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Official RotorScale UH-1A Medic Green 450 Size Helicopter Discussion Thread

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  • Originally posted by Tom.MotionRC View Post
    Ridgerunner, We know you need 8 degrees of offset for a large heli using a Bavarian Demon. We think an 8 degree offset on this 450 using the Tarot would cause tail drift but have not tried it. We talked to the Tarot support team and were told to use a 0 degree offset. I feel a little caught in the middle and please don't think I'm saying you are wrong or challenging your knowledge. Just trying to get to the bottom of it. Have you tied both an 8 degree and 0 degree offset with the Tarot? This heli was designed with a 90 degree pitch lever. I'm told by the designer this was intended for a 0 degree offset. We had many of these out flying with 0 degree offset including the one used by James in his video. Again, we have not tried setting it at 8 degrees so I'm curious what you find.

    On the gain (AVCS Head Hold), we set it slightly high to start knowing we would need to dial it back. We neglected to mention this in the video and will edit and mention that. We expected a little wag and dialed it back a few clicks and eventually settled on 58. Thanks for mentioning that.
    First note I am going to be flying this in both rate mode and heading hold gyro modes. Also, a disclaimer: I have not yet flown this heli and I have never actually flown with any ZYX gyro. In fact, I have only recently graduated up to the 450 class after having flown only micros for the past six years. I do however, have a pretty deep understanding of the physics, electronics and software/firmware aspects of collective pitch RC helicopters having spent years devouring all of the knowledge I can from HeliFreak and other sources. Also note that I am a degreed engineer with decades of work experience in both the aerospace and systems software fields (I am recently retired). To learn about the ZYX-S2 gyro specifically, I recently spent a couple days digesting 5 years worth of posts written on both the gargantuan ZYX thread over on RCGroups and the Advanced ZYX tuning and troubleshooting thread on HeliFreak. In other words, I have a lot of book knowledge on the subject but very little hands on experience with this unit.

    That said, it is my understanding that the proper way to optimize the tail setup (for all helis sizes and all FBL controllers), is to first adjust the rudder linkage such that with the gyro set to rate mode and a lowish gain, the heli does not rotate in yaw (and will weathervane into any prevailing wind) when the Tx is sending out zero on the rudder channel, and the rudder servo horn is 90° to the linkage. To achieve this, the tail blades will have some amount of pre-set AOA to counter the rotor torque in a hover. This value is determined through trial and error, but the 8° value specified in the ZYX-S2 manual is probably a pretty good starting point. Once the zero torque balance point is established in rate mode, the plus and minus travel limits are then set to the maximum values achievable without binding (and with the ZYX-S2, this is done in the assistant software SETUP->TRAVEL page). Once the center point and limits are established, then the optimal heading hold gyro value is determined by starting off low, then working up to where the tail starts to wag in fast forward flight. Once the wagging point is determined, the gain is then dropped back down a couple clicks to where the wagging stops.

    Although it is true that a tail will hold just fine in heading hold mode with the blades set to zero pitch with the servo arms at 90° and the rudder channel centered, (and many 3D pilots who only fly in heading hold do set things up this way), this setup will simply not work in rate mode. If you talk to the scale heli pilots, you will discover that many of them also like to fly in rate mode.

    And +58 is still WAY too high for the heading hold gain value - as displayed in the ZYX-assistant SETUP MONITOR page. The channel output value on the Tx is NOT necessarily the same as the value you see on the MONITOR page - (e.g. a CH5 output value of 58 on a 0-100 scale Tx will result in a value of +16 on the MONITOR page and I'm guessing that this is what is happening with whomever is telling you that 58 is a good value).

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    • The ZYX gyro(and its variants) is really not up to scratch and never has been - that is the uncomfortable truth of the matter.

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      • Cyclone 7, I'm unsure why you say that. We've been using it on many 450 models used during testing for hundreds of flights per model - never had an issue in this application but we have not tried in other applications. We've been in contact with the developer and support team. Remember, these are not 3D helis. These are scale helis - a potentially different application and a different size compared to what you may be speaking of. Also note this is not a ZYX. This is a ZYXS2. We work very hard to design properly and test, test, test, and test again. We all have our opinions and preferences. There are many interlaced variables with helos that don't exist in airplanes. There are at least ten points of a helo setup that are potentially unique, and a handful of paths for each of those points that are different but will ultimately end up with a heli a specific person likes.

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        • All I can say is once you get these little 450's setup correctly with a good flight controller they are a blast. Even on a less then perfect day with 20mph gust! Mine has a Brain 2 in it, Yes a bit costly for an inexpensive heli but you cant put a price on fun right ? Lol

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          • You say the Huey was test flown,has it also been lubed and loctite applied?

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            • Originally posted by guitarman64266 View Post
              You say the Huey was test flown,has it also been lubed and loctite applied?
              It will still need lubrication and loctite applied.

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              • When will the ZYX setup video from Motionrc be back up? I saw that it was taken down.

