Ever wanted to get into or improve your aerobatics?

[Terence Moore]

Just a quircky notion of mine.

Draw it out as follows:- project your line of sight to approx 30 metres high at a distance of 150 metres. Then draw a line perpendicular upwards from this & compare it's verticality to the ground.........its leaning over past the vertical!!!!

That's perhaps an exageration, but illustrates the difference between the perception and reality of a vertical line some distance away from the pilot/judge/examiner.

[Peter Jenkins]

For what it's worth, my view is that since the pilot and judges are within 10 mtrs of each other if a line appears vertical to one it will appear vertical to the other. Whether it is truly vertical would be very difficult to determine since there is no one directly under the aircraft measuring its true track. In any event you are supposed to compensate for any side/head/tail wind by "leaning" the aircraft in the appropriate direction to establish what appears to the judges to be the true vertical line of the aircraft's C of G. That inevitably makes it more difficult to judge true vertical.

I am not aware of guidance to F3A judges that they should be looking for a vertical that leans past the vertical in any of the judging criteria. There is no apparatus provided to judges to measure vertical lines (or 45 degree lines for that matter) even at international competitions so it would be difficult for a truly objective view to be obtained especially since the vertical line rarely exceeds around 5-6 secs. It is easier to spot a downline that differs from an upline in its geometry.

I do know that if you perform a centre based stall turn, it can appear as if the model is coming towards you on the vertical climb especially if the climb is continued towards the top of the box - this is around 950 ft when flown at 150 mtrs out. I think, but I'm not sure, this might be due to perspective issues. Mind you, it might just be my poor flying!

[Terence Moore]

Sorry but i was relating this to pilots progressing towards the "B" Cert. I sometimes fond they have difficulty with the vertical line, in that the model can drop onto it's back, and in these circumstances I draw out the geometry to illustrate my point.

This was not meant to be read in relation to competitive F3A flying.

In full size aerobatic competitions however, sighting aids are fixed to the aircraft's wingtips to assist with true 45 degree and vertical lines relative to the horizon, and in these comps the judges are similarly located aligned with the centre of the box, so their perception probably the same.

[Peter Jenkins]

Hi Terence, I've always found that the cure for either dropping on its back or front is to maintain sufficient throttle to allow the aircraft to decelerate and keep adequate control with rudder and elevator. When you are wind correcting for a stall turn at the down wind end of the circuit then clearly you need to tilt the vertical into the wind otherwise the model will get blown downwind and vice versa. Could this be demonstrated with a slightly off centre stall turn so that candidates can see the line more clearly than when at the bottom end of the circuit?

With full size aerobatics, my understanding is that the aircraft has to be in either the true vertical or 45 degree line and, as you say, the aircraft carry a contraption on the wingtips which allow the pilot to align the sighting mark with the horizon. I believe that there is no allowance made for wind in such a situation which is different from the model aircraft situation. I don't know why this is the case since both are judged from a static position at the centre line of but outside the aerobatic box.

["L"Plate]

In my day (a long time ago), for the full size you had to fly the line vertical as best you could compensating for the wing, the tip frames gave you a reference but you still tilted slightly into wing until you were close to the turn itself then you made it true vertical. Still the judges saw it the same way as an RC pilot, judge / examiner now. I was told that for extreme verticals it appeared the aircraft was curving away from the viewer, but to my eye it always looked right.

I think most of the time that I flop forward or backward with a model on a stall turn is when either I allow it to slow too much without enough throttle to give prop wash or it is not enough and has a CofG too far forward.

I think an examiner would have to be very picky to fail a candidate for the vertical for the amount of effect that the perspective would have, this is not precision aerobatics, it is about being in safe and correct control. So the aircraft going up at close to vertical (say between 87 and 93 deg possibly more on a windy day) a proper stall (not a wing over) and then returning down the same line / very close to the same line; to me would show good control, although not perfect (but then I am not an examiner so will bow down to you and Peter).

