Effect of pitch angle on radar detection altitude
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Long time ago I wanted to ask I just always forgot until I saw in EF2000 (DID, 1995). In Falcon why is not modeled the effect of pitch angle on the elevation values of radar detection? Of course I guess that until a certain angle the system can compensate the effect but for ex if you are in a 60 deg climb or dive is hard to keep the same position if eleavation was the min… or max.
I am not sure if i understand correct. Is this (pic) your question?
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It should be pretty obvious that if you have lost INS and GPS so you only have good weather (IF you even have that) and TACAN to get home your primary concern is getting your bird back home on the ground. The FCR system losing it’s stabilization feature thanks to that is a problem but it is not your PRIMARY problem.
There is a big difference in the question in a situation given “what should the pilot do” and “what behavior will the system exhibit.” If he asks is FCR behavior if X fails it has nothing to do with practical advice. He wants to know how the mechanical system behaves.
I’m curious if radar train limits are 120/120 then it’s a square solid angle. If you go +60 pitch zero bank then the bottom of the search solid angle is parallel to horizon 120 degrees wide. This is easily understood.
But if bank is involved then radar can theoretically see more than 60 degrees off the nose if it’s a combination of lateral and vertical. I wonder if at +80 pitch, 45 bank if the radar will scan the horizon limited in azimuth. Pythagoras says the corner of the search volume should be ~84 deg off the nose.
Is the FCR smart enough to attempt to scan the desired horizontal slice of air if only the corner of the scan volume can reach it? I assume the scan pattern is horizon-seeking (traverse of the antenna is a mix of tilt and pitch if there is non-zero bank). In the case of bank the scanable space becomes rhombus shaped instead of a rectangle.
One more question if you exceed the limits of traverse will the radar scan and detect in the closest scanable slice? Or will it not attempt to acquire contacts outside the expected volume?
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@A.S:
I am not sure if i understand correct. Is this (pic) your question?
Yeah A.S. that is roughly what he is getting at. The question is what happens when you go beyond the physical gimbals of the FCR and it cannot scan the same space you selected. Good question as my CDCs don’t even cover the scenario.
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Well i know the answer (horizontally and vertically), in other words i know where my radar-gimble and -gate is at all times, but ain´t that very simple to test ingame for those who want to find out for themself? I mean just put up a high-aspect engagement online with a mate and at good distance and give it a shot.
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There is a big difference in the question in a situation given “what should the pilot do” and “what behavior will the system exhibit.” If he asks is FCR behavior if X fails it has nothing to do with practical advice. He wants to know how the mechanical system behaves.
Which I had explained and he had verified while explaining this hypothetical situation. He didn’t ask if that is what it would do, he made the statement based on my “assumption” then proceeded to incorrectly state how the system works again.
However just in case it wasn’t clearly received I will re-state how it works. The FCR system gets pitch and roll from the INS system. The PSP in the FCR is what commands the antenna to move about and that is how it is pitch and roll stabilized. The antenna doesn’t have it’s own INS and it doesn’t correct it’s position by itself. That is all commanded via the PSP.
So his hypothetical is correct in that if you lose your INS/GPS then you also lose FCR stabilization as it won’t have INS data to work from.
I’m curious if radar train limits are 120/120 then it’s a square solid angle. If you go +60 pitch zero bank then the bottom of the search solid angle is parallel to horizon 120 degrees wide. This is easily understood.
The antenna can go +/- 60 degrees in both axis so yes 120/120 is correct. So if you went 60 degrees nose high no bank the lowest the scan could go would be at the horizon due to gimbal limits. 70 degrees high no bank, 10 degrees above the horizon, so on and so forth.
But if bank is involved then radar can theoretically see more than 60 degrees off the nose if it’s a combination of lateral and vertical. I wonder if at +80 pitch, 45 bank if the radar will scan the horizon limited in azimuth. Pythagoras says the corner of the search volume should be ~84 deg off the nose.
I’m not a math wizard so I couldn’t tell you that.
Is the FCR smart enough to attempt to scan the desired horizontal slice of air if only the corner of the scan volume can reach it? I assume the scan pattern is horizon-seeking (traverse of the antenna is a mix of tilt and pitch if there is non-zero bank). In the case of bank the scanable space becomes rhombus shaped instead of a rectangle.
One more question if you exceed the limits of traverse will the radar scan and detect in the closest scanable slice? Or will it not attempt to acquire contacts outside the expected volume?
The CDCs don’t even mention what happens in simple circumstances of say 70 degrees pitch no bank. Perhaps a -34 or a -1 explains what it does but I would have to dig farther for answers to that.
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… When you say INS/GPS … Lets by clear, while FRC (radar) can get a/c’s attitude from the INS, it can’t get it from the GPS.
GPS provide only a position, true course, ground speed, altitude relative to the earth mathematic geoid … But ever never can provide a/c’s attitude. -
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@A.S:
I am not sure if i understand correct. Is this (pic) your question?
Yes, mostly this is besides the roll and turn issues.
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Good question.
What about it…? You can do small or large barrel roll. The relative position change of calculated point can be very big which means force the missile high G turns. Should I show it on ACMI?
