F-15EX

[sprstdlyscottsmn]

Garrya, coming out later does not mean newer tech. Check charlielima223 comment above. The APG-82 is a hodgepodge of parts from older planes. Also the backend matters as much or more than the front end. The only thing a big dish alone gets you is gain. What is the available system power for transmission? How much power throughput can the components handle?
How good is the computer in the backend for processing the signals?

I think you are right on the money for how an AIM-120D3 from an EX can have the longest range of any fighter in US inventory, but it would be very conditional. Remove the CFTs, use body mount AIM-120s only, get going 2.2M at 60kft, and THEN you can fire like a maxxed out Raptor. In everyday conditions I would count on the Raptor to do it better.

[milosh]

Garrya, coming out later does not mean newer tech. Check charlielima223 comment above. The APG-82 is a hodgepodge of parts from older planes. Also the backend matters as much or more than the front end. The only thing a big dish alone gets you is gain. What is the available system power for transmission? How much power throughput can the components handle?
How good is the computer in the backend for processing the signals?

I don't think it lack data processing power:

https://www.youtube.com/watch?v=zKT43rU45YE

87 billion ips, well that is almost 45x what original F-22 CIP could do.

Also I doubt there is lack of electricity for powerful AESA radar, but what could be problem is cooling. F-22 do have excellent cooling system which have heatsinks inside intakes (could be wrong though) so F-22 don't rely just on cooling radar with heatsink in fuel tank.

In case of F-15 it would be interesting to read how they cool AESA radar.

One "advantage" of F-15EX radar it don't need LPI mode as much as F-22 radar. F-15EX is big on radar even without weapons so LPI mode is much less MUST HAVE so F-15EX and burn with its radar as crazy.

If cooling is solved I see F-15EX when very long range missile came as something like MiG-31.

[garrya]

Garrya, coming out later does not mean newer tech. Check charlielima223 comment above. The APG-82 is a hodgepodge of parts from older planes. Also the backend matters as much or more than the front end. The only thing a big dish alone gets you is gain. What is the available system power for transmission? How much power throughput can the components handle?
How good is the computer in the backend for processing the signals.

Let me first summary the recent radar development on F-15.
APG-63v1 is a mechanical scanned radar
APG-63v2 is the first AESA on F-15.
APG-63v3 is upgraded APG-79 front end merged with APG-63v1 back end and merged with APG-63v2 software.
APG-82 is basically APG-79 back end with APG-63v3 front end.
In short, APG-82 is basically a much bigger APG-79.
APG-81 and APG-79 were introduced around the same period. APG-81 made by Northrup Grumman while APG-79 made by Raytheon. So it could be expected that their hardware are generally similar enough (as in I don't expect there is significant technology disparity here).

Because we are talking about AESA here, big aperture give you more transmitting output also since it mean more T/R modules can be fitted. Bigger aperture mean smaller beam which result in the power being more focused as well. So in term of output and directivity, I would expect that APG-82> APG-77v1 > APG-81 > APG-79.

Regarding how much power the system can handle, it depend on cooling. In that aspect, F-15EX is just as good as F-35
Currently, at F-35 Block 3F, the F135 engine is supplying 30kW of cooling bleed flow. However, this requires the engine to run hotter and faster to offset this diversion of core airflow, which reduces hot section life, driving the power module back to depot sooner than planned.It plausible that the small cooling scope on top of the aircraft can provide another 3-5 kW of cooling by ambient air.

At the same time, Kendall has proposed reengining the F-35. The Pratt & Whitney F135 is meeting specifications, but Block 4 electronic upgrades risk overwhelming the power and thermal management system. Pratt designed the 43,000-lb.-thrust engine to provide bleed air from the compressor to cool the onboard electronics. But the Block 3F electronics introduced in 2016 already demand twice the optimal 15 kW of bleed-air offtake. The Block 4 upgrades, which include a new core processor, will require a 47-kW offtake from the compressor.

