Flight Path Vector display bugged & incoherent, disappears wrongly . (OB , MT)

[Snappy]

Hi,

the FPV display in the HUD seems very buggy. I do understand that the Viggen does not have a modern HUD with 10 degree segments of pitch ladder, but currently it also displays the FPV in a very incoherent buggy manner. The manual says :
 

"Flight path vector (FPV) Indicates the direction of current flight path vector in a 3-dimensional space in the form of a stylized aircraft symbol. Wings stick out of the circle at the 9 and 3 o’clock positions. The “vertical fin” at 12 o’clock is the airspeed deviation indicator. Level flight is attained with wings of the FPV lined up with the horizon. If the FPV is centered in the gap in the artificial horizon the aircraft is on the commanded course from the navigation system."

There is no mention of any limitation, so I take it, as long as the aircraft's actual flight path is within the HUD area as viewn from the pilots point of view , the FPV should be displayed / visible in the HUD.

To best illustrate the problem you can set up a flight, where you start airborne at a high speed of 550+ kts and take two RB24 or 74 as loadout, ( stay in mode NAV , switch the weapons selector to IR-BB , but don't unsafe the trigger  ( I'll get to why) .

Now pitch up 90 degrees to pure vertical. You will see that the FPV disappears already when passing 30degrees of pitch (as shown on the ADI) 

When you are at 90 degrees pitch up and still have enough forward airspeed , the aircrafts actual flight path is pure vertically upwards, which means, you should see the FPV in the HUD. But you don't  in DCS.

If you unsafe the trigger, you will see the IR missile symbology (just to prove the HUD is technically  able to project something at any pitch attitude) . Now the funny thing is , if you now safe the trigger again, the FPV magically does appear correctly in the HUD.

Very odd. The same also goes for significant pitch down attitudes (where the correct display of the FPV should be even more critical)

I tested this some more. It appears the FPV incorrectly disappears when passing 30 degrees pitch up or down (on the ADI)  and oddly reappears only when the pitch is reduced to 20 degrees up/down approximately. 

With aircraft pitch or more precisely aircraft flight path between 30 and 90 degrees from the horizontal the FPV is wrongly not shown inside  the HUD. With my above "workaround"  you can force it, but it works only until the next time you exceed 30 degrees pitch.

Sorry for the long explanation, I tried to make it understandable and reproducable.

In summary :

the FPV incorrectly incorrectly does NOT show flight path or better put, is not visible despite flight path in HUD FOV between 30 and 90 degrees pitch attitude  approx, when the aircrafts actual flight path is within HUD field of view.

Some pics to illustrate: 1.  Pure vertical and still forward speed for vertical aircraft flight path. (weapon selector in IR BB)

2. unsafed the trigger for RB24/74 , correctly symbology shown, in other words, the HUD is generally able to project .

Now 3rd pic, after putting trigger back to safe, the FPV is now finally  correctly displayed/calculated :

Kind regards,
Snappy

 

Edited May 5, 2023 by Snappy

[MYSE1234]

Not a bug that the HUD symbology is hidden in NAV when the FPV is >±15°, and should be displayed again when it's <±12°.
The bug here is that you can get it to display it anyway.  Pretty sure the manual should say that this is how it works by design.

Edited May 5, 2023 by MYSE1234

[Snappy]

17 minutes ago, MYSE1234 said:

Not a bug that the HUD symbology is hidden in NAV when the FPV is >±15°, and should be displayed again when it's <±12°.
The bug here is that you can get it to display it anyway.  Pretty sure the manual should say that this is how it works by design.

 

Hi Myse, do you have a manual reference for that? I searched for "FPV" and   in the latest beta 2.1 manual, and there are only 3 hits and not one mentions that limitation.

I also read the entire HUD section of the manual and couldn't find that limitation.  Maybe I 'm lookin in the wrong place.

[MYSE1234]

6 minutes ago, Snappy said:

Hi Myse, do you have a manual reference for that? I searched for "FPV" and   in the latest beta 2.1 manual, and there are only 3 hits and not one mentions that limitation.

I also read the entire HUD section of the manual and couldn't find that limitation.  Maybe I 'm lookin in the wrong place.

It's possible it's not mentioned in the DCS manual, just sounds weird if it's not, I've not really read it due to the real ones being available. The actual manuals does say it work this way though.

Edited May 5, 2023 by MYSE1234

[Snappy]

Hmm strange. What does the actual manual say about the behaviour in ANF mode?

[MYSE1234]

Only in NAV and the landing modes it should do this.

[Snappy]

Ok, I just just checked in DCS, in ANF the FPV shows correctly across the entire pitch range.
Sorry for the incorrect bug  report then, but I had only the DCS VIGGEN manual for reference  and it seemed incorrect based on that.

@TOViper maybe this limitation can also be included in the new Viggen DCS manual's HUD section if its still up for edit?

Kind regards,

Snappy

Edited May 5, 2023 by Snappy

[TOViper]

Manual now reads the following:
null

 

Edited May 6, 2023 by TOViper

[Snappy]

 

Thanks a lot @TOViper, that clarifies the behaviour for future Viggen pilots

Edited May 6, 2023 by Snappy