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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.

Aerobatic Maneuvers – Part 1 (Rolls)

April 30, 2010 Leave a comment

Tired of flying straight & level ?  I’ll describe in detail all of the wildest aerobatic maneuvers for you to try!

This will be a list of aerobatic figures that have common names. Some of these were invented during aerial combat in World War I. I have also included a short verbal description and the IAC symbol for each basic figure.

The symbols for the figures follow the rules of the FAI for depicting aerobatic figures. The figure starts at the small solid circle and ends at the vertical bar. All aerobatics figures start and end from horizontal lines in either upright or inverted flight. In aerobatics competition, most figures can be entered and/or exited from either upright or inverted flight. This affects the difficulty numbers for the figures. In general, the altitude at which the figure is entered does not have to be the same as the exit altitude. Exceptions are for instance the Cuban Eight, all full loops (regular loop, square loop, etc). In cases where the entry and exit lines have to be the same altitude, they are drawn slightly separated to better show them.

The elements used in these figures are horizontal, vertical and 45 degree lines. These describe straight flight in these directions. Solid lines describe upright flight, dashed lines describe inverted flight. Parts of loops connect these line segments (see e.g. the Humpry-Bump). Rolls in 1/4, 1/2, 3/4, etc increments up to 2 rolls can be added to the lines.

The looping portions in almost all figures have to have the same radius in all parts of a figure. For instance the quarter loops going into and coming out of a hammerhead have to have the same radius. There are some figures where this does not apply completely.

Rolls on vertical lines and on 45 degree lines have to be centered on this line to score well. Any deviation from the center results in a downgrading during a competition.

In this first post i will start explaining rolls, but come back and check later for all the aerobatic maneuvers, as i will be explaining all of them.

Rolls

Rolls can be added to most other figures to increase the difficulty factor of the figure. There are two basic types of rolls: slow rollss and snap rolls (flick rolls in european parlance).

Slow Rolls

1)

Slow Rolls 1
Slow Rolls 1

2)

Slow Rolls 2
Slow Rolls 2

Slow rolls have to be flown normally on a straight line (exception is the avalanche). The roll rate has to be constant and the longitudinal axis of the plane has to go straight. This requires constantly changing rudder and elevator control inputs throughout the roll. Hesitation or point rolls include stops at certain roll angles. The number on the base of the roll symbol describes the number of points the roll would have if it were a 360 degree roll. Allowed are 2 point, 4 point and 8 point rolls. The fraction on the arrow of the roll symbol describes what fraction of a full roll is to be executed. If no points are specified, rolling is done without hesitations. If no fraction is specified, a roll symbol that starts at the line specifies a half roll (see description of the Immelman). A roll symbol that crosses the line specifies a full roll (first figure). The second figure shows the symbol for 2 points of a 4 point roll (adding up to half a roll) from upright to inverted flight.

Snap Rolls

3)

Snap Rolls 1
Snap Rolls 1

4)

Snap Rolls 2
Snap Rolls 2

Snap or flick rolls also have to be flown normally on a straight line. A snap roll is similar to a horizontal spin. It is an auto rotation with one wing stalled. Figure 3 shows the symbol for a regular snap roll, figure 4 for an outside snap. In the regular snap, the plane has to be stalled by applying positive g forces. In an outside snap, the plane is stalled by applying negative g. In both cases rudder is then used to start auto rotation just like in a spin.