Yesterday's incident- and prop changing tips

[vindibona1]

The oddest thing happened yesterday after I was finished flying and brought my Mini 3 home for a landing. The homepoint was a driveway with a "pebbled" surface where I have launched and landed many times. I'm not sure if I'd previously flown my Mini 3 from that spot, but I think once or twice. As I brought the Mini 3 in, it hovered above the driveway about a foot, but refused to land. I finally got it down to the ground but the motors wouldn't shut off, even as I pulled both sticks down and in for the emergency shut of move. I thought to take it up again and try once, more, possibly on the grass. As I pushed the left stick forward the Mini 3 didn't go up, but flipped over on its back, where the motors finally stopped, not without severely chipping one of the props. I'm glad that that's all the damage that was done.

It may be important to say that this was only the second time that I'd installed the "skid" type height extenders (can't call them "leg" extenders any more, can we?). Previously I'd been flying with the strap-on "spider legs" kind with its own legs (photos of each below). I learned a few things about changing props on the Mini 3 which I didn't need to consider with my Mini 1 or Mini 2. I want to share a few things with the forum to consider when changing props to make things easy when it comes to change props on the Mini 3

1) GET A *GOOD* SCREW DRIVER! The one that comes with the Mini 3 is a toy. I was glad I heeded another forum member's warning when he lamented stripping a screw head when changing props. I preemptively bought a good screw driver and lucky to be prepared. The factory installed props are REALLY REALLY tight. I don't know if I would have been able to loosen the screw on the prop that needed replacement without it. Even with the good screw driver it took a LOT of downward pressure to keep the driver seated in the screw slots. Screwdriver for Mini 3 screws

2) Have something handy to rest the arms on when removing or replaceing the screws. Perhaps DJI is using some sort of super-Loc-tite around the screws, but again, it required a ton of downward pressure both to remove the old screw and replace the new one. I used the case for my calipers. About 3/4" inch high or so.

3) Pre-emptively loosen the factory installed screws so it just breaks free and then retighten. Some of them were a bear to break free and I certainly don't want to wrestle with the screws out in the field, especially because the screws on the Mini 3 are tiny- smaller than the screws on the Minis 1 and 2.

4) Familiarize yourself with which props go on which arms. Y'all are probably smarter than me, but I was confused because when I looked at the prop facing up the wrong way the orange marking looked like I had the right prop, but it was wrong. I finally realized that there is a u-shaped mark under one set and none on the other. I think I got it right but haven't test flown my Mini 3 since replacing the props.

If there is anything to take away from these tips is that the factory installed propeller screws come super-tightly screwed in and it wasn't much easier putting a new screw back in. Having the right tools on hand when you need them can avoid a lot of aggrevation. The last thing I wanted was to deal with one or more stripped screw-head slots.

I bought both but from now on will be using the "spider legs" version rather than the "skid" version. I got them in gray, not orange.

 

[old man mavic]

@vindibona1 ,I would say that because of the pebbled surface,in the first instance, the sensors were getting conflicting images being bounced back from the many different angles of the pebbles
then when it did manage to land the drone did not feel stable enough to turn off the motors
it was not completely level at that point ,when you attempted to lift off again the IMU reacted by giving two of the motors additional rotation in order for the drone to be level and in that instant that's what flipped it over,the direction it flipped would have had a direct correlation, to the angle it was leaning at it did not know it was on the ground ,and just reacted as it would have done during flight ,
some good tips on prop changing ,the screws are indeed very small ,definitely a job for a well lit indoor area

 

[vindibona1]

@vindibona1 ,I would say that because of the pebbled surface,in the first instance, the sensors were getting conflicting images being bounced back from the many different angles of the pebbles
then when it did manage to land the drone did not feel stable enough to turn off the motors
it was not completely level at that point ,when you attempted to lift off again the IMU reacted by giving two of the motors additional rotation in order for the drone to be level and in that instant that's what flipped it over,the direction it flipped would have had a direct correlation, to the angle it was leaning at it did not know it was on the ground ,and just reacted as it would have done during flight ,
some good tips on prop changing ,the screws are indeed very small ,definitely a job for a well lit indoor area

I do believe it was a sensor problem. For the second time I experienced something like that when using the "skid" type height extender. It should not be blocking the sensors, but probably is in some way. On earlier flights, while it did land without a problem with this extender it came down pretty hard from about 3' up, something unexpected. I'm used to more of a buffered last few inches. In that case the skids provided some shock absorption, but it came down in sort of a splat. I'm not sure why this has become a problem. The sensors look unobstructed. Further investigation is in order.

