megafly

Hi guys, I have a Jr 370A laying around, do you think I can instal it in my L39 (feibao)?
If yes is best to instal in the aileron or rudder channel?


Thanks a lot!

FenderBean

you always want the gyro as close to the center axis of rotation. Down the middle and around CG. Just like in a heli you want it as close to the mast as possible.

megafly

Do you think is better in the roll axis or the yaw axis?


Thanks.

HarryC

My Feedback: (1)

Not true. It is totally irrelevant where you put it in the model. You can put the gyro out at a wing tip if you want. All parts of the model rotate at the same angular rate. If they don't, the model is coming apart!

HarryC

My Feedback: (1)

Fly it first and see if it needs one or not.

madmodelman

It'll need one, on the rudder, unless like me you don't care about a bit of wobble!

FenderBean

totally disagree with you but hey its all good, yeah it will work any place you put it but will give better control and be smoother the closer to axis of rotations.

HarryC

My Feedback: (1)

You are not disagreeing with me, you are disagreeing with mathematics. Where you put the gyro is totally irrelevant, it makes no difference and it is not smoother at the centre of rotation.

David Gladwin

Please Fenderbean DONT tell Boeing or Airbus !! The sensors for the yaw dampers are nowhere near the C of G, in fact they are very close to the nose, in the E and E bay.

As Harry says you can put the sensor ANYWHERE in a rigid model. ALL parts rotate at the same angular velocity so sensor location is irrelevant as angular rotation is what is being sensed and opposed, therefore they work equally well wherever they are located !

The only reason it is located at the mast in a model heli is to minimise vibration effects.

David Gladwin.

erbroens

Hey guys, I think that megafly is trying to ask where is more useful to use a gyro, in the roll or in the yaw axis in his L-39.





Enrique

megafly

Yes Erbroens, you are right, sorry if I didn't explained correct.
But what HarryC told is true, "fly first", but I think I'm goind to put the gyro in the aileron, the L-39 has a short wing.

erbroens

anytime, and you may also want to take a look on this thread for some useful information:


http://www.rcuniverse.com/forum/m_82.../anchor/tm.htm


Enrique

BarracudaHockey

My Feedback: (11)

The only real consideration is not to put it in a vibration prone area. Where on the model doesn't make a difference.

WhoDaMan

My Feedback: (164)

what do you see in the nose of this Fiberclassic F-86

FenderBean

if you put the sensor on the wing tip vs the center ( big extreme) it will still work! but the gain of the gyro will need to be much less than if it was closer to center. This is because the wing tip is further out on the arm, 5 inches of travel on the tip would equal say 1 in closer to center. think of the gain like servo resolution, if you dont believe me try it some day.
Thats my experience so we can agree to disagree.
Keep gyros away from carbon fiber, unless u use a metal bracket under it, keep it away from heat, and new gyros are extremely sensitive to vibration. A jet doesnt produce enough vibration to bother it, I would be more worried about heat.

BarracudaHockey

My Feedback: (11)

It still turns at the same rate, the arm is irrelevent. If the nose turns 10 degrees then you'd better hope everything else turns the same amount at the same rate of turn

Thats all gyros care about, the angular displacement.

Also, carbon doesn't matter, they just need to be flat to the axis they are controlling and away from vibration which will cause precession.

OliverJacob

My Feedback: (12)

In a heli the placement makes some difference, but it'll still work in any place.
The further you are from the center of the rotating axis, the faster the movement will be - thinking in absolute speed, not degrees per second.
Hence the force the gyro experiences will be greater and it tends to over steer.
But the gain setting will compensate for this.

Rudder or ailerons - fly the thing first and see if a gyro is needed at all, then I'd start with a low gain setting and gradually turn it up.

FenderBean

Wrong, if this was true then the length of a servo arm on your rudder servo would not matter, but as a heli guy know better. You said angular displacement, thats exactly right and length from center does matter because the further u move away from the mast on heli cause great angular numbers.
Oliver thats what im saying gain will compensate unless you go to low then it start slowing the response speed. I am sure anywhere you put the gyro in a jet will work fine, but it will works best and perform best as I described.
anyway good luck with the gyro feel free to google it, plenty out there to read on how a gyro actually works.

JackD

My Feedback: (4)

Fender,

For a second think that what others are saying might be right: gyros react to angular acceleration. Angular acceleration is constant on any plane. It is not a function of distance from the axis of rotation.
What varies from the center of rotation is tangential acceleration, but that is irrelevant to the gyro.

Look at it another way: if you turn your airplane 360 degrees, no matter where you put your gyro , it will turn 360 degrees, right? and if you do it in a second, the angular velocity across the whole plane was 360degrees/second, right? and if you change the speed, the acceleration will be the same across the whole plane, right? so what does the gyro cares where it sits?

I know it might not be totally intuitive at first, but trust us, it is absolutely correct

gotta love this tech/physics chats...

later
Jack

JackD

My Feedback: (4)

Megafly,

I flew a skymasters L39 and didnt need a gyro on the rudder. So if you have a spare gyro, I would probably try it on the ailerons, since it is kind of useless on the rudder.

But it doesnt hurt to try both a see what you like best

rctech2k7

My Feedback: (1)

FenderBean, your post became heated discussion, don’t worry about that, it’s not a wrong answer, you can say that as I can also say that it’s in the center of lift somewhere in the center of wings and the fuse. Let’s say center of roll and pitch axis. However, the things they've said are right, wherever we go on the line of axis it’s all the same angle or slope, the rate that the angle is changing are the same all throughout the axis. The only difference they have is the arc generated. The arc length is longer as it goes away from the reference point or center but the rate of change with respect to the center are the same, meaning directly proportional. Reference point and intersection of more than one axis could be anywhere cause each axis can rotate independently with the other axis on its dimension... So far I’m still learning with this micro tech gyros but IMO it detects rotation about an axis that is used to maintain orientation.

PaulD

My Feedback: (39)

I put one on the rudder of my Carf Tutor and I sure like it there. Just mounted it to a convenient location on the equipment tray, set the gain up to where I liked it and went flying.

PaulD

rctech2k7

My Feedback: (1)

To answer OP, for me is to use one axis primarily on ailerons, second is depending or your requirements. For takeoff you might need directional stability but not in the air for banking turns. For pitch sensitive aircraft you might need one otherwise better to have natural stability for now...

HarryC

My Feedback: (1)

Oh FB, you really have been delving into the "Book of Modeller's Myths"! That's all untrue, I must say that one about c/f is a new one though.
Someone has seriously misled you about how a gyro works. A gyro does not sense movement. It only senses a change in angle. A gyro placed at the centre of a wheel sees exactly and only the same change in angle as a gyro placed on the rim of the wheel.
Did you know that if you place a gyro on a sheet of carbon fibre and rub it with aromatherapy oils while chanting a secret incantation known only to Freemasons it turns into a 3 axis gyro.

mick15

At least it's not your print cartridge you're wasting H.

m