F-4E INS alignment duration + nav system question

[JB3DG]

On 1/3/2023 at 5:05 AM, Machalot said:

Does an old stable platform system align in the same time as modern strapdown IMUs?  Isn't it also driven by mission accuracy requirements? 

No it does not. Or rather, part of it does, but that's the part that's dictated by the earth's rotation rate. Simply put, if you were to face north, and spin up a caged level gyro and then uncage it, then wait for an hour, it will be tilted 15 degrees to the left, which is still horizontal relative to where you were an hour ago. This is the principle gyrocompass alignment uses to calculate your true heading, which is critical for navigation performance. Most gyroscopes, whether RLG or mechanical rate gyros, don't have a signal to noise ratio strong enough to immediately calculate your direction relative to true north from the earth's rotation immediately. So by waiting for a few minutes, a definite trend of drift can be established, the longer you wait, the more accurate your average of the signal samples becomes.

With modern RLG systems, the 5-8 minutes is sufficient to level the virtual platform and establish true north. With mechanical gyros, you need an extremely well lubricated system to ensure accuracy for the stabilized platform, which is provided by hot oil. So the Litton LN-3 in the F-4E has an additional warmup period before alignment can begin which waits for the oil in the INS to reach a required temperature before you switch to the alignment phase which adds a few extra minutes and means you can end up waiting a while on a cold day.

On 12/17/2022 at 4:10 PM, Heinlein said:

1. from what I get the phantom don't "align" because it only have simple analogue computer and only require a warmup (3 min I think)
2 unknown. I believe two before the DMAS update. 
3. no idea. Doubtful
4. The phantom don't have a hud. your direction is seen on the nav computer. The phantom only have a simple gunsight similar to the one on the F-5

 

This is the ASN-46 Navigation computer, not the LN-3 INS. The two work together (the INS gets and drives the present position from the nav computer) but the INS is still a separate control panel further forward on the righthand console in the rear cockpit. Note the light on the top far right which says AIR DATA MODE, indicating that without INS input it can still navigate using TAS and AHRS data (you have to manually enter mag var and wind data on those 3 dials on the left).

[Alpha]

On 12/30/2022 at 12:42 PM, JayTSX said:

Probably a bit off topic but:

Can the Hud show a target diamond? Because it kinda sounds like it'll have just a gun piper like the F-5 and no further functionality. I expected something alike an F-14s hud with some information about selected weapon and atleast a target marker for easier intercept.

Given that the F-4 is more suited for intercepting compared to the F-5 it seems logical to add this functionality.

A bit late, but anyway: As pointed out in this thread the F-4 Gunsight (LCOSS) was rather rudimentary compared to later systems and it wasn´t a HUD. In the F-4F (ICE Version) one could  use the LCOSS as a "poor man´s TD Box" as the Sight indicated the position of the aquired Target when in an Air-Air Missile mode and locked to a target (and within the rather small field of view of the LCOSS). As the ICE Changes were mostly radar/ins/databus/weapons computer I imagine the older F-4E to have the same ability, can´t say for sure though.

[Machalot]

14 hours ago, JB3DG said:

Most gyroscopes, whether RLG or mechanical rate gyros, don't have a signal to noise ratio strong enough to immediately calculate your direction relative to true north from the earth's rotation immediately. So by waiting for a few minutes, a definite trend of drift can be established, the longer you wait, the more accurate your average of the signal samples becomes.

With modern RLG systems, the 5-8 minutes is sufficient to level the virtual platform and establish true north. With mechanical gyros, you need an extremely well lubricated system to ensure accuracy for the stabilized platform, which is provided by hot oil. So the Litton LN-3 in the F-4E has an additional warmup period before alignment can begin which waits for the oil in the INS to reach a required temperature before you switch to the alignment phase which adds a few extra minutes and means you can end up waiting a while on a cold day.

Thanks.  That's exactly why I asked. There are a lot of variables and no reason the alignment process would be the same between very different systems with different requirements. 

[Biggus]

15 hours ago, Fromthedeep said:

According to the 10 percent true interview, the ARN-101 required well over 10 minutes to align.

I recall something similar to a stored heading alignment being available.  It will still likely take a few minutes to warm up though.

[JB3DG]

8 hours ago, Biggus said:

I recall something similar to a stored heading alignment being available.  It will still likely take a few minutes to warm up though.

Yes there is a stored heading alignment which is quicker in the alignment phase, although the warmup phase is unaffected.

[Biggus]

I stumbled upon this from the 1F-4E-1.

