On this day the small plaza beside the BLOODHOUND Technical Centre slightly resembles a film set. Well, in fact at the moment it is a film set. A major international TV programme is filming a scientific documentary, and all the usual suspects on such a set are present and correct. Cameraman in short sleeves despite the cold but also wearing the de rigueur sand-coloured waistcoat with enough pockets to contain the assets of a small army corps, toting a TV camera with the general aura of a SAM 7 missile launcher on his right shoulder. Plus the presenter dressed in the slop-clothes which presenters wear to demonstrate it’s their brain you’re paying for, not their dress-sense. This one has a keen brain, which I have observed in prior discussion, but otherwise I wouldn’t know, because he has now switched from English to fluent Arabic for the filming. Gawd, I wish I could do that.
And then there’s the sound man, bearing a microphone on a long pole with a beaver rammed on top, which may well have made its eyes water. I imagine the beaver has rather lost interest by now, but the contrary can be said for the rest of mankind. I think it might have been first stated by Julius Caesar that if you want to create a crowd, simply bring in a film crew. Most of the BLOODHOUND Team are gathered around shivering, plus a great many passers-by.
Centre of attention and lens is Daniel Jubb, rocket expert to BLOODHOUND, who is going to demonstrate the properties of High Test Peroxide (HTP), the BLOODHOUND rocket oxidant, to the astonished world.
Now as I’ve mentioned before, Daniel is slightly built, always immaculately dressed, and has a moustache like the front view of a jet bomber. He is one of the most intelligent people on the planet. Now, wearing huge safety gloves and a massive pair of blue-rimmed protective goggles above the moustache, he looks slightly reminiscent – please forgive me, Daniel – of a Hogwarts professor in a Harry Potter movie. Standing behind a bench with a shot-glass of HTP nestling in a bowl of de-ionised water, he demonstrates what HTP does. Using tongs, he dips a tiny sliver – no more than the size of a fingernail – of silver-plated nickel fabric into the shot-glass. Silver-plated nickel gauze being the rocket oxidant catalyst, the HTP reacts instantly, punching a cloud of super-oxygenated steam out into in the winter air.
Me, I sidle round the far side of the building and light up my old briar pipe.
The BLOODHOUND team do not approve of smoking but are too polite to tell me so, possibly realising that I was a pipe-smoker long before the majority of them were born and ain’t about to kick it now. For my part I try to return the courtesy by not lighting up in their presence – and especially also in the presence of naked HTP – with the result that they are fairly used to me furtively sneaking off into dark alleys like Mack the Knife suddenly remembering he’s carrying a corpse which really ought to be disposed of before he bumps into a Rozzer.
Coming back around the building, I donate a few pinches of tobacco to a thimble-sized container not unlike my pipe bowl.
Away from the camera, Dan sucks up one tiny drop of HTP into an eye-dropper, and then very carefully drips that drop into the thimble. The tobacco instantly goes up like a small but determined Mount Vesuvius firework, spurting a fizzing gout of red flame gone in about two seconds.
Okay, on the face of it, a tiny demonstration. But there’s more to it than that. Especially since Andy Green a few minutes later dips a bare hand into the HTP, fails to burst into flames, and after smartly washing off in de-ionised water exhibits no effects whatsoever except a slightly bleached mark under his platinum cygnet ring on one finger, which will fade away over the next few days. (The mark, not the finger).
Funny-peculiar…
Which just goes to show HTP is real funny stuff – funny-peculiar, not funny ha-ha.
Andy dips his hand in it – and nothing happens. Daniel dips a fingernail of innocuous-looking fabric into it – and it starts to decompose vigorously into steam and oxygen. One tiny drop in tobacco – tobacco which would normally take maybe 40 minutes to smoke – and up it goes in two seconds in a spray of flame.
Funny-peculiar. In fact an ignoramus like me might be forgiven for eyeing the stuff with deep suspicion because you never know which way the dang cat’s going to jump – nothing, steam, or fire.
In fact HTP is a sort of water with twice as much oxygen in it as ordinary water. (Ordinary water being H20 – two atoms of hydrogen to one of oxygen – while HTP is H202; two atoms of hydrogen plus two of oxygen). Present it with a catalyst and the oxygen atoms get all excited and jump about causing it to decompose into steam, oxygen, and heat. A very great deal of heat. Tobacco it seems is a catalyst, such that this single little tiny drop of HTP instantly de-composed, produced enough heat to ignite the tobacco big-time, and further fed the conflagration with a highly over-rich oxygen content.
The difficulty, of course, is knowing what is a catalyst and what is not.
Andy’s hand was not a catalyst – and so nothing. Although I’d not care to get a few flakes of best Virginia on my paw and repeat the experiment. (Nor does a thinking person dip his hand in and fail to wash it quickly, because longer-term exposure is Not Good For You. And nor, very seriously nor, do you want to get it in your eyes).
