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Adrian WillisWritten by Adrian Willis on 17th September 2016

The stall turn is a magnificent aerobatic figure.  It looks graceful and elegant when flown well but is actually very challenging to fly perfectly and the further up the aerobatic ladder you go, the more challenging it becomes with ever more difficult embellishments and energy management issues. The vanilla stall turn has a k factor of 17, making it one of the higher scoring figures, consequently if you aim to win at club or Sports level, mastering this figure is essential.

It takes time to master – the vertical lines must be vertical, counteracting the torque of the engine as you slow down and you must insure the airspeed reaches zero before applying full rudder at the top so that the turn is not ‘bridged’, whilst applying control inputs to counteract the gyroscopic effect of the engine in the turn.

screen-shot-2016-09-15-at-13-13-23

Source: Source: http://www.fai.org/downloads/civa/SC6_Part1

The real secret to success is seeing what is happening and to do this you must look in the right place. Remember that the horizon provides your main reference so you should be devoting your attention to the wing tips so you can see if you are vertical, yawing or rolling. Given practice you will find your entire attention is spent looking and the movement of the controls becomes natural.

 

 

Judging Criteria

 

 

 

How to Fly a Stall Turn

The Stall Turn is a figure that needs to be taught by an experienced instructor. It is quite normal in the early phases of learning for the instructor to have to assist in recovering the situation!

 

Airmanship Points:

For the initial few stall turns a height  of 3,000 to 3,500 feet agl is required so that the instructor can let the student recover if things go astray and yet still have sufficient height to sort things out if the student is unable to.
In addition to all the normal HASSLE checks, make sure cloud base is sufficiently high so that you don’t end up in cloud for the turn!

 

Method:


Aircraft Wing Sight - Vertical Up

Aircraft Wing Sight - Vertically Down

 

 

Common Mistakes:

 

 

The judging criteria has been taken from CIVA Section 6 part 1 PDF from the CIVA website

If you have any question, please comment below and we will answer it as soon as possible. To book an aerobatic flight, contact Adrian on Adrian.Willis@BritishAerobaticAcademy.com or call or message him on 07712864413.

loop-judging-shape-1

Source: http://www.fai.org/aerobatics

In aerobatics, all manoeuvres stem from just a few “prime” figures and the loop is probably the most important of these since it is most prevalent. Even a Stall Turn (Hammer Head for our colonial cousins) incorporates a quarter loop at entry and exit. If you are to succeed in aerobatic competitions, it is therefore essential that you master the prime figures.

 

The Judging Criteria for a Loop:

 

  1. It is a wind corrected figure and must appear round from the judges perspective
  2. It must be on axis
  3. It must be vertical, i.e. not tilted to one side.
  4. The end point should be exactly where the loop started horizontally and vertically.
  5. If loops are flown too close they will be difficult to judge and should be downgraded both in the positioning score but also in the figure score. Similarly if the loop is positioned exactly in front of the judges on the B axis so that the shape cannot be judged, it should be downgraded.
    loop-judging-shape-2

    Source: http://www.fai.org/aerobatics

 

As the loop must appear circular, entry and exit height must be the same and the radius must be constant. All figures start and finish from level flight. Typically judges will hold a pencil to your starting point and estimate the radius of each quarter of the loop. They will confirm you finish at your starting height and position.

 

How to Fly a Loop

There are many different types of loop, we are interested in the competition loop, i.e. on that looks perfectly circular from the judges perspective.

If you were flying a loop at an air display, it would be different to give the best spectacle. You would start and finish from a very low height, but have the ability to cope with an engine failure at any stage. It is a bad idea to be pulling lots of G near the ground so we would pull early and then let the aircraft sink towards the ground to give dramatic effect while preserving a large margin for safety but sacrificing perfect shape.

If you were taking your girl friend for a pleasant aerobatic trip and intending on a longer term relationship, it would be considerate to reduce the G somewhat and also to reduce the negative G at the top. The result would be a “granny loop” or egg shaped loop but also a happier girlfriend. (don’t be one of the many idiots that fly passengers without consideration making them feel sick and putting them off aerobatics for life )

loop-judging-shape-3

Source: http://www.fai.org/aerobatics

The key consideration for a competition loop is to ensure that each quarter loop is the same radius as the first quarter. We will presume the loops to be into wind.

