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H Plus Retracting Landing Gear Mystery / Solution

DCH

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I turned on my H Plus for the first time the other day to calibrate the compass, but before committing to the calibration I decided so see how the gimbal reacted to being upside down. As soon as I flipped it over the landing gear retracted. "What the!" Then I couldn't figure out how to bring them up again, another "What the!".
I am very familiar with how to retract and lower the gear on the non-flying H480 for packing, but for some reason it wasn't working the same. Not sure how, but after flipping out and flipping the Plus over I got them down again and went on with the calibration.

I was grounded by rain today so I decided to get to the bottom of it. I took the camera off for the tests to save it the unnecessary workout. Here's what I found out.

First how to lower the gear once they have retracted in a non-flight situation. This is the simpler half of the subject so let's start there.
Like the H480, lowering the gear does not require the Controller, however the procedure is different. The H480 will immediately lower the gear as soon as the power button is pressed. With the Plus you must power it on first while holding it upright, then as soon as the LEDs stabilize after the boot, invert the Plus and within a second the gear will lower. As soon as they start to move you can return the Plus to its upright position while they are lowering. Basically the Plus needs to be upside down for both lowering and raising. I have repeated this process many many times, with and without the Controller on, and it works consistently every time.

Raising the gear in a non-flight situation is another subject altogether, here I cannot produce consistent results. It is as if there is a glitch or bug in the firmware. I am speaking in terms of Power Cycles "PC" here. In any given PC that raising the gear is successful, the results are very consistent and repeatable. That being when the Plus is inverted you can retract the gear with the switch, just like the H480. It does not matter when you flip the switch, it can already be in the "UP" position and as soon as you flip it over the gear go up.

This is something that can go unnoticed since the gear won't raise after power up if the switch is "UP" before the motors are armed and you are airborne, then you must cycle the switch before they will retract. This might be why many of you have experienced this "Involuntary" raising when inverting it. I can't rule this out in my initial experience, I wasn't going to fly it so I was not paying attention to the switch. Furthermore at no point in the testing was I ever able to get the gear to raise "involuntarily" upon inverting it, the switch HAD to already be in the "UP" position.

The problem with activating this function is not every PC is successful, and those that are, aren't consistent with each other. It seems to be a mater of timing, how long the Plus needs to be powered stationary up before inverting it to get the gear to operate. This can be anywhere from 20 seconds to 2 minutes or more -if at all. Not practical for those of us who pack it with the gear up. 20 seconds is OK, but two minutes is too long.

I ran more PCs than I kept track of but easily more than 30 (it rained all day!). At least 80% were successful, but the time it took to activate varied greatly. I had a string of 6 successful PCs in a row that took 20 seconds, I thought I had it figured out, but then went thru 6 unsuccessful PCs in a row where I gave up after 3~4 minutes -after that there no point in waiting. I even tried powering it up then inverted it right away and waited for them to retract, never happened. So at the end of a rigorous day of testing, I have come to the conclusion that there must be a bug causing this timing inconsistency.

I encourage anyone to try duplicating this with their Plus. No worries now because I am confident I have solved the "Lowering" side of the issue. The raising problem might be solved in FW versions newer than mine. If so I will upgrade to any firmware that restores this functionality. Anyone willing to explore this with me?

My Firmware is 20180906
 
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CraigCam

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So that happened to me on my first compass calibration post this last update. I turned it upside down old school and hit the switch to lower. For sure I’ll make sure the switch is down before lifting the Plus next time.
 
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Yup, the copter knows not to move the landing gear if it's on the ground. On the other hand, a test protocol is implemented, where the landing gear can become active on the ground, IF the copter is flipped upside down.

When it is upside down, the copter will start reacting to the position of the switch, which, in OP's case, must have been in "up" position.
 

CraigCam

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It’s actually different then the 480 though. Those gear won’t move unless flipped over where the Plus raised them when I picked it up for calibration before any turning. That’s what surprised me.
 

DCH

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I have been working on the H Plus landing gear mystery, both the cause and solution for "Involuntary retraction" as well as the intentional retracting for testing, service, or packing flat on a conventional backpack. Since I am one who often packs it flat on my daypack, I needed to find out how to reliably accomplish this like I have been doing with the H480. The procedure is similar, yet must be executed differently.

