First Crash

[Dependabletv]

Hi,
I've just had my first crash experience and it was utterly terrifying. DJI550 with Naza. I'd just completed 2 flights without a problem. I changed the battery and took off again. The machine seemed to be yawing a little without intent so I brought it back down. Everything looked OK so I gingerly took off again. This time it yawed in the same direction but was heading towards a wall. I couldn't add enough correction to the yaw so had to add power to clear the wall. As I did this the yaw seemed to get worse. I tried desperately to correct it, flicked to the home orientation mode and it really started to fly away from me then (pointing to a GPS issue) I managed to bring it roughly back in my direction but at quite a height. It then started "toilet bowling" before yawing so much it turned upside down and came down very hard into a hedge - X Factor style. Thankfully, nobody was near it and no physical damage seems to have been done. However, it was simply terrifying - especially as we've just ordered a bigger machine to put a very expensive camera on.

I know I had two flashing red GPS lights on take off but they had been on for the previous two flights and, as it's a calm day, I thought I could fly in attitude mode. Clearly I was wrong as I can only think it must be a GPS issue. Anyone any other ideas?

I'll test it tomorrow with no red lights! but will make sure I have plenty of open space around me. I wouldn't wish that experience on anybody
R

 

[ewr]

2 flashing red and I'm assuming a yellow if you took off in atti with 5 sats you are saying? If you were in atti no GPS mode I think the number of sats would have nothing to do with your issue, no? Why did you switch to a mode (HO) that relies even more heavily on the compass/gps if you knew it was acting funny to begin with? (as you saw the result of it flying away). I'm still a NAZA noob so if those questions make no sense, my apologies.

I hate the "kind of in control" crashes...gets your heart going! The motor failure or total signal loss with no RTH/ALH failure crashes are kind of calm...it just drops from the sky and there isn't crap you can do about it but watch it tank into the ground, so I find those "better" than the ones where your mind is racing to correct with the radio but it tanks into the ground anyways...I hate the fly aways because you can't see where/who/what it's going to hit until you get to the crash site so those are really heart pumping also....glad to know there was no damage and just took out a hedge! I was flying a small 400 quad FPV from inside my house so I had NO LOS, that I took up too far into a wind gust and it blew it about 1/2 mile away in what seemed like a few seconds, right over a baseball game in action, and once I got it stabilized and out of that wind shelf the battery started to die! so once again I'm descending over this baseball game with a wall of 100' trees between my landing area and this baseball field...did NOT want to land in the field and stop the game and look like an idiot so I gave it 100% throttle and hoped for the best....made it over the trees but the motors cut out just as I was about to descend...75' fall ended that quad but I was just happy to have it crash in my own yard

 

[Dewster]

Crashes suck. They suck even more when you have numerous successful flights under your belt. I had a flat Hexa with gimbal, FPV equipment etc. reading and hearing about other flyers changing over to carbon fiber props lead me to believe that this was a better choice. I chose the wrong brand of props. My flat Hexa crashed in less than five minutes of total flight time with the new props. I heard a snap, which was followed by a flurry of activity as my WKM tried to stabilize the craft, and watched what was a reliable ship fall straight to the ground. Everything was busted except for my WKM, four motors, and five ESCs. My 6000 mah lipo was punctured and felt like I was standing next to an oven when I unplugged it from my twitching Hexa.

I agree that I would rather see my craft drop vs. having a wild semi controllable object limping in space. Every now and then I'll read about fly aways. Its got to be worse than seeing your craft drop from the sky.

 

[kloner]

i'd expect this to have come from an unbalanced prop that went into a major vibration or a motor bearing that was leaving left....

 

[Dependabletv]

When I got the machine back last night I spun it up on the ground and all appeared to be OK with each motor responding as I'd expect. However, there was some very minor prop damage from the impact so I replaced all the props this morning and have just carried out 4 totally normal flights.