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Are you honestly trying to state the functions of the FCR system based on what the radome says?
The “radome” = the “@#$%&”… Cannot make it more clear here.
as my CDCs don’t even cover the scenario.
The CDCs don’t even mention what happens in simple circumstances
Lol, do you know why? Because these are covered in the above answer…
It should be pretty obvious that if you have lost INS and GPS so you only have good weather (IF you even have that) and TACAN to get home your primary concern is getting your bird back home on the ground.
The FCR system losing it’s stabilization feature thanks to that is a problem but it is not your PRIMARY problem.
This is the 2nd time you answer different things than what was asked. We don’t care if a situation is difficult, or if the pilot has other_concerns_to_think_that_time, the q and required answer is about the FCR operation at that time so to might code it properly.
The FCR system gets pitch and roll from the INS system.
if you lose your INS/GPS then you also lose FCR stabilization as it won’t have INS data to work from.
My attached printscreen, part of a video to demonstrate exactly this situation, plus many more juices, shows a bird with EGI problem, INS not working/aligning, no GPS signal, but radar lock to a target. So, a simple translation of the pic can give many answers…
Although I do completely respect a profession on a subject, it seems that lack of additional and specific documentation is generating more haos that it tries to solve. I do not intent to continue arguing about stuff, not fighting against you @Stubbies, if devs need to proper model that thing hiding inside the radome I guess they know now what 2 do to benefit coders.
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… When you say INS/GPS … Lets by clear, while FRC (radar) can get a/c’s attitude from the INS, it can’t get it from the GPS.
GPS provide only a position, true course, ground speed, altitude relative to the earth mathematic geoid … But ever never can provide a/c’s attitude.Correct that is more for inclusion of EGI based F-16s where the INS and GPS aren’t separate LRUs. Either way yes it gets the data from the INS.
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The “radome” = the “@#$%&”… Cannot make it more clear here.
The radome isn’t part of the FCR system so frankly it is neither here nor there what a sticker attached to the radome says.
Lol, do you know why? Because these are covered in the above answer…
Sorry dude your answer is wrong. What you linked out of context was specifically what the FCR does when you go beyond gimbals for the FCR scan. It matters not HOW it gets that information for that scenario as you didn’t answer what it does beyond gimbals either.
This is the 2nd time you answer different things than what was asked. We don’t care if a situation is difficult, or if the pilot has other_concerns_to_think_that_time, the q and required answer is about the FCR operation at that time so to might code it properly.
Quite simply no INS = no FCR stabilization.
My attached printscreen, part of a video to demonstrate exactly this situation, plus many more juices, shows a bird with EGI problem, INS not working/aligning, no GPS signal, but radar lock to a target. So, a simple translation of the pic can give many answers…
That doesn’t prove anything dude. The FCR loses stabilization with no INS. It doesn’t STOP working all together. I’d imagine you will break lock during maneuvers but you showed a screen shot. That pilot could have locked on and just pulled the screen shot as it was. You would have to show a video of that sequence to show anything.
Although I do completely respect a profession on a subject, it seems that lack of additional and specific documentation is generating more haos that it tries to solve. I do not intent to continue arguing about stuff, not fighting against you @Stubbies, if devs need to proper model that thing hiding inside the radome I guess they know now what 2 do to benefit coders.
Absolutely amazing that you would take a sticker as gospel but technical data from someone who worked on the aircraft is not even worth consideration. /boggle
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Could be I’m mistaken (if so, disregard and accept my apologies), but I seem to recall Raptor once stated he made his avatar himself. Just saying…
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Could be I’m mistaken (if so, disregard and accept my apologies), but I seem to recall Raptor once stated he made his avatar himself. Just saying…
No m8, not mine, it is real shot from a friend MLU driver via Litening, although I have one same from us using Lantirn.
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What about it…? You can do small or large barrel roll. The relative position change of calculated point can be very big which means force the missile high G turns. Should I show it on ACMI?
Sure it works pefect in the simulator … And we know it because has been tested 10000 times.
What about IRL(?) … I do not know, and all my fighter pilot friends neither. The only thing they realy knows: do not let the SAM fire at you, … and if it has, some other “tips” to try to evade it (which we all knows also because works also in BMS …) but no face in barrel roll in the list.
Edit … Maybe you were talking about large low energy barrel roll when running away(?) … I understood face in barrel roll which is not the same of course
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High aspect missile evasion by barrel roll … not smart i think. Works in game? I don´t know, because i don´t fly like that.
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Yeah just as DJ and AS are pointing out the two ways I could think that this would be testing the missile for a defeat but I just don’t see it happening are in G loading and energy. Modern missile systems can pull massive Gs so I highly doubt that would do it IRL. Possible that in the sim it gets it done ala the adder dodge? Maybe but that would be taking advantage of coding.
Energy defeat even a slow barrel roll is not going to cause the missile to adjust that much. Far away missile wouldn’t be adjust much and near ones that is trying to work Gs more than energy. I’d say the only SAM missile that this could even remotely work on would be a SA-5.