felixx75 Posted August 11, 2020 Share Posted August 11, 2020 Why is there a difference between the radar altitude shown in the Radar Altimeter Gauge (120m) and shown in the HUD (108m)? Should it not be the same? Link to comment Share on other sites More sharing options...
Fusedspine33 Posted August 11, 2020 Share Posted August 11, 2020 Why is there a difference between the radar altitude shown in the Radar Altimeter Gauge (120m) and shown in the HUD (108m)? Should it not be the same? Looks like you uploaded thumbnails and not photos, so it's hard to see what you are. Sent from my iPad using Tapatalk Link to comment Share on other sites More sharing options...
felixx75 Posted August 11, 2020 Author Share Posted August 11, 2020 Looks like you uploaded thumbnails and not photos, so it's hard to see what you are. Sent from my iPad using Tapatalk Nope, you can enlarge it, just click on it. But I will reupload it. Link to comment Share on other sites More sharing options...
QuiGon Posted August 11, 2020 Share Posted August 11, 2020 Looks like you uploaded thumbnails and not photos, so it's hard to see what you are. They show up fine for me :huh: In regards to OPs question I don't know why there is such a difference :dunno: Intel i7-12700K @ 8x5GHz+4x3.8GHz + 32 GB DDR5 RAM + Nvidia Geforce RTX 2080 (8 GB VRAM) + M.2 SSD + Windows 10 64Bit DCS Panavia Tornado (IDS) really needs to be a thing! Link to comment Share on other sites More sharing options...
felixx75 Posted August 11, 2020 Author Share Posted August 11, 2020 Does is make a difference if you are over land vs water with them matching up? I watched this older YouTube to see if they matched up over land and they seem to: Edit: Here's one over water I think you may have found a bug. I'll fire up the Ka-50 later and see what I see. It seems to be always the same difference, over land and over water. Link to comment Share on other sites More sharing options...
Flagrum Posted August 11, 2020 Share Posted August 11, 2020 (edited) Which altitude does the F2-view status bar show? Is the difference always the same or does it change depending on the acutal altitude of the helo? Edited August 11, 2020 by Flagrum Link to comment Share on other sites More sharing options...
Taz1004 Posted August 11, 2020 Share Posted August 11, 2020 Which altitude does the F2-view status bar show? Is the difference always the same or does it change depending on the acutal altitude of the helo? F2 always shows Baro altitude I believe. I checked it with Tacview and the HUD indication seems to be the correct one. I always thought the gauge is analog and has some delay or lag than the digital one on the HUD. Better Smoke - Better Trees Caucasus - Better Trees Syria - Better Trees Mariana - Clear Canopy Glass Link to comment Share on other sites More sharing options...
Frederf Posted August 11, 2020 Share Posted August 11, 2020 It's possible that the HUD is showing the Doppler system height while the round gauge shows the radar altimeter height. I'm surprised they are so different though. What are their values compared to true height (true altitude - terrain elevation)? Does it depend on helicopter attitude? Link to comment Share on other sites More sharing options...
QuiGon Posted August 12, 2020 Share Posted August 12, 2020 Another noticeable difference is flying over objects such as buildings. The HUD Radar Altimeter jumps around depending on the objects below the aircraft, whereas the Radar Altimeter Gauge does not. This was a really nice find by the OP. This really sounds like a bug. Intel i7-12700K @ 8x5GHz+4x3.8GHz + 32 GB DDR5 RAM + Nvidia Geforce RTX 2080 (8 GB VRAM) + M.2 SSD + Windows 10 64Bit DCS Panavia Tornado (IDS) really needs to be a thing! Link to comment Share on other sites More sharing options...
Blackjack_UK Posted August 12, 2020 Share Posted August 12, 2020 Sounds like a bug to me as well - I've posted it as such and linked back to here. [sIGPIC][/sIGPIC] Link to comment Share on other sites More sharing options...
