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01-05-2016, 04:53 PM | #41 (permalink) | ||
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Swashplate tilting problem on position hold
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I suggest that you double check the wreackage in search of a ball link connector installed the wrong side or even if it is correctly installed, verify if it is not holding well enough. Good luck with your search! Carlos |
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01-05-2016, 05:25 PM | #42 (permalink) |
Join Date: Mar 2007
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=] I think the biggest clue here Carlos, is it entered an induced vibration state which lead to mechanical failure, rather quickly by the look of it.
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01-05-2016, 06:57 PM | #43 (permalink) |
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Georgi, except if the OP find obvious evidences of mechanical failure, it will be hard to prove the correct order of events in this incident.
You suggest that the clue is that it entered an induced vibration state which lead to mechanical failure, but it could very well be the other way around, a mechanical failure which induced a vibration state. Actually, it makes perfect sense, if we assume that the FBL would go nuts trying to compensate such odd behaviour, don't you think so? Carlos |
01-05-2016, 10:14 PM | #44 (permalink) | |
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Yea this is part of the highway between two cities, thats why looks vast. |
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01-05-2016, 10:16 PM | #45 (permalink) | |
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01-05-2016, 10:20 PM | #46 (permalink) | |
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01-05-2016, 10:45 PM | #47 (permalink) | ||
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Here is the video of me flying the scale fuselage eurocopter tiger 600 on the SK-720 before I have thought about adding the damn GPS. It was flying great for almost a year.sorry its not a complete video as my friend stuggled in transferring the video from her iphone.
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01-06-2016, 07:54 AM | #48 (permalink) |
Join Date: Mar 2007
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=] Fresh head today! Art quite rightly thinks I'm looking into this too deeply, because I do exhaust everything!
It would seem, because of the unusually low flight control rates, mixed with high bell gains gives a swash output angle from bell alone at well over double (150% more) what is normally applied by the gyro. So, in this case the heli flies well (non-GPS assisted) and has no issues because your stick inputs use low angled swash outputs. But, the gps will exceed (because of the above settings) (more than double) the swash angles (compared to normal settings) when a GPS command is given, position hold is hell bent to arrest any motion, so this results in what I imagine to be a fairly aggressive overdrive? I think where you need to be looking, on the bench, overdrive the swash angles and observe the linkages, especially the swash drivers as the head is being rotated, can you pop a link off? To me the heli failed during the initial elevator system command to hold position. I hope you are following me here, we can discuss if you need to. very best. georgi.
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01-06-2016, 09:28 AM | #49 (permalink) | |
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I have shown earlier a video of the GPS behaviour on the swashplate and how things can go extreme once I flipped the switch to PH. On the bench though, there is no bending happening on the connecting rods whats so ever, except may be on PH, where the GPS takes overcontrol. I have shown that to Art and he replied then that this is a normal behaviour of the swashplate. Now the thing that I want to do is to verify on the bench ONLY if I can predict that every thing is set right with GPS connected, since as far as I know that this previous statement is NOT possible then my next optoin would be to give up on the GPS, till I find a solid way or technique or whatever is to verify on the BENCH that every thing is working smoothly. Another cheap way to do so would be to experiment on T-Rex 450 with 4 rotor blades, despite the variables between the two machines, I still believe that it could give me an insight of the GPS parameters and how they suppose to be set/gain on 4 rotor blade helis. Bottom line. No GPS on my ship unless I can find a way to verify the GPS is acting normally or may be Art be generous and set the values for the multiblade head and have this as a default values to start with :p |
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01-06-2016, 10:21 AM | #50 (permalink) |
Join Date: Mar 2007
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=] to be clear, what I'm saying is had the scale profile control rates been set (120 deg/sec) with bell at 25-50% your experience would have been vastly different, so until this is set the swash will continue to behave as it did....
bringing another heli into it doesn't help much, and I understand your trepidations to repeat this event, completely. I fly a 1/6th scale heli, it would destroy my interest in this hobby should anything go south... I setup the SW for agility (to give the gyro its authority) and detune the Tx settings for the response I want, awesome! we know the gps caused this mishap, not by itself I feel confident of that, but because of what it was working with, inadequate controls that resulted in a mechanical catastrophe, sadly... It's important for me to satisfy myself we have nailed it, if I'm missing something, then I need to look again, so your input is paramount here, I appreciate given my above statement, you are approaching this in a mature way, thank you... georgi.
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01-06-2016, 10:25 AM | #51 (permalink) |
Join Date: Mar 2007
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=] we already have a scale profile you can choose from the SW?
