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Archive for December 14th, 2013

Fighter aircraft generations issue

Posted by picard578 on December 14, 2013

Introduction

Jet fighters are grouped into generations based on their design characteristics. But there are problems with that approach.

One would logically assume that higher the generation number, better is the aircraft when it comes to air-to-air combat. But examination of history shows that this is not true.

First generation fighters are Me-262, F-86, MiG-15 and MiG-17. Second generation fighters are Dassault Mirage III, Saab Draken, F-104, F-105 and MiG-21. Third generation fighters are F-4, F-5, MiG-23, MiG-25 and Saab Viggen. Fourth generation fighters are Dassault Rafale, MiG-31, MiG-29, Su-27, Saab Gripen, Eurofighter Typhoon, F-15 and F-16. Only active fifth generation fighter is the F-22 Raptor, whereas J-20 and PAK FA are in development.

First, second and third generation fighters have all seen combat in the Vietnam war, which can thus serve as a perfect case study of wether higher generation number automatically means more capable fighter aircraft.

History

In Vietnam war, NVAF lost 131 fighters (NVAF claim) or 210 fighters (US claim) of which 110 MiG-17, 10 MiG-19 and 90 MiG-21. If NVAF figure is correct, it might indicate even worse performance for radar-guided missiles than thought. According to US claims, MiG-21 achieved 85 kills and 95 losses. F-4 allegedly achieved 151 kill while suffering 41 loss to aircraft. As opponent’s losses are usually overreported, F-4 may have achieved “only” 94 kills, possibly even less. This 2:1 kill/loss ratio is consistent with what was reported in April 1982 study “Comparing the effectiveness of air-to-air fighters” by Pierre Sprey. Russian records indicate 103 F-4s shot down by MiG-21 in exchange for 53 lost. Considering that pilots tend to overreport successes due to confusion of combat – mistaking damaged enemy aircraft or one going low to avoid attack for a shootdown, for example – actual exchange ratio was likely near parity (41 F-4 loss and 53 MiG-21 losses). In summer of 1972, air-to-air combat resulted in loss of 12 MiG-21s, 4 MiG-17/19 and 11 F-4s, for a kill/loss ratio of 1,4:1 in favor of Phantom. It should be noted that this was late in the war when F-4s would have better kill/loss ratio than early in the war due to improved pilot training. However, many MiG sorties were bomber intercepts, and MiGs were ordered to ignore escorts and focus on bombers.

It is certain however that F-4 had a negative kill/loss ratio before US pilots started being trained for dogfighting (possibly as much as 3:1 advantage for MiGs); after that, advantage in training over often undertrained (though still competent) NVAF pilots helped level the field. But speaking purely from flight performance viewpoint, Boyd has shown that the F-4 could only fight MiG-21 at low altitude and high speed, and even F-4 pilots were critical of its maneuverability. MiG-21 itself was not a great dogfighter, having difficult handling, and NVAF pilots preferred MiG-17 which did very well against F-4s (and F-105s, though as these were usually used as bombers it is not surprising).

In 1967 and 1973 Israeli-Arab wars, visual-range Mirage III fighters achieved 20:1 kill/loss ratio against MiG-21s. This was primarly due to pilot quality, however Israeli pilots considered Mirage III a far better fighter aircraft than US F-4, which they referred to as “B-4”.

in the 1971 Indo-Pakistani war, Pakistani visual-range-only F-86s achieved better than 6:1 exchange ratio against Indian supersonic MiG-21s, Su-7s and Hawker Hunters, in good part due to its small visual signature and good cockpit visibility. Only Indian fighter that managed to match the F-86 was also subsonic Folland Gnat, which had advantage of being the smallest fighter in the war. In earlier 1965 war, Gnat also had advantage over F-86: even Pakistani sources credit it with 3 F-86 kills for 2 losses to the F-86, while Indian sources credit it with 7 F-86 kills.

And as I have pointed out in another article: “While comparing total kill/loss ratios, expensive fighters may seem to be better off than less expensive ones. However, this is not due to fighters themselves but because only nations that can afford expense of quality training can also afford expensive fighters. Thus advantage given to fighter by the pilot is unjustly attributed to fighter’s own qualities.”

Comparision of modern fighters

F-35 is often called a “fifth generation fighter”. This is wrong on multiple levels: first, it implies that it is superior in air-to-air combat to “fourth generation” fighters, and second, it implies that valid definition of what makes a “fifth generation” fighter even exists.

Fifth generation is allegedly a term that implies combination of stealth, high maneuverability, advanced avionics, networked data fusion from sensors and avionics, and ability to assume multiple roles. But as Canada’s auditor general noted on page 23, there is no objective definition of the term, or indeed the entire generations division.

Even if definition of fifth generation outlined in the second paragraph of this section is accepted, some aircraft that are commonly defined as fifth generation do not fulfill requirements for definition, and some fourth generation fighters better fit that description than most self-proclaimed fifth generation ones.

