F-15X as an interceptor

Military aircraft - Post cold war aircraft, including for example B-2, Gripen, F-18E/F Super Hornet, Rafale, and Typhoon.
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marsavian

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Unread post04 Apr 2019, 00:54

sprstdlyscottsmn wrote:
marsavian wrote:BAE who are building EPAWSS also built the F-35 AN/ASQ-239 which detected and jammed the F-22 APG-77. If it can repeat the same trick against the Chinese/Russian AESAs then the odds get much shorter.

Remember that jamming effectiveness is related to the size of the RCS being hidden. For now, I do not assume anything other than Barracuda or AN/ALR-94 can jam an F-22. I just wouldn't bet on it.

Well it was a Boeing 737 catbird testbed that achieved that but you are of course right and it was probably the sheer jamming power going through the APG-81 antenna that moved the needle (10 times legacy) and not sure if F-15EX APG-82 antenna will be used in the same way by EPAWSS which has its own transmitters. My point was not that the jamming by F-15EX would be optimal as it won't be due to the RCS and quite possibly low power of the bespoke antennas but that it would happen at all and be effective against the latest AESAs due to being the latest BAE EW product. Anything that reduces the enemy's detection distance will help shift the balance to that big AESA it carries.
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marauder2048

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Unread post04 Apr 2019, 02:53

sprstdlyscottsmn wrote:A sensitive enough receiver can tell it is being painted (especially if the host radar operates in a similar manner) but may not necessarily be fast enough to send a lagging signal.


Random noise waveforms result in very slow radar response times.
So any receiver capable of plucking out the noise waveform has ample time to generate a return.

sprstdlyscottsmn wrote: Plus the host radar could simply ignore a lagging return. That is an existing ECCM function.


The known techniques for countering pulse-behind DRFM all result in increased radar sidelobes
and degraded clutter cancellation.

sprstdlyscottsmn wrote: I am going to discount "predictive" as being countered 95% by the "random" nature of the Radar. So, that leaves us with noise (Barrage, or Sweep most likely) as the best bet to jam the return.


Truly random radar, by its very nature is not going to be detected by the receiver.
But it will have long integration times so it's not well suited against highly dynamic targets.
Most other "random" radars aren't.

Noise jamming is a wonderful beacon since the opposing flight can passively range on it.
That's generally not possible with deception jamming.
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marauder2048

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Unread post04 Apr 2019, 03:48

marsavian wrote:
sprstdlyscottsmn wrote:
marsavian wrote:BAE who are building EPAWSS also built the F-35 AN/ASQ-239 which detected and jammed the F-22 APG-77. If it can repeat the same trick against the Chinese/Russian AESAs then the odds get much shorter.

Remember that jamming effectiveness is related to the size of the RCS being hidden. For now, I do not assume anything other than Barracuda or AN/ALR-94 can jam an F-22. I just wouldn't bet on it.

Well it was a Boeing 737 catbird testbed that achieved that but you are of course right and it was probably the sheer jamming power going through the APG-81 antenna that moved the needle (10 times legacy) and not sure if F-15EX APG-82 antenna will be used in the same way by EPAWSS which has its own transmitters. My point was not that the jamming by F-15EX would be optimal as it won't be due to the RCS and quite possibly low power of the bespoke antennas but that it would happen at all and be effective against the latest AESAs due to being the latest BAE EW product. Anything that reduces the enemy's detection distance will help shift the balance to that big AESA it carries.



And totally unsourced. Thanks, AvWeek.

More to the point, CATBird can produce duty cycles and has the thermal management capacity that it is
difficult in practice for the F-35 or any fighter FCR to mimic. As an upper bound..sure.

It's hard for onboard transmitters to come close to the power that the FCR can achieve.
So that leaves towed decoys which have their own set of limitations.

Is EPAWSS a worthy addition to the F-15 fleet? Yes.

