Turning heads

A display sequence should flow – each manoeuvre blending nicely into the next.

This is where the knowledgeable spectator can immediately differentiate between a true display pilot and an aerobatic competitor who is merely using airshows to get some reimbursed practise. Competition aerobatics requires a short, straight line to be drawn between each manoeuvre or figure, to show where one finishes and the next starts, with abrupt jerks into each new figure. This is ugly to watch, and I much prefer the flowing style you see in figure-skating or ballet – or from a proper display pilot.

An aerobatic display routine should also be comfortable to watch. Your spectators ought not have to lift their heads to look up at an angle of more than 45 degrees nor to pan left and right through more than 60 degrees. So you will probably have to start the first, higher portion of your display further away than the bare minimum separation provided by the nominated display line. Then, as you descend, you should plan to creep each subsequent pass ever closer to the spectators. You will also have to make them shorter.

Any aerobatic sequence is made up of a number of figures. Each figure might be constructed from one or two manoeuvres (or more in intermediate or advanced sequences). A half Cuban is 5/8 of a loop joined to a half roll, or a quarter-clover is half a barrel roll and half a loop. A slightly more complex figure might be a vertical upward roll with a stall turn or humptybump at the top and a flick roll or two on the way down. These figures are the building blocks of your sequence.

Research has established that, however capable you and your aeroplane may be, the audience’s concentration will start to waver after four minutes. As with after-dinner speeches, brevity is paramount, so you should stop with the crowd wanting more, and not wait until they’ve wandered off in search of another ice-cream. In my little Fournier, each figure takes me from 10 to 15 seconds, so 20 of them are quite enough for a four minute sequence.

There are several basic guidelines to aerobatic sequence design. These include generally looping into wind, so that the wind makes your loops look more rounded, and rolling downwind, so your rolls look straighter. However, in my slow-rolling Fournier, a four point hesitation roll takes so long and uses up so much distance that I now fly them into wind.

Similarly, a half Cuban should be started into wind, while a reverse half Cuban is begun downwind if possible.

Stall turns are best flown into wind, partly so that, if you don’t have an inverted fuel system, you can cheat a little and make the vertical component slightly short of perpendicular to keep your engine running.

Watch other performers and you will soon discern which figures are best flown in which direction.

Some manoeuvres, like stall turns, flick rolls and barrel rolls will cause you to move a little across the A-axis while running along it. Rather than considering this a disadvantage, these figures can either be used to battle an on- or off-crowd wind, or to bring your sequence closer to the crowd as you come lower. Unless you are very experienced (in which case you need not read this) or have an extremely capable aeroplane, and particularly if you will be flying to maximise your aircraft’s performance, you are likely to have to start your display quite high, gently descending from figure to figure as accumulated drag robs you of your initial potential energy. Although this is an overall disadvantage, you can make a virtue of your high start by using the extra altitude below you as a buffer for the more difficult or unpredictable manoeuvres.

After his first nasty accident, the great pilot and author Neil Williams said, “Never fly any auto-rotational manoeuvre in a low wing-loading aeroplane below 1000ft”.

That is exceptionally sound advice. I firmly believe that all other extravagant figures, or manoeuvres that are in any way capricious (like stall turns against the engine) or those with which you do not have a 100 per cent record, should come early in your sequence, when you are both nice and high, and fairly distant from the crowd. That way, if you do make a hash of it, you have the height and space to recover safely and continue with a curtailed sequence without endangering your life or anybody else’s.

I also believe that an aerobatic display should not be repetitive. My basic plan is to fly just one example of every manoeuvre my little aeroplane can safely accomplish, so I start by making a list. The trick is then to string them together, not only in an eyecatching and pleasing manner, but so that the more tricky ones and the big heightlosers come first. The easier manoeuvres can then come towards the end (by which time I am likely to be getting tired as well as short on height) and because they can be flown without losing too much energy.

Generally, I try to fly two or three figures in front of the crowd when I am high, reducing to a single mid crowd manoeuvre as I get lower.

So, to devise an interesting and entertaining sequence, try making a list of all the aerobatic manoeuvres you can fly really well – perfectly every time. If you have trouble with a particular manoeuvre or figure, remove it from your sequence, and then get good instruction until you can fly it properly. Do not put it back into your proposed sequence until you are sure you can fly it 100 per cent perfectly every time.

When composing routines, I begin with a blank sheet of paper on which I’ve drawn a wind direction, and 20 or so tiny Post-it strips, on each of which I’ve written a figure – loop, slow roll, half Cuban etc. I string these together into possible passes, with initially two, and then later one simple, central manoeuvre between each pair of turnarounds. Ensure the exit speed from the preceding figure or manoeuvre is appropriate to entering the next, or allow space for a dive to increase your speed.

