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Old Sep 29, 2008, 07:56 PM
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Joined Sep 2008
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infact by putting a rate gyro on the yaw channel you've created the auto-pilot function of a coordinated turn. I love the idea of rc planes and parkjets, pilots are always the weakest link and by putting them outside the airframe you can achieve manoeuvrers a person would never stay conscious through.
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Old Sep 30, 2008, 05:41 AM
Winging it Ò>
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Joined May 2006
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FMA copilot

I just came across this in the VTOL forum. Looks like another interesting option for flight stabilization.

http://www.fmadirect.com/Detail.htm?...489&section=20
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Old Sep 30, 2008, 07:15 AM
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I think the copilot is geared for keeping the plane level "on the horizon".
My understanding of a gyro is it keeps the plane where you point it, i.e. it resist uncalled for directional changes.
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Old Sep 30, 2008, 08:15 AM
Ted M
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Ann Arbor, MI, USA
Joined Feb 2007
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Quote:
Originally Posted by MiseryQ
I think the copilot is geared for keeping the plane level "on the horizon".
My understanding of a gyro is it keeps the plane where you point it, i.e. it resist uncalled for directional changes.
In center stick you're right, the rate gyro will try to counter any movement of the axis it's controlling. When a non-center stick input is fed to the gyro, it tries to maintain a rate of angular change for the controlled axis e.g. 90º per second and more stick = greater rate of change.

True head-hold (HH) gyros work the same as rate gyros but go one better because they measure the angular movement that ocurred so that when they drive the servo to put the axis back to where it was, they measure the same but opposite amount of angular movement, IF they get it right, your axis remain pointing in one direction. Cheap gyros tend to suffer from drift as temperature changes, more expensive ones don't. If you want a really good, small gyro, then the LogicTech 2100T is hard to beat at around $100.

The gyro that RCSuperpowers is recommending is the EK2-0704 rate gyro. If you order from Hobby City*, they have it for $12.60. I already have an EK2-0704A gyro (I think I paid $38 for it a while back) that looks similar but can be remotely switched between rate and HH mode using a spare channel (or permanently set to rate or HH mode without using up a channel). I have started installation of this gyro into a fast delta wing + canard plane to control the pitch axis; I'll let you know how it goes.

Ted

* Shipping cost from Hong Kong is a major factor if you are just buying 1 gyro and the shipping cost to return if it's defective makes RMA a non-starter (until they get a US address to RMA back to). I have ordered a LOT of stuff from Hobby City and most of it's been good although I got $70 worth of bad servos on a recent order - however, I still think that I'm doing well given how cheap their prices are.
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Old Sep 30, 2008, 08:50 AM
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Canton, Michigan USA
Joined Jul 2007
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Quote:
Originally Posted by Gandalf_Sr
In center stick you're right, the rate gyro will try to counter any movement of the axis it's controlling. When a non-center stick input is fed to the gyro, it tries to maintain a rate of angular change for the controlled axis e.g. 90º per second and more stick = greater rate of change.

True head-hold (HH) gyros work the same as rate gyros but go one better because they measure the angular movement that ocurred so that when they drive the servo to put the axis back to where it was, they measure the same but opposite amount of angular movement, IF they get it right, your axis remain pointing in one direction. Cheap gyros tend to suffer from drift as temperature changes, more expensive ones don't. If you want a really good, small gyro, then the LogicTech 2100T is hard to beat at around $100.

The gyro that RCSuperpowers is recommending is the EK2-0704 rate gyro. If you order from Hobby City*, they have it for $12.60. I already have an EK2-0704A gyro (I think I paid $38 for it a while back) that looks similar but can be remotely switched between rate and HH mode using a spare channel (or permanently set to rate or HH mode without using up a channel). I have started installation of this gyro into a fast delta wing + canard plane to control the pitch axis; I'll let you know how it goes.

