AIRBOSS wind direction is wrong on screen

[Solo_Turk]

In this mission, wind blows to 118. So, on airboss screen it should be 118 or 298(idk which one is used irl, probably "from 298"). However, the screen shows 242. When I turned the ship to 242, crosswind wasn't 0.

 

 

 

airboss wind .trk

[Ramsay]

11 hours ago, Solo_Turk said:

In this mission, wind blows to 118. So, on airboss screen it should be 118 or 298(idk which one is used irl, probably "from 298"). However, the screen shows 242. When I turned the ship to 242, crosswind wasn't 0.

Not sure if everything is reported correctly on the "Airboss's Windspeed/Direction Screen" but neither 118° or 298° is close to the resultant wind across the deck due to the carrier's speed/direction combined with the meteorological wind in the mission.

This diagram might help ?

Comment

ARCTAN (25/13) = ~62° so the wind direction from 242° in DCS is perhaps derived from the "measured ?" landing deck headwind/ crosswind components (and ED are modelling real life rounding errors, instrument limitations or similar ?)

However, the magnitude (14 kts) of the wind doesn't make sense (to my eyes) as (from Pythagoras theorem) the landing deck wind components equal 28 knots i.e.

• √ ( 25² + 13² ) = √ ( 625 + 169 ) = √ ( 794 ) = 28 kts

but perhaps I'm misunderstanding what is being displayed in the bottom left of the Airboss's screen ?

 

Edited Saturday at 10:05 AM by Ramsay
Added comment re: ARCTAN(25/13)=62° and wind magnitude

[Nealius]

Natural wind direction would be 298. 

US Navy procedure is to put wind straight down the angled deck, so BRC would be (natural wind direction)+9. Therefore 307 would be the correct BRC. 

Advanced math not required.

[Ramsay]

14 minutes ago, Nealius said:

Natural wind direction would be 298. 

Is that what is/should be displayed at the Airboss's "station ?

Do you have a real life example/link for US carrier operations you can share ?

[AndyJWest]

I'm fairly certain that DCS uses true north rather than magnetic north as the wind direction datum. Ships heading will be magnetic. This can complicate things.

25 minutes ago, Nealius said:

Natural wind direction would be 298. 

US Navy procedure is to put wind straight down the angled deck, so BRC would be (natural wind direction)+9. Therefore 307 would be the correct BRC. 

Advanced math not required.

Nope. If the ship is moving, you need the natural wind coming from the port side to get the resultant straight down the angle. And yes, math, or experimentation, is required since the correct heading depends on both the wind speed and the speed of the ship.

[Solo_Turk]

+9 degree is a constant value that should be added on the wind direction, in my case, wind from 298 true so 298+9=307 should be ship's true course to have zero crosswind on the deck. So, what is 242 for? it's nonsense .242+9=251 is not going to work either for zero crosswind. I made another track. Turned the ship to 307 true. crosswind became -2 kts. If I turned it to 298, it would be zero. that crosswind value is miscalculated also. It considers ship's true heading, ignores 9 degree angled deck. Or we should ignore that -2 kts crosswind and stay that course. idk tbh. Ship's course showed on the screen is true course btw. As you can see on the info bar at the bottom.

my questions are "what's that wind course?" "how is it calculated on the screen?", "Is it bugged and miscalculated?" "how am I suppose to know what course I should turn the ship to have zero crosswind on landing area?" "Is that crosswind value calculated by ship's true course or angled deck true course?" "If by angled deck's course, isn't that also bugged and miscalculated?"

I made the ship stationary to test that ARCTAN effect it still shows 242.

 

 

airboss wind1 .trk

Edited Saturday at 01:35 PM by Solo_Turk

[Ramsay]

25 minutes ago, Solo_Turk said:

So, what is 242 for?

It's the relative wind across the carrier deck i.e. a helicopter taking off into a hover or flying parallel, would fly 242° at 28 knots to remain stationary relative to the moving carrier.

The relative wind across the deck is dynamic and will change with changes to carrier's speed/direction.
The meteorological wind is usually static (in DCS) and/or slow to change - so matches the mission briefing.

