Lockheed Martin F-22 Raptor

So what is this optical equipment for on the F-22? An IRST that should have been included on the ATF program from day one?
 
FighterJock said:
So what is this optical equipment for on the F-22? An IRST that should have been included on the ATF program from day one?
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It's the exact same image as in the previous page. The advanced IRST requirement was dropped during Dem/Val, and on the F-22 the system would initially have been dual sensors at the wing roots, which was later moved a single one under the nose. A requirement in EMD was later added to retain that space and cooling for future addition. Evidently that space is no longer available, perhaps repurposed for something else, hence these specially shaped pods.

It's certainly not as ideal as an internal system, which would require a more expensive design and retrofit (the funding for this effort is limited to a Middle Tier of Acquisition [MTA] to facilitate rapid prototyping, after all), although the impact can be mitigated through careful shaping. The pods also carries some EW equipment, so despite some tradeoffs it's an overall increase in capability and survivability. Stealthy external stores have been investigated since the FB-22 studies in the early to mid-2000s.

Many upcoming F-22 upgrades are directly linked to NGAD as well, so some components are likely to carry over although probably packaged internally as its a clean-sheet design airframe.
 
Interesting bit in this old article:

While any possibility of buying the Lockheed Martin F-22 Raptor has repeatedly been dismissed by politicians over the past decade or more as being too expensive, too inflexible and “not for sale”, following an informal RFI there was a proposal put to the Australian government by the US early in the AIR 6000 process for an export-configured Raptor which would have satisfied US ITARS arms export control laws while still providing a high-end capability. But the proposal was never seriously considered for a number of reasons, including the fact the aircraft was designed primarily for the air supremacy mission with only a secondary strike role and had no maritime strike capability. In addition, apart from the high unit cost, there would have also been a huge additional investment required as lead customer for the development of the export version.
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icyplanetnhc (Steve) said:
It's the exact same image as in the previous page. The advanced IRST requirement was dropped during Dem/Val, and on the F-22 the system would initially have been dual sensors at the wing roots, which was later moved a single one under the nose. A requirement in EMD was later added to retain that space and cooling for future addition. Evidently that space is no longer available, perhaps repurposed for something else, hence these specially shaped pods.
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Weren't there photos of modded testbeds sporting IRST systems way back when? To clarify, they had them inbuilt in the roots, noses, and other areas of the testbeds.
 
It seems unlikely triangulation would be possible over such a short distance with that little distance between the sensors. Perhaps there was some kind of funky phase or time of arrival analysis you could derive range. I cannot fathom what the mechanism would be but it might be possible. If nothing else superior field of view as noted above.
 
Josh_TN said:
It seems unlikely triangulation would be possible over such a short distance with that little distance between the sensors. Perhaps there was some kind of funky phase or time of arrival analysis you could derive range. I cannot fathom what the mechanism would be but it might be possible. If nothing else superior field of view as noted above.
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If the pods do also have an EW function as suggested previously
icyplanetnhc (Steve) said:
The pods also carries some EW equipment, so despite some tradeoffs it's an overall increase in capability and survivability.
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then FOV will also be important especially as a pod that size is likely for high bands.
 
Desert Watchdog said:
Weren't there photos of modded testbeds sporting IRST systems way back when? To clarify, they had them inbuilt in the roots, noses, and other areas of the testbeds.
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In a publication by Code One documenting the evolution of the F-22 design, the deletion of the IRST at the wing roots was cited as the reason for the leading edge flaps being moved further inboard compared to the YF-22. Later on a low-observable window for an IRST system had been tested during EMD (picture here), and the bulkheads of the F-22's forward fuselage do have inverted v-shape cutouts ostensibly to support an ventral sensor. However, at this point it may not be viewed as economical. Again, funding for sensor enhancements has been limited as an Middle Tier of Acquisition program in order to do things like rapidly prototype the systems. I suppose we'll see if there will be further mods depending on how long the F-22 remains in service, especially in light of the crewed PCA fighter component of NGAD being reevaluated.

For some interesting trivia, the F-22 IRST sensor (I think the term for it originally was EOSS, electro-optical sensor system) during Dem/Val was being developed by General Electric, while the current system is being developed by Raytheon.

If the funding isn't an issue, then I think there are some interesting things you can do to the airframe. Per Jay Miller's 2005 book on the F-22, there are provisions for more fuel volume in saddle and fin tanks, which suggest that there is unused internal volume due to budget constraints during EMD.
 
quellish said:
Why would you want to apply a new RAM coating? What problem would it solve?
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Maintenance and logistics. Use the same stuff as F-35 and/or B-21 (assuming that Lightning and Raider use the same RAM).