 

Step 1.

Dive for speed (45 degrees). Then come level at your chosen speed, which will vary according to aircraft type. For the Extra a good speed is 150 knots (2.5 x Vs).

 

Step 2.

Fly level for a second or two and note your height and a landmark or line feature straight ahead. Look at your left wing sight and see where it cuts the horizon, then ease the stick back, straight with no aileron, pulling approximately 5 G while continuing to look at the left wing sight and keeping it pegged to the horizon. You are setting the radius of the loop in this first quarter.

 

Step 3

As the speed reduces and you begin the second quarter you must maintain the same radius so smoothly reduce the pressure on the stick. At the top of the loop you should be floating at half of 1 G and approximately 50 knots.

 

Step 4

As you start the third quarter, allow the speed to increase and increase the back pressure. If you pull too hard at the beginning the extra drag will delay the speed increasing.

 

Step 5

loop

Source: http://www.fai.org/aerobatics

As the speed increases increase the back pressure more, remembering to keep looking at the wing tip and keep the sight pegged to the horizon. When you reach level flight, look at the altimeter and confirm you are at your starting height and on your starting heading.

 

Of course, the ball should be perfectly in the middle throughout the loop. It is important to keep looking at the wing tip, so you are not able to use the ball as a reference. In practice you use your body as the ball but also see if the wing tip moves forward or backwards to indicate aircraft yaw. The judges cannot see if your ball is in the middle. On entry when you are fast, you will need a little left rudder (clockwise prop) to balance the power and a little left rudder when you pull to counter the gyro. As the aircraft slows down you will require a little right rudder and then as the aircraft speeds up you will again need a little left rudder. In the Extra the rudder movement required is small and is not a high priority when first starting.

 

Getting a perfect circle is not easy and cannot be properly judged from inside the aircraft without a reasonable amount of experience. In the early days you must fly with an instructor that has significant competition experience and trust what he tells you. Later you will get critique from the ground.

Starting at a high speed and pulling 5 G will make establishing equal radii in all 4 quadrants easier.

 

Effect of Wind

If we imagine a 20 knot wind, down the aerobatic box. A 150 knot entry speed and a 30 knot speed at the top will translate to a 130 knot groundspeed at the bottom and a 50 knot groundspeed at the top. Roughly speaking this is a 2.5 to 1 relationship. If we now contrast this with a 20 knot tailwind, then the entry groundspeed will be 170 knots and the groundspeed at the top will be 10 knots which is roughly a 17 to 1 relationship. To make the loop look round, you will need a much bigger float at the top and a slightly harder pull at the bottom (this will give you perhaps 65 knots at the top so 170 to 45 4 to 1)

Understand where the wind is coming from and adjust the float for it.

 

Common Errors:

 

Conclusion

The well-flown loop is something to take pride in. If you learn properly at the beginning, it will lay the foundations necessary for competition success. Give the British Aerobatic Academy a call on 0771 2864413 or email Adrian at Adrian.Willis@BritishAerobaticAcademy.com and book a lesson while availability is still excellent.

 

The judging criteria has been taken from CIVA Section 6 part 1 PDF from the CIVA website.

 

In previous blog posts we described the judging criteria for the aerobatic competition spin. In this blog I will describe how to fly it and highlight common errors.

Aircraft spin differently according to how you enter the spin. If you are to recover on heading, you need to apply a consistent recovery technique to a consistent spin. To get a consistent spin your entry should be the same every time.

