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Old Nov 16, 2012, 06:41 PM
Bruno, GOOD DOG
A Rdnek's Avatar
United States, IA, Grinnell
Joined Aug 2007
4,019 Posts
OK, for those of you that actually want a heading hold, as well as rate Gyro, AND an off position, all controlled from your transmitter....... Here it is......
http://www.headsuprc.com/servlet/the...-A3-Pro/Detail
and it is available right here from a premium dealer in the good old USA.
One word of warning, If you don't know what a heading hold gyro does, you might not want it.
I got one of these from China several months ago. The first and second time I used it, I nearly lost the plane. Since then I have only used it in rate mode or the handy OFF setting.
Rn
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Old Nov 16, 2012, 07:04 PM
Life begins at transition
Australia, VIC, Sale
Joined May 2007
3,593 Posts
During a turn, the heading is changing (hopefully), but the vertical gyro (yaw channel) can still have a zero rate.

Because the gyro is also tilted, the yaw channel doesnt' always line up with heading. This is easiest to understand if you think from the pilot's seat. Yaw means the aircraft nose moving left/right, not north/south. In a steady, coordinated turn, the attitude is stable. That's all the gyro can detect.

Vertical gyros are used in full size aircraft for yaw damping (helps hugely in assymetric too!), and you don't notice any weird reaction; the skidball just stays nailed in the middle.
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Old Nov 16, 2012, 07:52 PM
2^p - 1
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United States, MO, Springfield
Joined Feb 2003
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Baf - short answer, by holding the sticks.
A bit longer answer - if you were to hold the rudder stick to either side, then move the plane in the yaw axis, you would see the gyro trying to make corrections, but it won't overcome the input that's already there.
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Old Nov 16, 2012, 11:25 PM
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Uk South Wales
Joined Aug 2009
2,306 Posts
+1 on the above, the unit only sees movement around an axis not relative to the horizon or any other fixed point. Once you have put the aircraft into a bank by rolling for instance the gyro will try to keep the plane at that attitude. Now depending on the gain setting and the type of plane the results will be quite different. For instance lets take a semi scale cub like plane with some dihedral, put that in a bank and its natural aerodynamic tendancy is to level the wings again. The gyro will try to stop it and at normal gain settings the plane will win and it will stabalise back to wings level, but a bit slower. The effect you will notice is damping of the controls. This is good and is what the unit is good at doing, making a planes flight smoother, ideal for onboard video. Turn the gains up too high however and it will fight both your input to put the plane in the bank and also the planes built in stability, the result being a strange sort of jerky flight pattern. Now lets put it in a neutraly stable 3d model that is trimmed to fly perfectly. Put this plane in a bank and as long as you have enough power applied it will continue until you tell it otherwise. Take this to the extreme and roll to knife edge and the gyro (once set up, and that can be a bit time consuming) will keep it there. Once all 3 axis are adjusted it will even keep a 3d model in a stable hands off hover.

Now one thing that some of the larger foamies suffer from is poor coordination in the turn, you often see them in turns dragging the tail low, the gyro can help this as it will try to keep the tail up if it starts to drop (or keep the nose up if it starts to drop)

The trick is finding the 'sweet spot' for the gain pots for the particular plane you have, this will be different for every plane but experimenting will get you to a good starting point. Start low and add more gain until you are happy. Dont start with the gains at the highest and work backwards as the unit will suffer from extreme feedback and the plane will overcorrect then correct itself in a viscious feedback loop that may result in loss of control or in the extreme dissintergration of the model. I had one model that damm near wagged its tail off it oscillated so quickly.......

The perfect outcome is to make your plane smoother to fly, almost like flying a heavier plane with more inertia. I used mine on my Dynam Catalina and it was nice when set up.

There is of course a BUT......I find that with the gains high enough to make a real difference you gett a slightly dissconnected feel to your flight, so I tend to use just one or two axis to get rid of a particular trait, on the Catalina it was pitch that needed smoothing.

Your results will be unique to you as you set up the plane as you like it.

