AN/APG-77 vs DRFM jammer

Anything goes, as long as it is about the Lockheed Martin F-22 Raptor
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hcobb

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Unread post25 Dec 2011, 03:48

The F-22 has a lifespan of 30 years or 8000 flight hours, whichever comes first.

Fortunately they haven't been burning down those flight hours lately. :-(
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southernphantom

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Unread post25 Dec 2011, 16:53

hcobb wrote:The F-22 has a lifespan of 30 years or 8000 flight hours, whichever comes first.

Fortunately they haven't been burning down those flight hours lately. :-(


And that's before the possible SLEP c.2030-2040.
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hcobb

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Unread post27 Dec 2011, 21:16

The big loss factor at the moment is those lousy pilots who insist on breathing instead of paying attention to flying the aircraft. (The USAF should like totally sue whatever organization it was who selected and trained those bozos.) So there might not be that many F-22s left to SLEP. :-(

Pity the USAF is against a FB-22 style next-gen bomber, but perhaps a twin-engine cross between the F-22 and F-35s could be built in the late 2020s, depending on how the 6th gen program goes.
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wrightwing

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Unread post29 Dec 2011, 02:25

southernphantom wrote:
The only Raptors over here are at Tyndall, which aren't on alert like the F-15s are. Homestead ARB has the 125th FW Det. 1 on NORAD support alert. IIRC, there aren't any Raptors on alert anywhere.

Where exactly did these Su-35s flying over Florida, fly out of? They would've run out of fuel long before reaching Florida, if they were Venezuelan. They would've likely been engaged by the USN long before any USAF/ANG alert fighters ever got scrambled.
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Code3

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Unread post29 Dec 2011, 04:16

southernphantom wrote:The only Raptors over here are at Tyndall, which aren't on alert like the F-15s are. Homestead ARB has the 125th FW Det. 1 on NORAD support alert. IIRC, there aren't any Raptors on alert anywhere.


Looks like the Raptors out of Elmendorf must be on alert some of the time...

http://www.aviationweek.com/aw/blogs/defense/index.jsp?plckController=Blog&plckScript=blogscript&plckElementId=blogDest&plckBlogPage=BlogViewPost&plckPostId=Blog%3A27ec4a53-dcc8-42d0-bd3a-01329aef79a7Post%3Ad07dbc0a-1db1-426e-ae3f-84e2177c1b18[/url]
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Scorpion1alpha

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Unread post02 Jan 2012, 01:57

Code3 wrote:
southernphantom wrote:The only Raptors over here are at Tyndall, which aren't on alert like the F-15s are. Homestead ARB has the 125th FW Det. 1 on NORAD support alert. IIRC, there aren't any Raptors on alert anywhere.


Looks like the Raptors out of Elmendorf must be on alert some of the time...

http://www.aviationweek.com/aw/blogs/defense/index.jsp?plckController=Blog&plckScript=blogscript&plckElementId=blogDest&plckBlogPage=BlogViewPost&plckPostId=Blog%3A27ec4a53-dcc8-42d0-bd3a-01329aef79a7Post%3Ad07dbc0a-1db1-426e-ae3f-84e2177c1b18[/url]


Some more:

http://www.pacaf.af.mil/news/story.asp?id=123246683

On Thanksgiving Day, 2007, klaxon alarms in then Elmendorf Air Force Base's Combat Alert Center pierced the winter air, prompting pilots to hurriedly suit up and slide down the facility's fire pole, dashing down the ready line to their F-22 Raptor fighters.

Within minutes of the call, the F-22s were airborne en route to intercepting a Russian Air Force TU-95 Bear bomber just southeast of Nunivak Island, mere miles away from the Alaska mainland.


Last month (since 2007), the CAC earned a "mission ready" rating when Air Force inspectors general visited the facility for a North American Aerospace Defense Command Alert Force Evaluation.


Crew chiefs from 90th and 525th aircraft maintenance units were tested for how quickly they could safely launch alert aircraft, as well as how soon they could turn the returning aircraft around for future missions.

Finally, F-22 pilots were evaluated for how quickly, safely and accurately they intercepted the notional incursion aircraft.


The CAC is home to a firehouse atmosphere with sleeping quarters, a weight room and recreational facilities for Airmen who work alert shifts. The F-22s rest in immaculate bays and are constantly checked and rechecked by maintenance personnel to ensure their readiness.

"We're here 24/7/365," Brown said with a grin. "Always ready."


"We're part of history in two aspects: one, we're working in history and two - being the first F-22 alert force - we're making history, all in the same facility."
I'm watching...
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hcobb

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Unread post02 Jan 2012, 02:53

"The F-22s rest in immaculate bays and are constantly checked and rechecked by maintenance personnel to ensure their readiness. "

and

"In July 2009, the Air Force reported that the F-22 requires more than 30 hours of maintenance for every flight hour, with the total cost per flight hour of $44,000.[189] The Office of the Secretary of Defense puts that figure at 34 hours of maintenance per flight hour at a cost of $49,808."