Extra 200 Aerobatic Competition Spin Steps:

  1. From a safe height, smoothly close the throttle, keeping the ball in the middle and raising the nose to maintain level flight.
  2. When the aircraft stalls, promptly apply full rudder followed by a little back stick to prevent the stick inadvertently going forward. Keep the ailerons neutral and count each half turn
  3. At the appropriate point recover by using full throttle and opposite rudder together followed by forward stick. The period before applying forward stick is very short, almost concurrent with the rudder, but not quite.
  4. Looking at the wing tip keep pushing the stick forward until the aircraft is exactly vertical down, using rudder to keep the wings level in yaw.
  5. Execute a quarter loop to come level at the desired speed.

Common Faults:

The key to success is a consistent entry and a consistent recovery. This requires ample practice ideally with somebody who is able to give you good critique from either the ground or inside the cockpit.  If you would like to learn how to spin properly and safely, book a lesson with us and we will gladly teach you.

In Spinning Part 5, we will look at special factors associated with recovery after 1 1/4 and 1 3/4 turns

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What’s your New years resolution? Traditionally the beginning of the New Year calls for strengthening ones resolve to get things done. Aerobatics of course requires commitment and application and therefore needs this resolve. I urge everybody to reorganise their priorities and do it, the only real thing in life is making memories!

I used to take young Airmen and Airwomen sailing as part of the Joint Services Sail Training organisation. Public money was spent doing this because it was deemed to be a valuable character building experience. Timid under confident airmen departed port and transformed, strong and happy characters returned just 2 weeks later. Each person had been mentally and physically stretched and they were all surprised by their own abilities and their confidence grew immeasurably. Pilots and Aerobatics are of course different to airmen and sailing but share some similarities. We are not in the military, you have to be self motivating, but the rewards are enormous.

The key to success is well structured training, with a good trainer. Life is too short and aerobatics too expensive to try to learn everything the hard way. We would love to discuss your aspirations with you and put together some structured training to help you achieve your goals for 2016. Do not be anxious that your goals are too modest or too grand. Also remember we have all sorts of pilots training with us from pre PPL (only 2 weeks ago we had a very good student who was only part way through his PPL course) to pilots who are already ranked in the top few in the world. We also have pilots doing A levels and some in their early 80’s

Make contact, book a course, organise some training and make 2016 a year for achieving goals.

Wishing you all the very best for 2016!

In part 1 I introduced spins and explained the importance of learning to spin. In part 2 I explained the aerodynamics of the spin and the effects of various control inputs. In this blog I will describe the difference between a normal spin and the competition spin and then list the judging criteria. In my next blog (spinning part 4)  I will explain how to fly the competition spin and highlight some common mistakes.

A competition spin is a spin flown according to the judging criteria used in competitions. We will call everything else a normal spin.

If you make an error and end up inadvertently spinning, top of your priorities will be to recover and to do so without losing excessive height. Your immediate action should be to close the throttle and apply opposite rudder and relax back pressure followed by a little forward stick. In the “old days” we recommended that you should let go of the stick completely but some aircraft exhibit “Sticktion”, meaning the stick is sucked to out spin aileron and in these aircraft it is necessary to physically move the stick to the neutral position. The spin will stop almost immediately and as it stops you should neutralise rudder, apply power and ease out of the dive. Thats it, nothing more.  Every aerobatic aircraft must be capable of recovering from a spin provided the C of G is within limits. Rule number 1 is to not fly aerobatics without confirming the weight and balance is within limits. If recovery does not happen you have done something wrong. Check that the ailerons are neutral  and that you really have got full opposite rudder applied and the throttle really is closed.  If that is the case and there is no indication the spin is going to stop, you must have the wrong rudder applied, so change feet, then of course the aircraft must recover.

It is important to understand that you should train with a good instructor before attempting solo spinning, or getting into a situation that could lead to solo spinning.  I have seen many students in the heat of the moment make really basic errors that would have caused them embarrassment solo.  The old adage, “aerobatics has never killed anyone, but hitting the ground often does” is true. Always practice with enough height for things to go wrong and have sufficient height to recover before reaching your minimum height which in the early days should be at least 1,000 feet agl.

In aerobatic competitions we fly in front of a team of “expert” judges. Each judge marks each figure out of 10, deducting one point per 5 degrees of error, and then each score for each figure is multiplied by a k factor representing the difficulty of the figure. A one turn spin has a k factor of 15, so the maximum points that you can score is 150.