Dan Jubb’s sliver of silver-plated nickel fabric most definitely is a catalyst, but for all practical purposes is itself non-inflammable – so no fire, just the hot steam.
The tobacco might have been the most visually spectacular demonstration – but in fact it’s the steaming shot-glass from Hogwarts which is really important. Daniel dips the catalyst into the HTP for a few seconds at a time and produces a lot of steam, which quickly dissipates in the cold breeze. Had he used a pint mug of HTP plus maybe a coffee filter-sized cone of catalyst on a no-wind day the steam would have filled the whole plaza in maybe a second and a half – completely harmlessly, because the high temperature would dissipate immediately, and all else it’s doing is releasing extra oxygen into the atmosphere. And most cities can certainly use any extra oxygen which might be coming their way.
No – it’s when you start to do a few sums that you begin to get a thoughtful look on the front of your head.
Multiply that coffee cone – maybe four inches in diameter, with a surface area of about 13 inches – into a disc of fabric 16 inches in diameter. Which has an area of 201 square inches. There is a sample inside the Doghouse… sorry, the BLOODHOUND Technical Centre.
Now multiply that 201 square inches by 80 – yes, eighty – because there are no less than eighty layers of them in the two-inch thick Falcon rocket catalyst pack. That adds up to 16,080 square inches of cat-pack. Of a monetary value I could probably retire on.
Fed, in the 18 inch diameter Falcon rocket, not at atmospheric pressure, but with 900+ litres of HTP delivered within a duration of 20 seconds at a pressure of 1,100 psi through a pipe about the size of a drainpipe, courtesy of the Formula 1 engine driving the fuel pump developed from the Stentor missile. (See From Cold War to Car).
So… so far we’ve got HTP decomposing as a monopropellant, temperature rising to some 600 deg C as it exits the cat-pack, producing very high pressure as a result, and said very high pressure squeezing out of the rocket nozzle thus producing the thrust – somewhat eerily, without any flame (see the video on Rocket monopropellant testing under way). Well, there won’t be any flame, will there, because this is super-heated steam. And at this pressure and velocity, invisible except for heat-shimmer…
This is the rocket in monopropellant mode, using HTP only. Producing a thrust of 10,000 lbs. Enough, coupled with the 20,000 lb thrust of the EJ200 jet engine, to propel BLOODHOUND to around 800 mph.
Then add fuel
Ah – but that’s just the oxidant. Then you add the rocket fuel.
This makes an – ahem – more than slight difference. You line the 18 inch diameter by 12 ft long rocket combustion chamber with 181 kg (400 lbs) of solid-grain fuel – a sort of super high-tech rubber compound called HTPB. The de-composed super-heated HTP hits the fuel-grain – not with flame, but with sheer temperature – and the fuel grain ignites. So now you get the flame of rocket-plume, all right…
And the temperature instantaneously rises to 2,000 deg C, and further to 2,800 deg C in the compression at the nozzle throat. The pressure wallops up accordingly – and the thrust jumps from 10,000 lb to 25,000 lb. And maybe 13 seconds of burn-time further on, up to 27,500 lb…
A billion is currently regarded as 1,000,000,000. One thousand million. Multiply the fire of my thimble of tobacco by a billion X a billion X a billion – and you’re somewhere near the Falcon rocket.
Which, after about 18 months of semi-hiatus for one reason and another, is a bit behind its testing schedule. Well, all right, a fair bit behind.
But now about to catch up fast, thanks to the Cosworth Group. Now thee, me, and every other petrolhead in Christendom naturally associate the word Cosworth with car engines, and particularly race car engines. And rightly so. But in fact the Cosworth Group has evolved over the years into a much larger animal, and nowadays the vast majority of their work is in the realms of data electronics, control systems, and similar things I do not understand. They supply these things I do not understand to a staggering diversity of industries, ranging from aerospace to nuclear power stations to yachts to wind farms and heaven knows what-all else.
And now they are supplying electronics and rocket control systems for BLOODHOUND. Oh, and also (as I hinted a few months back) BLOODHOUND’s Auxiliary Power Unit (APU), in the shape of a Cosworth CA2010 Formula One motor. Or as many of them as it takes.
Now this engine is awesome. Having to be within the F1 rules it is a 2.4 litre 90 degree V8 which can rev to 18,000 rpm – which you, dear reader, might recognise as being noticeably beyond the speed at which any valve spring known to mankind can keep up with the proceedings. The result would be massive valve-float – massive enough to float the valves down through the pistons for example, leading to an interesting bang a nanosecond later. So the CA2010 valves aren’t closed by springs at all, but by a pneumatic air system operating at 20 bar – 20 times atmospheric pressure. This engine weighs 95 kg and develops 750 bhp with the potential of rather more when freed from Formula One rules and limitations. Which is a power-to-weight ratio of up to 10 times any road-going engine whatsoever.
