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Old 01-07-2022, 08:33 AM
jraycut is offline
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Whelp! Looks like Zeeb stood corrected.

Glad everything worked out! Now - back to Waynes World, lol….JETS!!
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Old 01-07-2022, 08:48 AM
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Quote:
Originally Posted by jraycut View Post
Whelp! Looks like Zeeb stood corrected.

Glad everything worked out! Now - back to Waynes World, lol….JETS!!
Yes, Joe….. I spoke with Brandon last night for the very first time, and was advised that the incident was with another event. It had nothing to do with myself OR the Jet Nationals. I do notice that the offending posts were removed, without anything said. It IS so unfortunate that an apology is not forthcoming, but such is life!

Let us talk about Gyros next.
This is one of the most misunderstood technology allowed in F3S competition. I will gather up my 4 years of experience and also what I’ve learned from other avid competitors.
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Old 01-07-2022, 10:27 AM
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I'd like to learn more about gyros. I just installed the Cortex Pro in my Rebel Max. Have only flown the Max three times with it and not sure what to expect.

Let us talk about Gyros next.
This is one of the most misunderstood technology allowed in F3S competition. I will gather up my 4 years of experience and also what Iíve learned from other avid competitors.[/QUOTE]
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Old 01-07-2022, 10:55 AM
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Ideally, if the gyro and the jet are well set up you wont notice it in calm conditions, what you will notice is enhanced stability in the wind, no issues landing cross wind, that sort of thing.
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Old 01-07-2022, 02:39 PM
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Quote:
Originally Posted by BarracudaHockey View Post
Ideally, if the gyro and the jet are well set up you wont notice it in calm conditions, what you will notice is enhanced stability in the wind, no issues landing cross wind, that sort of thing.
That's good information, I haven't flown it on a very windy day since installing the gyros. Just have to go and fly it on a windy day

Thanks
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Old 01-07-2022, 03:18 PM
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Quick primer on gain. There's 2 types that affect the overall system. Mechanical and electronic gain.

Electronic gain is simple enough, the higher the gain the more the servo output for a given sensor movement. So in simple terms (its actually algorithmic but keeping it basic). If you have the gain set at 20 and you move the gyro 10 degrees it deflects the servo arm 10 degrees. If you double the gain you get twice as much correction for the same gyro movement.

If it were only that simple, now you throw in mechanical gain. All these factors play into the total gain of the system but some have more effect than others.

Servo arm length: If the servo output moves 10 degrees and you have a short arm you get a small surface movement, if you have a long arm you get more movement.

Servo speed: Similar as above but it gets there faster

Now the two big ones
Control surface size and airspeed.

Big control surfaces (think 3d planes) have many times the surface area of our jets, the bigger the control surface the more the effect of moving that surface a given amount.

Airspeed: the higher the airspeed the more effective the control surface is at a given deflection.

All these factors have an effect of the total system gain of our airframe.

Too little gain and the gyro is ineffective. Too much gain and corrects and reacts so quickly to the correction that it corrects the other way, in helis we see this as "tail wag" but in aircraft too much gain coupled with too much speed and we can get serious oscillation of one or more of the control axis which as you can guess is a bad thing.

Since we can't alter control surface size, servo speed, or servo arm length in flight we can accept them as they are.

What we can and do alter is electronic gain, airspeed and control deflection.

We want the most electronic gain we can get without getting the over correction and oscillation.

If you're thinking this through, then you can see, especially in our case where the speed envelope is so wide, that once the gain is optimized at high speed it could be inadequate at landing speed. It's a compromise but usually works pretty well, the Cortex is a great gyro and once you get the max gain you can run at full airspeed it usually works well for all flight regimes.

There's a couple ways to optimize gyro gain.

The Cortex doesn't have a speed input but an iGyro used with a Mercury or Pioneer, SRS etc can have an optional gps module that lowers the gain as speed is increased. You can also do what I do, bump the gain with a mix that gives 10 points or so more with full flaps or landing gear down.

Something the Cortex and other gyros do allow is setting the gain per-axis where you can find the speed where the ailerons shake and back that down till you get some elevator oscillation and then find the max you can run on each axis.

Note that this takes some flight testing and if you get oscillation you can not only back off the throttle but pull up a bit to bleed airspeed and it will stop. Putting the gain on a knob allows you to "sneak up" on the best setting either with a helper or if you're comfortable tinkering then you can set it to a switch with one position OFF in case the gyro pops loose.

