Love, Death, Chariot of Fire Page 14

  ‘So it’s a case of softly-softly-catchee-monkey?’

  ‘Yes. On top of that, we don’t want our competitors and potential enemies sniffing out what we’re doing. So poor old 224 still has its uses as a decoy. It’d be helpful if outsiders continued to think of that lame duck as representing our most forward thinking.’

  ‘Who’s our main competitor at the moment?’

  ‘Hawker’s, believe it or not – assuming that none of the current crop of F.7/30 prototypes passes muster. Sidney Camm has at last been persuaded to design a low-wing monoplane fighter, I’ve heard on the grapevine.’

  ‘How’s he going about that?’

  ‘Basically by tinkering with his most recent biplane fighter, the Fury. Adding a canopy over the cockpit. Removing the upper wing while greatly increasing the wing span. Hoping Rolls-Royce will soon provide him with a more powerful and reliable engine – the one we’re waiting on too. And not much else. Same old chassis-based airframe, same old canvas skinning for the most part. No thought to the advantages of an integrated monocoque airframe. Or stressed-metal skinning to support it.’

  ‘Doesn’t sound promising. But Camm is very good at what he does, even if he’s a bit old-fashioned. You’ve got to grant him that.’

  Mitchell feels a sudden agitation. He gets up and starts pacing the floor between the desk and the window. The air coming through the window seems warmer now; he opens it a little wider.

  ‘All right, Bev. His contribution might turn out to be a fast and serviceable fighter all the same. And a stable gun platform. But this country is on its way to losing air parity with Germany, if it hasn’t already done so. If and when the buggers come for us, they’ll have a lot more planes than we have!

  ‘So we’ll need something better than Camm’s machine. Something that breaks new ground in speed and agility. Something to which there’s no answer – that can even the score. Bring down the Nazis’ planes in droves! Keep the bastards’ filthy jackboots off our soil!’

  Shenstone registers astonishment at Mitchell’s vehemence, then smiles. ‘You can count me in, RJ!’

  ‘Thank you. Right then, so much for the competition,’ Mitchell resumes his seat. ‘Now, what about the potential enemy? Do you still have tentacles into the world of German aviation?’

  ‘A few. But they’re pretty attenuated given the current regime there.’

  ‘Well, what have you heard or read about the Germans’ fighter development?’

  ‘They’re at the same stage we are. Early last year the German aviation ministry put out a spec for a single-seat fighter and invited interested firms to enter their designs to meet it. Two months ago it signed development contracts with three firms whose designs appealed to it. These firms have to have their prototypes ready for testing by the end of this year.’

  ‘Which three firms?’

  ‘BFW – Bavarian Aviation Works – Heinkel, and Arado. BFW has its nose in front, I’ve heard. With a design code-named Bf109 by Willy Messerschmitt and his sidekick Robert Lusser.’

  ‘What do you know about it?’

  Shenstone shrugs. ‘Not much. I’ve heard that it’ll have strangely small tapered wings ending in square tips, with slots along the leading edges for added lift. In other words: pretty conventional, in a Teutonic sort of way.’

  ‘Small wings are hardly conventional.’

  ‘No, they’re not. You’re right, RJ. The small wings indicate that the plane’s meant to be very fast. But if what I’ve heard is accurate, then it’ll face three problems – heavy wing loading when manoeuvring; therefore thick, draggy wings; and lack of a suitable power plant to pull it along. So far, at least. It’ll be a monster to fly, too.’

  ‘You don’t sound impressed. What happened to all that brave research and experimentation you saw when you were working at Junkers and that gliding place? What was it called again?’

  ‘Wasserkuppe. Well, I imagine that the current Nazi overlords are their own worst enemies here. They’re anti-intellectual blockheads. They don’t like or trust the theoreticians and mould-breakers like Hugo Junkers, Claudius Dornier and Alexander Lippisch. Keep wondering if they have Jews in their family trees, would you believe! What the hell has genealogy got to do with aircraft design?! The dislike and distrust between the Nazis and the brighter German designers are mutual, needless to say. Messerschmitt has become prominent only because he’s a Nazi, not because he belongs in the front rank of German designers.

