Swift Setup

Who should read this?

The information in this article is aimed at the beginner who is new to R/C Helicopters. Whilst the information may also be relevant to more experienced pilots it does not show how to setup the Swift for 3D flight. The following text contains original information written for Swift-Tuning as well as information republished with permission and based upon an original article by Nigel Fraser Ker.

Initial Transmitter Setup

In the main, the transmitter can be set up after final assembly but because the motor is so powerful it's best to configure this particular item early on.  On a general safety note, when you're about to switch on your radio gear, always* move the throttle to its lowest position and always switch on your transmitter before you power up the receiver. This prevents your servos from moving to extreme positions and also ensures that your ESC is set to zero power - you don't want to connect your battery and suddenly find that the motor is set to full throttle!  Another point to note is that electric motors can easily over-speed if they are run without a load.  Follow the manufacturer's guidelines but if you're unsure about testing electric motors without a load, run them as slowly as possible.  Do not run them up to see how fast they will go - the chances are that you will permanently damage them.

*except in accordance with the manufacturer's setup procedures

ESCs can be dangerous if they're not set up correctly so before I connect the ESC to the receiver I plug a servo into the throttle channel and test the radio gear.  This way, I can check that the ESC is definitely connected correctly.  If you have a throttle hold feature on your transmitter now would be a good time to get it working correctly, i.e. while the test servo is connected to the throttle channel.  Make sure that when you select throttle hold the test servo moves to one end of its travel and stays there even if you move the throttle stick.  This is a nice safety feature because keeping it on when you're not flying will prevent an accident if someone bumps the throttle stick.  At this stage, you don't know if this throttle setting is low or high because you haven't yet determined which way round your ESC works.  You may need to reverse the throttle channel so to set it up correctly consult your ESC manual.  Usually, the ESC will make a particular sound when you switch the power on, e.g. one for low throttle and one for high.  Different ESCs have different setup methods and because these little motors are so powerful you should follow the manufacturer's guidelines carefully.  The ESC is probably the most difficult thing on the helicopter to setup because you can't see what's going on inside.  In any case, if you have any doubts you can always contact your dealer for more information.

Throttle & Pitch Curves

One of the things you're going to do in the next section is to set up your throttle and pitch curves.  I'd like to take a little time to explain these now so that you understand what figures you're putting into your transmitter.

By now you should be aware that the throttle stick on your transmitter actually controls two separate functions - the throttle and the pitch.  If the relationship between these two controls was simple (i.e. the pitch moved the same as the throttle) then you wouldn't have needed to spend all that lovely money on expensive computer radio gear.  As you will have guessed, it's more complicated than that.  In fact you need to be able to program the transmitter so that for any given stick position, you get the correct throttle and pitch setting which will not be the same.

Why do we need separate throttle and pitch settings and what are we trying to achieve?  Well, in an ideal situation, during flight our helicopter will have a constant head speed.  You might think that all we would have to do to achieve this would be to set the throttle at a fixed value and that would be that.  However, if we want to change altitude, we have to change the pitch of the main rotor blades.  Raising the pitch will make the helicopter go upwards (because the blades are producing more lift) - lowering the pitch will make it go down.  When you change the pitch (more correctly known as the collective pitch) the amount of effort the engine has to expend to turn the blades will change too.  If we tried to fly with a constant throttle, when we increased the pitch to gain altitude the head speed would decrease.  If the head speed drops below a certain point you will lose control with unfortunate results.  This means we have to increase the throttle when we increase the pitch by just the right amount to make sure that the head speed stays the same.  This is not as easy as it sounds and requires a certain amount of fine tuning. 

