Posted by picard578 on April 27, 2013
United States, as well as many of its allies, have always looked towards increasing range of combat as much as possible. Just as often, it failed, especially in the air, where technologists’ dream of destroying enemy air force before it reaches visual range remains unfulfilled to this day. Main reason for it is that BVR combat is, conceptually, operationally and technologically, massively complex affair. Exact extent of visual range depends on size of aircraft – while maximum visual detection range for MiG-21 is 8,5 kilometers, it is 15,37 kilometers for F-14. Smoke can extend that range by over 5,6 kilometers; while by other info, definition of BVR combat considers “BVR” to be anything beyond 37 kilometers. Optical devices such as IRST or TV cameras can extend range of visual identification of aircraft – PIRATE can identify enemy aircraft at 40 kilometers in ideal conditions.
BVR theory states that future air combat will be comprised of large “missile truck” aircraft flying at supersonic speeds, launching radar-guided missiles at targets that are way too far to be identified visually. This has resulted in development of aircraft that are very heavy (most weight little less or more than 15 metric tons empty – for example, Tornado ADV weights 14,5 metric tons, and F-22 weights 19,7 metric tons), carry large amounts of missiles, and are far more expensive and much less reliable than aircraft with bias towards visual-range combat. Yet BVR combat still has not taken lead role in air-to-air combat.
We can in fact draw paralels between modern air-to-air combat and modern infantry combat. While infantry has access to sniper rifles that allow ranges of around two kilometers, and old battle rifles had ranges of 500-1000 meters, most combat happens at ranges no greater than 100 meters, and never involves single shooters. In Vietnam, M-14 proved basically useless as basic infantry weapon when compared to AK-47. Reason for this is that, while large battle rifles were useful in static warfare of World War I, World War II and later wars saw mobile warfare develop with combat happening at low ranges, thus requiring lighter, faster-firing weapons. Result was development of sub-machine guns, as well as first assault rifles (such as German MP-44, renamed StG-44, which was world’s first assault rifle and provided inspiration for very successful AK-47; both were used by Vietcong).
In air-to-air combat, BVR missiles fill the niche of old battle rifles and modern sniper rifles, WVR missiles fill the niche of modern assault rifles, while gun fills niche of combat knife. While gun is most versatile weapon of the lot – it can be used for air-to-air work, close air support, firing warning shots towards aircraft violating forbidden airspace – it is not often used in air-to-air combat and is treated purely as fallback weapon in case missiles have been expended.
It is often forgotten is that g forces in tracking turn are a square of speed. Thus, in WVR combat, if missile travels at Mach 3 and fighter aircraft travels at Mach 0,5 (corner speed of many modern fighters) and can pull 12 g maneuvers, then missile needs to pull 432 g to hit fighter aircraft, or 133 g if fighter is travelling at Mach 0,9. This gives a Pk of 14 – 45 % for WVR missiles, as even IRIS-T can “only” pull 60 gs. But even that is only from ideal position (directly behind enemy aircraft, nose pointed towards opponent’s engine nozzles), which means that attacking fighter aircraft must be capable of putting itself into said position. Lower Pk is more likely due to nature of WVR combat, which is fought at corner speed whenever possible, and especially when countermeasures such as flares and jammers are taken into account In fact, it is possible that actual Pk may be even lower than 14%, though it most likely won’t be, as increased survivability provided by countermeasures will be countered by the fact that IR missiles themselves are passive, and aircraft does not need to use active sensors to use them, so some pilots simply won’t notice they are attacked until they get blown off the sky; this however is assuming that aircraft does not have 360*360 degree coverage with missile warners, be it IR-based, radar-based, UV-based or combination. If missile is fired outside ideal position, it has to maneuver in order to point its nose towards the target, thus lowering probability of kill; there is also a danger of targeted aircraft simply flying out of missile’s field of view. This danger is also present with active-seeker BVR missiles. In BVR, AIM-120 travels at Mach 4, and can pull 30 g within its NEZ, yet it would need 768 Gs to reliably hit a modern fighter which is maneuvering at corner speed of Mach 0,5, or 237 Gs if target is still at standard cruise speed of Mach 0,9, giving Pk between 3 and 13%; this fits perfectly with 8% Pk demonstrated against (mostly) maneuvering aircraft without ECM to date. If fighter is maneuvering at corner speed, but is still limited to 9 g by FCS (is not in override), BVR missile Pk is 5,2%.