Stealth itself is a far more complex issue than what Lockheed Martin propaganda states, and can be divided into visual, EM, infrared and acoustic stealth. Visually, Gripen is the smallest Western fighter, followed by F-16, Rafale, Typhoon, F-18, F-35, F-15 and finally F-22. In EM spectrum, F-22 and F-35 are the only fighters which are stealthy to enemy radars in entire 360-degree horizontal circle; however, Gripen, Rafale and F-16, while not relying on radar LO as their main design point, also have a design which gives them reduced RCS from all aspects. But this is only half an issue; fighter which uses its radar to detect the opponent cannot be called stealthy, and only Rafale, Typhoon and F-35 have IRST. Since F-35s IRST is optimized for ground attack, only Rafale and Typhoon actually have an IR sensor meant for air-to-air combat. On the other hand, Rafale and F-22 are the only fighters which can use opponent’s emissions to attack him, though this capability does not matter much if enemy is not emitting radio signals (radar, IFF or datalinks). Radar signature of each fighter is distictive, meaning that Rafale and F-22 can identify the enemy at BVR just through his radar emissions. IR stealth itself is a toss-up: Gripen C is very small and has low IR signature but cannot supercruise, increasing its IR signature considerably when supersonic. F-16 is larger, with stronger engine and also lacks ability to supercruise. Rafale C is even larger; its engines however have IR signature reduction measures and it is capable of supercruise, meaning that its IR signature at supersonic speeds may be lower than F-16s or Gripen’s. Typhoon can also supercruise, but is even larger than Rafale and has no IR signature reduction measures. F-35 and F-15 have no IR signature reduction measures, are incapable of supercruise and are larger than all fighters mentioned before; F-18 is not much larger than Typhoon or Rafale, but is also incapable of supercruise. F-22 has IR signature reduction measures and is supercruise-capable, but its mammoth size limits utility of these measures in reducing its IR signature. As a result, while F-22 is most stealthy in respect to active X-band radars, and Gripen has lower visual signature, Rafale is overall most stealthy fighter of those compared.

All fighters mentioned, except for F-18E, are also far more maneuverable than the F-35. F-35 itself has a fairly classic aerodynamic configuration, which means that majority of lift comes from wings. But F-35As wing loading is high (428 kg/m2 at combat weight), clearly insufficient to match that of Western air superiority fighter (Rafale C: 276 kg/m2; F-15C: 278 kg/m2; Gripen C: 293 kg/m2; F-22: 314 kg/m2; F-16C: 392 kg/m2). Its thrust-to-weight and thrust-to-drag ratios are also inferior to those of most aircraft mentioned, with only Gripen having lower thrust-to-weight ratio but better thrust-to-drag ratio. Neither does the F-35 have thrust vectoring or close-coupled canards to provide it with improved maneuverability at supersonic speeds and post-stall maneuvering and recovery capability. Rafale, with its high g capability, low wing loading (lowest of fighters compared), excellent thrust-to-drag ratio, adequate thrust-to-weight ratio, excellent responsitivity to control inputs and unmatched roll onset rate again wins.

Advanced avionics are present on most modern fighters. F-22, F-35 and Rafale have AESA radar, with Typhoon being slated to get one. F-35, Rafale and Typhoon also have IRST. F-35s DAS will, if everything goes fine, provide pilot with 360 degree spherical view of his surroundings, but Rafale also has most of that capability (two more IR sensors are required for a spherical view) and F-35s DAS does not work yet. No other fighter mentioned has that capability. Integrated countermeasures are already operational on Rafale (SPECTRA) and Typhoon (DASS), and are planned for Gripen NG.

Networked data fusion is present on F-22, F-35, Dassault Rafale and Eurofighter Typhoon, as well as proposed Gripen E. Both Rafale and Typhoon have demonstrated the capability turing Libya campaign. Networking capabilities themselves are already present in a long time in form of NATO Link 16 datalink.

Multirole capability is present on more fighters than not. In fact, only single-role fighters are F-22, F-15A, F-15C and A-10, though A-10 can actually perform multiple roles if required. Rafale is replacement for 7 different types of aircraft in French service; Typhoon is also improving multirole capability, while Gripen was multirole from beginning. Rafale however offers best multirole capability.

Other F-35 “innovations” – such as integrated countermeasures – are operational on Dassault Rafale (SPECTRA) and Eurofighter Typhoon (DASS).

In short, if there is a true fifth generation fighter, it is Dassault Rafale, not the F-35 or even the F-22. But entire “generations” label is misleading. First operational US fighter jet was F-80, followed by F-86, F-100, F-104, F-4, F-15 and F-22, each being (allegedly) a generational improvement over its predecessor. If this division is taken, then F-22 is 7th generation fighter, Rafale is 8th generation, and F-35 is a true 5th generation fighter, being as “capable” in air-to-air as F-4 (some of which are still flown by Luftwaffe).

Bottom line: “fifth generation” label is a myth.

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