Especially being able to take less time for return to service after maintenance.



Josh_TN said:
It seems unlikely triangulation would be possible over such a short distance with that little distance between the sensors. Perhaps there was some kind of funky phase or time of arrival analysis you could derive range. I cannot fathom what the mechanism would be but it might be possible. If nothing else superior field of view as noted above.
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You can get naval-gunfire-quality triangulation over 50km with a 10m spacing.
 
quellish said:
Why do you say the podded IRST is being developed by Raytheon?
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Recent Raytheon contract award broadly aligns with the amount for Group B procurement funding under the Sensor Enhancement line item for the F-22. The contract language even spells out Group B hardware.
 
icyplanetnhc (Steve) said:
Recent Raytheon contract award broadly aligns with the amount for Group B procurement funding under the Sensor Enhancement line item for the F-22. The contract language even spells out Group B hardware.
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The F-22 has a lot of sensors, and the Sensor Enhancement Program covers nearly all of them. More than one contractor is involved and hardware has already been delivered for some aspects of the program as upgrade kits. In addition to sensors themselves, an effort to add an open systems architecture layer to the F-22 is part of the Sensor Enhancement Program.

The Raytheon contract award information (FA8611-24-C-B001) has not actually been published that I can find. Only an award announcement.

And on a side note, an LDTP EMD contract is expected to be awarded on Halloween.
 
Alex Hollings from Sandbox has just uploaded this video concerning USAF plans for the F-22:


With the future of America’s next air superiority fighter now in question, America’s king of the skies, the F-22 Raptor, is set to extend its reign well into the 2030s, thanks to a slew of upgrades already underway — and the list keeps getting longer, with some $10.9 billion allocated to improving the Raptor fleet by 2031.
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But with only 150 F-22s in combat service... Can improving this endangered species of a fighter really be enough to maintain America's air superiority edge?
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I have to be honest, I'm not impressed by the signal-to-noise ratio of the Sandboxx videos.

siegecrossbow said:
If from the get go they had common components with the F-35 it would be a lot easier to modify/maintain the existing fleet.
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Incorporating the avionics of the F-35 would have required some rather substantial re-engineering of the F-22's systems since both have such highly integrated architectures. It wouldn't have been worthwhile unless the we got the full 381 aircraft that the Air Force wanted rather than being truncated at 195, and the longer production run could have supported improved variants. Even so, it's not like the F-35's avionics have been particularly conducive to upgrades either thus far, and as it currently stands, it's the F-22 that's actually outpacing the F-35 in terms of faster updates and releases.
 
What does the cost of a flight hour consist of?
The F-22 has a full life of 8000 hours, the cost of the machine for the US Air Force is 168 million. $
thus, an hour of resource costs 168 million $ : 8000 h = 21000 $
fuel cost in the USA in April 7.5 $ / gallon or 1.98 $/ kg
fuel consumption 3600 kg / h 3600 kg * 1.98 $/kg ~ 7000 $/h
$21,000 (resource) + $7000 (fuel) = $28,000$
68,362 left - $ 28,000 = $ 40,362
What can be included here? pilot's salary, technicians' salary, maintenance...
 
paralay said:
What does the cost of a flight hour consist of?
The F-22 has a full life of 8000 hours, the cost of the machine for the US Air Force is 168 million. $
thus, an hour of resource costs 168 million $ : 8000 h = 21000 $
fuel cost in the USA in April 7.5 $ / gallon or 1.98 $/ kg
fuel consumption 3600 kg / h 3600 kg * 1.98 $/kg ~ 7000 $/h
$21,000 (resource) + $7000 (fuel) = $28,000$
68,362 left - $ 28,000 = $ 40,362
What can be included here? pilot's salary, technicians' salary, maintenance...
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This is different for each country apparently. There is no single equation for this.
 
paralay said:
What does the cost of a flight hour consist of?
The F-22 has a full life of 8000 hours, the cost of the machine for the US Air Force is 168 million. $
thus, an hour of resource costs 168 million $ : 8000 h = 21000 $
fuel cost in the USA in April 7.5 $ / gallon or 1.98 $/ kg
fuel consumption 3600 kg / h 3600 kg * 1.98 $/kg ~ 7000 $/h
$21,000 (resource) + $7000 (fuel) = $28,000$
68,362 left - $ 28,000 = $ 40,362
What can be included here? pilot's salary, technicians' salary, maintenance...
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There's a number of maintenance-hours that have to happen after every flight, and that's divided up across however many specialties and trades are needed.