Dave
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Old Nov 17, 2012, 10:49 AM
The sky is the limit
BAF23's Avatar
Belgium, Vlaams Gewest, Hasselt
Joined Aug 2012
193 Posts
Quote:
Originally Posted by Odysis View Post
During a turn, the heading is changing (hopefully), but the vertical gyro (yaw channel) can still have a zero rate.

Because the gyro is also tilted, the yaw channel doesnt' always line up with heading. This is easiest to understand if you think from the pilot's seat. Yaw means the aircraft nose moving left/right, not north/south. In a steady, coordinated turn, the attitude is stable. That's all the gyro can detect.

Vertical gyros are used in full size aircraft for yaw damping (helps hugely in assymetric too!), and you don't notice any weird reaction; the skidball just stays nailed in the middle.
If during a coordinated turn (with heading change) the yaw channel can have a zero rate, how do you explain the needle above the skidball (in a real aircraft) showing a deflection, being nothing but a pure yaw gyro?

Signflyer, does your answer mean that I have to make every turn by putting in a certain bank angle and keep giving rudder input into the turn for the whole duration till I want to rollout? With your answer, even an aileron rudder mix (I usually put in 10% when I cannot program differential ailerons) seems short of getting a continuous steady turn done.

Dave, what I liked about your explanation is that at some point "the plane will win" and allow the bank to change the yaw anyway (or a stable aircraft to revert to wings level after a while despite the roll gyro). It all starts making more sense now, especially after you gave the correlation with the specific aircraft stability and the adjustment of the gains. I'm flying scale with mild aerobatics and have no aspirations in 3D flying.

Thanks for the info guys, anxious to try it all out next spring.
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Old Nov 17, 2012, 11:57 AM
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Uk South Wales
Joined Aug 2009
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Baf I think these units get too much thinking done about them.

The simplest things to say are:

Every plane will react different when you put one of these in it and trial and error will be needed to dial it in.

And of course every pilot is different and so some will love the results and some will hate them...........I am in the loving on my 3d (makes me look good....lol) but I am in the hating on most of my planes as it just doesn't feel right. It may just be that after 30 years I am set in my ways......lol

Best of luck when you get the weather and stick with it as they can take some time to get 'just so'

Dave
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Old Nov 18, 2012, 02:40 AM
Life begins at transition
Australia, VIC, Sale
Joined May 2007
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Quote:
Originally Posted by BAF23 View Post
If during a coordinated turn (with heading change) the yaw channel can have a zero rate, how do you explain the needle above the skidball (in a real aircraft) showing a deflection, being nothing but a pure yaw gyro?
True, it was a large oversimplification.
Given it's been a while since I've even seen a turn/balance, I had to look up again how they work!

Anyway, the systems I've worked with are much more complex than this box (where I assume all 3 axis are independant).
A good description of a proper yaw damper is in here

I assume this gyro uses a highpass filter to stop fast movements to the aircraft, but allow slow ones to continue. That would mean although in a turn the pilot hasn't commanded a heading change (yaw channel wise), the gyro won't fight it too hard.
If a rapid change happens (wind gust) kicks it, it'll fight back to smooth it out.

Has anyone checked the fuses to see if the firmware can be downloaded?
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Old Nov 18, 2012, 10:30 AM
The sky is the limit
BAF23's Avatar
Belgium, Vlaams Gewest, Hasselt
Joined Aug 2012
193 Posts
Quote:
Originally Posted by Odysis View Post
I assume this gyro uses a highpass filter to stop fast movements to the aircraft, but allow slow ones to continue. That would mean although in a turn the pilot hasn't commanded a heading change (yaw channel wise), the gyro won't fight it too hard.
If a rapid change happens (wind gust) kicks it, it'll fight back to smooth it out.
That answers all my questions and reassures me on the use of the system.

