Introduction

This is a revision of previous article, meant to adress several problems that I have either noticed myself or were brought to my attention after posting it. First problem is that while a good design, original FLX still had problems. It simply did not have enough space in the air frame to achieve required 40% fuel fraction. It was also not nearly as light and small as I wanted it, being of similar size as Gripen C, even larger in some aspects; this resulted in M88 engine being insufficient to achieve planned thrust to weight ratio values (specifically, thrust-to-weight ratio above 1 at dogfighting configuration of 50% fuel + 2 IR AAMs and dry thrust), and stronger M88-ECO being required. Lastly, I had probably underestimated its cost per kg.

Historical lessons

“History is a vast early warning system.”

Norman Cousins

When designing a fighter aircraft – or any weapon – there is a basic question: should one go for simplest solution, or accept a level of complexity in hopes of achieving better performance? How much simple or complex weapon can become before excess simplicity, or excess complexity, harm its performance? Only way to answer that question is to look at the real war, and apply lessons learned through research in designing a weapon.

In Poland campaign in World War II, several Polish pilots became aces in open-cockpit 225 mph biplanes when fighting against 375 mph Messerschmitt 109, clearly showing that pilot skill is more important than weapons characteristics. Later, over the Dunkirk, British pilots did poorly despite using fighters comparable to Me-109, primarly due to inexperienced pilots, unrealistic training (unlike Luftwaffe, 1930s RAF did not practice squadron-on-squadron training) and outdated tactics – such as three-ship “vic” formation, which was far less flexible than German “finger four”. Aside from flexibility in tactics, “finger four” system allowed aircraft to effectively cover each other from surprise bounces.

RAF headquarters’ insistence on close control of fighters proved detrimental, and small number of pilots and fighters avaliable to 11th Group caused fatigue, which when combined with the fact that RAF was still switching to finger four system and that many pilots were grossly undertrained led to heavy losses. RAF did have advantage in that it fought over a friendly territory, which meant that 50% of pilots shot down were safely recovered, compared to 0% for Luftwaffe. Fighter command’s preference for grass fields over actual runways allowed entire squadrons to take off at the same time, and Germans failed to attack 11th Group bases and control systems.

German fighters did not use belly tanks, which limited them to 20 minutes over England. This, plus Goering’s insistence on close escort of bombers, caused heavy losses in aircraft, and more importantly, pilots – aircraft were replaced at an adequate rate, but pilots were not. When Allied started bombing Germany, small P-51 was second longest-ranged fighter in the US arsenal (800 mile combat radius, compared to 900 mile for P-38 and 600 miles for P-47). By spring 1944, P-38 was replaced by P-51 due to huge losses and poor kill/loss ratio, caused by its huge size, low maximum g, poor roll rate and poor dive acceleration; two engines were also a survivability handicap, since aircraft that lost one was quickly finished by German fighters. P-51D, on contrary, could match or surpass turn rate of FW-190A and Me-109G, was far faster and could match them in roll. Similarly, German heavy bomber-destroyer fighters were easily shot down by Allied lighter air superiority fighters such as P-51 and Spitfire. In the end, pilot attrition rendered Luftwaffe ineffective – by September 1944, it was receiveing 3.000 new fighters and 1.000 new pilots per month. Heavy P-47 proved inferior air superiority fighter to P-51 and was pulled from air superiority role alltogether; unlike P-38, it did prove a very successful CAS aircraft.

Me-262 was clearly superior to Allied turboprop fighters, and by March 1945 over 950 have been delivered. Yet shortages of fuel and pilots meant that largest number flown in a single day was 55, and they were in danger of being attacked whenever taking off or landing – and where Me-109 was capable of being road- and open field- -based, with maintenance often carried out under bridges and most infrastructure buried, Me-262 required dedicated runways. In the end, its low numbers meant that it had no impact on war despite huge performance advantage over Allied fighters.

