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Old Dec 02, 2012, 08:24 AM
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Gyro use in XC competition - Pro or Con ?

Since I started the thread on the 2013 NATS XC event, I've received a couple of off line responses regarding my position that "gyros are allowed".

I've flow XC with and without a rudder gyro, and felt that there wasn't a particular advantage to having one as long a you can see the plane. (My initial gyro use was prompted by the tree tunnel on the old NATS XC course).

FAI rule section 4C, paragraph 1.1 states "For the whole flight, a radio-controlled model aircraft shall be in the direct control of the pilot, via a transmitter, and in the pilot's sight other than for momentary periods." My interpretation of that rule says no gyros in FAI competition, but I don't know if that is the actual practice. No problem, I propose the 2013 NATS XC event allows gyro use as a rule deviation.

Now my attention is drawn to the Powerbox iGyro. This nifty little device combines a 3-axis gyro with a GPS receiver and additional logic to provide additional stabilization. It sounds cool (if it works), and might have saved more than a few XC ships that inadvertantly dove past 'terminal velocity'.

The questions stands - "Should gryo use be allowed in (non-FAI) XC competition? If a gyro unit includes a GPS is it still just a gyro?

What do you think?
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Last edited by dbeach; Dec 02, 2012 at 02:35 PM. Reason: Typo in title
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Old Dec 02, 2012, 10:02 AM
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Hi David

My opinion is that gyros should not be allowed in XC competitions. I believe the general rule should be the pilot must be in direct control of all control surfaces. When using a gyro you would be violating this rule.

However, if you are going to allow gyros, I think the i-gyro should also be allowed. My understanding of the Powerbox i-Gyro is it is a 3 axis gyro that uses gps to calculate groundspeed. With the speed information the unit automatically adjusts the gyro gain to the optimum setting. When flying slow it will increase the gain and when flying fast it will decrease the gain. It is nothing more than a 3 axis gyro with automatic gain adjustment.

Regarding saving a glider from a terminal velocity dive, I do not think the gps in the iGyro would do anything to help in that case. The gyro itself might help prevent the dive in the first place, but once the glider is in a dive the gps will not control the elevator to limit the speed of the glider.

John Ellias
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Old Dec 02, 2012, 11:34 AM
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John - I read some more about the iGyro and I agree with you. All it apparently does is use the GPS speed information to adjust gain. It would not seem to help in a hands off dive situation.
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Old Dec 02, 2012, 11:34 AM
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John, you are only partially correct, an iGyro also can act as a heading gyro too. If you read more, one of it's functions is that if center your sticks, it holds that heading from that point on till more inpout is added. It can hold a pattern/warbird type aircraft in knife edge without any input once the aircraft has established the attitude. Just think of that from the moment you have topped out of a thermal, establish a heading, and then you turn it loose, no input needed.

I think that a single axis, non adjustable gain gyro on the rudder and elevator is no big deal, but an iGyro is another deal, it verges on being an autopilot (an maybe is an autopilot). JMHO

Marc
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Old Dec 02, 2012, 01:38 PM
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Marc

Heading hold gyros have been around for a while, but I guess the iGyro now provides this feature for all three axes. Many gyros have an adjustable gain feature that can be utilized from the transmitter. The gyro I used was many years ago and I'm sure they have gotten better but I still have my doubts how effective gyros would be for trying to keep a glider on course for long distances. My limited experience with gyros is they seem to drift after a period of time. They work well for power applications but they may have a hard time with the extended distances we need for XC.

In any case, your point is well taken and it highlights the pitfalls of allowing any technology that removes the pilot from direct control. If you allow gyro's, where do you draw the line? One axis, two axis, three axis? How about in-flight adjustable gain? how about automatic gain adjustment (like the i-gyro)?

John
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Old Dec 02, 2012, 01:52 PM
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Totally concur John, it is tough to draw a distinct line. Gyros are a very cool tool, can help with pilot load, and I am guesing with some things like DS'ing can add some safety too. I am not sure that is our issue here in XC, but I have no doubt it would be fun to have one on the ship. The only question, does it step across that line about who is flying the ship at times? I am not sure...

Marc
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Old Dec 02, 2012, 02:04 PM
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For whatever it's worth a good HH gyro doesn't need its gain adjusted for changing airspeeds.
I've flown a 60" DS plane from launch to 279mph without having to touch the gain once, using
an ACT Fuzzy Pro airplane gyro in HH mode. Rate gyros do have to change gain
with higher speeds, and they tend to fight the pilot a bit as the speeds go up, requiring
higher control rates.

Anyway, that aside, gyros by themselves won't keep a plane out of a terminal dive. In fact
if the plane pitches up, stalls, rotates around the yaw axis (stall turn) and ends up
point downward at the ground, the gyro can lock it in this attitude, where otherwise
it might have just porpoised or looped a couple times. If you have a plane that is naturally
roll stable and self leveling (bunch of dihedral), a gyro on roll axis will override that,
and can can lock it into a high bank angle, causing plane to yaw toward the ground
and put it into a terminal dive.

