Fly Bar Less on a 2 stage turbine

[Jamiem]

I've been flying a T-Rex 700 with a wren44 conversion, using a V-Bar V5.1 and have had zero issues, and in fact using a bluetooth dongle have checked the in flight vibes and they are unbelievably low. On my old 700LE FBL nitro (the exact same setup as this turbine, but with a YS 91SR), I had around 1500 registering on the real time vibe analyser, on this turbine, it was less than 100 in the hover! Superb!

YouTube

YouTube

[Coolice]

Originally Posted by Laurens

True about the blue vs black Vbars. I've heard a couple stories of the Logo 400, which is an electric heli. Its quite sensitive to vibrations. On the black Vbar, you'll have more problems with vibrations regardless of the software. The blue version should be a lot more vibration resistant.

What I'm wondering, I had a Predator with CF landing gear and alu frames. I was flying flybarred, but still using a gyro. Why is a one axis gyro untouched by the vibrations, but a 3 axis gyro not?

Hey Laurens.

Bear in mind that most tail gyros are normally mounted with thicker foam pads and/or with a steel vibration attenuation plate sandwiched between two foam pads. The current school of thought with fbl units is that they need to be more rigidly mounted to be more effective, as you know though this allows more problems to arise through vibrations.
.

[MattJenner]

Hi guys
This will confirm what was prev posted.
HC do actually make a an acoustic foam cover for their units,
Which they insist you should use on all turbine models.
A guy down my club has just purchased a HC unit and he let me take a picture of these instructions
He also sent me a screen grab from the instruction talking about ultra sonic protection here is a link sending you to the HC site where they also refer to this foam as an ultra sonic protection against turbine noise..

http://shop.rc-electronic.com/e-vend...61&c=866&p=866
It is interesting, the line on their site confirms what Bellbloke commented, if you use it in a fuse it still may not be enough protection..
The HC-X series is prepared for using in turbine models due to internal ultrasonic protection features. Depending on individual construction and fuselage style this protection could be not adequate.

interesting info i thought.. if i get one i will try on electric

[cbergen]

Excellent product service by Captron, finding a cause and coming up with a fix for an issue that may affect a very small percentage of helicopter pilots, Kudos.

[Cletus]

Just caught up on some Helifreak reading and came across this thread.
So Here's my perspective on the issue:
I was happily flying my Intrepid MW-54 Turbine heli flybared until IRCHA 2010 when I decided to upgrade to Flybarless with a Skookum 720. Found out the SK720 would do some crazy, spooky, unexpected, hard left, aileron rolls on takeoff and I believe was responsible for my first crash of that bird, when it did this in flight and and on recovery, somehow setup an absolutely wild vibration situation. I rebuilt the bird and switched to Vbar Black Sensor got some decent results at first but there was some weird twitching in fwd flight at times.
I then switched to Vbar Blue line sensor on the advice of Mr. Mel as he advised it was less sensitive to vibration issues. I had very many perfect and enjoyable flights with that setup, I was flying it as my favorite bird every weekend ...flew like it was on rails.

Packed it up and shipped it off to IRCHA 2011. On setting up at IRCHA there were some vibe issues during the first flights and Lou and myself worked feverishly on resolving that and also tweaking the Vbar governor feature that we both were playing with. We got the vibe thing sorted and Lou had it in a perfect over, then he announced that he had absolutely no control of the aircraft. I was standing right next to him spotting.

Suddenly, the bird started backing-up towards us and just as I realized this and before I could say OH F#%K, there was the boom-strike, parts were flying all over the place (the boom and tail-section was recovered over at the flight station to our left, I recovered other bits and pieced about 100' forward of the flight line ....it was frigging spectacular! ...never seen anything like it!
I inspected the wreckage immediately and noted a loose power connection to the Vbar. Downloading and analyzing the flight-log, confirmed a Vbar reset, multiple times in-flight. I can only conclude that all the previous vibes "walked" the power connector loose from the Vbar unit and from then on, there were in-flight power interruptions.
The engine was fine, but I took the opportunity to have Wren USA overhaul it anyways. I will be rebuilding the bird starting with a new airframe kit, but this time I'm keeping it simple and flybared, the only upgrades will be The Jewel Dual-output Generator and a Spartan Quark Gyro (originally had a GY-401 Gyro when it had the flybar).

[Vortexx]

What a shocker.......I couldn't believe it when the heli took off and smacked the ground.....

I have been flying a MA Spectra fitted with a Wren44 and a blue V-Bar and have over 26hrs on it now and had no problems.

I hope you get it sorted and can get to enjoy it.

