Posts Tagged ‘aileron’

Learning to torque roll an RC airplane

May 19, 2010 Leave a comment

Hi! We’re back to the technique lessons! This time i’ll focus on the amazing torque rolls and how you can achieve it with success.

Torque Roll

Torque Roll

You’ve seen those super low hovers and torque rolls in demonstrations and in model magazines, and you’ve probably wondered just how they are done. Super human flying ability? Hi-tech gyro gismos and big, expensive models? Certainly, you say, torque rolls can’t be in the flight plan of a sport modeler who likes to fly normal sport models can they? Well, actually, they can.

It takes practice…

It’ll take practice, of course, and plenty of it. But saying, “just practice” is like saying if you want to paint like Picasso, just start painting. The major stumbling block for most pilots is knowing just what it is you’re supposed to be practicing. And then there’s the plane. What kind of model do you need? Maybe you’re a sport modeler and don’t want an expensive “TOC” model…if that’s what it takes.

Relax. Because besides lots of practice and a good plane, learning to Torque Roll takes one more thing: a plan. And we’ve got it right here.  So read on and we’ll let you in on how the pros got to be pros at it. It’s still going to take practice, but here’s what to practice first and what to practice with.

The Right Plane

No, it doesn’t take an expensive “TOC” model. It doesn’t even take a scale aerobatic plane. It does take a plane with some specific qualities though, but you can find these qualities in some fun, economical sport models.

The plane has to have a lot of elevator and rudder authority. This is important since, while in a hover, you need to be able to maintain pitch and yaw control with the only airflow over the tail coming from the prop.

Great power to weight ratio is a big help, too. While learning, and even if you are a torque roll master, at times you will need to “get out” in a hurry. The safest direction to get out is naturally the opposite direction of our nemesis, the ground. To hang on the prop and to blast out vertically, you need great, reliable power.

The catch-22 of torque rolling is that practicing up high gives you the altitude you need to recover when you get crossed up, but it’s a lot harder to do. Learning torque rolls lower to the ground is much easier, because you can see much better and make corrections faster, but one mistake and it’s that old nemesis again…CRUNCH!! So try to practice with as much altitude as you can.

Step 1

Like learning to ski, you need to know how to fall down and get back up first. You WILL make mistakes, even when you have it mastered. So, don’t worry about how to control the torque roll yet. Concentrate on learning to catch the model and fly out of any mistake without losing altitude, regardless of the attitude the model falls into. This is the key to the torque roll.

How to do it: At a safe altitude, pull the model vertical at about 1/4 throttle and begin to hover. Use just enough throttle to pull vertical, but not enough to sustain a hover. Let the model begin to fall out- it may fall to the side, the top, bottom or any combination. Practice catching it with the correct elevator and/or rudder input, and get the throttle in it. Focus on flying out level. After you start to get the hang of it and react faster, fly out vertical.

Trickiest Part: Don’t get confused and give the wrong input. Be careful, especially when the model falls with the nose toward you. That’s why we start at a nice safe altitude.

Step 2

You’ve now crossed the biggest hurdle to learning the torque roll. You can recover, no matter which way the model falls out. You have confidence that you can save the plane every time. Now you can concentrate on two new things. First, work on reacting with the correct rudder and elevator inputs to keep the model vertical. (The good news is Step 1 has already sharpened your orientation and reaction skills.) Second, learn to “fly” the throttle stick to maintain altitude in a hover but not climb or drop.

How to do it: Now it’s time to bring it down to a lower altitude. Start at about 25 feet, low enough to see the model and still high enough to give you a little reaction time before terra firma. Again pull to vertical, only this time add a little more power so that the model hangs motionless in the air. Once you’ve got the throttle figured out, concentrate on flying the rudder and elevator to keep the model vertical. Don’t worry about ailerons, they aren’t going to do much while you’re hovering. This is simply a balancing act, like riding a unicycle. The model may hover or it may begin to torque roll to the left. Don’t worry about rolling, this happens on its own and you don’t need to make it roll. The model will begin to roll once it is very close to dead vertical. The better you can hold the model vertical, the faster it will torque roll.

Hint: Choose a calm day to practice. Wind makes torque rolls much harder. You will also need lots of control surface throw to maintain control. Use as much as you can get, similar to a “3D” set-up if possible. While you’ll need this much control at times, it also makes it much easier to over-control the model, so use some expo. I suggest about 25% on rudder and 40 to 50% on elevator. Now you’ll have the control power when you need it, but a soft feel around neutral so you won’t over-control when making little corrections.

Trickiest part: Learning to keep up with the model’s orientation as it rolls to give the correct elevator and rudder inputs. It takes time to get good. One wrong input and the model will fall out, but you know how to fly out of a mistake, so set up and try again. Also don’t over-control. Even too much of the right correction will make you fall out. Flip back to low rates as the model falls out so you don’t over control and stall the plane. Use that expo feature in your radio.

