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Posts Tagged ‘stealth’

Air combat and stealth

Posted by Picard578 on March 11, 2017

Introduction

For a long time, visual detection was the only type of detection possible. But in World War II, two significant advances appeared: radar, as well as radar- and IR- -guided missiles. Until 1970s, these were defeated through jamming and decoys. Early German attempts at building LO aircraft – Ho-229 – never got anywhere, albeit their RAM paint utilization at snorkels and aircraft was noted. In United States, first attempt at reducing the radar signature of aircraft was on U-2, by utilizing RAM paint, but it was not very successful. First actual stealth aircraft appeared in early 1960s – SR-71 Blackbird, which utilized shaping such as canted surfaces to reduce radar signature. In 1970s a second generation of stealth aircraft appeared with B-1A, and also began a programme of development of VLO aircraft. Result of that was diamond-shaped F-117, to soon be followed by B-2. All these aircraft successfully performed against enemy air defenses, but in the case of B-1A and later aircraft, their performance against air defenses was similar or identical to performance of conventional aircraft they were deployed alongside. Fourth generation of stealth aircraft are F-22, F-35, PAK FA, J-20 and J-31. While still stealth aircraft, they sacrifice stealth characteristics for the sake of better flight characteristics, allowing them to match conventional fighters in terms of maneuverability. However, their stealth requirements make them larger and heavier than comparable conventional aircraft, thus sacrificing kinetic performance for the sake of stealth.^1 Read the rest of this entry »

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Defining stealth

Posted by Picard578 on March 1, 2017

Introduction

Word “stealth” has lately become a catchword used to define the weapon – mostly aircraft – as “superior”, with little or no thought as to what the term actually means. Stealth fighters, stealth bombers, stealth ships… even stealth tanks, the craze is in full swing. But how much do these weapons deserve the label? What is stealth? Is merely having low radar cross section enough – as commonly held – to define the weapon as “stealth”? Is USAF stuck on denial that no military advantage lasts forever, or even on denial that it never understood the true meaning of stealth? Every successful use of stealth aircraft had seen them acting as a support of, and being supported by, an array of nonstealthy aircraft – AWACS, standoff jammers etc. Yet USAF is now aiming for an all-stealth tactical fighter force, even though it will make the force less flexible and arguably less capable as well. How stealthy these aircraft really are, and what are their vulnerabilities? Read the rest of this entry »

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Stealth – evolution of justification

Posted by Picard578 on August 1, 2015

Radar stealth does not work very well against airborne threats for three very simple reasons. First, visual identification is necessary before engagement, which requires fighters to close in to either eyeball or optical sensor range. This means that larger fighter is at disadvantage, and stealth fighters are always larger than comparable non-stealth fighters. Second, pilots will always try to approach enemy or unknow fighter from the rear to maximize time avaliable for identification and minimize possibility of being detected. This requires higher cruise speed than the target, but also that fighter remains silent during the entire intercept. While fighter performing intercept might benefit from greater situational awareness, using onboard radar warns everyone in vicinity and significantly reduces a possibility of successful attack by either intercepting fighter itself or by any friendly fighters – even those not using the radar. Third, stealth assumes that aircraft will use radars but nobody will have competent RWRs. Read the rest of this entry »

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Aircraft signature reduction measures

Posted by Picard578 on March 9, 2014

Rafale

rafale1 Read the rest of this entry »

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How stealthy is the F-35

Posted by Picard578 on October 19, 2013

Introduction

F-35 is the newest Western flying piano. Apparently US have already forgotten all the lessons of World War II and Vietnam war, where such impressive-on-paper-but-sluggish fighters ended up on mercy of far more nimble fighters and were thus relegated to ground attack roles. In fact, F-35 was designed as a ground attack aircraft, only to be pressed into service as “multirole” fighter after F-22 killed itself with cost overruns (how decision-makers figured that three-service aircraft would be better than a single-role single-service aircraft in that respect is beyond me, especialy after Aardvark disaster; only thing F-35 has for it is that it is lighter than the F-22, allowing for limited cost savings for some variants when compared to the F-22). And despite what some might think, F-16 was the first – and last – US fighter designed with maneuverability in mind; both P-51 and F-86 ended up maneuverable by pure luck, as they had to have low wing loading to function as high altitude bomber interceptors, and P-51 also got equipped with excellent British Merlin engine. F-22 is similarly a high-altitude bomber interceptor, and while it does have good maneuverability, it is not designed for it, as evidenced by the fact that it needs thrust vectoring to achieve angle of attack required for maximum lift; comparably low wing loading (about same as F-15C) and high thrust-to-weight ratios are features required by its role as a high-altitude fighter.