Judging rules have evolved to ensure the pilots performance is rated. Wind correction is therefore not required in figures where it would be impossible. So for example, the vertical down line in a competition spin is not wind compensated and therefore the judges are simply looking for the aircraft to be vertical, not its track. We use the Zero Lift Axis (ZLA)of the aircraft to establish this.

Competition Spin judging criteria:

  1. Approach on heading in level flight, no roll or yaw height gain or loss is wrong, lose 1 point per 5 degrees off heading
  2. A clearly visible stall, the nose should drop without the aircraft climbing.
  3. Roll and yaw should begin concurrently and lead immediately to the spin. If it flicks or is forced then a PZ (perception zero) is awarded.
  4. The rotation should stop and the nose should drop to vertical ZLA (Zero Lift Axis) with aircraft on correct heading. Any aileron assistance will cause loss of points 1 point per 5 degrees off heading or off vertical. There must be no perceptible aileron roll to establish the correct final down-line axis.
  5. Rolls on the downline must follow the spin after a short pause they are not centred
  6. Execute a constant radius pull or push to horizontal flight on the correct heading

 

In part 4, we will go through, step by step, how to fly a competition spin. Subscribe to our newsletter to make sure you don’t miss this –

If you want to learn how to spin properly and safely why not book an aerobatic lesson or a spinning and upset recovery course? For more details, email Adrian.Willis@BritishAerobaticAcademy.com or sms/telephone 07712864413.

 

When an aircraft wing “stalls”, the airflow detaches from the wing and reduces lift and increases drag. The stall is the name given to this condition which is caused by the angle of attack (alpha) being excessive or going beyond critical. The speed this occurs at varies according to various factors including G, weight, power setting, air density etc. and is largely irrelevant from the pilots point of view as it is the critical alpha that is relevant, not the speed. It is convenient to know the approximate speed of reaching critical alpha at a certain configuration. In terms of aerobatics this will be a power off, 1 G condition at normal weight and normal height, clean stall. We know also that with power on, critical alpha will be at a lower speed, all other factors being equal. In the Extra 200, the aircraft we teach aerobatics and spinning in at the British Aerobatic Academy and what most of our tutorial will be based on, this is approximately 60kts.

If full left rudder is applied when the aircraft is stalled the yaw will cause the left wing to move backwards and the right wing forwards, the local airspeed difference will cause the right wing to rise and the left wing to drop and as the rudder is held in, this will continue. If the rudder were to be neutralised, at this very early stage, the spin would stop. This early stage where auto rotation has not become self-sustaining is known as the incipient spin.

With the rudder held in, the rolling and yawing movement will cause the left wing to have a greater angle of attack than the right, i.e. “be more stalled” and this will cause more drag and less lift which will cause the autorotation to be self-sustaining. This is known as a fully developed spin and occurs after a different number of rotations in different aircraft. It also occurs after a different number of rotations depending on how the spin is entered. In the Extra for example, if you enter the spin from significantly below the 1 G stalling speed, say 40 knots, it will take a long time to become fully developed and will be very slow to start spinning at all. This is because both wings will be heavily stalled and when rudder is applied, unless it is applied very vigorously, the lift difference between wings is not great so the aircraft just sinks with very little wing rise and therefore the alpha on each wing is not very different so autorotation is slow to develop.

From this description it is important to understand that the myth that if you let go of all the controls during a spin, it will recover itself, is wrong. This is only true if the spin is insipient and cannot be true, by definition, in a fully developed spin. What is certainly true in many aircraft is that the insipient stage can last a long time and during this period if you remove all control inputs, the aircraft will recover.