At beginning of the war, Spitfires used 6 .303 caliber machine guns which were ineffective even against fighters. Me-109E carried two 20 mm cannons which were effective against fighters but had low muzzle velocity and rate of fire. Spitfires were later upgunned to two 20 mm cannons and four .50 cal Brownings, providing adequate lethality. US fighters standardized on Brownings, which had muzzle velocity of 885 m/s. German bomber-killer fighters used 30 mm guns, which needed 3 to 4 hits to down a heavy bomber but were inadequate against fighters due to low muzzle velocity of only 534 m/s, compared to 763 m/s for 20 mm installation on FW-190 and 860 m/s for 20 mm installation on British Spitfire.

First German night fighters did not have radar but proved as effective as radar-equipped British night fighters after ground control via broadcast commentary on bomber stream’s position, speed and heading was introduced in 1943. In same year, twin-engined fighters started receiveing radar. Main lessons of night combat were primacy of surprise, necessity to visually distinguish friend from foe (even if fighter needed to approach to as close as 60 meters), and necessity of using single-mission pilots.

In Korean War, F-80 was at disadvantage due to MiG-15s higher cruise speed; it could defeat bounce by MiG-15 if it saw it in time, but entrance of MiG-15 forced faster introduction of F-86 in theater. F-86 achieved 10:1 exchange rate over MiG-15 primarly because only small number of MiG-15 pilots – presumably Russian instructors – showed agressiveness and competence. Still, MiG-15s simple, reliable and sturdy construction meant that while more experienced US pilots easily got into position for a gun kill, F-86s .50 cal machine guns were unable to inflict enough damage to actually shoot down the aircraft, and 80% of kills achieved by F-86 were simply mission kills and not shootdowns; many MiG-15s were quickly back in combat after being “shot down”. One of main disadvantages of MiG-15 pilots, aside from being less trained, was that they were usually under close control. Airframe performance wise, MiG-15 had superior instanteneous turn rate but tendency to spin at higher angles of attack limited its usefulness to average pilot. Lack of hydraulic controls meant that MiG-15 had lower roll and pitch rates than F-86, increasing time to transit from one maneuver to another, and its worse cockpit visibility meant that it was in danger of surprise bounce. While MiG-15 had heavier armament, lower muzzle velocities lead to reduced lethality, though effect was negligible compared to impact that skill of pilots caused.

One of causes of MiG-15’s losses was tendency to fly in large formations. US aircraft flew in smaller formations which entered combat zone separately, reducing possibility of detection. However, war has also shown that while small US formations achieved very favorable kill:loss ratios, in very large engagements kill:loss ratios went towards equality.

After the Korean War, guided missiles started making an appearance on fighters. But in eight Cold War conflicts in which missiles were used (data for ninth, Iran-Iraq war, is not avaliable), only four conflicts saw use of radar-guided missiles designed to achieve BVR kills. These were operations Rolling Thunder and Linebacker in Vietnam, Yom Kippur War and Bekaa Valley conflict.

In Vietnam, F-4 was at disadvantage against MiG-15 and MiG-21 as its large size and smoky engines prevented it from achieving surprise, and MiGs could launch a surprise attack without being identified or even seen due to the smaller size and less smoky engine, sometimes from maximum range of their missiles (which themselves were IR based). In fact, F-4 had kill/loss ratio of 1:3 early in the war and probably 1:1 overall (April 1982 study “Comparing the effectiveness of air-to-air fighters” by Pierre Sprey indicates 2:1 kill:loss ratio fo F-4, and Russian records indicate 103 F-4s shot down by MiG-21 in exchange for 53 MiG-21s lost. As 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). 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 far better dogfight training pilots were recieving late in the war, and thus points to overall parity in exchange rate. But performance of complex weapons was far from stellar. Out of 56 radar-guided missile kills achieved, 54 (96%) were initiated and scored within visual range. In total, there were 597 radar-guided missile shots, of which 61 were made beyond visual range. Total of 56 kills were achieved, of which 2 at beyond visual range – one of which was a friendly kill against unaware F-4. As a result, radar missile kill probability was 9% in the entire war, 3% total at BVR and 2% at best against a competent and aware opponent. Both BVR kills happened in 1971-1973 timeframe; in that time, there were 30 radar-guided missile kills from 276 shots for Pk of 10,9%, of which 2 kills from 28 shots at BVR, for Pk of 7%. Improvement in performance of missiles in that timeframe can be linked to improvement in training, a statistical fluctuation or a mistake in data avaliable to Col. Highby, as Sprey’s study indicates that no radar-guided missile achieved Pk above 10%, with AIM-7E2 achieving 8% Pk, similar to AIM-7D. It is also interesting to note that, despite OV-1B having radars capable of recording imaginery with radar, this capability was never used in the air combat to allow safe BVR IFF.

