What is that top right HUD boresight

[DmitriKozlowsky]

Is that a purely optical MK1 sight in case of everything fail? Kind of like Maverick boresight in Viggen.

[fmedges]

It’s to align the seat height with your eye level and the hud.

Edited June 12, 2020 by fmedges

[Tholozor]

It's a boresight alignment cross for the pilot to align the JHMCS.

Edited June 12, 2020 by Tholozor

[shu77]

Yeah the Chucks guide says its to align the HMD

[Swift.]

I'm not 100% but I'm fairly certain JHMCS alignment is done with a projected cross on the HUD glass itself and not with the black circles. What I've heard is that the black circles are for ground crew use in collimating the HUD.

[Fri13]

It's a boresight alignment cross for the pilot to align the JHMCS.

 

The JHMCS is aligned not by using that, as it is for backup gun sight.

The JHMCS alignment is done with the HUD symbols. You get there various positions and patterns that you use to calibrate it.

 

There is NATOPS about the JHMCS calibration and alignment procedure. As well there are different research for the various physiological problems that are caused by JHMCS calibrated slightly wrong.

In the dual-seaters the rear-seater that can as well have a JHMCS and that can designate targets separately, has a own dedicated device in place of the HUD that generates the symbols.

 

2.21.12 JHMCS Alignment.

The JHMCS must be boresighted (aligned) with the aircraft prior to

every flight. Selecting the ALIGN (PB 20) option on the HMD format boxes ALIGN, selects coarse

alignment mode, and displays the FINE (PB 1) alignment option after the coarse align function is

complete. See figure 2-56.

The forward and aft helmets are aligned independently. The ALIGN option on the HMD format at

PB 20, when selected from the aft cockpit, initiates aft HMD align. When in aft coarse or fine align

mode the MC assigns the right AFT hand controller Designator Control (DC) switch to the HMD

format. Both forward and aft HMD alignments function the same with the exception that the aft

helmet is aligned to the BRU mounted on the aft main instrument panel.

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.

The WSO moves the HMD to superimpose the alignment cross on the HMD over the alignment

cross on the BRU, figure 2-56, sheet 2. Once aligned, the undesignate switch on the right hand

controller 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.

 

2.21.12.2 FINE Alignment.

When the FINE (PB 1) option is boxed an alignment cross is displayed

in the HUD and two alignment crosses are displayed on the HMD in the vicinity of the HUD alignment

is indicated (FA DXDY), the pilot moves the TDC either left or right to align in azimuth, up or down

to align in elevation. The pilot presses and releases the cage/uncage switch when satisfied with the

quality of the azimuth and elevation alignment. This causes the display to toggle to roll alignment

mode. With the roll axis indicated (FA DROLL), TDC inputs to the left or right are used to rotate the

HMD alignment symbols to align with the HUD alignment cross. The pilot presses and releases the

cage/uncage switch when satisfied with the quality of the roll alignment. Pressing and releasing the

cage/uncage switch continues to toggle between these two modes until the pilot deselects FINE to

return to coarse alignment or exits alignment.

Upon entering fine alignment, automatically, or if commanded by the WSO selecting the FINE

option, the EU indicates which axis is being aligned. If the azimuth and elevation axis is indicated, the

WSO uses the DC to move the crosses up/down and left/right to align with the cross displayed on the

BRU, figure 2-57, sheet 2. When satisfied with the alignment, the WSO presses and releases the

undesignate switch on right hand controller at which time the EU automatically switches to roll

alignment. The WSO uses the DC to rotate the cross so that it aligns with the cross displayed on the

BRU. When satisfied with the quality of the alignment the WSO presses and releases undesignate

switch on right hand controller.

2.21.12.3 Alignment Exit.

Alignment is exited whenever ALIGN is deselected (unboxed), an A/A

weapon is selected, MENU is selected, TDC priority is reassigned, ACM mode is selected, or the master

mode is changed. This removes the alignment cross from the HUD, removes the FINE option, unboxes

ALIGN, and returns the cage/uncage function to the previously assigned system.

 

 

 

 

 

There is more to it, but it is not that top right cross in HUD for it.

 

And it is not for seat height either. You change your seat based your preference. And the JHMCS after calibration automatically adjust to the seat height changes.

 

Nothing denies you from using it for height positioning, but it is nothing more than a boresight cross for electronic unit (EU) malfunction so you can still have a visual designation for targeting systems and shoot with cannon with acceptable prediction accuracy.

 

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Edited June 12, 2020 by Fri13

[Lex Talionis]

Those alignment marks were there long before the helmet was a glimer in engineers eyes. It is to align the combiner glass to eachother and to the VV on the deck.

As said previously, it can be used as a reference for many things outside of its offical use, but those would all be considered techniques .

[Fri13]

Those alignment marks were there long before the helmet was a glimer in engineers eyes. It is to align the combiner glass to eachother and to the VV on the deck.

 

Didn't add all the things, just point out that there are things for HUD that are meant for calibrations. The JHMCS calibration screens are not included there like in NATOPS.

 

 

As said previously, it can be used as a reference for many things outside of its offical use, but those would all be considered techniques .

 

The embedded dark cross in top-right of HUD can not be used for JHMCS calibration, and it doesn't help even in the seat height adjustment as you already see what the HUD can show when you move up and down, as you change your seat altitude for various reasons.

 

It is there only, for backup gunsight and target designation if HUD fails.

 

Sure it can be used to even for anything else as one fantasies, but it is unsuitable for those things.

 

And hopefully we would see misalignment in JHMCS and some other things that would teach players to understand what the crosshair truly is for.

[G B]

Seat eye height. Literally nothing else.

[Browny]

I've done a function check of the JHMCS in the real Hornet and that is done using the DDI and JHMCS symbology.

 

I believe what Fri13 has posted about the JHMCS calibration is correct. If need be I can asked my mates that still work on the Hornets.

 

As for the marks in the top right corner of the HUD I was told by the guys in the Avionics workshop that they are use for the HUD calibration process.