Show optimal heading and speed in ME

[Bankler]

When recovering aircraft IRL, the carrier typically turns into the wind, with a certain angle to generate around 25 kts over the deck, and as little cross wind as possible. The Alt-F9 camera shows the WoD and the cross wind, which is excellent. However, this requires a lot of trial and error, and the camera is not available for mission designers who don't own the SC module. The result is that the community builds a lot of missions with really weird recovery conditions.

My suggestion is that you should see the optimal HDG and Speed for the carrier in the Mission Editor (this obviously changes if you change the mission's wind settings). So it's easy for the mission designer to adjust it accordingly. Don't know that the best UX would be. But maybe just a small text overlay, with the optimal setting, and a little warning sign on a leg if that leg's course deviates from what's normal (more than like 3-4 kts crosswind from stern, or more than 0 kts crosswind from port, or WoD that is less than 20 or more than 30, something like that).

The math around this is not that trivial. Luckily, Mags and Bambi in the Master Arms community have already written a web based tool for it, and the code is open for you to use as reference if needed. Here's the tool:

https://magwo.github.io/carrier-cruise/

https://github.com/magwo/carrier-cruise

 

Edited June 19, 2023 by Bankler

[Nealius]

Hey Bankler, are there any sources for this calculation and removal of crosswind component actually being used IRL? I ask because:

1. The only "source" I could find is a conversation among forum members here.

2. SMEs on the forums stated wind is "down the angled deck" and not at an offset, so I assume (perhaps incorrectly) that means 9 degrees left of BRC.

3. Victory's long-pulled CASE I paper states there is always a crosswind component due to the ships movement. I'm unclear if the 0 crosswind calculated by this app is referring to the same crosswind component, or if it's referring to literal crosswind in relation to the angled deck. 

4. This guide, vetted by a former Hornet driver, states that maximum allowed crosswind component is 7kts, which begs the question why this app only targets 0kts crosswind (if it's referring to crosswind component per item 3).

5. At natural wind speeds lower than 22kts, particularly below 10kts, this calculator shows significant crosswind in relation to the angled deck, which in DCS fouls up the 27-30AoB in the 180 due to those winds pushing you starboard as you turn, causing an overshoot unless you go super wide abeam to compensate, while avoiding excessive bank angles. (Maybe this is a DCS-ism?)

Edited June 20, 2023 by Nealius

[WildBillKelsoe]

I agree. we need also a distinction between magnetic heading and true heading for the ships compass (I assume the ships navigation suite is GPS/GLONASS/INS in addition to the regular magnetic compass not counting mag declination)

[Bankler]

@NealiusThanks for the input. I'll do some digging!

[Tweety777]

19 hours ago, WildBillKelsoe said:

I agree. we need also a distinction between magnetic heading and true heading for the ships compass (I assume the ships navigation suite is GPS/GLONASS/INS in addition to the regular magnetic compass not counting mag declination)

That is a nice thing to notice, however, only the mag declination is not enough. Current amnd wind also have an effect on the difference between compass course and course over ground. Both off course when their not dead ahead or dead astern. Calculating the mag declination is easy and is a fixed value for every certain area (don't blindly use the same value from the Marianas on the Normandy or South Atlantic maps) but calculating the course correction for current and wind is also depending on the speed of the ship itself and might thus be somewhat difficult for someone not trained for navigation.

[WildBillKelsoe]

On 6/21/2023 at 9:59 AM, Tweety777 said:

That is a nice thing to notice, however, only the mag declination is not enough. Current amnd wind also have an effect on the difference between compass course and course over ground. Both off course when their not dead ahead or dead astern. Calculating the mag declination is easy and is a fixed value for every certain area (don't blindly use the same value from the Marianas on the Normandy or South Atlantic maps) but calculating the course correction for current and wind is also depending on the speed of the ship itself and might thus be somewhat difficult for someone not trained for navigation.

Yeah that too lots of variables need to be in the GUI for mission makers

[Nealius]

I might be misunderstanding the mag/true discussion here, but if the ship heading and wind direction in the editor are both in true, then in-mission the change to mag shouldn't cause any significant difference in the angle between ship direction and wind direction, no? E.g. if in the editor BRC is 90 true and wind is 99 true, and mag declination is +10, then in mission the BRC is 100 mag and wind 109 mag, the angle off remains unchanged at 9 degrees.

Or is this in reference to the BRC on the LSO plat cam? I've noticed it sometimes disagrees with both magnetic and true values in the info bar.  

