ralarcon Posted November 4, 2014 Report Share Posted November 4, 2014 --------------------------------------------------------------- -------------------------------------------------------------------------------- Hi Bill, Your understanding is correct. Sincerely, Dave Armando Director of Maintenance Flight Design USA (860) 963-7272 www.flightdesignusa.com ------------------------------------------ On 11/3/2014 4:02 PM, Bill Ince wrote: Hi Dave, I saw this post on the CT Flier Forum site today. The post was authored by “100Hamburger”. Can you please post a forum comment, if this information is correct or false? I think he is putting out false information. The thread title is “Dynon SkyView V10”, page 2, post #25. It is my understanding that “gusty winds and turbulence” will not “break loose” a servo. If the system cannot handle the turbulence, the servo merely “slips,” and a SkyView message will indicate that. On the other hand, if the servo freezes or becomes jammed, the “pin” he is referring to, will shear, allowing the pilot to override the servo. Thank you in advance, Bill Interesting, Thanks for the info. Cheers Link to comment Share on other sites More sharing options...
Anticept Posted November 4, 2014 Report Share Posted November 4, 2014 Figured I would put this out there:Shear pins are used in a LOT of places on aircraft. In general: starters, magnetos, generators, tach drives, servos, hydraulic pumps, pretty much anything that if failed, it would not cause immediate unsafe conditions in *other* systems. They also are meant to be strong, and only fail if it becomes a "The powering device (motor or engine) or the device are going to be destroyed if the linkage is not broken" type of last-resort failsafe.Due to the nature of autopilots, they MUST have a clutch and a shear pin, as regulations everywhere require that the pilot be able to mechanically overpower the system. They could just use a shear pin, but then everyone would get mad at the maker for breaking them Link to comment Share on other sites More sharing options...
Tom Baker Posted November 4, 2014 Report Share Posted November 4, 2014 Just for the record. I have personal experience with it....and you once again show your ignorance over this aircraft. Dynon techs admitted the standard servos are not suitable for high winds or sudden strong turbulence. To get those kind of servos, one needs to upgrade to servos that can handle much heavier aircraft. I had a pitch servo break loose twice in gusts at 10k feet. The servos are designed with a load pin that breaks if the gust is strong enough to damage the servos or interfere with control of the aircraft. Luckily the pins remained intact and I was able to respond quickly and retake control after the servo released and the nose pitched down suddenly. You know if you had the airplane in trim, you likely wouldn't have gotten the pitch down when the serve slipped. If the servo is disengaged and the trim is not set the airplane will try and go to the attitude it is trimmed for. Link to comment Share on other sites More sharing options...
Duane Jefts Posted November 5, 2014 Report Share Posted November 5, 2014 The plane was trimmed as the autopilot messaged. There is no way to trim a plane in autopilot mode by feel since you are not on the stick yourself. So you depend entirely on the autopilot to sense and message for the trim. The pitch down was clearly due to the pitch servo being overpowered. How Dynon handles that is a function of their design. The point being, if you are running with Dynon autopilot and servos be aware the standard issue is not industrial strength and there is a tipping point in regard to xwind and turbulence for them... I no longer use the autopilot when in turbulent conditions. And I always have my hand near the stick when in autopilot mode now in case of clear air turbulence. I have no intention of upgrading the servos....I will sell the plane before I do that... Have you had your autopilot servo mount degaussed? Have had problems here with a magnetic mount causing the dynon to say to trim up when, in fact, it was in trim. It causes the servo to slip and the airplane to wander when connected to the autopilot. Degaussing the servo mount fixed it for a while but now the problem is back. We are trouble shooting. Flight Design said a year ago that they would replace the mount with a non ferrous one but... More info to follow. Link to comment Share on other sites More sharing options...
Michael Schofield Posted November 6, 2014 Report Share Posted November 6, 2014 A couple of quick thoughts from Dynon: Bill's got it: the servos have limited control authority by design. This is a safety feature so that should something go wrong, the servo will "slip" before it's applying a silly amount of force, and as indicated above, that's NOT the shear pin breaking. Basically, think of the servo as your hand on the controls. It can give "so much" force, and then it wants trim to deals with configuration or power changes. As you know, we have trim annunciation that tells you what the servo needs to not work so hard, but as some of you also know, it's not perfect and can be disturbed by local magnetized things (like the limiting bracket). SkyView version 11.1 improves the trim-sensing drastically, and I know that Flight Design is working on qualifying it as an approved update from the current 6.2 version. I don't speak for Flight Design, so I can't make promises around availability, but we're working behind the scenes to help get the settings and configurational stuff worked out. Occasional slips in moderate+ turbulence are not unexpected. But if you're getting them regularly, ensuring the torque is turned up sufficiently (this is usually already at 100%) is one thing that can be checked. The 11.1 changes will, in some cases, cause less slips to happen as well, so that may improve overall slip behavior for some people. On a more technical note, when the servo "slips", there isn't any clutch or anything actively mechanical involved. This is also a safety feature - no additional moving parts that can, when they fail, cause their own issue. Simply put, the type of electric motor that is on our servo - a stepper motor - can put out a certain amount of torque. When the torque it can provide is overcome, either by turbulence or by you moving it by hand (try it some time), the external force wins. Even though it can feel somewhat like a clutch or breakaway, it's really just the external force overcoming the electromagnetic forces of the motor trying to hold what it wants. I'm also sad to learn that Roger Heller passed away. I went down to one or two of the early CT gatherings he held in McMinnville. He flew me around all weekend (I didn't have an airplane at the time). My condolences to the community here. Michael Schofield Marketing Manager Dynon Avionics Link to comment Share on other sites More sharing options...
