Tail problem

[mkovalcson]

Originally Posted by Puttputt maru

Here is an idea or may be some one had it already but why not make a vibration analyzer unit that could be use on any helicopter with any FBL unit?

Personally I like having vibration logs all the time because it helps me to diagnose issues and see if something is failing.

Like my most recent TDR issues with vibration. I checked the logs when I heard a noise, and the flight logs quickly confirmed that there was an issue to look at. However if I had taken a bit of time to check my previous log files I would have seen that this vibration had been slowly creeping up flight after flight.

I do check my logs on the Banshee when I get home from the airfield, but I've gotten complacent with my TDR because it just goes and goes and goes and I've had it a lot longer.

[Puttputt maru]

Of couse, the unit should have a log capability or better yet telemetry log. I think Jeti should make one.

[Puttputt maru]

By the way how do can you tell from your log result where the vibration is coming from?

[mkovalcson]

Originally Posted by Puttputt maru

By the way how do can you tell from your log result where the vibration is coming from?

Skookum has two types of logs.


1. Flight Log - that's a record of all of your TX inputs to the SK-720 along with BEC voltage, acceleration and overall averaged vibration.


With a flight log you can find things like interactions between servos and vibrations. For example you might see a vibration when your elevator is binding above 95%. Or if you give it a lot of aileron at full collective. Granted those are setup issues that you should find on the bench, but it can give you insite into what is going on. It can also help with a post mortum after a crash to let you know what the heli was doing when it crashed.

2. Vibration Log - I use this mostly on the bench, but sometime in the air.

The vibrations are graphed by frequency and by orientation.



There are three sets of vibration graphs

1. fore/aft
2. up/down
3. left/right

These are plotted vibration G force across the different frequencies.

So you can see vibration at motor frequency, intermediate gear frequency, main gear frequency, tail gear frequency.

Typically Motor is about 10x the headspeed and tail is about 5 times the head speed.

Recently I had an issue with the Pyro 650-103 on my 550SX. The vibrations were all up/down at the speed of the motor at lets say 24,000 rpm, but only when using the governor. It turns out I had a magnetic resonance issue. I adjusted my Jive's timing settings and got rid of this vibration. The motor without governor active was smooth as silk so there were no balancing problems with the can.

Also after recently wrecking my Banshee with what appeared to be light damage I was able to spin up the main drivetrain and verify that all the bearings were still good and the shafts were still all straight. This saved me a complete breakdown and gave me the certainty that I wanted to know it was OK.

[Puttputt maru]

Also after recently wrecking my Banshee with what appeared to be light damage I was able to spin up the main drivetrain and verify that all the bearings were still good and the shafts were still all straight. This saved me a complete breakdown and gave me the certainty that I wanted to know it was OK.

This is very interesting I had not thought of also using vibration log in that fashion. Thanks for taking the time. And I would be on the verge of a breakdown too if I had wrecked my (hypothetical) Banshee Good thing it is not bad

[mkovalcson]

Originally Posted by Puttputt maru

This is very interesting I had not thought of also using vibration log in that fashion. Thanks for taking the time. And I would be on the verge of a breakdown too if I had wrecked my (hypothetical) Banshee Good thing it is not bad

I use it on the other side of a rebuild as well. I have baseline vibration graphs from known good original built with perfect parts. After a rebuild I spin my helis up on the bench to see if I missed anything. If something looks off, I examine the area that doesn't seem up to snuff.

[Mercuriell]

Having a vibration log in 3D must be a huge advantage to an overall value when troubleshooting. Might be worth having a mobile Skookum as a tool to used when having vibe problems

[Puttputt maru]

Originally Posted by Mercuriell

Having a vibration log in 3D must be a huge advantage to an overall value when troubleshooting. Might be worth having a mobile Skookum as a tool to used when having vibe problems

Exactly what I was thinking but why not just make a vibration analysis device on its own. Smaller and more transferrable. Plugged to the Rx and with on/off data recording capability through the TX

[belgoheli]

Originally Posted by Mercuriell

Having a vibration log in 3D must be a huge advantage to an overall value when troubleshooting. Might be worth having a mobile Skookum as a tool to used when having vibe problems

I still miss the point of the 3D. I find the V bar vib log giving plenty enough of info.

All rotary parts of a helicopter can cause vibes in any direction; for instance head dampers are capable of creating wobble on roll but as well as on the nick axis. I guess this applies for all frequencies since we are talking about rotary sources.

To me the only useful values are frequencies no matter which direction they come from

But probably I could be missing something and eager as I am to learn, I d like to know

Thanks

Belgo

[mkovalcson]

Originally Posted by belgoheli

I still miss the point of the 3D. I find the V bar vib log giving plenty enough of info.