As shown above, I also have the "spider legs" height extension as well and like it because it packs well, but takes a few seconds more to install and is a few grams heavier. I've had no issues with that one and am now going back to it. I hope to get out this afternoon for a few minutes to test for stability and landing.

In terms of prop installation tips, I hope I've help some members avoid frustration and aggrevation. In the earlier Mini iterations prop swapping was much less a wrestling match.

 

[Dale D]

The oddest thing happened yesterday after I was finished flying and brought my Mini 3 home for a landing. The homepoint was a driveway with a "pebbled" surface where I have launched and landed many times. I'm not sure if I'd previously flown my Mini 3 from that spot, but I think once or twice. As I brought the Mini 3 in, it hovered above the driveway about a foot, but refused to land. I finally got it down to the ground but the motors wouldn't shut off, even as I pulled both sticks down and in for the emergency shut of move. I thought to take it up again and try once, more, possibly on the grass. As I pushed the left stick forward the Mini 3 didn't go up, but flipped over on its back, where the motors finally stopped, not without severely chipping one of the props. I'm glad that that's all the damage that was done.

It may be important to say that this was only the second time that I'd installed the "skid" type height extenders (can't call them "leg" extenders any more, can we?). Previously I'd been flying with the strap-on "spider legs" kind with its own legs (photos of each below). I learned a few things about changing props on the Mini 3 which I didn't need to consider with my Mini 1 or Mini 2. I want to share a few things with the forum to consider when changing props to make things easy when it comes to change props on the Mini 3

1) GET A *GOOD* SCREW DRIVER! The one that comes with the Mini 3 is a toy. I was glad I heeded another forum member's warning when he lamented stripping a screw head when changing props. I preemptively bought a good screw driver and lucky to be prepared. The factory installed props are REALLY REALLY tight. I don't know if I would have been able to loosen the screw on the prop that needed replacement without it. Even with the good screw driver it took a LOT of downward pressure to keep the driver seated in the screw slots. Screwdriver for Mini 3 screws
View attachment 154815
2) Have something handy to rest the arms on when removing or replaceing the screws. Perhaps DJI is using some sort of super-Loc-tite around the screws, but again, it required a ton of downward pressure both to remove the old screw and replace the new one. I used the case for my calipers. About 3/4" inch high or so.

3) Pre-emptively loosen the factory installed screws so it just breaks free and then retighten. Some of them were a bear to break free and I certainly don't want to wrestle with the screws out in the field, especially because the screws on the Mini 3 are tiny- smaller than the screws on the Minis 1 and 2.

4) Familiarize yourself with which props go on which arms. Y'all are probably smarter than me, but I was confused because when I looked at the prop facing up the wrong way the orange marking looked like I had the right prop, but it was wrong. I finally realized that there is a u-shaped mark under one set and none on the other. I think I got it right but haven't test flown my Mini 3 since replacing the props.

If there is anything to take away from these tips is that the factory installed propeller screws come super-tightly screwed in and it wasn't much easier putting a new screw back in. Having the right tools on hand when you need them can avoid a lot of aggrevation. The last thing I wanted was to deal with one or more stripped screw-head slots.

I bought both but from now on will be using the "spider legs" version rather than the "skid" version. I got them in gray, not orange.

View attachment 154816View attachment 154817

I know really nothing about the electronic of these sensors but my intuition tells me that I would rather try to use an "H" type landing pad that the drone can easily recognize as a home point rather than a non-distinct surface such as a heterogeneous stone surface with no distinct markings.

I have never used leg extenders or other landing aids.

Dale

 

[jimlips]

Thanks for the info about getting a "real" screwdriver. I will do the same.

Learn to land the Mini 3 Pro in your hand. That is the exclusive way I land now with this aircraft, and never have a problem. I also feel very comfortable doing this more so with this drone than any other, probably because of its light weight. Just be sure and aim the craft away from you, keep your hand flat, palm up, also pointing away, and let it rest into your palm. Do NOT curve your fingers up to grab it. Just let it rest into your hand while you keep the left stick down until the motors shut off. The drone will "pull up" for a few seconds when it sees your hand, but as long as you hold the left stick down, it will eventually figure out you want to land and come down into your hand.

