Is Tacking A Viable Solution To An Overpowering Headwind?

[brett8883]

Now you are conflating two completely different things. The aircraft will pitch exactly the same in all conditions unless it is constrained by being unable to hold altitude at those pitch levels. It has nothing to do with the wind.

We have actually talked about this before in a different sense and I still have the flight record I sent you.

FLY746.DAT

drive.google.com

This flight was in fairly windy conditions not high enough to stop the Mavic in its tracks but still fairly high.

If we look at ATTI mode the elevator stick is almost exactly proportional to the aircraft pitch and the max pitch value at full elevator is consistently right around 35 degrees.


If we look at the same thing in Sport mode we see a much different situation. Elevator and pitch are no longer so neatly proportional and the attitude allowed from full elevator forward varied from about 35 degrees to about 12 degrees during an elevator excursion.



You'll also notice that the variable that changes during these excursions is the heading of the aircraft. With the high wind scenario I don't know what other conclusion to come to other than the aircraft is limiting the pitch based on wind.

 

[sar104]

We have actually talked about this before in a different sense and I still have the flight record I sent you.

FLY746.DAT

drive.google.com

This flight was in fairly windy conditions not high enough to stop the Mavic in its tracks but still fairly high.

If we look at ATTI mode the elevator stick is almost exactly proportional to the aircraft pitch and the max pitch value at full elevator is consistently right around 35 degrees.
View attachment 99350

If we look at the same thing in Sport mode we see a much different situation. Elevator and pitch are no longer so neatly proportional and the attitude allowed from full elevator forward varied from about 35 degrees to about 12 degrees during an elevator excursion.

View attachment 99352

You'll also notice that the variable that changes during these excursions is the heading of the aircraft. With the high wind scenario I don't know what other conclusion to come to other than the aircraft is limiting the pitch based on wind.

It's limiting pitch based on ground speed in Sport mode.

 

[Meta4]

Another effective technique is to gain vertical height and then fly forward while descending because the power used to maintain altitude can be used instead for forward progress.

If the aircraft is pitch-limited rather than speed limited, which it may be into a headwind, and if the maximum tilt is set higher than that required for altitude hold, then flying forwards and descending does permit higher forwards airspeed.

Climbing to gain altitude with the intention of flying faster "downhill" is just tacking in the vertical plane.
It's not going to help you overcome a strong headwind at all and will simply waste more battery and expose your drone to strong winds for longer.

Flying forwards while also descending may allow for a slightly higher airspeed because you are adding a small vertical component to the same horizontal component.
But that slight increase in airspeed does not provide any increase in the speed over the ground, which is the speed that is important.

Factor in the added battery drawdown from climbing and the likelihood of encountering even stronger winds at height and it's obvious that this is not a strategy to bring your drone home in a strong wind situation.

It's very simple to confirm with flight test.
Or here's the relevant data from a couple of test runs I just made.

Dropbox

www.dropbox.com

 

[sar104]

Climbing to gain altitude with the intention of flying faster "downhill" is just tacking in the vertical plane.
It's not going to help you overcome a strong headwind at all and will simply waste more battery and expose your drone to strong winds for longer.

Flying forwards while also descending may allow for a slightly higher airspeed because you are adding a small vertical component to the same horizontal component.
But that slight increase in airspeed does not provide any increase in the speed over the ground, which is the speed that is important.

Factor in the added battery drawdown from climbing and the likelihood of encountering even stronger winds at height and it's obvious that this is not a strategy to bring your drone home in a strong wind situation.

It's very simple to confirm with flight test.
Or here's the relevant data from a couple of test runs I just made.

Dropbox

www.dropbox.com

Agreed - if you don't have the altitude to spare to begin with then climbing isn't going to help at all. I was only addressing the issue of descending with forward motion.

