HUD inaccuracies

[Fox One]

I will try to describe a few HUD inaccuracies that I noticed.

 

The most obvious - look at the screenshot below. Such a display is not possible in the real aircraft. The gap in the middle of pitch bars is always centered on the velocity vector. This can be clearly seen in the well known HUD video where the pilot performs all sorts of aerobatics

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Also, currently in the simulator if the AoA is large enough, the velocity vector will disappear from the HUD. This is inaccurate. There is a limit on the bottom of the HUD, and once the velocity vector reaches the limit, it will stay at the bottom of the HUD, not disappear entirely. This is also well visible in the same video. There are also limits on the sides of the HUD and even above. Simply put, the velocity vector can't disappear from the HUD, no matter what you do. This is not something of no importance. Imagine if the current HUD in simulator will have pitch bars centered on the velocity vector as I described above. Banking the aircraft 90deg and creating a large AoA and the velocity vector will disappear form HUD, and with it also the pitch bars, and you will be left with no attitude info on HUD.

[Fox One]

This is an inaccuracy I noticed even before performing the first takeoff. In the first screenshot below I am flying horizontally only a few feet above water. Being so low, the horizon line should be perfectly overimposed on the natural horizon. But actually it is depressed slightly below the horizon. Flying horizontally and at the same time having the velovity vector pointed downwards at the water are obviously mutually exclusive things. The error in horizon line depression is not large, it is approximately a quarter of deg. Seems like some sort of calibration problem. I am not sure if to solve this all HUD simbology should be raised higher a quarter of deg or the problem is actually more complex.

 

In the second screenshot, F-15 HUD correctly overimposing horizon line on the natural horizon.

[OnlyforDCS]

For your second post. There are mountains in the distance, which is why you feel that the horizon bar is inaccurate. I don't know how it operates in the real plane but I assume that it is in fact accurate and points towards a horizon at 0 m altitude disregarding any elevation in the terrain.

[PiedDroit]

For your second post. There are mountains in the distance, which is why you feel that the horizon bar is inaccurate. I don't know how it operates in the real plane but I assume that it is in fact accurate and points towards a horizon at 0 m altitude disregarding any elevation in the terrain.

 

in the manual it is explained that the hud horizon is always at the same altitude as the A/C, so putting the FPM on the HUD horizon should always result in flying level.

[Fox One]

For your second post. There are mountains in the distance, which is why you feel that the horizon bar is inaccurate. I don't know how it operates in the real plane but I assume that it is in fact accurate and points towards a horizon at 0 m altitude disregarding any elevation in the terrain.

 

What mountains? All there is there is the Black Sea. I deliberately flew above sea, heading 270 so there would be no terrain in front of the aircraft, only sea. All the terrain you see there is hundreds of Km away ;)

 

Besides, I'm not sure you have compared the two screenshots and understood what I'm trying to explain.

[Fox One]

HUD in "Approach" mode. Compared to the simulator:

 

- there are two small lines at -2.5deg pitch to aid the pilot during approach by overimposing those at the end of the runway

- radar altitude below velocity vector also has an "H", though this is pretty inimportant. If the AoA gets too high and the velocity vector gets lower, the radar altitude will be limited to the bottom of the HUD and will not disappear (behaves similarly to the velocity vector as I described in post #1)

- after touchdown the inverted T symbol from takeoff reappears, to aid the pilot in judging pitch angle for aerobraking

- after touchdown the speed, heading scale and altitude will jump back to their undepressed position. However, compared to the simulator, between the undepressed and depressed position there is a 6.5 deg angle in pitch. Currently, in the simulator the depressed position is not low enough

- in the penultimate frame, for a fraction of a second the longitudinal G disappears and the pull up arrow and track error symbol appears. Probably one main wheel hit a small bump, and the weight-on-wheels switch on the shock absorber momentarily opened, and for a moment the aircraft thought that it was still in the air

- I wonder what N/S PTY on the left of the HUD is?

[jojo]

First point: The - - has to be defined in INS, not available right now.

[Fox One]

^^^ Didn't knew that. I thought the lines appear automatically for landing, like on F-16

[jojo]

^^^ Didn't knew that. I thought the lines appear automatically for landing, like on F-16

 

Some airfields have special glide slope approach procedure, so you can customize...equipment is almost as good as a Falcon Bizjet for IFR :lol:

[Fox One]

A/G guns. This mode also uses depressed position for speed/heading/altitude. The pipper is of the same type as for A/A guns, radar tracking. Besides range below radar altitude, range is also displayed in the reticle itself. I believe the full circle corresponds to 2NM.

[Fox One]

About various values displayed on the HUD. In RL altitude and radar altitude are displayed with 10ft increment, not 1ft like in the simulator. 1ft increment is unrealistic, unnecessary and annoying.

 

On real aircraft G meter on HUD shows value with single decimals, and that is more than adequate.