Obviously have something in common.
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wrightwing

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Unread post03 Jan 2012, 17:22

hcobb wrote:"The F-22s rest in immaculate bays and are constantly checked and rechecked by maintenance personnel to ensure their readiness. "

and

"In July 2009, the Air Force reported that the F-22 requires more than 30 hours of maintenance for every flight hour, with the total cost per flight hour of $44,000.[189] The Office of the Secretary of Defense puts that figure at 34 hours of maintenance per flight hour at a cost of $49,808."

Obviously have something in common.


http://www.f-16.net/f-16_forum_viewtopic-t-12877.html

Assertion: F-22 maintenance man-hours per flying hour have increased, recently requiring more than 30 hours of maintenance for every hour airborne.

Facts: The F-22 is required to achieve 12.0 direct maintenance man-hours per flight hour (DMMH/FH) at system maturity, which is defined to be when the F-22 fleet has accumulated 100,000 flight hours. In 2008 the F-22 achieved 18.1 DMMH/FH which then improved to 10.5 DMMH/FH in 2009. It's important to recognize this metric is to be met at system maturity, which is projected to occur in late 2010. So the F-22 is better than the requirement well before maturity.


Assertion: The airplane is proving very expensive to operate with a cost per flying hour far higher than for the warplane it replaces, the F-15.

Facts: USAF data shows that in 2008 the F-22 costs $44K per flying hour and the F-15 costs $30K per flying hour. But it is important to recognize the F-22 flight hour costs include base standup and other one-time costs associated with deploying a new weapon system. The F-15 is mature and does not have these same non-recurring costs. A more valid comparison is variable cost per flying hour, which for the F-22 in 2008 was $19K while for the F-15 was $17K.


It's amazing what you can find, if you don't stop looking, once you've found what you want to find.
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thestealthfighterguy

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Unread post05 Jan 2012, 04:10

wrightwing wrote:
hcobb wrote:"The F-22s rest in immaculate bays and are constantly checked and rechecked by maintenance personnel to ensure their readiness. "

and

"In July 2009, the Air Force reported that the F-22 requires more than 30 hours of maintenance for every flight hour, with the total cost per flight hour of $44,000.[189] The Office of the Secretary of Defense puts that figure at 34 hours of maintenance per flight hour at a cost of $49,808."

Obviously have something in common.


http://www.f-16.net/f-16_forum_viewtopic-t-12877.html

Assertion: F-22 maintenance man-hours per flying hour have increased, recently requiring more than 30 hours of maintenance for every hour airborne.

Facts: The F-22 is required to achieve 12.0 direct maintenance man-hours per flight hour (DMMH/FH) at system maturity, which is defined to be when the F-22 fleet has accumulated 100,000 flight hours. In 2008 the F-22 achieved 18.1 DMMH/FH which then improved to 10.5 DMMH/FH in 2009. It's important to recognize this metric is to be met at system maturity, which is projected to occur in late 2010. So the F-22 is better than the requirement well before maturity.


Assertion: The airplane is proving very expensive to operate with a cost per flying hour far higher than for the warplane it replaces, the F-15.

Facts: USAF data shows that in 2008 the F-22 costs $44K per flying hour and the F-15 costs $30K per flying hour. But it is important to recognize the F-22 flight hour costs include base standup and other one-time costs associated with deploying a new weapon system. The F-15 is mature and does not have these same non-recurring costs. A more valid comparison is variable cost per flying hour, which for the F-22 in 2008 was $19K while for the F-15 was $17K.


It's amazing what you can find, if you don't stop looking, once you've found what you want to find.

Only 2k more. That's what I'm talking about. Thanks for the info.

TSFG
Stealth, so the bad guys don't know your there till they start blowing up. Have a nice day!
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southernphantom

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Unread post05 Jan 2012, 22:55

Well, I stand corrected on the Raptor, and am actually happy to be wrong.

As for the Su-35s, I was at least partially thinking some wonky Cuba scenario, but VZ Flanker-Es would go bingo before they even passed over Cuba. That was just an idly-suggested example of AESA fun, and not intended as a realistic possibility.
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popcorn

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Unread post10 Jan 2012, 12:23

If the variable cost per flying hour for the raptor was $17K in 2008, does anyone know wherr we can find more recent cost figures? Is this type of information classified or would the GAO have access to them?
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icemaverick

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Unread post22 Feb 2012, 18:12

It would be very difficult to jam a good AESA radar. First, a low probability of intercept signal has to be intercepted. It has to be distinguished from the background radiation. After it is detected, processed etc. the signal then has to be sent back to the emitter. The problem is that by then, the frequency has already changed. The Raptor's radar changes frequencies 1000 times PER SECOND! Also, the Raptor has multiple send/receive modules working simultaneously at different frequencies. Finally, an AESA can operate on a very wide range of frequencies unlike most radars which have a narrow range.

