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Old Feb 06, 2012, 01:01 AM
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Does gyro help dynamic soaring?

I have heard that gyro helps stabilize the plane when it encounters a sudden turbulance during dynamic soaring.

When the plane is disturbed by turbulance, gyro returns the plane to an original atittude before disturbance.

After I lost a plane recently in turbulant air during dynamic soaring, I thought it might be a good idea to use a gyro.

If anyone is using a gyro now in DS, I would like to find out the brand name particularly suitable for DS and where to buy it.
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Old Feb 06, 2012, 01:31 AM
Where is the inspiration
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Hello John

Yes a gyro can help smooth out the back side. It can remove alot of the shear layer effect on the model.
Deckit and myself have used the Futaba GYA351 aileron gyro (2 aileron servo input and outputs).

This is however a controversial issue and I am sure there will be some negative posts. But I think the 100 is worth it to save a 500 to 1000 model.

Will
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Old Feb 06, 2012, 01:40 AM
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Originally Posted by wdeighton View Post
Hello John

Yes a gyro can help smooth out the back side. It can remove alot of the shear layer effect on the model.
Deckit and myself have used the Futaba GYA351 aileron gyro (2 aileron servo input and outputs).

This is however a controversial issue and I am sure there will be some negative posts. But I think the 100 is worth it to save a 500 to 1000 model.

Will
What about elevator gyro?

Isn't there a 3 axis gyro? for aileron, elevator and rudder?
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Old Feb 06, 2012, 02:00 AM
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It is only needed/useful on the roll axis.
There are 2 and 3 axis gyros but they aren't tailored for airplanes so they
only have one input/output per channel, so can't handle elevons/flaperons/spoilerons/differential.
The ACT Fuzzy SMM and Futaba GYA351 are both made specifically for airplanes
and have a single axis gyro with two inputs and two outputs that work with
all the above mixes. They also have remote adjustable gain, and work in both rate
and HH mode (HH is much better for DSing). They're both not cheap.
And no, there's no Chinese made equivalent.

ian
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Old Feb 06, 2012, 03:16 AM
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The new A3X systems that Horizon is putting in their micro airplanes seems pretty interesting. It's essentially a 3-axis fly-by-wire system intended to make a micro plane handle like a bigger airplane, even in wind (they even have it on that tiny little scale sailplane they just released). I dunno if they have any plans to offer an upscale system for large sized RC planes, but it'd be interesting, I think.
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Old Feb 06, 2012, 07:05 AM
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Quote:
Originally Posted by Daemon View Post
It is only needed/useful on the roll axis.
There are 2 and 3 axis gyros but they aren't tailored for airplanes so they
only have one input/output per channel, so can't handle elevons/flaperons/spoilerons/differential.

ian
What about the 2-axis futaba gya352? A friend is installing one in an M60 for elevator & flaperon.

I am about to try the single-axis 351 in an MCT.
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Old Feb 06, 2012, 02:26 PM
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Roger (kahnx) has used cheap heli gyros, one per aileron. They seem to work really well. I saw him DS his no gyro thorn and the air was pretty bumpy, then get out his very light gyro'd bird and it seemed to look like a much heavier plane, as in much more stable than it should have been. Roger's light D60 has I think the futaba gyro daemon mentioned and it seems much more stable than my d60 with tip weight. He hasn't convinced me to put some in mine yet but there is definitely a big advantage in stability and less likelyhood of crashing due to turbulence IMO
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Old Feb 06, 2012, 03:11 PM
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Can only use two gyros (one on each aileron) if they're rate mode, which means
need to tweak the gain down for the highest speed you'll fly, otherwise it'll speed wobble.
Rate mode will soak up general turbulence, but HH mode will always return the plane
to the original attitude even in the very worst air (as long as the plane has sufficient
airspeed).

The GYA352 is a nice gyro, but only one input/output per gyro axis, so it will
not work with elevons/flaperons/spoilerons/differential. I've been flying gyro'd DS planes
for a few years and I have never felt the slightest need to have stabilization on the
pitch axis (elevator). I can't even imagine why people think it'd be useful there.
In fact, I think HH mode on elevator would produce some strange behavior.
You'd pull up to set the turn radius, and then have to center the stick to hold
that radius. Could be kind of confusing as you'd have to actively push and pull
every lap to keep the plane from drifting back. I know some people trim their planes
to sort of fly like that, but many of us like to either always pull a little, or always
push a little, and you can never do that with a HH gyro (any continuous input, will
result in continuous increase in response).

ian
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Old Feb 06, 2012, 03:42 PM
Arrarrar!
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My concern with gyros and learning, Roger and I have debated each other about it a bit, is that if you learn with a gyro you may become 'lazy?' and over reliant on the gyro. When you switch it off you may find your reactions aren't tuned enough to deal with random gusts etc and you may lose the plane that way anyway. Rog is always trying to convince me to put a gyro in one of my planes and my argument is always that I want to get better at flying non gyro'd before I commit to one. I think if you do have a gyro'd plane, you need to practice flying equally with it on and off so you dont become over dependent on it.
I hope that makes sense,
Josh
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Old Feb 06, 2012, 04:31 PM
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That's one way to look at it. The other is that with the gyro you can choose to push harder,
faster, lower, and in crappier air. Explore the limits of the groove, with less fear, and then
use that knowledge to your advantage when flying planes without. For the most
part I've found that every DS aircraft I've flown, has advanced my skill in some way.
Last big day at Jones Pass this last season, I flew 263mph on my weak side
(clockwise circuits) with the gyro'd D60 and then turned around at flew 307mph with
my Wizard, which is my PB for the hill, and my fastest weak side speed. Can be
useful when a 60oz 60" plane feels like a 200oz 100" plane in the air.