Further, even though BVR missiles have maximum range of over 100 kilometers, their effective range against aircraft in attack is 1/5 of that – around 20 kilometers – and target beyond 40 kilometers can feel free to maneuver without even taking any possible missile shots into account, as only way these would hit is luck. One of reasons is that BVR missiles follow ballistic trajectories – AIM-120C-5 allegedly has motor burn time of 8 seconds, which gives range of around 10 kilometers before motor burns out. At ranges greater than 8 kilometers, attacking fighter can still choose wether to outmaneuver or outrun the BVR missile; at distances less than that is missile’s no-escape zone, where aircraft cannot outrun the missile, it has to outmaneuver it, but such distances automatically mean that combat is not longer beyond visual range. Ranges stated are also only true at high altitude against aircraft in attack; at low altitude, effective range of BVR missile is reduced to 25% of its range at high altitude, and range against aircraft in flight is 1/4 of that against aircraft in attack.
Proximity fuses on missiles can trigger explosion of missile if anything (like a bird) flies nearby. Warhead itself has lethal radius of 10-12 meters for late AIM-120 variants.
Missiles are not the only problem with BVR combat. There are also questions of reliable IFF, penalties for using active sensors in combat, weight, cost and complexity penalties on weapons systems caused by systems required for BVR combat, as well as training penalties caused by aforementioned penalties on weapons system.
Training penalties are probably most damaging. In 1940, Germans – outnumbered 1,5 to 1, and using inferior tanks – overran France in three weeks because they had superior personnell – both commanders and soldiers. On the Eastern Front, German Panther and Tiger I tanks achieved favorable exchange ratios against more numerous – and in many aspects superior – Soviet T-34-85, IS-I and IS-II tanks, and General Guderian favored increased production of Panzer IV equipped with long cannon over production of more capable, but more expensive, less reliable and less strategically mobile Panther (for each Panther, Germany could have produced two Panzer IVs; for Tiger I, ratio was four Panzer IVs for each Tiger). After Gulf War I, General Schwarzkopf said that the outcome of Gulf War I would have been the same if the U.S. and Iraqi armies had exchanged weapons, a statement similar to one given by IAF General Mordecai Hod after 1973 war, in which he stated that IAFs 80-1 victory against Arabs would have remained the same if both sides had exchanged the weapons. Yet BVR-oriented aircraft, low in number and hugely complex, cannot be used for training often enough. While technologists typically counter this argument by pointing to increased ability of simulators, that argument is not realistic: simulation is never perfect, as quality of the end result is never better – and is often lot worse – than quality of data used to compute it. Simulators often misinterpret reality, and support tactics that would get pilots killed in real combat. Further, simulators cannot prepare pilot for handling of shifting g forces encountered during both dogfight and BVR combat maneuvering.
Meanwhile, using active sensors is outright suicidal in combat. Aircraft using active sensors will be quickly detected and targeted by modern defense and EW suites, and unique radar footprint may allow for BVR IFF identification. This can allow passive aircraft to launch BVR infrared or anti-radiation missile, and/or to use data acquired to achieve optimal starting position and speed for following dogfight. Only countermeasure is to turn radar off and rely solely on passive sensors. IRST is especially useful here, as while air temperature at 11 000 meters is -56 degrees Celzius, airframe temperature due to air friction can reach 54,4 degrees Celzius at Mach 1,6 and 116,8 degrees Celzius at Mach 2. It is also very difficult to impossible to jam, and offers greater angular resolution than radar. Result is that flying from cloud to cloud is still a viable combat tactic; but it is not perfect either, as clouds are not always present and may not be close enough for aircraft to avoid detection in the mean time.
