Left Stick Lock down and CSC two stick down and together !

[jwmcgrath]

CSC is a terrible way to stop the motors when landing or on the ground!! The very act of pulling both sticks down and inward (CSC) will make the phantom respond to those movements and flip the thing over. DJI is very wrong to say in the manual that CSC is an option for shutting down the motors on the ground.

Couldn't agree more. There had to be a logical reason for it at some point... someone made the conscious decision to have it written in to the code. But I can't for the life of me understand WHY it would be suggested as one of the two "normal" ways to shut down.

Somebody give me an "ah-HA!" explanation please.

 

[120CCPM]

Same here, tried the CSC on my second landing, the AC almost flipped. No damage, just some minor marks on two props, but I agree it's just plain stupid for DJI to list it as an option to turn off the motors on a normal landing, with the throttle-down method being so intuitive and safe. In my mind, CSC should be presented and used truly as a last-resort emergency procedure... pretty much like a "self-destruct" button:

​

As for testing the CSC in-flight, I have to admit that my desire to learn doesn't push me this far. Having said that, probably the only way to do it - short of sending the AC up 10 meters and hope to catch it when it falls like a brick - is to take off, bring it up a couple meters, have someone FIRMLY holding it by the landing gear, and have the pilot issue the command. Could be quite dangerous, though, as I assume (especially if DJI really introduced this 3s delay) that the AC will vigorously try to respond to the stick positions before killing power to the motors. Nigel, I think this has the potential of becoming great material for a FailArmy video...

 

[Paul60]

Ok, so why does the aircraft not flip when you give the CSC command to START the motors ?

 

[jwmcgrath]

Ok, so why does the aircraft not flip when you give the CSC command to START the motors ?

My guess on that one is because the AC knows that it's not moving... it's just starting up. Therefore it's not trying to respond to stick commands, it knows the command at that time is meant to "start" only.

 

[120CCPM]

Ok, so why does the aircraft not flip when you give the CSC command to START the motors ?

It's very simple: when you start the motors, the AC is on the ground with the motors off, so you can move the sticks as slow as you want to go to CSC. The moment CSC is detected, the AC will start spinning the motors, but you have time to let the sticks go and return to center. Actually, I would not be surprised if the firmware gives you some "grace time" after a CSC-START, before actively reading and responding to the stick position. It could even be that it waits for the sticks to go back to center, before entering "flight mode". It would be quite easy to test, actually (with the props off).

When you use CSC to turn the motors off, the AC is actively responding to stick positions. This means that your inputs are interpreted as flight commands (yaw/throttle/pitch/roll) until the AC detects a CSC-STOP. If you're not fast, or if you're slower with one stick compared to the other, the AC has enough time to flip.

 

[jwmcgrath]

It's very simple: when you start the motors, the AC is on the ground with the motors off, so you can move the sticks as slow as you want to go to CSC. The moment CSC is detected, the AC will start spinning the motors, but you have time to let the sticks go and return to center. Actually, I would not be surprised if the firmware gives you some "grace time" after a CSC-START, before actively reading and responding to the stick position. It could even be that it waits for the sticks to go back to center, before entering "flight mode". It would be quite easy to test, actually (with the props off).

When you use CSC to turn the motors off, the AC is actively responding to stick positions. This means that your inputs are interpreted as flight commands (yaw/throttle/pitch/roll) until the AC detects a CSC-STOP. If you're not fast, or if you're slower with one stick compared to the other, the AC has enough time to flip.

Ya. That's what I meant. [emoji6]

 

[N017RW]

If you use CSC as a shut-down after landing, you're supposed to do full throttle down, then move the other three channels to the CSC position.

Positioning all 4 channels simultaneously does run the risk of ground looping which is not a concern with a mid or in-flight emergency.

 

[Paul60]

When starting, it seems to me there is enough time for the stick positions to be interpreted by the aircraft as 'stick movements' as they travel back to their neutral (mid) positions. But anyway.

I've never had a tip over and I always use full throttle down to stop the motors

 

[120CCPM]

If you use CSC as a shut-down after landing, you're supposed to do full throttle down, then move the other three channels to the CSC position.

Throttle-down is enough to turn off the motors. If you use this method, the position of the other 3 channels is irrelevant.

Positioning all 4 channels simultaneously does run the risk of ground looping which is not a concern with a mid or in-flight emergency

That's exactly what many of us are saying...

 

[jwmcgrath]

When starting, it seems to me there is enough time for the stick positions to be interpreted by the aircraft as 'stick movements' as they travel back to their neutral (mid) positions. But anyway.

I've never had a tip over and I always use full throttle down to stop the motors

I'm pretty sure they have to be allowed to return all the way to neutral position after starting before they start sending commands to the craft. ALMOST positive.

 

[120CCPM]

When starting, it seems to me there is enough time for the stick positions to be interpreted by the aircraft as 'stick movements' as they travel back to their neutral (mid) positions

I just did a quick test with AC on the ground, no props. After you issue a CSC-START, the motors do their "zoom zoom" (for lack of better term...) and that gives you time to bring the sticks to center position. After the "zoom zoom", the AC starts reading the positions of the sticks as flight commands and does NOT wait/need for them to go back to center: if you keep the sticks at CSC position, you will hear the motors go through their "zoom zoom", then - with minimal delay - they will start spinning faster as the AC is trying to respond to the sticks.

I'm pretty sure they have to be allowed to return all the way to neutral position after starting before they start sending commands to the craft. ALMOST positive.

