How do you achieve tight turns ?

[Geoff Bradley]

Well - all is going well towards my A Cert but I'm having problems achieving tight turns without the nose dipping and losing height.
This is even more problematic in windy conditions!
I've discussed it with my instructor but can't seem to crack the problem so I'm hoping that someone may be able to get the solution into my thick old skull.
Any advice whatsoever will be gratefully received.

[Greybeard]

Two questions: What sort of model are you flying and has it got ailerons?

and why do you need to do tight turns for the "A" certificate?

OK. I can't count, that's three.

[Geoff Bradley]

I'm flying an Arising Star which has ailerons.
Perhaps my perception of 'tight' is not correct !
My trainer wants me to turn and level off when doing the figure of eight and that's when i'm having the problem.

[ken anderson.]

hello geoff...make sure the model is trimmed for hands off straight and level......if you are talking about the test ....... try and do everything at a constant throttle setting(not too fast) and be gentle on the sticks........ constant practice is the thing......do the largest figure of 8 you can-as as small one's tends to end up in tight turns and the model losing height etc.....imagine that you are sitting in the aircraft.....

ken anderson ne..1 ...... imagine dept.

[Devon Flyer]

Posted by Geoff Bradley on 09/06/2013 15:19:35:

My trainer wants me to turn and level off when doing the figure of eight and that's when i'm having the problem.

According to the current BMFA handbook, the figure of eight should be done as two circles - there is no option to level out during either side of the figure. ie. it should be a constant turn.

Maybe he is still teaching to the 'old' 'A' test schedule? This allowed the candidate to do a 'lazy' eight if they so wished. This option was scrapped a couple of years ago.

[Geoff Bradley]

Thanks chaps - he is probably just tring to improve my flying skills by making it more difficult,if so, that can't be a bad thing .

That being the case - how do I manage tighter turns ?

[Olly P]

Geoff - that depends how tight!

OK, when we enter the turn using aileron, we bank the aircraft. This means the wings are no longer producing lift which is directly in opposition to gravity, but rather at an angle to it. Some will be produced vertically up (against gravity) and some will be sideways (causing the turn).

If (as I read it) the problem is the nose dipping then there are a few possible issues, firstly insufficient speed entering the turn therefore the amount of lift fighting gravity is not enough, second the model is almost in a 'knife edge position' and no rudder has been fed in to maintain the nose attitude.

There are other posibilities but Iactually think if you are trying to tighten the turn and have gone 'too far' onto our side for the manner you are flying then the problem is actually a lack of co-ordinated rudder - if you bank a little rudder will help hold the nose up.

Prof Dave (Aka BEB) has been doing some mag pieces on control harmonisation recently, I'm sure he has mentioned the rudder the articles are well worth a read.

[Geoff Bradley]

Thanks Olly - that seems to make a lot of sense so I'll give it a try and dig out the mags to have a nosey.

[Olly P]

Just remember to practice 3 mistakes up....

[Geoff Bradley]

Will do

[Bearair]

Posted by Geoff Bradley on 09/06/2013 18:47:08:

Thanks Olly - that seems to make a lot of sense so I'll give it a try and dig out the mags to have a nosey.

It might seem to make sense but its also completely wrong! IMHO

"you don't use the rudder to control the nose up or down in a coordinated turn, you use the elevator. The rudder is used to keep the turn coordinated.(Overcome the yaw created by difference in lift between left and right wing.)

As you enter the turn (starts to bank) the correct deflections are:
1. Apply aileron in the direction of the turn.
2. Almost at the same time as you apply the aileron you start to give some rudder in the same direction.
3. As the aircraft starts to bank smoothly increase elevator to keep the nose at the same attitude. (Or slightly higher.)
4. When you have the desired bank angle, ease off on the aileron deflection, at the same time as you decrease rudder deflection. In order to maintain the same bankangle you gonna end up with having to actually put in some aileron in the OPPOSITE direction as you are turning in.

This mean that established in a turn the controls should be: Back pressure on the elevator, rudder in the direction of the turn and aileron in opposite direction of the turn"

This was the best explanation I could find.

For the A test and indeed the B the use of a co-ordinated turn using rudder just is not required. Concentrate on getting a resonably tight turn without using rudder. You may find you have to increase the amount of elevator through the turn (ie increase AOA)

[Biggles' Elder Brother - Moderator]

You are quite correct Bearair - to be fair to Olly I do think he was refering to the rudder in the context of being nearly knife edged.

So, Geoff picking up on what Bearair says the secret of a tight turn is elevator. But,...there is a note of caution needed here.

Olly is quite right when he says that in a turn some of your lift is directed to making the turn - you can put more overall lift in via the elevator as Bearair says - so that's more upward lift and more trurning effort - so you will hold hieght and turn tighter. But this extra lift is being generated by increasing the angle of attack. Now, contary to what many people seem to think aeroplanes don't stall because they are going too slowly - they stall because the critical angle of attack is exceeded. So you have to have some respect for this - pull on that elevator too hard - ie try to make the turn too tight - and you will stall - no matter how fast you are going!

For more detail on this read my article in the March 2013 edition of the mag.