The relationships between the stick positions and the settings of the throttle or the pitch are called 'curves'.  Transmitters with lower specifications often only allow you to program three points on the throttle and pitch curves.  This means that you can only program the transmitter to give a certain throttle setting for low, middle and high stick positions and likewise for pitch (the transmitter will automatically 'draw' a straight line between these three points so that you get a smooth transition between them).  More expensive transmitters have a 5, 7,13 or even 17-point curve capability and top-of-the-range models even draw nice smooth curvy lines between the points.  All this allows the pilot to set up his helicopter with great precision but don't worry about getting too fancy yet - perhaps leave it until you're competing at the World Championships!

For our purposes a 3-point curve will be sufficient but a 5-point curve is better. 

If your transmitter only has a 3-point curve capability then you can forget about the quarter and three quarter stick positions.  For a simple hovering curve like this it really doesn't matter too much since the curves we are looking for are fairly simple.

Finally, I need to say a word about governors.  If you have a brushless motor the ESC may have a neat feature called 'governor mode' or something similar.  This allows you to determine what your head speed is going to be electronically rather than by using the throttle curve.  It's a bit like the cruise control on a car.  Refer to your ESC's instructions on how to set up the governor mode.  Once done you don't have to worry about accurately setting up the throttle curve to achieve the correct speed over a variety of different pitch settings.  Instead, and depending on your ESC, you will probably just use the throttle curve to determine the head speed and it will look something like this...

Throttle curve for a governor on a Futaba T9ZHP

Final Transmitter Setup

This is perhaps the area that beginners find most difficult.  Computerised transmitters are necessarily quite complicated.  They are all setup in different ways and the manuals are often written with the assumption of some prior knowledge.  I will try to give you an idea of what you're aiming to achieve and hopefully, by running through everything in a logical manner, we will be able to get your helicopter setup correctly.

If you are unsure of what you're doing with your transmitter perhaps the best way to start is to make sure that you have a completely new helicopter model setup in the active memory of the transmitter.  You'll have to read your transmitter manual to find out how to do this but clearing all the data and starting afresh is often called a 'Reset'.  You only need to reset the model you have in memory, not your whole transmitter.  If your transmitter is used for other models be careful not to erase the model memories you have allocated to them.  Make sure you are using a helicopter model type with CCPM mixing.  You should also ensure that your transmitter modulation setting is the same as your receiver, e.g. PPM or PCM depending on what receiver you have.

I will now give you some simple pointers as to what to set up.  It's hard to do this in detail without writing an entire book on the subject so I'll keep it short.  Before you start, make sure the motor is disconnected.

One question you may be asking yourself is "Why does the pitch curve start at 50%?".  This is because as a beginner you will be using only half of the total pitch range, i.e. from 0° to +11°.  You will expand your pitch range, eventually up to its full travel (i.e. -11° to +11°), when you become more experienced.  Negative pitch gives negative lift  which is effectively positive lift if you happen to be flying inverted, e.g. when you are at the top of a loop.  More about this in the aerobatic and 3D article.

Receiver Connection

Having mounted the receiver it is now time to connect up all of the electrical equipment. In this article I will cover set up when using a JR transmitter. I will also include a table which shows how to achieve the same setup using a Futaba transmitter. In the following Channel assignment discussion all references to servos are done from a point of view above and to the rear of the Swift.

First let's list out the various channels available on the receiver and what should plug into it:
(JR Radio, 120° swashplate selected)

• Channel 1: electronic speed controller
• Channel 2: Servo connected to right of the swashplate
• Channel 3: Servo connected to the center rear of the swashplate
• Channel 4: gyro
• Channel 5: gyro gain (if applicable)
• Channel 6: Servo connected to left of the swashplate
• Channel 7: Voltage monitor

The tail servo plugs directly into the gyro.

Futaba channel assignment:
(swashplate type : SR-3):

• Channel 1: Servo connected to right of the swashplate
• Channel 2: Servo connected to the center rear of the swashplate
• Channel 3: electronic speed controller
• Channel 4: gyro
• Channel 5: gyro gain (if applicable)
• Channel 6: Servo connected to left of the swashplate
• Channel 7: Voltage monitor

The tail servo plugs directly into the gyro.