 

[Cymruflyer]

There's only a couple of instances where "tacking" (actually referred to as "S - turns") might be used in aviation - and it's all about going slower! When you are too close to an aircraft ahead, say on final, or that aircraft has delayed clearing the runway, S-turns might be used in slowing your effective approach speed. The aircraft can't otherwise be slowed up much while still going straight, as it's already typically slowed to a fairly small margin over stall speed (1.3 times Vs0, or stalling speed in landing config.). Another time it might be used, is if the aircraft on final is too high on approach - instead of going around and trying again.

It can only be called "S" turns in aviation and never associated with tacking which is only on water, since those two words have completely different meanings and do not relate to one another in any way shape or form. You can not tack in an aircraft but you can tack and do S turns in a sail boat. S turns in a sail boat could be used when you are lining up to start a race and are getting too close to the start line but still have time to go, before the start. In such a situation you would then begin S turns prior to crossing the start line of course, to increase the time it will take for your boat to get to the start line, before the bang to get on with the race. Done just right you are only a few feet behind the start line as the cannon goes off to start the race.

 

[Deleted member 114292]

If a boat was up against A strong current would tacking help it make headway against the current?

No because the whole boat is in the current and will be moving along with the current no matter which direction it’s pointed in.

The aircraft is in the body of air Which like the water is all moving together with the aircraft in it.

 

[raymacke]

I used a similar description in a different thread but was met with skepticism. -

Think of it this way. You are swimming upstream in a river. The current is moving exactly as fast as you can swim. Would zig-zagging back and forth diagonal to the current allow you to make any headway? No, in fact, you would be pushed downstream. Stop tacking and swim straight and you would at least hold your position.

 

[Flynz]

No need to comment on zigzagging, that's been addressed already.

If that was true, you would be able to fly forward while descending faster than you can fly straight and level.
It's pretty easy to test to see how that works out.
And gaining altitude to do that is not going to work out well.

Actually descending while flying forward can increase your airspeed in a fixed wing aircraft or chopper and theoretically ground speed. That assumes that it is possible for the drone to increase its airspeed, which may not work. In any case it is a zero sum game as you consume batteries to climb and risk increased wind speeds.

 

[Flynz]

If you zig zag in consistent conditions then you are reducing your chances of a safe return. It is like trying to fly up the long side of a triangle rather than the short side. You will burn up batteries to go side ways, rather than forward. Your ground speed might increase, but in the wrong direction. Your upwind ground speed will decrease (hypotenuse is the square root of the sum of the sides squared.)

Of course the unpredictable thing is that wind is not even in either direction or strength. Any sailor will be used to scanning the water for lifts, areas where the wind is stronger and avoiding lulls. So changing course could see you finding a lull. Bit of a gamble.

I use sports mode to defeat winds. If that does does not work you can try to find shelter behind an object. For example fly along a line of trees etc. However if you can not make progress against the wind in sports mode then best look for a safe place to land and start walking.

I fly over the sea a lot and there is seldom no wind, so planning is essential.

 

[Meta4]

Actually descending while flying forward can increase your airspeed in a fixed wing aircraft or chopper and theoretically ground speed.

It doesn't increase groundspeed as demonstrated by the sample spreadsheet data I included in post #23.

 

[dougiefresh27]

The best solution is to not get in those situations
but when it does happen
find an altitude with the lowest wind velocity and go into sport mode and hit it hard
if your battery is dying or you are going backwards
find the best place to land and go find your drone
Better than being blown miles away or getting stuck in a tree

 

[dragonmuzz]

Yup..... I tested this when I first got the min.i..im a veteran DJI drone pilot and hoped my experience would help if the drone struggled.... It did.. 2mph in sport mode.. I tried my usual tacking method and got the speed up to over 10mph..enough to get drone back and safely land.. Now I would never fly in that wind to start with but its good to know its possible

 

[dragonmuzz]

Sorry but your wrong and I've proved that

No .. tacking won't help you make headway against a strong headwind.
It will make your drone travel twice as far and expose it to the wind for a lot longer.