The four pages of technical stuff in the link you provided catapulted me back a few decades ago, the F104 Starfighter and Swearingen Merlin III were by design aircraft that heavily relied upon SAS systems and flying without was a very unpleasant experience that quickly could get out of hand and even cause loss of control.
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Old Nov 18, 2012, 01:54 PM
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cneff's Avatar
Germany, HE, Seeheim-Jugenheim
Joined Nov 2012
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Quote:
Originally Posted by dav3uk View Post
+1 on the above, the unit only sees movement around an axis not relative to the horizon or any other fixed point. Once you have put the aircraft into a bank by rolling for instance the gyro will try to keep the plane at that attitude. Now depending on the gain setting and the type of plane the results will be quite different. For instance lets take a semi scale cub like plane with some dihedral, put that in a bank and its natural aerodynamic tendancy is to level the wings again. The gyro will try to stop it and at normal gain settings the plane will win and it will stabalise back to wings level, but a bit slower. The effect you will notice is damping of the controls. This is good and is what the unit is good at doing, making a planes flight smoother, ideal for onboard video. Turn the gains up too high however and it will fight both your input to put the plane in the bank and also the planes built in stability, the result being a strange sort of jerky flight pattern. Now lets put it in a neutraly stable 3d model that is trimmed to fly perfectly. Put this plane in a bank and as long as you have enough power applied it will continue until you tell it otherwise. Take this to the extreme and roll to knife edge and the gyro (once set up, and that can be a bit time consuming) will keep it there. Once all 3 axis are adjusted it will even keep a 3d model in a stable hands off hover.

Now one thing that some of the larger foamies suffer from is poor coordination in the turn, you often see them in turns dragging the tail low, the gyro can help this as it will try to keep the tail up if it starts to drop (or keep the nose up if it starts to drop)

The trick is finding the 'sweet spot' for the gain pots for the particular plane you have, this will be different for every plane but experimenting will get you to a good starting point. Start low and add more gain until you are happy. Dont start with the gains at the highest and work backwards as the unit will suffer from extreme feedback and the plane will overcorrect then correct itself in a viscious feedback loop that may result in loss of control or in the extreme dissintergration of the model. I had one model that damm near wagged its tail off it oscillated so quickly.......

The perfect outcome is to make your plane smoother to fly, almost like flying a heavier plane with more inertia. I used mine on my Dynam Catalina and it was nice when set up.

There is of course a BUT......I find that with the gains high enough to make a real difference you gett a slightly dissconnected feel to your flight, so I tend to use just one or two axis to get rid of a particular trait, on the Catalina it was pitch that needed smoothing.

Your results will be unique to you as you set up the plane as you like it.

Dave
Totally agree and very good explaination of this little wonder of technic.
Mounted it into my Parkzone BF109 and it's absolut more fun to fly than before.
Greetings from Darmstadt Germany
Peter
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Old Nov 19, 2012, 10:11 AM
The sky is the limit
BAF23's Avatar
Belgium, Vlaams Gewest, Hasselt
Joined Aug 2012
193 Posts
Just one more question. Having spend so many hours detailing the T6, DC3 and Stearman I have no desire to experiment on those aircraft (delicate landing gears). I initially thought testing those gyro's out on my funcub, but not wanting to each time take the wing off, and the limited accessibility of the receiver compartment led me to consider the use of a straight out of the box assembled FMS 150mm P51Mustang taildragger to get used to the gyro's. That airframe is rather forgiving and offers excellent accessibility through the huge cockpit to install or remove the gyro system or make adjustments to the gains even on the runway.

Does anybody has experience with testing out and fine tuning the gyro's on one airframe, then installing them on a different airframe hopefully only requiring minimal gain changes (but with already a solid response). What I had in mind was getting all three gyro systems first installed one by one and adjusted in my (relatively expendable and not so critical) P51, then move each of them into the 3 more critical models. The fact the P51 flies on 4S and the other three on 3S shouldn't affect the gyro's because they are powered by the reduced voltage from the Spectrum receivers. Anything wrong with those ideas?
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Old Nov 19, 2012, 11:20 AM
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Uk South Wales
Joined Aug 2009
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Quote:
Originally Posted by BAF23 View Post
Just one more question. Having spend so many hours detailing the T6, DC3 and Stearman I have no desire to experiment on those aircraft (delicate landing gears). I initially thought testing those gyro's out on my funcub, but not wanting to each time take the wing off, and the limited accessibility of the receiver compartment led me to consider the use of a straight out of the box assembled FMS 150mm P51Mustang taildragger to get used to the gyro's. That airframe is rather forgiving and offers excellent accessibility through the huge cockpit to install or remove the gyro system or make adjustments to the gains even on the runway.