Due to this maneuverability shortcoming, F-35 has to rely on surprise attacks against the enemy: detect before being detected. That is, after all, entire purpose of stealth. But how stealthy is the F-35? Is it stealthy at all? What must be kept in mind is that stealth is not limited to just radar. For this reason, I will take a look at F-35s stealth in multiple areas.

F-35s stealth Read the rest of this entry »

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Value of stealth aircraft

Posted by Picard578 on March 30, 2013

Introduction

Unlike US Navy and every other air force across the world, USAF has decided to transit to an all-stealth air force.

But due to the Moore’s law, processing power doubles every 18 months – which means not only improvements in sensors that are already very capable of detecting stealth aircraft, but also that, as time passes, stealth aircraft is ever less capable against systems it was designed to counter – namely, active radars.

Air-to-air combat

Stealth vs radar

Stealth relies on processing gain advantage over radar, by reducing return below treshold of what can be detected by radar itself. However, due to the Moore’s law, radars are becoming ever more capable. Further, stealth fighters are designed with minimum nose-on RCS, which means that they are easier to detect by aircraft flying in wall formation. At the same time, jammers benefit from Moore’s law too, which enables fighter-based jammers to rapidly close the effectiveness gap with stealth, or even surpass it.

This purely theoretical thought exercise is not likely to be very relevant, however, as radar – being an active sensor – automatically gives position of aircraft using it away far before it can detect opposing aircraft, meaning that pilots will start shutting it down in combat as soon as losses due to its use start to mount due to radars’ use giving very important advantage of surprise to the opponent. Against both enemy aircraft and SAMs, dedicated jamming aircraft – ranging in size from converted medium-weight fighters to converted heavy bombers – are avaliable, and far more effective since they also protect other aircraft.

Stealth vs IRST

Most discussions about value of IRST against stealth focus on airframe being heated due to air friction. This, however, is wrong for a very simple reason: any time a gas is compressed, it heats. And compression of gasses in front of moving object is a normal, unavoidable occurence – only difference is scale of compression, which depends on object’s speed.

While aircraft do heat up less in rarer atmosphere, less atmosphere also means that more IR radiation – especially of longwave variety – reaches the infrared sensor. Further, at high altitudes – where stealth aircraft are required to operate – temperatures range from -30 to -50 degrees Celzius. At the same time, fighter supercruising at Mach 1,7 creates shock cone with temperature of 87 degrees Celzius. While PIRATE IRST can detect subsonic fighters from 90 km from front and 145 km from rear according to (somewhat outdated) publicly avaliable information, this range is 10% greater against supercruising fighter. At the same time, OLS-35 can detect subsonic fighter from 50 km from front and 90 km from rear. PIRATE’s own range is already comparable to that of fighter radars against 1m2 targets. (Note: Data used for both PIRATE and OLS-35 dates from 2008; it is possible that both have been improved in the mean time). Prototype Russian stealth aircraft PAK FA uses QWIP-based OLS-50M, so it is possible that QWIP technology may find its way into Su-27 family of aircraft. Identification can be carried out at 8 to 10 kilometers.

Parts of aircraft’s exhaust plume are also visible from front, which should present no problem for modern IRSTs that are capable of detecting AAM release due to missile’s nose cone heating.

Some IRST systems have laser rangefinder coupled with them, which means that they can be used to gain gun firing solution without usage of radar. While IRST is mostly immune to “beam turn” used to break radar lock, laser rangefinder may not be. Rangefinder, though shorter-ranged compared to IRST, would also have increased range at higher altitudes. IRST could also use sensitivity model (Atmospheric Propagation Model) to roughly estimate range and velocity of target without using any active sensors.

(Interesting to note is that Soviet MiG-31s were able to target SR-71 by using IRST; at speeds both aircraft were flying at in these situations, MiG-31s front surfaces would heat up to 760 degrees Celzius due to aerodynamic friction. SR-71 was not much better off; fortunately, order to attack was never given).

Astronomic IR telescopes can detect velocity of star down to 1 meter per second. This kind of precision would not be required for air-to-air combat, however, as closure rates between fighters could be up to 1 700 meters per second.

This means that stealth aircraft has no escape – if it attempts to increase effective range of its missiles, it has to increase speed – but this increases IR signature and allows it to be detected from larger distance. If it attempts to avoid detection, it has to reduce speed, which means that it has to come closer to IRST-equipped fighter.