According to the Naza GPS manual, 2 flashing reds means it has 5 GPS satellites and if it loses all satellites it is supposed to switch to attitude mode. I've also seen lots of other machines on YouTube this morning exhibiting very similar behavior before crashing. I wish I found a fault as I don't feel like I have fixed anything so I presume it could happen again at any time. I certainly won't be taking off with red lights flashing in future though.

All very alarming

 

[Zeke]

A very similar situation happened to me, except I was a little stupid about it (I do have to say). It was about midnight and I'm outside in a somewhat well lit open area, and a few of my buddies I work with (military) were outside drinkin' and smoking. One of them had seen me flying the quad before so he asked if I could bring it over and show the rest of the guys. Well that was fine by me, I wasn't letting them fly it. So I setup about 15 yards from where they're standing, take off and just kinda cruise around a bit in Atti. They asked me to take it higher and clear treetop level, which I shouldn't have listened to but I felt it was light enough I could manage to navigate just fine with. Heres where my real problems started... I switched it into GPS mode, turned around and gave a thumbs up at my amazed drunk buddies, turn back looking up at the Quad and noticed it drifting at a quick rate towards a tree. Oh crap. In my haste to bring it back, I bumped one of the IOC's and thats when it went the wrong way, and hit a tree branch and got stuck, about 60 feet up in the tree. Needless to say we spent the next 2 hours throwing two footballs at the quad, and they managed to catch it on the way down, while amazingly nothing broke.

3 lessons learned:
Don't try to impress drunk people.
Don't use GPS unless you've already verified all you're sats.
Don't think about flying near trees you can't climb or don't want to leave your Multirotor in.

 

[ewr]

I thought JUST 2 red means 5 says in manual mode? Then 2 red with 1 yellow is 5 sats atti mode, and 2 red 1 green is 5 sats attiGPS mode. I still think switching to HO was not smart since the yaw was uncontrollable and the compass was probably messing up, or maybe the naza was just angry about the V2 coming out..who knows! Maybe it was losing some sats but getting them back in time to not switch you to atti mode and was confused.

I too HATE when you have a crash like that with an intermittent issue and can't find the cause...every flight after that you always have it in the back of your mind....for me it almost ruins the experience sometimes esp if I'm flying FPV out of LOS I'm always worrying about it crashing in a bad spot more than I am enjoying the flight.....I usually rebuild or change out some components on those crafts to ease my mine even thought technically it's just as likely to crash as before lol. It seems with our MRs the data logging has been lagging behind all the "cool" features like RTH and IOC.....this is the reason I am using data logging ESC's on my new hex build....at least I can rule out the motors and ESCS after a crash that way. Good luck on your flights!

All very alarming[/QUOTE]

 

[Dependabletv]

When I say two red lights means 5 Satellites - that is irrespective of the mode it's in. You're quite correct about the green/amber and no light then indicating the mode. In my case it took off flashing 2 reds then green.

The whole experience does leave me with a whole load of questions. I know that a loss of satellites would affect the ability to return to home. Are there any circumstances in which they will affect the attitude of the machine. Something did. From what I've read today, losing GPS should not induce this kind of behavior - so it was something else. I just wish I knew what. It flew like a dream again today.

 

[SMP]

Had a GPS puck mounted backwards (my error) and made the craft virtually unflyable in Atti. Shouldn't have affected it but did... Tstrike had some great advice which I say to myself before every flight now, "Flip to manual and tons of throttle"

 

[Dependabletv]

I used the throttle plan to stop me hitting a wall but given that my machine then flipped, I fear more throttle would have been a very bad plan at that stage. I didn't flip to manual - that would have been next but it all happened so quickly it was unreal and I just didn't have time to react once I realised IOC was not working. I was struggling to control it but getting it back in the right direction slowly, I tried IOC and it headed away from me, manual would have been next but it then just flipped and headed for the ground. It was almost as if it was fighting my yaw command and when I had no more to input - it won

 

[ewr]

Had a GPS puck mounted backwards (my error) and made the craft virtually unflyable in Atti. Shouldn't have affected it but did... Tstrike had some great advice which I say to myself before every flight now, "Flip to manual and tons of throttle"

That's pretty odd...you'd think if GPS/Atti was OFF then it shouldn't listen to the GPS at all, right? Whats the point of being able to switch off GPS mode if your having an issue if it still uses the GPS in regular atti mode...maybe it uses the compass for something?