BEB

[Olly P]

Indeed - I was referring to the 'near knife edge' condition as I am assuming that more aileron has been put in as an attempt to make the turn tighter (an instinctive thing I have seen many new pilots do - and I have done including FS)

Indeed if you are not in a knife edge or near knife edge condition, then elevator is the way to keep the nose up and tighten the turn.

While coordinated rudder is not a requirement of the A-test I would suggest it is a good habit to get into early, certainly when flying full size you wouldn't be sent out solo unless you used it!

As with everything the key is practice!

[Frank Skilbeck]

Geoff, you just need to get used to maintaining height with a little elevator in the turn. As Olly states practise is the answer, keep doing it until you can fly a controlled turn without losing or gaining height.

[Bearair]

Posted by Olly P on 10/06/2013 09:31:34:

Indeed - I was referring to the 'near knife edge' condition as I am assuming that more aileron has been put in as an attempt to make the turn tighter (an instinctive thing I have seen many new pilots do - and I have done including FS)

Indeed if you are not in a knife edge or near knife edge condition, then elevator is the way to keep the nose up and tighten the turn.

While coordinated rudder is not a requirement of the A-test I would suggest it is a good habit to get into early, certainly when flying full size you wouldn't be sent out solo unless you used it!

As with everything the key is practice!

If the model is in a near knife edge condition because you have rolled to much you straighten it out by using opposite aileron, I would of thought. You NEVER EVER use opposite rudder in a turn full stop whether your in full size or not. And I havn't seen that many full size aircraft without a rudder and yet there are thousands of model aircraft that do perfectly good turns every weekend without the aid of rudder.

Keep it simple stupid! is the code I try to follow when training people for the achievement scheme in fact KISS is a very good rule to remember when learning to fly model aeroplanes. Most modellers in my experience never have a need for rudder in the turn, it is only certain types of model that require it.

"Indeed if you are not knife edge or near knife edge condition, then elevator is the way to keep the nose up and tighten the turn." Even if you are in knife edge elevator is still the way to tighten a turn, opposite rudder will straighten the turn up if anything!

Practice is indeed the key to everything I agree, but not if the advice given is wrong! You will be practicing the wrong thing! Co ordinated rudder (in a turn, not a roll) is not opposite to the direction of the models turn!

I hope I havn't offended anyone in my replies, but I do think it highlights a problem that many beginners face, not sticking to the basics and unfortunately well intentioned but incorrect advice!.

When you have passed your A test is, in my opinion the time to practice the subtle arts of flying model aeroplanes, indeed it is those subtle arts that keeps the hobby fresh for me after many years.

Roger

[Geoff Bradley]

Once again thanks gents for such detailed info. It all seems common sense when explained well - all I have to do now is practise, practise and more practise !!!!!

Onwards and upwards - perhaps not - that would be too much elevator !!!!

[Olly P]

Roger - none taken!

I perhaps focussed too much on one element of the opening post "nose dropping and losing height" and then made the assumption that Geoff was rolling further to get a tighter turn (a common thing) at a near knife edge condition, rudder holds the nose up.

I agree that in any other condition the elevator is the control to use to maintain the attitude of the nose.

The elevator is used in any condition to tighten the turn at a given angle of bank.

I will have to mention to my former instructor (a full size commercial pilot and former champion Cross-country Glider pilot) that he taught me incorrectly in using opposite rudder in some turn conditions....

I am now going to withdraw from this discussion, as it appears my advice is not wanted/needed by anyone other than the OP.

Olly

[Bearair]

Sorry Ollly, but despite you saying you have not taken offence, I would conclude by what appears to be your rather petulant following remarks you have!

I really do not no how to put it any more nicely than I have, I think you simply gave the wrong advice to a beginner. You do not put opposite rudder in a turn with an Arising Star to tighten the turn up or raise the nose. Maybe in a sideslip? I dont know.

It is a pity you have withdrawn from the discussion, because I would really like to know when you apply opposite rudder in a turn as your glider champion, commercial pilot instructor has taught you. I genuinely would like to know because i cannot envisage such a situation. And I am always eager to learn and except the fact I am wrong if it proves to be so. I am too long in the tooth to have an ego to bruise, even on a public forum. As I said, learning the subtle arts is my great joy in flying toy aeroplanes and what keeps me going.

Roger

[Olly P]

Sorry if they came accross as petulant, I am a little busy at work so snatching time to put stuff onto here.

I will comment only on the when I have been taught bit, as I think I have covered your other, bold, comment in my post above.

When pulling a very steeply banked turn (upto 90 Degrees banked), in a glider or stunt aircraft with a very small C/S on the fuselage the nose will tend to fall away. if the turn is maintained at a steep angle of bank then opposite rudder can be used to keep the nose up.

Rudder should be used throughout a turn to prevent either side slip or skid of the aircraft and is judged in full sized craft either by the 'ball' or string method normally.

Turns in which you bank to such a steep angle are made generally during racing events, if you watch the Red Bull air races or full size pylon racing you will sometimes see it, but generally it happens when there is a requirement to circle something in a race (i.e. the turn is prolonged), in a short duration turn it is actually faster to kick the nose up slightly as you bank over so that the fall off leaves you exiting the turn with a flat attitude.

