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egrave1 12-27-2013 05:20 PM

gyros
 
Not knowing that much about gyro. I been looking at some but don't know What I am looking at What is some of the info I should be looking for ????

fhhuber 12-27-2013 05:29 PM

There are 2 basic types of gyro stabilization
Rate gyros attempt to limit the rate of change of direction.
Heading hold gyros attempt to lock onto a direction.
Both are over-ridden by control inputs.

Rate is better for most fixed wing purposes as they will tend to damp out much of the effect from wind turbulence but allow the normal minor drifting associated with "straight and level" flight.

Heading hold tends to be more useful for helicopters, especially for adavnced aerobatics.

The newer 3- axis gyros can be very nice for assisting in learning to fly, if they are set up correctly. Generally this means an experienced RC pilot needs to fly the plane and make adjustments to the gyro.
An improperly set gyro can be worse than having no gyro.

You also get exactly what you pay for when getting a gyro. Cheap tends to be unreliable and/or difficult to properly adjust.

pizzano 12-28-2013 01:20 AM

Quote:

Originally Posted by egrave1 (Post 935363)
Not knowing that much about gyro. I been looking at some but don't know What I am looking at What is some of the info I should be looking for ????

What are you looking to use the gyro on....heli, fixed wing, quad.....?

The size of the craft will make a difference as to the of type application. The type of reciever and servos you intend to use will also have an impact on the gyro's performance.

Quality is always the best choice for any Gyro....that means it will cost a little more and most likely be a brand name like Align, JR, Futaba, ect.

solentlife 12-28-2013 03:42 AM

What to look for ? Is it for stabilisation of a fixed wing or for general Heli style use ? Is it for 1 axis, 2 axis or 3 ?

In Heli single axis :>

Ability to be able to adjust settings direct on Gyro as well as via Tx ...

Ability to switch from Rate mode to Heading Hold by Tx

Ability to alter gain while flying by Tx

Whether only suitable for Digital Servos or both analogue and digital.

There really is no need to spend great amounts on a gyro for basic sunday flying. But if you are looking for precision and special uses - then of course look at upper market entries like the Quark.

For general use, gyros such as the GY208, GA-250, GA-280, as examples ... with even the budget Etech G105 ... all work.

I have the $10 Etech G105 on both my 450 Heli's and they work well. I don't need ultra precision flight and they do a good job for general sport flying, with excellent direct and via Tx settings adjustments.

BUT one comment I will make : If you are thinking of a gyro to fit to an unflyable or difficult to fly model - think again. A gyro does not make anyone an instant flyer. It is not a cure for an unsuitable model or a bad model. Ideally the model should be trimmed and flown and proven before committing to gyro. A gyro is an AID to flight control - not an answer to it.

Nigel

AEAJR 12-31-2013 02:56 PM

Gyros are tools and like every tool they are made for specific purposes. if we don't know the application we really can't tell you much beyond the excellent post made by fhhuber.

ICE-MAN 01-21-2014 11:50 AM

Here is how I see the rate gyro for a fixed wing aircraft: In normal flight, in perfect weather conditions, and with a perfectly designed aircraft the action of moving the sticks will cause the control surfaces to move. This will result in perfectly predictable results to the aircraft attitude. The aircraft attitude will move to a new position as required. However, in the real world there are disturbances primarily from wind gusts, and possibly from badly balanced or out of alignment or badly designed air frames, from badly aligned motors / props too. (And normal prop torque). When any un-commanded movement takes place the gyro will immediately correct for it by moving the control surfaces to counter such a change. It does this by measuring the angular acceleration of the air frame (all 3 axes ideally). And if there are no movements from the control sticks to command such motion the gyro will counter act them to keep the aircraft stable. With the good quality gyros, more than this: If the control stick is moved to a certain position, the gyro will know the type of attitude movement that is required. If the attitude movement is more (or less) than this (due to the real world disturbances mentioned above), then it will again counter these un-commanded movement forces. The result is like flying in perfect conditions and with a perfect airframe regardless of weather and design (within limits of course). In reality users comment that the aircraft flies like a much larger plane.

JetPlaneFlyer 01-21-2014 12:09 PM

But they arent without problems.

For instance, if you try to do a simple gentle turn using ailerons the gyro will fight the turn. It does this because it sees an uncommanded change of heading (yaw) when only aileron (roll) was input. This makes ordinary turns quite awkward requiring exagerated aileron and rudder co-ordination. I found this really tiresome when I tried a 3-axis gyro.

Also any aerobatics such as spins and snaps and tumbles etc that have the plane moving in an orientation that was not strictly as per control input will be resisted by the gyro, this too is annoying.