There's also something to be said for simply accumulating more hours in any DS groove
(good air or bad) with a stable plane. Same reason those smooth SoCal grooves
crank out good pilots.

ian
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Old Feb 06, 2012, 04:41 PM
Arrarrar!
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Hey Ian, Im totally for gyros in the right situation, but I really think a new flyer needs to do their 'apprenticeship' without them. I fully understand that gyros dont fly the plane for you and you still need a lot of skill, even to nderstand how Ds works.
I may get some/one into one of my planes some time soon for the exact reason you said, as we have a couple of slopes with really low shear and to get under you pretty much have to skim the wingtip over the ground. This is some of the most fun ds'ing I have done because of the lowness, but since I've moved more into mouldies I've lost the nerve to go so low as Ive had a lot of crashes there. A gyro would be perfect for these sites, but having said that, I feel confident I've done my 'apprenticeship' now and am good enough to use gyros if I want.
I used to ride mountain bikes a lot and learned on a hard tail (no rear suspension) All my mates had dual suspension and were faster, so I got one of them. I was immediately faster and less tired, but when I went bact to riding a hardtail I couldn't ride it to save myself and now can only ride a dual suspension because my style is so lazy. This is the kind of thing I'm wary of with taking on a gyro set up.
But then again, in learnig how to Ds I went through a whole lot of planes and maybe a gyro would have saved some of them. So in the end I guess Im sitting on the fence after all!
I think you and Roger and the other gyro guys are real pioneers and inevitably like any new/ better technlogy everyone will be using them some day.
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Old Feb 06, 2012, 04:46 PM
More like crunchman....
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For good order's sake, the Futaba 352 will work with elevons (hence it's installation in an M60) but only because it has a dedicated switch which engages an integrated mixer.
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Old Feb 06, 2012, 04:57 PM
More like crunchman....
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I think your original thinking is healthy, Josh.

Don't learn to drive with an automatic.

It's always important to build & set a plane up properly, whether gyro'd or not, so I wouldn't recommend anyone learning to fly with one.
It's also a complexity a learner could do without.

Why not give it a go?
Roger has achieved much with inexpensive gyros.
No doubt he's had loads of fun for a fraction of the cost of one crashed mouldie.
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Old Feb 06, 2012, 05:36 PM
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ian,

What is HH mode?
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Old Feb 06, 2012, 06:01 PM
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Short answer:
HH = Heading hold, so as to distinguish it from pure rate mode.

Long answer:
A rate mode gyro only applies a correction in response to the instantaneous
change in rate of rotation away from the desired change in rotation rate (stick input).
If the stick is centered then the desired rotation rate is zero. When a gust knocks
the aircraft off axis by say, a rate of 30 degrees per second, the rate mode gyro moves
the control surfaces 20 degrees to compensate, until the rotation stops. If the
gust knocks the plane off axis by 60 degrees per second, then rate mode responds
by moving the control surfaces 40 degrees to compensate, and so forth. It's a
pure action/reaction response. It pushes back only while it's being pushed, but
stop pushing, it stops reacting. Rate mode gyros are typically tuned to overcompensate
a bit, in an attempt to return the aircraft to roughly the same orientation it started, but
there's no guarantee of that. On fixed wing aircraft, the effective
response increases with airspeed because the rate mode gyro always responds with
the same reaction to while the same control surface movement has a greater effect
at higher airspeeds and it can overcompensate so far that it forces
a large rotation in the opposite direction, and then has to compensate for that,
but again overcompensates.. etc. resulting in "Speed wobble".

A HH gyro reacts in response to instantaneous rate of rotation away from
desired but also continuously integrates the deviation from desired rotation rate over
time, and applies an opposing correction in proportion to that accumulated deviation.
When tuned correctly, the two responses added together and push the aircraft back
to exactly it's original orientation. Because it is keeping track of accumulated
deviation this has a side effect of increasing the magnitude of the reaction when it's
far from original orientation, and decreasing the response when it's close to original
orientation, and quickly damping the response down so that it doesn't speed wobble.

In the following video I was demonstrating the difference between two different
controllers on my tricopter, but it happens that one controller uses HH mode
and the other rate mode. The yaw rate of a tricopter is controlled by the tilt angle of
the tail rotor. Whenever it is pushed off original orientation, the tail rotor
tilts in the opposite direction to try to pull it back. In HH mode, it will keep trying
until it succeeds. In rate mode, it tries only while I'm moving it, but gives up
when I let go. In the air, the rate mode reaction may be plenty to return it to
original orientation.
FY30A "3D" mode versus KK Tricopter v2.3 firmware (0 min 46 sec)


Mathematical answer:
A rate mode gyro is just a P-term reaction to error in a PID control loop.
A HH mode gyro is PI or PID reaction to errors in a PID control loop.
http://en.wikipedia.org/wiki/PID_controller

ian
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