edge 3644

Hi,

I want to improve the tail stability when hovering my acro planes, simultaneously rudder and elevator. I have never used them before. Please advice which gyros are worths considering.

Thanks in advance

Robert

twinman

My Feedback: (2)

Cannot suggest best brand for this application, but go to rcwarbirds.com
Gyros are covered in the flying forum and the twins forum. Just completed tests with heading hold gyro in a plane, detailed in twins forum. Works fantastic, with warnings about turning it off in the forum.
You will need two separate gyros for the rudder and elevator with separate controls for rate control.
Good Luck

Bill Mixon

Hi Robert,

I have not used one, but if I were to buy any gyro it would be the Futaba GYA 352 Dual Axis.
A lot of people have had good luck and really like the Hobbico airplane gyro for hovering. It is also realitively cheap. But remember as Twinman mentioned you need two of them and it would also be a good idea to have two switchs to cut the rate or turn them off for "normal" flight. If you use any kind of heading hold or lock gyro such as the Futaba AVCS series you must have some means of remote adjustment from the transmitter. It is almost impossible to fly a plane with heading lock gyros on both the rudder and the elevator.
For example if you tried to make a left turn using only aileron and elevator the rudder gyro would sence that the plane is yawing to the left and would input right rudder. The same is true for the standard "rate gyros" but, they are much less sensitive and would not correct as much as the other gyros.
Also remember: If you input rud or elev in the wrong direction when hovering, the plane will go in that direction regardless of the gyro. So you really need to know which input is needed.
I learned to torque roll without gyros and have found that flying other members planes that do have gyros to be more difficult in a way.

The price of the 352 is about $280.
Which is like buying two gyros for $140. The advantage is that you only have one unit to mount.
Below is a link, have a look at it.

http://www2.towerhobbies.com/cgi-bin...1&I=LXBBE6&P=7

Good Luck

Bill

twinman

My Feedback: (2)

Yes, I would agree, with Bill, that practice is the best and purist method..and also the longest and most difficult.
Flying with a gyro on the rudder is no different than standard flying....except ground loops and unexpected turns on take off and landing are, for the most part a thing of the past...you do use the left hand for more than the throttle don't you? If not, them Bill is correct that the gyro will fight you. If you normally use rudder and aileron for turns, the rudder input cancels the gyro action until the control is centered. Landing is a no brainer, even in a cross wind.
The heading hold gryo is a completely different animal and is the most responsive for hovering, but MUST BE SWITCHABLE TO STD GYRO SETTING IN THE AIR. Do not attempt to fly heading hold in normal flight!!!
I have tried the standard gyro for the elevator, and it can get more interesting. Suggest that you mix the elevator input to reduce the gyro response as the elevator is given the up command or turn it off for normal flight....scared myself bad once!!
Do they work.....yes, but review the operational characteristics before flying.
t
Told you twins make you crazy!!!!!

edge 3644

Thanks Twinman and Bill for your advice.

ROBERT

amcross

My Feedback: (2)

Robert,
Just to clarify one thing -- a heading hold (AVCS) gyro will continue to try to correct until it gets back to its regular heading or you tell it this is now your desired heading. A std/piezo gyro will just say "hey something moved me for x seconds, i'm going to move back for .x seconds" and then stop trying. so you can use a normal gyro comfortably for normal flight, whereas a heading hold will try to turn the model back around to where it was going if you're not using rudder for your turns.

All or nearly all AVCS gyros have the ability to be switched in flight from heading hold to normal. Heli pilots fly around in heading hold all the time, but they also use rudder to turn their models, unlike most airplane pilots who just cheat and do aileron/elevator turns. Therefore, most airplane pilots NEVER fly in heading hold/AVCS except for hovering and take off/landing.

twinman

My Feedback: (2)

I agree with AMCROSS, but to do the post in RCWARBIRDS I did acutally fly the plane, I would reinforce the warning about using Heading hold.
It is very aggressive for hover on an airplane, but only use it, by switching on as you go to hover and immediately switch off for ANY other flight pattern.....including landing.
The danger is that if you fly coordinated, using the rudder with alerons for normal flight, the heading hold position of the gyro will assume the new rudder adjustment and try to hold it.
Can you imagine the problems during a landing approach!!
USE THE HEADING HOLD SETTING ONLY FOR HOVERING!!!
Normal setting with normal gyro setting is fine for everything else, just fly coordinated with the rudder and ailerons. You will love landing with a looping monster with a gyro.
Good Luck,
Twinman

amcross

My Feedback: (2)

Respectfully, Twinman, many of the scale pilots DO use it for landing approaches...they can then be sure that a gust of wind won't knock the model of course as it goes right where it belongs. Perhaps yours was turned up so high that it was overly aggressive?

If coordinated turns are used, like the heli pilots, probably 95% of the heli boys fly in nothing but HH with a good HH (AVCS) gyro. When you use a proper coordinated turn, the gyro picks the new heading you aimed it to with the rudder input, and stays there. Now, if you goof and do an aileron/elevator turn, the HH gyro will turn that model right back around to the last heading you told it you wanted...facing the opposite direction!

Just wanted to clarify, it is not an 'evil' or "sure crash" to use HH on an aircraft in normal flight, but it requires the user to really understand what the gyro does and to use it properly and safely.

edge 3644

I appreciate much your advice

Thanks

Robert

twinman

My Feedback: (2)

To AMCROSS. Agreed, but if the rudder is not deliberately recentered after any movement, not just centering the rudder stick on the transmitter, the model will turn unexpectly in the direction of the last correction, and that is what I wish to warn people about. The rudder, with Heading Hold on, will not recenter as you are normally thinking it will.
Yes, I used a Futaba GY 401 for the test
I also use two gryos to stabilize two large P-38's, but after this test they are not and will not be heading hold, as I feel is over kill for the average flyer.
Do I recommend gryos? Yes for many applications ( I am sure the Purists will get me for that one!) and the Heading Hold, with warnings, is superior for hovering to a conventional gryo.
I am humbled in your presence!!!

amcross

My Feedback: (2)

Hi, twin! thanks for the continued discussion! I'm just not sure we're understanding each other 100%. I agree 100% that caution is required when using the heading holds; i simply don't want modelers to think they CAN NOT be used in forward flight, as they are used that way by heli and also "fixed wing" modelers the world over every day.

If the coordinated turn is done correctly, or any other turn, etc, then simply centering the rudder stick is sufficient, and the model will maintain the new heading provided. The ideal example is a rudder-only flat turn, with aileron/elevator used only to keep the model flat.

I concur, that for many modelers a heading hold gyro is not needed. However, if hte application is to keep a twin straight on the runway on takeoff, or any scale model for that matter, or for hovering, then the heading hold function makes all the difference in the world.