Didier

This phenomenal I experienced twice now.
The first one on a Wizard S with a K70 and Jeti12A. In the end I made a soft Balsa box with foam around. This was the fix.

Last week with my new Viper and K102 and Cortex Pro I had the same issue! I was a bit disappointed as the Cortex have such a good reputation concerning this issue. Anyway, build the same Balsa box with foam. No time to test it yet.

Both planes are very very light build and I guess the airframe amplifies the sound. With a more solid build airframe/fuselage this phenomenal seems to be less. Just a theory from my side.

HarryC

My Feedback: (1)

Yes they do David. Do you remember me nearly losing my F-86 Sabre at Wroughton with Weatronic, it was Weatronic themselves that said it was acoustic interference after they examined the data logs I sent them. I went on to prove it on the ground the next time out at Wroughton. Weatronic staff told me of their own models suffering acoustic interference with their gyros. When I posted about it on the rcu wea thread, other Wea users came forward with their experience of getting the interference.
In the Powerbox forum you can find at least one thread where Richard is dealing with a customer getting acoustic interference on an igyro. It is very very rare, but rare is not the same thing as zero.

Halcyon66

Pretty amazing David that you NEVER seem to have a problem with anything?

Regards,

Dansy

My Feedback: (53)

I’m surprised that you had that happen with the cortex pro….maybe it’s not mounted on a 100% solid platform? I always used the thing foam that come with them..and got extra in case to remount and nothing else, I also make sure the cable can move…freely ( a little)

I it’s everything is possible but never experienced in any jets….or seen one doing that….

Didier

Yes, I was surprised to. I have mounted the cortex to the supplied radioplate made of a carbon sandwich construction with a core of green foam. I did not use the thick double side foam as this is for gassers (to dampen vibration, not noise) and the thin foam seems to be for jets and electric powered planes like the manual explained. Next time I will try the double side thick foam first. As you can see in the picture the wiring hangs “loose”.

I talked with an expert and this “can” happen with all MEMS equipped gyro’s. I think this phenomenal happens more often then we know. Most people don’t pay much attention during the first runs with there jets on ground. Most of the times gyro’s are off in the beginning anyway.

David Gladwin

Please , HARRY, reread what I wrote.

I said, not ALL gyros have the problem My experience, real experience, with many electronic gyros in many models is that I personally have had no problems, not one with gyros.

I am NOT saying there have been no problems but I have had none and you have seen my Hawks, BobCats etc flying for many years with them.

I can relate ONLY to my personal experience with electronic gyros which is quite extensive.

My gyros:
Fuzzy Pro.
JR piezo x2.
Weatronic Gizmo , gyro 3, x 4 Including almost 300 flights on two AW Hawks over 14 years, still flying, still serviceable. Plus one in a SkyGate Hawk and one in a Mig 29.
Weatronic Micro 12, 3 gyros, x 4 800 BobCat flights over almost 20 years , still flying, still serviceable.
Power box gyro I sat, 3 in use,. ( In Reaction, Sabre, Sea Fury.) 3 waiting to be installed.
NONE have given me ANY issues, and so I cannot agree that ALL gyros have the problem.
I have no doubt that some gyros have given problems, why its random I don't know, but NONE of mine have, even though I am using the same make of gyro which have given problems.

PS Another gyro which gave excellent results was the Weatronics 8 ch gyro 1 which greatly smoothed my Savex L39 for many trouble free flight, til its midair !

HarryC

My Feedback: (1)

David, every brand of gyro and every individual gyro that they make is at risk from acoustic interference if the noise is there. It is baked into the design of MEMS gyros. Some brands are better at filtering it out in software than others. You could take one of your existing gyros, put it in another model which is generating the right noise for that gyro and you will get the interference. One in X number of gyro/engine/model combinations will get it, thankfully X is a fairly big number. Therefore saying that you have not had it adds no information!

David Gladwin

Then Harry, we must agree to disagree ! I DID give you information based on experience.
Perhaps I have been lucky, very lucky , and not encountered the frequency band which is problematic on some gyros.
However, my installations vary from a low revving engine, Olympus ( plus a vibrating Moki) through several others including a twin JetCat 140s, to the hjghest revving, Xicoy X 45. Fully ducted, internal unducted and external. Harmonics, beat frequency, etc., , who knows ?
I will leave it at that and continue to enjoy my trouble free gyros !

Have just killed a few minutes researching the effect of vibration on MEMS gyroscopes which is the type we are now all using.

What has been found is that different frequencies of physical vibration affect different mems to varying degrees, generally 20 to 30 Khz seem to be the culprits in one paper on the subject.The maths are way above my payscale !