Edited June 28, 2023 by Nealius

[Tweety777]

Hello Nealius,

 

You indeed have misunderstood. Wind and current heading are not at all related to the compass heading. Actually, the heading of the wind and the current alone are useless, we need to know the speed as well, just to be able to make an assumption of what the Course Over Ground will be. This is because the wind and the current can move the ship aside. This means that the Course Over Ground is not at all the course the bow is heading towards. The Course Over Ground is merely a fictional figure that determines where you'll end up. We are only talking about compensating the sideslip due to the elements.

[Nealius]

I don't believe such wind and current effects on the ship are modeled in DCS.

[Bankler]

@Nealius You are correct regarding the ME mag/true. Both wind and heading is in true, so the corresponding difference between those two also holds true in game (but expressed in mag). Just like in your example numbers. 

Tweetys comments about current is indeed interesting. I assume it's correct that a ship would head slightly into the wind to stay on course, just like an aircraft. But I think I agree that it's not modelled in DCS. I did a quick test, with 97 kts crosswind. The sea and deck pitch is crazy, but as far as I can tell, the boat still has its nose in the direction it's travelling, and its wake extends from its 6 o clock position straight out. So currents are probably not modelled, making it a no factor, like you suggested.

---

Regarding the matter at hand (i.e whether the boat tries to compensate to eliminate cross wind or if it just puts the natural wind over the angled deck) it's a tough one. Ziplip (who wrote the carrier guide you linked to) scratched his head. The Navy pilots I have talked to about it seem like they haven't even thought of it. Which makes sense. In their world it probably doesn't matter, since even if the boat can (and tries to) eliminate cross wind completely, many times it can't. Sea lanes, proximity to territorial seas ( <- quoted by Yello) has to be respected. So regardless, they will have to land in small crosswinds. Exactly why that crosswind happens is probably of little interest for them. So from a pilot's point of view, the problem gets academic, and they don't care much (which, again, makes sense).

For Mission Editor purposes, I (personally) think it's interesting. I would love to get in contact with someone who actually have worked with this (i.e deciding which way she's heading). Don't even know who's doing that. I asked Yello if he could refer me to someone, but haven't heard back on it.

Yello's gest guess, was that (quote) a combination of the two are employed and compromises are likely. So most likely, the person (or computer) who decides/suggests the ship course probably has all this figured out, tries to eliminate some/all crosswind, but in the end, so many other factors are involved that it's almost insignificant. 

Edited July 5, 2023 by Bankler

[Tweety777]

Still I feel that I've not made my point fully clear. It's most likely not neccesary since it appears to not be modelled , though the prove delivered here indicates more that the person providing the proof missed the clue then proving wether or not it's modelled. See the image below, it's from aircraft perspective but add the factor current the same way the wind is here and you'll understand what I mean.

[Bankler]

1 hour ago, Tweety777 said:

Still I feel that I've not made my point fully clear. It's most likely not neccesary since it appears to not be modelled , though the prove delivered here indicates more that the person providing the proof missed the clue then proving wether or not it's modelled. See the image below, it's from aircraft perspective but add the factor current the same way the wind is here and you'll understand what I mean.

I think what you say makes sense. I guess I'm just not sure how it relates to the topic. I.e request for an aid in the ME in DCS (where the effect you're talking about isn't a factor) for a good heading and speed on the carrier given a certain wind setting. But yes, I humbly might be missing something.

[=4c=Nikola]

On 6/19/2023 at 4:40 PM, Bankler said:

...The math around this is not that trivial...

I fail to understand how the math around this is not that trivial in the game. It's a basic trig with 2 triangles, like 14yo can calculate it in 2min. 

[Tweety777]

56 minutes ago, Bankler said:

I think what you say makes sense. I guess I'm just not sure how it relates to the topic. I.e request for an aid in the ME in DCS (where the effect you're talking about isn't a factor) for a good heading and speed on the carrier given a certain wind setting. But yes, I humbly might be missing something.

Thanks for your reply, my reply's where a response to WildBillKelsoe about true heading. In case of carrier landings (for some reason I thought we were talking ship navigation) the wind indeed would hardly be a factor for the incoming plane IRL since the ship will be sailing (pretty much) downwind anyway, though the current could certainly play a role in the landing IRL, especailly if the current is around 90 or 270 degrees off the course of the ship. That being said, it will most likely not be a huge difference due to the time it takes for the plane from coming out of the turn and touching down.

13 minutes ago, =4c=Nikola said:

I fail to understand how the math around this is not that trivial in the game. It's a basic trig with 2 triangles, like 14yo can calculate it in 2min. 

Because everything you don't know seems pretty tough to understand until you learned how all about it. That being said, for all among us (like myself) who have enough trouble getting the bird anywehere near any of the 4 wires a little tool to help figure out the best course to fly could make things easier.