  ‘And the regime can’t see it’s shooting itself in the foot?’

  ‘No, RJ. So I’m not sure how many subtle insights and esoteric research findings will make their way into any of the new German prototypes. The political bosses in Berlin will presumably favour quantity over quality anyway. They’ll demand simple aeroplanes that can be mass produced in short order. In the end, I suspect, we’ll be taking a lot more advantage of the work of Junkers, Lippisch and co than the German air force will.’ Mitchell has been leaning forward over the desk, listening so intently to his young Canadian colleague that for a moment he fails to respond to the end of his exposition.

  He recovers himself. ‘Thanks, Bev. That’s very informative. I’ll show you my preliminary sketches for the Type 300 in a moment. But first a word of explanation. Obviously I want a plane with lean, clean lines that minimise drag while maximising speed, climb rate, and manoeuvrability at all altitudes up to 30,000 feet.’

  ‘Right. But how will it be powered?’

  ‘I’m assuming that Rolls-Royce will come good with a new, much improved engine that’ll deliver a thousand horsepower but will weigh about a third more than the current Goshawk. That’s the price we’ll have to pay for the additional 400 horsepower. The plane must achieve a speed of 350 miles an hour at least in level flight – we need the extra horsepower to attain this. And Arthur Sidgreaves at Rolls-Royce has more or less promised it to us.’

  ‘Holy Moly! That’s a hundred miles an hour faster than the current specification! Isn’t that going to add to the problems we’re already having with the present 224 prototype’s evaporative cooling system?’

  ‘Yes and no. Yes, for the moment we and Rolls-Royce are still assuming we’ll need to retain and somehow improve on the current evaporative cooling system. And maybe no – a far better alternative may be in the pipeline. A chap called Fred Meredith at the Royal Aircraft Establishment in Farnborough is working on an idea for a ducted radiator system that dissipates heat much faster. At the same time it’d force hot air out aft, so adding enough thrust to counteract the inevitable drag created by its forward-facing air intake.’

  ‘If Meredith succeeds with his idea, then we won’t need condensers, collection tanks, pumps, and all that piping. Have I got that right?’

  ‘Yes you have, Bev. And we’d use ethylene glycol as the liquid coolant. It has a much higher boiling point than water, so there’d be no need for evaporation or condensation. And this system would greatly reduce the volume of coolant that the plane would need to carry.’

  ‘What a major step forward in performance that’d be! OK, so what other innovations are you looking for in the new plane’

  ‘I want to overcome the present tendency for high-speed aircraft to need wider and wider turning circles. I want our new one to be able to turn on a sixpence while losing as little speed as possible. I want the controls to be light and immediately responsive. Above all, I want it to be safe – not break up in mid-air.’

  Shenstone whistles softly. ‘My God, you’re not asking much!’

  ‘There’s more to come, I’m afraid. To do with armaments. A certain Squadron Leader Ralph Sorley at the ministry is mounting an argument that – if a fighter is to have a chance of disabling one of today’s fast metal-skinned bombers – it will need eight forward-firing guns. The higher-ups in the ministry are coming around to that view. So am I.’

  ‘Eight! That’s double the number in the current spec.’

  ‘Think about it, Bev. These days a fighter pilot can only hold a targe
t aircraft in his sights for two seconds at most. In those two seconds he has to spit out an awful lot of rounds to have any effect. He’s only firing infantry-calibre ammunition, after all. Fortunately Browning should soon release a more rapid-fire gun. Still further down the track we should have a reliable cannon that can replace two guns. A direct hit by just one of its shells will bring a plane down without fail. Those foreseeable changes won’t affect our basic design, though.’

  ‘But eight guns will add considerably to the plane’s weight. Think of all the extra ammunition it has to carry!’

  ‘Not necessarily. Squadron pilots can be trained to fire only when their sights are locked onto the target, instead of just blazing away and not hitting a sausage. So we can use smaller ammunition boxes spread more evenly along the wings.’

  ‘All right, RJ, I’ll take your word for it.’

