stokke
Well-Known Member
To get a perfectly behaved bird you will need a perfectly set up head. In this guide I will cover everything which has to do with mechanical and radio adjustment concerning the head setup.
This will be covered:
The guide is intended for:
What's being used for demonstration:
What tools are needed:
Your average standard RC equipment.
Pitch gauge and ball link pliers (digital gauge is not necessary, a standard gauge will do fine).
A swash level tool (remember to get one that fits your heli size).
Let's get started
The guide will cover setup for the 3GX FBL system. You may find it enriching even if you have another FBL system or a flybar helicopter, but you cannot use it as a "step by step".
Power on your transmitter, enable THROTTLE HOLD. Power up your helicopter in DIR mode; hold the setup button on the 3GX unit while plugging in the battery, let go of the button when the first LED's start to light up.
The 3GX should enter DIR mode, indicated by a constant STATUS LED and a constant DIR LED.
Your transmitter should have no sub trim enabled on these channels; PITCH, AILERON and ELEVATOR.
Set your sticks to center position. You can also enter you monitor function (if you have this on your transmitter).
Sticks in center position.
When confirming center stick position in the monitor function, make sure PITCH is at 0%
Leave sticks centered during the entire 90° process.
Plug your servos into the ELE, AIL and PIT ports of the 3GX unit. At this point it does not matter what servo goes where.
Look at what general direction the servo arms are pointing, this is what we're trying for.
Get out your servo arms.
Again, remember to take out any sub trim you might have had.
Now swap the servo arms/horns around until you get one that sits as close to 90° as possible. You can also swap servos around, there is no defined function for each servo yet.
Trying servo arms. This is close but I can do better.
This one was worse then the previous.
Perfect!
You may not be able to get it perfectly 90°, but you should swap around until you get as close as possible.
Mine turned out like this.
After this point the servos function is defined, which mean you should not loose track of what's what. If you lined up yours as I did, your order is like this; ELEVATOR far left, PITCH in the middle, AILERON to the right.
Disconnect the servos. Again, remember what's what.
Connect the servos back in, this time to their designated ports. AILERON servo into AIL port etc.
In this step we will use sub trim to get a perfect 90°.
Find your sub trim menu.
Line up all the servos. Use a ruler or something to make them sit parallel besides each other. Then use a ruler as a guide. The ruler must line up with the center holes in the servo arms.
Now the goal is to achieve all arms in parallel with the ruler - use sub trim to achieve this. When doing this you should also be aware that we do want to use as little sub trim as possible. Up to 15 steps is perfectly fine, up to 30 steps is OK, up to 50 steps is a lot, over 50 steps I would not recommend. If you are unable to achieve 90° with under 50 steps of sub trim - you should consider getting new servo arms/horns.
When you have acheived 90° on all three servos, you are done with the 90'ing of servos. You should NEVER mess with sub trim on ELEVATOR, AILERON or PITCH again - if you do, you will have to redo this entire procedure.
SUB TRIM IS LEFT AT THESE SETTINGS!
You are now done and ready to run the wiring. Before you start wiring, remember to label the servos so you remember what servo goes where.
Labeled servos.
Servos set in their designated spots.
Leveling the swash.
A level swash is key to get a stable hover and predictable flight behavior.
Put the 3GX in DIR mode again.
Center sticks (let them remain in this position during the entire leveling process).
Remove the head.
Some people use the so-called "zip tie trick" to level the swash. This method is not as accurate as with a swash level tool.
One does NOT use sub trim to achieve a level swash!
Swash level tool.
Place the tool on top of the swash.
Align the tools arms with the swash arms.
The goal is to make the swash level with the tool. Each of the three arms can be lowered or raised to achieve this.
In this case, the swash arm should be raised. Meaning that the link below should be lengthened.
BUT, one should look at all three links before adjusting. If one is higher than both the other two, this one should of course be lowered - and not the other two be raised.
Adjust length of links until you get all three points level with the tool.
Perfectly adjusted (Pitch to the left, elevator to the right).
Perfectly adjusted (Elevator to the left, aileron to the right).
The swash is now level.
