Hi guys, I just received my first drone, a GEPRC Rocket Plus and I managed to crash it during my first flight, which was... hem... indoors. Yes I know... 

It landed upside down on a carpet and I disarmed it immediately. Then I wanted to try the FLIP function and I armed it again but immediately one of the props hit the carpet and incredibly I broke not only the prop (understandable), the prop guard (ok, fine) but also the 4 screws holding the engine were pulled out of the thread.
I attempted a restart after changing prop and prop guard but the engine would go on and off, so I switched off and accepted the reality. I have damaged my first drone 2 minutes into the first flight!

After some investigation and pushed by @SnowLeopardFPV to get my hands dirty (thanks!), I ordered some soldering and repair tools. In the meantime I opened up the heat shrink and found this:



It looks like two of the three wires detached, but not at the soldering point, on the engine winding itself...

I assume that is not good news??!

That's broken off into the windings. You're not going to repair that easily, if at all. That probably needs a re-wind of the motor but it's not an easy task. It will be easier and less effort to just get a new motor.

(07-Mar-2021, 07:52 PM)SnowLeopardFPV Wrote: That's broken off into the windings. You're not going to repair that easily, if at all. That probably needs a re-wind of the motor but it's not an easy task. It will be easier and less effort to just get a new motor.

Yeah, I had the feeling it was bad. I ordered the motor and will write back when it arrives and I’m ready for soldering.
Thanks

It looks liek the motor mount holes were actually stripped. I was gonna say get better screws, but if it's the motor mount that stripped then that doesn't speak well to those motors.

What type of motors are those exactly?

(08-Mar-2021, 10:38 AM)bLoWsMokE Wrote: It looks liek the motor mount holes were actually stripped. I was gonna say get better screws, but if it's the motor mount that stripped then that doesn't speak well to those motors.

What type of motors are those exactly?

GEPRC GR120.
I'm wondering as well how the heck the prop managed to touch the carpet considering there are prop guards.
And how in the name of the God of quads this caused the prop to brake itself, the guard and pull out 4 screws from the motor.
Finally, have enough energy to twist the motors wiring enough to brake two of them....
I really wonder how is this possible

I'm guessing the prop guard was probably partially fractured from the first crash and then it failed completely during the turtle-mode try. I have to say that initially I loved those 1204 5000kv motors. But I've now had two of them fail on my Rocket. One because of some debris or something inside that makes it sort of "grind" when turned by hand. I had a second one fail a few days ago. I don't know why it failed but it got really hot and I could smell an electrical type of burn. So I'm replacing all of them with some Xing 1303's I have and we'll see how the Rocket flies with them.

Guys, while I wait for my soldering gear to arrive, I removed the top part of the carbon frame (which has the DJI unit attached), and this is how it looks.



Now my question is, is that enough room to solder the new engine on the FC or I have to completely remove the Air Unit and the FC from the bottom of the frame?

Sorry it will sound silly to you experts but I have this doubt...

That's enough room. I would unplug the cable from the back of the Air Unit which will allow you to move it further out of the way. It will still be tethered to the quad by the camera cable but that has enough length on it to allow you to set the Air Unit to the side away from the quad for more working space inside the body of the frame.

(12-Mar-2021, 02:13 PM)SnowLeopardFPV Wrote: That's enough room. I would unplug the cable from the back of the Air Unit which will allow you to move it further out of the way. It will still be tethered to the quad by the camera cable but that has enough length on it to allow you to set the Air Unit to the side away from the quad for more working space inside the body of the frame.

Thanks SnowL, I did that and I also unscrewed the camera from the frame so it looks much more roomy now! Thanks.

(08-Mar-2021, 07:10 PM)doraymon Wrote: GEPRC GR120.
I'm wondering as well how the heck the prop managed to touch the carpet considering there are prop guards.
And how in the name of the God of quads this caused the prop to brake itself, the guard and pull out 4 screws from the motor.
Finally, have enough energy to twist the motors wiring enough to brake two of them....
I really wonder how is this possible

Oh this has happened to me before on a 3 inch.... it's not that impossible, and it happens quick. I'm thinking that the prop could have been stuck on the prop guard when you tried turtle mode....

This exact thing happened. a motor was loose so fell out of the air and i didn't know, so I did turtle mode and it ripped the screws out it ripped the threading off it ripped the propeller to shi^t and it ripped the motor windings out on a brand new motor.... all from a very quick blip in turtle mode.

First soldering done and I'm back in the air!!
I feel excited like a teenager lol.
I have to thank @SnowLeopardFPV for pushing me to venture in the art of soldering.
The result looks like sh... but hey, it flies!! See the picture below.



What I found more difficult was:
1) Removing the existing solder from the board, despite using a desoldering wick and pump. What a pain!
2) I struggled a lot to get some kind of round and shiny solder ball. I guess I'm doing something wrong because every time instead of a round surface I got spikes...

Good work  

(18-Mar-2021, 01:38 PM)doraymon Wrote: 1) Removing the existing solder from the board, despite using a desoldering wick and pump. What a pain!

Add flux to the solder wick and it will help it do a much better job. Make sure you use a tip that has a small chisel end (flats) rather than a pointed tip, and apply a very small amount of solder to the tip, both of which will give better heat transfer.

(18-Mar-2021, 01:38 PM)doraymon Wrote: 2) I struggled a lot to get some kind of round and shiny solder ball. I guess I'm doing something wrong because every time instead of a round surface I got spikes...

That happens because all of the flux has burnt off and vaporised. Multicore solder has flux embedded into the solder but unless you are quick it will vaporise in an instant. The solution is to use additional flux (i.e. a flux pen or syringe) and apply a liberal amount of it to the solder joint area. When you then apply the soldering iron tip to the joint the flux will liquify and keep the area under a pool of flux leaving a shiny round joint. After you are done, use 99.9% Isopropyl alcohol and a Q-tip to clean of the flux to leave some nice shiny uncontaminated solder joints.

Great, understood thanks.
I bought some Rosin Paste Flux (Romeda), so no pen or syringe.
Is it ok if I use the tip of my tweezers to put some paste on the joints?

(18-Mar-2021, 02:16 PM)doraymon Wrote: I bought some Rosin Paste Flux (Romeda), so no pen or syringe.
Is it ok if I use the tip of my tweezers to put some paste on the joints?

Yes, it's fine to do that. I have a tub of flux rather than a syringe or a pen, and I use a small flat-headed screwdriver to blob and spread flux onto the joints.

(18-Mar-2021, 02:21 PM)SnowLeopardFPV Wrote: Yes, it's fine to do that. I have a tub of flux rather than a syringe or a pen, and I use a small flat-headed screwdriver to blob and spread flux onto the joints.

Thanks mate.

I will post again here at the next crash