Plus the schools to teach them all, for airframe-specific things like the engines, electronics, and IIRC RAM structures/coatings
 
Scott Kenny said:
quellish said:
dark sidius said:
Arjen said:
Are you suggesting 'a fresh coat of paint', or an entirely different application of RAM in line with F-35 practices?

Genuine question - would the latter be feasible on the F-22?
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A new RAm paint.
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Why would you want to apply a new RAM coating? What problem would it solve?
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Maintenance and logistics. Use the same stuff as F-35 and/or B-21 (assuming that Lightning and Raider use the same RAM).
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Much of the RAM material of the F-35 is literally "baked into" the composite material which comprises most of the wing and fuselage skin. It only degrades if the aircraft skin is being abraded away.

The only way to "update the F-22 with this" would be to replace the wing and fuselage skin material with new composite materials... which would comprise a complete rebuild of each F-22.

It would be easier (and likely cheaper) to build all-new airframes with composite/RAM skins and then stuff the F-22's engines, systems, and avionics into it.
 
A new “trade study” will capture more detailed data about how the F-22 is actually flown, better identifying strain on engine components and providing a new “single source of truth” for insight on the health of the fleet, Cooper said. The aim: “To derive learnings much quicker and help us to evaluate and optimize needed changes to the engine or aircraft in a more timely manner,” Cooper said.

“There was a major difference in the way that engine part life assumptions were calculated and how the operators were actually flying the engine,” Cooper said. “And what we were able to do is a very significant software update to really extract greater kinetic performance out of the engine.”
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www.airandspaceforces.com

Pratt's New Software Aims to Extend Life, Enhance Performance of F-22 Engines | Air & Space Forces Magazine

Pratt & Whitney hopes to keep the F-22 relevant by better tracking when parts and maintenance are really needed, and through 3-D printing.
www.airandspaceforces.com www.airandspaceforces.com
 
BDF said:
I know it's been said that the F-22 lost fuel during EMD but I can't seem to find any evidence of it
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This was originally in the YF120 thread but I'll respond here as it's more relevant. On this point, when I reviewed Jay Miller's 2005 publication (ISBN 1-85780-158-X) on the F-22, it was mentioned on page 111 that for the aircraft's fuel system, all production aircraft had provisions for saddle and fin tanks, which may indicate that these were not installed during EMD to cut costs. I'd imagine that the fin tanks would likely have been vent tanks, which would then open up additional usable fuel volume elsewhere. I'm not quite sure where the saddle tank would be, however.
 
icyplanetnhc (Steve) said:
This was originally in the YF120 thread but I'll respond here as it's more relevant. On this point, when I reviewed Jay Miller's 2005 publication (ISBN 1-85780-158-X) on the F-22, it was mentioned on page 111 that for the aircraft's fuel system, all production aircraft had provisions for saddle and fin tanks, which may indicate that these were not installed during EMD to cut costs. I'd imagine that the fin tanks would likely have been vent tanks, which would then open up additional usable fuel volume elsewhere. I'm not quite sure where the saddle tank would be, however.
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Hmm, also wonder where that would be...
main-qimg-c0f7162a08c5e03c081259db139b379d.jpeg
 
Thanks, haven't seen that T.O. chart in a while and I should have referenced it. It would appear that the saddle tanks most likely refer to A-3R and A-3L. Incidentally, the internal fuel volume from this document is around 20,650 lbs, and removing A-3R/L would bring that down to about 19,614 lbs, which is still greater than the published number of about 18,000 lbs internal. Perhaps this is also taking into account the vent tank volume that would have been available for usable fuel had the fin tanks been installed.
 
Interesting, so looks like I was wrong and the F-22 indeed was originally meant to carry 20,650lbs of fuel. Shame the fuel was reduced because every bit of range is helpful in INDOPACOM. Also BDF mentioned that using CAD to measure the tank volume the EMD F-23 would have about 24% more internal fuel volume than YF-23 which has about 18,000lbs so that's about 22,320lbs, which is not dramatically more than the F-22 if those tanks in the vertical fin and saddle weren't cut. And it's possible the EMD F-23 would have suffered similarly if selected.
 
