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Getting Started on RC Helicopters – Part 6 (Learning to fly)

May 10, 2010 Leave a comment

In this (very long) post, i will go through the several stages of learning to pilot a RC helicopter. I can tell you it will not happen without practice and time, so keep your anxiety controlled. But, if you follow these guidelines, you should be able to progress in your skills and soon will be flying like Tareq Al Saadi!

Level 1 – The hover

This first step into flying model helis is probably the hardest part to learn, mainly because you have to do it yourself. Of course an instructor can hover your model and show you the basic controls, he will make it look very easy but at least you know that if he can do it, the model must be okay. On your first attempt at hovering you might wonder what you have got yourself into as it seems almost impossible, don’t worry, its like riding a bike and once you can hover there is no going back.

You will need to fit a training under carriage, there are two types, crossed sticks with balls on the end or crossed sticks with a standard hula-hoop attached, either type is okay and they are usually fitted using cable ties.

Whatever radio you use make sure you have the best gyro you can afford as this will make control of the tail a lot easier. If you can get your hands on a good simulator it will help considerably, and at around £100 if you have a PC, it will be money well spent.

Try to choose a day with little or no wind and make sure you keep the model pointing into wind as this will help to keep the tail straight, all you are trying to do at this stage is to keep the model hovering on the spot at about 1 to 6 inches (25mm to 150mm) high, if it gets any higher, lower the throttle, land and try again. Just keep practising for as long as it takes, it will probably take several visits to the flying field to perfect the tail in hover.

So you can hover tail in and land fairly smoothly. Do not remove your training under carriage; it will still be useful for the next step, which is hovering side on. You can do this by hovering diagonally and gradually turning the model side on as you progress, make sure you practise on both sides of the model, it is very easy to get handed and once you have got the habit of hovering only your favoured side it is hard to get out of.

All the above will take many hours of practise to perfect so take your time and don’t remove your training under carriage until you feel you are ready to do so, you may want to move directly on to learning the nose in hover while you have it on, or you can leave nose in hovering until you can fly circuits when you can gradually fly the model towards yourself until you can stop and hover, which way you do this is up to you as I have seen it done both ways.

Remember, the most important things you will need to become an RC Heli pilot are patience and determination.

Level 2 – First Circuits

Before we get into the flying, set your lower pitch to about minus 2 degrees with 5 to 6 degrees in the hover position and 8 to 9 degrees at the top. It is also useful to set up the radio so that the throttle trim gives you tick over in the middle, idle up at the top and engine cut at the bottom. You should be able to achieve this using the travel adjustment (not the throttle curve) on the transmitter, if not you will have to adjust the throttle servo arm as required. You should now fly the model with the throttle trim at the high position; this will keep the engine revs up when in negative pitch there-by giving more control. As with learning the hover it is a good idea at this stage to get an experienced pilot to fly the model and adjust the trims as required, this will make it much easier for you.

Start with the model tail in, facing into wind, at a height that you are happy with, then hover over to your left side, back to the middle and then to the right side, keep practising this with the tail in then gradually turn the tail to follow the direction of the model and without stopping in the middle. The turns are initiated by applying lateral cyclic (aileron) to produce a bank, together with tail rotor (rudder) to make the tail follow the turn. The amount of aileron and rudder applied will vary according to the forward speed of the model and whether you are turning upwind or downwind. With practise this will eventually become a figure eight with the turns at both ends away from you and at the same height all the way round.

Do not be tempted to fly the model in a circuit around yourself; this is bad practise as most flying sites will not permit you to do this, so all flying should be in front of the pilot and anyway, you will not learn much from this as the model is in the same situation relative to you, all the way around.

Some pilots find the transition from forward flight to the hover quite difficult and avoid this manoeuvre by stopping the model at height and lowering the model vertically to land. This looks very untidy and if you are ever going to fly in a scale like manor you will have to approach at 45 degrees, you will also need to be able to do this to learn autorotations.

To return the model to hover from forward flight reduce power and apply back cyclic, adjust the amount of each control to achieve a 45 degree approach. Ideally the approach should be into wind but make sure you practise from the left and right to avoid getting handed.

As you gain confidence with flying circuits try to gradually make them higher and faster. The height will be useful later when you attempt new manoeuvres, giving you more time to correct a mistake before the ground comes up! Also don’t be afraid to fly on a windy day, I have seen many pilots build up a fear of the wind and you can’t let the weather stop you flying, particularly if you live in the UK.

Remember, the only way to learn is stick time and lots of it.

