Is this normal behavior from G-SPD?

Flyinpapa · Aug 7, 2022

Hey guys, lots of hours and good people along the way of fixing papa's drone.

Issues known when I got the rig from Mom:

1. Both batteries he had for it (Yuneec Originals) were swollen to a level that made insertion and removal from the drone complicated to say the least. Nothing was broken but they weren't happy in there and beyond first initial testing (10 mins or so) weren't used again.

2. CGO3+ is completely unresponsive. No power, no lights, just dead. It was more or less intact but bent up kinda, and just not sitting right. Noticed it looked like it had been worked on already, screws over tight and flexing plastic, covers not fit properly.

3. No GPS on a day with clear sky's, mostly full view of the sky...well ok, there's a tree...but should get something at least, right? ST 16 had connection to the drone, I could arm the motors (Props removed) in Angle mode, they would all spin seemingly how I would imagine they should, no 5 motor type errors. Had voltage of the Typhoon on the ST16, no GPS/SAT/POS/ALT/G-SPD...can't remember if it had distance.

So that's what I observed. So I got to doing research, ordered two batteries and a replacement GPS board. Come to find out the one in the drone was pretty badly damaged when I inspected it.

Swapped it and was going to say repair complete in all areas, and came across my G-SPD fluctuating while grounded. Here's a link to the video.

Right now I'm chalking it up to being in my backyard, with a tree somewhat overhead. I wondered if you guys could give me your opinion and any other ways I can test this puppy before I put on the props and take off the leash? I'm anxious to fly it, but this isn't the area for it and it's a little intimidating.

Also, what Mode type do you guys use? Mine was set at Mode 2, but I'm not sure if that's the default or because dad was a southpaw. Any flight training videos I've seen don't really address this. I mean specifically the ST16 settings for ELE/RUD THR/AIL...I may have some of those letters mixed up.

I've included some crash gore of the condition when I got it and some observations of removed parts, for your enjoyment. I don't have a dog or cat, otherwise I'd post one of those

Thanks for reading, can't wait to hear from y'all!

-JJ

h-elsner · Aug 8, 2022

Flyinpapa said:
Swapped it and was going to say repair complete in all areas, and came across my G-SPD fluctuating while grounded.

The short answer is yes, that's normal.

The long answer:
Groundspeed (G-SPD) is not really groundspeed. ST16 computes it from Vx, Vy and Vz, the speed in all 3 axis. Values come from GPS and IMU and will computed by a complex SW part called Extenden Kalman Filter (an estimation theory).
Because sensors will deliver slightly different values from IMU and GPS the filter tries to find an estimation. GPS accuracy depends on different circumstances like number of sats, weather, position related to sats, reflexions and so on. It should be between 0.2m to 0.5m but fix will be accepted around 1m.
IMU values depends on chip temperature, vibrations and so on.
What we see is a fluctuation result of the different values. Additionally there are some spikes with 2m/s to 2.5m/s. I cannot explain that but I think this is caused bay SW. Something like some default values in case of missing data or something like that. This will also cause fluctuations when drone sits still.

However, nothing to worry about.

Flyinpapa said:
Also, what Mode type do you guys use?

I use Mode 2. Mode 2 is default for drones. Some people who have flown helicopters or fixed wings may accustomed other modes. ELE/RUD THR/AIL are names derived from fixed wing RC.
Elevation is what we for drones call Pitch - fly forward
Aileron is Roll - fly side ward
Rudder we call Yaw - rotate the drone
Throttle depends on flight mode (not the RC mode above), for the flight modes Typhoon H offers it is always altitude - fly up/down. Flight modes are Smart, Angle and so on.
------------------------
There are two powerful tools for diagnostics: The GUI - a PC tool, drone conned to it via USB cable. It shows sensor data from IMU, GPS data, serial number...

Second: The flight logs stored on ST16. Flight logs contain a lot of data received from the drone and sent by ST16.

In case of problems people here will ask for flight logs.

For the ST16 the HW - monitor is important. To check your sticks should be a part of the pre-flight check.

In case of problem we have also output monitor which shows what is really going out.

I hope that helps.

be HE

jannislh · Aug 9, 2022

I use Mode 2. Mode 2 is default for drones. Some people who have flown helicopters or fixed wings may accustomed other modes.

Mode 1 and 3 (gas on the right side) are great if you have a plane which has to be thrown on takeoff. Unless you are left handed you will usually throw it with your right hand while your left hand is on the remote. When the gas is on the right side you will always have control over the important axis. On drones and helicopters it does not really matter. Mode 2 is the most one common but use whatever feels best for you.

2. CGO3+ is completely unresponsive. No power, no lights, just dead. It was more or less intact but bent up kinda, and just not sitting right. Noticed it looked like it had been worked on already, screws over tight and flexing plastic, covers not fit properly.

