Whats that cross?

Hi, everyone.

Can anyone tell me what the cross with a circle around it is on the hud frame? It's on the right-hand side.

To me, it looks like something you align with the dot on the other side to get seat height adjustment for your own eye height.

Been meaning to ask this for ages and just got around to it. Keeps me awake at night :)

Cheers.

No picture to show us what you are talking about?

Ok, stand by.

AFAIK, for JHMCS alignment

2.21.12.1 Coarse Alignment. An alignment cross is displayed on the HUD/BRU and on the

HMD/AHMD. See figure 2-56. The pilot moves the HMD to superimpose the alignment cross on the

HMD over the alignment cross on the HUD. Once aligned, the cage/uncage switch is pressed and

held until ALIGN OK is displayed on the HMD. When coarse alignment is complete, fine alignment is

automatically selected. Fine alignment (PB 1) can also be manually selected.

Ah, many thanks, mvsgas. Saved me uploading images etc.

Much appreciated.

Makes sense.

In case anyone is interested this is what I was talking about.

It is not necessarily for JHMCS alignment. I know that because all Hornets, from A-D, had it. Pilots said it was for head alignment, which is pretty close and basically the same thing. But it's called the HUD/BRU alignment cross. BRU stands for Boresight Reference Unit.

I know I would try to use it for aiming if my HUD is damaged and I'm still turning with a bandit :D

I know I would try to use it for aiming if my HUD is damaged and I'm still turning with a bandit :D

He he!

It is not necessarily for JHMCS alignment. I know that because all Hornets, from A-D, had it. Pilots said it was for head alignment, which is pretty close and basically the same thing. But it's called the HUD/BRU alignment cross. BRU stands for Boresight Reference Unit.

Ah, ok cheers.

For the unknowledgeable it seems to be an iron sight with the front part of the sight on the other glass pane (as seen on the picture). I wonder if it has multiple purposes?

But I'm just a dummy.

And I thought it was a backup gunsight....

When I worked on them they told us it was for setting the seat height you look through the HUD and adjust the seat height till the dot is in the center of the cross.

When I worked on them they told us it was for setting the seat height you look through the HUD and adjust the seat height till the dot is in the center of the cross.

A lot of airline aircraft have a similar setup. If they use a hud like the Dash 8 Q400. Usually, 2 ball shaped things. :thumbup:

Yeah, as mentioned it is of a couple of uses, but is essentially a fixed "sight" to see where the HUD is aligned - the projected picture actually floats in optical infinity, and follows with you when moving your head around. If you look the HUD so that the cross and the dot are aligned, anything in the projected picture that is supposed to be straight forward is also aligned "behind" these printed marks. It is helpful if anything needs to be set referring to the airplane's axis.

And as mentioned, it is not related to the helmet-mounted display, but found on every frame that I'm aware of, even if not equipped with, or from the era before the helmet-mounted display. To quickly see if an airframe is HMD-compatible, the small square box:

...is for the magnetic field based helmet position sensing.

AFAIK, for JHMCS alignment

Your funny,. Its for normal eye viewing angle.adjust seat height control on left side of ejection seat to line it up.

I thought this cross is for air refueling aligment, not even close, lol... I always learn in this forum :)

Whose doing the plugging?

Like the boom operator? You know, you seem angry about your choices, its ok, we all make mistakes. Lets move on. So why is the cross offset? What are you aligning? I forgot how much fun is inter service rivalry.

Like the boom operator? You know, you seem angry about your choices, its ok, we all make mistakes. Lets move on. So why is the cross offset? What are you aligning?

Head position for HUD viewing as has been mentioned.

But why offset from center?

Would be better a part of the projection, like when they do boresight of the HUD?

I have no idea in actual fact, but to my mind, it's hard written on the glass and not projected so that it is always there, in the event of HUD failure, when a boresight reference would be most useful. Putting it in the centre only makes sense if it was projected, putting it offset and hard coded means it's not in the way when you don't need it, ie HUD functions normally.

You can see backup sights adopted into most combat planes from very early on - something suggestive of what we don't get (or do) much in sims - failure.

Also when setting seat height you may not have the HUD on, it's likely something you do as you get in the pit, like in the same way you adjust your mirrors in your car before driving away.

But why offset from center?

Would be better a part of the projection, like when they do boresight of the HUD?

So does any of it matter within DCS? Do we have to adjust the seat height to center this every time we enter the pit? Or we just center our point of view (like Track IR, etc.)

Can it be turned off?

it's printed on the Glass, not projected.

Yes, and besides being permanent marking, it has no "backup sight" function whatsoever. In an unlikely situation of loosing the HUD while otherwise retaining mission capability, you can reproduce the HUD symbology on either DDI (two upper displays). This is good enough for guided weapons while all but useless for the gun of course.