It is a transformational capability on which you should premise the front-line utility of a new build fleet? No.
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firesled

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Unread post19 May 2019, 05:09

I understand how the f35 is better in RCS and low level performance with a normal combat load, but I have read how F-16s wipe the floor with F-15’s until the get above 30,000 feet where the F-15’s get the upper hand and I wonder if the F-15’s don’t hold an advantage over F-35’s at very high altitudes with air to air load outs also. I can think of some very large weapons that F-35’s can’t carry internally that would benefit from being launched high and fast. Remember the F-15 is the only fighter to ever shoot down a satellite. Would the F-35 even be capable of carrying a weapon like the ASM-135?
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eloise

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Unread post19 May 2019, 05:52

marauder2048 wrote:The known techniques for countering pulse-behind DRFM all result in increased radar sidelobes
and degraded clutter cancellation.

Can you name some example?

marauder2048 wrote:Noise jamming is a wonderful beacon since the opposing flight can passively range on it.
That's generally not possible with deception jamming.

Noise jamming can be done by cruise stand in jammer such as MALD-J or SPEAR-EW
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SpudmanWP

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Unread post19 May 2019, 21:29

firesled wrote:I understand how the f35 is better in RCS and low level performance with a normal combat load, but I have read how F-16s wipe the floor with F-15’s until the get above 30,000 feet where the F-15’s get the upper hand and I wonder if the F-15’s don’t hold an advantage over F-35’s at very high altitudes with air to air load outs also.

The F-35 will always have the SA and VLO advantage.

firesled wrote:Would the F-35 even be capable of carrying a weapon like the ASM-135?

The inner pylons of the F-35 are rates for 5k so that should be easily doable.
"The early bird gets the worm but the second mouse gets the cheese."
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marauder2048

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Unread post21 May 2019, 02:38

eloise wrote:
marauder2048 wrote:The known techniques for countering pulse-behind DRFM all result in increased radar sidelobes
and degraded clutter cancellation.

Can you name some example?


Random pulse repetition interval waveforms

Pulse diversity via orthogonal sub-pulses

eloise wrote:Noise jamming can be done by cruise stand in jammer such as MALD-J or SPEAR-EW


From memory, MALD's maximum power generation is less than 1 kW...maybe around 750 W.

And from an IADS perspective, passive ranging + forward pass was designed for this scenario
particularly as MALD is not very agile (2G* turns) so comparative cheap SAMs are useful.

Some of the loyal wingman craft are pretty agile so they strike me as better hosts.

* There were follow-on versions of MALD (MALI/LCI) that were in the 5 - 9G range.
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wrightwing

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Unread post21 May 2019, 03:08

MALD/MALD-J doesn't need to be highly maneuverable. It just needs to get emitters to emit long enough, to find/destroy them, and spoof SAMs in the interim.
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eloise

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Unread post21 May 2019, 03:30

marauder2048 wrote:Random pulse repetition interval waveforms
Pulse diversity via orthogonal sub-pulses

Random pulse repetition interval waveforms = Pulse jittering?
Pulse diversity via orthogonal sub-pulses = pulse compression?
Do you have some documents about their issue with increased radar sidelobes and degraded clutter cancellation?
I haven't seen those, and i don't think it is the problem for all kind of pulse compression
img_20161019_104629.png


marauder2048 wrote:From memory, MALD's maximum power generation is less than 1 kW...maybe around 750 W.
And from an IADS perspective, passive ranging + forward pass was designed for this scenario
particularly as MALD is not very agile (2G* turns) so comparative cheap SAMs are useful.
Some of the loyal wingman craft are pretty agile so they strike me as better hosts.
* There were follow-on versions of MALD (MALI/LCI) that were in the 5 - 9G range.