USAF is obviously concerned about it – while IRST-equipped Super Tomcat was slated to be retired in 2008, it was hurriedly retired in 2006 under neoliberal stealth proponent Donald Rumsfeld. Both PAK FA and F-35 have IRSTs, but unlike PAK FA, F-35s IRST is optimised for air-to-ground missions, and is thus operating in appropriate wavelengths, reducing its range against aerial targets.

QWIP IRST such as PIRATE or OSF has some very useful advantages over “legacy” IRST. Aside from longer range, they can be tuned for sensitivity in certain IR band. While normal IRST operates in microwave to longwave IR bands, QWIP IRST can operate in very longwave bands, allowing for easy detection of objects that are only slightly hotter than the background, with difference being in single digit degrees of Cenzius. It can also use several bands in paralel, getting “best of the both worlds”.

While F-22 was designed to operate at high altitudes, as high as 15-20 kilometers, clouds only go up to 14 kilometers in some cases, with majority being below 4 500 meters – and even that only in tropics. All other stealth air superiority aircraft are similarly expected to operate at high altitudes.

Countering SAMs

Ground radars have to be above any obstacles to radar beam, which means that areas such as small valleys and canyons are usually not covered. Anti-radiation missiles and cruise missiles are very reliable against stationary radar sites; ARMs are better against mobile radars, as there is no radar that can pack up and leave in the time that ARM requires to reach it. SAMs are no different in that regard, and as such they can be kept shut down by use of anti-radiation missiles.

Without these two factors, however, stealth aircraft can be detected easily enough by long-wavelength radars, which completely ignore any practical amount of stealth coating, and are far less affected by stealth shaping measures than shorter-wavelength radars. These, then, can be used to guide IR SAM or IRST-equipped aircraft close enough for their IR systems to detect stealth aircraft.

Numerical issues

Numerical issues are probably the worst drawback of stealth. Stealth aircraft cost more and are harder to maintain than non-stealth ones. To demonstrate the actual impact, I will compare F-22 to two twin-engined aircraft designed to carry out similar mission to F-22s, but without stealth.

While F-22 costs 250 million USD per aircraft flyaway, cost for Tranche 3 Typhoon is 121,5 million USD, and cost for F-15C is 108,2 million USD. As such, 50 billion USD gives 200 F-22s, 411 Typhoons or 462 F-15Cs.

Sortie rate stands at maximum of 0,52 sorties/aircraft/day for F-22, 1,2 sorties/aircraft/day for F-15 and 1,2 – 2,4 sorties/aircraft/day for Typhoon (later value only assuming that design goals have been met). Thus, force bought would be able to support 104 sorties/day for F-22, 554 sorties/day for F-15C and 493 – 986 sorties/day for Typhoon.

Historically, quality of aircraft was always unable to compensate for force disparity once latter was above 3:1. As such, it can easily be seen that F-22 is, strategically, worse choice than Typhoon or F-15. And while all numbers are not yet avaliable, it cannot be expected that F-35 will perform any better in this crucial area relative to Gripen and F-16 than F-22 did relative to Typhoon and F-15. Me-262, while by any measure a revolutionary aircraft, was not used in large enough numbers to have impact against Allied fighters. In the end, Me-262 shot down no more than 150 Allied fighters, with 75 of them being lost in turn, in large part due to Allied superior numbers allowing them to catch Me-262 on take-off or landing.

BVR combat

Stealth aircraft are built under assumption that BVR radar-based combat trumps WVR combat. However, that assumption is unproven; neither AMRAAM or other BVR missiles were ever used beyond distance of 40-50 kilometers. In case of AMRAAM, usage was against aircraft with no radar, no IRST, no radar warners, no ECM, with badly trained pilots that were in most cases unaware they were under attack (and were not maneuvering as a consequence). Yet even in such perfect conditions, AMRAAM achieved 6 kills in 13 BVR launches, or Pk of 0,46.

During Desert Storm, in conditions identical to above, USAF F-15s launched 12 Sidewinders for 8 kills, for Pk of 0,67. For same F-15s, AIM-7 Sparrow achieved 23 kills in 67 shots, for Pk of 0,34.

