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|  موضوع: رد: SU35 vs F35  الخميس 19 أغسطس 2010 - 13:22 | |
| - اقتباس :
Fighter Air Power Australia - Australia's Independent Defence Think Tank
Air Power Australia NOTAM
5th July, 2010
© 2010 C. L. Mills
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How will the intended 2,443 F-35s JSF impose air dominance for the USA and its Allies? That is the question to ask.
Search the Internet for material on the JSF and you will find terabyte
after terabyte of articles, pictures, Powerpoint presentations, PDFs,
tables and laudatory Blogs. And how much relates to how the JSF will
deliver this capability? You will find assertions and statement such as
‘six times better Relative Loss Exchange Ratio than legacy aircraft’
[1], or ‘The operational arguments focus on combat effectiveness
against top foreign fighter aircraft such as the Russian Su-27 and
MiG-29. Lockheed Martin and USAF analysts put the loss-exchange ratio
at 30-1 for the F-22, 3-1 for the F-35 and 1-1 or less for the F-15,
F/A-18 and F-16’[2].
And how will the F-35 JSF perform, not against truly obsolete legacy
aircraft like the Su-27SK and the MiG-29, but against modern fighters
like the Su-35S? We can answer these questions with a head-to-head
analysis of the two aircraft.
Air combat is a complex mix of art, science and engineering. Aircraft
performance, weapons performance, networked sensors and pilot skill all
contribute to the final Loss Exchange Ratio (LER). The only
simplification is that aircraft approach, engage in combat and the
survivors depart. This activity can be examined in a ‘kill-chain’ with
the following stages: ‘Detect-Identify-Engage-Disengage-Destroy’
(DIED2).
Here is a scenario. In the ‘Blue’ corner, we have a flight of four
F-35A JSFs, each armed with four AIM-120D Beyond Visual Range (BVR)
missiles and the 25 mm GD ATP GAU-22/A cannon. No additional weapons or
fuel are carried, because these would compromise the JSFs' “low
observability” to X-Band radar. In the ‘Red’ corner, we have a flight
of four Su-35S, each armed with four RVV-SD Active Radar Seeker BVR
Missiles, four RVV-SD Infra-Red (IR) Seeker BVR missiles, two RVV-MD
Within Visual Range (WVR) missiles, the 30mm GSh-301 cannon, KNIRTI
SAP-518 jammers on the wingtips and a 6,000 litre conformal tank
between the engines. Each aircraft has the full range of sensors and
countermeasures.
Here is a table to show how they compare:
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Figure 1: Diversity in missile
airframes and seekers. A Western pilot must be proficient in evasion
tactics for no less than six different families of BVR missile
airframes, and four different categories of missile seeker. The endgame
radiofrequency and optical countermeasures suites in a Western airframe
must be effective against seven different families of missile seeker,
including variants thereof. A pilot flying a Russian or Chinese
supplied fighter only needs tactics and technology to defeat the
AIM-120B/C/D AMRAAM. Not included is the R-27AE Alamo with a digital
variant of the RVV-SD active radar terminal seeker (Diagram © 2010 Dr
Carlo Kopp).
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Figure 2: A key problem for the
F-35 family of aircraft is that genuine X/S-band low observability is
only achieved in a relatively narrow angular sector around the nose of
the aircraft. This forces the aircraft to ‘point it's nose’ at the
highest threat, denying flexibility in prosecuting a missile shot, or
evading multiple threats. The absence of cheek and aft radar arrays
exacerbates the problem, and cannot be fixed given the weight, power
and cooling problems in the basic airframe design (Diagram © 2010 Dr
Carlo Kopp).
Whoa! The F-35A assessments are all marked in Red and Yellow – Inferior or Equivalent. Why is that?
Let’s look at each element of the ‘kill-chain’.
Detect:
Electronic Support Measures: Air
combat aircraft emit radiation from jet engines, radar, JTIS/MIDSs
terminal, radio transmissions. Specialised equipment in combat aircraft
knows the frequencies of these transmissions and has sensors to detect
them. Attempts are made to minimise emissions through a process of
‘Emission Control’ (EMCON) but these can only be partially successful.
Both the JSF and the Su-35S have a full range of these sensors, and are
assessed as being equally effective in ESM capability.
ESA Radar X-Band: This is the primary
sensor for jet fighters. The radar cross section of the F-35A is
substantially lower than that of the Su-35S especially in the front
sector, but the Sukhoi has sufficient power and a much larger antenna
to partially overcome that difference. Both types are ‘networked’ so in
a multi-ship engagement, the geometrical spread of the Su-35S flight in
part negates the lower observability of the JSF by illuminating the JSF
from angles where its low observability is weakest. Expect the F-35A to
often get the ‘first look’, but the Su-35S flight to detect the JSF
outside the range of the JSFs' BVR missiles. So where it matters, the
limited low observability of the JSF provides little advantage.