I arrange (and re-arrange, and rearrange) these Post-its on the paper, in the order I think I should fly them, until I have run out of figures or, more usually, have a few crowd-front manoeuvres left, but no more turnarounds. That’s when I have to try and ensure the repeated stall turns and wingovers are separated by as many other figures as possible, so that things don’t become monotonous.

Again, don’t make the sequence too long.

Make 20 figures your maximum. Remember – it is always better to stop after three minutes, or even after just two minutes, leaving the crowd wanting more, than to bore them with five or six minutes of repetitive flying.

As well as running up and down the Aaxis, for variety I think it’s also important to squeeze in something on the B-axis. This of course means having some 90 degree turning figures in your repertoire. Quarterclovers are good for this, and so are quarter up or down vertical rolls with a humptybump at the top.

When I am satisfied I have a pleasing and flyable sequence that is not too repetitive, then I draw it out in Aresti notation on a sequence card to see whether it will stay approximately centred on the card – and thus in front of the crowd. If the picture heads off downwind, I need to start all over again. If it traverses intowind, that’s great. In four minutes a 15kt wind will blow you a full nautical mile downwind, and in a slow aeroplane like mine, it’s important to allow for this in any planned sequence, because motoring into wind between manoeuvres breaks up the rhythm and wastes energy.

Once you have what seems to be a feasible sequence, then walk it through a few times up and down your living room (or your hangar if you prefer). This helps you get a feel for how much space it will occupy, plus enabling you to see where you can lay off drift (or double or treble drift) to compensate for likely on- and off-crowd wind effects. It will also help to fix the sequence in your mind – plus it gives your better half something to laugh about!

Display Practise

Now I climb my aeroplane to a great height (at least 3000ft) and fly part of the sequence – say, the first half, or the first couple of passes – to see how it goes and to find any awkward parts. Then I do the same with the remainder of the sequence, bit by bit until am happy it is all practicable. Then I try flying the whole thing.

After flying the sequence a dozen or more times above 3000ft to establish which will be the tricky figures and combinations, I rewrite it until it becomes flyable and will stay more or less in place over the ground. But it is not easy to confirm your positioning up at 3000ft, so bit by bit I have to bring it down lower to see how my positioning goes.

Do not expect your first ideas to be perfect. I usually find I have to modify a planned sequence several times before I find it is actually feasible, let alone entertaining or visually interesting. Later, after I have a workable sequence, I will undoubtedly make changes and minor adjustments to make it more practical, safer or simpler, or for different venues with angled crowd lines, or those of varying lengths.

Next, when you are satisfied the whole thing is workable, you can string it all together and practise it 50 times, experimenting with maximum and minimum airspeeds for the various figures and combinations.

Then, you can start to bring it lower, 500ft at a time at first. Then, when your lowest height starts coming close to your legal minimum, by 100ft at a time, noting your safe height gates for the top of each figure.

Flying my finalised sequence 40 or 50 times also helps to fix it in my mind. If it does not happen naturally during practise, then I deliberately botch or miss out a figure here and there, to establish a safe alternative sequence afterwards. I also deliberately snap the throttle shut at various awkward points through the routine to practise my replanned recovery from engine failure.

Luckily, in a Fournier like mine, providing you are flying over a runway, it is always certain that you can glide in to a safe landing, although completing some manoeuvres without power can be exciting as your airspeed gets low. Try closing the throttle as you pass through the vertical pulling up into a loop and see what happens! By the time you get close to your minimum height, you should be able to fly this sequence in your sleep, in any possible combination of wind directions, with pre thought-out recoveries for any stuff ups or unexpected problems and with your safety energy (height and speed) gates absolutely fixed in the forefront of your mind.

It is tempting to practise early in the morning or late in the afternoon, when the wind drops to a zephyr and the temperature is low, giving both your engine and your wings their best performance.

However, I believe it is much more important to practise in the worst possible conditions, so that you are used to them, and do not find yourself suddenly confronted with difficult conditions for the first time during a display, when your mind will already be preoccupied.

High temperatures rob your engine of power and your wings of lift. Strong and gusty winds cause you to make lots of small, sharp, draggy control inputs, with occasional inadvertent sideslipping. A steady on- or off-crowd wind requires that you make many control corrections with occasional deliberate sideslips to every manoeuvre. All this robs you of energy.

Worse from the point of view of sapping your aeroplane’s get-up-and-go, is a strong along-crowd wind, which will probably force you to fly at higher than optimum speed into wind from time to time to prevent being blown away. The problem is that, whenever you are flying at more than your aeroplane’s steady maximum speed, you must be descending.