Sounds like you did what you could dtv....things do happen so fast with MRs compared to planes where you have a few seconds of glide time before needing to make a decision (obviously varies with altitude) or even heli's where you might be able to autorotate down....Usually before I maiden a new MR or fly a "questionable" setup I always have a little mental list of things to do if SHTF.....always seems like a fool proof plan until it happens and I don't even have time to get to #2 on the list before it's in the ground or a tree! Keep making flights and maybe even try to replicate everything you did on that flight and see if you can find the cause.

 

[Dewster]

I used the throttle plan to stop me hitting a wall but given that my machine then flipped, I fear more throttle would have been a very bad plan at that stage. I didn't flip to manual - that would have been next but it all happened so quickly it was unreal and I just didn't have time to react once I realised IOC was not working. I was struggling to control it but getting it back in the right direction slowly, I tried IOC and it headed away from me, manual would have been next but it then just flipped and headed for the ground. It was almost as if it was fighting my yaw command and when I had no more to input - it won

I know the feeling. When my prop broke the loss caused my craft to flip out. I knew instantly that it was doomed, especially when I heard the snap of a carbon fiber prop breaking. I spent an hour trekking through the woods looking for the wreckage. It left a nasty taste in my mouth when I knew there was nothing I could do.

 

[ewr]

Crashes suck. They suck even more when you have numerous successful flights under your belt. I had a flat Hexa with gimbal, FPV equipment etc. reading and hearing about other flyers changing over to carbon fiber props lead me to believe that this was a better choice. I chose the wrong brand of props. My flat Hexa crashed in less than five minutes of total flight time with the new props. I heard a snap, which was followed by a flurry of activity as my WKM tried to stabilize the craft, and watched what was a reliable ship fall straight to the ground. Everything was busted except for my WKM, four motors, and five ESCs. My 6000 mah lipo was punctured and felt like I was standing next to an oven when I unplugged it from my twitching Hexa.

I agree that I would rather see my craft drop vs. having a wild semi controllable object limping in space. Every now and then I'll read about fly aways. Its got to be worse than seeing your craft drop from the sky.

Not to derail this thread, but mind telling us which props NOT to buy so we know? lol I finally switched to CF props on my smallest quad (10x4.5) and holy crap what a difference...I went from stock plastic which were 12g and decent but snapped off like toothpicks upon even the lightest crash...then tried some cheapie amazon slow fly props that were only 8g but so flexible they just caused oscillations so bad they just broke off at the hub mid flight....then finally picked up these RCTimer props which are 10g, so 2g lighter than stock...and all I can say is wow....put them on my balancer and all are perfectly balanced, finish is great....so far I've crashed about 4 times lightly and twice hard...not one broke!

The hardest crash I was talking a very pretty lookyloo that walked up to me in my yard and I got a little fat fingered (as usual when I try and check out girls and fly at the same time) and switched to manual mode by accident...went to do a fast approach and land to "showboat" and it flipped 90 degrees and came down hard exactly on it's two front arms...best part was BOTH props were pointing towards the ground and they literally sunk down to the hub into the grass/dirt...leaving the quad awkwardly sticking up out of the ground! Pulled it out of the ground, re attached the battery that went flying...and it was up in the air again! The other hard crash was a ESC overheat at about 50' AGL....came down hard and broke one arm and a motor mount on a different arm, but again all props were fine!! I also was an idiot and flipped it on the concrete sidewalk (was testing out new rubber feet that I never have tried before...I'm used to it skating across hard surfaces but forgot the rubber would grab..oops!)..the noise CF props make when hitting concrete is, well, sad, for lack of a better term.....but all that happened was the very tips are a little frayed....put some clear nail polish on them and they are fine! Best part is including shipping they were only $5 more for a set of 8 props than the crappy plastic ones! Never flying anything but these again! Just my luck Dewster you're going to say the bad brand of props is the brand I'm using lol. I'm almost wondering if I'm just getting lucky with these, or are all CF props really this strong? For less than a dollar more each I don't know why everyone isn't using them!