I always mount my gyros on a relatively soft mounts ,foam rubber for gyros in receivers, foam tape on discrete sensors, it does not seem to reduce their sensitivity. Maybe, just maybe, that is why I have never had a problem, despite a very wide variety of environments. But the bottom line is never a problem !

jvaliensi

My Feedback: (1)

I am getting nasty glitches on the rudder from the gyro. My set up is Rebel Hot with Cortex Pro and Kingtech K70G4. I've used the Cortex Pro in several jets without any issues. I've even had another Rebel Hot with the Cortex Pro with no issues, but it had an X90 in it. I've used the K70G4 in two other aircraft with the Cortex Pro with good success.
I tried covering the gyro with Kaisen foam and it didn't help. My equipment tray is made from 3mm plywood and appears to be stiff enough. There isn't room to mount a HushBox. I wonder if the Kaisen foam is not dense enough to block the noise.
Is this problem unique to certain turbines? Why does it only happen to the rudder channel?

BarracudaHockey

My Feedback: (11)

Certain "installations"

Could be the airframe, could be the motor, its just that combination and its picking up noise.

Moerig

Mems Gyros need really good software for a particular application. Jets are some of the most challenging I would think. Source of most noise would be:
1. Intake and exhaust turbulences.
2. Acoustical combustion noise (low frequency rumble, often worse with poor combustor design)
3. All combination of above and resonance of same can be quite random.
Of these its the lower frequencies that is a problem, since the Gyro could have difficulty in discerning this from valid movements of the airframe.
So damping the noise with foam is good, but it should not allow gyros to be able to sympathetically vibrate. So it has also has to be held firmly with not too much 'springy' movement.
Its just physics.

CARS II

My Feedback: (7)

I’m just going to throw this here.

How about reducing the sensitivity of the rudder, from what I’ve experienced on all my airplanes with gyros is tthat the rudder is the first control surface to be affected by been too sensitive.

jvaliensi

My Feedback: (1)

I'm an engineer, so basically I'm lazy and always try the easy stuff 1st. I tried reducing the rudder gain - no joy, tried changing to a lower servo rate - 166Hz - no joy. Turn the gyro off the rudder quits jumping. I ended up turning the rudder gain to zero so I could fly. But I'd really like to bug this out, the airplane turns different with the gyro on two channels only.

CARS II

My Feedback: (7)

This may sound wild, how about changing the servo, same brand, if it’s still doing the same then a servo of a different brand.

CARS II

My Feedback: (7)

I’ve also experienced vibrations during the vibration test that I have done on each of my airplanes, it’s done with the gyro gain at 100%, I can see the most vibrations at about 80% to 100% and like David G. Never enough to not be able to fly the jets or prop planes.

I hope you can fix this, good luck and let us know what was the fix.

BarracudaHockey

My Feedback: (11)

To be clear, mounting isn't your problem, acoustic noise is. A hushbox is your answer or possibly relocating the sensor.

FlyJ

Does this happen in the air or only on the ground?

I assume you have the gyro mounted on the deck. You should try to relocate it to be on the floor of the jet. Right on the center seam where it’s super rigid. I had this problem and it was solved once I moved the gyro off that deck.

CARS II

My Feedback: (7)

jvaliensi

My Feedback: (1)

My issue is defiantly noticed in flight. Flying down the runway I noticed the airplane doing a yaw-wiggle. I can reduce the gain in flight, which didn't make this go away. When I was turning from downwind to base the rudder went nuts and it felt like it would not let me complete turn. Fortunately this only lasted a couple of seconds and I landed safely. That got my attention and I started to look in to this.
I think I have other planes with the yaw-wiggle. For the Matrix I reduced the rudder gain and it went away. Now that I know about this I notice it more.
My 1st Rebel Hot never had an issue. As noted above, the gyro was mounted lower on the deck. That may be the best spot for the gyro.
The Kingtech has a deeper, louder sound than Xicoy's do. I'm thinking this is why this is showing up.

TJPro351

My Feedback: (8)

I have the same problem on a PC-21 using a turbo K60. I see it in flight and on the ground. I am using serial with a wire going to port A and B and one for power. On my Renegade, I have the gyro set up using the supplied "jumper" cables and never seen this problem. I have had several different type of Jets using the Cortex and 95% of the time, use the jumper cables. You can try that to see if it makes a difference....just a thought

Moerig

Real men don't use gyros, ask any helicopter guy before the first gyros were invented.

jvaliensi

My Feedback: (1)

I guess its possible that the serial bus is picking up interference and causing the issue. But, I would expect all servos affected. Shielding of the bus cable may eliminate this.

mongo

My Feedback: (15)

real men fly real aircraft,
toy men fly toy aircraft

FlyJ

This is extremely unlikely. Vibration to cause a specific packet to get lost in the bus? And for it to be the same packet continuously with no other lost information?

This is almost certainly mechanical. The top deck of the rebel is a drum/tuning fork which is just vibrating at some mid frequency (~1300hz). I'm sure the gyro has some low pass filter to ignore frequencies over a certain point which helps tune out most turbine initiated noise at the top of the spectrum, but there can't be a high pass filter since the perturbations detected by the airplane are generally very low and high amplitude (wind oscillations and such). I bet there's a certain point in the throttle curve where the engine hits a small resonance and just transmits it through the fuse, which is being seen here. I'd be curious to strap an accelerometer to the turbine and find that point, that could tell you where the gyro filter ends. Unfortunately we can't setup our own filters on the gyro to prevent these things so you're left with mounting solutions only.