The Air Force is debating whether to upgrade the F135 or shift to the product of the Advanced Engine Technology Development program. The candidates include the GE Aviation XA100 or Pratt XA101 turbofans, which feature adaptive controls for bypass flow that can offer at least a doubling of cooling capacity compared with the F135.

https://aviationweek.com/defense-space/ ... -structure

For comparison, legacy F-15E has 35 kW cooling capacity with potential to growth to 52 kW

769C21F0-4E06-4747-B92C-117B6D6A645C.png (229.27 KiB) Viewed 2738 times

[wrightwing]

In term of aperture, APG-82 has bigger aperture than APG-77, APG-81, APG-79 and APG-80. It also come out much later. So logically, it should have longer range. Of course, that doesn't mean F-15EX can attack stealth aircraft before it get attacked. Since F-15 RCS is pretty huge so it will be detected from very long range. However, logically, let say if F-22 can detect a Rafale from 200 km by APG-77 then logically F-15EX will detect that same Rafale from distance even greater than 200 km.
Furthermore, since F-15 top speed is greater than all other aircraft in USAF. If you give it a very big target, like an AWACS or Mig-31 and give the F-15 the time to accelerate to top speed. Then it would come at no surprise that F-15 will be able to attack from much greater distance compared to other USAF fighters.

The F-15 doesn't have a higher top speed than an F-22 or F-35, in a combat configuration. Aperture size isn't the only factor in detection ranges. Power, gain, sensitivity, signal to noise ratio, filtering/signal processing, etc....are all part of the equation, too.

[Corsair1963]

It's interesting that the USAF (i.e. ANG) is the only customer for the F-15EX. Yet, they already want to cut back their order.


Funny, that hardly anybody talks about that........

[sprstdlyscottsmn]

APG-81 and APG-79 were introduced around the same period. APG-81 made by Northrup Grumman while APG-79 made by Raytheon. So it could be expected that their hardware are generally similar enough (as in I don't expect there is significant technology disparity here).

I want to address this part the most. Coming out at the same time does not make them equal. The F-35 program funded the APG-81 and it became a no-holds barred system of systems that forced the F-22 to upgrade its radar to keep up. The F/A-18E program funded the APG-79 and the ENTIRE basis of the Super Hornet was "look how cheap and affordable we are." If you have to design two identically sized radars but you can afford the more expensive components for one that one will be leaps and bounds better in all aspects. Smaller components that can handle greater throughput and are more heat resistant and be more reliable etc etc etc. These were all factors I have dealt with professionally.

I will also address your infographics. The F-35 has 400KW power generation available, which puts the 150 of the EX to shame.

F-35 electricity generation.PNG (254.34 KiB) Viewed 2617 times

The EX still has to run the same EW kit (with smaller antennas) as the F-35, so that will not be cheap power wise. That massive mission computer will cost a ton power wise. So either the F-15EX is low on power, or the F-35 has twice as much as it needs.

[sprstdlyscottsmn]

It's interesting that the USAF (i.e. ANG) is the only customer for the F-15EX. Yet, they already want to cut back their order.


Funny, that hardly anybody talks about that........

Not exactly. The Saudi and Qatar already funded most of the development and the Isrealis are on the line for them too, just minus the EPAWSS.

[Corsair1963]

It's interesting that the USAF (i.e. ANG) is the only customer for the F-15EX. Yet, they already want to cut back their order.


Funny, that hardly anybody talks about that........

Not exactly. The Saudi and Qatar already funded most of the development and the Isrealis are on the line for them too, just minus the EPAWSS.

While, the F-15EX is clearly related to the earlier F-15SA (Saudi) and F-15QA (Qatar). They don't have any new export orders either....and Israel has rejected the type. (F-15EX)


It's worth noting that the whole reason for acquiring the F-15EX was for a quick replacement of the retiring F-15Cs. Yet, so far at least all of the retiring F-15Cs within the USAF have been replaced with the F-35As. While, the ANG is pretty much 50/50.....(again so far)

My guess is sooner or later the F-15EXs will just supplement and/or replace some of the remaining F-15Es still in US Inventory.

[garrya]

I want to address this part the most. Coming out at the same time does not make them equal. The F-35 program funded the APG-81 and it became a no-holds barred system of systems that forced the F-22 to upgrade its radar to keep up. The F/A-18E program funded the APG-79 and the ENTIRE basis of the Super Hornet was "look how cheap and affordable we are." If you have to design two identically sized radars but you can afford the more expensive components for one that one will be leaps and bounds better in all aspects. Smaller components that can handle greater throughput and are more heat resistant and be more reliable etc etc etc. These were all factors I have dealt with professionally.

