Image 1: Notional F-22C upgrade package.
While the enhancements described in Part
II will rectify some the inherent design deficiencies of the base F-22A - such
as range and limited computing power, additional changes are needed to ensure
the F-22 can operate in the most contested environments in the post-2030
timeframe. The key elements of any F-22C upgrade program would include
additional sensors to improve situational awareness, survivability, and munitions
integration and storage capacity. Overall, the majority of these upgrades will
assist in within visual range engagements and survivability against infrared (IR)
guided missiles. Each upgrade recommendation varies in technical complexity,
schedule, and cost which invariably will make certain upgrades more attractive
to the USAF than others.
Sensors
Sidelooking AESAs
Image 2: Proposed F-22 growth options by Karlo Copp. Image Credit: Air Power Australia & Carlo Kopp, 2006.
The existing F-22 sensor suite is arguably
the most capable of any fighter aircraft with the exception to the F-35. The
APG-77 active electronically scanned array (AESA) radar consists of at least
2,000 transmit receive modules which can detect a 1m^2 rcs target at a distance
of 150 nautical miles (nm) all the while changing its frequency 1,000 times per
second under its low probability of intercept (LPI) mode to evade emission
locator systems.[1]
The passive detection capabilities of the F-22 are arguably even more
impressive, BAE’s ALR-94 radar warning receiver (RWR) and digital electronic
warfare suite enables the F-22 to perform precise geolocation and tracking of
emitters from any direction up to 250 nm away; the details of this capability
are highly classified but it is plausible the fidelity of the geolocation
capabilities are of a high enough quality to provide target quality tracks for
weapons employment i.e. narrowband interleaved search and track (NBLST) mode.[2] However, the key to
leveraging all of the F-22’s powerful sensors – and arguably the area of
greatest difficulty to developing a fifth generation fighter, is the F-22’s
software which fuses sensor inputs and disseminates critical information for
the pilot thereby providing unmatched situational awareness of his or her
environment. Despite the already impressive capabilities of the baseline F-22A,
changes to the threat environment and USAF procurements since termination of
the production line necessitate additional upgrades to the F-22’s sensor suite.
With its current suite of sensors and
enhanced situational awareness, Raptor pilots over the skies of Syria haven
taken on battle management duties; the superior understanding of the
battlespace by Raptor pilots provides nascent airborne warning and control
(AWACS) capabilities to Coalition forces.[3] The Raptor’s command and
control (C2) role will only grow in importance should the U.S. fight in a
highly contested environment where the safety of E-3 and E-2D AWACS aircraft –
even at stand-off ranges, is not assured. Furthermore, the limited production
run of F-22 and the vast geographic expanse of likely conflict zones both the
Asia-Pacific and Europe will force a standard four ship formation of F-22’s to undertake
much more demanding combat air patrols for both offensive and defensive counter
air missions. A potential solution to expand both the F-22’s C2 capabilities
and enable small units of F-22s to cover wider areas of responsibility would be
the installation of sidelooking AESA radars which would provide much greater
horizontal and vertical coverage. Furthermore, these arrays could utilize a
lower frequency band, such as the L-band sidelooking arrays utilized on the
Su-35, to improve detection capabilities against low radar cross section
targets optimized for the X and S-band.[4]
Image 3: 2008 PO document courtesy BDF and F-16.net. Note: this document is out of date, but it does provide valuable insight towards a much longer term upgrade roadmap than the current Increment series. The desire for additional C2 and ISR capabilities is particularly noteworthy.
The F-22A’s existing superstructure
has provisions for sidelooking phased array radars as a growth option for
further development.[5] The upgrade would not be
necessary for every F-22, even upgrading only the flight lead’s and element
lead’s aircraft within a four aircraft formation would enable much greater operational
flexibility. For example, during the Persian Gulf war, it was standard practice
for two pairs of F-15Cs to fly in the beyond visual range fighting formation
known as the “Wall of Eagles”:
Using their
radars, all formation members searched the area ahead of them usually in a 120
degree azimuth sweep, which covered an 80 nm wide arc at 40 miles off the nose.