Thus we have to take a look back at Vietnam. Why Vietnam? Simply because it was the last time US have fought somewhat competent opponent in the air. Even experience with IR missile suggests that Pk in combat against competent opponent will be far lower than above: AIM-9B achieved Pk of 0,65 in tests, which fell to 0,15 in Vietnam, to be improved to 0,19 with AIM-9D and J, whereas G model does not offer large enough sample for drawing conclusions. Yet even this was better than Pk for BVR missiles. While majority of AIM-7 shots were taken within visual range, during 1971-1973 in Vietnam, 28 BVR shots were made, resulting in 2 kills, one of which was a fratricide against an F-4 – a Pk of 0,071, as opposed to predicted Pk of 0,9 or more. During entire war, AIM-7D achieved 8% Pk, AIM-7E achieved 10% Pk and AIM-7E2 achieved 8% Pk. At the same time, guns had Pk of 0,28.

In fact, summary by Burton of kills made during Cold War has found that, out of 407 missile kills he studied, 73 were made by Sparrows in 632 firings, a kill rate of 11%. Sidewinder achieved 308 kills in around 1 000 firings. Out of all radar-guided missile kills, only four were made at BVR – two already described shots in Vietnam that were carefully staged outside of combat, and two similarly staged shots by Israeli air force. His summary of these 407 shots concluded that most targets were unaware and fired from the rear, and that there were almost no head-on BVR shots due to high closing rates. Only way to positively identify the target was by the eye.

When we take a look at the data above, a clear pattern begins to emerge: while Pk against incompetent opponent is significantly higher than against competent one, by a factor of almost five, relative weapons’ effectiveness remains unchanged: IR missiles achieve half the Pk of gun, and radar-guided missiles achieve half the IR missile’s Pk. Further, visual identification of target is still important, and is likely to remain so. In fact, during First Gulf War, majority of US casualties were due to the friendly fire, while in 1973 war Israeli pilots considered an on-board radar “essentially useless”, with Sparrow achieving one or no kills in that war.

This situation will even worsen for BVR-oriented aircraft in the future, as IRIS-T has capability to intercept and destroy BVR missiles. While it definetly will not be perfect, it will reduce number of missiles aircraft actually has to evade.

Time has also shown that maximum simplicity weapons and countermeasures, such as guns and flares/chaff, are usually most effective. This is unlikely to change.

Training issues

Pilot competence was always dominant issue in Air to Air combat. During German invasion of Poland, several Polish pilots became aces in 362 kph open cockpit fighters, when fighting against 603 kph Me-109, an early warning about importance of pilot skill. This was again shown when German fighters fought outnumbered in invasion of France, when higher-performance Spitfires and equal-performance Hurricanse fared poorly against Me-109s, which were flown by far more experienced pilots using tactics derived from actual combat as opposed to air shows and unrealistic peacetime exercises. Late in the war, Luftwaffe was unable to mount serious opposition not due to the lack of air frames – Allied bombing did not have major effect on German industry – but due to the lack of pilots.

Yet stealth aircraft’s large maintenance downtime prevents pilots from becoming familiar with their aircraft, and training enough in them. Modern fighters are also more complex than World War II ones, so lack of fighters is a very real possibility. AIMVAL tests, despite bias towards BVR, have also shown that ground controller assistance was more important to more complex and automated aircraft, and off-boresight missiles offered only slight improvement in results.

Conclusion

Stealth aircraft are expensive, and do not provide bang for the buck, in good part due to them being built on flawed reasoning and inaccurate assumptions. While they can be very useful against backward coutries, even in these cases larger numbers of cheaper aircraft will perform better. Assumptions behind stealth ignore lessons of combat to date, including the fact that pilot skill tended to dominate air combat (especially when combined with numerical superiority), as well as existing counter-stealth technologies.

Game-changing technologies were always simple in idea and execution, as relatively inexpensive. For comparision, stealth F-22 has cost of 12 690 USD per kg, F-35A costs 14 812 USD per kg, F-15C costs 8 504 USD per kg, F-16C costs 8 168 USD per kg, and Eurofighter Typhoon costs 10 942 USD per kg in its most expensive variant. It should be noted that F-22 lacks IRST and some of Typhoon’s systems, whereas F-35A is most loaded with electronics of aircraft listed. As such, stealth requirements add – without counting weight increase – 1 000 – 3 000 USD per kg. If the fact that F-22 is heavier than F-15C at least 7 000 kg is counted, stealth coating itself likely cost around 50 million USD, almost as much as my estimated flyaway cost of Gripen NG. IRST, on the other hand, costs around 1 million USD, and is far more useful than radar stealth.

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Is the F-22 really superior to all other fighter aircraft

Posted by Picard578 on December 1, 2012

USAF often touts F-22 as being the best fighter aircraft in the world. Is that really so? What are requirements for a good fighter aircraft?

