Nomad1-1 Posted July 2, 2024 Posted July 2, 2024 Hello everyone, I've had a problem with my fa 18 for several days now. After about 20 minutes, my velocity vector goes out of order and so does the HSI. It can go up to 20 degrees of error. I also have my waypoints in the wrong place on my helmet sight. The mission is in 1989. I do the alignment and wait until it says 0.5-OK, then I put it on IFA. If I land, it returns to center, but as soon as I'm back in the air, it's out of alignment again. Am I doing something wrong, or is it a bug?
Foka Posted July 2, 2024 Posted July 2, 2024 If the mission is in 1989 there is no GPS available, so you should set the INS knob to Nav, not IFA. That won't fix that anyway, because Hornet has standing for years bug in INS that will mess up CCIP reticle if there is no GPS available.
Nomad1-1 Posted July 2, 2024 Author Posted July 2, 2024 (edited) First of all, thank you very much! But what date should I set the mission to get the GPS? Edited July 2, 2024 by Nomad1-1
Solution Shimmergloom667 Posted July 2, 2024 Solution Posted July 2, 2024 4 minutes ago, Nomad1-1 said: First of all, thank you very much! But what date should I set the mission to get the GPS? Anything later than 19940328 i7 - 9700K | 32 GB DDR4 3200 | RTX 2080 | VKB Gunfighter Mk II /w MCG Pro | Virpil T-50CM2 Throttle | TrackIR 5 | VKB Mk. IV AJS-37 | A/V-8B | A-10C | F-14A/B | F-16C | F-18C | F-86F | FC3 | JF-17 | Ka-50 | L-39 | Mi-8 | MiG-15bis | MiG-19 | MiG-21bis | M2000-C | P-51D | Spitfire LF Mk. IX | UH-1H
PawlaczGMD Posted July 5, 2024 Posted July 5, 2024 (edited) On 7/2/2024 at 8:00 AM, Foka said: If the mission is in 1989 there is no GPS available, so you should set the INS knob to Nav, not IFA. That won't fix that anyway, because Hornet has standing for years bug in INS that will mess up CCIP reticle if there is no GPS available. Could you give more information on this? I've observed quite poor accuracy with CCIP/CCRP drops. I am always in IFA with GPS on, and have tried switching POS/AINS to GPS on the HSI, and it might have helped a bit? Does CCIP/CCRP rely on knowing the jet's precise position? It seems like all it should need is relative data - slew angles and range/altitude provided by radar or TGP. is it a bug that self position data even affects such modes? Edited July 5, 2024 by PawlaczGMD
Foka Posted July 5, 2024 Posted July 5, 2024 7 hours ago, PawlaczGMD said: Could you give more information on this? I've observed quite poor accuracy with CCIP/CCRP drops. I am always in IFA with GPS on, and have tried switching POS/AINS to GPS on the HSI, and it might have helped a bit? In my experience CCIP is very accurate.
AndyJWest Posted July 5, 2024 Posted July 5, 2024 7 hours ago, PawlaczGMD said: Could you give more information on this? I've observed quite poor accuracy with CCIP/CCRP drops. I am always in IFA with GPS on, and have tried switching POS/AINS to GPS on the HSI, and it might have helped a bit? Does CCIP/CCRP rely on knowing the jet's precise position? It seems like all it should need is relative data - slew angles and range/altitude provided by radar or TGP. is it a bug that self position data even affects such modes? You need more than that to correct for wind.
PawlaczGMD Posted July 5, 2024 Posted July 5, 2024 2 hours ago, Foka said: In my experience CCIP is very accurate. Not with Cluster munitions, the current fuzing bug aside. 2 hours ago, AndyJWest said: You need more than that to correct for wind. OK, this might be it. So wind is corrected by GPS signal, rather than some airflow sensor? How does the Tomcat correct for wind?
Foka Posted July 5, 2024 Posted July 5, 2024 Also with cluster, you just have to know, that aircraft computer calculates canister drop, and does not take into account wind influence on bomblets on parachutes. But as far as I know that's how it should work. Anyway CBUs in Hornet are useless.
Phantom711 Posted July 5, 2024 Posted July 5, 2024 (edited) vor 1 Stunde schrieb PawlaczGMD: So wind is corrected by GPS signal, rather than some airflow sensor? No…this is not how it works. When you are on the ground, wind is an airmass that is flowing over the ground. So that airmass is moving in relation to the ground in a certain direction and speed. As an aircraft in the air, you are simply within that airmass. The air is not „blowing“ against the surface of the aircraft really, the aircraft is being moved by the air, because it is within it. So a sensor would be useless. The aircraft systems calculate wind, by comparing the aircraft heading vs its resulting track. This works with GPS but also reasonably well with just INS (just less accurate over time). Edited July 5, 2024 by Phantom711 vCVW-17 is looking for Hornet and Tomcat pilots and RIOs. Join the vCVW-17 Discord.
PawlaczGMD Posted July 5, 2024 Posted July 5, 2024 45 minutes ago, Phantom711 said: No…this is not how it works. When you are on the ground, wind is an airmass that is flowing over the ground. So that airmass is moving in relation to the ground in a certain direction and speed. As an aircraft in the air, you are simply within that airmass. The air is not „blowing“ against the surface of the aircraft really, the aircraft is being moved by the air, because it is within it. So a sensor would be useless. The aircraft systems calculate wind, by comparing the aircraft heading vs its resulting track. This works with GPS but also reasonably well with just INS (just less accurate over time). Shouldn't ground radar be able to do this without relying in INS position that gets less and less accurate?
Phantom711 Posted July 5, 2024 Posted July 5, 2024 If the drift of your INS is a concern, then you must use certain methods to update the INS position. What you are suggesting sounds somewhat technically feasable, but I don‘t know if it is done like that on any aircraft. Never heard of it. Usually INS updates are done by overflying a known point or identifying one on the radar. vCVW-17 is looking for Hornet and Tomcat pilots and RIOs. Join the vCVW-17 Discord.
PawlaczGMD Posted July 5, 2024 Posted July 5, 2024 10 minutes ago, Phantom711 said: If the drift of your INS is a concern, then you must use certain methods to update the INS position. What you are suggesting sounds somewhat technically feasable, but I don‘t know if it is done like that on any aircraft. Never heard of it. Usually INS updates are done by overflying a known point or identifying one on the radar. I'm just interested in learning how it works on the Hornet and less so other jets. That is because I observe not great drop accuracy, especially CCRP, and I was interested in how to fix or otherwise correct it. I've seen someone say that changing you position source from AINS to GPS improves it, but I wasn't able to fully verify it. I think the F-14 has better CCRP accuracy than the Hornet, which sounds concerning, as the Tomcat has INS only as far as I know. For another comparison, the KA-50 can have some crazy INS drift, like dozens of meters easily, but retains good CCIP/CCRP accuracy. And yes, it can be updated by overflying a fix point. I don't know of such function in the Hornet.
Recommended Posts