Historic Aircraft Matter
Introduction
As a means of generating income for our competition activities in the 60s and 70s Aerobatics International took part in many aerobatic displays. As members of the Tiger Club the same people did the same thing as enthusiasts, for neither personal gain nor fame and fortune. It was all quite professional as far as standards go. People crashed at airshows now and again, sometimes destroying historic aircraft, and killing others. It was only while reviewing various historical events from the detached position of retirement that the enormity of these terrible and unnecessary events became evident.
The difference between competition aerobatics and air display performance - risk management applied or overwhelmed - why do some pilots crash at air shows?
An Apprenticeship
In defence of the competition aerobatic sport it has to be acknowledged that the level of comprehensive aircraft handling skill required, the discipline of formal manoeuvring requirements and the lack of appeal to the public as well as the romantically inclined pilot all contribute to a creditable level of safety in formally organised aerobatic competitions. This feature is in contrast to the air display scene for a simple reason: there is no status to be gained in a formal competition by attempting a manoeuvre you cannot carry out with recognisable success. The most effective policy for a competition pilot confronted by this improver’s problem would be to leave the figure out and score a simple zero, or fudge it with something similar that you can do. It just might even get a few points, but, whatever the score, your flight continues without added risk. Some observers may even recognise the tactical common sense; but, significantly, you will be alive to continue the learning process another day.
Self delusion
Performing ones own script (or, much worse, improvising to fill in empty time) in front of an expectant but uninformed airshow crowd is a very different matter - exciting though difficult fun if you know how, but very disappointing if you don’t. Stepping into Rome’s Coliseum arena on a Saturday afternoon without having attended gladiator school would cover it, yet some are tempted beyond their ability to resist. Inexperience may not have the opportunity to recognise itself until it’s too late, but even worse is the crime of a deliberate attempt to step outside one’s capability box in the hope that Lady Luck will somehow come to your aid, and make you look like the hero that lives in your imagination. Physics is not interested in such illusion, even if such fantasy is encouraged by the competence of others or the entertainment industry.
Criminal insanity
The dramatic and damaging results of the narcissistic and self-delusional pilot who gains access to a performing aircraft at a public event should not be explained away by the kind press and the public’s fondness for heroes. Society sometimes requires heroes, but they tend to do their heroics in relative privacy, learn from the experience and move on - even to perform safely in airshows. It’s the wannabe hero or those they might influence who can be a problem. Every case should not have happened, and one can think of many worst cases, but one particularly murderous event was the Douglas Invader at Biggin Hill. I did not know the pilot, his abilities or his motivations, but can guess. The barrel roll he attempted followed a very common pattern, and became a sort of half barrel followed by a quarter loop into the ground, meeting it vertically at great speed, killing all aboard and instantly pulverising a historic aircraft of character, one of many which had served its occupants well in the past - once ubiquitous, now rare. You cannot call this sort of event an accident. There are no extenuating circumstances. The kindest but still damning description might be reckless killing - whoever gets killed.
Why humans are at special risk to themselves
As members of the primate division of the animal kingdom we share an instinctive caution of historically life-threatening cues, as well as the helpful skills. Apart from juvenile learning, these built-in instincts appear to be inherited - but this process takes a very long time and a zillion generations of disaster or success to become established. The special human level of creativity, imagination, and the urge to explore and accept risk in doing so also makes us by far the most gratuitously dangerous creature - to ourselves as well as others. Even the wary but curious cats get nine chances. The human world invents new threats for itself at a great rate. Compared even to setting sail across the sea, flying aeroplanes is something almost infinitely new; and tends to punish major mistakes rapidly and severely. Unless you have evolved as a bird there’s little that’s instinctive about flying, and the much vaunted human capacity for reasoning must replace instinct. But a particular feature of this highly socialised human firmware is a particular sensitivity to what (we imagine) others may think about us - whether justified or not.