[Peter Jenkins]

My understanding is that one looks for reasonable accuracy but not perfection. It is more important that the whole flight is conducted safely, the pilot demonstrates they have full control over the flight and shows reasonable accuracy although the definition of accuracy is always open to interpretation. Hence the use of examiner workshops to enable groups of examiners to agree on what is reasonable. The B is not about testing your aerobatic capability but rather using aerobatic manoeuvres to see if the candidate can maintain a reasonable degree of accuracy while flying them and while flying in between them. Positioning between manoeuvres acts as an additional element for the examiner to use if the candidate looks borderline on the main manoeuvres - something to remember and to do something about!

[Willyuk]

Hooray! Thanks Peter, all this discussion of vertical lines and timing of slow rolls was beginning to make me doubt I could EVER achieve a sufficient standard. I would like to be that good, but that needs practise and most of us have only so many hours we can devote to flying. I see the B test as a means to improve my accuracy, awareness and safety without it being a hurdle too high to hope for. I need to feel it is within my capabilities after a reasonable amount of dedicated practise. Now where is that weather window?

["L"Plate]

Well said Willyuk, too much challenging the good advice Peter is giving.

[Peter Jenkins]

OK, before we leave the stall turn, there is something I wanted to pass on. When I was trying to use rudder in a slow roll on my Wot 4, I found that the secondary effect of rudder (roll) was so strong that it made using the rudder in the slow roll almost impossible. So, after having a careful think about the problem I set up a mix with rudder as master and aileron as slave with the ailerons being set to oppose the rudder induced roll. That means that when flying straight and level you should be able to use rudder to carry out a flat turn with minimal use of aileron to keep the wings level. At the top of the stall turn, when you apply rudder, you again get a rolling effect but the aileron mix helps to reduce this effect and avoids you having to put in opposite aileron to the rudder to prevent the aircraft rolling as it yaws over the top.

With a specialist aerobatic model, you don't tend to get this problem but with less well behaved ones you will find that implementing this mix will make your life easier.

[Peter Jenkins]

Remember, that after completing the stall you must fly past the pilot's position before the manoueuvre is counted as being completed. So, having pulled level after the stall turn don't be in too much of a hurry to start positioning for your next manoeuvre which will be the 3 turn spin. Once you have come past yourself you need to fly a climbing circuit that positions the model in front of you but much further out than the standard line (look for a spot around 60 deg to the horizontal which will put you in the right place. You should have completed your climb to enable you to fly your model in to position for the spin in level flight. Climbing into a spin at a 30 deg angle will not do. You need to be flying straight and level for some distance before you get to spinning point so that you can slow the aircraft down smoothly and accurately to allow a spin to be started dead in front of you. Don't worry if its not bang in front but if you are miles out expect to be failed or asked to re-do the manoeuvre.

The spin is described in the guide. The wording is quite interesting in that it says that this is the only way to enter a spin. I beg to differ and quote the way that spinning is described in F3A parlance. The guide requires the aircraft to be slowed down to just above stalling speed so that the application of rudder will then stall the wing on the side to which the rudder has been applied. This begs the question of how you are to judge this speed when you are unsure of the prevailing wind speed at the height the aircraft is being flown so that you can gauge the critical airspeed. After all, if you have a flick entry your spin is unacceptable and, in my view, you have a high likelihood of having a flick entry using this procedure.

Far better to use the process that is used in aerobatic competition. That is slow the aircraft down until it stalls and as soon as you see the nose drop apply rudder. Provided that you have the CG in the correct place and there is sufficient up elevator, the aircraft will then enter a spin without flicking and on every occasion that you need it.

So, CG position is vitally important in this. A forward CG and you might find that there is insufficient up elevator movement to cause a stall in the first place. The aircraft will just keep flying at a very slow speed. The first thing to then try is to increase the up elevator movement and see if that results in a stall. In that respect, you should be aiming to fly the aircraft to the point at which you have to spin, the centre line of your flying area and sufficiently far out so it is not going to be overhead you at the end of the spin. You close the throttle progressively so that the aircraft slows down smoothly and you have enough control over it to ensure that it keeps flying slowly until it is almost at the spinning point. At that point, fully retard the throttle and then, while continuing to fly level or a very slight climb, keep easing the elevator back until the aircraft drops its nose - it's telling you that it has stalled - at which point apply full aft elevator and rudder in the desired direction.