Once you’ve got the hang of it, try backing the throttle down a few clicks as you are torque rolling and slide the model down closer to the ground. And that, in a nutshell, is just about it. So now that you’ve got a plan and you know what kind of plane, all that’s left is practice, practice, practice…

You’ve seen those super low hovers and torque rolls in demonstrations and in model magazines, and you’ve probably wondered just how they are done.

Super human flying ability? Hi-tech gyro gismos and big, expensive models? Certainly, you say, Torque Rolls can’t be in the flight plan of a sport modeler who likes to fly normal sport models can they? Well, actually, they can.

It takes practice…

It’ll take practice, of course, and plenty of it. But saying, “just practice” is like saying if you want to paint like Picasso, just start painting. The major stumbling block for most pilots is knowing just what it is you’re supposed to be practicing. And then there’s the plane. What kind of model do you need? Maybe you’re a sport modeler and don’t want an expensive “TOC” model…if that’s what it takes.

Relax. Because besides lots of practice and a good plane, learning to Torque Roll takes one more thing: a plan. And we’ve got it right here.

So read on and we’ll let you in on how the pros got to be pros at it. It’s still going to take practice, but here’s what to practice first and what to practice with.

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.

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.

Beginners’ Guide

April 30, 2010 Leave a comment

First Model

Some people consider a glider as the obvious choice for the first model. Although a glider normally flies slower and is supposed to be more forgiving, I think that’s just a matter of taste. Being a skilled glider pilot doesn’t necessarily mean being also a skilled powered aircraft pilot and vice-versa.

Assuming that a powered model was chosen, the beginner is advised to start with a so-called trainer. This type is usually a high wing aircraft model with nearly flat bottom airfoil that produces high lift, permitting slow landing speeds without stalling. It also has some dihedral angle to give a good lateral stability.

However, a flat bottom high wing with dihedral is more sensitive to crosswind gusts, so the first flights should be done during calm weather. A beginner should avoid wings with too sharp leading edges, as it will worsen the stall characteristics.  A well-rounded leading edge is therefore preferable, as it better conveys the airflow onto the upper wing surface allowing higher angle of attack at low speed.

A trainer model should not be too small, as it would be difficult to assemble and maintain and would be more sensitive to strong winds.  It should not be too large either,  as it would be difficult to transport, require a larger flying field and
would be more expensive. A reasonable size is about 150cm wingspan (60 in) with a high aspect ratio, which means the wingspan being about 5.5 times the wing chord. A square wing is advisable, as it distributes the weight of the aircraft evenly over the entire surface of the wing. In order to allow a reasonable low landing speed without stalling, the wing
should not be greater than about 60g/ (19-oz/sq. ft). Wing loading is the aircraft’s weight divided by the wing area. Some degree of wing washout also improves the stall characteristics.

The basic parts of a trainer model:

Engine – provides the power to rotate the propeller.
Propeller – (also Prop) is attached to the engine’s shaft to convert rotational motion into thrust and speed, which depends on the Prop’s diameter, pitch and the Engine’s power.
Spinner – streamlined part that covers the end of the Prop shaft.
Fin – (also Vertical Stabiliser) provides directional stability (stability in yaw).
Rudder – movable part fitted to the Fin’s trailing edge, is used to change the aircraft’s direction.
Stabiliser – (also Horizontal Stabiliser or Stab) provides longitudinal stability (stability in pitch).
Elevator – movable part fitted to the Horizontal Stabiliser’s trailing edge, is used to make the aircraft climb or dive.
Ailerons – movable parts on both sides of the wing, are used to make the aircraft roll about its fore – aft axis. When one aileron moves up the other moves down.
Wing – provides the aircraft’s main lifting force.

One may build a model aircraft based on drawings (plans). This requires some building skills and also time and effort to find out and gather the materials needed for the construction. An easier approach (albeit more expensive) is buying a kit of parts. There are many kits on the market with different levels of prefabrication depending on their price.
The cheaper kits have most of parts included, but some pieces come either pre-cut or printed on sheets of wood, so the builder is expected to do some extensive job, such as to cut out the fuselage formers and wing ribs, glue the parts together, apply the covering material, etc.
For those who are not so keen on construction, there are almost ready to fly (ARF) kits with an extensive re-fabrication, requiring one or two evenings to assemble. There are also ready to fly (RTF), which normally come complete with the power plant and some of them even with the radio pre-installed.

First Flight

It’s highly recommended to have an experienced instructor beside you during your first flight. However, it is not impossible to get succeed by doing it alone. Maximum wind speed recommended is 5-8 Km/h (3-5 mph) including gusts.

Check your plane’s CG location with empty fuel tank (if you are using a combustion model) or with batteries (if using an electric model) by supporting the model with your fingertips underneath the wings. Find the position where the fuselage gets level or its nose is pointed slightly downwards. Remember a golden rule: a plane with a CG a bit forward to it’s ideal location will fly badly, but a plane with a CG aft it’s ideal location will fly once… So, if you are not sure about how to exactly put your CG, just make sure it is more forward than aft. Within the first flights when you try to fly leveled you will notice by it’s flight characteristics and you can make small corrections on each new flight.