Level 3 – Autorotation

There are many pilots who advance to quite a high level of flying yet never bother to learn autorotations (autos), a comment often heard is “why stop an engine that is going perfectly well”, fair comment I suppose but what if your engine cuts, chances are you will panic and crash the model. So there is one good reason to learn autos, the other reason being the shear satisfaction of landing your model time after time with no engine power. I having gone through many stages of learning to fly but I found the autorotation the most rewarding of all.

During autorotation the negative pitch will control the glide angle of decent, this will be about minus 3 degrees but will vary according to wind conditions, blades, and forward speed during the auto. I always set my negative pitch to about minus 5 degrees and then adjust the pitch with the stick to get the ideal decent angle.

Before you start, you will need to set your throttle hold switch so that it gives a reliable engine tick over when operated. If your tail is driven during autos you should set the tail blades with no pitch when the hold switch is operated, as there is no torque from the rotor head during autorotation the tail does not need any counter acting pitch. You must be able to perform a 45 degree approach and landing before any attempt at autos. Also make sure you are familiar with the throttle hold switch position on the transmitter, you will need to find it quickly while practising.

To give you an idea of how much power is in the rotor head with no engine power, from the ground, raise the throttle until the model is light on the skids, switch to throttle hold and gently add pitch, the model will hover for a short time.

Start by flying your normal circuits at a safe height, when flying into wind hit the hold switch and apply negative pitch, the forward motion of the model should keep the tail straight, if the tail kicks to the left or right return the hold switch to normal and land the model, adjust the tail trim and try again. Once you are happy with the tail trim keep practising autorotation descents but only down to a height that will give you time to abort (return the hold switch to normal). After hours of practise you will be able to descend at 45 degrees, apply back cyclic to flair (stop the forward speed) and add pitch to land. The difficult part is the timing of all this, if you add to much pitch to early (to high) you will use up the inertia in the rotor head and will not have enough to land. If you add pitch to late the result is obvious.

Autorotations are easier with a 60 size model due to the extra blade power but wither it’s a 60 or 30 size model, the type and weight of the blades will have a major effect on auto performance, use glass/carbon blades like SAB or TG for best performance.

Keep practicing, but remember – it is supposed to be fun!

Level 4 – Setup for Aerobatics

Most transmitters will have three flight modes available via the flight mode switch (sometimes called the idle up switch), this will give you three pitch and throttle curves, one for normal hovering, one for aerobatics like loops and rolls, and the third one can be set for more extreme 3D type flying.

Throttle Curve 1 - Normal

Throttle Curve 1 - Normal

Throrrle Curve 2 - Stunt 1

Throrrle Curve 2 - Stunt 1

Throrrle Curve 3 - Stunt 2

Throrrle Curve 3 - Stunt 2

During aerobatic manoeuvres negative pitch is used during the inverted sections so the throttle curve is set so that it will not drop below 50%, while you have full pitch control. These high throttle curves should only be switched in when flying and not before take off as the engine will over rev in this situation.

Pitch Curve 1 - Normal

Pitch Curve 1 - Normal

Pitch Curve 2 - Stunt 1

Pitch Curve 2 - Stunt 1

Pitch Curve 3 - Stunt 2

Pitch Curve 3 - Stunt 2

The main difference in pitch curves will be in the negative section where up to minus 8% may be used for inverted flight, where as for the hovering mode minus 1 or 2% will be ideal. It is also useful, in the hovering mode, to flatten out the curve at the centre point to make the model less sensitive.

Revolution Mixing

This is available on most transmitters and is quite simply a mixer, which adds pitch to rudder to correct tail swing on adding power. However it is not always easy to set up and if you have one of the latest piezo gyros with heading hold, you probably wont need it.

Cyclic to Throttle Mixing

Some transmitters have dedicated mixers for aileron to throttle and elevator to throttle but you can use any free mixers, try about 20% throttle to start with and if possible only on flight mode 3 for more extreme manoeuvres. Be aware that if your throttle is already flat out, the mix will try to add more throttle and could overdrive the servo, some transmitters (like the JR PCM10) take account of this and therefore will not overdrive the servo.

So your model is now set up for aerobatics!

Rotor Head & Vibration

The main enemy in any model heli is vibration; this can be split into two types; high frequency and low frequency.

High frequency vibration usually stems from the engine, fan or clutch area and cannot easily be seen until cracks appear in the side frames or servos and other radio parts start to fail. All you can do is balance fan and clutch and all should be okay.