By analyzing past wars we can see that following requirements have never changed:

  1. high agility at dogfighting speeds (currently in the medium subsonic to transsonic regime)
  2. superior situational awareness
  3. low cost
  4. high sortie rate
  5. capability to convert any split-second opportunity to the kill

High agility requires good acceleration, good turn rate, low energy loss and quick transients. Good acceleration and low energy loss require high thrust-to-weight ratio and low drag; good turn rate requires low wing loading, and quick transients require both. Energy state is important for gaining positional advantage and evading missiles.

Superior situational awareness requires not only having good situational awareness yourself, but denying it to the opponent. These requirements can only be met through use of passive sensors.

Low cost and high sortie rate are required for establishing a crucial numerical superiority over the opponent. Both are achieved by making the design as simple as possible.

Capability to convert any split-second opportunity to the kill is crucial in the dogfight, especially if multiple aircraft are involved on both sides, as it allows pilot to deny opponent the opportunity to reverse positional advantage, and allows him to kill more targets in the same timeframe.

With standard loadout of 50% fuel, 2 Sidewinder, 4 AMRAAM, F-22 has wing loading of 313,5 kg/m2 and thrust-to-weight ratio of 1,29. For comparision, with same loadout, Eurofighter Typhoon has wing loading of 284 kg/m2 and thrust-to-weight ratio of 1,28; Dassault Rafale’s values are 276 kg/m2 and 1,22. Su-27s values are 324 kg/m2 and 1,24. Thus, F-22 is inferior in wing loading to both Eurocanards, and has only slightly superior thrust-to-weight ratio compared to Typhoon. It is also only slightly superior to the Su-27 in wing loading, and somewhat more in thrust-to-weight ratio.

As such, it has slightly better turn rates than Su-27, and worse turn rates than Eurocanards. Its large weight will make it more difficult to F-22 to make transit from one turn to another, and its thrust vectoring will, if used, cause major energy losses. More about that later.

As mentioned, superior situational awareness requires not only having good situational awareness yourself, but denying it to the opponent. What this means is that aircraft must be capable of detecting and identifying the enemy completely passively. Currently, IRST and optical sensors are only types of sensors, except for Mk 1 eyeball, to posses such capability. F-22 lacks both, and as such has to either have an uplink to another platform – and such uplink can be detected and jammed – or to carry out both tasks World War II style, with pilot doing detection and identification visually. While F-22 was supposed to have FLIR, it was deleted as the cost-saving measure, and there are no plans to fit it.

Moreover, while some measures have been taken to reduce F-22s thermal signature, no major reduction was (or could have been) achieved, especially from the front. F-22 is also very large, increasing its detectability by the IRST. Thus, F-22 will be easily detected at ranges exceeding 80 kilometers by opponent using QWIP IRST.

Modern heat-seeking missiles also do not have to rely on engine exhaust for locking on the enemy aircraft, but can rather lock on to aircraft itself.

F-22 also isn’t undetectable to the modern radar, despite what some accounts say. While F-22s RCS of 0,0001 and 0,0014 m2 reduces detection range considerably, Typhoon’s radar (which has detection range of 185 km against 1m2 target) can detect it from distance of 18 to 35 kilometers. On the other hand, modern RWRs can detect LPI radars from ranges two or three times greater than such radars can detect target with RCS of 1 m2 at, thus making any use of radar an unwise course of action for F-22 (and any other fighter aircraft).

Low cost and high sortie rate are where F-22 feels least at home. Its flyaway cost is 250 million USD per unit, which is twice (205%) the flyaway cost of the most expensive non-VLO fighter aircraft – Eurofighter Typhoon – and has maintenance downtime of 45 hours per hour of flight, compared to the 8* hours for Rafale, 9* for Typhoon, 10 for Gripen and 19 for the now-ancient F-16 (* have to be confirmed). However, flyaway costs of these fighters, which are, respectively, 33%, 49%, 16% and 11-24% of F-22s, mean that it will be at 10:1 numerical disadvantage compared to Typhoon, and 26:1 disadvantage against Gripen.

F-22 is also incapable of converting split-second opportunities into kills. Reason for that is the fact that it carries all its armaments internally. It takes around half the second for gun doors to open; for missile bay doors it takes at least that much, and possibly more. Worse, Sidewinders it will be using in visual range dogfight are not simply ejected into air, but have to be lowered by mechanism; however, it is possible that such action will be performed while doors open.

