START HERE |
|
Register | FAQ | PM | Events | Groups | Blogs | Calendar | Mark Forums Read |
Unregistered
|
Turbine Helicopters Turbine R/C Helicopters |
|
LinkBack | Thread Tools | Display Modes |
12-27-2011, 06:49 PM | #21 (permalink) |
Registered Users
Join Date: Aug 2008
|
I only know too well about vibration issues with my predator turbine.After one year of trying everything to resolve it i gave up and it's been relegated to a corner of the garage for weeks now.I'm having more fun with an electric 450 now.
|
Sponsored Links | |||
Advertisement |
|
12-27-2011, 08:00 PM | #22 (permalink) |
Registered Users
Thread Starter
Join Date: Jul 2011
|
Helibeli
Is that the predator where you are using the Vario undercarridge ? There is no vibration on mine at all, hence the reason it is still flying after 80 hrs, the best conversion I have ever flown, well over engineered mechanics, capable of a lot of lifting and heavy pay loads.. Matt
__________________
Have Fun |
12-28-2011, 10:43 AM | #23 (permalink) |
Registered Users
Join Date: Aug 2008
|
It was doing it with the original undercarriage,with the vario undercarriage on floats and on foam blocks.The critical rpm was 940 when it would start to shake and oscillate violently.Most of the head has been replaced,different dampers,different new blades,all with the same result.With just the flybar i can take it up to 1600 rpm with no vibes at all.I think it's a frame resonance problem(not a lead/lag issue) I've added some strengthening 6mmx0.5mm stainless tubing from the top bearing block to various points below and at other places to see what happens but i've yet to test it.At the moment i've been won over by a 450 electric(never had as much enjoyment for years in this hobby)
|
12-28-2011, 11:27 AM | #24 (permalink) |
Registered Users
|
For everyone interested, the heli of this topic is being discussed here:
https://www.helifreak.com/showthread.php?t=313537
__________________
Logo 800/Jeti DS16 |
12-28-2011, 01:59 PM | #25 (permalink) |
Registered Users
Thread Starter
Join Date: Jul 2011
|
did not realise Ian had started a thread,
I will close this one so it saves everyone looking at two different forums Matt
__________________
Have Fun |
12-30-2011, 10:48 AM | #26 (permalink) |
Registered Users
Thread Starter
Join Date: Jul 2011
|
thanks Chris for PM on how to re open the thread.
Matt
__________________
Have Fun |
12-30-2011, 10:50 AM | #27 (permalink) |
Registered Users
Thread Starter
Join Date: Jul 2011
|
The data downloads that I did from one make of unit (not dji or Helicommand) showed that the unit was affected more the higher the rpm of the engine, anything over 100,000 was enough to put it in the danger zone.
2 stage engines are more powerfull than single stage engines so it is for this reason that single stage engines have to be much larger to deliver the same amount of power. The by product of this is that larger engines do run slower and so this is why they give less trouble when used with certain systems. Whilst testing one unit we found that placement is the key. The unit should be as far away from the induction noise of the engine as possible and as a double measure sound deadening foam placed around the unit if you really want to be safe. For scale flyers the unit would have to be inside the fuse. The problem with this is that it's a sound box and in this scenario moving it away from the engine induction MIGHT NOT be enough. So, total sound isolation with accustic foam is the best way to be sure. With the use of accoustic foam I managed to get the 'noise' to the unit BELOW that of an electric machine! The only problem I can see is that of a data printout...not all units allow access to this, so you would be working blind with some units. However 2inches of foam around the unit is a very cheap insurance and will certainly hold the balance in your favour against any kind of induction noise, be it 2 stage or single stage. In most cases these units are out on the boom away from the engine and not inside a canopy of any kind, this is fine. Hope this helps to save a few turbines at least. Comments are From Bell Bloke who was testing these units 5 years ago, he posted on RR and I thought it was an idea to post his info here. Matt
__________________
Have Fun |
12-30-2011, 11:20 AM | #28 (permalink) | |
Registered Users
Join Date: Jun 2004
|
Quote:
The issues are vibration related, I well remember the predator having a buzzing throught the frames from the idling gearbox and turbine, let alone when it's throttled up over 150k. Perhaps the introduction of foam sound deadening dampens the vibes rather than sound, there is a similar trick with car stereos, you can buy a heavy and dense material used to add mass to light body panels which stops them resonating. In the video the gyro sensor was mounted onto a metal platform, directly above a fast rotating turbine which is one cause for major problems. The next was the stiff under carriage combined with a hard surface feeding back into the air frame. Mikado are working on a more vibration tolerant sensor, but details are sketchy. In the meantime sensor placement is crucial. . |
|
12-30-2011, 11:34 AM | #29 (permalink) |
Registered Users
|
Interesting!!