 

I'm not sure how this would translate into the DCS startup options.  I'd assume a check box in the mission editor for a pre-scramble alignment.

[Machalot]

29 minutes ago, Biggus said:

I stumbled upon this from the 1F-4E-1.

 

I'm not sure how this would translate into the DCS startup options.  I'd assume a check box in the mission editor for a pre-scramble alignment.

Looks like a classic Stored Heading alignment just like we have in the teen series fighters in DCS.

[Lieuie]

Yes. It's the stored heading alignment.

[Cobra847]

On 4/3/2023 at 9:24 AM, WinterH said:

I'm afraid I'l have to pull off the "you'll have to trust me on that one" here. I do recall HB stating a few times that it will DSCG being first, DMAS being later in various forum posts etc, but can't quite dig them out right now :). But yeah, it isn't stated in that FAQ. Really sure they won't be at the same time at release though.

Perhaps @IronMike or @Cobra847 may clarify the order when/if they are able

DSCG first with DMAS to follow, indeed.

[Temetre]

Man, I hope the alignment, using stored, isnt excessively long. The F4 is super interesting to me, but if its like >10m startups every time, then thats a reason not to get a plane. 

Complex startups can be fun and immersive to me, but waiting in front of a screen takes me out of it, so im just wasting time.

Or where I wouldnt mind an unrealistic "fast alignment" (or fast gyro oil warmup lol?) option or so. Thats really the only thing that ever bothered me with DCS level of realism.

Am 30.12.2022 um 15:27 schrieb WinterH:

AFAIR, going by the manuals, DSCG also has some automated bombing modes via an oldie analog bombing computer, but from what I remember it looked like it's almost more trouble than its worth. I recall one CCRP-esque mode that resembled A-4Es bombing computer but more involved, as we had to enter bomb ballistic information too, and a sort of "radar bombing mode" that seemed kind of like a waypoint based thing if I recall correctly.

Afaik the A-4E also has the bomb data entered as well, but its either skipped or done by engineers when the plane is loaded. The LABS computer is reliant on the radar for distancing too. Maybe the F-4 has the WSO (Rio?) enter the data correctly? Probably shouldnt be too complicated though, IIRC someone said it was 2 or 3 factors for each weapon.

Im a bad pilot, but even then using LABS in the A-4E was super easy and quite accurate. Never even used it to toss, just for shallow dives (it does up to 30 degree tho).

Edited April 9, 2023 by Temetre

[Machalot]

1 hour ago, Temetre said:

Or where I wouldnt mind an unrealistic "fast alignment" (or fast gyro oil warmup lol?) option or so. Thats really the only thing that ever bothered me with DCS level of realism.

That's called Hot Start. 

[Temetre]

vor 10 Minuten schrieb Machalot:

That's called Hot Start. 

 

Are you just trolling? Or do you think I dont know what a hot start is?

[Machalot]

7 minutes ago, Temetre said:

 

Are you just trolling? Or do you think I dont know what a hot start is?

Not trolling, just a little cheeky, too much I guess. I don't know your level of experience with DCS.  You said you want unrealism and fast start up.  

[Temetre]

vor 21 Minuten schrieb Machalot:

Not trolling, just a little cheeky, too much I guess. I don't know your level of experience with DCS.  You said you want unrealism and fast start up.  

Fair, I probably overreacted to your comment. I thought it was kinda obivous what Ive been talking about, but maybe not? Because Im not saying that at all, its actually the opposite: INS is the only thing where I ever really want unrealism. Im fine with startups taking some effort, like its in most DCS aircraft. I like the level of simulation. When I fly a mission, even in liberation, I sometimes just like to do startup and shutdown procedures. Its immersive, it can be fun. 

I think the game would lose something if I only ever use hot start on an aircraft.

 

 

So why dont I like INS align? Well, compared to any other thing, youre just stuck waiting for minutes doing nothing. This is actually pretty unique in DCS, because in almost every other situation im under a heavy workload. With INS alignment, it just forces me to do nothing. I mean its probably not hard to see why that can be boring?

And worse, since im going from doing work (like starting the aircraft) to doing nothing for a bit, it takes me out of the immersion. Makes me feel like im sitting in front of a screen, rather than operating and aircraft. The alignment time isnt simulating anything the pilot does, except waiting. Its the same thing as how I dont want to wait 1 hour for a mission to start, which might be the case for a real pilot.

