given, suddenly, a PC of my own,

I found that I was already on my old Spectrum able to do an awful lot

that was still being carried out, say, in British Aerospace.

Using the techniques he had learned at JET,

Alan was able to continue working on HOTOL's legacy

without so much as a penny of government funding.

When we finished with the HOTOL project,

there were a number of outstanding issues.

The computer modelling, sort of using ideal conditions,

showed that there was tremendous actual potential behind the concept.

But what we actually found

when we'd come to wrapping all the metallic materials around it

and the ceramics and so on, is a lot of that disappeared

for all kinds of reasons, and for the first three or four years,

the activity was simply to try and find out why we had done so badly

with real engineering relative to the ideal.

And that was down to the actual configuration of the aeroplane.

We resolved that very quickly.

Computer modelling allowed the team to question every assumption

behind HOTOL's configuration,

and redesign it from the ground up.

We decided to literally start with a clean sheet of paper.

And the way we did that was,

we took the engines off the base of the aeroplane,

and we put them actually onto the wing tips.

With one bound, Jack was free

and we got a very efficient solution to that problem.

The solution was a complete overhaul of the airframe.

The new craft was named Skylon.

Although they had designed it,

Bond's new company, Reaction Engines, would not build the plane,

but develop the engines that would allow Skylon to fly.

Whilst Bond continued to work

on developing the original HOTOL concept, NASA changed tack.

It abandoned rocket technology altogether.

Instead, it turned to a development of jet-engine technology,

called scramjet.

Scramjets work much like a modern airliner,

but use their own speed to compress air into their jet engines.

Scramjets are air-breathers,

that obtain oxygen from the air in which it's flying.

This characteristic allows for much more aeroplane-like operations,

with increased safety, affordability and flexibility.

Scramjets are beautifully simple.

They have no moving parts.

A conventional jet has a series of blades

to compress air into the engine.

In a scramjet, however, there are no blades.

The incoming air is compressed by the craft's sheer speed alone.

But as engineers found, igniting fuel at Mach 5

is about as hard as striking a match in a hurricane,

and keeping it lit - harder still.

Nevertheless, NASA was confident that scramjet technology

would shape the future of manned space flight.

The ultimate goal of hypersonics really is twofold.

One is to reduce the cost for access to space.

The second goal, and probably one that's further out,

maybe 100 years out,

but hypersonic commercial travel, I think, can be a reality someday,

and going anywhere on the globe in just a few hours.

Actuator on my mark.

Three, two, one, mark.

In 2004, NASA's X43 technology demonstrator

set a new airspeed record for powered flight,

reaching an incredible Mach 9.8.

But scramjets can only function at velocities greater than Mach 4

and must rely on chemical rockets

to boost them up to their operating speed.

As a result, NASA now doubts

that a single-stage-to-orbit spacecraft will ever be achievable.

Console on.

WHIRRING

Just as NASA was announcing the death knell

for single-stage-to-orbit vehicles,

back in the UK,

Bond's team had made a breakthrough in their engine design.

In 2004 we found an entirely new avenue

which we could evolve with these engines.

And the thermodynamics continues to evolve even now,

so we are currently working on an engine

which has half the fuel consumption

of the SABRE engines that we designed in 1993 for the Skylon vehicle,

which in itself was more than 50 per cent improvement

over the engines in HOTOL.

So I don't think we're near the end

of what these engines are actually capable of at this point in time.

To bring the original HOTOL concept to this stage

had taken Alan's team some 15 years.

Along the way, they'd had to overcome a series of obstacles,

which might easily have broken a lesser man.

When Alan first formed Reaction Engines to develop HOTOL's legacy,

the engine he had designed had been classified Top Secret,

and its key features patented.

The actual patent restriction ended in 1993.

The patent had actually been acquired by Rolls-Royce,

for a finite period of time, and it was quite clear

that no further development was going to take place on that engine.

So I set out to find a way to circumvent the patent

in order that we could actually complete the work on it.

Now, I wrote the original patent, so I'd written it in a way

that I didn't think it could be circumvented.

But what we had found during the course of the work

were a lot of thermodynamic nuances within the engine.

And that meant that the engines were capable of things

that in the 1980s I hadn't actually realised.

Having overcome the legal obstacles,

the team now faced a series of daunting technical challenges.

We need the thrust-to-weight ratio of a rocket engine,

but we need the fuel consumption of a jet engine.

So we're basically trying to stitch these two technologies together,

but in order to do that

we need to develop these lightweight heat exchangers.

The key to Skylon's revolutionary engine is its ability,

like a jet engine, to compress incoming air.

Then, like a rocket engine,

to use that air to burn the on-board liquid hydrogen to create thrust.

To do that, the compressed air must first be cooled

until it nearly liquefies.

And that's the bit that no-one has ever successfully done before.

The SABRE engine...

is effectively a jet engine and a rocket engine stitched together.

In order to make this work,

we need these very high-performance heat exchangers.

It is the heat exchangers

that make a single-stage-to-orbit vehicle possible.

Nobody's ever made this type of product before.