A 30kt wind at 2000ft will force you to fly an extra two miles during a four minute display. Not only will that make you overrun your time slot if you don’t remove at least one pass from your sequence, but it might bring you lower than expected. A gusting wind or thermal turbulence reduces your stall margins, so you have to fly either faster (descending) or more carefully. All this robs your routine of energy, meaningyou will need to start higher than normal and fly more precisely and perhaps more assertively than normal.

For those reasons, whenever possible I try to fly my low level display practises just after lunch, in the worst hot, bumpy, gusty, breezy conditions. That way I know I can deal with them, so I am confident and happy to fly in these conditions when I encounter them. Doing this also gives me a good idea of how much height to add at the beginning my routine if I happen to find the air rough at a particular display.

On the big day, if I do find myself being blown downwind, just once, in the middle of my routine, I keep the throttle wide, gently pitch up 30 or 40 degrees and then pitch down again once the airspeed gets really low. This gives a kind of humped figure that looks to the uninitiated as though it might be some sort of aerobatic manoeuvre.

It takes 10 or 15 seconds and is all flown at below 90kt, so it actually gains a useful 100ft of height as well as getting me a quarter of a mile back to windward.

If you get really low, stop aerobatting and fly a level, balanced 360 degree turn. This takes 15 to 20 seconds, gains me nearly 200ft and only the experts will know it’s not a proper manoeuvre. Believe me, I’ve done it and been congratulated by the display organisers on my “thrilling show”.

From time to time, on the big day the visibility will be limited, robbing you of a clear horizon reference, or there will be a low cloudbase, reducing your start height.

Again, it is a vital to have encountered and practised in these conditions beforehand, and I always have a ‘flat’ routine card in my flying overalls. This features merely a succession of loops and barrel rolls, with at least one full cloverleaf, with gentle wingovers and steep turns as the turnaround manoeuvres at each end of the display line.

I can fly all these without losing any height, even in the most difficult conditions.

Yes, it is much more boring to watch than my usual routine, but it is more interesting than just looking at my rain soaked aeroplane parked on the flight line. And we Fournier fliers have two advantages over the bigger, heavier types. We have a small looping and turning radius, and our low speed enables us to stay within the crowd’s visual range on a murky day, so we can perhaps fly when the unlimited competition machines, warbirds and jets cannot.

But it is essential to practise these ‘flat’ routines, initially in fairly good weather, and then in poorer weather, so you can become used to the myriad unexpected difficulties (like water droplets streaming back over your canopy or spraying on you through the gaps) and the visual illusions of reduced visibility and cloudbase. Then you must stick to your personal limits, rather than guessing whether or not you can fly on a particular occasion. And, believe me, there is a VERY strong temptation to go ahead and fly in a display when the weather is poor but ‘everybody else’ seems to be getting on with the show.

After many years of low performance display flying, my personal limits are now two miles visibility and an 800ft cloudbase, with only light drizzle at the most. Any more precipitation will damage my wooden propeller at airshow rpm. Similarly, I will not take off in more than a 25kt wind or a 12kt crosswind. But I do fly, and more importantly, I do regularly practise in those conditions, so that I will not be out of my depth when I encounter such crud.

And if poor weather prevails at an airshow and I have not practised in those conditions during the past month, still I will not fly. It is disappointing, but much less disappointing than frightening yourself and the crowd, or worse.

I believe you should practise not only in the worst wind, cloud and visibility conditions you might encounter, but bear in mind the possible effect of a low sun. Many displays and airshows run late, and if you’re the last act, you can easily find yourself flying half an hour later than expected. Low sunshine can blind you at an unexpected moment, and a bright, clear upper sky contrasts greatly with gloom down where the hard ground is.

I recently witnessed a nasty moment when a very experienced and able pilot flying a top-notch aeroplane had to display later than planned. The venue was over calm water ringed by tall buildings and by the time he was called in, the sun had set over the hills beyond, although the sky was still bright and his spiralling smoke trail stood out clearly for us spectators.

His third figure was a series of downward rolls, and it was clear soon after he started that things were going wrong. Heading straight down as he was, he must have been confronted by a dark, bottomless pit, with absolutely no surface clues from the flat, black water. Being a professional, he stopped and pulled to the horizon, re-orientated himself and after a momentary pause that only the knowledgeable would have noticed, continued with a rather more subdued display than he had probably intended.

This just goes to show that, however hard you practise and whatever your experience, you can still be caught out, but it behoves us all to prepare as thoroughly as possible.

Go for it, good luck, have fun, and stay safe.

Now you can start thinking about actually bidding for an airshow slot.