It is important to understand the effect of aileron. If you are spinning to the left and you apply right aileron, it will slow down recovery and increase the rate of rotation a little. This is because right aileron increases the angle of attack of the left wing and so reduces lift and increases drag which creates a stronger auto-rotative force. The effects of aileron vary according to aircraft type. In a Sukhoi 29 for example, full out spin aileron will prevent recovery. In an Extra it will significantly slow it down. The bottom line is to resist the natural instinct to use out spin aileron and consciously check the stick is neutral during recovery. The engine and propeller also have a big effect on the characteristics of a spin. If you are flying a lycoming powered aircraft, with a propeller that rotates to the right as seen from the pilots seat, then the gyroscopic force of propeller will lift the nose in a left hand spin. The amount of this force will vary according to the power setting. Therefore in all cases you must ensure the throttle is fully aft when entering a spin.

Later on I will write about flat spins, this is when we will push the throttle forward and thus flattening the spin, and inverted spin, this is where the aircraft enters inverted. It is the same as an erect spin except you are upside down and consequently the roll is opposite to yaw.  – subscribe to our newsletter to make sure you don’ t miss this!

Spinning is a complicated topic and is misunderstood by many, if you have any questions about spinning, please write a comment below and I will answer it as quickly as I can. If you want to learn how to spin properly, why not book a spinning and upset recovery course – or go the full hog and sign up for the Basic Aeros course?

During your flying training, you may have been lucky enough to experience a spin. Unfortunately it is no-longer a syllabus requirement for either the PPL or CPL course. So quite probably you will only have been taught how to avoid spin situations. Undoubtedly this absence of experience will have contributed to the mystique of the spin.

I remember very clearly a good friend talking to me one morning about his desire for some proper spin training.  I had to take my student to the Little Gransden Beginners day, when I arrived, the airfield owner telephoned me to say that there had been an accident and this same person had an engine failure and spun at low level into the ground. If only we had done a single trip together he would be alive today! Spin training would undoubtedly have made him much more aware of pre spin conditions and certainly would have instilled the reactions necessary to avoid entering  or at the very worst would have provided the tools necessary to smartly recover from a wing drop.  I certainly believe that it was a bad decision to remove spinning from the PPL syllabus. Certainly there is a growing list of Commercial Airline accidents and “occurances” that have led many of the worlds aviation authorities, including EASA to reach the same conclusion and from 2018 onwards, all newly qualified commercial pilots will be required to have undergone upset prevention and recovery training. We recommend every pilot completes our Spinning and Upset Recovery Course At the end of this course you will be fully  equipped to avoid spins and recover from them with out delay at every stage and will understand them fully. The course also covers many other flight upset situations and you will end up a much better pilot and will certainly thoroughly enjoy the learning experience.

Having started with a morbid account that reinforces the need for spin training, it is reassuring to remember that spinning does not kill people, but hitting the ground does! We make very sure this does not happen.  We operate to a base height of 1,000 feet. This means that we aim to be fully recovered from any “botched up” manoeuvre by 1,000 feet.  In actual fact, since recovery from botched up manoeuvres is key to the learning process, I would allow enough height for the student to be able to recover, get this wrong and still have sufficient height to recover myself before passing 1,000 ft.  Of course part of the aim of spin training is to grow justifiable confidence, so we measure the height at spin entry and at spin exit and we count each half turn and recover on heading. After many repetitions we can be absolutely certain and confident of being able to precisely control every aspect of the spin.

It is perfectly normal to have a degree of anxiety prior to spinning, indeed it would be unhealthy not to have a strong self preservation instinct. Certainly in aerobatic circles almost everybody will admit to being anxious before their first solo spin. Indeed overcoming these hurdles is one of the joys of the sport but is reassuring to know that everybody who has made the journey has felt the same way.  The moto of No 1 Parachute Training School is “Knowledge Dispels Fear”. This is certainly true and to overcome a fear of spinning requires proper training in a professional environment and lots of practice.

This post is part of a 7 part series on spinning. To make sure that you get all of the
posts, subscribe to our newsletter where you will be notified when the next posts are released.

We have had a most magnificent season with students attending courses from:
Japan, Switzerland, Qatar, Russia, Poland, Italy, Greece, Scotland, England, Lithuania, Hungry, Hong Kong, China, Egypt and Spain.

We have managed approximately 1,000 flying hours and have had approximately 20 students enter various competitions with surprising success.