Defense Issues

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Posts Tagged ‘maintenance downtime’

Fighter aircraft engine comparision

Posted by Picard578 on December 6, 2014

Introduction

This article will compare several engines used in modern fighter aircraft: EJ200 (Typhoon), M88 (Rafale B/C/M), RM-12 (Gripen A/B/C/D), F-135 (F-35A/B/C), F-119 (F-22A), F404-GE-402 (F-18C/D), F-414-400 (F-18E/F, Gripen E/F), AL-31F (Su-27, Su-30, J-11). Read the rest of this entry »

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USAF force proposal

Posted by Picard578 on October 30, 2012

Current USAF plan is to keep 187 F-22s, 254 F-15 C and 221 F-15E in service, replacing 716 A-10s and 2 154 F-16s with 1 763 F-35As.

Problem with that is multifold; first, large unit and maintenance costs. Per-unit cost of 304 million USD per aircraft, 197 million USD flyaway, and operating cost that will likely be around 48 800 USD per hour of flight,1 763 F-35s will cost 535,952 billion USD to procure. Operating costs for that fleet will be 86 034 400 USD per hour of flight.

187 F-22s in service have so far cost 79,475 billion USD to procure and upgrade (including fixes) and have total operating cost of 11 407 000 USD per hour – 61 000 USD per hour per aircraft. This means that combined F-22/F-35 fleet will cost 97 441 400 USD per hour of flight.

To compare with these costs, “ancient” F-16C that are now being replaced by F-35 have operating cost of 7 000 USD per hour of flight. F-15C costs 30 000 USD per hour of flight, F-15E costs 28 000 USD per hour of flight, A-10 costs 3 000 USD per hour of flight. Eurocanards cost 18 000 USD per hour of flight for Typhoon, 16 500 USD per hour of flight for Rafale and 4 700 USD per hour of flight for Gripen.

Maintenance downtime is 6,2 hours per hour of flight for A-10, 19 hours per hour of flight for F-16, 10 hours per hour of flight for Gripen, 9 hours of maintenance for Typhoon, 8 hours of maintenance per hour of flight for Rafale, 20 hours per hour of flight for F-15, 45 hours per hour of flight for F-22. (I wasn’t able to confirm Eurocanards’ maintenance downtime figures, however).

Thus, by using maintenance and flyaway costs, and ignoring R&D costs that have been sunk, we can break down costs of desired USAF fleet as:

187 F-22A: 46 750 000 000 USD price, 11 407 000 USD per hour of flight
254 F-15C: 10 820 400 000 USD price, 7 620 000 USD per hour of flight
221 F-15E: 9 757 592 000 USD price, 6 188 000 USD per hour of flight
1 763 F-35A: 347 311 000 000 USD price, 86 034 400 USD per hour of flight

For total of 414 638 992 000 USD, and costing 111 249 400 USD per hour of flight.

By using Desert Storm and current sortie rates (1 sortie / day for F-15, 1,2 for F-16, 0,3 for F-22, 1,4 for A-10), we see that F-22s will be able to fly 60 combat sorties per day, and F-15Es will be able to fly 221 combat sortie per day. F-15Cs will be able to fly 254 sorties per day. While I don’t know F-35’s maintenance downtime, it can be estimated that it will be able to fly 500 – 800 sorties per day. Thus above force will be able to sustain 2650 sorties per day.

Two fighters, F-22 and F-15C together cost 57 570 400 000 USD, and 19 027 000 USD per hour of flight. Strike-oriented F-15E and F-35A will together cost 357 068 592 000 USD and 92 222 400 USD per hour of flight.

Replacing F-22 and F-15C with F-15As gives 1 351 aircraft, costing 40 530 000 USD per hour of flight, and able to support around 1 400 sorties per day. Replacing F-15E and F-35A with F-16C gives 5 951 aircraft, costing 41 657 000 USD per hour of flight, and capable of supporting around 7 140 sorties per day. Better option would be 5 000 F-16C and 3 800 A-10, costing 357 billion USD to procure and 34 900 000 USD to maintain per hour of flight. 5 000 F-16C can support 6 000 sorties per day, and 3 800 A-10 can support 5 320 sorties per day.

Replacing F-22 and F-15C with Eurofighter Typhoon gives 480 aircraft, costing 8 640 000 USD per hour of flight, and able to support 1 152 sorties per day. Replacing F-15E and F-35A with Saab Gripen gives 5 951 aircraft, costing 27 969 700 USD per hour of flight, and able to support 13 092 sorties per day.

To sum up:

F-22A + F-15C + F-15E + F-35A = 2 425 aircraft and 2 650 sorties per day. Total procurement cost 415 billion USD, total maintenance cost per hour of flight 111 million USD.

F-15A + F-16C = 7 302 aircraft and 8 540 sorties per day. Total procurement cost 415 billion USD, total maintenance cost per hour of flight 82 million USD.

F-15A + F-16C + A-10: 9 851 aircraft and 12 720 sorties per day (7 400 sorties by air superiority-capable aircraft). Total procurement cost 415 billion USD, total maintenance cost per hour of flight 75 430 000 USD.

EF2000 + JAS-39C = 6 431 aircraft and 14 244 sorties per day. Total procurement cost 415 billion USD, total maintenance cost per hour of flight 37 million USD.

Thus either F-15A + F-16C or EF-2000 + JAS-39C option would be superior to an all-stealth option USAF is promoting in both cost and cost effectiveness area. Not only is large number of sorties per day required for establishing air superiority, it is also required for pilot training, which is one of most important things any air force must do; simulators are just that: simulators, and while they can simulate live training, they cannot replace it.

Meanwhile, stealth is overrated: during Kosovo War, stealth F-117s suffered greater number of casualties (1 aircraft shot down, 1 damaged and mission-killed but returned to base, never to fly again) than non-stealth F-16s (1 F-16 shot down), despite being “stealth”, and despite flying lower number of sorties – 1 300 sorties compared to 4 500 sorties for F-16. Final nail on the “stealth is required to cope with SAM’s” coffin is SAM effectiveness rate through war: 0,36 %. Even air-to-air BVR missiles have Pk in single-digit percentages against capable opponent – after lock-on is achieved, and assuming anyone even turns radar on. IRST + RWR – equipped aircraft can stay completely passive, leveling the playing field by forcing stealth aircraft to rely on IR sensors – where smaller, non-VLO aircraft will have advantage – or to radiate and give up its position; and air-to-air anti-radiation missiles, or BVR IR missiles coupled with cueing by aircraft’s defensive suite, can force everyone to rely on passive sensors only.

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F-22 fact spinning on USAF website

Posted by Picard578 on October 28, 2012

I was browsing http://www.af.mil, 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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