Gun itself is the Gattling design. It offers maximum rate of fire of 6 600 rpm (110 rps), compared to 1 700 rpm (28 rps) for BK-27 used in Typhoon and Gripen, and 2 500 rpm (42 rps) for GIAT-30 used in Rafale. However, firing rate alone cannot be used as a measure of effectiveness.

First, Gattling gun takes some time to achieve full firing rate. While M-61A2 takes 0,25 seconds to spin up to its full firing rate, fact that F-22 has to open bay doors to fire increases that time to 0,75 seconds. For revolver cannon, time is 0,05 seconds. Thus, in first second, F-22 will have fired either 13 or 68 rounds (depending on wether gun doors were opened before or after press on trigger); Typhoon would have fired 27 rounds in the same time, and Rafale 40 rounds.

Second, aircraft now are highly resistant. Thus, per-hit damage and weight fired may be more important than number of projectiles. At projectile weight of 100 g for M-61, 260 g for Typhoon and 244 – 270 g for Rafale, F-22 fares worst in per-hit damage category. For total damage, in first second F-22 will have fired 1,3 to 6,8 kg, Typhoon 7 kg and Rafale 9,8 to 10,8 kg of ammunition.

Third, rotation of gun barrels creates vibrations, which means that Gattling design will be less accurate (more spread) than single-barreled designs, and problem will only increase as gun keeps firing.

While F-22 is supposed to kill opponent at BVR, it only carries 6 BVR missiles. With usual 0,08 Pk ratio against same-era threats, it will take two F-22s to kill a single enemy aircraft. That is made even worse by the fact that F-22 not only has to radiate in order to lock on the enemy aircraft, but has to get close enough to penetrate any jamming – distance that was regularly around 1/3 of maximum radar range; in F-22s case, it will be 50 – 80 kilometers against 1 m2 target, such as Typhoon or aircraft with comparable frontal RCS (J-10?) in air-to-air configuration.

F-22s maximum speed of Mach 1,8 – 2,25 and supercruise speed of Mach 1,5 – 1,7 are better than those of most competitors, as Eurofighter Typhoon – the second-fastest supercruiser – can achieve “only” Mach 1,3 when in combat configuration. Thus, F-22 can choose to run if it finds itself outnumbered too much, but if it does choose to attack, it will most likely be forced to engage the opponent in the visual range.

How maneuverable F-22 is

Many say that F-22 is the most maneuverable fighter aircraft by virtue of its thrust vectoring. So, I have decided to take a closer look at various claims about F-22s agility.

F-22 is the most maneuverable fighter aircraft out there

Some claim that F-22 is the most maneuverable and agile fighter aircraft out there, due to the thrust vectoring. That claim, however, is false.

To execute a turn, aircraft requires lift to pull it around the turn. Even civilian jets make sharper turns this way, by banking. Amount of lift can be roughly estimated through wing loading figures, with the caveat that LEX and close-coupled canards do provide the additional lift during high-alpha maneuvers by strengthening vortices created by the wing.

However, while F-22 does have LEX, it is not the only one. Dassault Rafale has both LEX and close-coupled canards, Saab Gripen has close-coupled canards, and Eurofighter Typhoon, while not having either, does have vortex generators at sides of the fuselage.

Thus, actual lift at high AoA could be estimated by comparing length of forward portion of the wing to the aircraft’s weight. This method is only of limited accuracy, however, it is more accurate than standard wing loading figures for high alpha maneuvers, as large portion of wing stalls in such circumstances.

F-22 has combat weight of 24 883 kg and combined wing leading edge length of cca 12,58 meters, which becomes 20,56 meters when LEX and air intake leading surface are taken into account. Thus loading value will be 1210 kg per meter. However, LEX-generated vortices will improve value.

Eurofighter Typhoon, on the other hand, has combat weight of 14 483 kg and combined wing leading edge length of ~18,3 meters along with canards. Thus its loading value will be 791 kg per meter, or slightly higher, but as with F-22, vortices will improve value – this time vortices generated by strakes at sides of Typhoon’s hull. Both Typhoon and F-22 have similar wing sweep and high-lift devices, so actual lifting area per meter will be the same, except maybe for canards.

At lower angles of attack, when entire wing area is used, F-22 will have wing loading of 319 kg/m2 in standard combat configuration, and Eurofighter Typhoon will have wing loading of 283 kg/m2. Thrust loading ratios will be 1,28 for F-22 and 1,25 for Eurofighter Typhoon.