Sailboats don't tack to deal with strong winds.
They tack because they cannot sail directly into even the lightest winds.
They also have no battery limitations.

If you put your drone into a situation where it cannot fight against a strong headwind to come home, your only option is to get the drone down low and out of that strong wind.
Too often the battle is already lost by the time flyers realise the problem.
The most effective solution is prevention.

 

[Deleted member 114292]

Sorry but your wrong and I've proved that

Lol

 

[dragonmuzz]

Not funny mate.... See my post.. It works.. Been using that method for years flying rc aircraft and drones.. Its a well documented method for drone recovery in high winds..

 

[sar104]

Yup..... I tested this when I first got the min.i..im a veteran DJI drone pilot and hoped my experience would help if the drone struggled.... It did.. 2mph in sport mode.. I tried my usual tacking method and got the speed up to over 10mph..enough to get drone back and safely land.. Now I would never fly in that wind to start with but its good to know its possible

If you managed to return by "tacking" then you would have been able to return directly, and so that proves nothing. In those conditions the fact that the aircraft went faster is more than offset by it having to travel further in a zig-zag path.

 

[Meta4]

Yup..... I tested this when I first got the min.i..im a veteran DJI drone pilot and hoped my experience would help if the drone struggled.... It did.. 2mph in sport mode.. I tried my usual tacking method and got the speed up to over 10mph..enough to get drone back and safely land.. Now I would never fly in that wind to start with but its good to know its possible

Except it isn't.
By avoiding flying directly against the wind your speed increased ... but it was not taking you anywhere near where you wanted to go.
If you were a sailor you'd want to see the VMG (velocity made good) rather than the instantaneous speed over the ground.

If it's all too complicated, think about the concept that's simply explained in post #27.
If you can't make headway swimming against the current, swimming a zigzag pattern won't help you.

 

[bzmot]

The question has come up in a different thread about using tacking (zig-zagging diagonally to the wind) as a workable solution when faced with an overpowering headwind. This works with sailboats but will it work with a drone or aircraft?

Some years ago I was flying over a salt pan in the area of the Mojave desert and got into some pretty strong winds. Mavic Air, my first drone, and only a few hours of flight under my belt then. I had no idea what I was doing. I merrily flew downwind a thousand feet or so and then found the drone struggling to get back to me. "Maximum motor speed reached" kept flashing. I panicked a little but from my sailing times tacking came to mind. So I tried that, I had nothing to lose anyway. It worked. I had 20% battery when I landed, happy as a clam. Now I know I could have probably recovered it even if it had landed somewhere in the pan but back then it was so stressful. So yeah, for me it was possible. YMMV.

 

[sar104]

Some years ago I was flying over a salt pan in the area of the Mojave desert and got into some pretty strong winds. Mavic Air, my first drone, and only a few hours of flight under my belt then. I had no idea what I was doing. I merrily flew downwind a thousand feet or so and then found the drone struggling to get back to me. "Maximum motor speed reached" kept flashing. I panicked a little but from my sailing times tacking came to mind. So I tried that, I had nothing to lose anyway. It worked. I had 20% battery when I landed, happy as a clam. Now I know I could have probably recovered it even if it had landed somewhere in the pan but back then it was so stressful. So yeah, for me it was possible. YMMV.

No. Undocumented anecdotes of getting somewhere by zig-zagging do not change the fact that tacking is physically impossible in a single fluid medium. It's not a matter of opinion, or "YMMV" or anything else - it's physically nonsensical. There is no such mechanism. It cannot happen.

 

[bzmot]

No. Undocumented anecdotes of getting somewhere by zig-zagging do not change the fact that tacking is physically impossible in a single fluid medium. It's not a matter of opinion, or "YMMV" or anything else - it's physically nonsensical. There is no such mechanism. It cannot happen.

I understand what you’re saying but you weren’t there. When I flew directly into the wind, it just wouldn’t move. At maximum speed the drone was just hovering against the wind. Yet by tacking I got it back. Don’t know what else to tell you.