Ted

* Shipping cost from Hong Kong is a major factor if you are just buying 1 gyro and the shipping cost to return if it's defective makes RMA a non-starter (until they get a US address to RMA back to). I have ordered a LOT of stuff from Hobby City and most of it's been good although I got $70 worth of bad servos on a recent order - however, I still think that I'm doing well given how cheap their prices are.
I, too, have the EK2 0704A gyros (a pair of them) NIB that were destined for a AP but never used. The price I paid was closer to $30. I would like to use them on my elevon planes. I need a quick "how-to" review to install in an elevon plane. My elevon planes currently uses the radio for elevon mixing which is a no-no for gyros. I do have an old FMA direct mixer I can cannabilize from a flying wing I never got around to flying. My goal would be to use both gyros to experiment with pitch and roll control. How are these wired into the system?

Regarding Hobby City.
I have only been burned on ABF batteries, but find their warranty is pretty worthless with the requirment to RMA back to China. You just right it off. In 16 orders those batteries and one 9 gram gyro were defective.

Bill
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Old Sep 30, 2008, 10:25 AM
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Quote:
Originally Posted by Prof100
My goal would be to use both gyros to experiment with pitch and roll control. How are these wired into the system?
One Gyro plugged into the receivers aileron output, the other to the elevator. Mount them so that they act in the correct axis. Then you just plug the v-tail mixer into the gyro outputs, and servos to the mixer output.
This way the gyros will work in their separate axis' and the mixer will convert it for your elevons.

I'm going to build a Gripen with pitch gyro on the canard, and maybe one for roll too!
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Old Sep 30, 2008, 11:40 AM
Just one more flight...
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Another tip on putting a gyro or 2 on your plane:
Say you want to move the CG way back on your fighter jet to get better maneuverability and use of your flaps and you are using a gyro on the pitch to do it. The plane is now going to want to fly with some DOWN trip to fly level (to float the tail back up cause the nose wanted to pop up). So you got to make sure that you then trim the plane by adjusting your pushrods to have the right amount of down trim to fly level, THEN let the gyro take it from there.

For example, in the video I posted you can see that I still was able to fly the jet with all 3 gyros turned off (it was hard to control but it was still trimmed in right for a tail heavy CG with DOWN elevator and canards as my "zero" point).

Because the bottom line is you just want the gyro to merely help you do what the plane is already capable of doing. In this example, to fly being tail heavy using some down trim to counter it, which is then perfected with the gyro. This way, the gyro just has to make very small adjustments when correcting your plane for you, because you have it trimmed in close enough where it needs to be fly under control... I hope all that makes sense.
Dave
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Old Sep 30, 2008, 12:50 PM
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Good point!
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Old Sep 30, 2008, 01:41 PM
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That make complete sence! I feel plane are easier to control being on the tail heavy side. They are much more predictable at slower speed (IMO).
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Old Sep 30, 2008, 01:54 PM
Just one more flight...
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Hey alright, glad that made sense! Yes, I have found that too with tail heavy CG. Its the easiest to hover and go high alpha being tail heavy as the plane is now naturally comfortable with its nose up, thats where it wants to be anyway. Its just the level flight and especially slowing down to land is where the tail heavy CG cause the plane to be extremely hard to control - and thats exactly where the gyros come in!
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Old Sep 30, 2008, 02:15 PM
Just one more flight...
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To kinda summarise how my gyros are helping with the SU-35:

1) YAW GYRO is connected to both rudders and yaw VT motors:
Level Flight: This just helps keep my turns much cleaner. This is what gives it the look that its "flying on rails" when its turning.
High Alpha/Hovering: They are a big help here. The plane wants to slide off to one side, they hold it up steady for me. I could not hold it in a hover without them.

2) ROLL GYRO is hooked up to both ailerons (that flip UP in high alpha to act as spoilerons) and both VT elevons in the back.
Level Flight: This plane can roll way too fast. I have to use dual rates to calm it down, but with the gyro I don't. Its slow and steady on the roll and always in control, yet I can still spin it when I want to. Whats so cool, is when I am done doing a roll, the gyros grab the plane and just STOP it from rolling the second I take my hands off the stick! Very cool to see!
High Alpha/Hovering: They help big time here, I would not be able to get past 40 degrees or hover without them. The wings start to wag back and forth without the gyro as you can see in myearlier videos on YouTube.