In the end I found I liked my planes better without the gyro.

dahawk 01-21-2014 01:42 PM

For me, a gyro is simply a confidence builder for flying in wind. When it gets over 10kts, I get nervous , especially with my foam planes. I do keep the gains set fairly low. They also help on hand launching.

I have an Ice Man gyro and frankly, its the gold standard of the gyro world. Also have an Orange combo rx/gyro and it works fine.

Are they a cure all for lousy flying? No.

ICE-MAN 01-22-2014 02:04 AM

Quote:

Originally Posted by JetPlaneFlyer (Post 937699)
But they arent without problems.

For instance, if you try to do a simple gentle turn using ailerons the gyro will fight the turn. It does this because it sees an uncommanded change of heading (yaw) when only aileron (roll) was input. This makes ordinary turns quite awkward requiring exagerated aileron and rudder co-ordination. I found this really tiresome when I tried a 3-axis gyro.

Also any aerobatics such as spins and snaps and tumbles etc that have the plane moving in an orientation that was not strictly as per control input will be resisted by the gyro, this too is annoying.

In the end I found I liked my planes better without the gyro.

Regarding the gentle turns, this seems rather odd, normally the gyro would sense if there's any slip in the turn (ie a yaw) and make the turn better by countering it.

On your second point, yes I agree there can be some issues here, normally with such aerobatics the gyro should be gain reduced or switched off.

fhhuber 01-22-2014 04:36 AM

depends if its a rate or heading hold gyro as to the actual effect

Gyros do not detect slip. They detect heading change.

A heading hold gyro on the rudder of a fixed wing model would make the rudder try to hold heading when you command a banked turn. Result will be the rudder opposing the turn, potentially snap-rolling the plane in its attempt to overcome the detected change of heading.

A rate gyro will similarly oppose the heading change but depending on its gain setting might simply help prevent the nose from dropping.

ICE-MAN 01-22-2014 05:06 AM

Yes, by slip I meant a rotational change on the aircraft yaw axis. (Incorrect terminology on my part - sorry!) Which as you say is heading change. For those who may not know, the gyro actually only measures rate of rotation about a particular axis. A heading hold gyro will add up all these small changes on the yaw axis to estimate the heading, allowing it to then correct for it. The rate gyro will not do all the adding up of the rate changes and so will not have any idea about the actual heading and so will not correct for it. Instead it corrects only (but immediately) for the rotational changes, thus as you say helping to prevent a nose drop, also known as keeping the plane in balance. Incidentally, I understand the use of a heading hold gyro on helicopter, but I'm not so sure why someone would want to use it on a fixed wing aircraft.

JetPlaneFlyer 01-22-2014 05:52 AM

FWIW, the giro i was using was a fixed wing specific one, the FY-30A, not a lash up using a heli giro.

The rudder fighting the turn problem shows itself more if you have the gains set high, but even with low gains it must be there , just not so obvious. The giro is only doing what it's designed to do and that's to oppose un-commanded movement of the model is any of it's three planes of freedom. As far as the giro is concerned aileron is purely for roll so any change of heading will be opposed.

Regarding the turning off and on... Yes, you can do that, the giro I had allowed it to be done in-flight. But constantly turning the giro on and off every time i wanted to do certain aerobatics was a pain. I found myself just leaving it off all the time as constantly flicking switches got in the way of my enjoyment of flying the model.

Of course these are only my personal experiences, others may see it differently. If you have the gains (esp. rudder gain) set low and your flying is limited to circuits and simple 'single plane of freedom' aerobatics (loops, rolls etc) then the experience would be very different.

fhhuber 01-22-2014 08:15 AM

If you want to leave the gyro on for basic "coordinated flight"... mix some rudder in with aileron and then the gyro will see the command. The gyro will still damp sudden swings even during the turn, but it won't fight you as much.

JetPlaneFlyer 01-22-2014 09:44 AM

Quote:

Originally Posted by fhhuber (Post 937803)
If you want to leave the gyro on for basic "coordinated flight"... mix some rudder in with aileron and then the gyro will see the command.

Good call, that would certainly address the issue in normal flight.

Personally I didnít want to mix rudder to ailerons because the model in question was aerobatic and the mix would have interfered badly with many aerobatic manoeuvres.

Having the mix switched is possible but just gives yet more switches to flick every time you want to do aerobatics.

cyclops2 01-23-2014 01:01 AM

I am laughing about all the ins & outs of using a gyro. :)

I remember the huge one on my WW II destroyer.
They truly do resist changes. To the extent, that one in a storm, ripped out of the mounts & went thru the side of the ship !!


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