If you are to adjust link lengths in the future, you will raise ALL links the same amount. E.G: you raise ELEVATOR by two turns - you also raise AILERON and PITCH two turns.
Finding 0° pitch at mid stick
Put the head back on (snap on the links as well - forgot to do this in picture).
We will now adjust the blade grip links - these are the two links which connect the swash to the main blades.
The transmitter should still be at mid sticks. The goal is to get 0° on both blades.
3GX still in DIR mode.
Get out your pitch gauge.
Position the blades parallel with the bird. One blade pointing forwards - one backwards.
Parallel with helicopter.
One blade at a time!
Measure the pitch. If you get 0° no adjustment is needed.
If you get positive (e.g. +3°) you shorten the link for that particular blade one turn at a time until you get 0°.
If you get negative (e.g. -3°) you lengthen the link.
When you have achieved 0° on one blade, you turn the rotor head 180° to get the other blade in the same position as the first. Then do the same procedure for blade no. 2.
Lengthen or shorten blade grip link depending on what pitch value you got.
You should now have 0° pitch on both blades (00.4° was the closest I got).
Finding the middle of collective range.
Blades still parallel to helicopter.
3GX still in DIR mode.
Find your "swashplate" menu.
Find the PIT value. This value adjusts the collective range of your bird (more on that later on).
Raise the left stick to highest position.
Check your pitch.
Lower the stick to lowest position.
Check your pitch.
NOW:
I got +9.3° at high pitch.
I got -11.3° at low pitch.
This indicates that my center stick position (0°) is not in the middle of it's range. The goal is to have even number above and below 0° (mid stick) - the reason being that you want an opposite but equal amount of pitch on both negative and positive during flight.
To get the best control of a bird, so-called "collective management", you want this.
SO:
If you get more negative than positive like I did (+9° / -11°), you raise the entire swash. REMEMBER, raise all swash links the same amount - and one full turn at a time. Don't mess this up
If you get more positive than negative (e.g. +11° / -9°), you lower the entire swash. REMEMBER, lower all swash links the same amount - and one full turn at a time. Don't mess this up
When the swash is raised or lowered one turn, you will have to redo the 0° at mid stick again (see "Finding 0° pitch at mid stick" further up, if you forgot).
This part is tricky, and most lightly you will not get a perfect balance between positive and negative pitch. Usually you get 1-2° off - but you should adjust until you get it as close as possible. This process takes time and focus - don't rush!
Raise or lower depending on your pitch reading.
I ended up with this, 10° at high stick.
I ended up with this, 0.04° at mid stick.
I ended up with this, -10.6 at low stick.
Adjusting collective range
Now that you found your optimal center between negative and positive pitch, you can adjust your collective range.
The range will increase/decrease relatively proportional on both negative and positive pitch when adjusting collective range. E.g. at a range value of +40 on the transmitter you might get +10° on high stick and -10° on low stick - but if you increase the value to +60 you might get +15° at high stick and -15° on low stick.
There are three things to consider when adjusting collective range:
A beginner pilot might want a low collective range e.g. +9°/-9° - this will prevent rapid climb rate and present a more docile helicopter. A seasoned pilot might want a high collective range e.g. +13°/-13° - this will give a fast and agile helicopter.
If one was to use too high a collective, one might cause binding in servos as they try to achieve a throw that is out of their range. Consult the helicopter build manual to find details on this.
The less collective range that is utilized, the more power efficient a bird you will get. It's better to increase head speed than to increase collective range.
So, decide what range you want. Set your left stick to highest position.
Look at your pitch value.
While looking at the pitch value, increase or decrease the PIT value.
Raising the value will give more positive pitch.
You can also check your negative pitch - just set your left stick at lowest position.
I'm going for +10° at high stick.
I achieved +10° at a value of +41 on my transmitter.
_____________
You should now have a perfectly set up head, the next step now will be to do the rest of the 3GX setup.
If you have questions concerning the topics in this post, feel free to comment. If you have questions related to other issues, please post in the forum.
Good luck!
This will be covered:
- Setting you servos at 90°
- Leveling your swash
- Setting up 0° pitch
- Finding the middle of collective travel
- Adjusting collective range
The guide is intended for:
- Flybarless head
- Mode 2 transmitter layout (Europe/US)
What's being used for demonstration:
- Align 450 PRO V2 3GX
- Spektrum DX7S
What tools are needed:
Your average standard RC equipment.