No-one's been able to make this type of product before.

The heat exchanger works a bit like a conventional fridge.

Liquid helium is passed through a series of very fine tubes.

Air passing over the tubes is then instantly cooled.

The problem Alan and his team faced

was to manufacture a heat exchanger with as many tubes as possible.

You can't just bend these tubes into any old shape.

They're very unique items, they're unique to Reaction Engines,

we've developed the manufacturing processes in order to build them.

If you take one of these tubes in your hands

you can very easily just break it in two.

So actually forming them into the shapes we need

is a very difficult challenge.

The air is a very poor conductor of heat,

so we have to do everything we can to strive for maximum compactness,

to maximise the heat-transfer performance

on the air side of the heat exchanger,

so a large quantity of these tubular-flow channels

of very small diameter

improves the heat-transfer performance.

Now, we've reached a practical limit

on the compactness that we can achieve.

That's where Reaction Engines is pushing the boundaries

on compact, lightweight heat exchangers.

The challenge here is to cool the air

whilst avoiding the frosting problem

that had bedevilled the original HOTOL project.

It took the team years of research to develop a solution.

But after their disastrous experience with Alan's HOTOL patent,

the team has chosen to keep their latest technology as a trade secret.

We've had a long research programme developing the technology

to stop this pre-cooler clogging up with frost,

and that is unique technology to Reaction Engines.

Trade secrets are how most industries survive.

We have a number of key technologies

and rather than patent those, which basically declares it to the world

how you've done it, what we do is

we basically keep those secrets as trade secrets

within Reaction Engines

and only Reaction Engines' employees are familiar with that knowledge.

The last major technical challenge facing Bond and his team

was getting as much thrust as possible from Skylon's engines,

all the way from the runway, right up to Earth orbit.

Teaming up with Bristol University and Airborne Engineering,

they're exploring techniques called altitude compensation

to make their rocket nozzles ultra-efficient.

Once upon a time you could have a small nozzle for sea level,

throw that away at the end of the first stage

and then have a bigger nozzle in the second stage,

which suits higher altitude - throw that away,

And on the third stage, have the biggest one that you can fit.

So, the advantages that are gained by this altitude compensation

are much more for a single stage, where you can't throw anything away.

All rocket engines work by pushing hot gases through a nozzle

to create the thrust needed to keep the rocket going.

But as the rocket gets higher and higher,

the size of the nozzle needs to get wider and wider

to maintain maximum efficiency.

Unlike the space shuttle, a single-stage-to-orbit vehicle

does not have the luxury of throwing away nozzles

with each booster stage,

so that the right-sized nozzle is always used at any given altitude.

The University of Bristol, to try and get round this problem,

focuses on something called an expansion deflection nozzle.

The idea is fairly simple,

it's a fairly standard shape for the outer contour,

but there's a plug up the middle

which goes up the centre of the engine

and causes a central void in the flow.

As you get higher, it allows the flow to expand in towards the centre line

so you end up with a more efficient engine.

-Just about to do a firing. All ready?

-Yes.

BEEPING

What we learned from these tests has been quite interesting.

The rocket engine expansion ratio is bigger than the space shuttle,

so the difference between the exit flow and the central flow

is greater than the space shuttle.

We ran that attached at 12 bar.

The Space Shuttle needs to run at 200 bar to keep it attached.

So we have managed to achieve some fairly impressive results.

Having reached space,

Skylon then faces the equally daunting task of returning again.

The Shuttle famously depended on thousands of ceramic tiles

to protect it from the intense heat caused by re-entry.

The rocketeers needed a lighter-weight solution.

They took their inspiration from an unlikely source -

an American spy plane.

It is drawn from the SR-71 Blackbird,

which had a corrugated titanium skin.

And when we started to look into the Skylon structure,

we decided that the solution that other companies had intended to advocate

which is using honeycomb panels of heat-resisting ceramic material,

was actually not the right way to do it.

And we could find a lighter solution

by adopting the solution that the Blackbird had used,

whereby we just take a single skin of material,

and corrugate it for stiffness,

but also for thermal compliance

from the substructure from which it's mounted.

During re-entry, the aeroshell is about 800 degrees hotter

than the internal structure of the vehicle,

so you've got a major thermal expansion mismatch there to solve.

If you imagine this is part of the aircraft's skin,

it could be part of the fuselage or the wing,

because of the corrugations,

it has a certain amount of stiffness in this direction.

However, it has relatively little stiffness in this direction,

so this panel, during re-entry, could be perhaps 800 degrees hotter

than the substructure from which it's mounted.

It's silicon carbide fibres within a glass matrix.

And this material is good to around 1000 degrees C, we think.

May I have your attention, please?

A temperature run is about to commence.

While Alan's team was drawing on American technology for heat shields,

the United States Air Force had continued to develop the scramjet.

What we are going to do is we are going to take the X-51 Waverider.

We're going to launch that from a B52 at 50,000 feet

over the Pacific Ocean.

And then the vehicle is going to drop away,

it's going to be accelerated by a solid rocket booster up to about Mach 4.5.