Transmission range check should be performed on the ground before the flight. This is usually done with the Transmitter aerial collapsed (this is not applicable for 2.4Ghz radio systems). The control surfaces should respond without glitch at a distance of about 80 meters (263ft). This distance is only an approximately guide line, as the actual range may vary depending on the environment.
The effective range may only be half of this value if located at mountain bowl site or close to a public radio transmitter, radar station or similar. The range may suffer adverse effects if the receiver aerial is close to metal parts or model components reinforced with carbon fiber. Some transmitters allow the aerial to be totally collapsed inside a metal case (again not applicable to 2.4Ghz radio systems), which also may reduce the radiation. In this case the lower section of the aerial should be extended during the test. The check should be repeated with the power system running, alternating the throttle setting between idle and full-throttle.

The range will be much higher when the model is in the air, normally about 1Km or as far as one can see the model.


If you hand launch your model, throw it against the wind horizontally and straight ahead, not up.
If you take-off from the ground, taxi the model towards the wind and let the model gain ground speed before applying elevator. Once in the air try to climb at a very small angle, not abruptly upward, which would cause loss of airspeed and stall.

The model is more sensitive to the motor torque effect during the relatively low take-off speed and may begin to turn left (or right). Use the rudder or ailerons to prevent the model from turning during the climb stage, otherwise the model may initiate a spiral dive.

Don’t try any turns until the model has gained speed and reached a “safe altitude”. Be very gentle with the controls and practice gentle turns high in the air before you try to land. To prevent losing altitude when turning the model, just give little up elevator at same time you make a turn.

Try to keep the model in sight and do not fly too high or too far away. You may reduce the throttle while high in the air so you may get an idea how the model behaves at low speed – try to glide it while high and use just a bit of elevator to keep the nose leveled – even thought initially you will feel it is too slow and it may fall, just keep doing it so you have a real feel of how slow it can fly (as you have the model high in the air with slack to recover if something happens). This will give you an idea of the kind of speed you will use when approaching for a smooth landing (which will NOT happen on the first times… – you have been warned).

To prevent getting confused about which way to turn when the model flies towards you, turn your back to the model slightly while keeping watching it, so you can imagine “right” and “left” from the model’s point of view. At this stage, you should have already practiced with a good computer flight simulator and you should be already comfortable with this situation. If not, better to spend a few more hours on the simulator if you don’t want to crash your expensive plane.

Some trimming may be needed in order to reduce or eliminate roll, bank and/or pitch tendencies. A flat bottom wing often tends to “balloon” up into the sky, keeping climbing when full throttle is applied. This may be reduced during the flight by adjusting the elevator trim or by reducing the throttle. In worst cases it may be needed to increase the motor’s down-thrust angle and/or decrease the main wings incidence angle.


Reduce throttle to about half or even less (depending on the power and torque of your power plant) so you have to slightly pull up the elevator to keep the altitude. Turn the model towards the wind and let the model sink gradually towards the landing area by easing the elevator.

During the last fifteen to twenty meters (45 to 60 feet) of descent, (which depends on the model’s characteristics) you should idle the throttle. The model will start sinking at a higher rate now. Try to keep the model in a shallow dive and don’t use the elevator to gain altitude or to prolong the flight at this stage, otherwise stall is likely to occur.
Just keep a slightly downward attitude throughout the final approach in order to maintain the airspeed.
The higher the wing loading, the steeper the approaching angle may be. However, it is not recommended approaching angles greater than 45 degrees.
If you notice that the model is sinking too fast or is too low to reach the landing field – just increase the throttle first before applying elevator to maintain or gain altitude to prolong the flight or to repeat the landing approach.
Pull up the elevator slightly about 30-60cm (1-2 ft) before the touch-down so that the propeller or nose gear don’t hit the ground.

Be prepared to repeat unsuccessful landings several times, since it’s often a matter of trial and error before one gets used with how the model behaves. If you are using a flying field with grass around the track (highly advisable), on the first tries just worry about the landing approach. Don’t try to land in a specific spot, avoid turns when the model is flying low or at low speed. Just let your model glide into the ground straight-ahead. With time and more experience, you will get better and better an soon will be landing exactly where you want. Even experienced pilots sometimes have hard landings, as this is the most difficult maneuver.

Avoid the proximity of buildings, roads and electric power lines. Don’t fly close to or towards people and animals.
The bigger the field for your first flight, the greater will be your chances for success. And remember, if the weather conditions are not adequate for your first experiences, control your excitement and come back later when the weather is better. This is a great way to prevent mistakes that will cost you a lot of money in repairs.

It’s also advisable to join the nearest model aircraft club there you may meet experienced fliers who can provide lots of useful tips and hints.

Good luck!