SU-35 Simple Gyro-Stabilization! - Page 11 - RC Groups
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Nov 12, 2008, 08:06 AM
Ted M
Gandalf_Sr's Avatar
If you go back to my post #108, you'll see the sketch I posted for how I think the setup will work Note this is a revised version posted today Nov 12,2008, the only difference is that the mixer for the rear control surfaces gets an input from the pitch gyro output - before this was wrongly fed through the front canard mixer.

You will notice that my design uses mixers to mix the gyro output with a channel I'm calling Hi Alpha (HiA). Mixers are used so that the following effects are produced:
- Normal Canards are level and controlled by the pitch (elevator) gyro
- Hi Alpha Canards are controlled by the pitch gyro but are offset up at the rear edge - amount of offset is controlled by the HiAlpha channel

Aileron Surfaces
- Normal Ailerons are level and controlled by the roll (aileron) gyro
- Hi Alpha Ailerons are controlled by the roll gyro but are offset up at the rear edge - amount of offset is controlled by the HiAlpha channel

Rear Surfaces + Motors
For normal and HiAlpha, the rear surfaces and motors are controlled by a mixture of pitch and roll gyros

Note As far as I can tell, RCSuperPowers' pitch gyro only controls the canard. He does produce an offset on the canards and elevons when he switches into HiA mode. In my design, the HiA channel produces an offset to the center position of 3 gyro-controlled servos (1 for canard and 2 for ailerons), I plan to initially control the HiA channel with a proportional control on my transmitter; from the video it looks like RCSuperPowers controls his with a switch.

A mixer is pretty easy to understand, it's basically got 2 inputs and 2 outputs. One input makes the servos move in opposite directions and the other input makes them move in the same direction. I'm using Digimix II mixers that have cool programmable features such as reversing; you can find them on eBay.

One caveat on all this... I HAVE NOT YET BUILT THE SYSTEM I POSTED THE DESIGN FOR. I've been busy with work and honey-do stuff. Also, now that I've printed out the plan, I've realized that I need to make something (wings?) removeable if I am going to be able to transport the plane in a vehicle because the WS is 47.5 inches.
Last edited by Gandalf_Sr; Nov 12, 2008 at 09:17 AM.
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Nov 12, 2008, 10:45 AM
Registered User
Go4it's Avatar

SU-35 three axis gyro setup

The attached wiring diagraw is Dave's Superpowers but I thought I understood it, until I tried setting it up. And now, I don't have a clue how it works completly. I did email Dave and he said he would get back on this project next year.
Nov 12, 2008, 03:00 PM
Ted M
Gandalf_Sr's Avatar
Originally Posted by Go4it
The attached wiring diagraw is Dave's Superpowers but I thought I understood it, until I tried setting it up. And now, I don't have a clue how it works completly. I did email Dave and he said he would get back on this project next year.
Actually that is MY diagram; note that I updated it to correct an error and you are showing the older version; I've added the corrected version as an attachment to this post. What do you want to know?
Last edited by Gandalf_Sr; Nov 13, 2008 at 07:01 AM.
Nov 12, 2008, 03:27 PM
Registered User
Go4it's Avatar

SU-35 three axis gyro setup


All this time I thought this was Dave's diagram, sorry.
I guess what I need is a updated wiring diagram for the 3 axis sytem to do Hi alpha flight on a Su-35 with conards that tie into the gyro's and how the other gyro's are wired

Dave shows
2- BEC's
2- 40amp ESC
2-2200 lipo's
2-6 Ch receivers
Last edited by Go4it; Nov 13, 2008 at 11:06 AM.
Nov 15, 2008, 03:34 PM
Ted M
Gandalf_Sr's Avatar

Basic Tests Work OK

I wired up 2 of my Digimix II mixers, one was behaving weird but was fine after I ran the programming routine on it. Then I added an EK2-0704 gyro to simulate the pitch gyro with the gyro output driving 1 of the mixer inputs and the other was connected to the HiAlpha channel of my receiver. I got exactly what I wanted so, as I expected, that confirms that the Digimix IIs are happy working with the output from the EK2-0704 gyros.

