Pakistan F-16 Discussions 2

[blain2]

This was posted on Pakdef forum by Mr. H Khan on 12-09-2009....


"PAF used to operate two DA-20 but I think March of 2008 added third DA-20 in the sqd. The first two Blinders went through are a very extensive upgrade program and each aircraft spend close to 16 months in France for structural overhaul and upgrade. They have become a very potent platform. This upgrade was performed starting late 2004 and ending middle of 2007. The VIP is still in service as a VIP but soon to be sold off as scrape. If someone can add the third name of the aircraft, first two are Haider & Iqbal.....anyone for the third name? "

Regards..

The third one is "Lodhi".

 

[fatman17]

The third one is "Lodhi".

btw our very own x_man flew one of the DA-20's to paris for an overhaul - which overhaul it was, maybe he can comment on!!!

 

[cloyce]

I have a curiosity about F-16 equipped with Sabr AESA radar.

Aircrafts like F-22 has dedicated cooling gates for cooling AESA radar heat. Like this :

http://img204.imageshack.us/img204/8162/f22aesa.jpg


But according to Northrop Grumman, their Sabr AESA will be able to refit all F-16s with "no structural, power or cooling modifications".

How is that possible? Will this thing affect the radar performace compared to "native" AESA fighters like F-22?

Thanks.

 

[Patriot]

Sabr AESA is not as advanced as APG-77 currently used in F22.Sabr Aesa is compact but advanced radar.It is not as good as APG-77 but still better then the current radar on block 52.OTOH, F16 Block 60 has the same AESA Radar which is used on Hornet.

 

[Manticore]

 

[cloyce]

Sabr AESA is not as advanced as APG-77 currently used in F22.Sabr Aesa is compact but advanced radar.It is not as good as APG-77 but still better then the current radar on block 52.OTOH, F16 Block 60 has the same AESA Radar which is used on Hornet.

You are very kind for answer me.

Now, just let me ask you one more thing.

So, is the lower performance related to the lack of a dedicated cooling gate? If it's true. Why I can't spot anyone on a F-35 body?

Thanks in advance.

 

[SQ8]

Found it...deleted..

Apparently the newer falcons were refueled by a Kc-10 on their delivery flight here...

 

[Dazzler]

Sabr AESA is not as advanced as APG-77 currently used in F22.Sabr Aesa is compact but advanced radar.It is not as good as APG-77 but still better then the current radar on block 52.OTOH, F16 Block 60 has the same AESA Radar which is used on Hornet.

SABR is small, compact and designed as an upgrade option and does not need additional cooling hence it can be readily accommodated in existing f-16 nose cone. Radar on blk 60 is APG-80 and on F-18 SH is APG-79, both are different in size and capability where the latter triumphs the former in range, power and additional functions.

Also, one is manufactured by Northrop Grumman (apg-80) and other is by Raytheon (APG-79)

 

[gambit]

So, is the lower performance related to the lack of a dedicated cooling gate? If it's true. Why I can't spot anyone on a F-35 body?

No. In radar detection, there are three major items that affect overall performance of a system:

- Antenna size
- Beam width
- Resolution cell

The larger the antenna, the narrower the beam width, and this affect resolution cell...

Definition: radar resolution cell

radar resolution cell: The volume of space that is occupied by a radar pulse and that is determined by the pulse duration and the horizontal and vertical beamwidths of the transmitting radar. Note: The radar cannot distinguish between two separate objects that lie within the same resolution cell.

Cooling can be achieved through other means than vents or ram air ducting.

Now...If the radar is designed for volume search and this is the domain of AWACS, then resolution cell becomes secondary importance. Basically, at several hundreds km out, it really does not matter if you can distinguish individual targets or not. You just need to cover as much of the sky and as fast as possible. So a large antenna in combination with the mhz bands will produce the optimum power for distance and beam width for coverage over any period of time.

 

[blain2]

Good info Gambit!

 

[MastanKhan]

Cooling can be achieved through other means than vents or ram air ducting.

Now...If the radar is designed for volume search and this is the domain of AWACS, then resolution cell becomes secondary importance. Basically, at several hundreds km out, it really does not matter if you can distinguish individual targets or not. You just need to cover as much of the sky and as fast as possible. So a large antenna in combination with the mhz bands will produce the optimum power for distance and beam width for coverage over any period of time.

Hi,

About a year ago I read that Aesa can detect the number of blades on the jet engine----determing what kind of engine it is---thus what kind of aircraft and how many---even if they are flying real close---I lost that article somewhere---. What is your input on that! Thankyou.

 

[MastanKhan]

www.es.northropgrumman.com/solutions/aesaradar/index.html


Hi,

Some great info on radar systems.

 

[DESERT FIGHTER]

Sorry for being off topic but cant we absorb some techs from our F-16s n use them on JFTs?

 

[MastanKhan]

Active Electronically Steered Arrays - A Maturing Technology

 

[gambit]

Hi,

About a year ago I read that Aesa can detect the number of blades on the jet engine----determing what kind of engine it is---thus what kind of aircraft and how many---even if they are flying real close---I lost that article somewhere---. What is your input on that! Thankyou.

While the superiority of even the basic ESA system is undisputed and that the ability of an AESA system to create a beam width that -- in theory -- could do what is claimed, I would reserve judgment on that claim. The issue here is complex...

- The amount of reflective surfaces that are available for any pulse in any time period.
- Beam dispersion or 'widening'.
- Moving surfaces.

A series of pulses is called appropriately enough a 'pulse train'. A jet engine will have several stages of moving blades. A pulse train will exhibit different behaviors on a SINGLE blade because the blade itself is not an ideal geometric figure like a sphere, which exhibit predictable reflective behavior regardless of approach angle, but that the blade will have edges and curves, which will induce different reflective signal behavior. Beam widening because of increasing distance lead us back to the resolution cell property which could make a pulse train to believe two or more blades as one.

Finally there is interference...

Simulcasting

You can think of the two radio signals as waves, with peaks and troughs as they travel from the transmitter to the receiver. If the content of the two signals is the same and the signals arrive at the receiver at exactly the same time, the peaks and troughs will match each other and the two signals will reinforce each other. In this condition the signals are described as in-phase and result in constructive interference. Most receivers perform very well with this positive type of interference.

However, if the content of the two signals is the same but the signals do not arrive at the receiver at the exact same moment, the peaks and troughs won't match up. This condition is known as out of phase and results in destructive interference.

Both types will occur at any point in time in any pulse train precisely because of the moving blades -- in multiple stages at that. And keep in mind that the aircraft is moving as well.

So while under ideal conditions, aka laboratory, we can take static measurements of a jet engine and compare it against known signatures, similar to sonar signatures, and make a reasonably accurate declaration that we are looking at the radar signature of so-and-so engine and therefore at a so-and-so fighter, applications under far less than ideal conditions may not make the attempt technically and financially worthwhile.