All rotary parts of a helicopter can cause vibes in any direction; for instance head dampers are capable of creating wobble on roll but as well as on the nick axis. I guess this applies for all frequencies since we are talking about rotary sources.

To me the only useful values are frequencies no matter which direction they come from

But probably I could be missing something and eager as I am to learn, I d like to know

Thanks

Belgo

motor vibration side to side and fore/aft is typically a mesh issue
motor vibration up/ down is typically bearings or magnetic resonance.

Tail vibration up/down and fore/aft is typically blade balance
Tail vibration left right is typically tail bearing.

You look at the relative sizes of the directional vibrations to see which are the largest.

[belgoheli]

Many thanks Mark,

Very helpful
Perhaps I should consider the Skookum for my new TDS....
However in the absence of a SK I am not able to make a comparison flight wise

Regards

Belgo

[mkovalcson]

Originally Posted by belgoheli

Many thanks Mark,

Very helpful
Perhaps I should consider the Skookum for my new TDS....
However in the absence of a SK I am not able to make a comparison flight wise

Regards

Belgo

Something else of interest. I've always liked how my SK-720's fly, but they are coming out with a new firmware release that they say is night and day better in the next 2-3 weeks. That I am VERY interested in trying out. They are crowing pretty loud about this one and the beta testers are just telling us wait until you try this out. I've not heard this amount of crowing about a firmware release since I started with SK products in 2011. So if it isn't all that, they have really set themselves up for a fall.

This new release has some interesting new features that I've never seen on a FBL controller. I can't find the screen shots of the beta testing screens I should have grabbed them when they were first shown. They were pretty interesting. Past support for UDI, and some other protocols

I think VBar, BD and Skookum are all systems that can be configured to fly well on most helis. However some helis seem to work better naturally with one FBL controller over another. I've heard people struggle to get VBar or BD to work with a specific heli that just doesn't "feel right". I've not personally had that experience with SK, but I'm sure that it is also true for SK.

I won't try to sell you on them. I like them and have been very happy with them, but I don't have a lot of experience with other FBL controllers. I do really like the flight log/vibration log and analysis tools. The new SK-720 BE pinpoint gyros are as vibration immune as gyros go, but the auto-leveling will stop working with heavy vibrations and I've not been able to get my Banshee over 2,100 rpm speed flying without disabling the bailout, or my TDR over 2000 rpm speed flying without disabling the bailout, so if you are looking for a safety net while speed flying the SK is not as robust as the BD bailout.

[Mercuriell]

Originally Posted by Puttputt maru

Exactly what I was thinking but why not just make a vibration analysis device on its own. Smaller and more transferrable. Plugged to the Rx and with on/off data recording capability through the TX

Thats EXACTLY what I was thinking of !

I still miss the point of the 3D. I find the V bar vib log giving plenty enough of info.

All rotary parts of a helicopter can cause vibes in any direction; for instance head dampers are capable of creating wobble on roll but as well as on the nick axis. I guess this applies for all frequencies since we are talking about rotary sources.

To me the only useful values are frequencies no matter which direction they come from

But probably I could be missing something and eager as I am to learn, I d like to know

Some vibes around the 10k mark can be hard to distinguish between motor and tail - presuming the max vibrations are perpendicular to the shaft it might help localise down the source!

[mkovalcson]

Originally Posted by Mercuriell

Thats EXACTLY what I was thinking of !

I was trying to convince art to take the flight log information and make it available for telemetry. It is on the plan for the future.

[mkovalcson]

It turns out that Tom already has this in the works for the JLog 3.0.

So we will have a real time vibration telemetry value coming back and have vibration graphs we can look when we look at our log files later.

[Mercuriell]

WOW !

[mkovalcson]

Tom said that was a very crude prototype from 2013 and he is measuring vibrations on 3 axis just like we were asking for.

The JLog 3.0 got pushed back because of the demand to get telemetry to the masses with the JLog 2.5 and 2.6. I think the JLog 3.0 will probably be a lot cooler because of the wait. I assume the next thing to be released will be the 16S battery monitor that he said was waiting on a component and is just now hitting production.

[Inverse]

What is the Jlog exactly? I took a look at the site and saw an inforgraphic with about 50 different items and a hundred arrows that looked like a bunch of Octopus having intimate relations.
It was information overload and I just clicked close.

[Mercuriell]

Originally Posted by Inverse

What is the Jlog exactly? I took a look at the site and saw an inforgraphic with about 50 different items and a hundred arrows that looked like a bunch of Octopus having intimate relations.
It was information overload and I just clicked close.

It's half a postage stamp of electronic genius made by R2 prototyping and designed by Tom. Basically it was the first available way of plugging into a power jive and extracting ESC data which was recorded onto a miniSD. Subsequent JLOGs have enabled Kosmik data recording and more latterly hooking up,to most makes of radio for telemetry.