So basically the jammer would have to detect multiple simultaneous LPI signals that change frequency 1000 times per second AND over a wide band and send them back. That's a pretty tall order. A good ECM suite would be able to detect that it's being scanned by a good AESA radar, but it wouldn't be able to jam it.
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mityan

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Unread post20 Jun 2013, 13:14

Excuse me guys for bringing to top such an old conversation, but let me make my guess.
icemaverick wrote:It would be very difficult to jam a good AESA radar.

The property of AESA is higher reciever sensivity. Sensivity implies security and this contradicts with jam resistance requirements. So to jam AESA I think is not more difficult than PESA and even easier.
icemaverick wrote:First, a low probability of intercept signal has to be intercepted. It has to be distinguished from the background radiation.

No need to distinguish. DRFM only receives a band of frequencies and outputs them back with diferent time and frequency shifts. Cause this is a newest technology, I think it should not have problems with LPI detection.
icemaverick wrote:After it is detected, processed etc. the signal then has to be sent back to the emitter. The problem is that by then, the frequency has already changed. The Raptor's radar changes frequencies 1000 times PER SECOND!

The problem is that anyway in high PRF mode the radar cannot vary its operating frequency from pulse to pulse but only from one resolution element (azimuth/elevation) to another. So the frequency is constant for (you said) 1 ms. But for detection and shifting response signal parameters only few microseconds required (for example 20) so you lose 98% of your true returns in false ones.
icemaverick wrote:Also, the Raptor has multiple send/receive modules working simultaneously at different frequencies. Finally, an AESA can operate on a very wide range of frequencies unlike most radars which have a narrow range.

There are two kinds of multibeam ESA - with dependent beams and independent.
In all ESA (except the future digitally scanned concept) there is a single DAC analog output and ADC analog input. Output signal is split up to a numerous of antenna elements then amplified and phaseshifted in AESA, or amplified then split up and phaseshifted in PESA. Input signal - vise-versa.
Assuming one value of phase shift the multiple frequency signal will produce multiple beams with different steering angles, cause phaseshift is frequency-dependent parameter. These are pedendent beams.
For independent beams one should have several phase shifters in each transmit/receive channel and that is why the number of beams/frequencies is very limited, but in this case all beams may be steered to one angle (to one point - the target).
So the number of beams is maybe 4 or 5, I think, and their frequencies are not very far from each other, cause the transmitter/receiver is one. There may be very good DAC for example 100 MHz sample rate (remember the times APG-77 being developed) so this is a beam spacing but not the whole 4 GHz band.
So there are no multiple beams - up to 5 I suggest.
Also the antenna elements may be assigned to different frequencies independently - but this means loss of antenna gain (because of aperture reduction) and seems sensless.
icemaverick wrote:So basically the jammer would have to detect multiple simultaneous LPI signals that change frequency 1000 times per second AND over a wide band and send them back. That's a pretty tall order. A good ECM suite would be able to detect that it's being scanned by a good AESA radar, but it wouldn't be able to jam it.

Although there are some delusions on account of antenna design and operation in your post, the LPI AESA radar detection and jamming is still a great challenge, but I dont think it is impossible for such an advanced technique as DRFM.
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wrightwing

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Unread post22 Jun 2013, 08:51

Lot's of fallacies, in that guess.
-Sensitity, has nothing to do with susceptibility to jamming
-PESA radars don't have nearly the frequency agility of AESA arrays
-You've made assumptions about how DRFM jammers work. It's the RWR that must first determine if a signal is background noise, or not. Once it is determined to be a hostile radar, it has to analyze the waveforms, prior to the DRFM jammer being able to mimic the signals.
-LPI doesn't just involve the characteristics of the signal itself, but in techniques (i.e. in addition to frequency and waveform agility ,narrow beams, variable power output, duration of scan, etc..) In other words, the F-22 isn't flying around with its radar constantly scanning.
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mityan

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Unread post24 Jun 2013, 13:51

wrightwing wrote:Lot's of fallacies, in that guess.
-Sensitity, has nothing to do with susceptibility to jamming
-PESA radars don't have nearly the frequency agility of AESA arrays
-You've made assumptions about how DRFM jammers work. It's the RWR that must first determine if a signal is background noise, or not. Once it is determined to be a hostile radar, it has to analyze the waveforms, prior to the DRFM jammer being able to mimic the signals.
-LPI doesn't just involve the characteristics of the signal itself, but in techniques (i.e. in addition to frequency and waveform agility ,narrow beams, variable power output, duration of scan, etc..) In other words, the F-22 isn't flying around with its radar constantly scanning.

Why? Higher sensivity allows to reduce power so the J/S (jam to signal) ratio increases.

PESA - sure - have no the comparable frequency agility with that one of AESA. I only wanted to stress that this 'multiple' number of beams is very limited. There is a very complicated task to design a TRM with only single phaseshifting channel for X-band (i.e. small size) with the proper heat sink (for example). All the more is with several channels.

About how DFM works there is a good book in web - Introduction to Electronic Defense Systems by Filippo Neri. It can be found for free download.
I agree that F-22 is not tracking the target with continuous scan but it also doesnt need a great time to identify and output a response for DRFM, I think.
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