Hope that explains!

[Bearair]

Well I have only flown Sport 40 and Club Twenty in pylon racing and I am learning the art of F3F and I believe that I have never used opposite rudder in a turn, the way you adjust your nose attitude in the turn is by getting the differential right on the set up of the model. So for instance with a F3F glider I have different settings for aerobatics or for tight turns. With F3F I am looking for a slightly nose down attitude as the model goes through the turn, and this means I am using diferential differntly than would normally be the case.

Of course a full size aircraft cannot possibly turn faster than a model because the pilot would pass out. But it would indicate to me that there are times when because we are not flying fullsize aircraft we can push the boundries beyond full size capabilities, to a point when fullsize experience becomes irrelavant. Some of the 3d stuff does this aswell.

Take Dynamic Soaring as an example where models are turning at 400 hundred miles an hour without rudder!.

So in conclusion your instrutor may well be right, but we are flying models so we can set the model up for really tight turns (ie pylon racing) with a combination of differential, snapflap and elevator.

Roger

Edited By Bearair on 10/06/2013 12:41:49

[Mark Stringer]

Just to add my two penneth worth here .. i am with the elevator clan.

You start and end a turn with ailerons (and control it if needs be - plus a little rudder doesn't do any harm depending on the model) but actually perform it with the elevator.

So you feed in a little aileron to start the turn and as you do you add just enough elevator to take over - you should be able to centralise the aileron now and control the amount of turn, whilst maintaining height, using the elevator. (If you keep the elevator on you will be able to circle you model at a constant height forever (or until the fuel / battery runs out - LOL!) - so that may be a nice way of just practicing the turns first to get you used to holding it in circles before worrying about going the other way.

To straighthen back up use the ailieron and as you do so reduce the elevator back to neutral.

So a nice figure of 8 will be ... aileron into elevator into aileron into elevator etc.

If you practice that until you get used to it based on maintaining height it should make it pretty easy as the first circle will lead nicely into the second and all with smooth small commands on the sticks.

The other thing to bear in mind is wind speed and direction as you may want to throttle back a little on the downwind leg to prevent the model zooming (gaining height through lift due to speed) and with this in mind practice will let you decide which way you like doing your figure of 8 (cross wind or with the wind)

Hope this helps a bit and good luck

All just my opinions of course and everyone has their won way of doing things.

[will -0]

Hello, not sure if it's already mentioned or not (tl:dr) but it's worth pointing out that:

1)the tighter the turn, the more elevevator you'll need to keep the nose up

2)if it's quite tight that will also increase drag, so you may need to lean on the loud stick a bit

3)your stall speed goes up (with all that pulling elevator) so in extremis you may flick out of the turn (which in the case of a trainer should be recovered by imediately relaxing the back pressure to prevent a spin and then recovering in the normal way).

If that's all you want to do stop reading here.......

[not relevant to an arising star]

as has been pointed out, the amount of rudder needed to fly well varies from aircraft to aircraft, and for that matter depends on how fast you're going. Most trainers are not too demanding in this respect and will fly quite adequately without use of rudder in the air. That said it doesn't harm to learn to use it and it will certainly fly better and increase your skills if you do!

There are special reasons for using a tiny bit of out of turn rudder whilst circling a (FS) glider. Basically it goes like this:

In a continous slow relatively steep banked turn to keep a glider balanced (ie not yawed) you generally require a small amount of into turn rudder and a small to large amount of out of turn aileron*. An easy way to think of the reason for this is that the outside wing is going much faster than the inside wing because it has a larger circle to go round and so generates more lift tending to roll the glider into the turn.

This means that if you're balanced you have constant aileron deflection which means that the portion of the wing fitted with ailerons is no longer in the shape of aerofoil as per designed and can be more draggy.

Instead of flying balanced like this it is also possible to fly with the ailerons not deflected, but a bit of out of turn rudder on instead (using the secondary effect of yaw ie roll to counteract the into turn roll tendency) Practically this appears to help (glider climbs better), but sometimes these things are all in the mind.

[/not relevant to an arising star]

*for example in a Slingsby T21 it is possible to be continuously turning left with full right aileron (and the string in the middel ie not yawed)

[Olly P]

Roger - indeed, models and full size are different, and this is why I do agree that elevator is the key control at the majority of bank angles.

When at knife edge however the elevator is pointing the 'wrong way' to assist with nose angle, hence why the rudder comes into play....

Mark - I think that we said that earlier, Elevator is the key to adjusting the radius of the turn once entered, and unless close to a knife edge position also controls the nose.

I think all we have done is in a round about way come back to the same combination as mine, Rogers, and BEBs first posts - at 'normal' bank angles for a turn the elevator is the key control surface for controlling both radius of the turn and attitude of the aircraft, at knife edge or very steep bank angles the elevator still controls the radius of the turn, but the rudder takes on greater importance on the attitude of the aircraft.

Olly

will - we cross posted - and I have done that in a T21, very strange feeling.....

Edited By Olly P on 10/06/2013 13:59:20