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.
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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 have always wonder the same
For surw BMS modeling is incorrect.
Would like to know RL pilot input
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I have always wonder the same
For surw BMS modeling is incorrect.
Would like to know RL pilot input
What would make the most sense, IMO, is that it adapts the antenna pattern to take pitch and roll attitude into account. Bars should always be horizontal and as long as the requested elevation is within gimbal limits, the radar scans it.
On ships for example, the radars are stabilized too, otherwise, they would spend half the time pointing directly at the sea and the other at the sky. For a surface-search radar, that is not exactly optimal…
Obviously, a pilot input would be nice
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the radar should be horizon stabilized
I’m no radar specialist but when i read in SOPs or in normal procedures that the antenna needs to be tilted a few degrees up for a RAT (Radar assisted Trail departure)
it seems the antenna stays on the horizon although the aircraft pitches up 10° on the gun cross, hence the need to manually tilt it up to paint the guy in front of you (who is higher). -
I guess another thing that would come into play is how fast the RADAR can actually move. (not a factor with AESA, perhaps?)
At a fixed pitch angle of 30°, I suppose it can still remain stabilized on the horizon, but if you fly level and pull a lot of G to that 30°, can the radar keep up or will there be a delay? If so, how long will that delay be?
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I guess another thing that would come into play is how fast the RADAR can actually move. (not a factor with AESA, perhaps?)
At a fixed pitch angle of 30°, I suppose it can still remain stabilized on the horizon, but if you fly level and pull a lot of G to that 30°, can the radar keep up or will there be a delay? If so, how long will that delay be?
Good point as well. But you can see the bar scan in the radar screen, it scans 60° in 2s, so I think the delay would be not that significant anyway. Obviously, this is assuming the antenna moves as fast in pitch and in yaw.
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imo, the radar gamble can handle a lot of pitch. Look at the AG operations. 45* lofting at targets less than 5nm. Or is that a SPI trick?
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As far as I know, stabilized in pitch +/-60° … Not in roll.
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As far as I know, stabilized in pitch +/-60° … Not in roll.
So as soon as you bank a bit, you lose a lot of coverage…. if it is indeed the case, that could be interesting to implement.
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So as soon as you bank a bit, you lose a lot of coverage….
It depends on your alt, bank angle, where you are looking (distance) and antenna elevation ….
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It depends on your alt, bank angle, where you are looking (distance) and antenna elevation ….
Absolutely ! But still, the forward “rectangle” that you are scanning will be rotated with your bank.
So as soon as you bank a bit much, your coverage is more vertical than horizontal anyway.
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An Inertial Measurement Unit is mounted to the base of the antenna to provide automatic boresight correction capability. There are four coordinate systems used by the radar to allow the best functionality based on the radar mode, providing stability vs the horizon (pitch) and roll within gimbals among others.
BTW, the radar would anyway benefit from a complete update…
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An Inertial Measurement Unit is mounted to the base of the antenna to provide automatic boresight correction capability. There are four coordinate systems used by the radar to allow the best functionality based on the radar mode, providing stability vs the horizon (pitch) and roll within gimbals among others.
BTW, the radar would anyway benefit from a complete update…
Bot how can make such a compenstaion which is impossible?
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As far as I know, stabilized in pitch +/-60° … Not in roll.
Ok this one had be digging through the books as it wasn’t a problem that I ever addressed. It is stabilized in pitch and in roll. You can momentarily lose roll stabilization in FCR due to the high roll rate of the F-16.
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An Inertial Measurement Unit is mounted to the base of the antenna to provide automatic boresight correction capability. There are four coordinate systems used by the radar to allow the best functionality based on the radar mode, providing stability vs the horizon (pitch) and roll within gimbals among others.
This is not correct. The FCR receives Pitch, Roll, and Magnetic heading from either the INS directly or indirectly through the FCC/GAC/MMC for stabilization. Those signals go from the INS/MMC to the PSP in the FCR system. The PSP directs the movement of the antenna for stabilization.
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Bot how can make such a compenstaion which is impossible?
Of course its possible. You adjust the antenna pattern to take into account the pitch and roll, thats all.
Ex :
-AC is banking 25° clockwise-> you rotate the bars 25° counterclockwise so that they remain horizontals.
-AC is pitching 15° up -> you move the antenna elevation 15° down so that you scan the same volume.
Etc.Antenna moves quite fast, so except in limit roll, it can catch up quite fast.
Pitch and roll attitude is given by the INS, probably.
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Of course its possible. You adjust the antenna pattern to take into account the pitch and roll, thats all.
Ex :
-AC is banking 25° clockwise-> you rotate the bars 25° counterclockwise so that they remain horizontals.
-AC is pitching 15° up -> you move the antenna elevation 15° down so that you scan the same volume.
Etc.Antenna moves quite fast, so except in limit roll, it can catch up quite fast.
Pitch and roll attitude is given by the INS, probably.
Correct. The FCR takes this information (pitch, roll, magnetic heading) from the INS and uses it to stabilize in pitch and in roll. Obviously if the pilot goes outside of the physical gimbal limits of the FCR the it will have to do something else. I’m not sure what it does in that situation as the CDCs didn’t cover that situation.
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Bot how can make such a compenstaion which is impossible?
The B-scope is a graphical representation of ranges and vector. Altitude is computed by slant angle and range. Velocity and heading is computed by a historical track file. FCR know its INS attitude.
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This is not correct.
Well, it was pasted as-is…
The FCR receives Pitch, Roll, and Magnetic heading from either the INS directly or indirectly through the FCC/GAC/MMC for stabilization. Those signals go from the INS/MMC to the PSP in the FCR system. The PSP directs the movement of the antenna for stabilization.
The FCR takes this information (pitch, roll, magnetic heading) from the INS and uses it to stabilize in pitch and in roll.
Pitch and roll attitude is given by the INS, probably.
So according to your assumption, if the bird looses INS, = no radar proper operation due to drifts… Or better, if INS = off, and GPS = jammed or EGI lost alignment, then again no radar proper tracking…
The antenna movement vs aircraft reactions is controlled from its dedicated Inertial Measurement Unit. The FCR through MMC and INS provide target data placement in the 3D space and FCR MFD.
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If the GPS fails and the INS drift it porks Bullseye and the HSD bug from other flight member’s d-link. It still does BRA just like the days before GPS. It has happen to me a few times in F4AF MP.