  It’s time for a precautionary pit-stop. Mitchell stands up and passes over his battered clipboard to his colleague. ‘I’m going to the lav. Have a quick flick through these sketches to get an idea of what I have in mind. Then I can plunder your ideas when I get back.’

  When Mitchell returns, Shenstone is hunched over the drawings in intense concentration, leafing backwards and forwards to relate the various profiles to Mitchell’s overall brainchild. He doesn’t react as its creator walks behind him and around the desk, pausing to look out of the window and open it fully.

  Mitchell turns his chair to an oblique angle to the desk so as not to engage his visitor too soon. It’s time for a smoke, which serves the added purpose of masking any smell he might be exuding. In the comfortable silence, he takes out his pipe, uses his pipe knife to scrape the ash out of its bowl onto an ashtray, runs a cleaner up through the stem, and slowly repacks it from his tobacco pouch. Having pressed the tobacco down with his tamper, he lights up.

  Given Shenstone’s capacity for mental absorption, the whole morning might have passed in this way, but for Vera’s entrance with tea and biscuits. Shenstone looks up at her with the surprised look of a man woken from sleep, and thanks her. He looks across the desk with the same surprise to see Mitchell once more seated opposite him, puffing on his pipe. He takes a packet of cigarettes from his jacket pocket and lights up too.

  ‘You mustn’t like the Germans very much, RJ, if you’re intending to hurl this thunderbolt at them,’ Shenstone chuckles.

  ‘The friendship has indeed soured over the last eighteen months, I have to admit. But this is a short-range weapon – only the trespassers into our airspace will cop it.’

  ‘Well, let me first congratulate you. It’s a beautiful, spare form, and not just to the aerodynamicist’s eye. Look at that slim fuselage! And I bet you won’t put up with too many extruding bumps or blisters, and you’ll insist on flush rivets. Smooth as a baby’s bottom, so minimal skin friction! It’s true sculpture. The family resemblance to your Schneider racers jumps out at me, of course.

  ‘I’d say you’re well on your way to creating your fighter to which there’s no answer. I notice, though, that you’ve left the wing planform vague. Is that where I come in, then?’

  ‘That’s precisely where you come in, Bev. My whole concept depends on the wings above all. But try as I might, I can’t see how any wing that I’m familiar with can do the job – accommodate the retracted wheels, the guns, and probably radiator scoops – while still maintaining a high lift coefficient, thin wing profile, and high-speed control and responsiveness.’

  ‘Would you be open to elliptical wing edges?’

  ‘Wide open! I don’t give a bugger if the edges are straight and tapered, or elliptical, so long as the wing does the bloody job. So go ahead – convince me!’

  ‘Well first up, let’s scrap the idea that ellipses are new or exotic or impractical in aircraft. People have tinkered with them for flying machines – powered and unpowered – since late last century. Not just for them, either. You’re a sailor, RJ – you’d have seen lots of mainsails on yachts, ones with concave ellipses forming their trailing edges.’

  ‘I hadn’t thought about it before. But yes, you’re right.’

  ‘Other flying and swimming life-forms have deployed them since long before we came down from the trees, too. There’s been a lot of study of the phenomenon in birds’ and insects’ wings, and even in the zanonia macrocarpa seed.’

  ‘The what?!’

  ‘This plant is a sort of pumpkin that grows on a vine high up in rainforest canopies in Java. The seed it releases has swept-back, elliptical, papery wings. When it detaches from the vine, it can glide extra-ordinary distances before landing. That’s how the plant spreads. Being a plant, it lacks any intelligence that could trim its flight – not even an avian or insect brain. So its wings are seen as the last word in aerodynamic balance. There’s been a lot of scientific work done on it in recent years. Not least at the Kaiser Wilhelm Institute for Aerodynamic Research in Göttingen, when Professor Parkin and I visited it three years ago.’

  ‘Now I’ve heard everything! All right, so flying ellipses exist in nature. I get the picture.’

  ‘Well, not just in nature – in supernature as well. If you look at depictions of angels with their wings outspread, you can see that the trailing edges are usually elliptical too. Same goes for most fairies. Artists often have an intuitive sense of the rightness of things, and that’s presumably how the angels and fairies got their elliptical wings.’

