For Starters – Part Three

For Starters – Part Three

This time we’ll move on to more ‘hands on’ R/C aeromodelling, exploring what the controls of your transmitter do and how they affect your model aircraft in flight. We’ll also begin to examine things from the instructor’s viewpoint with some words of guidance to help you get the most from each day at the patch. Let’s kick off by looking at an R/C transmitter (commonly abbreviated to Tx) and how its operation affects a model’s controls. There are two arrangements concerning the positioning of controls on a Tx, known as ‘Mode One’ or ‘Mode Two’. The arguments over which is best has rumbled on since R/C went proportional, but in practice it makes little difference. What is important to a novice, though, is to try and mimic the control configurations used by his instructor.

On a Mode One Tx the left stick controls the elevator and rudder inputs, the right stick controls the throttle and ailerons. This splits the primary flight controls (aileron and elevator) across the two sticks. For Mode Two, the left stick controls throttle and rudder whilst the primary flight controls of aileron and elevator are combined onto the right stick.

Moving the elevator stick back towards you (commonly called ‘pulling back on the stick’) will raise the nose of the model in level flight. Moving it away (or ‘pushing down’) from you will lower the nose. Moving the aileron stick to the left or right will cause the model to roll in the corresponding direction. This movement is how turns are initiated, followed by an input from the elevator stick. Note that one of the Tx sticks will have no sprung action to return it to the centre when it’s moved. This is the throttle control. The position of this stick is often determined by a ratchet, although a smoother non-ratchet action is also quite common nowadays, the advantage being that it permits finer throttle control. Full throttle is achieved with this control pushed fully away from you, and engine idle is achieved with the stick all the way back towards you. The throttle can be quite difficult to set up, so don’t be surprised if one of the first jobs your instructor has to do with your model is re-set the throttle linkages to improve control of the carburettor.

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The remaining function, the rudder, affects the yaw axis of the model, and until your training is progressed sufficiently you might only use this function with the model on the ground. That’s not to say it’s unimportant, though. The rudder is a necessary flight control. More so in aerobatics, or on certain types of model that require it to be used during turns. You may see some more advanced models at the patch that have no rudder fitted at all, which is quite common.

TRIMS
Alongside each of these four controls on the Tx youll find sliding levers or, more commonly these days, digital switches. These are the trim functions for each control. What they effectively do is alter the neutral position of the related control. Thus, by using them when the model is in the air you can cancel any out-of- balance forces that make the aircraft tend to climb, dive, roll or turn. Rest assured, you will learn how to use these soon enough.

Get very familiar with your Tx. Hold it as if you were flying whilst sitting watching television in the evenings and try to get to know where all the controls, switches and trims are, simply by touch. When you actually have your model in the air there won’t be time to look at the Tx to find out where a particular control is located, and if you do so you’ll probably be unable to find your model when you look back again! This is especially so in a crowded sky full of identical ARTF trainers!

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Ok, having told you all about the controls on your radio, let’s see how these directly relate to the controls on your model.

FUNCTIONS DESCRIBED
Elevator. This is used to control the ‘pitching’ axis of the model, and is generally the function used to hold the model level. As we’ve established, backward movement of the stick will cause the nose to rise and the aircraft to climb, although not for long unless power is increased. Similarly, forward movement of the stick will cause the nose to go down and the model will dive, building up a lot of speed unless power is reduced. So, you can see to some extent that the throttle and elevator controls do affect one another. An increase in power in level flight will cause a typical trainer to climb unless the elevator stick is moved forward to hold the model level, or a modification to the trim is made to compensate. In either case the model will fly faster if kept flying level.

Similarly, if power is reduced the model will begin to slowly descend unless the elevator stick is held back (‘up’ elevator), in which case it will fly more slowly. If the aeroplane slows down too much it reaches a point where it won’t fly anymore and will then stall. If you find that you need a constant pull or push on the stick to hold the model level, then you need to use the trim facility mentioned earlier. Just move the trim lever in the same direction as the pressure you’re using to hold the model level, until it flies level with the stick at neutral.

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Your instructor will be capable of trimming your model for straight and level flight very quickly after take-off, and the crescendo of digital beeps emanating from your Tx may surprise you at first. With time and practice, you’ll be able to do the same.

Aileron
This is used to control the model through the ‘roll’ axis. Youll use aileron to keep the wings level when you want to fly in a straight line, and to bank the model as you start or finish a turning manoeuvre. With the wings held level the model will fly in a straight line; of course you can’t do this forever and so must make turns to keep the aeroplane within sight. Moving the aileron control to the left or to the right will cause the model to bank in that direction; when it’s banked about 20° or so, neutralise the aileron stick to stop the model banking further. Your aircraft will now slowly turn, but it will also tend to drop its nose as you’ve effectively reduced the horizontal lift component provided by the wings. Be ready to apply a little ‘up’ elevator to keep the nose level through the turn.

Incidentally, this elevator input will not only adjust the pitch of the aircraft it will also help the model in the turn, as rolling into a banked position causes the elevator (which is no longer horizontal at this point) to provide some additional turning force. To straighten out from the manoeuvre, simply bank the model back until the wings are level and relax the back pressure on the elevator until the model is once again in straight and level flight.