In 1973 Yom Kippur war radar guided missiles achieved 5 kills in 12 shots, for Pk of 41,7%. There was 1 possible BVR kill out of 4 BVR shots, for a Pk of 25%, according to Colonel Highby.

In both 1967 and 1973 wars, Israeli visual-range Mirage III fighters – a 1950s technology – achieved 20:1 or better exchange ratios against Arab MiG-21s, primarly due to better pilots but also small size and good agility – which made it preferred platform for Israeli pilots. Similarly, 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.

In 1982 Bekaa Valley conflict radar guided missiles achieved 12 kills in 23 shots for a Pk of 52,2%, with 1 BVR kill out of 5 shots, for a Pk of 20%. In the same year, British Harriers achieved 19 kills in 27 shots (Pk of 70%) with AIM-9 Sidewinder; most if not all launches were from rear against bomb-loaded aircraft with no rearward visibility.

While data for Iran-Iraq war is not avaliable, it should be noted that Iraqi pilots tended to avoid Iranian fighters which means that latter might not have had any opportunities for attack. In any case, Iraqis eventually won air supremacy without firing a single shot once lack of spares grounded Iranian air force. This opportunity Iraqis wasted, never organizing their air force for close support or interdiction missions, and Iraqi air force was a non-factor in the war.

In both Gulf wars, radar-guided missiles achieved comparably good kill probabilities, similar to that in Yom Kipput and Bekaa Valley wars. In Desert Storm, radar-guided missiles achieved 24 kills in 88 shots, for a Pk of 27%. There were between 5 and 16 BVR victories (wording is unclear), but without data on how many shots were made at BVR; whatever number of BVR shots was, it was less than 60. One of BVR kills required 5 shots for a Pk of 20%, and if really 59 BVR shots were made, then BVR Pk is between 8% and 27%. It is known that F-15Cs fired 12 Sidewinders for 8 kills (Pk of 67%) and 67 Sparrows for 23 kills (Pk of 34%), though most shots were made within visual range. Pk for both Sidewinders and Sparrows is almost exactly 4,5 times of Vietnam Pk. Performance of missiles was vastly improved by the fact that Iraqi pilots did not take evasive action once the radar lock occured (even when in visual range). When they did know they were about to be attacked – such as pilots of MiG-25s that illuminated USAF F-15Cs on January 5th 1999 – they were usually able to evade long-range missile shots (MiG-25s managed to evade 6 BVR missiles – 1 AIM-120, 3 AIM-7 and 2 AIM-54). Interesting to note is also that the multirole F-16 performed far worse than purely air-to-air F-15 in the Desert Storm, firing 36 Sidewinders for zero kills; while 20 launches were actually accidental, and F-16C is far cry from the original lightweight fighter, large portion of problem can be attributed to the fact that USAF considers F-16 a bomber, and F-16 pilots spend a lot of time training for AtG missions, unlike F-15 pilots. Supporting this is the fact that Naval/Marine F-18 and F-14, also used by “multirole” pilots, fired 21 Sparrow and 38 Sidewinders, scoring one kill with a Sparrow (Pk=4,8%) and two with Sidewinders (Pk=5,3%).

