Ever wanted to get into or improve your aerobatics?

[Geoff Reynolds]

Peter, I'd like you to complete your 'B' tutorial please, be it on this page or another designated stream.

Without a 'B' I'm never going to improve or progress from a basic club flyer, neither will there be any incentive to improve and strive for something better because there would be nothing to aim for.

It would be a shame to drop this thread, so please continue to the end.

Geoff

[Willyuk]

I will second that. Carry on the good work.

[Steve Colman]

Yes, please do continue Peter. This is a valued and must read thread for me.

Steve.

[Max50]

+1 Peter. Please continue with the 'B' thanks. There needs to be more encouragement for people to go for the 'B' and this thread is doing it for me . In our club; people are quite happy to pass their 'A' and just fly; which is OK because that's what we take up this hobby for; the enjoyment of flying and the good company; but that means less of a pool of flyers for your aerobatic and other competitions, including IMAC and Scale i assume.

I wanted to try and pass my 'B' to allow me to fly over 7kg models ( not for public flying side ), but this thread has got me more and more interested in the aerobatic flying side of the hobby.

So keep up the good work.

[Peter Jenkins]

OK guys, I've got the message so on with the B.

OK, so we’ve navigated the first set of rolls and we need to come back and do the second set but these will be in the opposite direction. If you always roll away from yourself then you are guaranteed to have done the rolls in different directions without needing to think about which way you rolled on your first set of rolls.

It is especially important when there is a strongish wind blowing to go sufficient far upwind before your carry out your P or procedure turn to come back for the second set of rolls as your ground speed will be much higher for the downwind rolls. That means less time to set yourself up and you have to start rolling much earlier than for the into wind rolls so that your rolls are properly centred.

I often see pilots who seem unable to bring themselves to follow the rule that manoeuvres like the loop, bunt and 2 rolls have to be centred. This doesn’t mean you have to be exactly in the centre but you must make a good effort to do so. It is just as easy to fly badly as to fly well so you might as well use your energy to fly well and then it will become a habit which you just don’t even think about.

If you are coping with a cross wind, the good news is that cross winds don’t cause you a problem when you roll as they do when you loop. Provided you’ve judged the heading for the model into the crosswind correctly then it is your application of down and up elevator which will drag you off line and not the cross wind. Of course, if you have not set an appropriate course and are getting blown off track before you even start the rolls don’t bother rolling but sort out the correct angle to fly into the cross wind so that your ground track is parallel to the runway or the datum that you are using.

[Willyuk]

Why this thing about rolling away from yourself? Surely in a roll the aircraft spends as much time facing in one direction as any other. It does 360 degrees. Is it because it's more likely to go wrong in the first half of the roll ( not with me!). I don't have an issue with doing it that way but what is the reason and why is it preferable?

[Peter Jenkins]

That is a good question Willyuk. Basically, it was felt that there was a higher risk associated with an initial roll towards the "crowd line" and so the strong recommendation is for the initial roll to be in the direction away from the crowd line. It is a debateable point but since you have to roll both ways anyway it doesn't make any difference to the level of difficulty or skill required.

[David Hardaker]

Peter

Willyuk has a point regarding roll direction. The Examiners guide doesn't say that rolls shall be away from the observers. It's only stall turns that have to be carried out away from the observers.

It's the "rule within a rule" situation that is irritating ! As said before the A and B achievement levels are about awareness, airmanship, preparation, planning, safety and flying.

Not necessarily in that order.

David

[Willyuk]

Well, I have had this discussion about rules with a few examiners and interpretation is all, I think any examiner would be happy to discuss what he is looking for prior to the test when such issues could be clarified. I don't think these should be "failure" rules but the examiner could discuss such matters as best practise. its a similar situation with the range check, it's good practise to carry it out before a session, though not in the written rules. As Peter says this thread should be aimed at helping people like me who want to do the test, so every bit of advice is valuable. Also I would assume that by the time one is ready for the test a roll in either direction should be within ones capabilities. As a final point, the examiners can ask for a manoeuvre to be repeated, so that would allow one to demonstrate the capability to roll away from the crowd line. I

I bet the BMFA never expected this much debate!

[Peter Jenkins]

David and Willyuk - as part of the first examiners workshop in the East Anglia Area, we have already submitted some suggestions for clarification to the A and B schedule descriptions to the Achievement Scheme Review Committee. Yes there is one of those! I am hoping that as we find more of these areas that are open to "interpretation" that we get them discussed in this Committee with a view to avoiding the need for "interpretation". However, in the mean time, I'm trying to flag up the issues as they arise so that at the very least candidates can be aware of the need to have a discussion with their examiner(s) before their flight to resolve these areas to their mutual satisfaction.