 

[Eagle Eye 62]

I too have seen some weird behavior when using the "skids" Pretty sure it does interfere with the downward sensors. I always try to use a landing pad whenever possible to prevent prop wash from kicking up dirt and small pebbles.

 

[RogerDH]

I know really nothing about the electronic of these sensors but my intuition tells me that I would rather try to use an "H" type landing pad that the drone can easily recognize as a home point rather than a non-distinct surface such as a heterogeneous stone surface with no distinct markings.

I have never used leg extenders or other landing aids.

Dale

The Mini series doesn't have the "precision landing" function that would visually recognize a landing pad -- it's just GPS. It does, however, use it's downward IR sensors to check for uneven ground that doesn't appear suitable for landing.

 

[vindibona1]

I know really nothing about the electronic of these sensors but my intuition tells me that I would rather try to use an "H" type landing pad that the drone can easily recognize as a home point rather than a non-distinct surface such as a heterogeneous stone surface with no distinct markings.

I have never used leg extenders or other landing aids.

Dale

I have a landing pad but have rarely used it. It's inconvenient in many locations and slows down the deployment. About the only time that I felt the necessity to use it is if I have to launch or land on grass or dusty surface. This Mini 3 is the only drone I've had that ever had a landing problem. The landing was on my daughter's driveway, from which I've flown many time, but only a couple with the Mini 3. I suspect it had to to with the height extender. I'd not had issues with the spider legs type before. I found a way to pack the skid type and thought it would save me a couple seconds in deployment because it just snaps on, rather than fastens with a band.

Had I been in a different situation I would have just pushed it up a few feet higher and hand catched it. But this time I had my 4 year old grandson between my legs, sitting on a step, as I've been teaching him to fly. He's starting to get it, but he's not ready to stand there on his own with the controller.

 

[vindibona1]

Update:
With the new prop installed I went out to do a test flight this afternoon. This time I used the spide-legs extension and my Mini 3 landed multiple times without incident as it is supposed to. It might be important to note that I launched an landed on a painted cement surface with no pattern whatsoever unlike the textured pebble surface of the driveway where the aforementioned incident occurred.

Bottom line: No more skid type height extender for me. It is obvious that somehow it is interfering with the downward looking sensors.

I will be interested if anyone else has had similar experiences with skid type extender?

 

[djwak59]

Thanks for the info about getting a "real" screwdriver. I will do the same.

Learn to land the Mini 3 Pro in your hand. That is the exclusive way I land now with this aircraft, and never have a problem. I also feel very comfortable doing this more so with this drone than any other, probably because of its light weight. Just be sure and aim the craft away from you, keep your hand flat, palm up, also pointing away, and let it rest into your palm. Do NOT curve your fingers up to grab it. Just let it rest into your hand while you keep the left stick down until the motors shut off. The drone will "pull up" for a few seconds when it sees your hand, but as long as you hold the left stick down, it will eventually figure out you want to land and come down into your hand.

IDK, just me, but from my early drone flying days, I’ve always heard not to launch or land a drone in your hand.
If you can do it, cool, but I still won’t.
Just my thoughts.

 

[old man mavic]

Hand launch /Land ,is purely a personal choice that we as flyers make for ourselves
DJI dont recommend it ,simply because of the risk of injury from fast spinning props,
if something goes wrong,i choose not to do it because of the medication i take
which decreases the coagulation of my blood .so getting an injury ,for me would not be a good thing ,especially if i was at some remote location

 

[vindibona1]

IDK, just me, but from my early drone flying days, I’ve always heard not to launch or land a drone in your hand.
If you can do it, cool, but I still won’t.
Just my thoughts.

I rarely do hand catches or launches for all the aforementioned reasons. Sometimes it is just necessary. I often launch from a narrow balcony on the 2nd floor and the hand catch is not a favorite thing to do. Because of the low ceiling and the railing it has to cross over on the balcony engaging the bottom sensors, I cannot allow it to ltry to land flat on my hand lest it rise up into the ceiling. So the only solid way to do a hand catch is to reach over the rail and use the "grip-it-and-flip-it" method. I don't like doing it that way, but I'm often left with little choice unless I want to land it in a nearby parking lot (where I will almost always set the home point) and then go run after it when it's finally on the ground.

 

[vindibona1]

UPDATE:
I was perplexed that I had landing issues with the "helo skid type" height extension where I had no issues with the "spider leg" one. Having experienced a "soft" crash landing and a subsequent failure to land on a textured surface (resulting in the drone flipping over) the only conclusion I could make was that the sensors were blocked somehow.