25 minutes ago, Solo_Turk said:

"how am I suppose to know what course I should turn the ship to have zero crosswind on landing area?"

Not sure on the exact maths but I'd turn the carrier into the meteorological wind (305°T) and add a "fudge" factor to compensate for the angled deck, OTOH in DCS I general consider "into the wind" close enough when making missions.

Edited Saturday at 01:48 PM by Ramsay

[Solo_Turk]

what if we don't know the wind direction.yesterday I joined my friends' multiplayer mission and carrier was stationary. I decided to move it at 30kts into the wind. I used that wind course.turned ship to that direction and of course crosswind was still there. that's why I  opened this topic. If the mission had dynamic weather and changing wind speed-direction, what would we do? Sometimes, we plan carrier group to go away from hostile territory without considering wind direction. Then, when the landing event time comes, we have to turn ship into the wind. There must be a way to do that I looked it up but couldn't find anything useful. And there is no information about airboss deck in the supercarrier manual.

[AndyJWest]

If you go to the LSO station (LAlt-F9 is the default I think), the wind speed and angle (relative to the angled deck) are displayed.

Wind 3 degrees to starboard of the angle, at 27 kt:

 

As for the maths to work it out, it's a classic 'solution of a triangle' problem. If I can get my brain in gear, I'll figure out which particular case applies. Alternately, you can draw the relevant vectors to scale, and solve it that way.

[Solo_Turk]

No crosswind on the deck according to lso screen. deck is 166 degree magnetic. aircraft is on course 166. still crabbing left.

 

[AndyJWest]

Wind speed and direction can vary with altitude. 

[Ramsay]

3 hours ago, Solo_Turk said:

If the mission had dynamic weather and changing wind speed-direction, what would we do?

Unfortunately the Relative Wind direction and magnitude on the Airboss's screen doesn't update when changing the carriers speed or direction - so even if you bring the carrier to a full stop, you can't see the meteorological wind across the deck.

Here, I've turned the carrier into the meteorological wind and adjusted the course so the crosswind needle is centered i.e. at 0 kts

 

... this is far from ideal, but I'm at a loss for what else you can do if the briefed wind direction changes and isn't updated in the mission brief (LALT+B).

[Ramsay]

29 minutes ago, AndyJWest said:

Wind speed and direction can vary with altitude.

Yes, in this test mission 12 kts @ 33ft increases to 25 kts @ 1600ft (and I'm guessing the 72 ft deck height is responsible for the increase to 14 kt in DCS).

[AndyJWest]

3 hours ago, Ramsay said:

Yes, in this test mission 12 kts @ 33ft increases to 25 kts @ 1600ft (and I'm guessing the 72 ft deck height is responsible for the increase to 14 kt in DCS).

Yup. The difference in wind speed from sea level to deck height would make any mathematical solution trickier, if one was trying to be exact. In practice, negligible in regard to getting the wind down the deck though.

I'm fairly sure I saw a tool of some sort for doing the calculation graphically somewhere on the forum. Anyone know where it is? If not, I could probably knock one up that at least gave a ballpark estimate for the optimum heading relative to the wind direction.

 

 

 

[buur]

vor 1 Stunde schrieb AndyJWest:

I'm fairly sure I saw a tool of some sort for doing the calculation graphically somewhere on the forum. Anyone know where it is? 

you mean this? https://magwo.github.io/carrier-cruise/

[AndyJWest]

27 minutes ago, buur said:

you mean this? https://magwo.github.io/carrier-cruise/

Don't think that was it, but it looks like it will do the job. Many thanks. 

[Nealius]

People are overthinking the math on the angle of wind. "No crosswind" means natural wind straight down the angled deck's axis. That's it. As long as the carrier is moving there will be axial winds going from right-to-left. This is normal, and is not meant to be canceled out by any fancy math like that calculator on github (or even the airboss script). In fact at lower natural wind speeds those calculators will totally f--k up your groove turn. There are axial wind (crosswind relative the angled deck) allowances up to 7kts, but under normal operations natural wind goes straight down the angled deck^[1][2][3]

As to the rest, here you can see the headings on the Airboss displays appear to be True, not Magnetic. Wind is showing as "to" instead of "from," like in the mission editor wind settings. I suspect this is an error as Western convention for wind is always "from" regardless of aviation or simple civil meteorology. 