Would the choice of frame material possibly have an affect as well? Obviously I'm a big fan of G10 frames, and as I have expressed with Gasser models, that it has a vibration deadening affect. Is it possible why we haven't seen as many issues with FBL systems in our Turbines? (notwithstanding the incident at IRCHA, which we believe was an internal solder problem on that one unit)....
__________________
Chris D. Bergen Bergen R/C Helicopters |
12-30-2011, 01:35 PM | #30 (permalink) |
HF Support
|
I'd forgotten about this thread and after reading it again, I've got some trepidation in regards to spooling up my (almost) repaired Intrepid with it's new V-bar setup.. The unit I have is a couple years old and NOT one of the new Bluelines, but it does have the black sensor and I was able to upgrade to 5.1Pro..
Chris, do you recall what Cletus was running on his? Lou is all Skookum, right?
__________________
-Kevin No helicopters were harmed in the creation of this post. AMA CD # 7309, Turbine Waiver# RW 890 Click Here For Bergen Intrepid Turbine Build Videos |
12-30-2011, 01:39 PM | #31 (permalink) | ||
Registered Users
Join Date: Jun 2004
|
Quote:
Long time no speak buddy, how you keeping? Yes, from what I know I'd say you are right. The frame material will play a big part in exactly how much vibration gets transfered aroudn the mechanics, G10 absorbes more vibration than Carbon for instance which is much stiffer. Having said this it's got to be something to do with the fibres used in the composite as even G10 can be made quite rigid from memory. The Predator in the video was fitted with the nice looking carbon U/C struts, but they are very rigid from memory and will not allow any real give to absorbe some of the vibes generated by ground resonance. The metal frames will only serve to transmit the vibration throughout the model rather than dissipate it and/or minimise it going too far through the frames. Quote:
The newer Blue Line sensors are more tolerant to vibrations I am lead to believe than the older black sensor, quite why I do not know but it's well known apparently. . |
||
12-30-2011, 02:10 PM | #32 (permalink) |
Registered Users
Thread Starter
Join Date: Jul 2011
|
Hi Guys, Bell Bloke here, posting under Matts name since I don't have an account here now. Just thought I'd tell you of my expierience on this.
I've been aware of this problem for about 6 years now, and when 2 years ago helicommand were having issues which they have now fixed, it was no surprise. The problem is caused by turbine induction HF as it goes over 100,000rpm and strikes the casing of the various units we have tried. Some are more sensitve than others and in some cases mearly moving the unit to the tail boom is enough to fix the problem. Some makes allow for you to see the effect the turbine HF noise is having on the unit by means of a download. This is great and allows you keep the unit in the accoustic safe zone. It's fair to say that some folks have flown without issue simply because the unit is not in close to the induction side of the engine (exhaust is ok) or is outside the helicopter ie on the boom. Scale boys or those who put these units inside a fuse or canopy or near to the engine run a very serious risk of an issue. Like anything in this game it is possible to think all is well until it's not and you crash. I've had 2 people down who said they wanted to put these systems on, both put them in the canopy against my recommendations and near the engine (the worst place)...they crashed. Accoustic foam is the fix. It's interesting that 6 years ago and recently I had 2 different units do the same thing then and now. In a controlled test and without making any changes at all to the helicopter it was possible to see how by simply placing accoustic foam on the unit, the data readout went from CRITICAL to SAFE....amazing but true. That's 2 totally different systems on different machines then and now. So if you have a turbine and one of these units, keep it away from the turbine induction and out of a fuse or canopy and put it in an accoustically isolated box to be really sure. If you fly scale put it in a box with 3inches of foam around it and that will fix it, if you don't well you might be on borrowed time.... It's worth noting that some units are less sensitive than others to this problem, they are however all effected, but only a data download will tell how near the edge you are. I hope you can understand that this is a very big subject and I could bore you all with pages of detail here and test results showing this problem....but I wont...ha, ha. As for me, well I'm still sticking to old fashioned flying, don't quite trust these things yet and anyway, wheres the fun gone.. Anyway hope this helps some. Cheers Bell Bloke.