It can be clearly seen that Yom Kippur war was far closer to Vietnam war than to Gulf War I, and Bekaa Valley war was equally removed from both conflicts. Yet missile Pk in both conflicts was far closer to that of Gulf War I than that of Vietnam war. Further, performance of both Sidewinders and Sparrows in Gulf War I was almost exactly 4,5 times of their performance in Vietnam. As such, reason for this massive improvement cannot be sought in improved performance of radar-guided missiles. There is one important factor which correlates radar-guided missile performance: in Vietnam war, US pilots had advantage in training over North Vietnamese pilots, but NVAF pilots were still well-trained and competent, and used aircraft – such as MiG-19 – with comparably good situational awareness. Arab pilots in all wars mentioned had very little training, and what training was carried out was of low quality; their aircraft also had very bad situational awareness. Therefore it follows that it is these two factors which brought about improvement in BVR missile performance, and not any improvement in missiles themselves, and it is thus unwise to compromise fighter’s WVR performance and cost for sake of improved performance in radar-based BVR combat. Even though some Iraqi fighters did have radar, lack of out-of-cockpit visibility and passive sensors – such as radar warners and missile warners, as evidenced by interviews with F-15 pilots showing that Iraqi fighters failed to react to either lock on or missile launch, and attempted little to no maneuvering, either offensive or defensive – has proven deadly, confirming need for good coverage with passive sensors. In both Gulf wars, US dual-role/multirole aircraft were concentrated on ground attack missions while single-role air superiority fighters provided air superiority; this was in large part enabled by Iraqi failure to generate large number of sorties despite having over 750 aircraft. Iraq had no capability to attack AWACS. Even so, radar-guided missile performance may be suspect (and not only for Gulf War but for all wars after Vietnam): immediately after Yom Kippur war, US claimed that 1/3 of Israelis’ claimed 251 kills were due to the Sparrow; yet Israeli General Mordecai Hod stated that only one kill was achieved by it, and that radar-guided missile was essentially useless.

It is interesting to notice that in four Cold War conflicts, 69 of 73 kills were achieved within visual range. All four BVR kills achieved were specifically staged outside the main combat to avoid fratricide; even so, one of these was a friendly kill, with an F-4E being the victim. In total, BVR Pk was 6,6% (4 kills in 61 shots). As for radar-defeating stealth, both British and French have confirmed that B-2 and F-117 are visible to ground radars; reason they were invulnerable in Iraq was two-fold: first, Iraq had easily the most incompetent military on the planet; second, they both flew only at night, a far safer time than day.

While IR BVR missiles did not have any better record than radar-guided BVR missiles when it comes to ability to kill targets, they do eliminate most of drawbacks of radar-guided missiles such as requirement for fighter to use – or even have – radar; this was not case in Vietnam, which does suggest that modern IR BVR missiles might have kill probabilities somewhere between radar-guided BVR and IR WVR missiles. Also unlike Vietnam, modern fighters can use IRST for relatively reliable BVR IFF (though there are various definitions of “visual range”, I chose to use one where it is range at which a fighter aircraft is visible in clear weather without use of optical sensors. In practice, however, using optical sensors for visual IFF simply extends VID range, and what was once beyond visual range combat becomes within visual range combat, even though it is not dogfight; maybe it should be called “optical range”?). It is also typical in a war for fighters to randomly intermingle, which means that visual IFF is the only reliable IFF.

And WVR combat is far from being “Vietnam era relic”: in September 2001, 2 IDF/AF F-15s engaged 2 Syrian MiG-29s in a turning dogfight. This again shows that BVR combat is still not dominant form of air-to-air combat: fighter aircraft designed around radar-based BVR combat are necessarily more expensive and complex than dogfighters, yet so far an effective BVR engagement has required both incompetent enemy and numerical superiority.

As an end conclusion, all fighter aircraft that performed well against a competent opponent had several characteristics in common: a) relatively low cost, b) easy maintenance, c) small size and low weight, d) comparatively good aerodynamic performance, e) good situational awareness with passive sensors (primarly pilot’s own eye). That is, a simple and effective design. Performance against incompetent opponents (Arabs etc.) tends to hide any shortcomings in weapons performance, and indeed in both Gulf Wars expensive and cheap weapons have performed equally well. Moreover, all wars in history have shown that human factor is the dominant factor in weapons’ performance. Yet as cost and complexity of weapons increase, training becomes less realistic, leading to decrease in users’ skill, and completely reversing theoretical advantages of more complex weapons – even if more complex weapon is truly more capable in hands of a skilled user (an assumption that is far from certain), it becomes less capable because user is less well trained. But even when genuinely more capable and used by forces with adequate training, there is no evidence that using complex weapons as a counter to numbers actually works, and lot of evidence that it doesn’t.