Taz1004 Posted August 12, 2020 Share Posted August 12, 2020 Off by 10% definitely sounds like a bug. But how should it work in real life? If you fly over rough terrain, would the needle bounce rapidly exactly as the HUD number fluctuates? And it looks like low altitude warning is based off the analog gauge and not the HUD or ABRIS. Wouldn't this trip the low altitude warning all the time if it fluctuates rapidly? Better Smoke - Better Trees Caucasus - Better Trees Syria - Better Trees Mariana - Clear Canopy Glass Link to comment Share on other sites More sharing options...
Frederf Posted August 12, 2020 Share Posted August 12, 2020 Beslan takeoff Ground elevation 525m F2 ALT 526m RALT =<0m HUD 001p F2 ALT 625m RALT 112m HUD 100p Suspiciously the yellow warning triangle is exactly equal to the needle when at actual 100m height going off when descending to F2 ALT 624m. I think the needle and yellow caret rotation angle in radians is miscalibrated compared to the texture art on the gauge background. I had a hunch since rotational scale is non-linear. Scale is calibrated to 0m and 300m very well. If I fly at 826m (300m height) then 300m mark on A-036 instrument lines up perfectly. It is the middle heights which are not correlating so well. \Mods\aircraft\Ka-50\Cockpit\Scripts\Devices_specs\RadarAltimeter.lua has line raltPointer = {valmin = 0, valmax = max_alt, T1 = 0.75, T2 = 0.316, wmax = 0, bias = {{valmin = 0, valmax = max_alt, bias = 0.1}}} The A-036 "kicks" on and off about ~310m which can be seen by the needle jump. This corresponds to the distance_lim = 310.0 in the LUA. I don't know what the distance_lim_precise = 410.0 refers to. This controls the rotation of the white needle. "T1" and "T2" are calibration coefficients I think which may be enough to calibrate the input value to the needle output rotation correctly if different values are used. Table of gauge background values to rotational angles: m ° 0 0 10 31 20 62 30 93 40 124 50 156 100 209 150 260 200 283 300 315 Compare this to the actual height value to rotational angles: m ° 0 0* 10 31* 20 65* 30 98* 40 132 50 172 100 224 150 269 200 290 300 315 *1m difference in F2 ALT height compared to ground elevation while landed is a significant fraction of the indication. Usually gauge is calibrated to show 0m when helicopter is landed even if object center is 1m above ground elevation. Attached is graph visualizing the difference. In summary I think A-036 needle rotation is not rotated to the correct angular position for various heights. Link to comment Share on other sites More sharing options...
Krez Posted August 15, 2020 Share Posted August 15, 2020 Another noticeable difference is flying over objects such as buildings. The HUD Radar Altimeter jumps around depending on the objects below the aircraft, whereas the Radar Altimeter Gauge does not. This was a really nice find by the OP. Why would that be a bug? Isn't that your actual altitude when over a an object? If you were in a hover, wouldn't you want to know how far you can descend before you collide with an obstruction? That is working as intended. Link to comment Share on other sites More sharing options...
QuiGon Posted August 15, 2020 Share Posted August 15, 2020 Why would that be a bug? Isn't that your actual altitude when over a an object? If you were in a hover, wouldn't you want to know how far you can descend before you collide with an obstruction? That is working as intended. Sure, but the analogue gauge should jump as well. That's the bug he's talking about. ;) Intel i7-12700K @ 8x5GHz+4x3.8GHz + 32 GB DDR5 RAM + Nvidia Geforce RTX 2080 (8 GB VRAM) + M.2 SSD + Windows 10 64Bit DCS Panavia Tornado (IDS) really needs to be a thing! Link to comment Share on other sites More sharing options...
Blackjack_UK Posted August 16, 2020 Share Posted August 16, 2020 Because the panel gauge and HUD should read the same... [sIGPIC][/sIGPIC] Link to comment Share on other sites More sharing options...
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