Will the real Wing Commander Mitty please de-volunteer himself (or stay in the story)
Why does a pilot actively abandon the reasoning that raises man above the beasts (in theory), discard the safety net of altitude and/or the necessary skills and, in an instant of vanity-in-the-limelight, attempt something where personal ability falls short of what is required. The fact that the machine may be willing and able is quite irrelevant; as is the irksome knowledge that others are patently capable of steering it successfully around their chosen manoeuvres. And yet, who with experience of either competition or display aerobatics has not felt the impulse, in the heat and excitement of the moment, to do something impulsive - keep the show on the road - don’t stop in the middle - or worse; impress themselves instead of the watchers? One could replace the notion of vanity with the sense of occasion that goes with exposure to the footlights. The professional, conscious of the feeling, takes advantage of this concentration of the mind and performs reliably, at the least: but the secret Walter Mitty hiding inside an imposter may, of an instant, become the confused rabbit in the headlights.
The Right Stuff
There are many pilots with the considerable experience, skill, understanding and maturity of judgment required for satisfactory air display flying. The vast majority of them do not take part for a number of simple reasons: they have nothing to prove, to others or themselves - in particular. They have other things to do and people to please; they understand the psychological tensions, pressures and unhelpful distractions involved, and the probability of logistical shortcomings, and they have a realistic assessment of their own limitations, despite the strengths. The few of these who do successfully carry out demanding air display performances all share these same qualities, and choose to manage the ability they possess on an on-going basis. All of these are sane human beings. So what is different about these and those who should never have acquired the opportunity to make instant and huge public mistakes - with no excuses?
The instinct for impulsive improvisation against the odds seems to be a special male characteristic, driven by evolutionary urges; useful when communal survival is threatened, but inappropriate when employed during otherwise agreeable and unthreatening aerial entertainment. Its motivation can be argued about, but one cannot dispute that the loose cannon temperament can be a very dangerous thing when exposed to an audience. Age has little to do with it, but the absence of an appropriate apprenticeship together with a faulty self image can contribute.
Is the problem getting worse?
We live in times of unparalleled opportunity to consume combined with the luxury of liberal notions, equal opportunity without responsibility and the right to celebrity without ability. Paternalistic authority is in disgrace; elitism is to be discouraged; dumbing down theory provides opportunity for all - to achieve what, other than acquisition, consumption and celebrity? When we come to decisions about what others may or may not do the situation becomes blurred when the foregoing attitudes prevail. The post WW2 democratic utopia discovered by much of the western world, aided and abetted worldwide by relentless electronic communication, has undermined its own structures of decision. Compromise, accommodation and permission are the new virtues. This policy is expensive and wasteful in many ways. How are important decisions made, and by whom? Good question.
What’s needed: who actually knows?
When it comes to who should be flying airshows in aircraft of character there will be those of the peer group who know: but a secluded sage or the cloistered committee of three, whose discussions are private and whose judgment cannot be questioned, has become unfashionable - especially if the decision is ‘no’. Typical complaints - ‘It’s not fair, it’s not democratic, ‘they don’t like me’, - may all be true, but something short of democracy may be the best way to avoid disaster. Modern aviation management in general cannot be distanced completely from the tone of the foregoing sentences. Achieving the required standard is the critical civil aviation criterion, and it works well enough for the statistics accepted by the transport industry; but it may be worth pointing out that this is an inclusive policy - it includes anything better than failure level. The reserve of skill and the psychological stability required to manage the low altitude manoeuvring of a high performance tactical machine on a daily basis is considerable; to do the same thing occasionally in front of a crowd is something relatively special. Only the elite can make elitist decisions. Discriminate judgments are best made by discriminating people who are not compelled to agree with box-ticking and industrial one-size-fits-all thinking-style analysis (DIY psychology). At the sharp end of human endeavour, experience combined with instinct is much more comprehensive and works better (the common sense of those who know).
