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NAZE 32 Spinning flip of death

#1
Hi everyone! Rich M here :)
I'm having a problem with my NAZE32 on a 250 sport quad.

It flies great and very stable, easily does all the things you want from an 250 FPV platform, until you cut throttle.

Because it has so much lift, it's hard to get it to lose altitude, while right side up, without almost stopping the props.
But that seems manageable, -just cut throttle, let it drop, engage throttle and catch it at the altitude you want... right?

Well there's the problem...

When I drop throttle to the point the motors stop, re-engaging throttle again causes the quad to spin and flip wildly out of control and come crashing to the ground.

One positive is that the cheap HK frame, hit asphalt and didn't break! Neither did the elite Turnigy HK motors! Go HK! Nice one! :) In fact, after 3 times, doing the same thing, the same day, battery after battery, from 60+ ft up, the whole thing fell apart where it should (foam tape, zip-ties, props) and no components or frame parts got damaged!
Very Lucky!

I thought I saw someone talking about this issue before, but it seems impossible to find anything in these forums.
So after spending 6am-8am today, looking through threads and trying every different search-word I can think of, I figured I'd just ask.

Does anyone know what I'm missing here, or why the Naze 32 does this?
Sorry for the trouble, and thanks everyone, for making a great community!
 

Flat4

Senior Member
#2
Hey Rich, welcome to forums!!!

There are a few things you can do. In cleanflight you can uncheck the motor_stop option on the configuration page. This will cause your motors to spin at their Minimum Throttle set by cleanlfight, when you bottom out your throttle stick. That setting will prevent the motors from coming to a complete stop while in the air, preventing it from just flipping out of the sky when you drop throttle.

However, that will only keep your P's and D's active from your pid loop. Being that your I gain is what holds your craft's attitude, you'll find the copter will still list to a side when the throttle is cut, but it will be much slower and more controllable than what's happening now.

You have two options to have complete control over the craft when your throttle is dumped. If you would like to stick with cleanflight, you can setup and idle up switch. Basically this is a mix done on your transmitter that when activated will always apply a certain level of throttle. You want the throttle to be just high enough to keep your full PID loop active. So even when you cut throttle with the stick, that mix will keep the value high enough that the copter won't stop the motors. Here's a great thread going into more detail on it. http://forum.flitetest.com/showthread.php?8793-Throttle-Cut-Mix-on-a-Multirotor

You're other option would be to use Boris B.'s Betaflight firmware. He has added a flight mode to it called Airmode that has a similar effect to the Idle Up switch. It goes a bout it in a slightly different fashion, but gives a similar effect. Here's a great write-up on it. http://blog.oscarliang.net/betaflight-airmode/
 
#3
Is a quadcopter usually supposed to fall flat if the motors are cut? The only experience ive had with quadcopters right now are the cheap $50 ones from walmart and ive gotten so used to the idea that you dont cut power to free-fall because once you boot back up, the quad copter would tip and basically pull itself into the ground if it flipped over. Do the 250s stay upright for the most part? Also, would you do that in acro mode?
 

Craftydan

Hostage Taker of Quads
Moderator
Mentor
#4
RCN,

It depends -- if the "minThrottle" isn't set right (with or without Motor_stop), one motor will kick out a split-second earlier than the others, sending the frame into a tumble. If minThrottle is set above each motor's minimum "On" signal, then they all kick off at the same time, and it will mostly fall in the attitude it was in -- it might have a slight angular drift but unless the airframe is shaking badly, it should be minimal.

In reality, while I prefer having motor_stop on (others don't, I know why, I disagree on the same grounds, and that's fine), you NEVER want to have the ESCs stop when you don't want the airframe to plummet to the ground (desirable for ~1" AGL, rough at 100', but there's reasons for each). All ESCs have a brief spool-up time to smoothly get the motor to a controllable speed without burning anything out with excessive start-up current. Add on active braking/damping and the ESCs actively halt the props below min throttle. Then, not only does it have to electrically spin-up, it has to do it with out any remaining momentum in the motor. Some ESCs are worse than others, but all are bad enough that it doesn't end well when done in flight.
 
#5
Could you be talking about "Vortex Ring State"? Check this video out; 'splained a bunch to me...:applause:


I did a bunch of practice flights after watching it; it really takes discipline to NOT hit the throttle full-blast!!
Gman
 
#6
Thanks for the help!

Thanks for the comments folks!... been way too busy lately. I caught something awful on a business trip, took a while to get over it, and it's been catch-up catch-up catch-up, for weeks!

I think the answer I got from Flat4 will sort things out. Thank you very much for the info Flat4.
I think it's a break in the feedback loop thingy :)

It's definitely not VRS, or anything that subtle. It's a violent and rapid spinning and flipping, uncontrollable plummet straight down to the ground. The motors sound like they are all at max throttle, there's zero control.

It happens when I restart the motors, from dumping throttle during a rapid descent maneuver. I think it's because I'm using the switch activate function for the motor start up.
The motors stop dead when I dump throttle, the feedback loop is cut, and the whole thing flips and spins wildly, and comes down really fast, when I try to throttle up again.

Some quads I have flown, allow you to completely cut throttle if you want to rapidly drop altitude, then kick in the throttle and catch yourself again. Trying that with the naze32 set up the way I have it was disastrous. LOL

Thanks for the help!
 
#7
some news?

Thanks for the comments folks!... been way too busy lately. I caught something awful on a business trip, took a while to get over it, and it's been catch-up catch-up catch-up, for weeks!

I think the answer I got from Flat4 will sort things out. Thank you very much for the info Flat4.
I think it's a break in the feedback loop thingy :)

It's definitely not VRS, or anything that subtle. It's a violent and rapid spinning and flipping, uncontrollable plummet straight down to the ground. The motors sound like they are all at max throttle, there's zero control.

It happens when I restart the motors, from dumping throttle during a rapid descent maneuver. I think it's because I'm using the switch activate function for the motor start up.
The motors stop dead when I dump throttle, the feedback loop is cut, and the whole thing flips and spins wildly, and comes down really fast, when I try to throttle up again.

Some quads I have flown, allow you to completely cut throttle if you want to rapidly drop altitude, then kick in the throttle and catch yourself again. Trying that with the naze32 set up the way I have it was disastrous. LOL

Thanks for the help!
I have the same behavior when i use my 4s lipo (not with 3s)
have you some solution since or you are living with the problem ?

thx !