[Bankler]

34 minutes ago, =4c=Nikola said:

I fail to understand how the math around this is not that trivial in the game. It's a basic trig with 2 triangles, like 14yo can calculate it in 2min. 

Well, "that trivial" is very much open for interpretation. I'm not saying there is any magic to it. Yes, it's trigonometry. Given the fact that I know absolutely nothing about your understanding of boat ops or math, it's impossible for me to know if you are just relatively clever (smarter than a 14yo) or if you underestimate the problem.

To find out, as a fun game (and also since it could help illustrate the problem to others) you have two minutes to solve this problem (you can use a calculator but not the tool):

The wind comes from 045 at a strength of 7 kts. The angled deck is 9 degrees to the left of the bow (Nimitz style). For an aircraft to perceive zero cross wind in relation to the angled deck when in the groove, which bearing and which speed should the boat set? Present your calculations and the time it took you to solve it.

Edited July 5, 2023 by Bankler

[Tweety777]

5 hours ago, Bankler said:

Regarding the matter at hand (i.e whether the boat tries to compensate to eliminate cross wind or if it just puts the natural wind over the angled deck) it's a tough one. Ziplip (who wrote the carrier guide you linked to) scratched his head. The Navy pilots I have talked to about it seem like they haven't even thought of it. Which makes sense. In their world it probably doesn't matter, since even if the boat can (and tries to) eliminate cross wind completely, many times it can't. Sea lanes, proximity to territorial seas ( <- quoted by Yello) has to be respected. So regardless, they will have to land in small crosswinds. Exactly why that crosswind happens is probably of little interest for them. So from a pilot's point of view, the problem gets academic, and they don't care much (which, again, makes sense).

I missed this part earlier. I think the reason navy pilots don't think about this is because this is the duty of the officer of the watch or some officer on the bridge charged with navigating the ship. You mension sealanes and territorial waters. The problem with this as limitation is that those are pretty much all close to the shore. This is where a carrier is vulnerable and any type of attack. Carriers will try to stay at least a few hundred miles off shore letting the planes do the work of reaching the shore to keep the carrier out of harms way. Since the planes nowadays have ranges above 1000 nm, and basically until the pilot can no longer function properly due to fatigue if you take AAR into account, the dangers of being so close to the shore would most likely not be taken by any carrier. In reality I believe (I'm not in any way into this subject beside documantaries) the carrier will always make sure it can turn into the wind and actually do so when launching and recovering planes.

[dankmaster]

It took me about 15 minutes to wrap my head around constructing the triangle.  The rest is just using a calculator to compute two sines and one arcsin.

 

c = 180 - arcsin (sin(a) * (C/A))
  = 180 - arcsin( sin(9 deg) * (25/7))
  = 180 - arcsin(0.15643 * 3.57143)
  = 180 - 33.97
  = 146.03 degrees

b = 180 degrees - 9 degrees - 146.03 degrees
b = 24.97 degrees

B = A * (sin(b) / sin(a))
  = 7 * (sin(24.97 deg) / sin(9 deg))
  = 7 * (0.4221 / 0.1564)
  = 18.89 kts

The calculated carrier speed is 18.9kts.
If the wind is coming from 045, the recip heading is 45 + 180 = 225 (i.e. direction wind is going)
Now we can calculate the carrier heading as follows: 225 - c = 225 - 146.03 = 79 deg

Edited July 5, 2023 by dankmaster
added triangle diagram

[Nealius]

19 hours ago, Bankler said:

Yello's gest guess, was that (quote) a combination of the two are employed and compromises are likely. So most likely, the person (or computer) who decides/suggests the ship course probably has all this figured out, tries to eliminate some/all crosswind, but in the end, so many other factors are involved that it's almost insignificant. 

This is the feeling I get as well, given the acceptable crosswind limitations mentioned in the documentation. We probably won't get a complete answer until we find someone who actually commanded a carrier.

The only thing I can say for certain from DCS-specific experience is that using such trig to cancel/minimize crosswind component from the ship's movement, e.g. wind 7kts 045 carrier steaming 079, totally FUBARs the groove turn if you fly it by the book. If you take the same conditions and set the carrier heading to 054 the numbers work just fine. And, to be honest, the crosswind component caused by the carrier's movement with heading=(natural wind)+9deg is so minor that going through the process of calculating the best heading is just wasted energy and time IMO. Rather than an optimal heading and speed display, I would like to see a heading marker attached to the waypoint leg so the user can set it as desired without having to bounce between the ruler tool and trial-and-error'ing the waypoint position.