What competition aerobatics can reveal; and remedy - given a chance
It is not uncommon to encounter pilots, often aircraft owners, who enter an aerobatic contest and are disappointed when the result does not meet their expectations. There are two responses to this discovery:
Continue to practice, ask others and find out how the sport works, with an understanding that public acclaim is unlikely to follow, but valuable skills will be gained: or
Declare that the sport is rubbish, the judges must be wrong, and that air display flying is more fun and rewarding.
The second may be true, but both organisers and pilot should consider carefully an individual’s motives and possible reluctance to accept the reasons for the competition disappointment. Safe flying, especially at an air display, requires uncompromising self-critical honesty. This is difficult for some.
To cite exceptions to prove my case in support of competition I have, on two (only) occasions, seen potentially high risk, impulsive and mistaken decisions made in an aerobatic competition, and in both cases these involved pilots of some experience, unquestionably with the potential to achieve much in competition, teaching or display flying should they so have wished, but with not much exposure to this rather academic and revealing sport. Whether they took steps to remedy the shortcomings they had demonstrated for all to see I don't know. Competition framework and altitude traditions had saved them.
One had considered that his handling skills were more than adequate for good results, without a full appreciation of what stage fright can do to you when electing to perform in front of strangers: the other had recently acquired a state-of-the-art aerobatic machine which enabled him to incorrectly force the entry of an approximation to the correct manoeuvre. This short cut in the learning curve had also bypassed the correct recovery technique, and the multiple rotations with low recovery reminded one of Bill Bedford’s Hunter sales clincher in Switzerland. By his own admission Bill had forgotten the height of the airfield, but he had rehearsed the negative spin. A pilot at a contest should not be in the position to need to ask ‘How do I do this manoeuvre?’ or ‘What do I do if?’, but it is always better to ask than pretend. Both events applied to pilots from small European countries without the benefit of a well-established tradition of this civil sporting discipline.
There is no suggestion here that competition experience is an indispensable qualification for air display aerobatics - far from it - but it’s a good start for those without much institutional experience of flying highly manoeuvrable or high performance aircraft anywhere near the ground on a daily basis. Elements of military flying specialise in this very thing, and those who administer it take a great interest in making sure that damage only occurs to an enemy, not their own pilots and expensive machines. Those who operate these kinds of aircraft outside a military organisation are in a vulnerable position, especially if a passing acquaintance with such machinery, or the catch-all test pilot title can be used to impress others and gain access to the stage. If you cheat about aeroplanes who are you really kidding? Yourself, dummy. They’ll kill you (and spoil it for everyone else).
British Aerobatic Association - how it sets a good example for safe ‘extreme’ sport
The BAeA was formed in the 1970s in order to become the national representative body for the sport. A prime objective at this time was to gain government support for a permanent training site, but this was not to be in a nation that preferred boating, housing estates and ring road shopping development to flying. Our meeting with the sports council was not encouraging. Motorised sport was out, and our mere hundred members not impressive - ‘We usually deal with 100 clubs of the running, jumping and standing still persuasions’ - so it was clear that Great Britain was unlikely to emulate the Russians or even the French in supporting this oddball and privileged minority sport. But the compulsory structure of this new association brought dedicated contest organisation with it, replacing what had previously been done by Tiger Club enthusiasts, among others, without losing much of the aerobatic tradition and experience. Pockets of cost-sharing owners began to teach themselves and each other the rudiments of formal aerobatic handling in relatively far-flung parts of the United Kingdom, albeit with affordable traditional machines, and the once privileged but dwindling sport was now widening its acceptance and social availability. It is also valid to point out that renewed interest in aerobatics may have reflected concern that a post war change to general aviation principles (the aircraft as flying car) would remove aerobatics completely from the experience of the civil pilot.