IIRCC, both F-35 and F-18E/F did have to emphasize the affordable aspect(F-35 due to the lesson from F-22). Though I incline to agree with you that APG-81 is better than APG-79. Not only because it has much bigger aperture, but also because it has better central processor. I recalled that APG-81 even won an award for super performance in jamming.
Still APG-82 is supposed to be an upgraded APG-79 rather than an exact replica.

I will also address your infographics. The F-35 has 400KW power generation available, which puts the 150 of the EX to shame.
The EX still has to run the same EW kit (with smaller antennas) as the F-35, so that will not be cheap power wise. That massive mission computer will cost a ton power wise. So either the F-15EX is low on power, or the F-35 has twice as much as it needs.

IMHO, F-35 mission computer + DAS + electronic actuator make it consuming more electrical power than F-15EX. Or F-35 simply has a lot of excess power for future avionics and DEW. Since radar of both aircraft will be hard gated by their cooling capacity. There is no way either of them can even use their radar at more than 30 kW average output
That only change once F-35 get the new three stream engine( because it will double its cooling capacity)

[garrya]

The F-15 doesn't have a higher top speed than an F-22 or F-35, in a combat configuration.

Without CFT, F-15 can have higher top speed

Aperture size isn't the only factor in detection ranges. Power, gain, sensitivity, signal to noise ratio
filtering/signal processing, etc....are all part of the equation, too.

Power, gain, sensitivity, signal to noise ratio are all heavily affected by aperture area.
Regarding signal processing, the newest ICP on F-15EX is two time faster than the current ICP on F-35

https://www.aviationtoday.com/2003/09/0 ... iztOrfhCUk

That will change once the new Harris ICP being intergrated to F-35 in block 4. Then F-35 ICP will be 12.5 times faster than F-15EX ICP

[Corsair1963]

"garrya"
Without CFT, F-15 can have higher top speed

First, the F-15EX would never fly without CFT's. Second, even if it did it would still carry external stores. (weapons and fuel)


In short still not faster than a F-35........

[garrya]

"garrya"
Without CFT, F-15 can have higher top speed

First, the F-15EX would never fly without CFT's. Second, even if it did it would still carry external stores. (weapons and fuel)


In short still not faster than a F-35........

There are several F-15 charts you can look at.
Generally, F-15 loaded with AIM-120 and no CFTs is faster than F-35.

[wrightwing]

"garrya"
Without CFT, F-15 can have higher top speed

First, the F-15EX would never fly without CFT's. Second, even if it did it would still carry external stores. (weapons and fuel)


In short still not faster than a F-35........

There are several F-15 charts you can look at.
Generally, F-15 loaded with AIM-120 and no CFTs is faster than F-35.

The F-15C has never flown faster than M1.4 in combat. Could it fly faster? Yes. But even then it's not going to be flying faster than M1.6 if it hopes to have any range or persistence. This topic has been beaten to death. It simply takes too much fuel to get beyond M1.4, for it to be considered tactically relevant.

[usafr]

Which is why the USAF considers the F-22 Raptor's ability to "cruise" at mach 1.5 a "super" ability worthy of its own special name.

While others achieve < 1.5 super sonic speeds with out a full combat load of weapons and fuel, and only for a short period of time (< 5 min?), the Raptor can do 1.5 routinely and for a much longer time (> 10 min?).

Super Cuise is different from super sonic dash. Only a Raptor can super "cruise".

[f119doctor]

During F-22 flight test exploring the high speed envelope, the F-15C chase planes with centerline tank and empty pylons couldn’t stay anywhere near the test F-22. For the M2 tests, they would cruise out to the Colorado river, accelerate into the supersonic corridor up to the test conditions, and perform the load and flutter tests on the way back towards Edwards AFB. By the time they reached the end of the corridor, the F-15 would be tens of miles behind and wouldn’t be able to rejoin until the F-22 had turned around back to the east. I don’t know if the F-15 chase couldn’t keep up, or if it was just impractical to use that much fuel to try.