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Full throttle descent question
2171 25 2015-4-2
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drklion
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For those that may have done a full throttle descent (just using left stick fully pressed down) without knowing that it would put the bird into a VRS did you notice the bird stable or did it rock back and forth?


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2015-4-2
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DJeff1
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I would not attempt a full throttle descent because of the possibility of the introduction of a vortex ring state.
2015-4-2
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Ph02on
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This is known as Vortex Ring State.  Full throttle decents should be avoided at all cost. This video will explain better than I can.



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Jason
2015-4-2
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drklion
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I understand the vortex ring state.  I am concerned on the stability.  On the Inspire 1 it seems to stabilize this descent to avoid the VRS if in full throttle descent.  I AM NOT ASKING ANYONE TO TRY IT.  Please let me know if you can recall stability or the rock and roll motion from experience.

Thank you.
2015-4-2
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DJeff1
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I have not experienced because I do not do full throttle descents.
2015-4-2
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w1der
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If you push the right stick slightly "forward" (or any direction) at the same time as you push the left stick down to the maximum, you will get a stable flight downwards ...
If you don't do this it starts "rocking" ... YES!
2015-4-2
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kgarrison
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Yes, it will wobble while it tries to maintain stability. This is why it is a very very bad idea to do a full throttle descent.
2015-4-2
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Dangair
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If you pull the left stick all the way down and hold it there for a few seconds you may land a tad faster than expected!
2015-4-2
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markjacobs.talk
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Dangair Posted at 2015-4-3 01:46
If you pull the left stick all the way down and hold it there for a few seconds you may land a tad f ...

If you push the right stick into the bottom right and push the left stick to the bottom left at the same time you land even quicker!  
2015-4-2
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wolftj
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drklion - Read up on VRS and you will be able to answer your own question, I believe.
2015-4-2
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drklion
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wolftj@mindspri Posted at 2015-4-3 03:37
drklion - Read up on VRS and you will be able to answer your own question, I believe.

Yes, I understand VRS as mentioned above.  I am looking for some who may have done the full throttle descent without realizing it is a bad idea and may have noticed that it was stable or wobbled because of the VRS.

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2015-4-2
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jhogge
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"If you push the right stick slightly "forward" (or any direction) at the same time as you push the left stick down to the maximum, you will get a stable flight downwards ...
If you don't do this it starts "rocking" ... YES! "

Exactly as this poster stated. When I need to descend quickly I fly in wide circles to maintain forward movement and it is perfectly stable.

If no forward movement it will start rocking enough to scare the crap out of me.
2015-4-2
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drklion
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jhogge Posted at 2015-4-3 06:29
"If you push the right stick slightly "forward" (or any direction) at the same time as you push the  ...

Thank you for the reply.
2015-4-2
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doctrrf
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I've used full left stick down with my Inspire 1 many times with no problems.
Most of the death wobbles are caused in part by low batteries: typically VRS occurs late in the flight, the battery is low, and the motors simply don't have enough punch to correct the wobble unless you correct and get some lateral movement going to bring in clean air.

Here's my Phantom 2 playing around with VRS:  


2015-4-2
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dlew21
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drklion Posted at 2015-4-3 00:26
I understand the vortex ring state.  I am concerned on the stability.  On the Inspire 1 it seems to  ...

Should be normal
2015-4-2
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dlew21
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doctrrf Posted at 2015-4-3 09:05
I've used full left stick down with my Inspire 1 many times with no problems.
Most of the death wobb ...

I've never had a wobble on full throttle descent..  I think it is a battery issue
2015-4-2
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rickc309
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I do full throttle decents now and then. The I1 handles it perfectly. My P2 also has no issue at all with it.
2015-4-2
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drklion
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Thank you all for the reply.  Now it is starting to be clear.  The battery may be at fault if not fully charged or at least have enough juice to counter act the VRS.  Again thank you all for your input.

If I get some info from DJI I will post.
2015-4-2
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Dangair
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markjacobs.talk Posted at 2015-4-3 01:53
If you push the right stick into the bottom right and push the left stick to the bottom left at the ...

No it will take same amount of time as pulling the left stick to the bottom and holding it there will kill all motors too.
2015-4-2
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doctrrf
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Dangair Posted at 2015-4-3 12:35
No it will take same amount of time as pulling the left stick to the bottom and holding it there w ...


The left stick, by itself, held down will kill the motors only after landing, same as the Phantom 2. In fact, the latest Phantom controller comes with a clamp on the left stick to hold it down during descent.
2015-4-2
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Dangair
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Have you tested this? Because I pulled the left stick down on the sim and she landed rather quickly!  The fear I have is that it will behave oddly like so many other glitches that have surfaced and I will have a lawn dart!
2015-4-3
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ssteenberg
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I use full throttle all the time to bring it down.
2015-4-3
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markjacobs.talk
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Dangair Posted at 2015-4-3 12:35
No it will take same amount of time as pulling the left stick to the bottom and holding it there w ...

No it wont.

Left stick to the bottom will be minimum throttle but will not cut off the motors as long as the internal barometer is receiving changing barometric pressure data.
CSC command will kill the motors IMMEDIATELY irrespective of any other sensor or flight controller condition.
So you are incorrect since minimum throttle will maintain flight, but CSC will initiate free fall and the Inspire will achieve terminal velocity.
2015-4-3
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drklion
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doctrrf Posted at 2015-4-3 09:05
I've used full left stick down with my Inspire 1 many times with no problems.
Most of the death wobb ...

So far you have been correct.  All indications fall on the battery power.  No problem today with full throttle descent and battery fully charged (90%).  

It does not mean it is safe to do.   I am not condoning this maneuver.
2015-4-3
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Dangair
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Good! I'm glad I'm incorrect. I was seriously concerned about that and was thinking of hang testing it. But if you guys are saying that you have confirmed that the throttle alone won't kill it in flight, that answers my question. I find sometimes that the best way to get a response on threads is to raise a hackle. You are sure to get one then! Nice job and thanks.
2015-4-4
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drklion
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Dangair Posted at 2015-4-5 01:38
Good! I'm glad I'm incorrect. I was seriously concerned about that and was thinking of hang testing  ...

Just to be clear: I have done a full throttle descent with a low battery charge and I had an issue with wobble, possibly a VRS and have done a full throttle descent with a charged battery at 90% and did not have any wobble, very stable.  It does not mean I feel the motors are ok in this maneuver.  I would have to do some more testing.  My concern was if the Inspire 1 was stable on the full throttle descent and it looks like the battery charge plays a big part on its stability.  So with that information I would venture to say that with a strong battery the Inspire 1 is making all the diagnostics and calculations for a safe descent and possibly refraining on stressing the motors as apposed to a weak battery.
2015-4-4
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