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Archive for October 28th, 2012

F-22 fact spinning on USAF website

Posted by picard578 on October 28, 2012

I was browsing, when I have found this page. While most, possibly all, of claims there have been addressed in my F-22 Analysis, I am aware that it is very long read, and as such I will examine claims here.

First claim is that “The F-22 possesses a sophisticated sensor suite allowing the pilot to track, identify, shoot and kill air-to-air threats before being detected.”. Problem with that claim is that F-22 has no sensor capable of tracking and identifying target without requiring either F-22 or enemy aircraft to actively use its radar. Thus, F-22 must either rely on (jammable) uplink from another unit or on enemies being willing to give it first strike possibility by radiating themselves. However, IRST-equipped aircraft can detect subsonic fighter aircraft from large distance, without being required to radiate themselves – Su-35 can do it from 50 kilometers head-on, and Eurofighter Typhoon from 90 kilometers, also head-on. From rear, Su-35 can detect subsonic fighters from 90 kilometers, which means that Typhoon can do the same thing from over 150 kilometers.

While F-22s radar can detect 1m2 target (which is approximately same as Typhoon’s frontal RCS when in air-to-air configuration) from 200 – 240 kilometers, jammers can reduce range required for a lock-on to be achieved to less than a third of range in non-jammed environment. That can be confirmed by recent exercises, where F-22 was unable to lock on clean-configured Typhoon from front until latter was 20 miles (32 kilometers) away; as Typhoon has frontal RCS (when clean) between 0,25 and 0,75 m2, it means that F-22’s radar range has been reduced by jammers to approximately 14,4 – 22,7 % of expected range. Thus, F-22 cannot be expected to lock on combat-configured Typhoon from range larger than 45 – 54 kilometers from front. Both ranges are well inside detection range of PIRATE IRST. With Su-35, situation is somewhat better, due to its larger RCS and lower-capability IRST; however, reduction of radar range by jammer, which means that F-22 may not be able to even launch all BVR missiles (and even if it does, 6 BVR missiles combined have Pk of 36 – 48 % against capable opponent) means that far more enemy aircraft than is assumed will be able to get to visual range with F-22.

While F-22 is a capable dogfighter for its size and weight, its low production run and high maintenance downtime mean that it will likely find itself outnumbered in any war against China – which is a primary justification for continuing production. For comparasion, while Su-35 has flyaway cost of 65 million USD at most, F-22 has flyaway cost of 250 million USD, and maintenance downtime of 45 hours per hour of flight. While I was unable to find any figures for Su-35s maintenance downtime, it most likely isn’t worse than 30 hours per hour of flight as required by USAF’s ancient F-15s. Thus, F-22 will find itself outnumbered 5:1 in best case, whereas Typhoons, with flyaway cost of 120 million USD and maintenance downtime of 10-15 hours per flight hour, might even be able to slightly outnumber Su-35s.

What is worse, Russians have air-to-air anti-radiation missile (R-27P), and are very willing to sell it over the world. As internal USAF exercises have shown during the Cold War, several aircraft equipped with anti-radiation missiles can force everyone to shut down radars. That, in turn, will force aircraft to return to visual-range dogfight, with IRST-equipped aircraft having very large advantage in situational awareness – even larger than usual.

Second claim that needs examining is the value of stealth. While I have already discussed value of stealth in air-to-air scenario, I have not addressed scenario with surface-to-air threats – mostly SAMs.

While it is true that stealth aircraft have increased survivability compared to legacy aircraft when confronted by X-band radars, it is not so with lower-frequency, long-wavelength radars. Namely, aircraft RCS depends on size and shape of aircraft, its position relative to radar waves as well as wavelength radar in question is using. Stealth aircraft are designed to scatter radar waves away from (monostatic) X-band radar, with stealth coating absorbing minor part of radar signal. However, that only works when wavelength is far shorter than dimensions of the shaping features of the aircraft. Against VHF radars, with their 1-2 meters long waves, fighter aircraft such as F-22 and F-35 will see majority of their shaping features fall into either resonance or Raleigh scattering region. In these regions, shape of feature in question becomes irrelevant, and skin becomes electrically charged by radar waves, increasing RCS even further. Against such radars, stealth aircraft are forced to use same tactics as legacy aircraft against any type of radar, making stealth irrelevant and even harmful.

Third claim is that F-22’s engines produce more thrust than any current fighter engine. While it is true, F-22 is also heaviest fighter aircraft in existence, and these powerful engines give it thrust-to-weight ratio of 1,09 at loaded weight and 1,28 with 50% fuel, 2 Sidewinders and 4 AMRAAM. Later value is same as Eurofighter Typhoon, while former is inferior to Typhoon, which has TWR of 1,14 at loaded weight. Rafale has thrust to weight ratio of 1,1 at loaded weight, and 1,23 with 2 WVR, 6 BVR missiles (all MICA) and 50% fuel.

Fourth claim is that F-22 can outmaneuver all current and projected aircraft. It cannot; thrust vectoring is only useful as help with maneuvering at speeds below 150 knots; above 150 knots aircraft ends up with drifting motion – lower aircraft has TVC, upper doesn’t – which increases drag for no decrease in turn diameter. At the onset of the turn, aircraft looses lift and sinks in mid-air, with nose rotating up. Suffice to say, both of these effects are very dangerous in visual-range dogfight, especially in era of high off-bore missiles.

Fifth claim is that “The combination of stealth, integrated avionics and supercruise drastically shrinks surface-to-air missile engagement envelopes and minimizes enemy capabilities to track and engage the F-22 .” Stealth has already been addressed  as have sensors; supercruise is of interest here. While non-afterburner supercruise is useful, as it reduces fuel expenditure and heat signature of exhaust plume, it is not a game breaker. F-22 has low fuel fraction, is heavy and with large amount of drag, limiting duration of supercruise. Moreover, aircraft supercruising at Mach 1,7 can be tracked from 10% longer range than subsonic one, which means that Su-35 will detect it from 55, and Typhoon from 100 kilometers, head on. Reduction of engagement envelope can be achieved by increasing speed, supercruise or not; however, supercruise does reduce fuel expenditure, although such reduction is not very large.

Next is the claim that F-22 will have “better reliability and maintainability than any other fighter aircraft in history”. With F-22s maintenance costs and downtime being as they are (maintenance downtime of 45 hours per hour of flight, maintenance cost of 61 000 USD per hour of flight, and availability rate of 55,5%), claim is certainly false. Indeed, while Eurofighter Typhoon is a very complex aircraft, comparing it with F-22 produces shaming numbers: maintenance downtime of 10-15 hours per hour of flight, cost of 18 000 USD per hour of flight, and availability rate from 50% for Luftwaffe to 88% for RAF during Operation Elamy, RAF participation in Libya. Dassault Rafale costs 16 500 USD per hour of flight; unfortunately, I do not have figures for either maintenance downtime or availability rates.

Last is the characteristics table. While most of it seems correct – I won’t check it now – unit price is not. When debate has been held about ending F-22 production at 187 aircraft, proposal was to buy seven more F-22s for total price of 1,75 billion USD. Since it R&D expenses have already been paid, and production line was still active, sum shows an actual F-22 flyaway cost of 250 million USD per aircraft.


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