 

Tail Rotor Setup

Having plugged in all of the servos and the gyro it is time to power up your transmitter and plug in a receiver pack to power the helicopter radio system and gyro. The first task is to setup the tail rotor and gyro.Setting up the tail system is not complicated but it is an area that the beginner to helicopters often gets very confused over. So before starting on the technical stuff let's quickly overview what we want the tail to do when we push the transmitter stick one way or the other.

When pushing the tail rotor transmitter stick to the left the nose of the helicopter should rotate to the left. Similarly when pushing the tail rotor transmitter stick to the right the nose of the helicopter should rotate to the right. I have seen in the past many beginners set this up incorrectly such that "left stick" on the transmitter causes the tail rotor to rotate to the left. This is incorrect. The transmitter stick should be programmed such that you are controlling the nose of the helicopter and which way it rotates.

With that clear, let's now look at how we understand which way the tail rotor needs to move in order that we get the desired effect at the nose of the helicopter. Below are two pictures which show the tail rotor in two different orientations. The first picture illustrates what the tail rotor will look like when you are commanding the helicopter to rotate to the right. The second picture illustrates what the tail rotor will look like when you are commanding helicopter to rotate to the left.

Before looking at this in more detail I use an analogy in order to understand how to set up a tail rotor. This analogy involves thinking of the tail rotor blades as a rudder on a boat. If you place the tail rotor blades in a vertical plane (as shown in the pictures) the lower tail rotor blade can be thought of as the rudder in this analogy.

Taking the pictures one at a time, the first picture is showing "right stick" and we are attempting to set the tail rotor up such that the model will rotate its nose to the right. If you now look at the lower tail rotor blade you can see that if this was a rudder on a boat the tail would be moving in the direction indicated by the red arrow at the bottom of the picture. If the tail is moving to the left (as shown) then the nose of the helicopter will be rotating to the right. Therefore we can see that we have set this up correctly.

The second picture is showing "left stick" and we are attempting to set the tail rotor up such that the model will rotate its nose to the left. Looking at the lower tail rotor blade again you can see that if this was a rudder on a boat the tail be moving in the direction indicated by the red arrow at the bottom of the picture. If the tail is moving to the right (as shown) then the nose of the helicopter will be rotating to the left. Again we have set this up correctly.

"Right Stick" - Tail goes left, Nose goes right.

 

"Left Stick" - Tail goes right, Nose goes left.

Gyro Installation and Setup

Having got the tail rotor to react correctly to inputs at the transmitter we are halfway to getting the tail set up. The next task is to make sure that the gyro is also acting correctly.

First let's understand what the gyro is there to do. The gyro is to stabilise the tail and its job is to make sure that the helicopter will not rotate unless you command it to do so. The gyro detects rotational movement and corrects this with an opposite command to the unwanted rotation. This therefore holds the tail steady. Unfortunately gyros are not smart enough to work out for themselves which way they need to move the servo in order to make the correct command input. To explain this further what we are attempting to do is to make sure that if the helicopter rotates to the right (perhaps due to a gust of wind) the gyro should be sending to the servo the correct command for left rotation...... therefore arresting the unwanted right rotation.

Once we have set this up the gyro will work correctly. If we set this up incorrectly then the following behaviour will be observed. .... as the helicopter lifts off it will spin uncontrollably.

The reason for this uncontrollable spin is that the gyro will detect (as an example) unwanted rotation to the right. It sends to the servo what it thinks is the correct command to add some left tail rotor input. Unfortunately this is set up incorrectly and the gyro actually sends right tail rotor input. This makes the helicopter rotate even faster to the right, which the gyro then tries to compensate for by giving a bigger left command input. Again because this is set up incorrectly it actually inputs even more right tail rotor. Hence the uncontrollable spinning if a gyro is not setup correctly.

Fortunately it is very straightforward to set this up correctly on the bench long before you attempt to actually fly the model.

