TriCopter & Futaba 9c setup and configuration - RC Groups
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Jul 16, 2010, 06:38 AM
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TriCopter & Futaba 9c setup and configuration

Quick settings if you understand and don't want to read on:
Swash AFR : Ail +30, Ele -30, PIT +100 ( or may need to change the + - sign to reverese according to your setup )
Pitch Curve mix : 0 40 55 70 85
Throttle curve mix: 10 10 1010 10 (or 90 90 90 90 90 if needs to be reversed for Gyro Rate mode)
Gyro: 20 20 (or 80 80 if needs to be reversed )

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Understanding the TriCopter TX settings in a Futaba 9c - particulalry for non Heli Pilots!!

I wrote this as I am not a heli pilot and needed to understand and figure it out for myself! Writing it down helped. And maybe it will help some others. And your probably starting out too which is whay you are reading this.
It's not difficult, but can take some time to understand and for it to "click in to place". It will eventually.

The Tri uses a 120 degree swash plate setup to control the motors and hence pan / tilt and climb/descent. The yaw/rudder control is more traditional, but is contolled by tilting one of the motors. Simple and clever. You don't need to know how swash plates work, but it does help. Explanantions are out there on the web - although if you build a Tri, you will probably figure it out yourself once you understand the settings.

Programming the TX - Starting point
A Heli model on the tx with default Futaba settings.
Select model type of Heli - SR-3

Swash AFR settings
This is the amount of control and direction given to the ESC's to provide Pitch and Tilt control by varying the amount of ESC throttle to the motors via CH1, Ch2 and CH6. Shouldn't have to touch these unless fine tuning. Use normal trims to start with if your tri is tilting going too much in one direction.
Note the the Ail and Ele swash settings equate to rates on a plane. i.e. if it's a bit sensitive try reducing.
Keep Pit at 100% - this is the amount of throttle available. Can't see a reason to lower this

First starting point is: Ail +30, Ele-30, PIT +100 ( or may need to change the + - sign to reverese according to your setup )

Pitch Curve mix (for Non Heli guys, this is your throttle on a tri!!)
To keep it simple in this 120 swash Heli setup, the throttle stick that normally controls the CH3 throttle instead controls the 3 servos that control the pitch of a heli blade - or in the Tri Case - the throttle or power to the motors.
As you move your throttle stick up, the 120 heli mixing drives the three channels CH1, CH2 and CH6 at the same time effectively applying the same throttle increase to each one.
You can leave throttle high point at 85% to allow the gyro to provide extra power if it needs to stabilise, although some put higher - even 100% if the Tri is carrying a full payload.
The settings are distributed more evenly through the centrepoint rather than a linear 0-100% - This gives a much more controllability of the power accross a longer stick movement.

First starting point for TX settings is: 0 40 55 70 85

Throttle curve mix
First thing to understand on theTri is that the traditional throttle channel (CH3) is not used to control the Tri throttle, direction or ESC. Think of it as an unused spare channel.
When you throttle up, although you are moving the throttle contol, the mix into the 3 channels driving the ESC's are what increases the rpm and not ch3

About the gyro...
The HK401b and similar gyros can work in Gyro Rate (GR) or Heading Hold (HH) mode. In GR mode, when it detects a force on it, it will try to compensate with and equal amount in the opposite direction to stabilise. In HH mode it will try to maintain same heading as the name suggests.
Putting a 401b into GR or HH mode is done via a control channel from your RX. Imagine center stick is off, full one direction is 100% GR and full other direction is 100% HH. And proportionally in between.

OK so now putting the two items together.
Connect the three ESC's to the throttle channel so the Gyro operational mode and amount of control the gyro has can be applied.
The throttle curve is now set so that all points have the same value.
What this means is that as far as the throttle channel (ch3 )is concerend, whatever the stick position it, CH3 will always give the same output value that you sett the throttle points to be.
Now it might start to make sense - you can use it to tell teh gyro if it is in GR or HH mode - and how strong the gyro effect will be.

e.g., for the figure that you program the throttle curve with:-
0%= GR mode running at 100% rate
25% - GR mode running at 50% rate
50% - No GR or HH
75% - HH mode running at 50% rate
100% - HH mode running at 100% rate

On some RX units, the HH/GR might be opposite way around.