Regards,

Lance

[NevB]

Originally Posted by cbergen

Personally, I don't use any electronic stabilization on my FBL birds, Proper setup, proper blades, and simply flying the helicopter makes it possible. Once used to the flying characteristics, it's really not a big deal. But YMMV....

Hi Chris,

Just developing an interest in turbine helis and read your interesting comment.

I was under the impression that FFF was possible without electronic FBL stabilization, but 3D was a problem. Can you perform all the usual 3D moves on your turbine birds with no FBL electronics?

Regards

[cbergen]

I can.

This video is of my gasser, but the Turbine flies just the same.

YouTube

YouTube

[NevB]

Originally Posted by cbergen

I can.

This video is of my gasser, but the Turbine flies just the same.

http://www.youtube.com/watch?v=8L045...e1AUAAAAAAAxAA

Excellent!

[desertstalker]

Originally Posted by Cletus

I inspected the wreckage immediately and noted a loose power connection to the Vbar. Downloading and analyzing the flight-log, confirmed a Vbar reset, multiple times in-flight. I can only conclude that all the previous vibes "walked" the power connector loose from the Vbar unit and from then on, there were in-flight power interruptions.

Its not really the VBars fault that the power connector came loose, same result if it had been power feed to the RX in a normal FB setup.

[cbergen]

True, but it's a whole slew of more connections that one has to be concerned with coming apart, another electronic unit to worry about failing.

I've never heard of a flybar complain about vibrations...

[desertstalker]

Originally Posted by cbergen

True, but it's a whole slew of more connections that one has to be concerned with coming apart, another electronic unit to worry about failing.

I've never heard of a flybar complain about vibrations...

If you use the VBar (or similar) you have either 2 spek sats or a single SBUS link to the FBL then the normal servo and power connections, I dont see any significant difference. If you are using a different radio system then yes the RX->FBL links are a factor but most seem to use either spektrum/JR or Futaba.

Agreed on the vibrations, but they didnt cause the VBar to fail (in the incident i was speaking of), they caused a plug to fail which could happen just as easily as on a normal RX. Vibrations can also be worked around, the Futaba CGY750 is capable on everything but a turbine (perhaps) and afaik both Helicommand and Gyrobot (i think) make units specifically meant for turbines (granted they are not especially cheap but I doubt anyone who can afford a turbine will be put off by another $200 over a VBar).

[Cletus]

Allow me to clarify here:
I DO NOT blame Vbar at all for the incident. I flew it like it was on rails with the Vbar in Trinidad for many months and totally enjoyed it. In fact a couple of us were playing with using the Vbar governor feature, with increasing success at IRCHA dialing it in for managing the Turbine.
I am convinced that a vibe problem which developed after shipping the heli to IRCHA caused the connector to "loosen-up" and eventually back-out after the vibe issue was resolved. After the crash, it was indeed so found, and the Vbar log file for that flight DID CONFIRM three momentary power disruptions/Vbar resets in-flight.
For the new machine, It's just my choice to stay with the flybared head and to keep the model stock and enjoy it the same as I enjoy my gasser

[MattJenner]

Hi Folks, Bell Bloke here on Matts page

Here's an update regarding the issue at the start of this thread which was the unexplained multiple crashes of this poor Predator owners turbine. As a result it was finally put down to an incompatability between the Skookum FBL unit and the 2 stage engine due to ultrasonic frequencies.
Here is a link, scroll down and read at the bottom:
http://www.digitalflybar.com/product...arless-system/
Fair play to Skookum for putting this on their site, if only the others would do the same.

Helicommand fixed the issue on their system they have insulated the unit inside and done a firmware update so all units from V113 onwards are ok with 2 stage engines although they do still recommend you use the foam hood, and I would still keep it well away from the engine induction if you can.

Gyrobot is also ok with 2 stage engines as they do a spectial unit that is designed just for 2 stage engines, so they too know about the issue.

If you have a FBL system and its on a 2 stage it might be an idea as a point of safety to really check that your system is compatable. It maybe that you have never had an issue due to chance placement of the unit, but it may also be so that everytime you fly you've dodged a bullet.
Just my thoughts, good luck Gents.
Regards Bell Bloke.

(Thanks Matt for letting me use your log in)

[Cletus]

I found that out the hard way, when I first went flybarless on the turbine. The first FBL system I initially installed was a Skookum SK720 and it did not like it at all. It would suddenly and unexpectedly apply hard left aileron just as the skids came off the ground ........very scary crap!
Skookum graciously replaced it twice in an attempt to resolve the issue. I now have it installed on my 3-bladed, electric Airstar AS350 where it works just fine.