Seeing you images this is not a big surprise. All the connectors for motor and/or angle sensors are ripped off. Even some pads are missing. This will be fairly hard to repair. Unfortunately it is impossible to swap out the gimbals main board since it requires a factory calibration. The software tool needed is not publicly available. As a result this will be a fairly hard repair or you will have to swap out the entire camera.

In terms of the G-SPD I would also consider it to be normal. Especially when having a weak signal like under trees the ground speed might jump up and down a little. Nothing to worry about so far.

Flyinpapa · Aug 9, 2022

What an amazing set of replies! Quick and very informative, exactly what I was looking for to test before the real flight (finding a good area near my house still). This is probably why dad bought the Yuneec in the first place, I wonder if he had an account here.

To add to the repair side of things, i ended up sourcing a very lightly used cgo3+ on eBay. I figured the repair of that camera board was going to be beyond what i want to put money in. Who knows what condition the encoders and whatnot are in, the board was enough to call it spare parts.

Thank you so much. I'm gonna get out the ol field laptop and run some more tests, maybe hover it.

jannislh · Aug 10, 2022

Flyinpapa said:
What an amazing set of replies! Quick and very informative, exactly what I was looking for to test before the real flight (finding a good area near my house still). This is probably why dad bought the Yuneec in the first place, I wonder if he had an account here.

To add to the repair side of things, i ended up sourcing a very lightly used cgo3+ on eBay. I figured the repair of that camera board was going to be beyond what i want to put money in. Who knows what condition the encoders and whatnot are in, the board was enough to call it spare parts.

Thank you so much. I'm gonna get out the ol field laptop and run some more tests, maybe hover it.

Good to hear that you found a new camera for your bird. Nevertheless I would not mount it for the first flight since they are the most fragile part of the drone and usually the thirst thing to hit the ground. The airframe on the other hand is quiet robust and also very easy to repair. Without the camera the risk of a severe damage is fairly low. I would mount it as soon as your are confident that everything is working fine.

I also recommend to check the propellers for any damage and if they are marked with a Yuneec stamp. From my experience after market propellers are horrible. I had a total of four aftermarket propellers breaking without any apparent reason. In two cases I was able to land safely in five rotor mode but unfortunately the third incident resulted in a crash since both of the rear rotors broke at the same time. I assume that one propeller broke and hit the other one destroying it too.

Flyinpapa · Aug 11, 2022

After finally gaining some confidence in how to handle a drone, I decided to take it for a spin. With the camera removed, I did preflight checks, made sure I didn't have any aftermarket props

then I did a few quick hover and landings. Next took it up about 50 feet then smoothly back down. Then up to about 175 feet and back down. Everything went great except the landing skids didn't go up when I set the ST16 switch to up, so...something to look into before the next flight up. Feeling better about flying it, even after just a few tries, this thing is a dream in flight.

jannislh · Aug 11, 2022

Everything went great except the landing skids didn't go up when I set the ST16 switch to up, so...something to look into before the next flight up.

That is a fairly common issue on the Typhoon H series (all share the same mechanism). The endpoints are determined by the current flow. Therefore it might misidentify a mechanism which is harder to move than usual as one which already reached the endpoint. After a crash this might be caused by a bend lead screw. In many cases it is luckily only related to some dirt which can be removed.

You can also test the mechanism if you turn on everything as usual but than place the Typhoon H upside down (without props) and toggle the switch. Sometimes jiggling around its legs helps to unlock the mechanism and make it work again.

If they still do not work they can be removed very easily just by removing the two screws securing each one in place. If you have some kind of 5-6V Battery on hand you can also connect it directly to the contact plates. If I remember correctly the middle contact is not connected in any way while the outer ones are directly connected to an ordinary DC motor. Therefore you cannot do any harm to it as long as you are using a suitable voltage and do not connect it for too long if nothing is moving. If it does not move or it seems locked just reverse the polarity. Maybe wait a few seconds in order to let it cool down so you do not risk burning it.

In case still nothing moved you can open the mechanism and see if anything is damaged. Over there you will find a very good image of the mechanism inside: https://yuneec-forum.com/attachments/yuntyh131_broken-jpg.8897/

Like I said it is very common for the lead screw to bend in case of an accident. Furthermore and especially in older iterations (there are several version out there) the plastic housing tends to crack at the end of the lead screw which is away from the motor.

If everything looks fine you can remove the lead screw and clean it using isopropyl alcohol. Afterwards you can lubricate it with a very small (!) amount of grease. Too much will attract dirt. Do not lubricate the gears of the motor since everything will fly away anyway. In the same step you can also check if the motor itself is turning with everything else removed. If it does I would be surprised if it still does not move after reassembly. When reassembling it take care to mount the thrust bearings the same way you disassembled them since they are directional!

h-elsner · Aug 11, 2022

If it sounds like it is running out of round, the drive shaft could be bent. This sometimes happens after hard landing. I've had this happen and sometimes the landing legs worked and sometimes they didn't.
I could repair it.

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