It's possible but I'd caution people against assuming that the F-23 would have been affected the exact same way as the F-22 since Northrop may have went with a different route from Lockheed based on their trade studies. It's one of the pitfalls of these "what-if" alternate histories; it may, or may not, we don't know for certain. That said, I think it's reasonable to assume that at the time of EMD selection in 1991, the nominal internal fuel loads for the F-22 and F-23 weren't that different.
 
icyplanetnhc (Steve) said:
It's possible but I'd caution people against assuming that the F-23 would have been affected the exact same way as the F-22 since Northrop may have went with a different route from Lockheed based on their trade studies. It's one of the pitfalls of these "what-if" alternate histories; it may, or may not, we don't know for certain. That said, I think it's reasonable to assume that at the time of EMD selection in 1991, the nominal internal fuel loads for the F-22 and F-23 weren't that different.
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Their flown design appears to have been much closer to their final design than the F-22. It also had more fuel as I recall. The YF-22 also had quite a bit more fuel than the F-22A. If you look at the bottom, aft of the two you can see the F-22A is much slimmed down.
 
sferrin said:
Their flown design appears to have been much closer to their final design than the F-22. It also had more fuel as I recall. The YF-22 also had quite a bit more fuel than the F-22A. If you look at the bottom, aft of the two you can see the F-22A is much slimmed down.
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Eh, while the F-23 may had more fuel than the F-22, I don't think it was substantial. @BDF did loft the fuel tank cross sections from the F-23 EMD DWGs, and I think he came up with an increase of roughly 30% in the fuselage fuel tank volume, while the wing tanks remained about the same. With the YF-23 having about 18,000 lbs of fuel (Paul Metz's book stated that it had a bit more than an F-15C with a CL tank), this works out to be about 21,000 to 22,000 lbs of fuel, which isn't too different from the F-22, had it retained its original 20,650 lbs of fuel with its fin and saddle tanks. Also, I think it's important to note that the YF-23 was a pretty well refined and understood design since the basic shape and planform remained largely the same since 1985 for Northrop's HSF design, which partly explains the performance disparity from the YF-22. The F-22 design was largely able to catch up once it had the much needed refinement.

While oft repeated, I don't think the F-22 actually has less fuel than the YF-22. The F-22's fuselage slimming down and being streamlined has more to do with the fact that Lockheed/Boeing/General Dynamics was able to substantially refine the design after the YF-22 lines were frozen. The prototype shape was frankly quite immature since the Lockheed team did a complete configuration redesign starting in summer 1987, which wasn't a lot of time before the prototypes (technically more like XF demonstrators) had to be frozen in May 1988 to begin fabrication. I think one of the major changes was in the cooling method for divert nozzle section that allowed it to be shrunken considerably (compare the YF119 nozzle to the EMD/production F119 nozzle, external vs internal cooling channels), which then allowed the aft fuselage to slim down accordingly. I think this is because even after deletion of the thrust reverser requirement, the original Lockheed divergent nozzle still had some provisions for that so it was bulkier than needed. The vertical fin size was also considerably reduced on the F-22 to reduce drag. Again, I think any reduction in fuel volume has more to do with the fin and saddle tanks being cut during EMD.
 
icyplanetnhc (Steve) said:
This was originally in the YF120 thread but I'll respond here as it's more relevant. On this point, when I reviewed Jay Miller's 2005 publication (ISBN 1-85780-158-X) on the F-22, it was mentioned on page 111 that for the aircraft's fuel system, all production aircraft had provisions for saddle and fin tanks, which may indicate that these were not installed during EMD to cut costs. I'd imagine that the fin tanks would likely have been vent tanks, which would then open up additional usable fuel volume elsewhere. I'm not quite sure where the saddle tank would be, however.
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To be fair, my point really revolves around the commonly used axiom that the Raptor lost fuel from the prototypes; which of course implies that the YF-22 had much more fuel. It was often stated that the YF-22 had 24klbs and the YF-23 had 25Klbs of internal fuel. We know from Metz's book that is not true. Certainly not with the YF-23 PAVs.

The USAF TO might be showing total volume which includes ullage volume, vent tank(s) and unusable/trapped fuel. As I recall usable fuel is around 10-15% of total fuel weight as a rough rule of thumb. So it would not surprise me that 20,650lbs of tank volume equates to the ~18K+lbs of usable fuel the Raptor is credited for.

I think I misspoke when I posted about compared volumes of the PAV to DP231 in the General Arrangement drawings for the F-23A. It was a 28% difference. I went back and checked. Note that I did not include the vent tanks on either vehicle which may or may not be accurate. In a Pac Theater scenario the potential difference (F-22A vs F-23A) is interesting but still not tactically significant IMO. FWIW.
 
