From what I know, my MA2 flies the way it is supposed to. It is very smooth except when doing a vertical descent (holding left stick only straight down or at the end of RTH), when both the sound and the drone seem to oscillate during descent. All other flight modes are smooth. If the descent is angled forward or backward it is smooth. But straight down does not seem smooth. This is my first drone and I was wondering if this is normal.
Vertical descent not smooth
- Thread starter Ben Anderson
- Start date
itsneedtokno
I'm chillin, appreciate it though.
It's got to do with physics.
Straight down descent is tricky for a quad because each motor has to constantly adjust for the balance of the AC.
Flying forward while flying down will not only cause faster decent (on the MA2 anyway), but sound cleaner... If that's an issue for you.
There is absolutely nothing wrong with your drone though. ?
Straight down descent is tricky for a quad because each motor has to constantly adjust for the balance of the AC.
Flying forward while flying down will not only cause faster decent (on the MA2 anyway), but sound cleaner... If that's an issue for you.
There is absolutely nothing wrong with your drone though. ?
itsneedtokno
I'm chillin, appreciate it though.
I mean, that's also unnecessary.
It's your personal preference though.
On descent it may sound like it's going to flip over or do some crazy thing, but I can assure you, it's not.
(I'm going to try to describe it in 100 words or less) Think about a boat or car... When going forward they have a steady tone to the exhaust note, but if they get airborne the RPMs max out for that moment, then when they hit friction again the note comes back to normal.
That's what you are hearing, but x4 (for each motor). During forward flight or ascent, the friction is a constant force, but on descent the friction is variable based on wind etc.
Friction might be the wrong word, but the physics behind the reasoning are there lol.
EDIT: NOT A PHYSICIST (there are some around here). Just a critical thinker with an IQ over 140. This is my understanding of what's happening.
I completely understand what's going on, but the sound often frightens people or pets that may be around.
What's happening is the same reason why helicopters aren't always perfectly flat. Unlike helis, quads can only direct air in one direction. The easiest explanation is "dirty air". The expelled air is interfering with clean air. That's what causes the "crazy" buffeting.
What's happening is the same reason why helicopters aren't always perfectly flat. Unlike helis, quads can only direct air in one direction. The easiest explanation is "dirty air". The expelled air is interfering with clean air. That's what causes the "crazy" buffeting.
It is not smooth because it is descending into its own prop wash, which is turbulent air.
This is also why DJI limit the descent speeds, if it comes down too fast it can enter what is called "vortex ring state" ( google it) which can lead to a crash. The danger of entering vortex ring state can be avoided by moving away from the prop wash i.e forward, backwards or sideways but DJI play safe and limit the descent speed. Moving away, if feasible, is still good but in some instances pure vertical is the only option.
This is also why DJI limit the descent speeds, if it comes down too fast it can enter what is called "vortex ring state" ( google it) which can lead to a crash. The danger of entering vortex ring state can be avoided by moving away from the prop wash i.e forward, backwards or sideways but DJI play safe and limit the descent speed. Moving away, if feasible, is still good but in some instances pure vertical is the only option.
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itsneedtokno
I'm chillin, appreciate it though.
I was just getting ready to drop the "vortex ring state" info on em.
itsneedtokno
I'm chillin, appreciate it though.
"Dirty Air"
"Prop Wash"
"Vortex Ring State"
Those were the terms I was missing.
Good job guys.
And yeah, the sound of descent is the only off-putting sound the MA2 makes. I can't even hear the bird on the beach. It's great.
itsneedtokno
I'm chillin, appreciate it though.
bmwbob
Well-Known Member
Mine was bouncing around on decent yesterday due to wind and landed exactly where it left from.
Descending fast vertically in sport mode is the worst, for the MM anyway. Full disclosure, I don't have an MA2. 'Dirty air' is indeed a good description.
Someone with a better handle on the physics and flight logs will probably correct me but I think of it as falling into a series of self-created 'holes in the air'. As a result of the reduced lift created by the downforce from the vortex ring, the a/c momentarily picks up downward speed and RPMs rise, until it has descended far enough to find cleaner air. Then it may re-occur unless you break the cycle by, for example, letting go of the sticks.
I need to practise a different style of fast, almost vertical, descent myself. I'm thinking I'll probably try full down left stick with slight forward pitch on the right stick. I might over- or under-shoot the landing point sometimes but that would be easier on the a/c and my nerves. Descending slower is the other option but that makes it a sitting duck for a hawk attack. We coexist, mostly happily, with a lot of raptors up here.
https://upload.wikimedia.org/wikipedia/commons/c/cb/Vortex_ring_helicopter.jpg
en.wikipedia.org
Someone with a better handle on the physics and flight logs will probably correct me but I think of it as falling into a series of self-created 'holes in the air'. As a result of the reduced lift created by the downforce from the vortex ring, the a/c momentarily picks up downward speed and RPMs rise, until it has descended far enough to find cleaner air. Then it may re-occur unless you break the cycle by, for example, letting go of the sticks.
I need to practise a different style of fast, almost vertical, descent myself. I'm thinking I'll probably try full down left stick with slight forward pitch on the right stick. I might over- or under-shoot the landing point sometimes but that would be easier on the a/c and my nerves. Descending slower is the other option but that makes it a sitting duck for a hawk attack. We coexist, mostly happily, with a lot of raptors up here.
https://upload.wikimedia.org/wikipedia/commons/c/cb/Vortex_ring_helicopter.jpg
Vortex ring state - Wikipedia
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I'd noticed this with mine too- a straight down descent saw it wobbling around like a top (although the footage holds up well with the gimbal I think!) - I figured it was probably normal as it's constantly having to adjust each motor to keep it steady
Vertical down has the quad descending through its own prop wash. The downward air rushes outward and makes a toroidal (visualize a doughnut with hole in middle) flow which returns back to the top of the blades. It becomes a vicious cycle of unstable air.
Slight transitional motion - fwd, back, L/R keeps machine in clean air and fixes this problem...
Slight transitional motion - fwd, back, L/R keeps machine in clean air and fixes this problem...
Thanks, everyone, for your information on this topic. I even read up on vortex ring state 
I see that the MA2 User Manual v1.2 says the following:
Max Flight Time 34 mins (measured while flying at 18kph in windless conditions)
Maybe 18kph is the most efficient forward speed to minimize vortex ring state while maximizing battery life.
I see that the MA2 User Manual v1.2 says the following:
Max Flight Time 34 mins (measured while flying at 18kph in windless conditions)
Maybe 18kph is the most efficient forward speed to minimize vortex ring state while maximizing battery life.
No need to minimize vortex ring state while flying forward. Only applies to vertical descent.Thanks, everyone, for your information on this topic. I even read up on vortex ring state
I see that the MA2 User Manual v1.2 says the following:
Max Flight Time 34 mins (measured while flying at 18kph in windless conditions)
Maybe 18kph is the most efficient forward speed to minimize vortex ring state while maximizing battery life.
Actually the forward speed is most efficient - it uses transitional lift. A lot more power is required for stationary hover. A full scale helicopter will takeoff and immediately start forward motion for transitional lift, which requires less power, and to remain in "clean" air.
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