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01-07-2016, 08:57 AM | #52 (permalink) | |
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I will apply your gains suggestions, and will see how its behaving, I have orderd a new metal 4 bladed head from century heli and waiting for it to arrive. I will set the gain properly then will do the test for the mechanics, if every thing flies okay will have to fix the fuselage. Since its fiberglass I needed the fiberglass repair kit that is usually used to repair boats and cars. Will fix the fuselage as good as I can then will fit the mechanics in. Now here it is comes the scary part, do I have to trust our conclusions and put the GPS on and do a flying test on the mechanics ??!! , I dont know, I feel thats should be done by R & D , not me though :p |
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01-07-2016, 08:59 AM | #53 (permalink) | |
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But with GPS its a self destructions dilemma !! |
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01-07-2016, 10:42 AM | #54 (permalink) |
Join Date: Mar 2007
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=] Not sure what to say, that's rare! I feel highly confident this event would not have occurred had the GPS been using settings it was designed for on your ship.
If it were me I would go again cautiously, altitude was of no real use here, in fact probably made matters much worse. My advice? get it on the 450 to GPS familiarize yourself, lets fit a Gov to the 600 and map the headspeeds to avoid bogging. Use the basic flight templates without any reductions, post a bench log where we can access your settings prior to flights. I've used pos hold at half a metre to evaluate it's performance, it was fine. I'm more than happy to support you should you wish to try again, but can understand if you choose to decline! On the repair if you haven't used it before, try Davids P38 filler it's awesome to work with! best.
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01-07-2016, 11:45 AM | #55 (permalink) | ||
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I don't buy this whole idea! There is no logic in saying that the GPS has caused this incident, except in case that the unit was defective. You have to keep in mind that our main concern before installing ANY bail out system is to make sure that the heli is mechanically able to support extreme maneuvers, as the recovery may be fairly violent for the heli, and so it helps if the heli meets requirements of being a fairly robust and agile 3D machine, if it is to be able to recover from any attitude, EVEN if you have no intention to fly that hard your scale machine. However, back to the question, considering the fact that there is no clear understanding of what exactly has caused the machine to plummet to earth, I'd suggest you to send both units (SK720 and the GPS) to be professionally checked/serviced by Skookum before using it again. Carlos |
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01-07-2016, 12:11 PM | #56 (permalink) | |
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Checked the old ones I have from other rotor head (all from the same brand). Then realised that I could assemble a complete head using only parts and pieces from old units. I might use that head for testing with GPS on, if every thing goes okay, and I regain the trust on the GPS then will fit the brand new head that I have just orderd. On a side note, thanks alot for offering to help, as I might need it soon ! |
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01-07-2016, 12:26 PM | #57 (permalink) | |
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So it is NOT going to take any aggressive baheviour which includes the rescue features and so on. The only two features to be used on this head would be PH and return to home. |
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01-08-2016, 08:57 PM | #58 (permalink) |
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Forgive me for being obtuse and trust me my intentions are genuine , but I learned a lesson when I used to fly the 720bk with a power bus. That is less is more. I truly believe in this. I used to run the sk power bus with the remote switch and all the cool cables neatly going back and forth. One day I took it all off and went direct into the 720bk, got rid of the stainless pick and the soft tape and I swear it flew way better. And the install was way cleaner, power lines direct to 720bk, all servos directly in, hard mikado tape. Vibes were absolutely no higher bird flew beautiful.
If you can fly, and obviously you can, why are you interested in taking it up then flipping a switch for it to stay in one spot ? If you're not confident enough yet with such a big bird I would never trust it to a self flying gps system especially when it's a known fact it's vibe sensitive. What if you've done everything right and SK has no glitch but something on the machine lets go and you get a vibe that throws off the 720. I dunno. I just believe in clean and pure. |
01-08-2016, 11:09 PM | #59 (permalink) | |
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You are totally right, however adding the GPS here was not because I am not confident in flying it, it was simply to make it cooler, lol l, it was for the return home feature mainly. I was looking in doing another test, but it seems I have to postponed that since the old head parts is missing some parts. And so will have to stay without GPS for a while till I order that missing piece, then I might do the test with GPS on. But yea I see your point here, GPS is NOT a security add on whatsoever, in matter of fact it adds a vulnerable point of failure ! |
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01-09-2016, 05:09 AM | #60 (permalink) | |
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Swashplate tilting problem on position hold
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I don't quite agree with your statement saying that GPS is not a security add on and that it adds a point of failure to the system; It can only be true IF you don't need any of the GPS functions. You didn't mention, but the GPS module has a cool feature called Hard Deck which enables the SK to perform automatic bail out recoveries in case that your heli is heading to a predefined minimum altitude regardless of remote settings or pilot's actions. IMO, this sole function makes the GPS module be worth the investment and the added point of failure (as you've mentioned), especially true in your case that you're flying a scale model. Carlos |
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