It obviously depends on the aircraft; It doesnt really matter with an F18, where its 1.5 minutes and you can set up computers or whatever. F16 is fine, except when the stored alignment bugs out. But its already worse with the 3 mins or so on an F14, with nothing to do as the pilot. If the F-4 is worse than that, then that would suck a lot.

 

And its not unprecedented for aircraft to have realism-options to account for certain things. Slavishly simulating everything isnt always the best thign to have, so an option can be quite useful (like everything about Jester is utterly unrealistic, but it is a good thing).

You dont need to agree, but you get what Im saying?

Edited April 9, 2023 by Temetre

[Lieuie]

Fast alignment should take approximately 3 minutes according to the manual.

[Temetre]

vor 38 Minuten schrieb Lieuie:

Fast alignment should take approximately 3 minutes according to the manual.

Thanks, that isnt too bad. Actually just seen that its actually in the DMAS manual! 

[Machalot]

22 hours ago, Temetre said:

You dont need to agree, but you get what Im saying?

I don't know.  This seems backward.  If you said you don't care about immersion and you just want to get to the fun part, I might understand even if I value them differently.  But you're literally saying realism in the start up procedure is immersion breaking for you, and you'd rather have the developers create an option for unrealisticly rapid startup to increase your immersion.

Regardless, we're only talking about a few minutes during which you could review your flight plan, set up your radios and avionics, or take a drink of water. In multiplayer you can chat with your buddies and coordinate your plans, and in single player you can even use time acceleration to achieve exactly what you're asking for if it's really that unbearable. I'm guessing your flight to the mission area is much longer than this and often just as boring. I think it's a matter of perspective.

[Alpha]

On 4/9/2023 at 7:41 PM, Temetre said:

So why dont I like INS align? Well, compared to any other thing, youre just stuck waiting for minutes doing nothing. (...)

And worse, since im going from doing work (like starting the aircraft) to doing nothing for a bit, it takes me out of the immersion.

 

While I do understand what you mean that "problem" only occurs because you skip all the stuff that´s done while the INS aligns in real life. I know it´s not really necessary in DCS, but IRL there´s stuff to do while the INS alignment is running. Some of those checks are done in coordination with the crew chief. In the F4 some of the checks are Speedbrake, Flaps/Slats, Flight Controls, Stab Augs, Air Refueling Door, Hook etc.   

 

For example you´d deploy the Flaps, check Elevator Aft/Fwd, Rudder L/R, Aileron Left and hold it there. Then you´d engage the Yaw Aug and (with the help of the Crew Chief) check if the rudder kicks a bit as required. Then you go Aileron neutral and switch off the Yaw Aug. Now you´d do the same with "Aileron right". And so on...

 

I do hope the manual will include all/most of the checks done in real life - there enough so you will initially not be able to squeeze those in while the INS aligns. In other words: the INS will wait for you...       Of course it´s really up to each player if those checks are done - but they are never skipped in real life.

Edited April 11, 2023 by Alpha

[Temetre]

vor 5 Stunden schrieb Alpha:

While I do understand what you mean that "problem" only occurs because you skip all the stuff that´s done while the INS aligns in real life. I know it´s not really necessary in DCS, but IRL there´s stuff to do while the INS alignment is running. Some of those checks are done in coordination with the crew chief. In the F4 some of the checks are Speedbrake, Flaps/Slats, Flight Controls, Stab Augs, Air Refueling Door, Hook etc.   

 

For example you´d deploy the Flaps, check Elevator Aft/Fwd, Rudder L/R, Aileron Left and hold it there. Then you´d engage the Yaw Aug and (with the help of the Crew Chief) check if the rudder kicks a bit as required. Then you go Aileron neutral and switch off the Yaw Aug. Now you´d do the same with "Aileron right". And so on...

 

I do hope the manual will include all/most of the checks done in real life - there enough so you will initially not be able to squeeze those in while the INS aligns. In other words: the INS will wait for you...       Of course it´s really up to each player if those checks are done - but they are never skipped in real life.

I know what you mean, but I dont really enjoy the extensive testing of everything. Its also a matter of time; its hard enough to even understand and correctly use a lot of the normal use systems on certain aircraft. A lot of my flights are half about learning to use systems effectively, as much as its about just using them. When I fly a different aircraft, again theres a "getting used to" period. 

Stuff like that imo goes into roleplay territory (tbf maybe so does engine startup in general), and everyone wants different things. Or heck, people sometimes want heavier and sometimes lighter sessions. It gets even contradictory when you play VR; thats the most immersive way to play flight sims in some ways, but considering how tiring it cane be, you hardly even get to fly till you get headaches or dizzy and have to stop. Skipping some "RP-stuff" is what allows you to have a more immersive experience.