Hope this helps.
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Old 01-07-2022, 04:02 PM
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THAT'S about as good information as we can get!!Thanks Andy for such a valuable input. It is really appreciated.
W
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Old 01-07-2022, 06:07 PM
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I have flown Powerbox with iGyro and liked it. Currently, I run Cortex Pro's in my jets. No particular reason either. It's just the setup I've used lately as both systems are both very good and comparable.

Just some very basic Cortex info/personal tips:

For someone looking to use a Cortex in a jet, many pilots will simply start by copying bank 1 (RATE/NORMAL) to bank 2 (HOLD) and eliminate the HOLD mode that is defaulted in bank 2 (unless you run thrust vectoring and do hovering with your jet, then you may want to keep HOLD in Bank 2). Bank 1 can be used for T/O and Landing settings and Bank 2 can be used for high speed/normal flight. Program a higher gain/sensitivity for bank 1 and lower for bank 2. That kind of acts like a very rudimentary speed compensation factor for the Cortex brand setup. While it is not speed compensated linearly, like a GPS equipped iGyro setup with Powerbox, it works very well in the aerobatic arena where you'd usually be flying a certain speed/cadence envelope during level flight anyways. I've set up a 3-position switch for the gyro functions for flying sequences (Off, Bank 1, Bank 2) in order to capture the slow speed abilities of bank 1 during slower parts of a figure, and then swap to bank 2 during the rest of it. That setup may require a switch flip or two, during a certain figure, but I've also eliminated dual rate switch flips (which is commonly used in gyro-less models in aerobatics such as IMAC) by setting up the priority & lock-in of the stick movements within the designated bank. I can also then fly on high rates the entire flight, and the gyro will coordinate a certain expo feel into those settings I've put in. Keep in mind, you can also have a dual rate switch, but remember stick priority/lock-in within the gyro will take care of needing much if any expo (and always initially program the gyro using the HIGHEST rates). Don't forget, once you turn off the gyro, it would be advised to have that particular switch position activate a traditional expo setting. I once did a maiden on a jet that I forgot to set expo up on the "gyro off" position and it made for a rather exciting/underwear changing type of flight. Also, the flap switch will run bank 1 automatically during takeoff and landing regardless of the other 3 position switch I had mentioned. That is easily accomplished with simple mix.

Some people get confused on the difference in Priority and Lock-in while setting up a Cortex.

Priority is how much stick movement is required to fully override the gyro stabilization. The lower the number here, allows the gyro to continue to stabilize the further out from center the stick moves.

Lock-in is how fast the gyro stabilization reactivates when returning the stick to center. The higher the number here, allows the gyro to start stabilizing the surface sooner as you return the stick to center.

Not sure if any of this helps, but just some info into my views.
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Old 01-07-2022, 08:02 PM
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BH and RC, that is for sure good information and a fair amount to understand. I have the gyros on a switch so I can turn if off, sneaking up on the gain sounds like what I need to do, among other programming. I have plenty of time though as we don't have a F3S event until March. I'll keep reading this and any other information as well.
Thanks again,
Dave
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Old 01-07-2022, 08:27 PM
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Gotta love all the information you guys are sharing here on FG....not into this segment of RC yet, but if/when I am it's nice to know resources like this exist.
Bill
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Old 01-07-2022, 11:25 PM
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Thanks for your input Adam! The above information from both Andy and Adam is what this thread is about. Helping other pilots to decipher and utilize not readily available info goes a far way in promoting jet flying in general, but also turns the lights on for pilots who want to delve deeper into setting up their aircraft for competition.

The adaptation of the gyro technology into our competition is accepted and allowed by the FAI in the rule book. This question has been asked many times over whether or not a gyro can be used in F3S competition.

Coming from a Scale Aerobatics background where a gyro is not allowed, and never having been exposed to the technology, I was “in the dark” and very scared to use it at first. Matt Balazs steered me through my initiation into this new world and I’ve NEVER looked back. What I’ve ALSO learned, is, contrary to popular belief, a gyro DOES NOT fly a plane for you!

We now have over 143,000 hits on this thread. That must say something for the exposure it gives!
Wayne
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Old Today, 04:49 PM
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I was finally able to complete the 2021 Jet Nationals report with photos and pilot data.
https://www.jetaerobatics.org/2021-nats.html


Hope to see some more of you guys there later this year.
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