If this is really a safety thing, then what you want is an IMU based unit rather than just gyros.
The EagleTree Guardian for instance has a "2D" mode which will level the aircraft
automatically. It's one of the few levelers that works with pre-mixed dual aileron channels.

ian
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Old Dec 04, 2012, 08:08 PM
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I vote No

Quote:
Originally Posted by dbeach View Post

........The questions stands - "Should gryo use be allowed in (non-FAI) XC competition?.....
Thanks David for helping to bring XC Soaring to the Nats to us for a second year in a row.
I agree that AMA allows a provision for deviating from any rule in a contest class if it's announced before hand, which you've done. However let's look at those that oppose the usage of gyros :

The FAI f3h rules don't allow it.

AMA's 446 XC Soaring class used to be defined as "See FAI F3h" but now just states "For FAI events, see the FAI sporting code." ,thus also would not allow it.

AMA's safety code which state's "The pilot of an RC aircraft shall : Maintain control over the entire flight, ...." (Granted this is vague but could easily be interpreted as not allowing a gyro to control flight surfaces. )

Lastly this question was addressed in the recent past with John's "Allowable Technology" thread. By my count there were 12 people opposed to electronic stabilization and 2 for it with several not very clear on their vote.

If your intent is to reduce the number of lost gliders due to a lack of inherent stability then make it stable. To improve pitch stability, move your CG forward and or build a bigger stab. If you need to improve roll stability then make a new wing joiner for increased dihedral or add polyhedral wingtip extensions for increased effective dihedral.

Mike
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Old Dec 05, 2012, 07:36 AM
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Quote:
Originally Posted by ThermalSeeker View Post

... this question was addressed in the recent past with John's "Allowable Technology" thread. By my count there were 12 people opposed to electronic stabilization and 2 for it with several not very clear on their vote.

Mike
Mike,

Thanks for your opinion, and the reminder regarding last year's thread. I just went back and re-read it.

I agree, the consensus among current XC fliers is clear. My original position regarding allowing the use of gyros was based on my personal belief that it might encourage new participants. However, I don't want to do that at the expense of discouraging current fliers.

So, based on all the feedback I've gotten - gyros (and/or any other device that is contrary to the FAI rule regarding "direct control of the flier") will NOT be allowed in the 2013 NATS XC event. Time to update that thread...

David
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Old Jan 26, 2013, 05:45 PM
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I guess someone will need to tell all the heli pilots flying FAI events that they'll need to remove their gyros because they are not in direct control of their helicopters.

If you move your transmitter sticks and the appropriate control surface moves, then you are in direct control of that surface. That a gyro has additional influence doesn't negate a pilots control of the control surfaces or the aircraft. The gyro simply add a degree of artificial stability.

Now if you want to disallow full on autopilots that will fly the sailplane to all the designated turn points without any required pilot input, that is another matter, and one that might require a separate class.
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Old Jan 26, 2013, 07:46 PM
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There is "In the loop" and "On the loop".

Heli guys are IN the loop.

With a full-on autopilot, the modeler would be considered ON the loop.
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Old Jan 26, 2013, 09:46 PM
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Who here is advocating for full on AP?
Last I checked the thread title started with "Gyro use... ".
There are many airplane gyros in which the pilot is "in the loop" 100% of the time.
The iGyro is just a HH gyro with the added trick of adjusting the gains based on
ground speed (which as I pointed out above, is really not necessary).

ian
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Old Jan 27, 2013, 12:19 PM
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Quote:
Originally Posted by tkallev View Post
There is "In the loop" and "On the loop".

Heli guys are IN the loop.

With a full-on autopilot, the modeler would be considered ON the loop.
True, but we're talking gyros here. AP's would be another set of rules, if required. But if someone has an issue with gyros, then we should also ban computer radios with mixing capabilities since "control surfaces, other than what the pilot directly commanded, would move".

For the record, I don't have any problem with gyros in sailplanes, especially since heli's and other competition aircraft have already set the precedence. I also don't have a problem with advanced gyro/GPS systems (autopilots), but I would agree that they might need to be in an "open or unlimited" class.
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Old Jan 27, 2013, 04:18 PM
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I'm pretty much with you, Ben, but there is one gotcha that should be noted:

AMA prohibits any autonomous flight by a model, thus the in/on the loop reference ... Originally there was a single prohibition, it has since become much less straightforward:

http://www.modelaircraft.org/files/560.pdf
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Old Jan 27, 2013, 06:01 PM
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Ian, the iGyro does not only HH, but in HH mode, yo basically set the heading and attitude, and she will hold it all. Now, that is not "an autopilot" by rights, but for XC it makes the task insurmountably easier than what it is without.

Marc
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