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PostPosted: Wed 18. Sep 2024 14:31:41 
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Joined: Wed 10. May 2023 9:36:53
Posts: 37
Location: The Netherlands
Driveline651 wrote:
[quote=“senaka”]
200 on the y axis, yikes ! you must be able to hear that vibration not only feel it :o . I would get that sorted soon as it will wear out moving parts.


The helicopter exhibits no signs of vibration, seems to fly very smoothly. Just like the 550x that has similar numbers.
I would be interested to hear some feedback of what your helicopters numbers are for comparison. I’m still waiting to get a response from ZEX as to what he thinks.


Mine ranges from 30-45 on all.


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PostPosted: Wed 18. Sep 2024 14:34:49 
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Joined: Sat 13. Jan 2024 18:40:38
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Zex,
I have attached pictures from in flight hover of the tb40 .
One is the logger and shows a relatively low vibration around 29% in magnitude

The other is the Y axis of the in flight spectrum analyzer and it shows a very high vibration level of 277

Both of these pictures are from the same flight . Stable hover in idle 2

Please advise


Attachments:
File comment: Tb40 in flight idle 2
Y axis spectrum analyzer

IMG_3466.jpeg
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File comment: TB40 in flight hover idle2
IMG_3467.jpeg
IMG_3467.jpeg [ 2.04 MiB | Viewed 182 times ]
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PostPosted: Wed 18. Sep 2024 20:37:10 
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Joined: Mon 29. Apr 2013 16:06:44
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Thank you.
I can say only that I highly do not recommend to fly with this model now.
The vibration level is insane. Basically the level is so high that with the most other gyros it will be not possible to even lift off (even with half the level).
There are strong resonant vibrations that must be resolved.
The problem is tail mechanics.

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PostPosted: Thu 19. Sep 2024 1:11:24 
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ZeXx86 wrote:
Thank you.
I can say only that I highly do not recommend to fly with this model now.
The vibration level is insane. Basically the level is so high that with the most other gyros it will be not possible to even lift off (even with half the level).
There are strong resonant vibrations that must be resolved.
The problem is tail mechanics.


Zex,
Thank you ,
Can you help me understand how it’s only 29% vibration on the logger , but so high on the Y axis at the same time ?
Also on the bench the vibration is less than half , around 110 on the y axis .

Also , could you share what a normal level would be both on the Y axis and as a percentage on the data logger ?

In the mean time I will continue to dig and see if I have missed anything.
Thanks!


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PostPosted: Thu 19. Sep 2024 15:20:32 
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Joined: Sat 13. Jan 2024 18:40:38
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For comparison, here are inflight graphs of my Align 550X with spirit GT . It flys very smoothly, nothing bent , everything spins like butter , never crashed .
Was on beastx until this spring . Never any issue with either FBL , strictly for comparison.
The numbers again look good on the logger but High on the Y axis .
Not say things couldn’t be made better , but I also don’t want to go down a rabbit hole with the TB 40 , end up replacing everything with new even though it all checks out fine , and end up with the same result .
Does anybody else have similar graphs of their good flying helicopter to share for comparison?


Attachments:
File comment: Align 550x idle 2 stable mover for comparison
IMG_3470.jpeg
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File comment: Align 550x idle 2 , stable hover for comparison 29%
IMG_3471.jpeg
IMG_3471.jpeg [ 1.97 MiB | Viewed 152 times ]
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PostPosted: Sat 21. Sep 2024 7:12:42 
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Hello,

thank you for sharing the plots.
Difference between telemetry vibration level and Spectrum Analysis is because both are measuring in a different way, using different algorithm.
When vibrations are of high frequency then the telemetry value will be much lower in comparison to Spectrum Analysis tool.

Unfortunately I have to say that both helicopters are far from good. Because Spirit GT has so good sensors, it just works.
But for Rescue precision it could be different matter, since it require very precise measurement during whole flight.
Unfortunately vibration level is roughly 6x higher than what is considered to be normal. This is HUGE difference.

However from your TB40 they are of different kind - you can see they are resonant, because there are a lot of spikes at harmonic frequencies. This will disturb all motion sensors the most from any vibrations. So not only they are very, very high, they are also resonant. In other words, even gasser models will not produce so big vibrations.

Some electric helicopters have Total Vibration Level not exceeding even just 20%. But normal level is around 50%, while all spikes should not exceed 100% of the Amplitude (height of the plot area).
If you can lower it at least to 100% it would be much safer also for helicopter mechanics itself, because resonant vibrations are able to unscrew all your screws itself. There is distinctive noise produced when they are appear. Maybe you have not noticed it because they are there from the beginning. Almost always problem is developing at the tail mechanics, because this place is relatively flexible and when something is loose it could start to happen.