Low frequency vibration stems from the rotor head and normally shows as vibration of the tail boom and sometimes on the landing gear. Blade tracking is the first thing to check. Stick a strip of tape to the end of each blade, a different colour each end is required, as you bring the head speed up and looking at one side of the rotor disc you will be able to see if one of the blades is higher than the other (out of track) the different colour tape will tell you which one is high or low so it can be raised or lowered by adjusting the pitch control link.

The blades that came with your heli are probably wooden and will need balancing, how to do this is normally explained in the manual, however, I would try to use quality carbon/glass blades, I know they are more expensive but they do come ready balanced and their performance is far beyond that of wooden blades. I have used SAB, TG and NHP blades and have never had a set out of balance. I have not used any other make so I can’t comment.

Other sources of vibration can be the flybar, paddles and feathering spindle. Damper rubbers should be lubricated with silicone grease when fitting and the flybar must be centered with paddles of equal weight.

If your model has been crashed then the main shaft, feathering spindle and sometimes the tail rotor shaft will probably be bent and must be replaced. The feathering spindle can sometimes be straightened but for how much it costs it’s just not worth it. The main shaft must always be replaced as it could be weakened if straightened.

The rotor head speed on a model heli can vary from 1100 rpm to 2000 rpm at the extremes. Generally speaking the higher head speeds help stability, but things will wear more quickly, on the other hand if your head speed is to low the model will be unstable and sometimes the nose will nod up and down. The manufacturer should be able to tell you the maximum head speed permitted but good quality blades are recommended at higher head speeds. In my experience head speeds tend to vary from club to club as everyone sets up their model to sound like other models in the club, resulting in every member having a similar head speed wither its high or low. I run my Raptor 30 at about 1450 rpm in the hover, 1650 rpm in flight mode one, and 1800 in 3D mode.

So run a head speed no higher than you need to and don’t fly with any vibration and your model should perform well for a many hours.

Scale Helicopters

After several years flying model helis I was getting a little bored with throwing it around the sky at great speed and wanted something different. So scale was the way to go with so many skills required it was bound to be interesting.

There are three main ways into scale helis :

1.Buy a complete kit, which includes all scale parts as well as the mechanics. (i.e.Hirobo Lama or JR Ergo Robinson R22).

2. Buy a pod and boom model, which is also designed for use in scale fuselages (i.e. Vario or Graupner/Heim).

3.Buy a fuselage and fit your chosen heli into it.

Option 1 is the simpler and cheaper one although there will be less choice of models. Option 3 will require a higher degree of design and skill to build. Option 2 is I think the best option as once you have the pod and boom model you can fly it for some time to test and get used to it before putting it into a fuselage also there are plenty of scale fuselages to choose from.

Your choice of subject for scale might be your local police helicopter or a military helicopter or maybe one that you have seen on film, like the Airwolf, or it could be one that you just like the shape of. Whatever you choose remember that a full fuselage will always restrict access to the mechanics where as models like the Robinson R22 or Hughes 300 will be more accessible. This may not be a problem to you, but worth bearing in mind.

Three, four and five blade rotor heads can be fitted for more realism though they are expensive and have different flying characteristics to the standard two blade and flybar.

Also available from Vario are models like the EC 135, which has an enclosed (Fenestron) type tail rotor and the Notar which has no tail rotor but uses vectored air instead.

Flying a scale model is quite challenging and requires a great deal of accuracy to make it look realistic. Smooth hovering, slow climb outs and circuits, and nice 45 degree approaches are all part of scale flying. I prefer a model which flies well and looks realistic in the air rather than one which is accurate in every detail but is not flown due to the pilot being afraid of a possible crash, maybe the pilot lacks the confidence or has spent to long on all that detail!

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The Case for Mode 4 Transmitters…

This will be an interesting post. It could also be called “”How Most of the Planet Got It Wrong”!

Ok, let’s cut to the chase and soon you will understand what this means… 🙂

The great majority of RC pilots use transmitters set up in Mode 2. This post will set out reasons why that is a bad idea, and makes the case for using Mode 4. Most of the rest of the world uses Mode 1, which, while better than Mode 2, is still inferior to Mode 4 for most people.
So, what are these “Modes”? Transmitter Modes define what movements of the two control sticks control which of the main four control channels. The usual response I get when this subject comes up is “What on earth is Mode 4?”. I point out that almost everyone who has flown a three channel plane has flown Mode 4 – rudder and elevator on the right stick and throttle on the left. Yet when they get a four channel plane they do a very curious thing – they move the rudder to the left stick and put ailerons on the right stick, which is Mode 2. Why not just add ailerons to the left stick? If this was the only consideration the subject would be simply a matter of preference, with the choice of where to put rudder and ailerons being somewhat arbitrary. However, it goes much deeper than that. Let’s move on…

First, to be really clear, let’s define the four modes. In all cases left-right motion of the sticks controls aileron and rudder, and forward-backward motion of the sticks controls elevator and throttle. That leaves four possibilities, for the four Modes.