We can thus see that, while F-22 has thrust-to-weight ratio advantage, Eurofighter Typhoon has both lower combat weight and lower wing loading at combat weight, and thus has better maneuvering performance. Dassault Rafale will have similar advantages, although its canards act more like F-22s LEX, which makes it for two aircraft that have better maneuvering performance than F-22.

F-22 is comparable to F-15C (claim made by Pierre Sprey)

Comparing it to the F-15C, we see two things: wing loading and thrust-to-weight ratio that are very similar, with F-15C having slight advantage. While F-22 is larger and heavier aircraft, it is also unstable, improving its response time and removing resustance of aircraft towards the continued turn. It also has LEX, which improves lift at high angle of attack.

While its internal missile carriage adds weight and frontal area, that is cancelled out by reduced drag due to lack of external stores.

F-22 is worse than F-16

F-22 and F-16 have two major things in common: both are relaxed-stability designs and both have LEX. As such, similar wing loading figures and thrust-to-weight ratios will result in similar maneuverability, especially since F-16 was designed to achieve optimum performance when two wingtip AAMs are present.

With 50% fuel, 2 Sidewinder and 4 AMRAAM F-16C has wing loading of 392 kg/m2, thrust-to-weight ratio of 1,186 and weights 10 936 kg. F-22 has wing loading of 313,5 kg/m2, thrust-to-weight ratio of 1,29 and weights 24 579 kg. Thus, while F-22 will suffer maneuverability penalty due to its size and weight, it is unlikely that F-16C will be able to outmaneuver it.

With F-16A it is a different story. With empty weight of 7 076 kg, it has wing loading of 349,5 kg/m2 and thrust-to-weight ratio of 1,29 (figures for 50% fuel and 2 Sidewinder). While its wing loading is higher than F-22s, F-16A is far lighter and smaller, so it is possible that it could be capable of matching the F-22.

Conclusion

To conclude, while Pierre Sprey’s notion that F-22 is no more maneuverable than F-15C is not supportable, those that insist F-22 is the most maneuverable fighter aircraft in the world are equally wrong. Indeed, new fighters such as Eurofighter Typhoon or Dassault Rafale will have better maneuvering performance with virtue of their better aerodynamics and superior attributes (wing loading, thrust-to-weight ratio, etc). F-22 also does not meet force size requirements.

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On AviationIntel F-22 vs Typhoon article

Posted by Picard578 on November 24, 2012

http://aviationintel.com/2012/07/28/in-response-to-reports-of-simulated-f-22-raptor-kills-by-german-eurofighters/

 

While author is indeed correct that training sorties do not necessarily mean that one type of aircraft is superior, multiple sorties can, when analyzed properly and assuming that setup is known, provide some information about respective fighter’s capabilities.

Huge control surfaces and thrust vectoring are useful for high-altitude and low-speed maneuvers, not in types of maneuvers required for close-in combat (transsonic low-altitude maneuvers). In fact, thrust vectoring is dangerous as it bleeds off energy, leaving fighter defenseless if it does not manage to get a kill immediately upon using it Secondly, German Typhoons in the exercise had no helmet-mounted sights, and as such had to point nose at F-22s to get a lock.

Modern radar warners, such as those carried by the Typhoons, are very capable of detecting even newest LPI radars. In any scenario where IRST-less Typhoon and F-22 went against each other with no AWACS support, both sides would be limited to visual detection.

In the end, visual-range combat is more likely than not to be decisive between fully equipped 4,5-th/5-th generation aircraft. As such, while F-22 is a capable dogfighter, it cannot be counted on to have a major impact in a war due to high cost and low sortie rate.

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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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Cleaning up Red Flag Alaska F-22 vs Typhoon debate

Posted by Picard578 on October 20, 2012

Since Eurofighter Typhoons defeated F-22s at Red Flag Alaska in June 2012, discussion has produced many claims. I will address some of them here:

1) WVR combat is only small spectrum of air combat.

Yes, and no – it mainly depends on numbers, and who you are shooting at. As enemy numbers, as well as quality of each pilot and aircraft, increase relative to BVR-oriented force, effectiveness of BVR missiles drops – while qualitatively and quantitatively superior air force might achieve per-missile probability of kill as high as 50% for BVR missiles (against non-maneuvering enemies with no jammers), BVR missiles have never achieved more than 10% per-missile Pk against force that has been comparable in all stated factors – and it must be kept in mind that BVR-oriented aircraft are always more complex (and thus both more expensive, and flying less often) than WVR-oriented ones.

In short, BVR combat is excellent when facing enemies you don’t need it against, but doesn’t work when needed most.