 

But yeah, im kinda brabbling on. Sims like DCS are weird, because they never replace the experience of actually flying the plane. We all set ourselves rules as to how realistic we want to play or not. No matter how detailed the devs want to be, they just cant replicate that experience. 

 

[Temetre]

vor 23 Stunden schrieb Machalot:

I don't know.  This seems backward.  If you said you don't care about immersion and you just want to get to the fun part, I might understand even if I value them differently.  But you're literally saying realism in the start up procedure is immersion breaking for you, and you'd rather have the developers create an option for unrealisticly rapid startup to increase your immersion.

Idk if I should even carry on this, but... yeh, it sounds backwards because you dont get what Im saying. Of course I didnt say that I like realism and thats why I dont want realism, that would be a stupid thing to say. And if I didnt like elements of realism, then I obviously wouldnt play DCS.

I mean, you just need to apply that logic to yourself: So do you have >1 hour briefing and preperation phase every time you do a DCS flight? Do you play every aircraft from a custom made simulator cockpit directly replicating the aircraft model you fly? Did you stop playing flight sims ever again after crashing the first time?

Because if you dont do those things, then you are playing unrealistically, and skip realism to get faster to the fun. How is that different from me not liking elements like overly long INS phases? 

vor 23 Stunden schrieb Machalot:

I think it's a matter of perspective.

Its not even perspective, its preference. Take a step back and look at the shortcuts you like to do, and then consider that Im doing the same. 

Edited April 11, 2023 by Temetre

[Dragon1-1]

1 hour ago, Temetre said:

I mean, you just need to apply that logic to yourself: So do you have >1 hour briefing and preperation phase every time you do a DCS flight? Do you play every aircraft from a custom made simulator cockpit directly replicating the aircraft model you fly? Did you stop playing flight sims ever again after crashing the first time?

Crashes are sometimes survivable.  As for the rest, plenty of people build simpits, and quite a few brief their missions properly, particularly serious MP squadrons. DCS doesn't have a dynamic campaign yet, but in those, planning a mission can approach this level of complexity. It depends on a mission, too, IRL not every mission takes an hour to plan (CAS in particular can be fragged and flow very quickly).

I really wish tests were more useful, but it's all about building good habits. If you get used to doing it right, you won't be doing it wrong if it ever matters.

[Machalot]

1 hour ago, Temetre said:

Idk if I should even carry on this, but... yeh, it sounds backwards because you dont get what Im saying. Of course I didnt say that I like realism and thats why I dont want realism, that would be a stupid thing to say. And if I didnt like elements of realism, then I obviously wouldnt play DCS.

I mean, you just need to apply that logic to yourself: So do you have >1 hour briefing and preperation phase every time you do a DCS flight? Do you play every aircraft from a custom made simulator cockpit directly replicating the aircraft model you fly? Did you stop playing flight sims ever again after crashing the first time?

Because if you dont do those things, then you are playing unrealistically, and skip realism to get faster to the fun. How is that different from me not liking elements like overly long INS phases? 

I'm not criticizing you for wanting to balance some unrealism with fun. I'm saying I don't *understand* your statement that realism on the INS breaks your immersion. 

1 hour ago, Temetre said:

Its not even perspective, its preference. Take a step back and look at the shortcuts you like to do, and then consider that Im doing the same. 

I'm also trying to provide suggestions on how to relieve your boredom while waiting for the alignment.  And how other aspects of the play experience might be viewed as similarly "boring" depending on your perspective, but we all find ways to play through.

[Temetre]

vor 2 Stunden schrieb Machalot:

I'm not criticizing you for wanting to balance some unrealism with fun. I'm saying I don't *understand* your statement that realism on the INS breaks your immersion. 

I'm also trying to provide suggestions on how to relieve your boredom while waiting for the alignment.  And how other aspects of the play experience might be viewed as similarly "boring" depending on your perspective, but we all find ways to play through.

Idk, you dont get what Im saying. But its not a big deal either.

[RevampedGrunt]

I wonder if tests will be more useful with the F-4 with how the dynamic wear for components could possibly be done. If it's saved between missions or even in MP servers where you do a lot of landing and start ups again, may want to make sure the aircraft is still functional. Not sure if it'll be something that goes beyond just repairing the aircraft with the ground crew but it'll be very interesting to see how it plays out.