Pitch gauge and ball link pliers (digital gauge is not necessary, a standard gauge will do fine).
A swash level tool (remember to get one that fits your heli size).
Let's get started
The guide will cover setup for the 3GX FBL system. You may find it enriching even if you have another FBL system or a flybar helicopter, but you cannot use it as a "step by step".
- It's presumed you have some general knowledge of RC helicopters
- Safety
- Safety
- Safety
- Take off main blades when possible
- Disengage motor if possible
- ALWAYS have the transmitter's THROTTLE HOLD engaged if working on a LIVE system
- I take no responsibility for damage or injury caused by following these instructions
Power on your transmitter, enable THROTTLE HOLD. Power up your helicopter in DIR mode; hold the setup button on the 3GX unit while plugging in the battery, let go of the button when the first LED's start to light up.
The 3GX should enter DIR mode, indicated by a constant STATUS LED and a constant DIR LED.
Your transmitter should have no sub trim enabled on these channels; PITCH, AILERON and ELEVATOR.
Set your sticks to center position. You can also enter you monitor function (if you have this on your transmitter).
Sticks in center position.
When confirming center stick position in the monitor function, make sure PITCH is at 0%
Leave sticks centered during the entire 90° process.
Plug your servos into the ELE, AIL and PIT ports of the 3GX unit. At this point it does not matter what servo goes where.
Look at what general direction the servo arms are pointing, this is what we're trying for.
Get out your servo arms.
Again, remember to take out any sub trim you might have had.
Now swap the servo arms/horns around until you get one that sits as close to 90° as possible. You can also swap servos around, there is no defined function for each servo yet.
Trying servo arms. This is close but I can do better.
This one was worse then the previous.
Perfect!
You may not be able to get it perfectly 90°, but you should swap around until you get as close as possible.
Mine turned out like this.
After this point the servos function is defined, which mean you should not loose track of what's what. If you lined up yours as I did, your order is like this; ELEVATOR far left, PITCH in the middle, AILERON to the right.
Disconnect the servos. Again, remember what's what.
Connect the servos back in, this time to their designated ports. AILERON servo into AIL port etc.
In this step we will use sub trim to get a perfect 90°.
Find your sub trim menu.
Line up all the servos. Use a ruler or something to make them sit parallel besides each other. Then use a ruler as a guide. The ruler must line up with the center holes in the servo arms.
Now the goal is to achieve all arms in parallel with the ruler - use sub trim to achieve this. When doing this you should also be aware that we do want to use as little sub trim as possible. Up to 15 steps is perfectly fine, up to 30 steps is OK, up to 50 steps is a lot, over 50 steps I would not recommend. If you are unable to achieve 90° with under 50 steps of sub trim - you should consider getting new servo arms/horns.
When you have acheived 90° on all three servos, you are done with the 90'ing of servos. You should NEVER mess with sub trim on ELEVATOR, AILERON or PITCH again - if you do, you will have to redo this entire procedure.
SUB TRIM IS LEFT AT THESE SETTINGS!
You are now done and ready to run the wiring. Before you start wiring, remember to label the servos so you remember what servo goes where.
Labeled servos.
Servos set in their designated spots.
Leveling the swash.
A level swash is key to get a stable hover and predictable flight behavior.
Put the 3GX in DIR mode again.
Center sticks (let them remain in this position during the entire leveling process).
Remove the head.
Some people use the so-called "zip tie trick" to level the swash. This method is not as accurate as with a swash level tool.
One does NOT use sub trim to achieve a level swash!
Swash level tool.
Place the tool on top of the swash.
Align the tools arms with the swash arms.
The goal is to make the swash level with the tool. Each of the three arms can be lowered or raised to achieve this.
In this case, the swash arm should be raised. Meaning that the link below should be lengthened.
BUT, one should look at all three links before adjusting. If one is higher than both the other two, this one should of course be lowered - and not the other two be raised.
Adjust length of links until you get all three points level with the tool.
Perfectly adjusted (Pitch to the left, elevator to the right).