First starting point for TX settings is: 10 10 1010 10 (or 90 90 90 90 90 if needs to be reversed for GR mode)

This is used to control the yaw gyro gain of the Gyro connected to the Yaw servo.
Typically this value is set to tell the gyro to work in Heading hold mode and how much control authoristy it has.
This is whjat will hopefully keep your Tri pointing in teh same direction

First starting point for TX settings is: 20 20 (or 80 80 if needs to be reversed )

Revo mix
This should be inhibited on a Tri using heading hold gyro

Now read it all again - several times until you get it !! And do it whilst setting up your try - it will click sooner or later.

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Setting up the HK401b Gyros
Turn the delay control to min (full anti-clockwise)
Turn the rate control to mid-point. For some radios this might be better at max (full clockwise)
The three motor ESC's should be set in Gyro Rate mode
The Yaw pivot Gyro should be in Heading Hold mode (although see setting up YAW gyro below)
The LED on the gyros should blink on power up then go out. If they stay on then they are in heading hold mode
Start with Gyros set to standard mode servos - can try digital at a later stage to see if it improves performance.
For slower servos, can try turning up the yaw pivot gyro to stop tail wag. Better to have faster servos. Shouldn't be needed

The Yaw pivot Gyro should have the face pointing upwards (the face is the side with switches and pots)
The three ESC gyros should be facing sideways and in the same direction - can use switches to reverse direction if needed

************************************************** ****************
Setting up the yaw trim (for the recommended heading hold mode)
Set the gyro in disabled mode temporarily.
Set transmitter yaw trim to center.
Power up the model.
Now trim the model for no drift using mechanical adjustments.
Power down the model.
Put the gyro in heading hold as per settings above.
Power up the model and it should have minimal drift.
Note that if you use a variable or switched channel for yaw gyro, it must always be powered up in HH mode.
Using a three prosition switch is perfect. one direction set HH, one disabled and one for GR mode

************************************************** ****************
Calibrating the ESC's (for HK SS models)

For some ESC, may have to set TX to full throttle before powering up the ESC to make sure they all have their endpoints set the same (CAUTION - hold down Tri when doing this!). On some this only needs to be done once.
Set throttle, aileron and elevator trims to center
Put throttle to full
Power up the Tri rx/gyros etc.
Power up the ESC.
As soon as the ESC's beep, turn the throttle down to zero

************************************************** ****************
Advanced Settings / fine tuning once you can fly:

Throttle curve mix
Remember from above - your First starting point for TX settings is: 10 10 10 10 10 (or 90 90 90 90 90 if needs to be reversed for GR mode)
and that this channel is used purely to set the amount of Gyro rates for the motors / ESC.

Now at low throttle positions, you generally could do with a slightly higher rate compensation than at high throttle settings - a higher % change in throttle is needed to maintain equilibrium.
So on the assumption that your midpoint is set spot on, try something like: 06 08 10 12 14 (or 94 92 90 88 86 if reversed needed)
Until you can fly well and want to tweak for maximimum, recommend concentrating on getting the Tri stable with the previous settings.

The impact of this is most noticeable when dropping from a hight on low power - the tri can become quite erratic and cyclic from side to side. Remember low throttle settings need more gyro compensation - what is happening on the low power descent is the gyro's cannont provide enough change to compensate quick enough - so turning it up at low throttle can help. But also remeber, turning it may mean putting it closer to 0 !! If 0 is max rates.

Pitch curve mix
Remember from above that this is used to control the speed of the props and the intention here is:
- enable hover point of tri to be approximately the center point of the throttle stick.
- enable widest possible stick movement to control the ascent / descent of the tri (at least half of the stick movement). Makes the Tri easier to control
- enable the gyros to have enough additional power for corrections - even if the pilot is applying full throttle available to him

This is how to set it up.... (this is for the more common 5 point curve):
- first point - increase the value until props start spinning, then back it off slightly so they stop.
- third - set the value to that which it takes to hover the Tri
- last point - set to a value which gives you good climb rate, but leaves plenty of headroom for gyros to increase thrust further when needed. Expect this to be in range 60-85%. Start with 70%
- 2nd and 4th points should now be about 10% under and over the third point.