ESA Radar L-Band: The Su-35S will have
this lower-frequency radar in its wing leading edges. The JSF is
‘stealthed’ for X-Band, not for L-Band. While the antenna size of the
Su-35S L-Band radar limits its performance, there will be times when
the L-Band radar detects the JSF before the X-Band radar. The JSF does
not have an L-Band Radar and is assessed accordingly.
Infra-Red Search & Track: There is
a different approach to Infra-Red sensors. The JSF has a superb
Electro-Optical Distributed Aperture System (DAS) designed to cover the
sphere around the aircraft, but strongly optimised for air-to-ground
operations. The Su-35S has a large aperture OLS-35 IRST optimised to
scan for other aircraft at long range in its area of interest. DAS is a
‘staring array’ while the OLS-35 is a ‘scanning array’. The difference
in detection range is like the difference between a person searching
with a naked eye compared with another searching with a telescope. If
the telescope is pointed in the right direction, it will get first
detection. Add to that the factor that the JSF has the hottest engine
in the market, and the IRST of the Su-35S is assessed as a superior aid
to air combat.
Identification: Not much need to be
said here. The threat of fratricide in BVR air combat has led to the
development of identification systems that will reliable separate
friend from foe. Fratricide still happens though, especially in mixed,
close-in fights.
Engagement:
Mach on Entry: High Mach increases the
energy of BVR missiles, sending them further. The design top speed of
the Su-35S is 2.25, limited by canopy and radome heating, so it has
surplus power and the fuel to burn to sustain high Mach numbers. The
drag of the external stores is likely to reduce this to something below
Mach 2, but the missiles are cleared for launch at all speeds. The JSF
has yet to demonstrate a flight above Mach 1.05, but even if it reaches
its design speed of Mach 1.6, it is clearly inferior.
Altitude on Entry: Like Mach, a higher
altitude adds potential energy to BVR missiles, sending them further,
while an enemy’s missiles must ‘climb the hill,’ severely reducing
range. A second factor is that missiles fired from a higher altitude
have less drag, again increasing range. The JSF is optimised for Strike
missions flown at about 15-25,000 feet, while the Su-35S is optimised
for air combat missions at about 40,000 feet and above, with a combat
ceiling close to 60,000 feet. Points go to the Su-35S on operating
altitude.
Missile Range: The RVV-SD and the
AIM-120D have roughly equivalent ranges, but when the RVV-SD has a
high-Mach, high-altitude launch; it will outrange the AIM-120D. The
Su-35S is assessed at delivering a longer BVR engagement range. This
area of superiority will be increased once the RVV-AE-PD ramjet missile
becomes operational. In addition, the Su-35S can carry the very long
range R-37 and R-172 missiles, with ranges to 200 nautical miles.
Missile Seeker Diversity: The AIM-120D
currently has an active radar seeker, while the RVV-SD/R-77ME and the
R-77TE have active and infra-Red (IIR) seekers respectively. Mixed
sensor seekers complicate defences, for example, the F-35 may turn to
defeat an active seeker and expose a hot part of the aircraft to an IR
seeker. Russian doctrine is to ‘pair’ missiles with an active seeker
followed by a IR seeker, creating diversity in the fight and creating
‘kill’ opportunities. The Russian missiles also have the option of
passive anti-radiation seekers, designed to home on X-band radar. This
diversity in missile seeker sensors gives an advantage to the Su-35S.
Signature Exposure: This is a factor
that primarily affects the JSF, known to have a ‘Pacman’ radar
cross-section at X-Band, with a Low Observability ‘notch’ at the front.
As it manoeuvres, it can turn the notch away from an aircraft searching
sensor, and expose a higher radar cross-section to that search, or
expose a broadside or rear-side to another aircraft. The F-35 relying
on a ‘can’t see me, can’t kill me’ capability, has more to lose in a
spread, manoeuvring engagement than the Su-35S, which will generally be
detectable by the JSF for most of the engagement. This exposure can
occur, for example, when the JSF is guiding a missile and turns away to
reduce the closure rate, thereby exposing both the aircraft and an
incoming missile to longer range detection, or detection from a widely
spaced wingman. As the JSF is reliant on signature reduction for
survival, it has more to lose if its signature increases, so is
assessed as more vulnerable in the dynamics of a multi-ship, networked,
turning engagement where signature management is very difficult.
Endgame Electronic Countermeasures (ECM):
The ‘modus operandi’ of stealth aircraft is not to radiate, or return
radiation, which is the way ECM countermeasures work. Su-35S has ECM,
JSF does not, except for intended AESA Radar jamming modes across a
limited forward cone of about 120 degrees. ECM based on Digital Radio
Frequency Memory (DRFM) can be very effective, especially against
missiles with limited processing power and time to resolve targets. The
Su-35S also has several ECM modes. The JSF is assessed as inferior,
because it does not employ ECM to defeat attack.
Decoys Towed / Fired: The Su-35S has
the option of deploying towed decoys to lure a closing missile away
from the body of the aircraft. The JSF approach is different, with
small ‘Gen-X’ active decoys being fired as a missile closes. These
measures are assessed as being approximately equivalent, with the towed
decoys which are at co-speed to the target likely to present the more
effective countermeasure.