The gyro will either be acting correctly or incorrectly. If it is acting incorrectly then fixing the problem is a simple case of "reversing" the gyro. Reversing the gyro can be achieved by one of two methods depending on the make and model of gyro. Some gyros have a reverse switch or can be programmed. Other gyros are just turned upside down in order to reverse their direction. Consult your manual in order to ascertain how you reverse your gyros direction.

In this build I am using CSM560 gyro. This gyro allows you to reverse its direction through it's software programming.

So how do we work out if our gyro requires reversing?
With the model powered up using a receiver battery hold the tail of the helicopter and give it a sharp movement to the left. As you do this you need to be looking at the servo to see which way it moves. The servo will move because the gyro has detected an unwanted movement and is attempting to correct it. We are simulating an unwanted rotation of the nose of the helicopter to the right (tail to the left). Therefore the gyro should be inputting a left tail rotor command in order to arrest this unwanted movement. Repeat the sharp movement several times until you are sure which way the servo is moving. Now go to your transmitter and input left stick. If the servo (when you input left stick) is moving the same direction as when you were making your sharp unwanted movement then your gyro does not require reversing. If the servo movement is different (opposite) then you do need to reverse the gyro.

The last item to check when setting up the tail rotor is that there is no binding at either end of the tail rotor servos movement. This is checked by commanding full left stick and then full right stick at the transmitter and looking to see if the servo is binding at the extremes of movement.

If there is binding then this needs to be removed. This can be achieved by two methods. The first method is that many gyros allow you to adjust how much the servo can move. This could be via an adjustment pot on the gyro itself, or it could be by using the programming facilities of the gyro (depending on the gyro). The second method is to reduce the length of the servo horn. Adjust as necessary to remove the binding.

Once you have removed any binding from the tail rotor (and completed all the previous steps) the tail system should be set up and ready for flight.

If you have a Futaba GY401 then please see this detailed setup article.

eCCPM Setup

The next step is to get the collective and cyclic servos working in the correct orientation. The Swift is a ccpm helicopter and therefore the mixing for the swashplate is done in the transmitter. Unfortunately this means that setting up the servos for collective and cyclic can be a little bit mind-boggling for the beginner. Therefore I have created the following process which should work if you follow each step exactly. This process works from any starting point and should leave you with a correctly orientated set of collective and cyclic servos.I have written the following steps for use with JR transmitters. The process in principle should work for other transmitter types but may require a little translation to function correctly. At the end of the process are some screen shots from a JR PCM 9XII showing the various screens on the transmitter.

Firstly we need to label the servos so I can refer to them in the process. Viewing the helicopter from the rear :

Servo	Number	Channel (JR)
Servo connected to left side of swashplate	1	CH 6
Servo connected to right side of swashplate	2	CH 2
Servo connected to center line of swashplate	3	CH 3

1. Consult your transmitter manual and set your swashplate type to 120° configuration.
2. Power on your radio system using a receiver pack, we do not want the motor to start during the setup
3. Centre both transmitter sticks
4. Switch to the servo reversing menu on your transmitter
5. Push elevator stick forward, if servo 1 and 2 move in opposite directions (one up, one down) reverse servo 1
6. Push elevator stick forward, if servo 1, 2 and 3 all move the same direction (all up or all down) reverse servo 3
7. Switch to your swashplate mixing menu
8. Push the elevator stick forward, if the swashplate tilts backwards change the elevator mixing value to -60
9. Push the Aileron stick left, if the swashplate tilts right change the aileron mixing value to -60
10. Push the collective stick upwards, if the swashplate moves downwards change the pitch mixing value to -60

 