As for IFF issue, only reliable IFF method is visual one, especially since pilots often turn IFF transponders off to avoid being tracked. Visual IFF, unless assisted by optical sensors (be it camera or IRST), usually requires two aircraft to approach within one mile or less (sometimes as close as 400 meters), whereas minimum range of AIM-120D is 900 meters. But even when assisted by visual sensors, it may not always be reliable, as opponent may be using fighters of same type or at least of very similar visual signature.
Aircraft designed for BVR combat are significantly more complex and costlier than aircraft designed for WVR combat; I will demonstrate this on examples. F-15 was designed for BVR, and F-16 for WVR, but with similar technology; F-15C costs 126 million USD whereas F-16A costs 30 million USD, a 4:1 difference. F-15s successor, and currently most capable BVR platform in the world is F-22, whereas Gripen C is F-16s successor (in idea and aerodynamics, not in lineage), though with far more BVR capability. F-22A costs 262 million USD, compared to Gripen C’s 44 million USD, or 6:1 cost difference (all costs are unit flyaway costs in FY-2013 USD). Aside from smaller number of units bought, increased complexity means that these units fly less often: F-22s maintenance downtime is 45 MHPFH, compared to Gripen’s 10. Thus for 1 billion USD, one will have 3 F-22s flying 11 hours per week, or 22 Gripens flying 336 hours per week. Even Gripen’s cost per flight hour is 1/13 of F-22s, 4 700 USD vs 61 000 USD. Older fighters also follow this outline, with F-5E costing 940 FY1980 USD per hour compared to F-4Es cost of 2 733 FY1980 USD per hour, a 3:1 difference. Weapons are more expensive too: while AIM-120D costs 1 470 000 USD per missile, IRIS-T costs 270 000 USD, a 5:1 difference.
Weight difference is also significant. Gripen C weights 6 622 kg empty, compared to 19 700 kg empty for F-22; F-16A weights 7 076 kg compared to 12 700 kg for F-15C. It can be seen that WVR fighters are significantly smaller and lighter than contemporary BVR fighters. And with cost of 6 645 USD per kg, Gripen C is significantly cheaper per unit of weight than F-22 which costs 13 300 USD per kg, whereas F-16A costs 4 240 USD per kg, which when compared to F-15Cs 9 921 USD per kg gives similar ratio to F-22/Gripen one.
Even if previous shortcomings are disregarded, BVR combat is not always possible. If fighters are tied in defending a fixed point, or if enemy attack is not noticed on time (distance between air fields is too low, enemy manages to sneak up by using the terrain) only option is engaging in visual-range combat.
Past air-to-air combat experience also suggests that days of BVR combat being primary form of air-to-air combat are still far away, if they ever come. First BVR craze happened in 1950s, when USAF procured the “century series” fighters, and USN bought F-6D Missileer and F-4H-1 Phantom II, latter of which carried Sparrow missile; former used huge Eagle missile, similar to F-14 with its Phoenix missile. Phantom was also adapted into USAF as F-4C Phantom II. Soon, other BVR fighters – F-111, F-14, F-15 – followed. Soviets, in an arms race that was actually more about prestige than about military capability, decided to counter this development with BVR fighters of their own: Yak-28, Tu-28 and MiG-25 as counters to 3rd generation BVR fighters, with F-15 being countered by Su-27.
These fighters all followed logic of “bigger is better”. Bigger radar – focus of the logic – required bigger airframe, which in turn required bigger engines. Both weight and complexity spiralled upwards, creating fighters that were costly, flew very few sorties and had maneuvering capabilities more typical of strategic bombers than of fighter aircraft – logic being that they will not have to maneuver, as they will destroy the enemy far before it comes to the merge. Exception to this as far as US fighters are concerned are F-15 and F-22, but even that was only due to influence of Boyd’s Fighter Mafia; Su-27, being designed to counter F-15 and built with same requirement of high BVR capability and high maneuverability, also follows basic logic of large but very agile aircraft with large radar. All aircraft mentioned as being agile were developed after Vietnam War, in which failure of BVR-only logic was aptly demonstrated; yet they all relied on using superior range and technology to defeat superior numbers of “less capable” WVR fighters.