Modern built-for-purpose aerobatic aircraft began to appear, and their simplicity, convenience of use and relative ease of getting round the basics meant that more were able to enjoy the sense of achievement in safe competition at recreational level. Both the teaching and learning of aerobatic handling took on the academic and logical approach that works best - each manoeuvre considered by its components, the step by step building block process. Neil Williams’ book indicated the concepts of the handling basics, and Colonel Aresti's masterly analysis of the great many elements that make up the complex manoeuvres of the formal sport may have had something to do with this acceptance of an efficient learning process. It may be of interest to note that the Colonel was a member of the Spanish Air Force, not the Royal version. Spain was once a great empire-building sea power, but Francis Drake from Plymouth changed all that, of course. Can it be that Spain had come to terms with this change in its fortunes by the 1930s, and returned to being just Spanish (European indeed), and came to accept the legitimacy of aeroplanes as acceptable toys for interested pilots?
Of course, part of military flying training is directed towards the development of fighting skills, but this is still applied flying - the aeroplane used for a secondary purpose, not just the acquisition of prima donna pure handling perfection for its own sake - and while aerobatics of a sort is an unavoidable part of military basic training, here it provides an insight, both constructive and remedial, into elements of what may be to come - it is not a specialisation per se. The remedial part is something like the instrument flyer’s recovery from unexpected attitudes and behaviours, and covers two subjects. How best to sort out an unintended dive at speed, and what to do if the machine stops flying as designed (‘departs’: US english) and either tries to rotate, or indeed succeeds in going round and round, apparently of its own accord. In either case altitude will be lost until the problem is solved, assuming enough of it remains. Air display crashes, almost invariably, demonstrate one of these two basic features which should have earned the destructive pilot a ‘bad fail’ somewhere along the display qualification road. Who can say where a piece of foundation had been missed and the surface concreted over? There will be some who know the answer, including the pilot: but the idea of human frailty combined with the need for institutional heroism has already been floated, and need not be discussed further here.
Constructive learning - minimal remedial training
The student of competition aerobatics learns a lot about looping and spinning early on, but not as emergencies. The spin, both positive and negative, is learnt as a deliberate, controlled and consistently repeatable manoeuvre, including recovery to order.
There are many loop-the-loop possibilities for aircraft that can achieve the manoeuvre, but the contest system first and foremost requires a circular shape because it is the most logical to assess, is quite aerodynamically efficient, and can be successfully performed with relatively low performance machines. This round example has a major advantage in that it starts and finishes in the same place with the same energy - same height and very much the original speed - with a considerable degree of reliability. It requires piloting finesse in terms of g loading, timing and careful control of lift coefficient over the top - some of which will be at a slow pitch rate and virtually ballistic (weightless) - but a good technique carries the correct amount of energy up to this point, and enables the engine to provide maximum assistance while induced drag is very low and the wings are not being called upon to do much work. On the other hand the wings have to provide maximum lift force at the bottom - both at the start and the finish - and it’s the well-judged control of these various and varying parameters, sometimes close to their aerodynamic limits, that form a good basis for orderly aerobatic performance, and makes an undesirable and surprise total loss of control unlikely.
Familiarity with these two otherwise problematic areas of handling, when applied to an aerobatic or training light aircraft, does not alone qualify a pilot to demonstrate an assortment of loops, half cubans and barrel rolls in a 5 ton, 2,000 HP vintage fighter, but it’s a good start. Naturally, the circular and straight line geometry adopted by the contest world is not entirely appropriate for heavy metal manoeuvring; it makes too many off-design demands on a machine intended to meet the compromise of load-carrying, high altitude performance and adequate manoeuvrability - but comprehensive experience of efficient looping technique and the careful use of gently parabolic, minimum induced drag flight to get the half rolls in without inappropriate overcontrolling (thus risking ‘departures’) can only be helpful. In addition, experience of performing within a set framework, and the routine planning that goes with it, can only be a display advantage.