Doug G. Posted November 7, 2014 Report Share Posted November 7, 2014 It is always nice when the experts correct the bad info. Thanks Mike. Link to comment Share on other sites More sharing options...
WmInce Posted November 7, 2014 Report Share Posted November 7, 2014 Thank you Mike. Link to comment Share on other sites More sharing options...
WmInce Posted November 7, 2014 Report Share Posted November 7, 2014 He restated what I said to begin with...More BS.Narcissism to the max. You deleted your original post. Here is your 2nd post: 100Hamburger, on 03 Nov 2014 - 3:17 PM, said: Just for the record. I have personal experience with it....and you once again show your ignorance over this aircraft. Dynon techs admitted the standard servos are not suitable for high winds or sudden strong turbulence. To get those kind of servos, one needs to upgrade to servos that can handle much heavier aircraft. I had a pitch servo break loose twice in gusts at 10k feet. The servos are designed with a load pin that breaks if the gust is strong enough to damage the servos or interfere with control of the aircraft. Luckily the pins remained intact and I was able to respond quickly and retake control after the servo released and the nose pitched down suddenly. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted November 7, 2014 Report Share Posted November 7, 2014 He restated what I said to begin with... "safety feature so that should something go wrong, the servo will "slip" before it's applying a silly amount of force", translation: the servo slip in sudden turbulence is a 'feature'. The Dynon servos are not industrial strength and will cut loose in turbulence. When the pitch servo did that on my plane the nose pitched down hard, twice. The shear pins held (in part because I did not jerk the stick back before releasing the autopilot) but understand the experience feels like a total servo fail, not a 'slip'. If you are prudent and flying with these servos you have two choices...1. get stronger servos 2. do not use the autopilot in strong turbulence, or in air that you suspect may give a sudden upthrust of turbulence (hot summer days in the desert). If you are not prudent you run the risk of scaring yourself and your passenger and possibly worse. Sigh... The servos used by Dynon are stepper motors similar if not virtually identical to the ones that TruTrak uses. These have been used in *many* applications, in much heavier aircraft than a CT, and in all sorts of conditions including moderate to severe turbulence. Yes, the motor may slip if it encounters severe forces. This is a momentary condition and might cause a slight bump to be felt. But the motor is still applying force, and has not just "given up". It will not cause a serious change in attitude, unless the system is very out of trim or there is a problem with the system setup or the servo hardware itself. Personally, I have never had my TruTrak servos slip when it was in trim, even in very bumpy air. If you are in moderate turbulence and experiencing pitch excursions significant enough to "scare" you, then you have a problem somewhere in your system (or else you are overly prone to being scared). Taking a dump on Dynon and their tested and proven hardware is really not the way to handle this. If you have engineering data including force and moment calculations that show the Dynon servos to be inadequate for the application of use in a CT, please post that analysis with all mathematics for review. Otherwise you are just trolling and making unjustified claims against a well respected vendor and their products. Link to comment Share on other sites More sharing options...
Roger Lee Posted November 7, 2014 Report Share Posted November 7, 2014 You can buy from Dynon or others servos with lower or high torque values. These servos also have shear pins that will break if too much force is applied either from a pilot or turbulence. I have replaced two shear pins. Link to comment Share on other sites More sharing options...
Anticept Posted November 7, 2014 Report Share Posted November 7, 2014 By the way everyone: The autopilot system used by dynon and flight design are directly linked to the pitch control (more on this in a minute). If you watch for indicators on your AP, it might tell you the force it is applying to the controls. I personally move the trim to help keep the load off of the servo. In larger aircraft, such as my mooney, autopilots do not move the pitch control surface, but instead move the trim. This allows for very lightweight servos. I do kindof wish my CT had trim AP instead of direct link... Link to comment Share on other sites More sharing options...
WmInce Posted November 7, 2014 Report Share Posted November 7, 2014 . . . "In larger aircraft, such as my mooney, autopilots do not move the pitch control surface, but instead move the trim. This allows for very lightweight servos. I do kind of wish my CT had trim AP instead of direct link..." . . . For RV-12's equipped with electric trim . . . automatic trim is available. That said, I see no reason why it should not eventually happen with comparable autopilot systems in the CT fleet. Of course, it requires an electric trim function. Auto-trimming is great. Especially during long cross-country legs . . . reduces fatigue substantially. Link to comment Share on other sites More sharing options...
WmInce Posted December 15, 2014 Report Share Posted December 15, 2014 . . . "FD GmbH has produced and is flight testing the latest software version 11.1. It is at Dynon for final vetting now.The POH Supplements are in final review. I would estimate that in November they will be released." . . . Does anybody know what the status is on this? Link to comment Share on other sites More sharing options...
Duane Jefts Posted December 15, 2014 Report Share Posted December 15, 2014 Does anybody know what the status is on this? 2 weeks ago Dave A at FDUSA said by the end of Sept. He was joking. Since that was long past they are saying in the next couple weeks. That "in the next couple weeks" has been going on for 10 weeks. I'm guessing sometime after the first of the year. Link to comment Share on other sites More sharing options...
WmInce Posted December 15, 2014 Report Share Posted December 15, 2014 2 weeks ago Dave A at FDUSA said by the end of Sept. He was joking. Since that was long past they are saying in the next couple weeks. That "in the next couple weeks" has been going on for 10 weeks. I'm guessing sometime after the first of the year. Thanks Duane. Link to comment Share on other sites More sharing options...
gbigs Posted December 15, 2014 Author Report Share Posted December 15, 2014 You can buy from Dynon or others servos with lower or high torque values. These servos also have shear pins that will break if too much force is applied either from a pilot or turbulence. I have replaced two shear pins. Correct. And this is what I pointed out in my comments. The stock servos FD provides are the weaker servos. Link to comment Share on other sites More sharing options...
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