From the test I did, it seems it's not the case.

This test is non-conclusive as the AC knows it's not in flight, so take it for what it is.

 

[Paul60]

I've got a Blade 350QX and a CX-20 that both use similar startup-stop stick movements. Never had a tip over or issues. Never gave it much thought. I haven't flown either for a while. I might blow off the cobwebs and refresh my memory with a couple of flights.

The 350QX with a Spektrum DX6 Tx has a red kill button. Accidently hit that in flight and it's all over !

 

[jwmcgrath]

I just did a quick test with AC on the ground, no props. After you issue a CSC-START, the motors do their "zoom zoom" (for lack of better term...) and that gives you time to bring the sticks to center position. After the "zoom zoom", the AC starts reading the positions of the sticks as flight commands and does NOT wait/need for them to go back to center: if you keep the sticks at CSC position, you will hear the motors go through their "zoom zoom", then - with minimal delay - they will start spinning faster as the AC is trying to respond to the sticks.


From the test I did, it seems it's not the case.

This test is non-conclusive as the AC knows it's not in flight, so take it for what it is.

Thanks for the clarification and test... since I was WAY too lazy to open the box... seemed like a lot of work. Good to know because I don't think I ever really paid that close attention...

Instinct I think to release instantly after starting... kinda like letting go of the key after the engine starts.

 

[Monte55]

If you use CSC as a shut-down after landing, you're supposed to do full throttle down, then move the other three channels to the CSC position.

Positioning all 4 channels simultaneously does run the risk of ground looping which is not a concern with a mid or in-flight emergency.

This is absolutely correct. After landing, I can use either method and have no problems. The key to CSC is to lower throttle first followed by right stick as in this video I made. Don't think it would be different on later Phantoms.I normally use throttle down because I usually hand catch.
.

 

[120CCPM]

This is absolutely correct. After landing, I can use either method and have no problems. The key to CSC is to lower throttle first followed by right stick as in this video I made. Don't think it would be different on later Phantoms.I normally use throttle down because I usually hand catch.

Oh, I understand now what N017RW was saying... the point is to throttle-down then immediately move to CSC, vs. going to CSC with both sticks simultaneously from center. Sorry for the misunderstanding, my response was a bit off-target, then.
But even now, I still don't quite understand why someone would want to do something like that, since throttle-down by itself will turn off the motors. Am I missing something?

 

[Monte55]

Oh, I understand now what N017RW was saying... the point is to throttle-down then immediately move to CSC, vs. going to CSC with both sticks simultaneously from center. Sorry for the misunderstanding, my response was a bit off-target, then.
But even now, I still don't quite understand why someone would want to do something like that, since throttle-down by itself will turn off the motors. Am I missing something?

CSC is a faster shutdown....at least it is on my birds. It's almost instant compared to the throttle down only method which can take a few seconds. If I'm landing on the lawn I will usually use CSC so if the bird tips over it won't grind the prop into the ground . If you watched the video, you will notice that the first landing as smooth as it was still tipped over once the props were slow enough they couldn't keep the Phantom level. Doesn't take much for a Phantom to tip over on uneven ground.

 

[120CCPM]

CSC is a faster shutdown....at least it is on my birds. It's almost instant compared to the throttle down only method which can take a few seconds. If I'm landing on the lawn I will usually use CSC so if the bird tips over it won't grind the prop into the ground . If you watched the video, you will notice that the first landing as smooth as it was still tipped over once the props were slow enough they couldn't keep the Phantom level. Doesn't take much for a Phantom to tip over on uneven ground.

Ok, got the P3S out again and did one more (and last, for the night) test, on the ground and without props, so take it for what it is: throttle-down immediately followed by CSC does not stop the motors right away. There is as much of a delay - if not more, actually - than throttle-down by itself.
The latest 1.8.10 firmware for the P3S (quote) "slowed motor stopping time to three seconds during flight". Maybe its not just "during flight", so the CSC is now delayed 3 seconds, exactly like throttle-down...
Anyways, I'm not trying to convince anyone of anything, I think throttle-down is so simple and intuitive that I'm actually surprised to see DJI listing CSC as the first method to stop the motors (Page 43 of the Manual).

 

[solentlife]

Now that lively debate has commenced - that's better. There's a lot of sense and info coming in now generated by what a few looked upon as 'stupid'.

OK - let's move on a touch ...

The Left Stick Lock Down function - I do not suggest to use all the way to actual touchdown. My reason for that is the likely speed of touchdown. I have always 'unlocked' the stick just above ground to then slow the descent to a nice gradual rate.

Just a short comment to those who quote out of other models manuals - many of us here only own P3S and do not read or have reason to read an Inspire or other manual. We have the P3S manual which generally is sufficient.

Thanks guys for bearing with me and providing good discussion.

Nigel

 

[Paul60]

The Auto Takeoff/Land works great for me too I should add.

 

[solentlife]

The Auto Takeoff/Land works great for me too I should add.

As it does for me as well ... I just prefer to manually land that last bit ...

Auto-land and Left Stick Down appear to have different descent rates as I observed. The Left Stick Down at the max rate AC is set by FW. Auto seems to be less.

(There's all sorts of 'fluff' about ground-effect taking over last few feet ... well given the type of airframe and its lack of surface area - that can only really be in last few inches ! Certainly not feet. Even a Helicopter with its massively larger rotors only has any ground effect coming in when its LESS than one rotors height from ground. Its why a Heli can dance about when close to ground and needs to be lifted a touch more).

Nigel