************************************************** ****************
Other tips:
Make sure the Tri balanced as close as possible to the centre point every flight.
Mount the Gyros on acrylic foam tape (gel tape)
Hot glue the HK401b's internals so they do not shake around.
When setting up the YAW, adjust it mechanically for a stable directional hover. Make sure all digital trims are centered. Shouldn't need to adjust trims if Yaw trim and COG is set right. The Yaw Gyro seems to work much better with trim centered. If trim settings are changed in heading hold, the unit should be power cycled.
For some motors, constant flexing of the yaw pivot breaks the wire. Cable tie it so the flexing is on a flexible part!!
For those that use Towerpro type bell motors retained by grub srews, use a dab of cyano or threadlock on them to stop vibrating loose.
For those that use Towerpro type bell motors, cut excess spindle off - reduces likelyhood of bending in a crash.
For those that use Towerpro type bell motors, make sure that if needed a blind hole is partly drilleed into into the mounting to ensure the motor shaft does not bind on the mounting. This will kill a motor quickly and cause a tri to keep dropping an arm.
If using a BEC (required for SS controllers), ensure the power lead from all three ESC's are disconnected (cut - or centre pin pulled and insulated.
Put a dab of very light oil on the bearings every few flights using a precision oiler

Startup routine:
Power up TX with all switches etc. in coprrect position
Power up the BEC/RX/Gyros.
Once Armed, Power up the ESC

Info to be verified...
Full left and then full right on the rudder a couple of time before take off. Resets heading hold.... (to be verified)

************************************************** ****************
Alternative Components

Turnigy 2217-20
RC Timer BC2836-11 (4mm shaft, impossible to bend and comes with a collet prop adapter that fits the APC props. The GWS would require a different mount)
Last edited by Shikra; Nov 01, 2010 at 06:41 AM.
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Aug 02, 2010, 07:01 PM
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SSM's Avatar
Great guide to setting up a Tri - thanks Shikra. Simon
Aug 03, 2010, 09:28 AM
I think my wheels fell off.
Thumb_number's Avatar
Thank you Shikra. This is very valuable information.

Jan 10, 2011, 11:08 PM
dalbert02's Avatar
This is awesome! You should have put it under the tricopter forum too. I've been searching for this info for a long time through rcgroups but just found it today by way of google. Thanks!
Jan 30, 2011, 12:20 AM
Registered User
Wow!! Thank you!! I have exactly the same components but was not able to make my tri stable. Your info are awesome!! Thanks.. you probably save me a lot of crash and ripped servo too
Feb 12, 2011, 12:27 PM
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Darth_Elevator's Avatar
This thread is extremely helpful. Thank you, thank you, thank you!
Mar 17, 2011, 12:29 AM
Registered User
Thanks for taking the time to do this. I am new and this is a big help.
Sep 23, 2011, 01:20 PM
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Darth_Elevator's Avatar
Futaba 9C with Dragonlink module: motors won't arm

It's probably a longshot that anyone will know the answer to this question, but I'll post it anyway, just in case....

I've been successfully flying my tricopter thanks to the excellent information in this thread on how to program my Futaba 9C. I've been flying with a Spektrum module and rx. I decided to try my dragonlink module and rx (not for long range flying but because it has one more channel than my Spektrum rx, which channel I intend to use for the remote trigger on my camera).

So I don't change any settings on the radio and just switch all the servo plugs out of the Spektrum rx and into the dragonlink rx. The servo plugs are labeled, btw, so I triple checked to make sure everything is seemingly plugged in the same.

However, I can't get the motors to arm. I switched everything back to the Spektrum rx and motors arm just fine and it flies normally. All switches are the same, all programming is the same, and I thought I had the channel assignment correct for Dragonlink with Futaba, but I'm obviously missing something. (All of this testing, BTW, is without the remote trigger plugged in to the extra channel.)

Any ideas?

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