More wrong stuff
Evidence by YouTube is a new and revealing public phenomenon. The camera rarely lies, and the details of unsuitable piloting revealed by a stricken aircraft’s behaviour frequently tell a more interesting story than the bare bones of an official accident investigation report. ‘Full elevator was applied’ may suggest a mistake, but how do we public know? Better might be some additional science: ‘Elevator control should not have strayed far from the centre of the cockpit at any time during the manoeuvre, but especially at the top, and the important and critical use of the other primary controls may not have been appreciated in the unusual circumstances in which the pilot found himself’ might have explained more. More succinct might be ‘The pilot did not know (enough about) what he was doing.’
YouTube reveals air display derring do from the world over. A frequent accident feature (though not often from BAeA territory) is the A-personality pilot who can afford a dedicated aerobatic machine and is particularly taken with its multi-rotational abilities in their various forms (in contrast to its intended purpose). Everyone’s personal computer can reveal examples of the ill-judged enthusiasm which allows the machine to take control of the display. This tends to occur in geographically large countries where individual expression has a freer rein, and distance appears to dilute the influence of well-ordered learning and the sharing of wisdom borne of experience. Once again the, as yet unasked, question can be mooted: ‘Who gives these small-town desperados permission to perform their disorderly rolling, flicking, tumbling and lomcevaking evolutions at a public event? The tragic and criminal subject of disasters which follow standing-on or falling-off the wing attempts are better not discussed, but here follows a detailed explanation of what is required for a predictable barrel roll . . .
Barrel rolling - the easy manoeuvre with easy fatal consequences
Aerobatics used to be - maybe still is - defined as attitudes of more than 60° at variance with straight and level. A loop is a 360° rotation in pitch, a straight and level (slow, by name) roll the same 360° of roll rotation. These are aerobatic manoeuvres with nothing in common. Technically, a 60° banked (2g) steep turn is on the aerobatic definition limit, and many non-aerobatic aircraft can achieve this manoeuvre. The pilot sees much of the scenery ahead passing the nose in a top to bottom direction. ‘I’m almost doing a loop’, he might claim. Not exactly, but he has a point. He is about to scratch the surface of Newtonian laws of motion, the dynamics of curving flight, and the geometry of the spheres (geometry on a sphere? Not really - but a cylinder? - Certainly).
The barrel roll is a true hybrid of two different things, part loop, part roll: perfectly coordinated in the ideal version to describe a corkscrew shaped flightpath - and yet it is the least of aerobatic manoeuvres for the aeroplane structure. It troubles the machine no more than an assortment of turning behaviours, and comes in a large variety of interpretations. The looping element does not have to gain and lose as much height as an equivalent loop - the barrelled loop is stretched out to the side to make the corkscrew shape. It does not feature in the competition syllabus, being too three-dimensional for suitable judging criteria (and is considered not aerobatic enough: it’s also true that conventional stability design features favour the barrel roll), and ‘up and around, continuing around and down’ could be a simplistic description, especially for a fast aeroplane packing plenty of momentum. Similar advice as for the safe military beginner’s loop - ‘plenty of g all the way round,’ may also appear to be helpful, but, for aeroplanes which are not completely at home with a full circular loop, anything but the correct coordination of pitch and roll progress around a barrel roll, especially as the top is approached, is likely to result in a downward expansion of the figure - leading to excessive gains of energy in the downward direction, and significant loss of height. General purpose barreling should stay high in the sky, or be directed a bit upwards if plenty of spare energy is assured, but the technique still has an aura of mystique about it for many.
As Bob Hoover was keen to demonstrate, the coffee should not spill during a barrel roll. A closed eye passenger should only feel a smooth cycle of vertical acceleration with no side loading: 3g perhaps at the start, reducing to almost zero and returning to the original 3 as normal flight is approached at the finish. It feels like a sedate loop and, once correctly started, the vertical element should almost look after itself, with relatively small elevator adjustment. Aerodynamics and the interplay of potential and kinetic energy do most of this work, but there’s an important addition: the roll attitude must keep up to schedule with the pitching progress, certainly not lag behind it, and achieving this may require careful aileron and rudder adjustment to keep the roll angle on schedule, and the nose pointing along the flightpath, thus avoiding sideslip. In this special respect jets are easier than propellers.