  Mitchell struggles to keep a straight face. He detects the earnest tone in his companion’s voice, and remembers his promise to keep an open mind.

  ‘Splendid. But how can an ellipse – or ellipses – help our Type 300?’

  ‘Well, I can only give you a very preliminary idea. Can you hand me your sketch pad and a pencil, please?’

  As Mitchell reaches for them, Shenstone lifts his chair around so he’s sitting closer and at right angles to him. As he starts to sketch the plane’s fuselage, as seen from above, across the middle of a fresh sheet of paper, Mitchell hurries to relight his pipe.

  ‘So here we go,’ Shenstone says. ‘I notice from your sketches that you’ve provided for the bigger engine with your Schneider racer-type long nose in front of the cockpit. You’ve also set the wing roots well forward to align with the forward shift in the centre of gravity. Good.

  ‘Now, in the few aircraft that have elliptical wings nowadays, the ellipse only forms the trailing edge. Or both edges are elliptical and symmetrical mirror-images of each other. But why not combine two asymmetrical ellipses, with the deeper ellipse on the trailing edge and the shallower one on the leading edge? Then let them meet in a rounded wing tip.’ He illustrates his point by adding the wings he’s describing onto the fuselage he’s already drawn.

  ‘Why would we match asymmetrical ellipses?’

  ‘A number of reasons. We’ll need a very strong spar under the skin just behind the leading edge and closest to the centre of pressure on the wing. This is where the heavy gear – guns and wheels – will be housed, too. And the gun barrels in particular should be at right angles to the leading edge, or very close to it. Finally, this layout reduces the lateral airflow along the wings – the “washout” in other words – that can create turbulence and drag if it’s not carefully channelled.’

  ‘So this is all about the mysteries of airflow, is it?’

  ‘Yes, absolutely. Although it’s no longer as mysterious as it once was, thanks to recent mathematical calculations and experiments in wind tunnels. As well as invaluable discoveries made at the Wasserkuppe research station.

  ‘And where does all that wisdom get us?’

  ‘It reveals ways in which we can fine-tune shapes and skins so as to maximise lift and minimise turbulence in the wings’ wake – wing-wake that acts as a brake and necessitates big tail sections to keep the aircraft steady. Big tails are yet another drag element. If we can get the thinnest possible wing to cut through the air like a hot knife through butter, then the two airflows from under and over the wing can come together again
smoothly behind it – layering nicely, without creating vortices.’

  ‘Hmm. The way you’ve drawn your wings onto my fuselage makes the whole plane actually look like an angel with outspread wings.’

  Shenstone nods. He doesn’t seem to have noticed the likeness himself.

  Mitchell’s mind is racing. He feels like an apprentice at night school again, and rather enjoys the experience. ‘So let me try to guess the next bit. If the plane is leaving a much less churned-up wake behind it, then the whole tail section won’t receive nearly as much buffeting. In which case we can make it smaller without loss of control or stability.’

  ‘Quite. You’d be able to reduce the tail substantially from the proportions you’ve given it in your sketches. Which would deliver greater speed. But there’s more to this airflow story that I haven’t come to yet.’

  ‘Go on, then. I’m all ears.’

  ‘The ellipse form just expresses the general truth that rounded shapes and joins contribute enormously to aerodynamic efficiency. So square and raked wing tips are out, as are flat fuselage panels and angular cockpit canopies. But so are simple angles between straight lines where the wing’s trailing edge meets the fuselage. These cause considerable drag and turbulence. What we need is…’

  ‘I know – fillets!’

  Both men lean back in their chairs and laugh at the schoolroom interaction that’s developed between them.

  ‘Quite so, RJ! So let’s add them into our sketch here.’ Shenstone draws triangular panels into the plane’s armpits – although the hypotenuses are concave, aping the top of an ellipse. ’These fillets will prevent vortices forming, add to the wing’s lift, and help protect the reduced tail section from buffeting. The fillet panel might be quite large in area, but light. Worth its weight in gold with its contribution to a smooth airflow, as well as lift and enhanced control.’