If the mission wind changes and it is not reflected in the briefing, then note the "wind bearing," find the reciprocal, add 9. That is the bearing you must set the carrier for recoveries. The "crosswind" display appears to be crosswind relative to BRC, not to the angled deck, though I need to test again to be sure. Depending on natural wind speed you will have a crosswind indicated on that display due to the axial winds caused by the ship's movement, but those should be less than 7kts.

[1] CNATRA P-1211
[2] The Burble Effect: Superstructure and Flight Deck Effects on Carrier Air Wake
[3] Aircraft Carrier Operating Procedures For DCS World 2.5 (which uses CNATRA and NATOPS sources)

Edited 8 hours ago by Nealius

[Ramsay]

21 minutes ago, Nealius said:

Wind is showing as "to" instead of "from," like in the mission editor wind settings.

This is incorrect.

The "Relative Wind" direction shown in the bottom left appears to be calculated at mission start? and won't necessarily be the metrological to/from direction i.e. the OP's mission has a 12 kts wind towards 188°T, yet the Airboss screen shows the direction as 242°

[Solo_Turk]

Before my other tests, I had made wind from 360 and the screen showed that same result which was correct. Then I changed it to different value as 298, wind bearing became nonsense. Crosswind speed is presented relative to BRC, I agree. I couldn't find any other way than turning ship 90 right-left try to catch 0-(-2) crosswind speed with  along wind speed higher than ship's speed If I don't know winds direction in mission editor or whether it is changed during mission. If we know it's easy take reciprocal add 9 degree. But when we don't know or there is a dynamic changing weather, ship must show us, right? and it shows wrong value now that's I am trying to report.

[Nealius]

2 hours ago, Ramsay said:

The "Relative Wind" direction shown in the bottom left appears to be calculated at mission start? and won't necessarily be the metrological to/from direction i.e. the OP's mission has a 12 kts wind towards 188°T, yet the Airboss screen shows the direction as 242°

I set mission wind to 180 "to." Will test with other wind directions.

My question is, though, how is wind changing mid-mission? To my knowledge there is no way to change wind direction/speed mid-mission.

Edited 5 hours ago by Nealius

[Solo_Turk]

There is a dynamic weather option in weather tab but tbh I expect a new dynamic weather system compatible with new cloud,rain and fog system added in the future. current system is very old and nobody uses it.

[Ramsay]

1 hour ago, Nealius said:

My question is, though, how is wind changing mid-mission?

Apparent wind:

Apparent wind is the wind experienced by a moving object, like a sailboat or an aircraft, and is a combination of the true wind and the object's speed and direction.

Relative wind is the direction of the airflow relative to the moving object (carrier), rather than the true wind direction.

Comment:

AFAIK the Airboss screen's "relative wind" direction is only calculated at mission start and doesn't update when changing the carrier's speed/direction or switching to a new player slot.

The magnitude of the Airboss's "relative wind" only considers the metrological wind component (perhaps adjusted for deck height) and doesn't include the additional component due to the carrier's own speed/direction.

1 hour ago, Nealius said:

To my knowledge there is no way to change wind direction/speed mid-mission.

Dynamic weather adds cyclone type weather systems to DCS and metrological wind direction and speed can/will vary with the carrier's location i.e.

Edited 3 hours ago by Ramsay

[Ramsay]

4 hours ago, Nealius said:

Will test with other wind directions.

Just did a quick check - there's nothing fancy (or relative) here, it's just wrong.

• wind to 90° is reported as 270° (correct)
• wind to 118° is reported as 242° (wrong i.e. 118 + 180 = 298)

• wind to 45° is reported as 315° (wrong i.e. 45 + 180 = 225)

Looks like it was pure chance the Airboss's relative wind bearing of 242°  in the OP's mission was in the same quadrant as the actual "relative wind" !!!

Edited 48 minutes ago by Ramsay