__________________
Have Fun |
12-30-2011, 02:30 PM | #33 (permalink) | |||
HF Support
|
Quote:
Quote:
Quote:
Good to see you and Matt back here.. Thx!
__________________
-Kevin No helicopters were harmed in the creation of this post. AMA CD # 7309, Turbine Waiver# RW 890 Click Here For Bergen Intrepid Turbine Build Videos |
|||
12-30-2011, 03:04 PM | #34 (permalink) |
Registered Users
|
I am unsure of which sensor Cletus was using, and unsure of what unit Lou is now using...Sorry..
__________________
Chris D. Bergen Bergen R/C Helicopters |
12-30-2011, 05:52 PM | #35 (permalink) |
Registered Users
|
I think Lou made the switch to Vbar and is using the blue sensor as am I. I thought Cletus was using the blue sensor also. I saw no problem at all on my 44 Magnum when it WAS flying.
__________________
Bergen Tazer 800, Bergen 44 Magnum, Trex 600E, Trex 600ESP, Trex 450SE AMA 727477 Turbine Waiver RW2070 |
12-30-2011, 06:30 PM | #36 (permalink) |
Registered Users
|
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?
__________________
Logo 800/Jeti DS16 |
12-30-2011, 06:38 PM | #37 (permalink) |
HF Support
|
I'm on the waiting list for a new Blueline Vbar. No big deal 'cuz I'm out of Tygon fuel tube and the LHS doesn't have any... Not going to be spooling this thing up any time soon...
Interesting question Laurens.. Stands to reason both single axis and triple axis units should be affected. Maybe something to do with the "plane" of the vibrations?
__________________
-Kevin No helicopters were harmed in the creation of this post. AMA CD # 7309, Turbine Waiver# RW 890 Click Here For Bergen Intrepid Turbine Build Videos |
12-30-2011, 06:43 PM | #38 (permalink) |
Registered Users
|
Somehow it would be the plane of vibration, but I think roll and yaw would be the first axes to notice, not the pitch/nick axis. And in flybarless, the pitch and roll axis are influenced by these vibrations, but I do not see a lot of rudder movement.
__________________
Logo 800/Jeti DS16 |
12-31-2011, 06:54 AM | #39 (permalink) |
Registered Users
|
Matt,
I have been flying both Vbar and Skookum for about two years on twin Bergen 44 Magnums. I have not experienced any issues. For simplicity I converted the Skookum to Vbar and continue to be trouble free. In fact we successfully tested using the governor function in both Vbar and Skookum with the Wren 44. Wasn't easy getting it set up, but once done it works pretty good. I plan on going out today and getting my last flights of the year in and will be flying the Vbared Magnum. I can't say that I've done anything scale, but you would think that unskilled 3D puts out maximum vibration and stress on a system. Happy New Year! Lou
__________________
Vector 550 Quad/Octo Multirotors DJI WooKong Multirotor Controllers Twin Bergen 44 Magnum Turbines - KERO Start FBL www.circlecityhelis.com |
12-31-2011, 07:04 AM | #40 (permalink) | |
Registered Users
|
Quote:
In the Intrepid MW54 the engine is forward facing with the FBL unit sitting in the same area next to the main shaft. I never had an issue with the MW54 either and that went from a Skookum SK360 to the SK720. Lou
__________________
Vector 550 Quad/Octo Multirotors DJI WooKong Multirotor Controllers Twin Bergen 44 Magnum Turbines - KERO Start FBL www.circlecityhelis.com |
|
Thread Tools | |
Display Modes | |
|
|