It is also of course a tad more picky to operate than your road-able engine, requiring for example to be pre-heated before start-up, have the valve gear pressurised, and then be spun-up to 3,000 rpm on the starter motor before it deigns to fire up. After firing it will then typically idle around 4,000 rpm in an F1 car, although for BLOODHOUND it will probably idle – idle, forsooth! – at about 7,000 rpm because, say Cosworth, there is no particular requirement for slow running in this application. All of which would make it kind of anti-social in a London rush-hour, especially on open exhausts, but BLOODHOUND has no plans to operate in a London rush-hour, and for 750 to 800 hp from a 95 kg power plant they are quite happy to live with a certain degree of picky-ness.
And the Cosworth has enough electronic controls and sensors and telemetry on it to operate a small space-station. The exhaust gas temperature wriggles for a split-second passing 16,000 rpm in Sepang, Malaysia – which it won’t, but just say it does – and not only does it come up instantly on screens in the race pits, but less than a second later on identical screens at Cosworth’s Northampton base, bounced thereto by satellite and watched like hawks by a team of a dozen technicians who maybe have driven 10 miles to work so they can look into the innards of an engine running up to 18,000 rpm 12,000 miles away. Wonderful thing, technology…
Okay, okay. But all these electronic controls and sensors produce problems of their own. Quite apart from the practical bits like designing engine mounts, which takes the combined efforts of BLOODHOUND and Cosworth about a day-and-a-half – I exaggerate, of course, but it doesn’t take too long – there is the far greater issue of getting the Cosworth electronics to talk to the BLOODHOUND electronics. Cosworth are very, very advanced indeed in such matters, but nonetheless, this side is not simple. BLOODHOUND’s Senior Control Systems Engineer, Dr John Davis, is currently encamped in the Cosworth Design Office and will remain so for the next few months in the interests of everybody eating out of the same bag of microchips at all times. John recently reported that the Cosworth ECU data is available on a CAN link which can be read by Simulink software using a PC104 control card supplied by Formtech. I am personally delighted to hear this news because naturally I’d been worrying about it. Equally naturally I do not have the remotest idea what he is talking about – something about a can or two with the Cosworth guys, I guess, followed by a certain amount of Serbo-Croat which I did not previously know John could speak. Anyway, it all proceeds apace, and at the end of the day BLOODHOUND will be emitting something like 500 streams of telemetry every time it runs – much of which can be used for education as well as by the team, and most of which probably be still be Serbo-Croat to me.
Also proceeding apace is a more earthy mechanical issue – viz, that in the BLOODHOUND layout the CA2010 engine will be facing the ‘wrong’ way due to the positioning of the HTP pump. In other words, the normal back end of the engine – the clutch end – will now be facing forwards. So when BLOODHOUND is accelerating the Cosworth will think it’s braking, and vice versa – and this could produce an issue of oil surge. The CA2010 is certainly designed to cope with very abrupt forward G – an F1 car can brake from 125 mph to a stop in less than three seconds, notching up 5G in the process – but in the very nature of this, such braking does not go on for more than a second or two, and at this time the engine is not being called upon to produce full power under load, it being slightly unproductive to apply full grunt under full load and full brakes at the same time. In BLOODHOUND the acceleration will ‘only’ be 3G, but it will last for 40 seconds, which might give the 2010 a bit of a surprise. So part of the CA2010 test programme will be to run the whole caboodle – engine, gearbox, HTP pump and HTP tank – on a test-bed at full power and load whilst tilted 63 deg upwards (clutch end up) from the horizontal, to simulate the G. That should pick up any little problems which need the slight caress of modification…
From T&A to TARP – and maybe beyond
And when all that’s done will come the full test programme with said kit and caboodle linked up to the Falcon itself. The rocket tests will not be at Cosworth’s Northampton base because Cosworth most public-spiritedly do not wish to deafen the entire Northampton citizenry, nor relocate half an industrial estate into Lincolnshire by courtesy of rocket-blast.
Almost all the testing will in fact be at Falcon Projects’ very remote test facility in the Mojave desert in California, leading up to the final test and acceptance programme. (T & A).
T & A firstly involves working up to five full power, full duration firings on the test rig without anything blowing up, falling off, or otherwise going amiss. If anything does go amiss you scrutinise the remains, find out why, design-out the cause, and start again on the T & A runs. There is no chance whatsoever of the Falcon ever being ‘man-rated’ – NASA-speak for a rocket ‘cleared’ to be used with human beings sitting on top of it, such as in a Space Shuttle – because a test programme for man-rating would probably cost 20 times BLOODHOUND’s entire budget, delay the project until Hell freezes over, and even then not render said human beings into the A1 life-insurance bracket. No – the Falcon will always be an ‘Experimental’ rocket, and everyone on the team knows that, including Andy Green who will be parked in the hot seat in front of it. (Or thinks he will – my plans for kidnapping him and taking his place are advancing nicely, but please do not mention this to him).