With as much as five miles between the wingmen, at 40 nm the entire formation
searched an 85-mile-wide swath, making it difficult for an adversary to
outflank the formation, or escape detection…Each two-ship element in the ‘Wall
of Eagles’ formation searched with their radars from the earth’s surface to the
base of the contrail level, the two elements ensuring overlapping coverage.
Additionally, the wingman visually scanned the contrail layer for telltale
signs of aircraft approach in that altitude band. – F-15C Eagle vs Mig-23/25, Douglas C. Dildy and Tom
Cooper, pp. 43, 2016.
This
formation maximized the probability of detecting adversary aircraft across the
assigned mission area of combat air patrols. The potential coverage of two
pairs of F-22s employing a similar tactic would dwarf the original, but the
effectiveness of the tactic would be augmented considerably if at least two
aircraft per formation were equipped with sidelooking arrays providing vertical
and substantial additional horizontal coverage.
In the low observable “AWACS” role,
side panel equipped Raptors could provide a highly survivable situational
awareness capability for the joint force even within contested airspace. As of
fiscal year 2017 USAF budget documents, 72 F-22As will receive Link 16
capabilities in an unspecified waveform and all F-22s will receive IFTL Gateway
mode which will enable 5th to 4th generation
communications. Even after expending all internal weapons, F-22s will likely
remain close to the battlefield provided fuel is not a constraint given their
unique highly survivable battle management and command and control
capabilities:
After their
missiles were fired, the F-22’s active & passive sensor capabilities
functioned as the Raptor’s last weapon. Northern Edge 2006’s Raptors remained
in the fight, flying as stealthy forward air controllers and guiding their
colleagues to enemies sitting behind mountains and other ‘Blue Force’ AWACS
blind spots. When the AIM-120D AMRAAM missile enters wider service, F-22s will
also have the option of actively guiding missiles fired by other aircraft.[6]
Overall
assessment (1 – low, 5 – High):
Relative Utility: 3/5 – Intermediate
Technical Feasibility and Cost: 3/5
– Intermediate
Recommendation: Further technical and cost
analysis required utilizing classified information is likely required to make a
full assessment. The U.S. has yet to field a fighters equipped with sidelooking
arrays as of 2016. All existing USAF aircraft employing sidelooking arrays are
optimized at observation of ground targets such as JSTARS and Global Hawk.[7] Any contract would likely
be a sole source to Northrop Grumman since the system would have to be integrated
with the existing APG-77(V)1. Air Power Australia is among the few sources in
the public domain which states the base airframe has provisions for sidelooking
arrays, internal modifications since the initial design may have utilized any
existing growth margin. Furthermore, the full capabilities of the APG-77(V)1 may
be sufficient to provide acceptable C2 capabilities without further
investments. Determining the extent to which additional capabilities are needed
to monitor contested airspace likely merits its own in-depth technical study.
Incorporating
a different frequency band in the sidelooking arrays has the potential to
provide greater flexibility against intensive adversary jamming against the
X-band. However, the APG-77(V)1 is already highly resistant to jamming.
Furthermore, L-band arrays may not be able to provide similar target quality
track information required for weapons employment.
Helmet Mounted Display and Cueing
System
Image 4: Third generation HMD for the F-35. Image Credit: Rockwell Collins.
Arguably the most glaring current
deficiency of the F-22A is its lack of a helmet mounted display and cueing
system (HMDCS). HMDs are vital for within visual range engagements as they
enable the cueing of advanced off-boresight missiles such as the AIM-9X Block
I; off-boresight missiles paired with an HMD enable the pilot to look at an
adversary aircraft and gain IR missile lock on the target up to 90 degrees from
the launch point. Interception of the target even at extreme angles is possible
for modern IR guided missiles as a result of thrust vectoring and freedom from
biological g-limit constraints which dictate the maneuverability envelope
pilots can sustain. Without an HMD, Raptor pilots have had to rely upon their
traditional heads up display (HUD) for IR missile cueing and display of weapons
engagement zones (WEZ) which constraints IR targeting to the forward sector. At
the operational level, the lack of an HMD can be mitigated somewhat with the
lock-on-after-launch (LOAL) feature in the AIM-9X Block II as the missile will
loiter in close proximity to the launch point before being re-tasked by the
pilot to perform any aspect interception. However, the LOAL feature requires
integration of a two-way datalink which will not be completed until the
Increment 3.2b upgrades are completed.