2) German Typhoons had helmet-mounted sights and this allowed them to dominate more maneuverable F-22

Incorrect. Exercise was held in June 2012, and only from July on did German Typhoons start getting HMD. As such, Typhoons at Red Flag had to point their nose at the F-22s to get a lock.

That can easily be confirmed by comparing helmets of Typhoon pilots at exercise:

http://cencio4.files.wordpress.com/2012/07/closeup1.jpg

http://cencio4.files.wordpress.com/2012/07/df_3029_neuburg_18-07-12.jpg

with HMD one:

http://www.defenceweb.co.za/images/stories/AIR/Air_new/Eurofighter_typhoon_helmet.jpg

which can be seen to be less round.

3) Typhoon’s IRST can detect F-22 from 50 kilometers

While that claim might not be incorrect – and indeed most likely isn’t – it has no relation to exercise itself, as Luftwaffe Typhoons had no IRST.

(Photo is of Typhoon from exercise, same one which “bagged” three F-22 “kills”).

4) Typhoons were slicked-off

While Typhoons did not carry any missiles or tanks in exercise, Typhoon does have a number of hard points that are permanently attacked to an airframe. In any case, heaviest – BVR – missiles would be ejected, and even some WVR missiles expended, well before Typhoons got in the merge. Neither F-22 or Typhoon had missiles.

Grune’s exact words are:

“We pulled off all the tanks to get most Alpha on it (Typhoon), and it is an animal with no tanks”.

5) F-22s were performance-limited

One of claims I have found was that F-22’s maneuver envelope has been limited due to oxygen problems. However, performance limitations to F-22 have only been enforced some time after the exercise, and pilots also had their oxygen vests, which have only been removed a week after exercise itself.

6) F-22s BVR capabilities were “overwhelming”

That claim, while not incorrect, was not about Typhoon vs F-22 exercise, but was a comment on earlier exercises where F-22s and Typhoons worked together against agressor F-16s simulating threat aircraft – most likely Cold War era Su-27 and MiG-29, as USAF has no reliable data on newest Russian types. As such, effectiveness of simulated BVR missiles in such exercises is far overstated even beyond unrealistic Pk assigned (Pk in question is around 90%, as Typhoons in that exercise got 16 kills from 18 simulated missile shots).

7) Typhoon was unable to get within 20 miles of F-22 without being targeted

That claim is result of Grumbercht’s quote that has been taken out of context:

“If I get everything right BVR, I’m not going to get closer than 20 miles.”

That quote seems to be referring to the Red Flag exercises, and not earlier Typhoon/F-22 WVR dogfight, and should probably be interpreted as “I’m not going to have to get closer than 20 miles”.

EDIT 7. 4. 2013.

This is excerpt from Jane Defense Weekly, found on Internet:

TYPHOON ‘HOLDS ITS OWN’ AGAINST RAPTOR
Immediately before Red Flag JG74 took part in Exercise ‘Distant Frontier’, which included eight one-on-one basic flying manoeuvre (BFM) sorties against US Air Force F-22A Raptor air superiority fighters. The aim was to help pilots of both types gain a fuller understanding of the capabilities, strengths and weaknesses of each other’s aircraft in order to allow them to operate together more effectively during Red Flag (where both types were assigned to the ‘Blue’ force) and during any subsequent ‘real world’ coalition operations.

During the process the pilots of JG74 gained a real boost to their confidence, said Col Grüne. “There were two mornings where we flew against them 1v1. We pulled off all the tanks to get the most alpha [angle of attack]; the Eurofighter really is an animal with no tanks.

“We expected to perform less with the Eurofighter but we didn’t … they were as impressed by us as we were impressed by them.”

Col Pfeiffer went into a little more detail. “In the dogfight the Eurofighter is at least as capable as the F-22, with some advantages in some aspects,” he said. “This is without the helmet. The Raptor’s unique capabilities are overwhelming, but as soon as you get to the merge, which is [admittedly] only a very small spectrum of air combat, the Typhoon doesn’t necessarily have to fear the F-22 in all aspects. We gain energy better than the F-22 when we are slow, for example.”

Red Flag demonstrated that the Typhoon had other advantages – being able to stay on station longer than the F-22, for example – but could not compete with the Raptor’s dominance in the beyond-visual-range (BVR) arena.

Both sides were coy about the relative kill:loss ratio gained during the Typhoon/F-22 BFM sorties, but Col Grüne was upbeat. “The only thing I can say is that I agreed to put out some whisky if they came back with some good performances … and I paid for quite a lot of whisky,” he said.

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