Gun reticle accuracy and seat height [user problem]

[Rifter]

Perhaps this is useful for F-5 beginners:

When using guns on the F-5 I was always amazed by my poor hit rate and blamed it on my total incompetence.

Lately I played around with air targets and could not even score a hit when I stuck the nose of my F-5 into the engine exit of my target (I'm exaggerating a bit now). Actually the reticle in the HUD always seemed kind of off to me.

Since I never used the seat height adjustment I decided to check whether it influences the accuracy of the gun reticle.

And yes: Putting the seat into a down position suddenly made the guns hit where the reticle points at. I didn't know that! Could not find anything about that in the forum either.

Hence: I'm only playing in VR - so I don't know how the seat height effects the reticle accuracy on pancake.

Edited April 20, 2024 by Rifter
Typo; Solution found

[Tiger-II]

I assume you're using one of the AA modes and not a fixed gun sight?

[Rifter]

Yes, for the gunsight modes, primarily A/A2 against constant rate maneuvering targets. But also for fixed gunsight the reticle depression values of the dive bombing tables suddenly make sense with lowered seat position compared to the default position (maximum up position).
For air to air with fixed gunsight I never bothered because I’ve always chosen my own reference and ignored the reticle.
I don’t know which adjustment height the F-5 incorporates for the seat but in VR it feels like 10cm from top to bottom and taking into account the short distance of the head to the headup display glass I guess 10cm create a noticeable impact for the line of sight.

On a side note: With the pilot body set to visible the seat height adjustment doesn't work at all...probably a bug.

[Rifter]

Found this old thread:

These two pictures show what I realised with the seat height variation: In the first picture it is obvious that the seat is in the most upper position because the guns are visible. In the seat down position the reticle would have pointed a good portion upwards and would have correlated far better to the actual impact point (second picture).

Interestingly within that whole thread no-one took seat height position into account. But to be fair, most of the DCS F-5 pilots find their way around the problem by trial and error and an individual depression setting for the reticle…

[nairb121]

Isn't the reticle collimated, projected to infinity? Unless there's an issue with how that's simulated, seat position should have no effect on the reticle's alignment.

[Rifter]

Yes, a physically build collimator produces an image of parallel light beams which should be perfectly parallel with the longitudinal axis of the aircraft it is aligned with, without any parallax at infinity. Therefore the reticle should be seen at any eye position (at least as long as the eye position is within the volume of collimated light).

That’s why I never bothered about my head position. Initially I started playing around with it in the F-5 because I was so perplexed by the deviation between reticle position and gun hits.

I’m to inconsistent in bombing to safely rule out a placebo effect for the head position (probably it is a placebo effect). But for the calculated AA gun sights it made a difference. Reason might be that the seat height adjustment helps to center the reticle on the headup projection glass. That is not the case with the default height setting. In my case I had the tendency to move my head around to compensate the inconvenient reticle position which can of course imply further inaccuracies during aiming, especially in VR.

Having a nicely centered reticle on the projection glass might be one of the reasons for the seat height adjustment in the first place...

[MadKreator]

On 4/10/2024 at 3:42 PM, Rifter said:

Yes, a physically build collimator produces an image of parallel light beams which should be perfectly parallel with the longitudinal axis of the aircraft it is aligned with, without any parallax at infinity. Therefore the reticle should be seen at any eye position (at least as long as the eye position is within the volume of collimated light).

That’s why I never bothered about my head position. Initially I started playing around with it in the F-5 because I was so perplexed by the deviation between reticle position and gun hits.

I’m to inconsistent in bombing to safely rule out a placebo effect for the head position (probably it is a placebo effect). But for the calculated AA gun sights it made a difference. Reason might be that the seat height adjustment helps to center the reticle on the headup projection glass. That is not the case with the default height setting. In my case I had the tendency to move my head around to compensate the inconvenient reticle position which can of course imply further inaccuracies during aiming, especially in VR.

Having a nicely centered reticle on the projection glass might be one of the reasons for the seat height adjustment in the first place...

This is interesting. I have some difficulties in the f-5 as well. As you mentioned, I’m one who have just delt with “inaccuracies” and trial -and-errored my way to a solution. I wonder if you get the same results adjusting the “pilot head position”( r-ctrl + r-shift + numberpad keys) as using the physical seat height adjustment. If so that would be handy to just r-alt+ numpad 0, to save that view position instead of adjusting the seat height every time. 

[Rifter]

After some additional testing for the A/A1 and A/A2 sights I cannot find any discrepancies with the reticle respectively with the simulated collimator functionality.

I come to the conclusion it is a self-inflicted ergonomic issue. Being to lazy to adjust head position in VR (be it by seat height or head position) I lived with a disadvantageous reticle position (upper border of projection glass) which subsequently led to unnecessary head movements when trying to follow the reticle leaving the projection glass which again led to upper body and therefore right hand movements (=bad for precise maneuvering).

Conclusion:
The not exactly small dispersion of F-5 guns + ignoring basic ergonomics = bad combination.

[Hassle]

In VR, I'm finding the need to sit up taller than usual, hit the VR recentre button (mapped to stick), then "slouch" back down, to get a natural position in the cockpit.

[Rifter]

On 4/15/2024 at 10:21 PM, Hassle said:

In VR, I'm finding the need to sit up taller than usual, hit the VR recentre button (mapped to stick), then "slouch" back down, to get a natural position in the cockpit.

Can't use the numeric keypad for head position because my keyboard doesn't have one. Therefore I'm doing it exactly the same way as you in all other modules. In the F-5 however my default position is quite good with respect to the distance to instrument panel. Just head height is a little to much.