The five full-grunt firings done, the Falcon team will then move on to the even more interesting stuff.
Testing to destruction.
They do not, of course, call it that. They call it Testing Above Rated Performance (TARP). They are not deliberately setting out to test to destruction – but if anything does destruct, why then you first make furtive phone calls to Los Angeles and Las Vegas to make sure they’re both still there, then dig the bits out of the crater and find out what let loose.
TARP, in fact, sounds scary – or if not scary, it will certainly do until scary comes along. But it is a most serious element of research, and will probably involve at least 10 full-power runs. Look at it this way: if anything does go bang, then I the driver – sorry, sorry, Andy Green the driver – would actually much prefer to be reading about it over my breakfast egg in leafy Bucks than sitting five feet in front of the thing at 800 or 900 mph when the aforementioned bang comes about. So TARP is a most serious scientific endeavour.
Quite possibly one of the most important research results, among many other important research results, which will emerge from the BLOODHOUND Project when all the tumult is over and done.
For example, Falcon will work up the oxidant pressure to 1,350 psi – way over the rated 1,100 psi, and the maximum the Cosworth and pump can perform. Then they will run it for a longer burn – 25 seconds instead of 20. Then they will run it with a tighter rocket exhaust nozzle than they’re using for real – a particularly important test, because if a nozzle fails it probably won’t go with a single polite pop, but blow out a segment first. Which will cause the rocket-blast to suddenly not be axial but to angle off a bit sideways or up or down or any combination of the above. And rather definitely one thing BLOODHOUND doesn’t need is a sideways kick in the ass passing through 900 mph…
And perhaps above all they will be testing the safety systems. Now BLOODHOUND will have more sensors in it than you can shake a stick at. Temperature sensors, pressure sensors, linear sensors, load sensors, you name it. All of which talk to the main computers, and most of which can trigger an abort at any time during the acceleration phase. Say the HTP tank pressure gets too low. The sensor tells the computers and the computers shut down the EJ 200 jet, shut down and de-clutch the Cosworth, shut off the HTP supply to the rocket, open the HTP tank pressure relief valve – all in an instant, far, far quicker than any human can react, even me. Oh, sorry again – of course I mean Andy.
And bristling with the mostest sensors of all the systems will be the Falcon rocket. It will have temperature and pressure sensors all over it like porcupine quills, plus – very importantly – load sensors in the nozzle flange mounting to detect any sudden off-axis thrust change.
So during TARP, Falcon will not only be testing the rocket and propellant systems – but also the safety cut-offs. And, odd as it may sound, testing them both ways – or in fact, three or four ways. First, obviously, to make sure they work in the first place. Which may – probably will – require loading up a rocket chamber with an artificial ‘hot spot’ to make sure the temp and pressure sentinels pick it up and the systems shut down in time before there is an inconvenient explosion.
Secondly – and apparently perversely – they need to find out if the system is too darned safe. If the sensors, and particularly the sideways load-cells around the rocket nozzle, are too twitchy they will cry wolf and trigger unnecessary aborts – which increases the risk to the whole project because there will then have to be more runs in a car which will naturally not be getting any younger with each whack at it.
Slight tightrope, there.
Especially since all sensors are inclined to become crotchety in a very high noise and acoustic vibration environment. And if ever there was a very high noise and acoustic vibration environment, the Falcon is it.
So Falcon will proceed to testing with some sensors deliberately failed, to see if the rest can cope…
You begin to see a pattern emerging. As TARP proceeds, these tests are inevitably going to become more – well, hazardous might seem a harsh word, but I hope and trust the observers will move out in an ever-widening ring and dig ever deeper trenches.
Because obviously you leave the most dangerous to last, because clearly you do not wish to reduce the TARP programme to smoking fragments right at the beginning. The highest risk of smoking fragments therefore comes at the end.
Such as simulating a ‘leak’ in the HTP tank nitrogen-pressurisation system and at the same time disabling part of the auto-abort, maybe deliberately creating a sensor-plus-computer failure which shuts down the HTP supply but not the Cosworth engine and pump. A very unlikely failure mode, certainly, but one which could instantly cause the pump to cavitate and send a water-hammer back up to the HTP tank which could then rupture…
Yeah. Leave that one until last…
Postscript
Just 40 years ago I was part of a team preparing for a motorcycle 24-hour Land Speed Record attempt. We carefully built the engine, added an oil pressure and temperature gauge and a more powerful headlight, and a couple of us invested in new riding gloves. Things have kinda changed…
