I just got the new transmitter for my Vision 2 Plus.  upgraded all the software and calibrated it.  I have not flown it yet but I am concerned that if I am at altitude and I put the throttle in the lock position it will kill the motors after a few seconds.  I tested my theory by turning on the motors without the propellors.  I then held the quad in the air and while moving it around put the throttle in the lock position.  After a few seconds the motors did indeed stop.

Can anyone tell me the logic of the throttle lock and in real world flying, will it drop from the sky if I inadvertantly lock it at altitude?  I can't imagine it would be different from the old transmitter in that the normal operations to shut off the props (ie holding down after landing and moving both sticks to center and down).

If this is NOT a concern please explain how the quad knows the difference between a landing situation and in flight situations?

Thanks!

When you are descending, the Phantom will know by the downward movement and not shut down.  When it lands, no movement for 3 seconds, then it will shut down.

Gerry1124 Posted at 2014-12-4 11:24
When you are descending, the Phantom will know by the downward movement and not shut down.  When it  ...

I figured the logic must be the same as the old transmitter BUT, like I said I started the motors, and while I was walking around and gyrating the quad I put the throttle lock on and the motors stopped in the normal time it takes to stop upon landing.  Am I imagining a problem?

atoddmiller Posted at 2014-12-4 11:31
I figured the logic must be the same as the old transmitter BUT, like I said I started the motors,  ...

It's not the kind of thing one wants to test....  ;)  Thanks for helping me with my confidence.  I have to ask myself why in the heck would they put a throttle lock on the transmitter for any other reason than to assist decent.  I am sure you're right.

The barometric pressure change will be nil with you just waving it around in the air.  It will take 3 seconds to stop, and since you're moving at about 2 meters per second descending, that would be about 19 to 20 foot drop.

Thanks Gerry1124.  

atoddmiller Posted at 2014-12-4 11:44
Thanks Gerry1124.

My rule of "thumb" literally, I wedge my thumb between the bottom of the frame where the throttle stick is and just pull back on descent until I hit my thumb.  It's about 3/4 down.

Gerry1124 Posted at 2014-12-4 11:46
My rule of "thumb" literally, I wedge my thumb between the bottom of the frame where the throttle  ...

So are you saying you don't push your luck and hold the stick all the way down for decent?

atoddmiller Posted at 2014-12-4 11:56
So are you saying you don't push your luck and hold the stick all the way down for decent?

To much money tied up in my machines to experiment.

I completely agree with you why risk it?  Thanks for the help.  The throttle lock can, in a way, act like your thumb in that it is an indicator point before minimum throttle position.

I have a new Inspire 1 coming and I like that it has Ultrasonic sensors.  This would, or should, again I'm not sure what the programming logic will be, alleviate the potential failure mode we're talking about.  Wonder why the Phantom doesn't have them?  They are cheap.  My Parrot which I have had for 3 years has them.

Thanks again Gerry1124.

The ultrasonic sensors will allow you to fly inside a building with no gps lock.  It will only work to around 8 to 10 feet from what I understand about it.  Once outside, gps lock will be the primary stability controller.

There is a YouTube video of someone who tested this; they locked the throttle down and the Phantom did in fact shut down.  In fast descent just pull down until you feel the bottom (before the lock); don't go lower.

kenargo Posted at 2014-12-4 12:38
There is a YouTube video of someone who tested this; they locked the throttle down and the Phantom d ...

I saw the video, when he moved both sticks down and to the center it did in fact shut down.  Then he repeated the test and moved the throttle stick down and it in fact did not shut off.

kenargo Posted at 2014-12-4 12:38
There is a YouTube video of someone who tested this; they locked the throttle down and the Phantom d ...

Then what do you suppose the throttle lock is for or is this simply a. Design weakness?  

kenargo Posted at 2014-12-4 12:38
There is a YouTube video of someone who tested this; they locked the throttle down and the Phantom d ...

Can you post the link?

Gerry1124 Posted at 2014-12-4 12:42
I saw the video, when he moved both sticks down and to the center it did in fact shut down.  Then  ...

Maybe it is a different video. Can you post a link to the one you saw?

I wish I could find it again; I remember it well because the comments where around how crazy this person was to even test such a thing.  If I find it I'll post it.

kenargo Posted at 2014-12-4 12:50
I wish I could find it again; I remember it well because the comments where around how crazy this pe ...

I can't remember where it is either, I thought I saved it.

kenargo Posted at 2014-12-4 12:50
I wish I could find it again; I remember it well because the comments where around how crazy this pe ...

Got it,



Moving both sticks down and to the center did shut off the motors, but, moving the throttle stick all the way down to descend, did not shut off the motors.

Found it; not the V3 controller but I don't think the operation is controller specific.



There was also a thread about this a while back:

http://forum.dji.com/forum.php?mod=viewthread&tid=760
and
http://forum.dji.com/forum.php?m ... age%3D2&lang=en

So possible, I would say yes.

kenargo Posted at 2014-12-4 13:06
Found it; not the V3 controller but I don't think the operation is controller specific.

https://www ...

Did you see HOW he shut them off in mid flight?  He moved BOTH sticks in the down center position. so the phantom would be coming down spinning and full reverse and sliding sideways.  Now, on a descent, only the throttle would be pulled to the extreme down position and it did not shut off.