The last thing to do in setting up eCCPM is to set the values in the swashplate mixing menu. The values you set here will depend on how long your servo horns were. My servo horns in this build are set to 15 mm from the centre of the servo to the pushrod on the servo horn. My swashplate mixing is set to 60 for elevator and aileron. My pitch is was initially set to 80. I had it set to 80 so that I could over pitch the machine for punchy manoeuvers. Good starting values would be 60 for aileron and elevator and 60 for pitch. These values will give you a reasonable throw on the swashplate for cyclic and around about +/-9° of pitch on the blades. I would recommend checking your pitch range using a pitch gauge to make sure that you are working within an acceptable pitch range of approximately +/-9°. After some more flight testing I increased the elevator and aileron values to 80 to give me much faster roll and flip rates. Pitch was decreased to 70 as there was a little too much throw for my current setups which are 4S/5S. I may go back up to 80 for pitch when I move onto more powerful 6S setups but for the moment 80 is too much. This completes the setup of the cyclic/collective servos.

Starting the Swift for the first time

Okay, this is it - we're going to start up our nice gleaming new helicopter.  The first time you do this it's a good idea to do it without either the main or tail rotor blades on.  Here's your checklist...

• Check that the transmitter battery is charged and that you have installed (but not yet connected) your flight battery
• Fit a training undercarriage if you are not an experienced pilot.
• Carry out your normal safety checks
• If you're flying near other r/c fliers (near means within a two mile radius to be safe!) make sure you're not on the same channel.  This is for your safety as well as theirs.  If you are flying at a club or at a fly-in, use the frequency control system.
• Switch on your transmitter and check the battery voltage.
• Hold the blade grips firmly and plug in your flight battery.  If your ESC has a switch, switch it on.
• Wait for your gyro and speed controller to initialise.  Don't move the helicopter at all while it is doing this.

I will now go through each control and describe what is supposed to happen on the helicopter if you are using a Mode 2 transmitter.  This is the more common type but if your transmitter is Mode 1 (as is the one shown in the instructions) then the throttle/pitch control will be on the right-hand stick and the elevator control will be on the left-hand stick.  For more details about transmitter modes see this article.

Important!  Make sure that 'Idle Up' or 'Stunt' facility on your transmitter is disabled or inhibited before proceeding!  If you can't disable it, make sure that any switches that control it are in the 'Off' position.  You should get into the habit of putting the switches to their 'start-up' positions before every flight.

If all those tests worked okay then well done!  You're getting there.  In theory you're ready to fly!  

Range Check

It is very important to perform a range check before you fly the model.  Disconnect the motor before you try this.  You should refer to manufacturer's instructions and your national governing body's guidelines for details on this test but, as a guide, I would recommend that you should be able to retract the antenna and walk about 25 metres away with no problems/interference, etc.  The British Model Flying Association's handbook says that you should "Look for a minimum range of around 50 metres with the transmitter aerial down."  However, this test was not written for receivers designed for small electric models and you may find that 50 metres is a 'tall order'.

Radio Interference and Range Problems

It's worth saying a few words about radio interference - a problem that is particularly common in electric models.  The small 'micro' radio receivers that are most often fitted to electric aircraft typically do not have as high a specification as their larger cousins and must therefore be tested carefully and treated with some caution.

• Carry out a regular range check of your equipment
• Ensure that the crystal is properly seated in the receiver
• Run the receiver aerial as far away from the other electrical devices on the helicopter as possible, especially the motor and speed controller
• Be very careful with transmitter and receiver crystals - they are very sensitive to mechanical shocks and care should be taken not to drop them
• If possible use high quality dual conversion, PCM or Berg technology receivers

Things that can cause radio reception/interference problems are:

• Loose metal-to-metal contacts on the helicopter
• Poorly sited receiver antennas
• Faulty radio control equipment
• Nearby radio transmission masts or microwave transmissions over the flying field
• Poorly suppressed commutator contacts on brushed motors
• Metal objects such as the frames of metal buildings, metal fences, etc.  Even buried metal objects have been known to cause problems
• Faulty or damaged crystals in your transmitter or receiver
• Nearby mobile telephones

If you really can't get rid of your radio interference problems, you may need to consider upgrading your receiver.

Flying the Swift for the first time

Iit would be a good idea to make your first few flights in calm conditions.