But in practice, BVR promise fell short. During the entire Cold War, 407 kills were made with missiles in eight conflicts, with reliable data for ninth conflict, Iran-Iraq war, not being avaliable. Only four saw use of radar-guided BVR missiles: Rolling Thunder and Linebacker in Vietnam, Yom Kippur War, and conflict over Bekaa Valley. In total, 144 kills were made with guns, 308 with heat-seeking missiles and 73 with radar-guided missiles. What is interesting to notice is that, while percentage of gun kills in the latest conflict, Bekaa Valley, was lower than in any other, it also held second-lowest percentage of radar-guided missile kills, and highest percentage of IR missile kills. Out of 73 radar-guided missile kills, 69 were scored within visual range, with remaining four being carefully staged outside combat. Out of these kills, two were made by Israel under intense US diplomatic pressure to establish BVR doctrine, and two were made by US in Vietnam, with one of US kills being a freindly-fire incident, a F-4 mistakenly identified as MiG-21. As there were 61 BVR shots during entire Cold War, this results in Pk of 6,6%, compared to 15% for IR missiles, and to promised BVR missile Pk of 80-90%. Even though majority of BVR missile shots in Vietnam were made from visual range, Pk was still 9,6%. While F-4 and F-105 did score numerous aerial victories in Vietnam, all except two mentioned BVR kills were made within visual range, and of these, many were achieved by gun after Top Gun course was established, securing USAF an unquestionable pilot superiority. In fact, F-4 consistently underperformed until it was given gun and pilots were taught how to dogfight, and Navy F-8, with its far lower wing loading and mass, performed far better against MiGs. And even today, missile tests are carried out against drones with limited maneuvering capability, as these are usually rebuilt old aircraft (for example, QF-4 which is a rebuilt F-4).
Further, in these 407 kills, most targets were unaware and fired at from the rear, and there were almost no head-on BVR shots due to high closing speeds of aircraft involved. This shows that good rearward visibility from cockpit is still important despite all technological advancements.
Two post-Cold War wars in Iraq are offered as examples that BVR theory has finally reached maturity and that BVR combat now is prevalent form of aerial combat. Out of 41 kills in Desert Storm, 16 involved use of BVR shots, but only five kills are known to have been made at BVR. Even then, longest-ranged kill of these five certain BVR kills was made at distance of 29,6 kilometers, and one of remaining BVR shots was made at night from what would have been visual range in daytime. Desert Storm was first conflict where more kills were made by radar-guided missiles than by IR missiles – 24 vs 10. While 24 radar-guided missile kills out of 88 shots gives Pk of 27%, F-15s killed 23 targets in 67 shots with AIM-7 (Pk 0,34), while Sidewinder launches from F-15 resulted in 8 kills from 12 shots (Pk 0,67). While F-16s launched 36 Sidewinders and scored 0 kills, at least 20 launches were accidental due to poor control stick ergonomy; F-16s in question themselves were overweight F-16Cs, so-called “more capable” variant equipped with BVR capability and tons of electronics. Iraqi Freedom was likely similar in this aspect. AIM-120, meanwhile, demonstrated BVR Pk of 0,46 in Iraqi Freedom and Allied Force (6 kills out of 13 shots).
Navy and USMC themselves achieved 21 Sparrows and 38 Sidewinders in the Desert Storm, achieving one kill with Sparrow (Pk=4,76%) and two with Sidewinders (Pk=5,26%). Reasons for such low Pk are unclear, though given F-16s problems it is possible that most launches from F-18 were accidental.