Flares and Chaff: These are outmoded
countermeasures, but still add to the difficulty of guiding a missile
to close proximity of an airframe. The GSh-301 is claimed to have
rounds that fire chaff forward of the aircraft, so chaff-discrimination
processing in a closing missile might be deceived. Nonetheless, the
countermeasures are assessed as equivalent.
Mach for a Tail-Chase / Fuel Reserves for Afterburner:
At some time in a fight, an aircraft has to depart, for example when
‘Winchester’ or out of ammunition, or ‘Bingo’ or down to just enough
fuel to get home. Then the fight becomes a tail-chase. The Su-35S with
its higher Mach can close on a JSF, the reverse is not the case. The
ability of the Su-35S to carry large fuel loads, and the prodigious
consumption of the JSF F135 engine in maximum afterburner exacerbates
this perilous situation for the JSF. The advantage is with the Su-35S
in these aspects of engaging in a fight when the JSF is attempting to
disengage.
Disengagement: This is one of the
under-assessed areas of future air combat. When missiles of roughly
equivalent range are fired, they travel for over 100 seconds to the
target. This transit time provides an opportunity for countermeasures
to defeat the attack. Missile motor launch-flares are intensive and
difficult to hide from Infra-Red sensors, so in many engagements, there
will be early warning of an incoming missile. Active seekers ‘light-up’
at about 10 nautical miles from the target, still providing valuable
warning time. Here is a range of disengagement measures:
Airframe Agility: Once warned of a launch, the defending aircraft can
sometimes defeat the attack by rapidly turning away to force the
missile into a tail-chase.
Antenna Coverage: AESA radars like the
JSF APG-81 working from a fixed back-plate cover a cone of about 120
degrees. The Su-35S has an ESA radar working from a gimballed
‘swash-plate’ that covers about 240 degrees around the nose, and there
is a second radar in the ‘stinger’ albeit with less capability, to
cover the remainder of the sphere. If the Su-35S and the JSF fire a BVR
missile at the same time and at maximum range, the Su-35S can turn away
to about 120 degrees off the line joining the two aircraft, while the
JSF is constrained to about 60 degrees. This runs the JSF into the
Su-35S’s missile, while the Su-35S is running away from the JSF’s
missile. The result could be an RVV-SD hit and an AIM-120 miss. Points
to the Su-35S on this aspect.
Mach on Egress / Fuel Reserves for Afterburner:
This is an extension of the antenna coverage capability, as the Su-35S
can accelerate away from the incoming missile, forcing it to
drop-short. The JSF does not have this performance and is assessed as
inferior.
Destroy:
Missile Seeker Diversity: At terminal
phases of an engagement, there may be several missiles in the vicinity,
with aircraft manoeuvring to defeat the attack. An incoming missile
with an IR seeker may be presented with the ‘rear end’ of a JSF and
track for a kill. This opportunity is not available to the JSF
attacking the Su-35S, as its limited missile carriage does not include
BVR missiles with IR seekers.
Missile Agility: This is the ‘flip
side’ of aircraft agility. The R-77 has the famous ‘potato masher’
lattice-tail control surfaces, that while increasing drag over
conventional surfaces, also give greater terminal manoeuvring
capability. So, the Su-35S BVR weapons can out-turn the F-35’s weapons.
Warhead Lethality: This is a mix of
warhead destructive power and the vulnerability of the target airframe.
The AIM-120D has an 18 Kg, fragmentation warhead, and the Su-35S widely
spaced armoured engines, armoured sections of the airframe and
redundancy of system. The R-77 missiles have 30 kg expanding-rod
warheads to destroy the single-engine JSF, from which critical systems
like fire suppression have been removed to reduce weight and cost. The
Su-35S is assessed as superior.
WVR Missiles: This is as simple as
‘the Su-35S carries WVR missiles, the JSF does not’ (in this example).
The JSF can carry WVR missiles, but they are an external mount,
impairing radar signatures.
Guns Lethality: Bigger is better. 30
mm rounds have more explosive power than 25 mm rounds. Again, the
airframe vulnerability is an issue and a single 30 mm hit to the JSF’s
single engine could bring it down.
At the end of the kill-chain, it seems, prima facie, that the Su-35S
has all the ‘right stuff’ for air combat, while the F-35 JSF does not.
This should come as no surprise, because the design brief for the JSF
was that the F-22A would ‘sanitise’ airspace and deliver air dominance,
making it safe for the Joint STRIKE Fighter to deliver follow-up strike
capabilities.
Now that the F-22A Raptor program is being terminated with insufficient
aircraft to deliver air dominance, this role is now being assigned to
the F-35 JSF.
Given the intent of the OSD to employ the F-35 Joint Strike fighter as
an air dominance fighter, the fundamental and unanswered question is:
HOW
How? The Deadly Question for the F-35 Joint Strike Fighter
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عدل سابقا من قبل الدرع المصرى في الثلاثاء 24 أغسطس 2010 - 12:05 عدل 1 مرات |
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