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. In fact, United States have always relied on numerical superiority and pilot training to win; aircraft quality never played a large part.

Tests

In the 1965 Featherduster test, Air National Guard F-86Hs at first achieved superiority over F-100s, F-104s, F-105s, F-4s and F-5s. Even when opposing pilots developed counter-tactics, only F-5s came close to achieving 1:1 exchange ratio. In 1977 AIMVAL/ACEVAL tests, F-5s simulating MiG-21s fought against F-14s and F-15s, achieving close to 1:1 exchange ratio (slightly worse than 1:1 against F-15 and slightly better than 1:1 against F-14); later on, rules were tuned to favor BVR platforms, and F-14 achieved slightly better than 1:1 ratio, whereas F-15 achieved 2:1 exchange ratio. Differences between pilots were in both cases greater than between aircraft types. Exchange ratio approached parity as total number of aircraft in the air increased. Main advantage that F-86 and F-5 had over other fighters was their small size, allowing them to achieve surprise bounces. AIMVAL/ACEVAL tests have also shown that pilots replaced in the F-5 were up to the full proficiency in two or three weeks, compared to the F-15 pilots who were still learning after three months, and that F-15s were more reliant on centralized control. But even if scores achieved after rules were tuned against the F-5 are used, F-5 is still strategically wiser choice: F-15A costs 43 million USD and can fly 1 sortie per day per aircraft, or 23 sorties per day for 1 billion procurement dollars; F-5E costs 26 million USD and can fly 3 sorties per day per aircraft, or 114 sorties per day for 1 billion procurement dollars. This means almost a 5:1 numerical advantage, against 2:1 kill:loss ratio disadvantage. F-15C, being 3 times as expensive as F-15A, faces almost 15:1 numerical disadvantage. F-16A faces “only” 3:1 numerical disadvantage, F-16C faces 7:1 numerical disadvantage, and F-22A faces 60:1 numerical disadvantage against F-5E.

Similarly, in exercises, US Air National Guard pilots have always performed better than USAF pilots despite using hand-me-down equipment up until receiveing F-16. This was because ANG pilots were better trained than USAF ones.

Applying the lessons learned

“Those who cannot learn from history are doomed to repeat it.”

George Santayana

All the lessons discussed above can be summed up by Clausewitz’s statement: “Everything in war is very simple, but simplest thing is difficult. Difficulties accumulate and end by producing a kind of friction that is inconceivable unless one is experienced war.” Complex weapons and processes tend to have more friction; thus they should be eliminated, as stated by WW2 saying: “Keep it simple, stupid.” Main lesson is that human factor is by far the most important factor determining performance of a weapon; bad fighter with a good pilot is far more worth than good fighter and an average pilot; but increased complexity works in human mind and makes operations more difficult. While centralization is detrimental for weapons’ performance in war, more complex weapons require more centralization – as evidenced by the US reliance on AWACS to enable BVR combat in both Gulf Wars, and F-15s heavier reliance on centralized control compared to F-5s in AIMVAL/ACEVAL.

Modern equivalent of German WW2 bomber-destroyer fighters are heavy radar-based BVR fighters such as F-22, F-15 and Su-27, which indeed are primarly useful as bomber interceptors. But air superiority fighter has completely different requirements.

First is the ability to outnumber the opponent. While entering combat with formation larger than enemy’s is a disadvantage for a superior aircraft, large number of small formations have advantage over small number of small formations, as well as over small number of large formations. Larger numbers also allow attacks on opponent’s support systems, such as tankers and AWACS, as well as coverage of one’s own vulnerable assets – be it CAS aircraft or support systems – at the same time. It should be noted that what matters is number of aircraft in the air: 2:1 advantge in fighters procured is actual parity if fighters fly half as often as opponent’s. In order to lower cost, FLX will use already existing technology where possible.

Due to importance of pilot training, and its impact on all points but first one, aircraft (from now on FLX) will have to be very reliable and cheap to fly, so as to facilitate as many hours spent for realistic dogfight training as possible (realistic meaning outside simulators, with performance of computerized weapons being calculated based on their actual combat performance).