Trying to figure out what I need to do to make the wings removable or something.
Nov 15, 2008, 06:52 PM
Fill'er Up!
mattyhawk's Avatar
Nov 15, 2008, 09:51 PM
Registered User
Go4it's Avatar


Great, that will help save some money. Keep up the great work.Digimax ll are half the price and the gyro at $12 can't beat it.
Dec 01, 2008, 07:33 AM
Ted M
Gandalf_Sr's Avatar
I've been agonizing over the size of this moster; nearly 48 inch wingspan. I considered making a smaller version that used 6 inch props but my motors are known good with 7x5 props and anyway, my plan is only about 17% bigger than RCSuperPowers' (based off some measurements from the pictures and assuming he is 'normal' height); given that he comments that he wanted to try and build lighter, I guess that the extra wing area will work in my favor.

I plan to make it from inch Fan Fold Foam (FFF). I will make the rear fuse main deck out of double FFF with removable Kline Fogelman (KF) wings; there will be 2 CF rods that allow the wings to slide on from the sides.

Basic calcs show that I can get 530 W out of my motors but I still need to keep the build light - around 1400g (3 lbs) - in order to get hovering power to weight ratios.
Dec 03, 2008, 07:04 AM
Ted M
Gandalf_Sr's Avatar
I was asked a question by Scottcr and thought I'd repeat it here for everyone to benefit from...

Originally Posted by Scottcr
Gandalf: I was wondering if you could help me with some gyro help? When Dave is holding his plane and he shows it pitching up the canards pitch down and as long as he is pitching the nose of the plane up the gyro maintains the canards in a pitch down config. I have the same gyro yet when I pitch up the gyro does pitch the canards down but does not hold it. Holding the plane with nose pitched up the gyro moves the canards back to neutral. How do I get the gyro to hold the pitch down as long as I hold the nose pitch up??? If you could help me out I would greatly appreciate it. I have a DX 6 trans the same as Dave. I am assuming it must be a programming solution but it is driving me nuts.

No probs Scott. The gyros that Dave (RCSuperPowers) is using are rate gyros (eSky 0704) and they detect movement in their control axis. So your description of what's happening matches my expectations. Try this explanation:

When you have the elevator control in the center position; this is feeding the gyro with a signal that really says "try to maintain a zero movement rate in the pitch axis". As the plane nose moves upward, the pitch gyro detects the movement and reacts by moving the canard to produce a downwards force on the nose - it's a rate gyro so the faster you move the nose up, the more the servo deflects down but only while the nose is moving. If you stop moving the plane, the gyro will center the canard again because it thinks it has stopped the movement. I think you may be confused by Dave's video - If you watch it carefully, you'll see that Dave throws a switch that causes the offset down pitch of the canards (and up pitch on the ailerons). In my diagram, you'll see that I implement that effect using a channel I call Hi Alpha although it's just a spare channel on the radio - I plan to control it using a linear control on my 12FGH transmitter.
Dec 03, 2008, 08:51 AM
Registered User
Thanks Gandalf for the explanation. So let me see if I have this correct. I understand now that if the nose of the plane stops moving the gyro will go back to neutral. After looking at the video closely I did see them go back to neutral when Dave held the plane still. When he does the hialpha he has the gyro set up so the canards are pitched down which means even if the planes nose was pitched down the canards would still be in a pitched down config until he flipped the switch again.

I have not built the SU35 yet but put canards on my Northstar foamy.

Dec 03, 2008, 09:19 AM
Ted M
Gandalf_Sr's Avatar
Scott, it seems like you have fully understood

One word of warning, canards can make a plane VERY sensitive in the pitch axis, I suggest the following approach:

1. Make the plane fly OK with the canards level (maybe with the canard servo disconnected as long as the canards aren't likely to move in flight)
2. Connect with the gyro running the canards and set the gain of the gyro to a low value (50% suggested)
3. Test fly and gradually increase the gyro gain until you're happy with performance

Note. If the pitch is 'wobbling' then the gain may be too high, my experience was that 50% - 80% was the right range on my X42 but your experience my differ.

Dec 03, 2008, 09:34 AM
Registered User
Thanks Ted you have finally explained it in a way that someone with no knowledge of how gyro's work understands. I will try that and let you know what results I get. I am going to try and get out flying again in the new year. Until then guys have a good Christmas and New Years. I am going south to get away from the cold and snow for a while.
Dec 07, 2008, 09:09 PM
Ted M
Gandalf_Sr's Avatar
I started my build today and decided to create my own build thread which is here.
Dec 13, 2008, 02:42 AM
"It's a Quad" :O
thewz's Avatar
I've got Gyro's and mixers....time to experiment....
Dec 26, 2008, 02:34 AM
What can I crash today?
GeekGod's Avatar
Incredible work Dave and others here.

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