Hi , thursday and friday i will go with me school classmates to a small place in the south of belgium to make some photography ,we are student in infographics / photography arts and me teachers want that i take me PH3 to take pictures with it , we gonna make something like 4 to 5 hours of photography and i have only 2 batteries... i know the ATTI mode use less battery but how much ? beaucause the wind is very strong in our region and they gonna be much of threes in this place and im not a very experimented pilot ( i have only 9H38 in flight ).
So me questions is how long can me aircraft stay in ATTI mode in flight with wind and in a cool place ( something like 12 celsius degrees )
and what esle can i do to flight the long time as possible ?

I would advise you to stay out of atti mode to keep the class safe.

This sounds like a very tricky and uncomfortable situation for you.  You should proceed very cautiously.

I've never heard that ATTI mode uses less battery, but I have heard and know that aggressive flying in ATTI mode can contribute to sharp dips in individual cell voltage which can cause a flight to be shorter.  Sounds like you will have trees?  You will be flying above them or within them?  If you are above them, I would use GPS mode.  If you are flying within them, you could use ATTI mode because you may not have GPS or GPS will be intermittent,, but you need to practice first in a field with no trees at very close range and very slowly.  Do it tomorrow.  I would not fly within the woods without practice first in an open field.  

If you cannot practice, I would tell your teachers you cannot fly in the woods on a very strong windy day.  

If you can practice, you may decide it's too risky to fly in the woods on a very strong windy day.  

If you do decide to fly in the woods, you might consider prop guards.

Remember to keep your batteries warm before flight.

Remember you must have batteries fully charged before flight!  With two batteries, that means two flights maximum.  So two flights - maybe 20 minutes each.  Know you cannot fly four flights for 10 mins each.  It must be two flights.  

Good luck.  

Edit:  Here's a very boring unedited video of a flight in the woods this past Sunday.  I flew in GPS mode, but it was constantly going in and out, and if I did it again, I'd just leave it in ATTI.  Note that the air in this video is CALM.  But the AC still does not hover in one place.  

ATTI mode will use less battery only if you let the aircraft drift away in the wind.  (In GPS mode is has to counteract gravity and add a horizontal component to counter the wind.)  But if you let it drift in the wind, then the aircraft isn't where you want it to be, so what good is that?

Strong winds in ATTI mode in an unfamiliar location isn't a good place for a low-hours pilot to be.  I wouldn't want to be dealing with a bunch of people while I had my hands full with the aircraft and the wind/terrain.  If you crash, show the class how to crash like a man!

Mark The Droner Posted at 2017-10-24 10:53
This sounds like a very tricky and uncomfortable situation for you.  You should proceed very cautiously.

I've never heard that ATTI mode uses less battery, but I have heard and know that aggressive flying in ATTI mode can contribute to sharp dips in individual cell voltage which can cause a flight to be shorter.  Sounds like you will have trees?  You will be flying above them or within them?  If you are above them, I would use GPS mode.  If you are flying within them, you could use ATTI mode because you may not have GPS or GPS will be intermittent,, but you need to practice first in a field with no trees at very close range and very slowly.  Do it tomorrow.  I would not fly within the woods without practice first in an open field.  

DJI's standard qualifier for flight time determination is "At sea level in calm environments when flying in ATTI mode, the flight time will vary due to different flight patterns, weather conditions, and altitudes."

This would clearly indicate that the most likely mode to achieve the maximum stated flight time out of a battery would be ATTI.  Of course along with a few other qualifiers as well, in other words you'll likely never achieve full stated time of a battery's ability unless in a laboratory or in perfect conditions as stated or dumb luck.  Either way you cannot even begin to get there unless you are in ATTI mode.

So my question is how long can me aircraft stay in ATTI mode in flight

Flight time will be the same whether you fly in Atti or P-GPS mode.
There are many reasongs you should be in P-GPS mode but I can't think of any reason for you to use Atti mode for what you want.
It won't give you any advantage.

Under laboratory conditions you might get a few seconds more but in normal use you wouldn't be able to measure any difference.

ALABAMA Posted at 2017-10-24 10:49
I would advise you to stay out of atti mode to keep the class safe.

Agree with this especially if there is wind and little experience in flying

Well, what happens when the AC is flying in GPS and it's toggling between GPS and ATTI because of a weak satellite connection is the drone stutters slightly and unpredictably.  It changes direction randomly and tilts slightly by just a few inches without warning.  The flight isn't as smooth which wouldn't matter in the open, but in close quarters, it's annoying and stressful.  Flying in ATTI resolves that problem and results in a smoother flight.  

The real issue is an inexperienced pilot in a windy cool/cold area, contemplating flying in woods. Seriously! And a crowd around him. Not a good scenario.
Pics and vids in open area and or above trees only in GPS mode would be advisable.

I know it is not easy to refuse a teacher's request, but flight safety is top priority. Leave the chance to the next time until you are more skillful and ready for flying. As for the long time flight, I'll suggest to borrow or rent some batteries from local stores.

Do not use ATTI in a windy environment with trees arround. That is difficult. If you must, then go in a similar place on a widy day and try, how it is like.
You will more likely to decide what to do.
Andy

Don't forget also that RTH could create a mess when flying inside tree area ....

It is advisable to switch of RTH and choose hover or land if below tree-top line !

For GPS to suffer loss of signal - it would have to be a dense tree-cover .... so P-GPS mode I would use to aid stability. Remembering the RTH factor.

Nigel

When I get a chance I'll repost the vid above showing the # of satellites during flight... just for fun...

Here's flying in trees ... screen recording ... P3S but principle is same.



Nigel

Let the bird fly in P-GPS on these windy days.

solentlife Posted at 2017-10-25 02:09For GPS to suffer loss of signal - it would have to be a dense tree-cover .... so P-GPS mode I would use to aid stability.

As promised...

As we can see, most of the flight is in forced ATTI due to lack of minimum satellites, so deliberately trying to use GPS becomes a nuisance in close quarters

My bad...