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Radar questions at 40 miles.


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Hi guys,

 

just a quick radar question here. I am alright with using the radar at 10 and 20 miles ... no problem moving the antenna up/down and acquire target. But for the love of god, I cannot detect anything at 40 miles.

 

I tried everything ... going higher than my target and scan lower ... going lower and scan higher ... being at the same altitude and scan up and down. Can't detect anything, and I am talking about huge plane here (like the Il-76).

 

Are you guys able to get contact? Any hints?

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Hi guys,

 

just a quick radar question here. I am alright with using the radar at 10 and 20 miles ... no problem moving the antenna up/down and acquire target. But for the love of god, I cannot detect anything at 40 miles.

 

I tried everything ... going higher than my target and scan lower ... going lower and scan higher ... being at the same altitude and scan up and down. Can't detect anything, and I am talking about huge plane here (like the Il-76).

 

Are you guys able to get contact? Any hints?

 

I think you are expecting to much from the radar.

 

I did some rough calculations a while ago :-

 

Typical frontal areas

2 m^2 T-38/F-5 ?

3 m*2 MiG-21

5 m^2 F-16 fighter

10 m^2 F-15/Su-27 fighter

100 m^2 bomber

 

RCS (dB) of the target

X m^2 = log(X) x 10 dB

 

EDIT: Formula is on page 139

http://calhoun.nps.edu/bitstream/handle/10945/37502/Fuhs_Radar_Cross_Section_1982.pdf

 

Known data (Flat plate Antenna)

===============================

T-38

2 m^2 = 3 dB

Detection range = 10.5 nm @ 20,000 ft

 

Estimated detection ranges @ 20,000 ft

======================================

 

MiG-21

3 m^2 = 5 dB

Detection range = (5dB/3dB)^(1/4) x 10.5 nm = 1.14 x 10.5 nm = 12 nm (+14%)

 

F-16

5 m^2 = 7 dB

Detection range = (7dB/3dB)^(1/4) x 10.5 nm = 1.24 x 10.5 nm = 13 nm (+24%)

 

F-15/Su-27

10 m^2 = 10 dB

Detection range = (10dB/3dB)^(1/4) x 10.5 nm = 1.35 x 10.5 = 14 nm (+35%)

 

Bomber

100 m^2 = 20 dB

Detection range = (20dB/3dB)^(1/4) x 10.5 nm = 1.61 x 10.5 = 17 nm (+61%)

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I think you are expecting to much from the radar.

 

I did some rough calculations a while ago :-

 

Hi Ramsay,

 

I know you know your stuff, got few replies from you in other threads. In that case, would you say that even if the F-5 can scan at 40 miles, it would probably never pick up any contacts unless its a 747?

 

... or ...

 

I need to let it scan for waaayyyy longer before giving up and the reason why I am not picking anything is because I am not giving enough time for the radar to scan (I usually try a setting, then stop after 15-20 seconds if I did not pick up anything.

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I know you know your stuff, got few replies from you in other threads.

I'm much less certain on this level of stuff.

In that case, would you say that even if the F-5 can scan at 40 miles, it would probably never pick up any contacts unless its a 747?

That is my understanding and why the radar is upgraded to an APG-66 or equivalent for BVR (double the range).

 

AFAIK with the default AN/APQ-159 radar the F-5E was expected (circa 1976) to be guided to the target by GCI, AWACS, etc.


Edited by Ramsay

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I'm much less certain on this level of stuff.

 

That is my understanding and why the radar is upgraded to an APG-66 or equivalent for BVR (double the range).

 

AFAIK with the default AN/APQ-159 radar the F-5E was expected (circa 1976) to be guided to the target by GCI, AWACS, etc.

 

Ok it's probably not a bug then. I will still play around with it, but as long as I can pickup something at 20 miles I will be alright.

 

If anyone else are able to pick something at 40 please let me know alright!

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While I own this module, I’ve spent next to no time in it. So I’m not familiar with the particulars of its radar. However, in general terms a radar can see approaching aircraft at greater distances than receding aircraft.