Mode 1

RC Transmitter Mode 1
RC Transmitter Mode 1

Mode 2

RC Transmitter Mode 2
RC Transmitter Mode 2

Mode 3

RC Transmitter Mode 3
RC Transmitter Mode 3

Mode 4

RC Transmitter Mode 4
RC Transmitter Mode 4

The difference between Mode 2 and Mode 4 is that the horizontal controls, aileron and rudder, are swapped.
The difference between Mode 2 and Mode 1 is that the vertical controls, elevator and throttle, are swapped.
The difference between Mode 1 and Mode 4 is that the entire sticks are swapped.
To understand why the choice of Mode is important, we have to look at what combinations of controls are used in flying RC. I believe the most demanding form of RC piloting is aerobatics, as practiced in pattern flying (like F3A) and in 3D. These tasks require coordinated, simultaneous use of all four controls. Certain combinations of controls are much more common than others, and it is the ease with which these combinations can be learned and executed that form the main argument in favor of Mode 4.
The fact that there are so many highly proficient 3D fliers using Mode 2 is a testament to the human brain’s ability to learn complex actions and to the perseverance of those individuals. The reason they use Mode 2 is because that’s how they were taught. This post is really aimed at someone starting to learn to fly, or who is moving from three to four channels. For someone already proficient in flying Mode 2, changing to Mode 4 would be very difficult, as would be any change of Modes. I started learning 3D flying to see if i could learn new tricks. The answer is “yes”, but it takes longer, and anything that could help the process was highly welcomed. Mode 4 was one of those things. The post concentrates on fixed-wing aircraft. We’ll leave helicopters aside for now, but i will come back to them later.

Continuous Rolls
The first maneuvers I attempted that got me thinking about this topic were the coordinated continuous roll, the rolling circle, and the rolling loop. For these the plane should fly horizontally, in a level circle, or in a loop, while continuously rolling about its longitudinal axis. All attempts I made to do these maneuvers in Mode 2 ended in disaster. Let’s look at why it is hard to learn. In Mode 2 a continuous roll, to the right for example, requires the following actions:
1. Move and hold the left thumb at the required throttle setting
2. Move and hold right thumb to the right (aileron – this sets the roll rate)
3. Move left thumb to the left (Left rudder)
4. Release left thumb and push right thumb
5. Release right thumb and move left thumb to the right
6. Release left thumb and pull right thumb
7. Release right thumb and move left thumb to the left
8. Repeat steps 4 through 7 to continue rolling.

The main thing that is difficult is the out-of-phase motions of the two sticks. There is a toy that has been available in the US for many years called EtchASketch. It draws lines controlled by two knobs, one of which moves the pen left-right, and the other moves it up-down. The motions of the elevator and rudder stick in a Mode 2 roll are exactly like the motions of the EtchASketch knobs for drawing a circle – something that can be done, but is widely acknowledged to be hard to learn. Another difficulty is keeping and controlling the aileron deflection to achieve a constant roll rate while working the elevator up and down, and maintaining the throttle while working the rudder back and forth. I found my plane would either stop rolling or that I had reduced the throttle, while concentrating on rubbing my tummy and patting my head, to which it has been compared.

Now let’s look at a Mode 4 continuous roll:
1. Move and hold the left thumb at the required throttle setting
2. Move and hold left thumb to the right (aileron – this sets the roll rate)
You can now forget about the left stick, except for minor adjustments to the roll rate if needed
3. Move right thumb to the left (left rudder)
4. Rotate the right thumb in a circle around the center – push, right, pull, left, … repeatedly.

To compare with EtchASketch again – this is like drawing a circle with a pencil – much, much easier. Moreover, since the left stick, throttle and aileron, hardly moves at all, it is much easier to maintain constant throttle and aileron, or to make minor adjustments to these controls if needed. Of course, in both Mode 2 and Mode 4 you have to coordinate the rate of movement of the sticks with the rotation of the plane. The difference between a straight roll, a rolling circle, and a rolling loop is largely in leading or lagging the plane’s roll with the stick motions. This is quite enough to think about without having to worry about getting the phase between rudder and elevator correct.
In Mode 4 that part is automatic.
For a right roll, the right thumb rotates to the right, or clockwise. For a left roll it rotates left, or counter-clockwise. Very natural.