Perfectly adjusted (Elevator to the left, aileron to the right).
The swash is now level.
If you are to adjust link lengths in the future, you will raise ALL links the same amount. E.G: you raise ELEVATOR by two turns - you also raise AILERON and PITCH two turns.
Finding 0° pitch at mid stick
Put the head back on (snap on the links as well - forgot to do this in picture).
We will now adjust the blade grip links - these are the two links which connect the swash to the main blades.
The transmitter should still be at mid sticks. The goal is to get 0° on both blades.
3GX still in DIR mode.
Get out your pitch gauge.
Position the blades parallel with the bird. One blade pointing forwards - one backwards.
Parallel with helicopter.
One blade at a time!
Measure the pitch. If you get 0° no adjustment is needed.
If you get positive (e.g. +3°) you shorten the link for that particular blade one turn at a time until you get 0°.
If you get negative (e.g. -3°) you lengthen the link.
When you have achieved 0° on one blade, you turn the rotor head 180° to get the other blade in the same position as the first. Then do the same procedure for blade no. 2.
Lengthen or shorten blade grip link depending on what pitch value you got.
You should now have 0° pitch on both blades (00.4° was the closest I got).
Finding the middle of collective range.
Blades still parallel to helicopter.
3GX still in DIR mode.
Find your "swashplate" menu.
Find the PIT value. This value adjusts the collective range of your bird (more on that later on).
Raise the left stick to highest position.
Check your pitch.
Lower the stick to lowest position.
Check your pitch.
NOW:
I got +9.3° at high pitch.
I got -11.3° at low pitch.
This indicates that my center stick position (0°) is not in the middle of it's range. The goal is to have even number above and below 0° (mid stick) - the reason being that you want an opposite but equal amount of pitch on both negative and positive during flight.
To get the best control of a bird, so-called "collective management", you want this.
SO:
If you get more negative than positive like I did (+9° / -11°), you raise the entire swash. REMEMBER, raise all swash links the same amount - and one full turn at a time. Don't mess this up
If you get more positive than negative (e.g. +11° / -9°), you lower the entire swash. REMEMBER, lower all swash links the same amount - and one full turn at a time. Don't mess this up
When the swash is raised or lowered one turn, you will have to redo the 0° at mid stick again (see "Finding 0° pitch at mid stick" further up, if you forgot).
This part is tricky, and most lightly you will not get a perfect balance between positive and negative pitch. Usually you get 1-2° off - but you should adjust until you get it as close as possible. This process takes time and focus - don't rush!
Raise or lower depending on your pitch reading.
I ended up with this, 10° at high stick.
I ended up with this, 0.04° at mid stick.
I ended up with this, -10.6 at low stick.
Adjusting collective range
Now that you found your optimal center between negative and positive pitch, you can adjust your collective range.
The range will increase/decrease relatively proportional on both negative and positive pitch when adjusting collective range. E.g. at a range value of +40 on the transmitter you might get +10° on high stick and -10° on low stick - but if you increase the value to +60 you might get +15° at high stick and -15° on low stick.
There are three things to consider when adjusting collective range:
- Pilot skill level
- Servo binding
- Power efficiency
A beginner pilot might want a low collective range e.g. +9°/-9° - this will prevent rapid climb rate and present a more docile helicopter. A seasoned pilot might want a high collective range e.g. +13°/-13° - this will give a fast and agile helicopter.
If one was to use too high a collective, one might cause binding in servos as they try to achieve a throw that is out of their range. Consult the helicopter build manual to find details on this.
The less collective range that is utilized, the more power efficient a bird you will get. It's better to increase head speed than to increase collective range.
So, decide what range you want. Set your left stick to highest position.
Look at your pitch value.
While looking at the pitch value, increase or decrease the PIT value.
Raising the value will give more positive pitch.
You can also check your negative pitch - just set your left stick at lowest position.
I'm going for +10° at high stick.
I achieved +10° at a value of +41 on my transmitter.
_____________
You should now have a perfectly set up head, the next step now will be to do the rest of the 3GX setup.
If you have questions concerning the topics in this post, feel free to comment. If you have questions related to other issues, please post in the forum.
Good luck!