This rudder and aileron business can be considerably complicated by engines with propellers. The rudder position required to counter propeller slipstream, asymmetric blade angle, aileron drag and gyroscopic precession varies somewhat around the corkscrew, as the machine makes its simultaneous looping and rolling - fast and heavy at the bottom, slow and light at the top, then fast and . . . . - but if the first half is not correct, the second half will certainly be no better.
The start involves extra lift combined with roll, but here any resemblance to the steep turn ends: the pull starts first - maybe by not much, but definitely not the other way round - and by the time both g and roll are correctly applied inside rudder will have accompanied them. The initial rolling at an extra two g’s worth of lift coefficient generates more adverse aileron drag than rolling into a steep turn, and correct rudder coordination will keep the seat of the pilot’s pants squarely on the cockpit seat as the nose proceeds up and around the vertical circle that he has visualised ahead. After ¼ of the manoeuvre the nose will have reached the top of the tracking circle (the start points at one side of it) and the roll attitude should be 90°. This is not the top of the figure; its situation is equivalent to the straight loop’s upwards vertical, and there is more climbing to do, thanks to Newton plus engine. At this point the lift from the wings should be reducing as will adverse yaw as aileron drag reduces - so what should the rudder be doing? Less rudder is now required to compensate for the roll application, but what about the engine, still doing its rotational best? Which way round is it going - what is precession at reducing speed doing to us - is the propeller's yaw effect the same as during normal 1g flight? And where should the ailerons now be to keep the roll attitude up to schedule with the circle? Probably more is the answer to one of these questions, but, to quote ‘Round the Horne’, the answers will not be given here. These, and many others, must already be familiar to the pilot who wishes to perform the barrel roll at relatively low altitude.
At the top, where, like a loop, the nose passes through the horizon at start of its way down, the wings should be passing through an upside down picture - still rolling on schedule with the imaginary circle. This is a place where confusion, indecision or, worst of all, a seizure of panic, will surely lead to a problem. The machine itself is quite unconcerned at the combination of an upside down view of the world, looking closer than expected, feeling a much reduced weight, flying well at less than half the entry speed (but far from a suggestion of stalling). The accomplished aerobatic pilot has no problem with the unnatural view, a personal weight of 15 kgs which disagrees with the upside down picture, the temporarily slow progress back to normality, and the control positions required to achieve this. He can simultaneously process pitch, roll and yaw and their on-going requirements as three separate functions; this is not like the steering-a-car principle that the designers probably had in mind.
Readers who perform looping-cum-turning manoeuvring for a job, especially in the jet trainers so eminently suitable for this sort of thing, may well be marvelling that such simple flying can be made such a meal of. The foregoing description is intended to do just that, and encourage the would-be showman to become an accomplished aerobatic pilot before trying this easy manoeuvre - especially if his hapless aircraft was specifically intended to fly the right way up and has an engine that stops if upside down (more than one engine can greatly complicate the getting-it-wrong issue). The second half of the figure will not be discussed here, but a mention of classic mistakes is worthwhile - they usually happen at the top.
The anthropoid’s pull response to a fright. Along with many life situations this falling out of the tree instinct can be surprisingly strong, and take place astonishingly rapidly - I’ve seen it. ‘If in doubt - pull (whatever is to hand)’ is usually wrong - in all flying devices.
Giving up on the roll at the top (No, there’s nowhere else to go).
Slow the loop at the top in the hope of getting more height (No, gravity will rapidly compel the wings to try to fly inverted at a low speed, and the engine(s) may stop.
Aircraft with good performance and manoeuvrability, and designed to fly well upside down, have chances to escape from the top of a barrel roll, but for aircraft designed for transport of many kinds, there is no alternative but a correct second half (assuming a correct first half) if a large amount of sorting out height is not to be required.
Advice: Get some in! Learn your lines, rehearse - more than once. If you’re not 200% sure, don’t do it!