Vertical Hover
This maneuver is controlled mainly by the rudder and elevator, to maintain the plane pointing vertically upwards. This tends to require small, rapid movements of the rudder and elevator, like balancing a stick on your finger. The throttle is adjusted to maintain altitude, and the ailerons are used to either counteract a torque roll, or to force a roll. These tend to be slow adjustments. As with the continuous roll, having a rapidly changing control on the same stick as a slowly changing control tends to make it difficult to maintain the slow control.
Again, hovering in Mode 2 can, obviously, be learned, but there is nothing very natural about it.
Consider what it takes in Mode 4. There are two main orientations – hovering “canopy-in”, where you are looking at the top of the plane, and hovering “wheels-in”, where you are looking at the underside of the plane.
Canopy-in: Consider the right stick to be the vertical fuselage of the plane. Now you can move the stick in the direction you want the plane to tilt, for example:
To make the plane to tilt away from you, push the stick away from you.
To make the plane to tilt to the right, push the stick to the right.
If the plane drifts away and to the left, pull the stick towards you and to the right to counteract it.
And so on. Very natural. This is sometimes called “flying the nose” because the plane reacts as if your thumb was on its nose.

Canopy out: Consider that the right control stick is attached to the tail of the plane, and that you are balancing the plane on the top of the stick. Now move the control stick just as if the plane really was balancing on its tail, for example:
If the plane falls away from you, push the stick away to re-balance the plane.
If the plane falls to the right, push the stick to the right to re-balance the plane.
And so on. Again , very natural. Most people can balance a stick on their finger, so they should find Mode 4 wheels-in hovering very easy. This is sometimes called “flying the tail” because the plane reacts as if your thumb was supporting it on its tail.

Inverted Flight
In inverted flight the actions of the throttle and ailerons remain the same as for normal flight, but the rudder and elevator controls are reversed. In Mode 2, each stick has one control reversed and one normal. In Mode 4 the left stick remains normal, and both controls on the right stick are reversed. For me this is easier to remember, rather than trying to remember which of the two controls on each stick is reversed and which stays the same, as you have to for Mode 2. In a way similar to hovering, you fly the nose of the plane when it is approaching you, and fly the tail when it is going away, and the main controls for doing this are both on the right stick, in Mode 4.

Benefits of Mode 2
Some people say that Mode 2 is better because the right stick acts like the joystick in a full-sized aircraft. While this is true, I believe it is irrelevant. Friends of mine who fly both RC Mode 2 and full-sized planes tell me that the experiences are quite different. Maybe if RC pilots used foot pedals and separate throttle levers, and had seats that always oriented them in line with the aircraft, there might be a case. But most of us don’t fly full-sized aircraft anyway.
Another argument in favor of Mode 2, in most places in the world, is that you can fly other people’s planes and they can fly yours. Again, this is true, and is a valid argument. However, if more transmitter manufacturers would provide the facility for switching Modes, as some already do, this would be a non issue. For me this is actually a benefit. I hate flying other people’s planes ever since I smacked a friend’s plane into the trunk of a tree, pretty much wrecking it, the plane, not the tree.
So now I have an excuse not to fly other peoples’ planes. But if I want someone else to fly my plane, I just switch my transmitter to Mode 2 and hand it to them.
What about three channel throttle, elevator and aileron planes? Here I don’t think there is much to choose between Mode 2 and Mode 4. Now the ailerons play a more active role and it could be argued that they would do better on the dominant hand, Mode 2 for righties. At the same time some pylon racing people have told me they have the aileron on the left stick (Mode 4) to maintain a good separation between the bank and yank phases of a pylon turn.

It has been said that focusing on rolls, hovering and inverted flight is biased, and surely there are other maneuvers for which Mode 2 is better than Mode 4. I am yet to find them.
Perhaps the biggest case for Mode 2 is that it is what most people have learned from other misguided souls, and changing to any other convention would be very difficult to do.

What about Mode 1?
The difference between Mode 1 and Mode 4 is that the entire sticks are swapped. Because of this, Mode 1 enjoys all of the benefits of Mode 4, except one. The rapidly-changing controls for rolling or hovering are the elevator and rudder, so they should be assigned to the dominant hand.
Most people are right-handed, so Mode 4 is better for them. Left-handed people would do better with Mode 1.

What about Mode 3?
I can find no redeeming properties for Mode 3.

Conclusions
Using Mode 4 facilitates a range of 3D maneuvers. If you are familiar with Mode 2 you should probably stay with it. But if you have only flown two or three channel planes with rudder and elevator on the right stick, you might give some consideration to staying with Mode 4 and putting the aileron on the left, rather than following the herd.