I can't find any documents about MALD jamming output, i really appreciate if you can give some.
Nevertheless, It is unnecessary for MALD to have high jamming output. Firstly, because MALD are protecting stealth fighters, RCS is directly proportional to the jamming output required, as a result, a jammer 10,000 times weaker than normal is still very effective to protect stealth aircraft (0.001 m2 vs 10 m2). Secondly, because MALD-J and SPEAR-EW are supress stand-in jamming platform, because signal strength degrades the further they travel, if you put the jammer closer, you will need lower output. Don't get this confused with self protection jamming where getting closer require higher output because platform reflection is stronger.
Image
Maneuver is unimportant with cooperative jamming, HOJ missiles can be lure back and forth with blinking jamming
f-35.png

nHOoVyI.png

Even better with SPEAR-EW, each F-35 can carry 8 of them internally
p1636050_main.jpg
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marauder2048

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Unread post21 May 2019, 08:05

eloise wrote:Random pulse repetition interval waveforms = Pulse jittering?
Pulse diversity via orthogonal sub-pulses = pulse compression?
Do you have some documents about their issue with increased radar sidelobes and degraded clutter cancellation?
I haven't seen those, and i don't think it is the problem for all kind of pulse compression


Pulse jittering is one form. For random PRIs:

https://arxiv.org/pdf/1601.07624.pdf

Pulse diversity limitations (and a good general overview of the state of counter-DRFM)
https://ieeexplore.ieee.org/document/7827908

eloise wrote:Nevertheless, It is unnecessary for MALD to have high jamming output. Firstly, because MALD are protecting stealth fighters, RCS is directly proportional to the jamming output required, as a result, a jammer 10,000 times weaker than normal is still very effective to protect stealth aircraft (0.001 m2 vs 10 m2). Secondly, because MALD-J and SPEAR-EW are supress stand-in jamming platform, because signal strength degrades the further they travel, if you put the jammer closer, you will need lower output. Don't get this confused with self protection jamming where getting closer require higher output because platform reflection is stronger.


Ah. I thought you were pitching MALD or SPEAR-EW as a stand-in jammer against airborne threats.
Much harder to passively range using ground based radars.

I would still argue that the response to MALD like cruise missiles is MALD-like interceptors a la
MALI/LCI but it's debatable whether they could conclude an intercept of the jammer before
the screened assets have gotten through.
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Unread post21 May 2019, 09:13

marauder2048 wrote:Pulse jittering is one form. For random PRIs:
https://arxiv.org/pdf/1601.07624.pdf

They found a way around the issue it seem
2.PNG

1.PNG


marauder2048 wrote:Pulse diversity limitations (and a good general overview of the state of counter-DRFM)
https://ieeexplore.ieee.org/document/7827908

Ah you meant range-sidelobes :doh: i thought you meant the physical sidelobes. My bad
This
Capture.PNG

rather than this:
333.PNG


marauder2048 wrote:Ah. I thought you were pitching MALD or SPEAR-EW as a stand-in jammer against airborne threats.
Much harder to passively range using ground based radars
[/quote]
Could work against airborne threat as well, and should be better because their missiles load and radar power is more limited than SAM
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Corsair1963

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Unread post29 May 2019, 03:14

Isn't the F-15 limited to Mach 1.4 when carrying external stores from it's CFT's??? Which, would be most of the time under combat conditions!
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rowbeartoe

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Unread post30 May 2019, 07:38

Obviously if we had a lot more F-22's this F-15x option would never happen.

Question- with interception speed of F15X vs F-35. I keep reading the Mach 1.4 limit of F-15 with a practical configuration but at what altitude? My understanding is a clean F-15C with the older engines could do Mach 1.2 at sea level and 2.5+ at altitude (probably above 36,000 feet). With the F-35A max speed of Mach 1.6 (at altitude?) with (weapons?) I have a hard time believing that an F-35 would be able to reach a certain destination (say another 9/11 get your butt here moment happens) faster than an old F-15 or the improved F-15X proposal (with whatever engines those are).