[Tweety777]

3 hours ago, Nealius said:

..., I would like to see a heading marker attached to the waypoint leg so the user can set it as desired without having to bounce between the ruler tool and trial-and-error'ing the waypoint position.

That would be a nice edition along with either an arrow displaying the carriers course or the heading in text right next to the carriers symbol in the F10 map. Now I need to zoom all the way in to see what course the ship is on. Though that is quite off topic here.

[dankmaster]

On 7/6/2023 at 12:17 AM, Nealius said:

The only thing I can say for certain from DCS-specific experience is that using such trig to cancel/minimize crosswind component from the ship's movement, e.g. wind 7kts 045 carrier steaming 079, totally FUBARs the groove turn if you fly it by the book. If you take the same conditions and set the carrier heading to 054 the numbers work just fine. And, to be honest, the crosswind component caused by the carrier's movement with heading=(natural wind)+9deg is so minor that going through the process of calculating the best heading is just wasted energy and time IMO.

If the carrier is heading 054, crosswind would be 8kts on landing which is worse than the natural wind alone.  Not only will this require the pilot to modify their break and groove turns, but as for flying by the book, NATOPS LSO Manual:

Quote

CHAPTER 8: EXTREME WEATHER CONDITION OPERATIONS

8.5 EXCESSIVE WIND-OVER-DECK OPERATIONS
Turbulence and ramp burble increase significantly with RHW values in excess of optimum, resulting in an increased frequency of high landing gear loading.

WARNING

Excessive crosswinds adversely affect recovery operations. If the recovery crosswinds exceed 7 knots, rates of descent 3 to 6 feet per second in excess of those experienced during normal operations can be expected, even with corrective pilot technique.

Shipboard aircraft recovery operations with recovery crosswinds in excess of 7 knots shall be approved by the ship’s commanding officer.

Nobody is expecting the pilot to do the calculations while he's flying, but perhaps someone on the deck brought a calculator with and doesn't think it's wasted time and energy to get the optimal BRC/speed for carrier ops 

[Nealius]

On 7/10/2023 at 1:30 PM, dankmaster said:

If the carrier is heading 054, crosswind would be 8kts on landing which is worse than the natural wind alone.  Not only will this require the pilot to modify their break and groove turns

 I frequently fly with wind 7~12kts 9 degrees left BRC, WoD 25~27kts, and do not have to make any major modifications to my break or groove turns. Doing the "calculations" to put it further than 9 degrees left requires heavily modified break and groove turns, often excessively, in DCS. No idea what real life is like but this is objectively what happens in DCS. 

This pass is by no means perfect, might not even call it good, but aside from banking too aggressively in the 90 and having a horrendous groove time I didn't have to modify my break or groove for this. Natural wind 9deg left of BRC at 6kts. Carrier probably at 21kts since I always set 27kts WoD on my missions. 1.0~1.1nm abeam and mostly 30AoB through the groove. According to the calculator, I should set wind 41deg left of BRC. This would require 1.5+nm abeam to not exceed 30AoB in the bank last time I tried it.

 

Edited July 11, 2023 by Nealius

[dankmaster]

I watched your video, long in the groove but otherwise a great landing.

The point I was trying to make is this: initial to trap took about 2 minutes which is 1620ft of left/right drift for a 8kts crosswind.  Without crosswind, it would be zero.  This 1620ft difference is what I mean by modifications to break and groove turns.

[Nealius]

Thanks.

The only modifications I see required would be an earlier groove turn. Perhaps slightly wider abeam distance. But I understand those are all kosher (I recall up to 1.4 or 1.5nm abeam being allowed).

However, if one were to actually try the calculations done by this app--and it seems like I'm the only one who has since everyone else has only posted theory, though I could be wrong--the crosswind (actual crosswind in relation to the angled deck, not crosswind component from the ship's movement) pushes your aircraft laterally to starboard in the groove turn, guaranteeing an overshoot unless you go wide abeam (perhaps >1.5nm) or bank at 45+ degrees. Really no different than dealing with a crosswind on shore. The theory in this thread isn't matching "reality" as simulated in DCS.

Edited July 12, 2023 by Nealius

[Nealius]

Stumbled upon some definitive proof that fancy trig is not done, and the ship is angled to put natural winds down the angled deck. 

Quote

The model was mounted at a 9 deg yaw in the test section in order to orient the angled runway straight
into the wind, as is standard practice for US Navy aircraft carriers conducting aircraft recovery operations.

The Burble Effect: Superstructure and Flight Deck Effects on Carrier Air Wake, Naval Academy research paper.

Also per LSO NATOPS 00-80T-104, RHW (Recovery Head Wind) should be maintained as close to landing area centerline as possible (p.6-11).