3) PITCH GYRO is hooked up to just the canards in the front. Do to the other 2 gyros already installed and the mixers, I can not hook this up to the elevons/VT in the back, but thats ok.
Level Flight: Being tail heavy, the plane always wants to "pop up" when going to slow or too fast. I gave the canards the maximum amount of throw the gyro dial had. This allows the gyro to really move the canards alot and take pitch control of the plane. This is most seen while landing. When the tail heavy jet slows down to land, it flips up, stalls, and crashes without the gyro. With the gyro the plane lands itself! Seriously, I landed the plane with the gyros on simply by powering down! My hand was not even on the pitch stick!
High Alpha/Hovering: I don't need the pitch gyro much in high alpha. Because I have the CG back, the canards and spoilerons now facing back into the wind by hitting my Ch5 and Ch6 high alpha switches, then have a pretty stable platform as far as pitch. Basically, at this point, the plane wants to have its nose up, so I don't have to fight to keep it there, its just the roll and yaw that wants to slip out as mentioned and corrected above.

Dave
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Old Oct 01, 2008, 07:15 AM
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Awesome project Dave.
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Old Oct 01, 2008, 11:27 AM
Ted M
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Ann Arbor, MI, USA
Joined Feb 2007
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Quote:
Originally Posted by Prof100
I, too, have the EK2 0704A gyros (a pair of them) NIB that were destined for a AP but never used. The price I paid was closer to $30. I would like to use them on my elevon planes. I need a quick "how-to" review to install in an elevon plane. My elevon planes currently uses the radio for elevon mixing which is a no-no for gyros. I do have an old FMA direct mixer I can cannabilize from a flying wing I never got around to flying. My goal would be to use both gyros to experiment with pitch and roll control. How are these wired into the system?...
I think you'll have to use 2 mixers if you want to control a mixed elevon tail and you may still have issues if you can't change the servo direction - maybe using a servo-reverser? - because a plane is typically set up symetrically and that means that the 2 elevon servos will have different 'polarities' as far as the elevons are concerned. I'll try to explain that although I know a picture would be better

I'm assuming that you have set it up so that there is one elevator and 2 aileron outputs from the receiver.

First set up with no Gyro
Get rid of the mixing in the transmitter and then connect the elevator output of the receiver to both mixers and then aileron1 and aileron2 to each mixer respectively and the mixer outputs to the rear servos. You'll have to make this work before you can move on to adding the gyro.

Adding EK2-0704A Gyro
For pitch control, fit the gyro close to the CofG, label upwards and with the gold pin connectors facing the front of the plane. Unplug the elevator Y cable from the receiver and plug it into the Gyro gold pins connector, plug the 3 wire plug from the gyro into the elevator channel of the receiver. The single wire can be left disconnected (my current state) but I'm not sure if that leaves the gyro in HH or rate mode - it's definately one or the other. If you have a spare channel then you can plug the single wire into the signal wire of that channel and set up a swicth to control the channel output. You can then remotely switch the gyro between HH and Rate mode, 1 extreme is rate and the other is HH - the gain is ALWAYS set by the gain pot and cannot be remotely controlled. Some people say that you can ground the single wire and it will be in HH mode - not tried that but if it's true then you could just plug it into a spare receiver chan so that it goes to the -ve connector.

Set the gyro gain pot to center and power up - don't move the plane while you're powering up or you'll upset the gyro initialization. Now pick up the plane and rock it in pitch watching the control surfaces; they should move to counter the movement you are making to the plane e.g. if you move the plane's nose down, the rear surfaces should move up. If this is the wrong way round, switch off and re-position the gyro so that the gold pins face the back of the plane, still label up. Alternatively you could fit the gyro pins forward but with the label facing the bottom of the plane. Either will reverse the control logic (FYI, expensive gyros have reverse switches.)

The controlled axis is through the gyro sides, in other words, if you hold the gyro so that you're looking at and reading the label, the controlled axis is in from the left and out from the right side of the gyro.

If you have too much gain, the plane will hunt in the controlled axis, not enough and control response will be sluggish. Start at 50% gain (half way round the gain pot travel) and then increase slowly until you notice oscillation (hunting) and then back off slightly. I guarantee that if you start at 100% then the plane will be almost uncontrollable.