BDF said:
The USAF TO might be showing total volume which includes ullage volume, vent tank(s) and unusable/trapped fuel. As I recall usable fuel is around 10-15% of total fuel weight as a rough rule of thumb. So it would not surprise me that 20,650lbs of tank volume equates to the ~18K+lbs of usable fuel the Raptor is credited for.
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More precisely, I think according to Raymer (or is it Nicolai? have to check), it's 10-15% of total fuel tank volume that's dedicated to plumbing and pumping hardware, while the T.O. does list fuel weight in lbs which is why I'm inclined to believe it's talking about usable fuel. That said, maintainers can correct me if I'm wrong. In any case, for the F-22, it may not have necessarily lost fuel from the YF-22, but it likely did lose fuel during EMD due to budget pressures, and removing the vent tanks from the fins likely caused a reduction in usable fuel volume elsewhere.
 
icyplanetnhc (Steve) said:
I think one of the major changes was in the cooling method for divert nozzle section that allowed it to be shrunken considerably (compare the YF119 nozzle to the EMD/production F119 nozzle, external vs internal cooling channels), which then allowed the aft fuselage to slim down accordingly. I think this is because even after deletion of the thrust reverser requirement, the original Lockheed divergent nozzle still had some provisions for that so it was bulkier than needed.
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This is pretty much correct. The YF119 nozzles (both versions) retained the thrust reverser architecture, basically deleting the reverser exit doors on the top & bottom of the nozzle static structure, and the convergent nozzle segment travel was limited since it wasn’t necessary to close off the flow to the rear while reversing. It was essentially the same architecture as the F-15 /F100 SMTD vectoring / reversing nozzle.

The F119 production nozzle is a completely different configuration, optimized for weight, performance, and signature.
 
Dreamfighter said:
IIRC, some fuel-capacity was reduced during EMD to compensate for some airframe weight increase.
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I don't recall the weight increase as being associated with the reduction in fuel volume during EMD, and apparently the provisions for those fuel tanks still exist in the production jets. The main weight increase was due to ballistic survivability, where after the results of live fire tests, the wing design changed from all composite spars to a combination of composite and titanium spars, thus increasing weight. The contractor empty weight (that is, without the engines and other contractor/furnished equipment) increased by 610 kg to 14,365 kg (31,670 lbs), while operating empty weight (including all GFE and fluids/POLs) was always considered to be in the 40,000 lb range, now around 43,340 lbs (19,659 kg) with the two F119 engines being the heaviest component of that additional weight.

Per Flight International in 1995, part of the weight growth was also associated with the desire to contain costs.
 
icyplanetnhc (Steve) said:
I don't recall the weight increase as being associated with the reduction in fuel volume during EMD, and apparently the provisions for those fuel tanks still exist in the production jets. The main weight increase was due to ballistic survivability, where after the results of live fire tests, the wing design changed from all composite spars to a combination of composite and titanium spars, thus increasing weight. The contractor empty weight (that is, without the engines and other contractor/furnished equipment) increased by 610 kg to 14,365 kg (31,670 lbs), while operating empty weight (including all GFE and fluids/POLs) was always considered to be in the 40,000 lb range, now around 43,340 lbs (19,659 kg) with the two F119 engines being the heaviest component of that additional weight.

Per Flight International in 1995, part of the weight growth was also associated with the desire to contain costs.
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I don´t remember all the exact details (I do remember some more usage of titanium and less composites) about the causes for weight increase (I´ve lost lots of data/documents over the past 30 years), but I remember (hopefully in a correct way) a weight increase during EMD was the cause for a decision to somewhat reduce/relax the total fuel volume/load, in order not to have to relax some other requirements under certain conditions. However, the Flight Int. article you linked states the USAF was considering relaxing somewhat the sustained turn performance to compensate for the weight increase. Maybe there was another (bit of) weight increase then the one referred to in the article, or they changed minds about what to trade for what, I can´t remember...
 
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"The F/A-22 airframe weight has been unstable and has grown during most of the EMD period. At the beginning of the F/A-22 EMD program, both the Design-to-Weight (DTW) and the parametric weight estimate were significantly lower than the current weight of the aircraft, or Achieved-to-Date (ATD) weight. The F/A22 DTW increased and grew more realistic and converged with the ATD as the program progressed. Figure 3.6 depicts the ATD weight from the beginning of the program until September 2002."

"The figure shows the contractor responsible weight changes over time. After the initial drop of 21 percent, the weight has grown by 11 percent since the program’s preliminary design review (PDR) in April 1993. The data also indicate that considerable efforts may have been made to bring down the F/A-22 airframe weight estimate before the PDR because the weight dropped about 5 percent in the six months preceding PDR. The figure also shows that, after this initial drop, the weight steadily increased ever since. It is interesting to note that the weight dropped just before and increased right afte both the PDR and critical design review. Significant weight decrease just before a major design review reflects unstable airframe design.In contrast to the F/A-22, the F/A-18E/F airframe weight has remained relatively stable, with a minor 2 percent growth during EMD."


pages 37-38
 

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