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                • This might be of some help to you, in the meantime;

                  this video is for those who have basic setup knowledge if you need help just ask

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                  • Originally posted by Cyclone 7 View Post
                    This might be of some help to you, in the meantime;

                    https://www.youtube.com/watch?v=KlkonH1Vfzk
                    I watched that one and its... ok. But I found the following one to be be much more in-depth and helpful. Although this one covers the earlier ZYX version of the hardware and software, I found that much of what he discusses applies to the ZYX-S2. His six part: "Flybarless Conversion" series covers a lot of ground on the proper setup of a 450 heli. Highly recommended:

                    HK-450GT Flybarless Conversion - pt 4 - Radio and Software Setup


                    Note that I maidened my Rotorscale 450 Eurocopter today (see that thread for a vid). I started off with a HH gain value of +30 - it worked beautifully.

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                    • Tail Gyro setup update.
                      Ok, so I now have 8 flights under my belt with the Rotorscale AS-350. Its fitted with the recommended ZYX-S2 gyro and Admiral 6S 1100mAHr battery. The only mod I made was to replace the tail servo with a KST-DS215 (but the stock one may have worked Ok - I didn't actually try it.) Regarding the tail setup, I simply started off with a HH gain of +30 (as viewed in the SETUP-MONITOR page of the ZYX Assistant software) and this setting worked (and is still working) just fine thank-you-very-much. I have not yet bothered to set up rate mode. Note that on a Tx with values ranging from 0-100 rather than -100 to +100, the equivalent CH5 gain value would be 65 (which would show as +30 in the software MONITOR). I also setup the linkages pretty much the same as James showed in his video - so that the servo arm was 90 in the middle of the usable range with the Tx sending out zero on the rudder channel. I haven't bothered measuring the tail pitch angle at zero, but it does have a bit of positive angle. I did move the tail servo ball in to 8mm from the arm center (stock was too far out at 12mm).

                      Bottom line - the ZYX is working very well so far.
                      Thanks again MotionRC!

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                      • Thank you for your excellent information and feedback ridgerunner! You and F106DeltaDart have really been helpful for others in these threads. Bravo Zulu! Well done! :Cool:
                        My YouTube RC videos:
                        https://www.youtube.com/@toddbreda

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                        • Curious where to mount FBL controller on the mechanics and wondering what others are doing.

                          1. Carbon tray under the main battery? With the mechanics out of the fuselage, and sitting on a table, this plate doesn't look flat (perpendicular to main shaft)
                          2. Bottom plate aft of the motor wires?
                          3. Middle shelf underneath where the boom enters the frame?

                          Also, did anyone rotate the tail servo mount (two clamps that attach to the boom) to get a straighter shot of the tail linkage? Seems like it would be better to have that rod with less of a bend in it. Just don't know if it will be a problem going back into the fuselage.

                          Thanks

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                          • I purchased the Huey with the ZYX system. I have looked through the above discussion and the video's. Could someone post pictures of the preferred location for mounting the receiver and gyro? The set up video's above show the receiver and gyro located at the rear of the the heli frame (they're using the HK450GT). I have a TREX 450 SE with flybar-less system and gyro and receiver are located in the rear to get away from motor and esc interference. Only way I see to do this on the Huey is to remove the chassis from the body. Also, I'd like to use the new Spektrum AR620 sport receiver, anybody know if this will work or will the graphite chassis cause interference ( I have not tried it on the Trex). I like these receivers and are using them in my planes (jets, propped, nitro and electric) and have not had an issue. Appreciate any assistance.

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                            • If you are able to take the frame off from the shell it would be much better to install the gyro right underneath on the battery Tray. I am using the Spektrum AR620 on this model shown and perfectly works fine.

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                              • This is also the Rotorscale 450 A-109 Frame set. I normally test fly my helis as pod and boom to dial in my controls whether small or large helis.
                                I have the tail rudder set at 0 pitch offset / neutral with 57.5% gain setting (HH Mode) on my Tarot gyro. Bring in the steel ball on the rudder servo arm closest to the center which will eliminate Tail wags.

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                                • Do I detect a tip-over at the end there? ;)

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                                  • Originally posted by eawings View Post
                                    If you are able to take the frame off from the shell it would be much better to install the gyro right underneath on the battery Tray. I am using the Spektrum AR620 on this model shown and perfectly works fine.
                                    Hi eawings,

                                    From your pics:
                                    1. It looks like the gyro is mounted on the bottom plate towards the tail of the heli. Your esc is right underneath the battery tray in front.
                                    2. Your tail control rod run to the servo looks a lot straighter than mine was out of the box for my huey. Did you remove one of the nylon tie wraps?
                                    3. I also moved in the ball from the stock position (3rd hole furthest away from servo screw). Right now it's in the middle position. I may try to move it to the innermost position as I'm still getting a steady and slight tail wag in hover with tail gains lowered all the way.

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                                    • Thanks to all for the information and photos.

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                                        Tried to move the tail servo ball inward but with the ball link on, it would hit the top of the servo case. The ball is mounted on the 'underside' of the servo arm.
                                        So back to the middle hole position. From arm center, the hole distances are about 7, 10, and 13mm going from innermost to outermost.
                                        As received, the ball had been mounted on the outermost hole in my model.

                                        I also attach a picture of what the tail control rod and tube look like. It runs along boom and then bends out towards the servo ball. Not as smooth and friction free as a straight shot run would be.
                                        Attached Files

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                                        • Can you not loosen the mounting and swing the servo round into a position where the ball is more in line with the cable run? Not sure if it will make that much difference to the geometry, but might be worth a try in order to reduce friction/bending moment.

                                          Fuselage fit permitting, of course.

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