These gyros have a tendency to creep until they 'warm up', if after you switch on (remember not to move the plane) the servo starts to slowly creep in one direction, then you need to play with the elevator trim until the creep stops; if it creeps off to one end, move the elevator control until it centers and then keep playing with the trim until it's stable in the middle.
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Old Oct 01, 2008, 01:23 PM
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USA, PA, Media
Joined Apr 2005
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Thanks Gandolf, now I "have" to order 3 gryos and 3 mixers (why by 2 when you can have a spare) and 3 mixers.... plus they are out of stock at UH and their shipping is higher than I like (more than made up for in the price).....

I didnt know I "needed" gyros until 3 days ago when i stumbled across this thread.... and if I am placing an order, i might as well get stuff for my next plane... but i dont know what that will be yet... hahaha... *sigh*

seriously, thanks for the explanation, for gyro noobs like me, thats a help.

rick
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Old Oct 01, 2008, 05:06 PM
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Canton, Michigan USA
Joined Jul 2007
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Quote:
Originally Posted by Gandalf_Sr
I think you'll have to use 2 mixers if you want to control a mixed elevon tail and you may still have issues if you can't change the servo direction - maybe using a servo-reverser? - because a plane is typically set up symetrically and that means that the 2 elevon servos will have different 'polarities' as far as the elevons are concerned. I'll try to explain that although I know a picture would be better

I'm assuming that you have set it up so that there is one elevator and 2 aileron outputs from the receiver.

First set up with no Gyro
Get rid of the mixing in the transmitter and then connect the elevator output of the receiver to both mixers and then aileron1 and aileron2 to each mixer respectively and the mixer outputs to the rear servos. You'll have to make this work before you can move on to adding the gyro.

Adding EK2-0704A Gyro
For pitch control, fit the gyro close to the CofG, label upwards and with the gold pin connectors facing the front of the plane. Unplug the elevator Y cable from the receiver and plug it into the Gyro gold pins connector, plug the 3 wire plug from the gyro into the elevator channel of the receiver. The single wire can be left disconnected (my current state) but I'm not sure if that leaves the gyro in HH or rate mode - it's definately one or the other. If you have a spare channel then you can plug the single wire into the signal wire of that channel and set up a swicth to control the channel output. You can then remotely switch the gyro between HH and Rate mode, 1 extreme is rate and the other is HH - the gain is ALWAYS set by the gain pot and cannot be remotely controlled. Some people say that you can ground the single wire and it will be in HH mode - not tried that but if it's true then you could just plug it into a spare receiver chan so that it goes to the -ve connector.

Set the gyro gain pot to center and power up - don't move the plane while you're powering up or you'll upset the gyro initialization. Now pick up the plane and rock it in pitch watching the control surfaces; they should move to counter the movement you are making to the plane e.g. if you move the plane's nose down, the rear surfaces should move up. If this is the wrong way round, switch off and re-position the gyro so that the gold pins face the back of the plane, still label up. Alternatively you could fit the gyro pins forward but with the label facing the bottom of the plane. Either will reverse the control logic (FYI, expensive gyros have reverse switches.)

The controlled axis is through the gyro sides, in other words, if you hold the gyro so that you're looking at and reading the label, the controlled axis is in from the left and out from the right side of the gyro.

If you have too much gain, the plane will hunt in the controlled axis, not enough and control response will be sluggish. Start at 50% gain (half way round the gain pot travel) and then increase slowly until you notice oscillation (hunting) and then back off slightly. I guarantee that if you start at 100% then the plane will be almost uncontrollable.

These gyros have a tendency to creep until they 'warm up', if after you switch on (remember not to move the plane) the servo starts to slowly creep in one direction, then you need to play with the elevator trim until the creep stops; if it creeps off to one end, move the elevator control until it centers and then keep playing with the trim until it's stable in the middle.
Gandalf Sr.

Wow, I need to digest this. I am short one mixer. Prices range from $3 (UH/HC/HK plus shipping) to $30 with Tower having a couple in the $12 to $15 range plus shipping. My plan currently has the battery mounted on CG so we can only mount left and right.

Like I said, I need to think it through.

Bill
(Go Blue)
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