I hope this need for clarification will go away as the issues are dealt with by the ASRC but we shall have to wait and see.

Incidentally, the ASRC now re-publish the Guides for all the Achievement Scheme tests on an annual basis. I'm not sure of the timetable but it would be wise to check the BMFA website containing these downloadable documents in late Jan 2015.

Peter

[Peter Jenkins]

OK, sorry about the gap in posting the next bit which will be the stall turn.

The next manoeuvre after the 2^nd of the two rolls, is the Stall Turn. The guide calls for

• “the model to be flown past the pilot for about 100 yards before the manoeuvre is performed, returning past the pilot at standard height and line when the manoeuvre is completed”.
• “the direction of the stall turn to be performed away from the flight line i.e. if the wind is from the right, the model is flown past the pilot from left to right, pulled up and stall turned to the LEFT”
• “the ‘vertical climb and dive’ should be near vertical” – in other words, corrected for the wind speed and direction
• “the model should not ‘fly’ over the top in a semi-circle…….a recognisable stall turn that is not a chandelle or a wing over.

Other points to bear in mind:

• Entry and exit heights to be substantially the same
• Allow sufficient time in the vertical climb to stabilise the aircraft path and decelerate but don’t make your life hard by going up a loooong way.
• Never close the throttle before you apply rudder to start the turn – that’s a sure fire way to cause the model to flop forwards or backwards or do a tail slide! More on this later.
• Allow the model to accelerate downwards on the same(ish) path it followed on the way up and perform the pull out to the same(ish) diameter ¼ loop you used to enter.
• Don’t snatch the model level as soon as the stall turn is completed. You stand a good chance of causing the model to stall again and possibly spin. You may be fine with a trainer type of aircraft but if you try this with a high wing loading sharply tapered wing type you’ll almost certainly stall and spin. Don’t get into bad habits that will cost you a model later on in your modelling life. It looks better as well!

You can go straight into the stall turn at the end of the 2^nd set of two rolls but if you are a long way down wind it will be best to reposition by flying another circuit. Remember this will be in the reverse direction to your normal circuit direction. Again, this is something to discuss with your examiner before hand.

[Willyuk]

Hi Peter,

can you clarify a couple of points please. On the stall turn can I assume that it is NOT a requirement to completely close the throttle at any point?

when I attended the training day, it was expected that the candidate would announce each manoeuvre and then say manoeuvre complete when finished. Also it sort of seemed that the examiner was "calling" the manoeuvres, i.e "next an outside loop"

I would find it a help, and perhaps others would too, if when you have completed your technical explanations you could run through how a typical test might go. I know there is a lot in the guide but a view from a current examiner of how it unfolds and what might be said to the candidate during the test might allay some fears and reduce nerves.

if only this damned wind would change direction I could do some practise!

thanks

[Ultymate]

I must admit that I may not be fully up to speed on the latest requirements the BMFA stipulate for the "B" test but I was under the belief that said manoeuvres were not needed to be flown as a "schedule" as such, Another point I'd beg to differ with is that if I do not close the throttle at the top of my upline on a stall turn then I'm almost certainly going to fly a wingover.

Willyuk you should be practising whatever the wind direcion

[Willyuk]

Ultymate, in general I agree but the problem with the wind is that, from the south, it has to come over the top of some tall trees that are close to and parallel with the landing strip. I am advised that the turbulence caused by said trees makes using the strip with a strong southerly wind is extremely inadvisable. I have always heeded this advice so have no direct experience of how bad it is at that particular site. I am not worried about cross wind landings ( well a bit worried but I try my best) but when really good pilots advise me to keep away with these conditions, I listen.

Lets hope for a change of direction soon!

[Ultymate]

Understood I know local scenarios can affect play

[Peter Jenkins]

OK, since two people have raised the issue, let me explain a bit more about the use of throttle in a stall turn at the moment critique!

The point at which you apply rudder to turn the aircraft is the point at which the aircraft is momentarily stationary. At that point, if the engine is idling, there is precious little airflow over the elevator and rudder to control the aircraft so it is pot luck which way it decides to go. When you pull up into the climb you apply a bit more power than for straight and level flight (how much depends on the power to weight ratio of your aircraft) and then, as you approach the height you have selected for your stall turn, retard the throttle, let’s say to ¼, and wait for the aircraft to stop while keeping it travelling vertically upwards. Immediately it stops you apply full rudder in the direction desired and, as the nose drops through the 90 deg mark, close the throttle.