Claim that USAFs combat record proves maturity of BVR combat or even missiles in general is misleading, however. Targets that were fired at were in vast majority of cases unaware they were being fired at and thus did not take any evasive action; no targets had electronic countermeasures, support from stand-off jammers, nor comparable BVR weapon (be it radar-guided, IR or anti-radiation BVR missile). When targets were aware they were targeted and thus did take evasive action – such as when two Iraqi MiG-25s illuminated two F-15Cs with BVR radar in 1999 – BVR shots were ineffective (in example cited, US fighters made 6 BVR shots to no effect). There was also constant AWACS avaliability in both Gulf Wars, and in all wars US/Coalition aircraft had numerical superiority. Iraqi pilots also were badly trained, and most Iraqi jets did not have bubble canopy like F-16, but one that did not provide rearward visibility and was in many cases heavily framed, limiting pilot’s ability to acquire missile visually in addition to total lack of warning devices.
I will also note here a report by Air Power Australia group, found here. Some assumptions have to be fixed: missiles have demonstrated 0,34 – 0,46 Pk against non-maneuvering opponents with no ECM; 0,46 figure is for AIM-120 and is one I will use here. Thus 54% miss value is attributed to factors that have no connection to ECM or maneuvering. Out of remaining 46%, there is 93% for chance of miss. Thus BVR missile Pk against aware, maneuvering opponent using modern ECM suite is around 3%. Considering that most opponents shot at by BVR missiles during Cold War had no ECM, and some at least did not notice a missile, thus failing to take evasive action, this can be considered to be in line with demonstrated Pk.
Latest BVR craze has resulted in F-22 and F-35, both of which are utterly expensive and maintenance intensive, and latter of which is in its major characteristics more similar to century series than modern fighter aircraft. F-35 in itself is utterly incapable of handling itself in close combat due to large weight, high drag, high wing loading and low thrust to weight ratio. It can also carry at most 4 BVR missiles in internal bays. With this in mind, claims by manufacturer that F-35 is 4 times as effective in air-to-air combat as next best fighter in the air would require probability of kill for BVR missiles of 80-90%, and opponent’s complete inability to engage F-35 itself at BVR range. Track record of BVR missiles to date as well as development of infrared BVR missiles and long range QWIP IRST sensors mean that any such assumptions are nothing more than wishful thinking on part of sales department and high technology addicts.
Result is that eye remains most important sensor on the aircraft, and pilot who looses sight of the opponent during maneuvers is likely to be quickly shot down. Secondary are onboard passive sensors such as IRST and RWR, followed by offboard sensors – both passive and active – whereas onboard active sensors take last place. Human factors still trump technology, and higher cost does not mean more capability in a real world combat scenario – even with missiles, both BVR and WVR, pilot has to know how to achieve ideal firing solution, and more electronics means more weight, which hurts airframe performance.
Considering that BVR missiles generally cost 2-5 times as much as IR WVR missiles, yet are 44% as effective, it is easy to calculate that they are only 8,8-22% as cost-effective as IR missiles, while in most cases not offering noticeable advantage in engagement range, and at same time incurring cost and capability penalties on aircraft designed to use them.
For end, I will adress an argument that is obviously invalid but very often does come up anyway: one of exercises in which F-22 “dominates” against “legacy” fighters, with kill ratios between 10:1 and 30:1. But these exercises are bogus, as they depend on incorrect assumptions about air combat to produce results. In them, most kills are achieved at BVR as BVR missiles are assigned Pk of 90%, despite never achieving such performance; enemy anti-radar measures such as anti-radiation missiles or missile cueing with RWRs are not allowed; most F-22s opponents went without avionics upgrade for a very long time and thus likely don’t have ability to jam AESA radar; Red Force simply charges in, from known vector; and real fleet cost and fleet readiness are not represented, which means that F-22 doesn’t face force ratios it would face in real world. Due to that, exercises are only useful as a propaganda tool, having no connection to reality of air combat, and using them to argue for usefulness of stealth and BVR combat is nothing more than a circular logic.