Boresight/Polarity Switch Function?

[Arendellecita]

It's the switch on top of the flight part of the collective. I can understand the Polarity side, but what does the Boresight side do?

 

 

In the AH-64D Block II Cyclic and Collective HOTAS published by wags, the switch is illustrated as:

Quote

8. Polarity/Boresgiht Switch
     a. B/S. MPNVS growth

 

However, in the DCS: AH-64D Quick Start Manual, the switch is illustrated as:

Quote

Boresight/Polarity.

      • B/S. No function.

 

So, what exactly does this Boresight do? Is it used to boresight the IHADSS during alignment, or MPNVS growth, or no function? And what does the "MPNVS growth" mean?

Thanks!

[kgillers3]

So boresight first. 
 

The aircraft computers know exactly where everything is pointing because it’s hard mounted to the aircraft and then boresighted and those values are saved on the computer. But one thing keeps changing. The pilot. The pilot changes in where they sit, how they wear their helmet, how tall, short etc. but the computer is going to use that for alignment of the pnvs/tads with nvs and acq source, and as the hmd as a sight for targeting. So every time you have to get in the cockpit you have to boresight yourself to the aircraft. 
 

the boresight button, used to be a duplicate button of bs now from the wpns page. So you would set it up look into the bru and push that. I believe it’s a carryover from the a model. But now we use the mpd and the button like the hdd button on the tedac either does nothing or it’s repurposed for something else. 

Edited March 15, 2022 by kgillers3
Typo

[Raptor9]

To clarify, initially in AH-64D's this button position did indeed perform the boresight. However, when AH-64D's were upgraded with the M-TADS, this function was no longer active.

The specific avionics version and year configuration of the DCS AH-64D (Lot 9.1, equipped with MTADS, 2005-2010) is accurate in that this button simply has no function.

[Arendellecita]

15 minutes ago, kgillers3 said:

So boresight first. 
 

The aircraft computers know exactly where everything is pointing because it’s hard mounted to the aircraft and then boresighted and those values are saved on the computer. But one thing keeps changing. The pilot. The pilot changes in where they sit, how they wear their helmet, how tall, short etc. but the computer is going to use that for alignment of the pnvs/tads with nvs and acq source, and ase hmd as a sight for targeting. So every time you have to get in the cockpit you have to boresight yourself to the aircraft. 
 

the boresight button, used to be a duplicate button of bs now from the wpns page. So you would set it up look into the bru and push that. I believe it’s a carryover from the a model. But now we use the mpd and the button like the hdd button on the tedac either does nothing or it’s repurposed for something else. 

Thank you very much for the detailed explanation. So I understand the button no longer boresights the IHADSS on the D model. Would you please also define the "MPNVS Growth" term? I am having a hard time understanding the "growth" in this case, since I am not a native speaker. Does it mean to return the MPNVS to the center position? Thanks in advance!

[Raptor9]

Just now, Arendellecita said:

I am having a hard time understanding the "growth" in this case, since I am not a native speaker.

"Growth" means that there is possible future use of a button or piece of equipment. It refers to "growth in capability or functionality".

[Arendellecita]

4 minutes ago, Raptor9 said:

"Growth" means that there is possible future use of a button or piece of equipment. It refers to "growth in capability or functionality".

Thank you very much, Raptor. I learned a new phrase today! :)

[Dr Zaius]

On 3/15/2022 at 1:45 PM, kgillers3 said:

the boresight button, used to be a duplicate button of bs now from the wpns page. So you would set it up look into the bru and push that. I believe it’s a carryover from the a model. But now we use the mpd and the button like the hdd button on the tedac either does nothing or it’s repurposed for something else. 

 

This explains a lot, thanks

[Assamita]

On 3/15/2022 at 3:09 PM, Raptor9 said:

To clarify, initially in AH-64D's this button position did indeed perform the boresight. However, when AH-64D's were upgraded with the M-TADS, this function was no longer active.

The specific avionics version and year configuration of the DCS AH-64D (Lot 9.1, equipped with MTADS, 2005-2010) is accurate in that this button simply has no function.

Didn't know that, and I was looking for that function in the controls window forever. How do they did it when the upgrade happened? they simply clicked "enter" in the colective's cursor joystick?

Edited June 6, 2023 by Assamita