Notice I said as the aircraft is travelling vertically upwards and not pointing vertically upwards. If you are compensating for wind you will have some rudder applied and some elevator applied as the aircraft may well not be pointing vertically upwards. It’s not as difficult as it sounds by the way but there are some techniques that can make it easier still! So, that’s another reason for keeping some level of power on to allow you to control the aircraft up to the moment of the actual stall turn. So, if the wind is blowing you away from the “crowd line” you will have to yaw the aircraft in the direction of the said line but the stall turn will have to be carried out turning away from the crowd. Another reason for ensuring that you have sufficient power set to allow the aircraft to be turned in the desired direction. Incidentally, in this case, you may need to turn a little before the aircraft stops so that as the nose goes through the vertical the aircraft has indeed stopped rising.

I have never seen a proper stall turn performed with the engine at idle. The aircraft will always flop onto it’s belly or back depending on which way it was leaning at the top of the turn. If you have always succeeded in stall turning with the engine at idle, either it’s a high idle or else you turned earlier than you should. If you have minimal airflow over the rudder and elevator don’t expect to get much, if any, control out of them.

Finally, the B is not flown as a schedule unless the pilot wishes to do so. If you do want to fly it as a schedule, then make sure that you are able to cope with a schedule since getting out of position on one manoeuvre puts you in a bad place for the next manoeuvre. With the B you generally fly one manoeuvre followed by a positioning circuit. However, for the stall turn, if you feel up to it, then there is no reason why you should not go from the second of the 2 rolls into the stall turn. If you prefer to fly round the circuit after the rolls then you are perfectly entitled to do so. If the examiner insists on you flying the stall turn after the 2 rolls ask them where this is set out in the guide. That should be the end of the matter! If it isn’t, refer the issue to the Area Achievement Scheme Coordinator as he has an examiner who’s implementing something other than what is laid down by the BMFA. It is not up to individual examiners to change the requirements of the B as set you by the Achievement Scheme Review Committee of the BMFA.

As regards calling “manoeuvre start” and “manoeuvre stop” it is a useful ploy to make sure that the examiner is aware that you have started and have finished. Again, not something that is mentioned in the guide. I would expect the examiner to tell the candidate what manoeuvre he wishes to see next performed either in the order in which they are listed or, if this has been agreed before-hand, in some other order, although I cannot, off hand, think of any reason why this should be required. If you forget what manoeuvre you are meant to be doing, there is no reason why you should not say to the examiner “I’m sorry, I’ve forgotten which manoeuvre you asked me to fly”. If there is insufficient time between him telling you what it is and beginning the manoeuvre then say “I’ll fly round again”. Better that than rushing into it and making a hash of things. There is no need for a caller as there is in a competition since the Examiner fulfils that purpose. The B is not a memory test!

[Ultymate]

"Never close the throttle before you apply rudder to start the turn".......is what you said in your last post Peter, perhaps the word completely is missing ??

[Peter Jenkins]

You are absolutely right Ultymate - I plead guilty to being careless with my language. I know what I meant to say but I wrote something else! Am I forgiven?

[Willyuk]

Thanks Peter that helps a lot as I have had trouble with the flopping scenario.

[Ultymate]

I grant you absolution

[Peter Jenkins]

[Gordon Brown]

Hi Peter, glad to see you are keeping up the good work, the posts about the B test have led to one of the BTRMAC members suggesting we set up a B test class in the spring when more of us are able to get together and the weather is a touch kinder. So far about half a dozen of us will be practicing for the test and using your notes here to help us along. Perhaps it will help me get to grips with the Monolog! It might also stop Nat from nagging at me about my standard of flying...

Gordon

[Terence Moore]

As a casual observer of this forum, a BMFA instructor and examiner, I have no problems reminding the candidate of his/hers next manoeuvre in the flight test. I also do not expect it to be flown as a "schedule".

With the stall turn, at the top of the climb, it is important to maintain airflow over the tail surfaces, sometimes a burst of throttle can help at the right time.

I also point out the geometry of the vertical climb i.e. due to the angle between "line of sight" and apparent vertical, it should appear not quite vertical. Easier to explain with a sketch, than in text.

[John C]

Posted by Terence Moore on 13/11/2014 18:20:51:

I also point out the geometry of the vertical climb i.e. due to the angle between "line of sight" and apparent vertical, it should appear not quite vertical. Easier to explain with a sketch, than in text.

Surely a vertical looks vertical whatever direction you look at it? For example, a lamp-post appears vertical whether looking along a street or from the opposite side of the street.

["L"Plate]

I am interested in this. I have seen in full size an effect in long verticals that make it look as if the aircraft is curving away from the viewers point but not been told or noticed this at model scale.

Please explain further Terence.