Here's a useful tip.  Whatever flight batteries you are using, it's a good idea to make sure that the terminals can't accidentally short circuit.  A good way to prevent this happening is to get a couple of inch-long pieces of r/c fuel tubing and when you disconnect the battery, slip the fuel tubing over the battery terminals.

The blades must not be too tight or too loose.  The Swift prefers a fairly tight blade, tighten up the main blades so that they will move with moderate pressure, they should not be so tight that they require a lot of effort to move.  The tail blades should be just loose enough to fall under their own weight when the tail is slowly rotated.

Now we are ready to start up again.  Remember to switch on your transmitter first, make sure the throttle is low, all the switches are in the correct positions and then plug in the flight battery with the helicopter on the ground.  If your ESC has a switch, switch it on.  Wait for the gyro and ESC to initialise before you move the helicopter.  Then...

1. Engage the throttle hold
2. Place the helicopter in an open space and stand about 3 metres away from it.
3. Test all the flight controls
4. Make sure the throttle is at the low position and disengage the throttle hold.
5. GRADUALLY open the throttle.  The motor should start up (possibly a little more suddenly than you expected), the main rotor blades should start to turn clockwise (looking from the top) and as the tail rotor goes round, whichever is the bottom blade should be travelling forwards.  GRADUALLY keep increasing the throttle and watch the main rotor blades.  Don't try to take off yet.  Ask yourself the following questions...
   
   • Is the rotor disk leaning in any particular direction? If it is noticeably leaning left or right, try adjusting the aileron trim. If it is noticeably leaning forward or backwards, try adjusting the elevator trim. If this doesn't work, make sure that your swashplate is level.
   • Is the helicopter vibrating excessively? If it is, stop the motor, engage the throttle hold and check that your main rotor blade grips are not too tight, that your blade grips are correctly located (i.e. pulled out correctly) and that your tracking is not very different on the two main blades. If none of these work then your blades may be out of balance. Balancing and tracking the blades is covered in the 'Main Rotor Adjustment' section of the manual. Check that your flybar is also balanced properly and that the paddles are the same distance away from the axis of rotation.
   • Is the rudder working correctly? With the blades rotating at a moderate speed, try moving the rudder from left to right. You should see the tail try to move right and left. To be clear, when you move the rudder stick to the left, the nose of the helicopter should try to move to the left.
6. Keep increasing the throttle and keep testing the controls. As you start to lift the weight off the skids, if the helicopter suddenly starts to rotate on the spot, stop the motor and disconnect the battery. The probable cause of this problem is that the gyro 'sense' is wrong (rather than correcting any small movements it detects, it is exaggerating them). Check the gyro manual and correct.

If all is well, as you increase the throttle, you should eventually get into the air.

 

 

Appendix 1 - Safety Checks

These are the safety guidelines that I use for electric helicopter flying and are based on those issued by the British Model Flying Association.  However, you should always refer to your own national association and rules for local guidance. 

A. CHECKS BEFORE DAILY FLYING SESSION

1. Check all ball links for slop and change as necessary.
2. Check that all rotor blades are in good condition with no damage apart from minor tip damage.
3. Check for loose or missing nuts and bolts.
4. Check that there is no backlash in the drive system apart from gear backlash which should not be excessive.
5. Check that servos are secure.
6. Check that the receiver aerial is secure and in good condition with no chafing or damage.

B. CHECKS BEFORE EACH FLIGHT

1. If a helicopter suffers damage or a heavy landing, re-check all of (A) above.
2. Check all controls before starting especially for binding links or slowing of servos.
3. Re-check controls at high rotor rpm just before lift-off.
4. Check for vibration and eliminate before flight.
5. Check main rotor blades for true tracking in hovering flight.
6. Check that the receiver aerial cannot become entangled with any moving or rotating part.
7. Check that the flight battery is properly secured and in good condition.
8. Double check that all switches on the transmitter are in their correct positions before EVERY flight.