Which is the desired direction? Go and approach the stall in the way i have described above. Keep the wings level and the model on a constant heading. Carry out about 10 stalls and watch carefully, you can ask a colleague to watch as well, which wing is the one that consistently drops. If it's the right wing then spin to the right and vice versa. If it doesn't favour either wing so it can sometimes drop the left or the right wing then you will need to watch carefully to see which wing drops at the stall and spin in that direction. Don't let an incipient spin develop to the left and then apply right rudder as the spin entry will look very messy and the examiner would be perfectly entitled to ask you to repeat the manoeuvre.

If having started to spin the aircraft comes out of the spin and you get a spiral dive, then you need either to increase the up elevator movement or to move the CG a little bit further back. You will know when you have moved the CG enough as the aircraft will then remain in the spin till you either apply spin recovery actions or just centre the controls.

When to apply spin recovery will depend on the model you are flying. The best way to find out how long it takes the aircraft to recover from the spin is to perform the full 3 turns and then either centralise the rudder and elevator (all that I've ever needed on sport/aerobatic aircraft) or apply full opposite rudder and move the elevator progressively forward till the spin stops (possibly a situation with some, particularly scale, aircraft). See where the model comes out of the spin and then next time begin the spin recovery by that amount before the 3rd turn. On my Wot 4, I have to centralise the rudder and elevator 3/4 turn before the exit heading whereas my 2 mtr F3A will recover in 1/8 turn. I have yet to need to use aileron to hold a sport/aerobatic aircraft in a spin but yours might require this but remember not to apply aileron (in the same direction as the rudder) until the spin has commenced as having a wing tip up before the aircraft stalls is also a fail for the spin. That's another reason for not following the current guidance document.

At one of the examiner's workshops we decided this change on spin entry should be included in future guides and we wrote into the ASRC asking for that change to be made. I shall see what the 2015 guide says in due course!

[Peter Jenkins]

Some final points on spin recovery. Once the aircraft has stopped rotating, allow it to accelerate downwards so that you can see a straight line from the end if the spin until you begin the recovery from the dive. You are not required to show a vertical dive, as in aerobatics, but equally, don't haul in full up elevator immediately the spin stops. The key points are to allow the aircraft to accelerate from stalling speed to a reasonable speed and then perform a gentle pull out. When the model reaches about 45 deg angle smoothly open the throttle to your cruising speed setting and fly the aircraft straight and level for a short period.

The next manoeuvre is to carry out an approach and overshoot. So, the first thing you need to do is to join the circuit on the downwind leg. If you have been blown either a long way into the circuit or a long way out of the circuit then always turn in the direction that will get you closest to the downwind leg position. The requirement is for a rectangular approach and overshoot from below 10 ft. You should always assume that you might have to land off this approach so you should fly it accordingly. The guidance notes are quite clear on this point. That way, you should not fall foul of a low fastish pass which is not what is required. The examiner will be expecting to see you check that the landing area is clear by turning your head to visually check. Don't forget to call LANDING and OVERSHOOT. I cannot overemphasise the importance of checking for other aircraft in the circuit and that the runway is clear. Yes, it means you have to take your eyes off the model while you do this. If you cannot, then you are not yet ready for the Test and need to practise a bit more.

As you call OVERSHOOT, advance the throttle smoothly to climb power and establish a smooth climb at the same angle as your original take off. You may wish to restrict the height you climb to so that you do not have to lose a lot of height for the next manoeuvre. Do remember that you must fly the aircraft on the same heading until you reach the upwind end of the circuit pattern you have previously established.

At that point, carry out a P turn and reduce height to not more than 40 ft to join the downwind leg of a rectangular circuit in the opposite direction to the normal circuit. Making sure you fly to the top end of the circuit will give you time to get the height right in the P turn or shortly after rolling out of it so that the aircraft is nicely set to start the reverse circuit well before it comes past your/the examiner’s position. This manoeuvre requires great concentration on maintaining the required height of not more than 40 ft. This is where not having too much elevator movement is a boon as you will be able to make small adjustments in attitude without having the aircraft betray every elevator movement. Make sure you fly no more than 45 deg banked turns, and fly the upwind leg parallel to the downwind leg. The manoeuvre is complete after you have flown past your position once again.