If you look at the 1st thread the person pulled the stick all the way down for a fast descent and reported that his motors shut off.

I was flying my Phantom II Vision+ at about 300ft height and I wanted to come down fast so I pushed the trottle down all the way (Left Stick) and after 3 sec it completely shut down.

I have a vision, it has a controller that looks like the old one, but has the left stick lock.  For me at least on decent I can lock the left stick all the way and leave it there for the full decent.  I can rotate the craft with the right stick to have a look around while it's descending. .  I'm talking quite a time here not just a few seconds.

Now as a test I hovered 3 feet and put the controller in to CSC and the bird dropped like a stone, just like the online instructions said it would do. Putting  one stick alone did not have any change in behaviour.  I don't have enough flying experience to know it it's truly possible, just that it's never happened to me yet.

kenargo Posted at 2014-12-4 13:33
If you look at the 1st thread the person pulled the stick all the way down for a fast descent and re ...

People in a panic do things that they do not realize, or even remember.  According to that statement, the phantom in the video should have crashed when he just pulled the throttle back, but it didn't.  Statement was myth busted.

Hi Guys,  Thank you very much for all the POV's.  I think understanding the logic of how the Phantom differentiates between landing and decent - how do the accelerometers, gyros, GPS, barometric pressure sensors, etc make sure it doesn't shut down when the operator holds the throttle in the down position.

The programming MUST be solid or, as I said before, why would DJI put the throttle lock on the new controller?  I will still avoid descending with the throttle lock.

I'm hoping DJI can enlighten/boost my confidence as using the throttle lock would be a convenient way to lower altitude and give me more capacity to video.

You should have no concerns what-so-ever over using the throttle lock.
The Phantom will not shut down in flight using it.
The only way you can shut the Phantom down in flight is if you use the Cross Sticks Command in an emergency.

johnwarr@live.c Posted at 2014-12-4 20:36
You should have no concerns what-so-ever over using the throttle lock.
The Phantom will not shut dow ...

Thanks for offering that.  however, I can see how, without proper sensors (ultra sonic) confirming terra firma, how the "perfect storm" (i.e. updraft same velocity as decent) could cause a concern but on a nice day I may still use the throttle lock to descend.  I bet the next generation Phamtoms have ultra sonic sensing like the Inspire one.

I really appreciate everyone's input here.  I think I have gained more understanding of the logic used in the Phantom 2 V+.

Another question on this subject..... if the throttle is locked down.... will the descent rate be slow enough to avoid he vortex issues?   AND  I know the programming slows the descent at about 20 feet, but will this feature cause a hard landing once it slows down or it is feasible to use this as an "auto land" - not that I plan on this ...just wondering!  
thanks

The intent of the throttle lock design was probably to facilitate performing certain diagnostic and special bootup procedures that require holding the throttle stick in the full down position against the spring tension, along with some other control inputs that requires 3 hands.         
Back in the 72 MHz R/C days radio manufacturers came out with a multi frequency transmitter knob adjustment as a marketing gimmick that soon earned the name 'Dial-a-Crash'.  There is a distinct possibility that the DJI throttle lock may come to be known as 'Crash Lock' as it could be catastrophic if used in the wrong autopilot mode (for example IMMEDIATE MODE when you must maintain greater than 10% throttle or the motors suddenly stop, even when not performing the two stick CSC procedure).  Can't happen to you?  Asiana Airlines crashed a full scale 777 at San Francisco International because the pilots lost track of what autopilot mode was active.

question, my left stick is the one that locks (which in my layout is the forward/back axis NOT the throttle axis).  it seems odd to have it lock and me not be able to disable that feature of the RC.  it has locked inadvertently on my twice during flight (of course i sense that quickly and react but still not a good design).  i get how in a 'three handed test situation' you'd want a lock, but come on, a clinical scenario like that doesnt justify a feature that can cause such headache for your end user.  am i missing what other inherent value something like that has?  or is there some way to disable it that I am unaware of?

gnixon@comporiu Posted at 2014-12-26 23:45
question, my left stick is the one that locks (which in my layout is the forward/back axis NOT the t ...

So you're flying in mode 1 and prefer the throttle stick on the right?

yes, i prefer right throttle stick.  however, even if i wanted throttle on left, why would i want it to lock, it isnt that hard to hold a stick down, the thing is like a feather.  ??

gnixon@comporiu Posted at 2014-12-26 23:56
yes, i prefer right throttle stick.  however, even if i wanted throttle on left, why would i want it ...

Inside the tx is a small piece of metal screwed to the left hand stick, about 1/8 of an inch wide.  In the left hand stick is a little plastic piece attached to the stick.   To disable the lock, just take the 4 screws out of the back of the tx, be careful as there is a wiring harness attaching both halves together and unscrew the small metal strip on the left hand stick.  That gets rid of the throttle lock.  Problem solved.

thanks a bunch gerry!

gnixon@comporiu Posted at 2014-12-27 00:41
thanks a bunch gerry!

Just be careful when you take the front and back apart, the antenna has a collar on it to connect the halves together and has to be reinserted at an angle.
This video is for adding better antenna to the TX, but it will explain how to take the TX apart and get the antenna out.

It looks like all you would have to do is remove the little metal strip with the screws and bag it up and save.