 

Also in general terms, high pulse repetition frequency (HPRF) will pick up an approaching aircraft at a greater distance than any other setting. In the case of a receding aircraft, you would use a medium PRF setting. So assuming you can select the PRF mode, your radar will “see” an approaching aircraft (front aspect) at its greatest distance in HPRF.


Edited by Ironhand

YouTube Channel: https://www.youtube.com/channel/UCU1...CR6IZ7crfdZxDg

 

_____

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While I own this module, I’ve spent next to no time in it. So I’m not familiar with the particulars of its radar. However, in general terms a radar can see approaching aircraft at greater distances than receding aircraft.

 

Also in general terms, high pulse repetition frequency (HPRF) will pick up an approaching aircraft at a greater distance than any other setting. In the case of a receding aircraft, you would use a medium PRF setting. So assuming you can select the PRF mode, your radar will “see” an approaching aircraft (front aspect) at its greatest distance in HPRF.

That of course can only apply to Pulse Doppler Radars, though.

 

 

In general: don't fret. The MiG-21 can't see you farther out than about 30km/16nm or so either, plus it can hardly see at all near the ground.

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That of course can only apply to Pulse Doppler Radars, though.

 

Hmmm..I thought it’s radar was pulse doppler. Hopefully I’ll have some time Thursday to explore its cockpit a bit more.

YouTube Channel: https://www.youtube.com/channel/UCU1...CR6IZ7crfdZxDg

 

_____

Win 10 Pro x64, ASUS Z97 Pro MoBo, Intel i7-4790K, EVGA GTX 970 4GB, HyperX Savage 32GB, Samsung 850 EVO 250 GB SSD, 2x Seagate Hybrid Drive 2TB Raid 0.

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Hi guys,

 

just a quick radar question here. I am alright with using the radar at 10 and 20 miles ... no problem moving the antenna up/down and acquire target. But for the love of god, I cannot detect anything at 40 miles...and I am talking about huge plane here (like the Il-76).

 

Are you guys able to get contact?

 

Spent some time with the F-5's radar this morning. My max range for an Il-76 was around 38 nm. His two escorts didn't get picked up until later. And around 19 nm for an Su-27 and 18 for a MiG-29. These targets were nose on.

 

 

 

 

BUT...The target's aspect does matter. You'll get the greatest range with a target that's nose on. That same Il-76 (still front aspect) but crossing my flight path at roughly a 45° angle didn't get picked up until 32 nm.

YouTube Channel: https://www.youtube.com/channel/UCU1...CR6IZ7crfdZxDg

 

_____

Win 10 Pro x64, ASUS Z97 Pro MoBo, Intel i7-4790K, EVGA GTX 970 4GB, HyperX Savage 32GB, Samsung 850 EVO 250 GB SSD, 2x Seagate Hybrid Drive 2TB Raid 0.

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Funny thing, you should probably get greater range with a medium aspect target. Hoping the new radar model with the hornet will take some of this into account.

[sIGPIC][/sIGPIC]

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Funny thing, you should probably get greater range with a medium aspect target. Hoping the new radar model with the hornet will take some of this into account.

Perhaps. Maybe those 4 turbofans pointing their mouths right at you give it a higher rcs than when they're not. DK.

YouTube Channel: https://www.youtube.com/channel/UCU1...CR6IZ7crfdZxDg

 

_____

Win 10 Pro x64, ASUS Z97 Pro MoBo, Intel i7-4790K, EVGA GTX 970 4GB, HyperX Savage 32GB, Samsung 850 EVO 250 GB SSD, 2x Seagate Hybrid Drive 2TB Raid 0.

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Spent some time with the F-5's radar this morning. My max range for an Il-76 was around 38 nm. His two escorts didn't get picked up until later. And around 19 nm for an Su-27 and 18 for a MiG-29. These targets were nose on.

 

 

 

 

BUT...The target's aspect does matter. You'll get the greatest range with a target that's nose on. That same Il-76 (still front aspect) but crossing my flight path at roughly a 45° angle didn't get picked up until 32 nm.

 

Very good info Ironhand! I will certainly keep that in mind. Thanks!

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