While the skid type extender is a little challenging to pack I liked the way it clipped on, rather than strap on, which requires more handling I thought that perhaps opening up that areas over the sensors might help. So that's what I did. And in my test flights, there were no issues, including landing on plain black, untextured asphalt.

While I could have done a cleaner job opening the holes with a dremel tool I was too lazy to take it out so I just whittled the holes larger with an exacto. While they still need sanding to smooth them (I guess I'll have to get the dremel out anyway) the opening seems to have done the job. While the holes for the sensors were generally in the right place, when mounted they didn't sit exactly symmetrically, but that's a moot point now.

 

[Torque]

The skid type leg extensions must be your problem.
I deploy and land all of my drones from my exposed aggregate concrete driveway and none of them has ever had an issue with the surface.
Rarely hand catch either, just not worth the small risk of an injury - I need my fingers to fully function 24/7!

 

[vindibona1]

The skid type leg extensions must be your problem.
I deploy and land all of my drones from my exposed aggregate concrete driveway and none of them has ever had an issue with the surface.
Rarely hand catch either, just not worth the small risk of an injury - I need my fingers to fully function 24/7!

Do you use extensions?
One of the reasons that extensions are almost an necessity for me is because more often than that I placed a strobe on the bottom of my drones. Additionally, should I have to land on the grass I prefer not to turn my drone into a Weedwhacker. Lastly, keeping the drone a bit off the ground helps keep bits of dust rocks and debris out of the propellers and motors.

 

[Torque]

Do you use extensions?
One of the reasons that extensions are almost an necessity for me is because more often than that I placed a strobe on the bottom of my drones. Additionally, should I have to land on the grass I prefer not to turn my drone into a Weedwhacker. Lastly, keeping the drone a bit off the ground helps keep bits of dust rocks and debris out of the propellers and motors.

Yes, I use the spider legs with almost every flight. I have an early review of them up on the forum from soon after they were released. I have never used the skid types on any of my drones. I have velcro mounted on the leg's straps to hold my strobes as well.

 

[vindibona1]

Yes, I use the spider legs with almost every flight. I have an early review of them up on the forum from soon after they were released. I have never used the skid types on any of my drones. I have velcro mounted on the leg's straps to hold my strobes as well.

I like the spider legs better, but the installation of the skids can be a bit quicker and a few grams light. I prefer not to have to fiddle with the band. I've managed to find a way to pack both so I have a choice. I think the skids would be better on grass.

 

[hjones62]

IMO, I'd say DJI dropped the ball with the low profile landing gear on the Mini 3 Pro. Depending where you are landing, props come quite close to the ground as you land. Buying extenders is not for everyone. I do understand it's the Mini but landing gear could've been extended a tad more to rise the body of the drone from the ground.

 

[SkiProiii]

If I’m going to land on the ground, I’ve always used a pad - just keeps debris from kicking up into the props, body and motors on take off and landing and providing a visual & flat base on grass, etc. It’s a “best practice” more than necessity.

Hand launch: If new to the Mini 3 Pro and coming from Mini 2, the 3 will not take off with the motors idling and “bumping up” the drone like the 2 does. It will just fall. It’s a feature I miss!

Hand launch/recovery- there is always an increased risk of these manoeuvres around blades that will cut you. I’ve done it enough that I’m comfortable using it for all flights and keeps away from debris too. My experience/ tips - have a lanyard for stability of the controller. Practice with low wind to get comfortable with how the drone behaves, and always have the drone downwind from you on take off and landing. I pinch the drone body with thumb and two fingers, start the motors and release as I push the left stick up. Recovery - I hover drone just above my head downwind a meter with camera towards me. Extend my hand under drone walking towards it, and slowly decent until landing initiated by drone. I pinch the drone body with my thumb and two fingers so it can’t jerk as the motors power down and wind doesn’t flip off my hand.

It is a preference that I am comfortable with but I’m doing so with lots of practice and knowing it comes with much higher risk of injury to me. There is little risk using a pad to get cut or hit vs hand methods, so I fully agree with the other comments as a best practice for safety, it’s not hand launch and recovery!

 

[Lazerbrains]

Just happened to see this on Amazon today. Interesting idea for safer hand launch/recovery?

Mini 3 Hand Guard