I think I have come up with the procedure that Yuneec should have included in the User Manual. However before posting it as a "How To", or suggesting it be included in the revised H Plus manual, I would like to see if others with an H Plus have success executing this mysterious hidden service feature. @Ty Pilot volunteered to be my first guinea pig and reported success. Are there any other guinea pigs out there willing to make history with me and give this a try? PLEASE speak up! I'm interested to see if it works with all Firmware versions.

~~~~~~~~~~~
To retract the Landing Gear for service, testing, or backpacking:
1) Power up the ST16S and allow it to boot up.
2) Power up the Plus and wait until the camera image appears on the screen.
3) Place the Landing Gear Switch to the 'retract' position.
4) Invert the Plus until the Landing Gear begin to retract, then right it again until they are fully retracted.
At this point you may now power off the Plus and ST16S, or jump to step 2b below to extend the Landing Gear again.

To Extend the Landing Gear:
1) Power on the Plus and wait until the LEDs stabilize usually 2~3 seconds. The ST16S and Camera are not required.
2a) If the ST16S is off or out of range, after the 2~3 second wait simply invert the Plus until the landing Gear begin to extend, then you may right it again while they extend.
2b) If the ST16S is on, you must first place the Landing Gear Switch in the 'extend' position and then invert the Plus until the Gear begin to extend, you may then right the Plus again while they fully extend. You do not need to wait for the Camera image to appear when extending the Landing Gear, as the C23 does not need to be mounted to extend them -only to retract them.

In summary, the function only works with the Plus upside down, but it must always be initiated right side up.
Retracting requires a link to the ST16S and C23.
Extending is semi automatic and only requires a battery with enough charge to power up and operate the servos.

A note on inverting. It does not seem to matter which direction the Plus is inverted, on mine it seems easier on the gimbal to invert the Plus in a nose-down direction. This results in less gimbal chatter. It's hardly important since it is only inverted for a moment.
 

Docdor

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Just got my H+ a couple days ago and have yet to fly it due to the wind so i decided to try your suggestion. IT WORKS! Thanks for the tip. Guess my only question is.. how did you think of that?
 

DCH

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Just got my H+ a couple days ago and have yet to fly it due to the wind so i decided to try your suggestion. IT WORKS! Thanks for the tip. Guess my only question is.. how did you think of that?
I didn't actually think of it like you might imagine. Like several others with a new Plus, mine seemed to automatically retract the the Gear the first time I flipped it over for a Compass calibration. Then like the others, I couldn't figure out how to extend them again. I wasn't sure what I did but they eventually extended. So Unlike the others, I decided to figure out the how and why of this new mystery for Plus owners.
 
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I have been getting a retract issue just today. Both legs go up but only the left leg comes down, I flip the switch a few times then both come down. Hope this is just a dirty contact.
 

DCH

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I have been getting a retract issue just today. Both legs go up but only the left leg comes down, I flip the switch a few times then both come down. Hope this is just a dirty contact.
This is a big red flag that I doubt has anything to do with the procedure above. A potentially intermittent gear servo is NOT something you want to have when it comes time to land.

The switch can't be the problem if only one gear servo is working. The switch is a single pole single throw (SPST), meaning it has only one set of contacts, and is either on or off. The switch only initiates the signal that the transmitter sends to the aircraft's receiver. That signal is sent to the servo board that actuates the two servos simultaneously. If only one servo is working intermittently, it has to be the servo itself, the servo board, one of the cable connections in between, or the slide-in contacts that mate with the servo. I would remove the offending servo and inspect the contacts, and clean them if necessary. Then go back and use the test procedure to test them several times. If you still get intermittent actuation, then further troubleshooting is needed.
 
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This is a big red flag that I doubt has anything to do with the procedure above. A potentially intermittent gear servo is NOT something you want to have when it comes time to land.

The switch can't be the problem if only one gear servo is working. The switch is a single pole single throw (SPST), meaning it has only one set of contacts, and is either on or off. The switch only initiates the signal that the transmitter sends to the aircraft's receiver. That signal is sent to the servo board that actuates the two servos simultaneously. If only one servo is working intermittently, it has to be the servo itself, the servo board, one of the cable connections in between, or the slide-in contacts that mate with the servo. I would remove the offending servo and inspect the contacts, and clean them if necessary. Then go back and use the test procedure to test them several times. If you still get intermittent actuation, then further troubleshooting is needed.
But the switch does put power to the servo on and off which is starting to tell me a loose connection. I just tried it at low hover and it worked 9 out of 10 times. I hand catch so even if only one comes down I can at lease grap it safe.
 

DCH

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But the switch does put power to the servo on and off which is starting to tell me a loose connection. I just tried it at low hover and it worked 9 out of 10 times. I hand catch so even if only one comes down I can at lease grap it safe.
Yep, you're on the right track, the transmitter side is doing its job, it has to be something in the aircraft.

I was going to suggest that you learn the hand catch, but sounds like you have that covered. :cool:

At least now you have a quick and simple test procedure you can use inside when you troubleshoot this issue, ...without blowing the tablecloth off the kitchen table!
 

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