So first from all I recommend to carefully verify Tail Mechanics. Some models has this flaw from the beginning unfortunately but it is not common for Align models. But for example old Protos 500 were almost all problematic and for this reason units such as Microbeast were often unusable there. But clearly the problem was at the model, but it was not easy to resolve because of the design and imprecision between parts.

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PostPosted: Sat 21. Sep 2024 15:31:29 
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ZeXx86 wrote:

So first from all I recommend to carefully verify Tail Mechanics. Some models has this flaw from the beginning unfortunately but it is not common for Align models. But for example old Protos 500 were almost all problematic and for this reason units such as Microbeast were often unusable there. But clearly the problem was at the model, but it was not easy to resolve because of the design and imprecision between parts.


Thank you for taking the time for such a thorough response . I appreciate your input and knowledge.
I am struggling to understand how two different helicopters, with two different spirit GT units. That both seem to be vibration free in flight and fly very well can have such high vibration levels shown only on the y axis while all others are within normal ranges.

I guess it’s possible the 550x has some undiscovered issue , I doubt it but will go through it to make sure .
Unfortunately I have spent many hours on the TB 40 at this point and have come up with nothing. I have dial indicated the main shaft , tail shaft , both feathering shafts , all but the main shaft had absolutely zero run out , with the main shaft having a half a thousandth or .0005 “ which I think is acceptable”. But I happen to have another brand new tb40 kit so I have also systematically swapped out the main shaft , complete tail assembly with no improvements in vibration on the y axis .
I have checked every bearing for roughness or looseness all feel perfectly fine . I have tried many different belt tensions with no change in vibrations, I have clearanced the belt tensioner and idle pulley bracket as the belt was slightly contacting it , no help.
Keep in mind while bench testing the vibration levels were almost zero with only the main grips and tail blades and grips removed, and around 50 with them installed (y axis ) . And raise to about 100-115 with the tail blades installed and spinning with zero pitch , but show more than double that vibration level in flight. Each tail blade with its bolt and nut are within 0.2 grains or 0.013 grams of each other , and the main blades are balanced perfectly on a beam style blade balancer .
At this point I think I’ve done about as much as I can do .
I did remember you had asked for pictures of how the unit was mounted, so I have added those for you to look at to see if I’m missing something there . But the normal things to check like tight wires , no frame contact , one mounting pad etc are all normal . Maybe it’s possible that the fbl mounting plate is somehow transmitting resonant vibrations, or maybe this is all just typical of this align TB40 . Or maybe the spirit unit is over sensitive on the Y axis especially in flight, but that doesn’t sound like it’s the case as it sounds like other helicopters can get the vibrations down around 50 .
Please take a look at the fbl mounting pictures and provide any feedback.
Thank you .


Attachments:
IMG_3481.jpeg
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IMG_3480.jpeg
IMG_3480.jpeg [ 2.26 MiB | Viewed 109 times ]
File comment: Tb 40
IMG_3479.jpeg
IMG_3479.jpeg [ 1.24 MiB | Viewed 109 times ]
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PostPosted: Sat 21. Sep 2024 16:25:33 
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Joined: Wed 04. Jul 2018 18:03:55
Posts: 179
Just an observation from me but it looks like the channel 3 servo wire is touching the corner of the case....May be its not, but looks close to me...


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PostPosted: Sun 22. Sep 2024 7:43:02 
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Hello,

the problem comes from tail mechanics, where it could be enough one tail grip has some assymetry. Even just small missing washer could cause this.
You will not notice any vivrations of the model in flight, because tail vibrations are at high frequency. You will either not sense them well with a hand. Spirit does not bother even if flying with a bent main shaft or even if one of your main blade is longer by 1cm. But in tail it could be just some play, something that is not fitted in a fully. Tail mechanics can produce resonant vibrations while anything at main shaft cant.

Y axis has always the highest vibrations because of RC helicooter model design. All axes are measured in the same way. Mounting looks good. So I would only disassemble tail and check each, bolt, washer, bearing.

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PostPosted: Sun 22. Sep 2024 8:03:22 
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Joined: Sun 08. Jan 2023 14:32:43
Posts: 286
if you fly with high vibrations you fly well in the same way.
But when you activate automatic functions such as the rescue, the vibrations they make you behave strangely ONLY when the function is active.

In my case helicopter was flying well and if I activated rescue the helicopter leaning at 45%.
Deleted the vibration the problem is gone.
Dismantle helicopter and system the vibration


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