Does anybody has experience with testing out and fine tuning the gyro's on one airframe, then installing them on a different airframe hopefully only requiring minimal gain changes (but with already a solid response). What I had in mind was getting all three gyro systems first installed one by one and adjusted in my (relatively expendable and not so critical) P51, then move each of them into the 3 more critical models. The fact the P51 flies on 4S and the other three on 3S shouldn't affect the gyro's because they are powered by the reduced voltage from the Spectrum receivers. Anything wrong with those ideas?
Each plane will be totally different from the next regarding gain settings so you may be lucky and get a close match but it usually takes a few flights of tinkering with the gains to get them as you will want them.

Each plane will have its own built in stability, and response to controls. The P51 will be less stable and more responsive than the cub and the dc3 should be the least responsive so all will need custom settings.

The good thing about them is they are small so can be shoe horned in here and there where there is access, remember it doesn't matter where they go in or outside the plane. You could for instance velcro one to the top of the wing in the cub, fly then adjust, fly adjust and when happy fix it all inside in its permanent location.

Dave
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Old Nov 20, 2012, 02:00 AM
The sky is the limit
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Thank you Dave, your last paragraph effectively replaces all my previous brainstorming and concerns.
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Old Nov 21, 2012, 01:09 PM
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UK, Bedworth
Joined Apr 2004
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Just got back from my second test flight with my stabiliser equipped Easy Star. It's operating on rudder and elevator only.. This time I had turned the gains up on both channels and now have the pots at about 2:30. Conditions were 13mph wind with moderate turbulence, conditions that I would consider flyable without the gyro but not suitable for aerial photography. I'm basing my comments on the aerial video I recorded during the flight.
On the climb out the model seemed more stable in pitch but yaw was still not damped. Transition from power to glide was more difficult to manage smoothly the model tended to stall as the power came off. For the first few transitions I deliberately let the model find its new equilibrium to see how the gyro affected the transition. Without the gyro the model would transition from power to glide smoothly if I reduced power over about 5 seconds. with the gyro this caused a stall , Later I put down elevator in as I reduced power and this helped.
On the glide I set the model into wind and left it hands off as long as possible. It kept it's heading better and seemed more stable in pitch . But if a gust caused a wing to drop then the heading was lost and the nose dropped and I had to intervene to regain the desired flight path.
On approach I needed to apply some firm control inputs and the model seemed to respond less promptly than it did without the gyro. this confirms my observation that the servos run more slowly with the gyro.

So I'm still not sure this thing is working for me. I'm wondering whether to control the rudder via the roll axis on the gyro to try and compensate for the wing dropping. I also have an aileron equipped aerobatic model so may try out all 3 axies on that

Terry
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Old Nov 21, 2012, 02:04 PM
Retired in NC
Rich in ILM's Avatar
USA, NC, Wilmington
Joined Sep 2010
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My experience has been that roll control is the most important of the 3. I can't concieve of implementing without roll damping?
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Old Nov 21, 2012, 02:21 PM
Curiouser and curiouser
Kokopeli's Avatar
Rochester, NY, USA
Joined Oct 2005
2,062 Posts
Quote:
Originally Posted by Rich in ILM View Post
My experience has been that roll control is the most important of the 3. I can't concieve of implementing without roll damping?
Rich, are you talking about only ele/rud as he is or are you talking about ele/rud/ale?
I am most interested in how to best hook it up with just two channels of control.
So Terry, please report on you next trial using roll axis connected to the rudder with no ale. on the plane.
It might help me.

Thanks,

Walt
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