["L"Plate]

I have nor seen it written but I feel it is good practice, that if you are reversing the direction of a circuit that you call it so others know. Whether this is expected during the test I am not sure but if other pilots are flying at the same time as you this should help avoid the head on crunch, also carry out a visual before changing direction.

Edited By "L"Plate on 19/11/2014 14:47:10

[Ultymate]

I appreciate we're discussing "B" test procedures here but one of my pet hates is visiting clubs where rules stipulate "one way only" circuits. For a start off turnaround aerobatics are impossible under such circumstances and in my experience flying this way always results in "left hand Pete" or "right hand Paul" syndrome whereby the local pilots get their one way circuits so habitually engrained that when asked or forced to fly the none "usual" way mayhem ensues. Far better in my opinion to develop the skill of being aware of their and others models and using height separation as and when necessary. I hope this doesn't offend but I've visited many clubs and venues whilst competing and almost always find the standard of flying and indeed safety to be lower where said club insists on one way circuits. I do appreciate that at show venues whoever is running the flight line ie flight line steward may deem it necessary to fly one way circuits in the interest of public safety JMHO.

[Peter Jenkins]

Dead right L Plate. Wrap on my knuckles for forgetting to mention that. Thanks for flagging it up. The same goes for all the occasions that you reverse or return to circuit direction. These are: the second set of rolls, difficult to call reversing circuit when on the downline of the stall turn, but a valid call(!) as well as the low level reverse circuit and return to the normal circuit direction. You should include all of these refinements in your practice so that, even if you have the sky to yourself on your test, you still call so that everyone knows what's going on - not least the examiner who will then not be able to accuse you of not checking the circuit before calling change of direction, landing etc.

[Peter Jenkins]

Ultymate, I think what you are reflecting is the fact that many pilots seem to be quite happy, once they have got their A Cert (although in some Clubs even that can be a rarity) to just fly for fun and never to try anything new lest they prang their aeroplane. I think that could be down to the the lack of encouragement on the part of some instructors and examiners to persuade pilots to have a go at something a bit different. I very much hope that this thread might have got some pilots thinking seriously about having a go at the B and then dipping their toe into the world of competitive aerobatics. It's not too difficult a challenge and something that almost every pilot could aspire to provided they adopt a disciplined approach to their trimming and flying. At the end of the day, it all comes down to practice.

If you feel uncomfortable flying a RH circuit then fly them when ever you can to get better at them. Never allow yourself to end up being handed so that you only fly rolls to the left for example.

Good point and well brought out.

[Peter Jenkins]

Right, back to the B! Once you have completed the low level circuit and have flown past your position wait until the aircraft is approaching the downwind end of the circuit and then carry out a climbing P turn to bring you back past yourself but at standard height and line this time. Don’t forget to call “reversing circuit”. You are now about to enter the last manoeuvre with is to fly a rectangular circuit and land (wheels to touch within a pre-designated 30 mtr boundary).

Remember to fly smoothly banked turns of no more than 45 deg, check the landing area and circuit is clear before calling LANDING and make sure that your circuit is as good as you can get it as the last impression you want your examiner to have is a good one! Don’t rush this manoeuvre and make sure that you carry out a fully held off landing so that the danger of bouncing is all but eliminated.

Once the aircraft is safely on the ground, don’t ruin it by doing something silly like taxying into the pits! Taxy so that you are clear of the runway and to a safe position where you can cut the engine. Remember, if you are flying an electric aircraft you must treat it as live until you have disarmed the motor. If you have a helper who will recover the aircraft to the pits, make sure you have briefed them only to act on your instructions. They should only switch off the Rx for example if you ask them to do that. Your helper is just that – your helper – not someone involved in the test.

Now you can take a deep breath and then continue with the post flight checks as set out in the BMFA Handbook.

At the end of your Post Flight Checks, if all has been well so far, then the Examiner will set about asking you “a minimum of eight questions on safety matters, based on the BMFA Safety Codes for General Flying, Model Flying Displays and local flying rules”.