 

When speed is below 100kts, there is no zero in front of the value. Two digits only.

 

When Mach is greater than 0.6 the value appears below speed, and when decreasing below 0.6 it should disappear. Currently in simulator it appears correctly at 0.6, but then it remains on even at below 0.6.

 

Radar altimeter should disappear from HUD at pitch angles of more than 30deg. This is clearly visible in the video in post #1.

[SCU]

 

Also this video shows that the acceleration/deceleration carret has no limit in the HUD, it can go down (or up) to the point that it disappears depending (seemingly) on the amount of deceleration/acceleration. In the sim it can only go so far from the VVI.

[Fox One]

A lot of interesting stuff can be seen in the videos here http://forums.eagle.ru/showpost.php?p=2619418&postcount=129

 

 

See the picture below. First, in AA guns-no radar track, speed and altitude should be in the depressed position, unlike current simulator version. In the second frame, it is still in AA guns-no radar track, however it also has a Magic reticle on the target, something impossible in the sim.

 

The Ka -50 reticle (:D) in the sim that appears when you flip a switch on the HUD should probably look like the large W you see in all 4 frames below. This W is obviously not the fuselage reference line, as it is well below the "cross". I'm not sure about the exact purpose of this W, it appears to be placed at close to the missile boresight reference circle. Some sort of missiles reference line?

 

In frame 3, inside the circle there is another tiny circle - the steering dot :)

 

In frame 4 this small circle has moved to the left outside of the circle. Below the large circle in frames 3 and 4 there is a number - I believe this is target aspect. In frame 4 the target designator on the HUD momentarily changes from square to a triangle, then (if you watch the video) back to square. I believe the change to triangle is meant to warn the pilot that the target aspect is approaching 90 deg and lock lost is likely.

 

IMO, carefully studying the videos, a lot of stuff can be figured and implemented quite accurately. That is, if the developer is willing to make the effort. Because there are always pitch bars on the HUD, the angular dimension of everything and the precise location of everything can be measured reasonably accurately.

[jaguara5]

Also, some times, under the heading scale there is a second triangle (uper right photo) with a changing Number below it or a single triangle with a number. What is this?

And when is there a triangle around the target and not a circle or a box?

Edited December 31, 2015 by jaguara5

[rrohde]

Would be nice if the devs could tweak the HUD to match reality a tad more... :)

[Fox One]

Also, some times, under the heading scale there is a second triangle (uper right photo) with a changing Number below it or a single triangle with a number. What is this?

That is the bearing of the currently selected waypoint. When the difference between current heading and this bearing is higher than a certain value it appears, and at an even higher value it starts blinking.

 

And when is there a triangle around the target and not a circle or a box?

 

My best guess is in post #13

[Fox One]

Also the inverted T at takeoff showing how much the aircraft has to be rotated currently is at -11deg pitch angle. I made some measurements on the video in post #1 and I got -11.75deg. As this aircraft has no flaps, takeoff speeds are quite high. With 3 fuel tanks and rotating to 11deg you get airborne at about 400Km/h. A higher AoA at takeoff is a good thing.

[jaguara5]

Another video. Most of the time the target is in a triangle.

 

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[Fox One]

^^^ I think in the video target designator is a triangle because the radar was being jammed (see ECM TX continuously blinking).

 

IMO, the designator changes to a triangle as a warning that lock might be lost, either due to ECM or due to target aspect angle close to 90deg (as I described in post #13).

 

Also in all HUD videos I could find showing takeoff, air combat, landing I haven't yet seen a video where AoA is displayed on HUD like in simulator.

[VTJS17_Fire]

On real aircraft G meter on HUD shows value with single decimals, and that is more than adequate.

I already wondered, why there is no G meter in NAV mode on the HUD. The Eagle has it, too - and is over 10 years older.

[Fox One]

I already wondered, why there is no G meter in NAV mode on the HUD. The Eagle has it, too - and is over 10 years older.

The truth is, in all videos in nav mode there is no G meter on the HUD. It only appears when you select any A/A or A/G mode.

[jaguara5]

Another observation (from the video with the 530 symbology).

When the target's distance drops to / below 1,9 miles and magics are selected, the distance on the

range scale changes to meters (34 - 3400m) and the caret moves immediate up

Edited January 3, 2016 by jaguara5

[jaguara5]

When 530 selected, targets range remains in nm.

Edited February 3, 2016 by jaguara5

[jaguara5]

Also, with guns selected and a radar lock,

there is no scale range, the distance is displayed only

with the counter clockwise moving pipper circle. (1200m at the 12' position, 900m at 9', 600m at 6' and 300m at 3').

Only the closure speed is displayed in a box

Edited January 22, 2016 by jaguara5

[Manuel_108]

Man, if the developers would respond/implement these small changes I'd buy their plane in a heartbeat. I'm just not sure if they are eager to make their module realistic and up to DCS standards.