Topper81 Posted August 21, 2021 Share Posted August 21, 2021 (edited) Steps to reproduce: - Activate TACAN before catapult launch - Enter for the TACAN course the heading of the aircraft (214°) - Note that there is a straight line in the HSI as expected - Activate the catapult launch - As soon as the aircraft moves, press pause Observed behaviour - Note that the line is not straight anymore, even if the heading of the aircraft has not changed? HSI_CRS_HEADING.trk Edited August 21, 2021 by Topper81 Link to comment Share on other sites More sharing options...
rob10 Posted August 21, 2021 Share Posted August 21, 2021 (edited) What I see is that after you start moving, the little diamond indicator (which is your ground track pointer -- i.e. the direction you're moving relative to the earth) changes to match your actual movement. Since the cat run is offset slightly from the direction of travel of the carrier (i.e. it's not perfectly parallel to the course the carrier is traveling), once you start moving the diamond changes from 214 deg (where the ship is heading) to your actual course (which looks like about 210). In the first pics, since you're stationary, you are traveling exactly the same course as the carrier (it only cares about your actual motion, not where your nose is pointed), so it matches up with the 214 deg that the carrier is traveling at. Not sure what the ribbon across the bottom takes it data from, but I would say the HSI is more likely correct than it. Edited August 21, 2021 by rob10 1 1 Link to comment Share on other sites More sharing options...
Frederf Posted August 21, 2021 Share Posted August 21, 2021 (edited) The airplane magnetic heading is not 214°. That is the airplane true heading. Since almost all of the airplane systems are referencing magnetic North the relationship between true heading and TACAN magnetic course is meaningless. A vertical orientation for the CSEL on the HSI in my test mission is 350° despite my airplane true heading of 352°. That's because vertical on the HSI is the ground track of 350°M (CV track is 356°T). The #1 catapult is angled to the left about 4 degrees. I think there is an issue with HSI display. The lubber line should always be at the 12 o'clock position and the airplane heading read against it. The ground track should vary in angle on the display, not heading. A constant heading launch should not rotate the displayed compass rose on the HSI and by extension the orientation angle of the CSEL line should also not change. There is a bug but it has nothing to do with TACAN directly. Since the HSI is oriented "track up" that means the 12 o'clock position on the HSI is where you're going, not pointed. During catapult launch your track will change and it's normal for your HSI orientation (and thus CSEL line orientation) to change. Makes you wonder why they have a "track pointer" in track up orientation since that's always just going to be 12 o'clock on the display. Edited August 21, 2021 by Frederf 1 Link to comment Share on other sites More sharing options...
Ramsay Posted August 21, 2021 Share Posted August 21, 2021 (edited) 3 hours ago, Topper81 said: Enter for the TACAN course the heading of the aircraft (214°) This is not the heading of the aircraft. Syria, 2016 MagVar = +5°E [from HSI>Data>A/C] • The Super Carrier is travelling 220°T (215°M) [from F10 map, external info bar] • On the catapult, the aircraft heading is 214°T (209°M), this is also the heading shown by the info bar. 209°M is confirmed by the HUD's heading tape when in the catapult. Your programmed TACAN course is 214°M i.e. to the right of your current heading. This is how it looks diagrammatically Edited August 21, 2021 by Ramsay 1 i9 9900K @4.7GHz, 64GB DDR4, RTX4070 12GB, 1+2TB NVMe, 6+4TB HD, 4+1TB SSD, Winwing Orion 2 F-15EX Throttle + F-16EX Stick, TPR Pedals, TIR5, Win 10 Pro x64, 1920X1080 Link to comment Share on other sites More sharing options...
Frederf Posted August 21, 2021 Share Posted August 21, 2021 Since HSI orientation is track-up then HSI orientation should change as track azimuth changes regardless of heading (constant or otherwise). I assume when at zero/small velocity (track azimuth undefined) that system switches over to using heading as a substitute. 1 Link to comment Share on other sites More sharing options...
Topper81 Posted August 22, 2021 Author Share Posted August 22, 2021 Ok I haven't known that it's track up orientated. I guess this should be the case in flight but not on the deck and it switches to be "heading orientated" on the deck because you don't want to know the direction where the carrier is moving to when you are moving on the deck. So the behaviour makes sence. Link to comment Share on other sites More sharing options...
Swift. Posted August 22, 2021 Share Posted August 22, 2021 It's T UP wherever you are, but obviously on the deck it gets funky because you could be tracking North whilst heading south. 476th Discord | 476th Website | Swift Youtube Ryzen 5800x, RTX 4070ti, 64GB, Quest 2 Link to comment Share on other sites More sharing options...
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