Remember that you have to pass both parts of the test to gain your B. It may be that a slightly borderline flying test will be OK if you do really well on the examination questions or vice versa but it will be up to the Examiner to make that call on the day. You are not expected to answer the questions parrot fashion quoting all the necessary detail e.g. it is not necessary to remember the precise number of the paras in the ANO but rather what they mean in practice and how you would act in order to remain within the law.

Remember that if you do not pass, you are allowed another attempt that day. It may be useful, if the Examiner has the time, to ask for a coaching session with them before you attempt your next official attempt.

However, if all has gone according to plan, your Examiner will then tell you that you have passed and then fill out the relevant B Test Certificate for which you will need to know your BMFA number and the Club’s BMFA number (if the examiner is not from your Club i.e. is an Area Chief Examiner).

It’s important to remember that now you are a B pilot, you need to set an example to others in your Club by your adherence to safety procedures and accuracy in flying. Do look to keep your B skills polished as that is one very powerful way in which you will reduce the chance of crashing your aircraft. While a B Certificate will be required if you are to fly in front of the public that is not the main reason for having a B. Indeed, it would be a very foolish Display Director who would accept you as a display pilot on your first display without first seeing you fly. Remember that at the Farnborough International Air Show, the world’s top military and civil display pilots have to have their displays cleared by the Display Director before they are allowed to fly in the Farnborough Display. So, don’t think that with your freshly minted B Certificate that gives you the unfettered right to fly in displays without any let or hindrance! Mind you, if you thought that then you couldn’t have read the BMFA code on the conduct of model flying displays very thoroughly!

[Martyn K]

Hi Peter

Been a bit quiet recently, but isn't there a requirement to do an overshoot?

Martyn

["L"Plate]

Martyn, About seven post above

[Martyn K]

Thanks 'L' plate - dunno how I missed that.

[Max50]

I know it would be good practice to call " reverse circuit ", but in our club that allows reverse circuit flying; with a max of 5 people flying, i think we would sound like a load of chickens, " reverse circuit " , " reverse circuit " , " reverse circuit " all the time , when we are flying during summer. . Always fly a reverse circuit, to stop getting circuit handed. It doesn't seem a hinderance at the club. I didn't see for any reverse circuit calls in the " B " test or the BMFA handbook.

Maybe i haven't been looking.

[Masher]

At our club we set the circuit direction according to the wind direction on the day. Also we move the pits to the opposite side of the field in winter to avoid the low sun and because we have to walk across the wet field. It is good practice to change like this because it is surprising how "awkward" it feels when something changes.

I have also noticed that whichever direction/attitude we are in, the trees still manage to jump out and grab you!

[Peter Jenkins]

Hi Max 50, I would put this down to good "airmanship". If I am flying and someone wants to fly a manoeuvre in the middle of the field it's quite helpful to hear "loop in the centre" so I am alerted to what's happening and don't just barrel through the middle and get T boned by a model entering a loop. One can have too many rules and then leave out a really useful call like "reverse low level circuit" so I look on these things as what would I find useful to hear when I'm flying. Some folks seem to get chatty about all manner of things when they are flying which I find very off putting while I'm trying to concentrate on my flying. Each to his own unless the chatting becomes distracting. I can remember asking someone not to talk to me when I was flying as I couldn't fly my schedule and indulge in general chit chat as my little brain can't cope with both!

Airmanship is a difficult thing to define but one way of looking at it is staying one step ahead of the game so that you are not caught out by the unexpected which quite often turns out to be not so unexpected when viewed in the cold light of day!

[Peter Jenkins]

Masher - have you tried aiming to hit the trees? I find it darn difficult to hit stuff you aim for whereas stuff you don't aim for is dead easy to hit!

[Max50]

In the examiners workshops are you told to listen out for reverse circuit or/and manoeuvre calls or is this an option of the candidate over the normal take off/landing/overshoot calls. Normally when taking a test at our club they allow the candidate to fly alone, and everyone else watches.

[Peter Jenkins]

Hi Max50, your comment falls into the ambigous area for the test and is one that I would like to see either called for or advised against - one or the other. At the moment, I've heard some examiners say they want the candidate to call start and finish of the manoeuvre and others who say they will call the next manoeuvre. I hope this will not take too long on which to get clarification. In the mean time, you need to check with your examiner what are his/her expectations and then follow those.