The solid rocket booster will drop away and the vehicle,

and the engine, that's just being tested,

is going to ignite and then further accelerate that vehicle up to Mach 6.

The Waverider is the successor to NASA's X-43 scramjet.

But it is designed for conducting warfare, not space travel.

Everything we do at Edwards is flight test

and a lot of what we do is weapon systems -

in the short to middle term -

helping the war fighter more directly.

This is more of a long-term thing.

Things that we're working on in the scramjet engine

are going to benefit the war fighter 15, 20 years from now

when we're will be able to utilise this technology to bring new capabilities to the fight.

It's exciting, though.

NASA had hoped that scramjets would deliver cheap access to space.

But the US Air Force sees scramjets as forming spearhead of prompt global strike -

a military doctrine adopted by the US as part of the war on terror.

Space travel is no longer a goal.

As a means of getting a warhead to any target on the face of the planet in under 15 minutes,

scramjets' disadvantages are of little relevance to the US Air Force.

With scramjet technology firmly focused on military use,

the Skylon team are confident that their own engine design

will now emerge as the sole contender in the race

to produce a single-stage-to-orbit spacecraft.

Our other main competitor in propulsion terms is

the so-called scramjet, supersonic combustion ramjet.

On paper, the scramjet has a sort of siren-like attraction about it,

because it's capable, in theory, of producing useful thrust,

up to some very high Mach numbers.

Perhaps Mach 10 or even 15, on paper.

However, unfortunately, scramjets are completely unsuitable

for propelling an aeroplane into space.

A scramjet, like a ramjet, has no compressor.

So it's not capable of operating from rest.

It has to be accelerated up to some suitable Mach number

before the engine can even generate any thrust whatsoever.

With all the enabling technologies that would turn Skylon into a viable spacecraft now established,

the three rocketeers' lonely years in the wilderness are at last coming to an end.

The journey has been long and arduous.

My overriding feeling is just a sheer waste of time and effort

that's gone into this.

I'm now in my mid-60s.

I really wish I was in my mid-40s, trying to do the same things.

My colleagues have spent a large part of their career

in the wilderness.

We could have done so much more.

You have to remember that originally

HOTOL would have been going to orbit in the mid-1990s

and here we are at least 10 years on from that.

So sad that it's taken us so long and there's been so much wasted time,

especially so much wasted British industry in the process.

From his early work on HOTOL to the present day,

it has taken Bond and his team over 30 years to turn his vision of cheap access to space

into something a lot closer to reality.

There have been many dark days and the real dark days

is when you carry a vision into sort of various government departments

and you feel that people can't see past the first paragraph

of that vision.

But today, vision seems to focus on bank accounts and material wealth

and various celebrity programmes and so on.

The actual vision of doing something bigger

on the basis that the future depends on it seems to have been generally lost.

At an age when many people would be looking forward to retirement,

Alan continues to pursue his dream with passion and determination.

A lot of people have regarded me as having the vision.

I've been fortunate that I've had a large number of colleagues around me

who've also been able to share that vision.

The potential that this technology can add to the science of propulsion

is phenomenal.

Inspired from his boyhood days by the Dan Dare stories,

Alan Bond has devoted his entire life to the dream

of getting mankind into space.

Shrugging off government obduracy,

lack of funding and international scepticism,

he and his colleagues have struggled on against all odds.

Now, more than two decades after the HOTOL Project was shut down,

today's test will decide whether the pre-cooler actually works.

And, with it, the possibility of building an engine

that would allow Skylon to fly.

ENGINE PICKS UP SPEED AND ROARS

The very future of reaction engines itself

depends on the outcome of this test.

The years of hard work pay off.

The pre-cooler works flawlessly.

Alan's vision is finally taking shape.

As of now, Skylon itself remains just a vision.

So far, no-one has come forward to actually build the first prototype.

But such details are of little concern to Alan Bond.

We have absolute confidence in the technology.

I've devoted well over 20 years now into developing this

for the sole reason I'm absolutely sure that it's all going to work.

After a lifetime's devotion to this single dream,

Alan can at last look forward to that dream becoming a reality.

Ten years from now, the first Skylon light vehicles

will be flying into orbit and someone will be looking at the Mark 2.

I like to think of Skylon as the DC3 of the space business.

And somewhere downstream there are the 747s and the 777s.

For the three rocketeers, it has been a lonely journey.

But as Alan approaches his eighth decade stuck on this planet,

at last other people can now see his vision.

There is a new generation of people that do feel

that there's some merit in what we're talking about.

There's a generation of people within government departments in the UK

that feel that there's some merit,

and they have conveyed their views on that to the European Space Agency.

And I do feel that we now are experiencing a seachange

in terms of getting the project moving.

We're standing today, I think, on the verge

of a new era of transportation which will be brought about by these engines,

and I think the possibilities are probably endless.

In a few decades from now,

we'll be able to put anything that we want in space as easily as

we could get on an aeroplane to go anywhere else in the world.

Although I'm slightly visionary,

even I cannot see what the ultimate consequences of all of that are.

Subtitles by Red Bee Media Ltd