 

[Dewster]

Not to derail this thread, but mind telling us which props NOT to buy so we know? lol I finally switched to CF props on my smallest quad (10x4.5) and holy crap what a difference...I went from stock plastic which were 12g and decent but snapped off like toothpicks upon even the lightest crash...then tried some cheapie amazon slow fly props that were only 8g but so flexible they just caused oscillations so bad they just broke off at the hub mid flight....then finally picked up these RCTimer props which are 10g, so 2g lighter than stock...and all I can say is wow....put them on my balancer and all are perfectly balanced, finish is great....so far I've crashed about 4 times lightly and twice hard...not one broke!

The hardest crash I was talking a very pretty lookyloo that walked up to me in my yard and I got a little fat fingered (as usual when I try and check out girls and fly at the same time) and switched to manual mode by accident...went to do a fast approach and land to "showboat" and it flipped 90 degrees and came down hard exactly on it's two front arms...best part was BOTH props were pointing towards the ground and they literally sunk down to the hub into the grass/dirt...leaving the quad awkwardly sticking up out of the ground! Pulled it out of the ground, re attached the battery that went flying...and it was up in the air again! The other hard crash was a ESC overheat at about 50' AGL....came down hard and broke one arm and a motor mount on a different arm, but again all props were fine!! I also was an idiot and flipped it on the concrete sidewalk (was testing out new rubber feet that I never have tried before...I'm used to it skating across hard surfaces but forgot the rubber would grab..oops!)..the noise CF props make when hitting concrete is, well, sad, for lack of a better term.....but all that happened was the very tips are a little frayed....put some clear nail polish on them and they are fine! Best part is including shipping they were only $5 more for a set of 8 props than the crappy plastic ones! Never flying anything but these again! Just my luck Dewster you're going to say the bad brand of props is the brand I'm using lol. I'm almost wondering if I'm just getting lucky with these, or are all CF props really this strong? For less than a dollar more each I don't know why everyone isn't using them!

I had Gemfan full carbon fiber props on my first flat Hexa. I had a lot of trouble free flights with my craft when I was using APC props. I read about CF props and bought the wrong pair. One of the props broke at the hub during flight. Everything else was history. You have to be careful when buying props. It's not enough to clone a prop by shape and material alone. I stay away from the carbon fiber props that look as if they were simply stuck/glued/attached to the hub. Just a hairline fracture is enough to send a blade off in space and your craft into the ground. The prop blades itself was barely damaged. You could see where it separated at the hub. Hold onto a brand that's reliable. Just know that quality control with any brand can go up and down.

I have APC props on reserve (they are noisy and dependable) and I use Graupner (good luck finding 'em) props on my current craft. I'm pretty gentle when flying and landing. I can't afford having a prop strike ruin a day.

 

[Silverburn]

I have APC props on reserve (they are noisy and dependable) and I use Graupner (good luck finding 'em) props on my current craft. I'm pretty gentle when flying and landing. I can't afford having a prop strike ruin a day.

I can find Graupner's here in Switzerland ok (reassuringly expensive too!)...it's the T-motor CF's I can't find in stock *anywhere*..:-(

Re: clones - I did a comparison here on MRF last week. Haven't flown them yet, but when I do, they're going on the training mule until they can earn my respect/confidence! They are at least a replica of the T-motor one piece design.

 

[el gwiz]

This is great to hear about other crashes; my brand new f550 is all glued together and looking a little sad after being hammered into the ground a few times, broken landing gear and it lost an arm. Since I picked it up it's had three sets of new props, eight new motors and a tube of epoxy glue. It still doesn't fly well as I am having trouble re-calibrating everything but I hope , with some advice, I can solve these issues. Looking forward to getting my s800 though.