To achieve surprise bounces, FLX will have low IR and visual signatures; also, sensors suite will be all-passive due to catastrophic effects of active sensors on achieving surprise (even if radar signal is not immediately detected, any radar is detectable once it locks on; and even RWRs on old Tornadoes can detect LPI radars). This means that no radar will be carried, except possibly for gun firing solution if surprise attack by using optical gunsight fails, and that missile warners will be IR based. Aircraft will be comparably small, no larger than Gripen A from front, thus giving it very small visual signature. Additional consequence will be low IR signature, which will be improved by adding an external cooling channel to the engine; exhaust of cool air from that channel will surround hot engine exhaust and help hide it from long-range IR sensors. Both BVR and WVR missiles will use passive IR seekers; this is especially important for BVR missiles as they require surprise to be effective, though even a miss can be tactically beneficial assuming that BVR IFF works – and only reliable IFF is optical one, either by Mk.I eyeball or by optical sensor such as IRST, as evidenced by numerous friendly fire incidents in Vietnam (1 of 2 BVR kills was friendly fire incident) and in both Gulf wars. As such, good passive sensors are a must.

In order to avoid being suprised, it will have complete spherical awareness through passive IR sensors, and will not carry any active sensors; deleting radar will also save ~150 kg in weight. Radar warners will also provide spherical coverage and will be capable of providing targeting solutions to attack targets well beyond targets’ own radar range, discouraging use of radar to attack the fighter. Cockpit will also be designed to provide good situational awareness, including good rearward visibility. Equally important in avoiding surprise bounces is a high cruise speed; maximum speed comparision is useless as it can only be achieved for a very short time in a combat zone, no more than few minutes. Minimum cruise speed required is M 0,9, but supersonic cruise of Mach 1,2 or above is desireable. To achieve supersonic cruise, one must have high thrust-to-drag ratio even in dry power; tailless delta-wing aircraft have advantage in this regime due to lack of detrimental interaction between wing and tail.

To maximize lethality of armament, gun will be 27 mm BK-27 revolver cannon. FLX will also carry IR missiles, but no radar-guided missiles as they destroy surprise and cannot achieve kills quickly. Long-range IR missiles may be employed to try and kill unaware opponent at BVR if possible; if BVR identification through IRST is not possible or surprise fails, it will be used to force the enemy to evade the missile and thus put himself into unfavorable starting position in a dogfight.

Lethality of weapons carried is expressed in number of on-board kills. Weapons load should provide enough ammo for several kills, as fuel fraction is sized to provide enough persistence for several engagements. Probability of kill will be taken as 0,3 for gun, 0,15 for WVR IR missile and 0,08 for BVR missile against competent opponent; against incompetent opponent, probabilities of kill are as much as 4 times as large as those noted. Gun will hold 234 rounds; at rate of fire of 28 rps and 0,05 s to achieve full rate of fire, it will fire 13 rounds weighting 3,38 kg in first half of second, and ammo will be enough for 18 0,5 second bursts, allowing 5,4 kills, or 8 1-second bursts for 2,4 kills. With 6 WVR missiles total number of on-board kills will be 6,3 or 3,3; if 2 WVR and 4 BVR missiles are taken, there will be 6,02 or 3,02 onboard kills, and if only 2 WVR missiles are carried, number of onboard kills will be 5,7 or 2,7.

Weapons also have to be resistant to enemy countermeasures; here, gun scores the best, followed by IR missiles. Primary countermeasure to gun is maneuver to defeat a firing solution. Missiles can also be defeated by hard maneuvers, but there are other countermeasures as well. Earlier IR missiles were vulnerable to be decoyed by flares. Missiles with imaging IR seeker are not vulnerable to it, but may be vulnerable to DIRCM. Also, most missiles still use radar-based proximity fuze (including IRIS-T and MICA-IR); this fuze can be jammed, preventing missile from detonating at proper time. Radar missiles are also vulnerable to fuze jamming, as well as jamming their radar signal and defensive maneuvers designed to break radar lock or simply evade them; this plus the fact that they destroy surprise mean that they won’t be used.