Image 5: Off-boresight capability of the Python 4 IR guided missile. Image courtesy of Defense Industry Daily.
The USAF has tested the Thales
Scorpion HMDCS for integration with the F-22 in 2014, but the effort was
canceled as a result of sequestration.[8] FY 2017 USAF budget
documents indicate the USAF still plans to field a HMDCS system for the F-22 in
the near future:
The HMDCS
program will select, integrate, test and field a mature HMDCS to take full
advantage of advanced weapons such as the AIM-9X, and improved battlespace
situational awareness during day/night within-visual-range engagements. The
HMDCS will be integrated on all Block 30/35 Raptors.[9]
While
the integration of either the Joint Helmet Mounted Cueing System (JHMCS) or the
Scorpion HMDCS on the F-22 is likely, there are no official plans to develop
and integrate an equivalent to the Rockwell Collins third generation HMD for
the F-22. The main advantage of the F-35’s HMD over JHMCS or the Scorpion is
its integration with the distributed aperture system – a series of cameras
embedded in the F-35’s skin which provides real-time all-aspect tracking of
aircraft within a 15 nautical mile radius.[10] However, the F-22 does
not require an equivalent of the third generation HMD as it has no equivalent
of DAS. Furthermore, the single piece bubble canopy of the F-22 already affords
the pilot with excellent visibility when compared to the F-35’s cockpit without
DAS. An equivalent to the third generation HMD might be merited depending upon
a decision to fuse the sensor inputs of the AAR-56 Missile Launch Detector
(MLD) cameras into a cohesive system like DAS as well as the integration of the
advanced electro-optical targeting system (EOTS) which will be discussed in the
next article.
[1] Dan Katz, “Comparing F-22, F-35
Cost and Capability”, 2016. http://www.w54.biz/showthread.php?3375-Comparing-F-22-F-35-Cost-And-Capability
[3] Lolita C. Baldor, “F-22 Raptor
Ensures other War-Fighting Aircraft Survive Over Syria”, 2015. http://www.military.com/daily-news/2015/07/21/f22-raptor-ensures-other-war-fighting-aircraft-survive-syria.html
[4] Carlo Kopp, “Assessing the
Tikhomirov NIIP L-Band Active Electronically Steered Array”, 2009. http://www.ausairpower.net/APA-2009-06.html
[5] Carlo Kopp, “Lockheed-Martin /
Boeing F-22 Raptor”, 2012. http://www.ausairpower.net/APA-Raptor.html
[6] “Defense Industry Daily, “F-22
Raptor: Capabilities and Controversies”, last accessed September 2016. http://www.defenseindustrydaily.com/f-22-raptor-capabilities-and-controversies-019069/
[7] Defense Science Board, “Report of
the Defense Science Board Task Force on Future DoD Airborne High-Frequency
Radar Needs/Resources”, 2001. https://www.ciaonet.org/attachments/12186/uploads
[8] Dave Majumdar, “Air Force
Evaluating New Targeting Monocle for F-22 Raptor”, 2014. https://news.usni.org/2014/05/16/air-force-evaluating-new-targeting-monocle-f-22-raptor
[9] USAF Budget Documents FY 2017,
RTD&E Volume III Part I http://www.saffm.hq.af.mil/Portals/84/documents/FY17/AFD-160208-052.pdf?ver=2016-08-24-102137-043
pp. 420
[10] Dan Katz, “Comparing F-22, F-35
Cost and Capability”, 2016. http://www.w54.biz/showthread.php?3375-Comparing-F-22-F-35-Cost-And-Capability
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