That said, the F-35 is clearly a better fighter in most situations thanks to stealth and situational awareness networking. But as an interceptor it just seems hard to believe the F-35 would be faster. And I do like the idea of an F-15X being a missile carrier working in coordination with the F-35/F22 fleet should we ever come in some kind of major air to air battle.

Another thing I keep reading is that the F-15 never exceeded Mach 1.4 in combat. My question still stands- that doesn't mean it can't exceed it right and at what altitude are we talking? In IRAQ some of those fights were at low altitude I believe.

I find myself having a hard time focusing- so I guess I'm asking (I'm no expert, not a pilot, engineer etc.) as an interceptor isn't the F-15X better in that role than an F-35. Example a 9/11 thing, a group of bogies off the coast of California or New York. Intercept quickly! What's better if we have no F-22 available.

Thank you everyone! I love this site- and the F-16 is my favorite Jet still. hehehe. :)
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Corsair1963

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Unread post30 May 2019, 08:22

rowbeartoe wrote:Obviously if we had a lot more F-22's this F-15x option would never happen.

Question- with interception speed of F15X vs F-35. I keep reading the Mach 1.4 limit of F-15 with a practical configuration but at what altitude? My understanding is a clean F-15C with the older engines could do Mach 1.2 at sea level and 2.5+ at altitude (probably above 36,000 feet). With the F-35A max speed of Mach 1.6 (at altitude?) with (weapons?) I have a hard time believing that an F-35 would be able to reach a certain destination (say another 9/11 get your butt here moment happens) faster than an old F-15 or the improved F-15X proposal (with whatever engines those are).

That said, the F-35 is clearly a better fighter in most situations thanks to stealth and situational awareness networking. But as an interceptor it just seems hard to believe the F-35 would be faster. And I do like the idea of an F-15X being a missile carrier working in coordination with the F-35/F22 fleet should we ever come in some kind of major air to air battle.

Another thing I keep reading is that the F-15 never exceeded Mach 1.4 in combat. My question still stands- that doesn't mean it can't exceed it right and at what altitude are we talking? In IRAQ some of those fights were at low altitude I believe.

I find myself having a hard time focusing- so I guess I'm asking (I'm no expert, not a pilot, engineer etc.) as an interceptor isn't the F-15X better in that role than an F-35. Example a 9/11 thing, a group of bogies off the coast of California or New York. Intercept quickly! What's better if we have no F-22 available.

Thank you everyone! I love this site- and the F-16 is my favorite Jet still. hehehe. :)


In the real world no F-15 ever remotely get's close to Mach 2.5! :doh: As a matter of fact a number of F-15 pilots have stated they have never exceeded Mach 1.4 - 1.5 during their entire careers.

Honestly, in the "Real World" the F-35A is actually faster than the F-15C/E/EX with a Combat Load. Which, the critics conveniently overlook.......

If, you load up an F-35A vs F-15C/E/EX for an Air Superiority Mission. The Lightning II will eat the Eagle for lunch everyday and twice on Sunday.
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Unread post30 May 2019, 15:19

Have read that the best an Eagle can do is mach 2.2 at high altitude. Bear in mind that's completely clean and was probably done some years ago, in the Eagle's youth. The big motors are far more useful in acceleration during air to air combat and for lifting heavy loads to altitude.

It's a great airframe and has served the nation exceptionally well. But its day has passed, and the F-35 is clearly a superior fighter. Has it all over the Eagle in speed (useful, combat loaded speed), maneuverability, sensors/SA and even cost per unit. The cost per flight hour is currently higher but I fully expect it to decline in coming years.

You will hear of the new F-15EX being faster, able to carry a heavier weapons load etc., but these are half truths at best. The F-35 is rolling off production lines now, and LM has capacity to deliver many more after being given the word/money. Let's retire the Eagle with a 104-0 air to air record, and send it out undefeated. Because keeping them around much longer achieves the same thing as most athletes who "come out of retirement".

Invariably, it tarnishes their legacy...
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