The dev working on the HUD made some posts pertaining to seemingly peculiar behavior with regards to the gun sight. I’d noticed it but wasn’t sure of what was happening. It’s fascinating. He’s referencing the video I posted above.
I’m working on the F-14 HUD (i.a.) for Heatblur DCS F-14A/B. I’ve watched and re-watched this video a bunch of times in the past (among many others of course). There is an interesting little detail going on in this video which I think is worth pointing out: if you look from 3m58 or so onwards, the target diamond seems to be off the target, and then at 4m07 he seems to get a sidewinder lock and the target diamond is suddenly on target. At first glance it looks weird, almost like the target diamond is inaccurate or something. The explanation is as follows: he has a radar STT lock while in guns mode, but he is in RTGS (real time gunsight) mode. In this mode the target diamond shows a 1000foot gun solution instead of the radar STT track… The movable reticle (big plus symbol) shows a solution at target range if below 4000 feet, or 4000 feet if target range is greater. Then at 4m07 he switches to sidewinder (with the weapon selector on the stick, not shown in the video here), and because he already has an STT lock, the sidewinder seeker immediately slaves to the STT direction and thus immediately has lock. In sidewinder mode, as in most other modes aside from RTGS guns, the target diamond shows the radar STT location, and therefore suddenly jumps to the target.
With regards to the HUD refresh rate.
Part of it is different sensor update and computation rates, but another part is this: the HUD is a vector (a.k.a. calligraphic) display, like 1980s Asteroids and Battlezone arcade games. These displays have a unique property that raster (pixel grid) displays do not have: the more elements that are shown (i.e. more vectors in the display buffer), the slower the overall refresh rate, since it cycles through all the vectors to draw them. Conversely, when showing fewer elements, the update is much more frequent and appears smoother. The upside of a vector display is that it in effect has much better resolution than a raster display (of the era). The VDI (loosely known as the “heads down display”) in the F-14 is also interesting in that it is a hybrid of vector and raster, some elements are displayed as vectors and others as (pretty low resolution) raster images. These days (well, for the past 25-30 years probably) raster display resolution is good enough that vector displays have gone completely out of fashion, I don’t think anything modern uses them anymore. Most people now don’t even know such a thing ever existed