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Aileron control is one of the trickiest to master for new pilots, especially as it often seems that the model is doing the opposite of what you’re asking it to do. With the model flying towards you, a simple method of remembering which way to move the stick to regain level flight is to ‘prop up’ the lower wing with the stick, i.e. move it in the direction of the lower wing.

Rudder
During the preliminary stages of your training you’ll find that you don’t need to use the rudder very often. It’s still a useful function though, controlling the ‘yaw’ axis, and it comes into its own during taxiing and take-off (the rudder may also be linked to the nose or tail wheel to give more accurate ground control). Your instructor will show you how the ailerons can be substituted by the rudder to steer your model in the sky, and how the rudder is introduced into aerobatics. Anyone using a four-channel trainer will soon discover that you generally don’t need to use the rudder at all during initial flights, as turning is accomplished entirely by the use of the ailerons and elevator. Aileron and rudder controls have a similar effect on your trainer due to the high wing configuration and its associated dihedral.

Throttle
This control determines the amount of power the engine provides. Full throttle is used for take-off, overshooting and many aerobatic manoeuvres. Low throttle settings give glide, taxiing power and, with the trim fully back, ‘engine stop’ facility. Intermediate throttle positions are used for different conditions of flight. The power setting that gives a pleasant, relaxed flying speed (neither too fast nor too slow), is known as ‘cruising speed’; the setting for this varies between models but is normally slightly less than half throttle, and will be indicated to you by your instructor. As we established in the ‘elevator’ notes above, the throttle function can also control the climb and descent of the model.

LISTEN UP
So with a knowledge of what the controls actually do, we’re almost ready for our first flight. However, there’s one key point to understand before getting airborne. This whole training scheme is underpinned by the very person in whom you put your trust each and every time you fly your trainer. Your instructor. It’s with his help that you’ll succeed in becoming a qualified R/C pilot. You must learn to respect the fact that your instructor is your key to success. His role cannot be underestimated.

Everybody wants to be free of an instructor as soon as they can, but the time its takes for you to become a ‘qualified’ pilot will depend largely on you. No two people progress at the same rate; some are ready within in a few months whilst others may take a full season or more. However, there are a couple of factors that will help you speed up the process:

  • Liaise closely with your instructor and mutually arrange to fly as often as you can. Were you provided with a contact list of instructors when you joined the club?
  • Ensure that your model and equipment are in proper working order when you come to the flying field (i.e. batteries charged, pushrods and connectors checked and secure, etc.)
    Also, if an instructor has spent time setting up your model, don’t go away and tinker with it for the sake of having something to do. He’ll soon get fed up with you if you repeatedly remove the radio gear, strip the engine or play with the linkages.

    Your chosen club will probably have several members who are both willing and perhaps specially appointed by the committee to teach newcomers how to fly. Each instructor has his own personal traits and consequently you may find that different instructors will teach the same task in a different way. Accept this with the knowledge that no matter how you are taught, the end goal will hopefully be the same. Good instructors recognise that their ways are not necessarily the only ways of achieving the same result, and if needed they’ll adjust their methods to suit you.

    There are a number of other points that need to be emphasised to enable you to aid the various instructors in getting you that coveted BMFA ‘A’ certificate:

  • Your instructor’s word is law when your model is in the air. If he tells you to do something, do it immediately without question. The reason may not be apparent at first, and you may by all means discuss it on the ground after the flight if necessary. But obey implicitly whilst your model is flying. Remember that training is a privilege.
  • Wait your turn. The system by which you’re allocated an instructor can vary from club to club and is often tailored to suit the number of instructors on the field at any one time, depending on how they wish to teach. Follow the example of others to ensure you get your fair share of flights.
  • Be ready. An instructor’s time is precious and may have to be shared between numerous individuals at any one time. Don’t waste it by not being prepared for your flight.
  • You should not hold your instructor responsible if your model crashes during a test flight or at any other time. No responsible instructor will allow your model to crash if he can possibly avoid it, and he will do all he can to prevent it from getting into a situation that could result in an accident. But he’s only human, and during your training there’ll be many occasions when you’re required to fly near the ground where safety margins are very small (take-off and landing, for example), so hard landings (and worse) are an unavoidable hazard of the sport. Accept these hazards and trust your instructor.
    COMMUNICATION
    In describing what he wants you to do, if the instructor says (for example) turn left, he will expect you to move the Tx control to the left, and consequently the model will turn to its left. ‘Up’ and ‘down’ commands should require no explanation by now.

    This section can be reinforced by reading through the relevant parts of the BMFA’s own training manual ‘Up and Away’. When you join the BMFA you’re given the option of redeeming a voucher for a copy of this manual, which is a very useful reference tool covering many aspects of R/C model flight. My advice is to endeavour to get your hands on a copy if you don’t already have one. Speak to your instructor or club secretary and they should be able to help. Additional copies are always available from the BMFA’s headquarters for a small fee.

    Next time I’ll be offering some guidance for instructors on how to begin teaching this scheme. Until then, here’s a useful pre-flight check list for you to copy and keep in your flight-box or Tx case:

    Pre-flight checklist

    PC users: Right-click the links and select ‘Save target as’
    Mac users: Hold down the ‘control’ button and click the links, selecting ‘Save linked file to…’

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