If surprise fails, fighter will have to outmaneuver the enemy. During dogfight, weapons must be fired quickly to avoid attack from unseen opponent; this means that radar-guided missiles are out of picture as they warn the enemy and are slow to lock even onto a cooperative target. Maneuvering performance itself can be divided into: a) acceleration/decelleration; b) transitioning from one maneuver to another; c) instanteneous g; d) outlasting the enemy in terms of fuel.

In order to maximize maneuvering performance, FLX will be small, light and will use delta-wing configuration with close coupled canards. This will allow low drag in level flight and turn, as well as low inertia, allowing for quick transient between two maneuvers; usage of delta wing will allow for low wing loading, allowing for good instantaneous turn rate, as well as low span loading which influences sustained turn rate. Pilot seat will be tilted back 30 degrees; while prone position would allow far better g tolerance, it would also create problems with rearward visibility. Shock from LERX will lower drag and thus allow for even better acceleration compared to Gripen C than just thrust-to-weight ratio would suggest; in fact, it will be able to outaccelerate any modern fighter aircraft. Engine will be turbofan with low bypass ratio and low temperature, improving performance, reliability and cost; increased thrust will require large air intakes, which will be used for more optimized canard placement. Wing will have added dihedral, thus reducing canard anhedral required for optimum vertical separation between canard tip and wing and improving roll rate (large wingspan harms roll rate but is required for low wing loading; dihedral added to the wing helps roll rate, as does reduction in canard anhedral). Low weight will be achieved by deleting the radar and increasing percentage of composites.

Outlasting the enemy will be achieved in three ways: having a high fuel fraction, having a low drag during turning engagements by achieving equal or superior turn rate at lower angle of attack when compared to the opponent and having a powerful engine. Wing loading (or more precisely lift-to-weight ratio) has impact on drag, since aircraft with higher LWR does not need as high angle of attack for same turn rate; additions which improve lift, such as LERX and close-coupled canards are also useful in this regard. Close-coupled canards also reduce drag as smaller control surface deflections are required for same response by the aircraft when compared to identical configuration but without close-coupled canards. Lower drag will allow fighter to throttle back and keep outmaneuvering opponent while spending less fuel, thus increasing persistence even more than fuel fraction suggests, whereas higher fuel fraction allows fighter to outlast the opponent even if other characteristics (TWR and drag) are similar. “Go-home” range and loiter time of fighter are also highly sensitive to fuel fraction. While having a powerful engine might seem contradictory when it comes to reducing fuel expenditure, it is not so: afterburner uses fuel at rate several times higher than dry thrust, for maybe 50% increase in thrust. Thus fighter which can stay in dry power for duration of dogfight will usually outlast the opponent even if opponent has higher fuel fraction. Engine will be M88 variant due to its low fuel consumption and low IR signature.

Also important is specific energy rate of the aircraft, which is thrust minus drag over weight, multiplied by velocity. This obviously favors lightweight aircraft with high thrust-to-weight ratio. But while one usually wants to keep energy level high, in some situations – such as when evading the missile – one wants to bleed off energy quickly. Delta wing with close-coupled canard is ideal for this purpose, as presence of canard means that lower angle of attack required for comparable lift allows less drag, while delta wing can cause large amount of drag at higher angles of attack.

Since fighter aircraft spend most of the time on the ground, where they are vulnerable to attacks, it will have to be able to fly from grass fields and dirt strips, as well as to be easy enough to maintain and supply so that depot-level maintenance is only rarely required, and regular maintenance can be carried out in mentioned open-field/road bases.

But pilot training is the most important factor in aircraft performance. Since pilots require 30-45 sorties per month to reach the full potential, low fuel usage and easy maintenance are a must.

Design

Engine will be Snecma M88-2, which is 350 cm long, has diameter of 70 cm, weights 897 kg and has 7.711 kgf of thrust. Gun will be BK-27. For sensors, main sensor will be PIRATE IRST, with DDM-NG missile warners, radar warners and laser warners also being used. There will be no radar as it adds weight for a limited value. Air duct will be curved in order to hide engine face from radars, reducing RCS and allowing more time for RWRs to solve a firing solution.

Length: 11,17 m

Wing span: 7,4 m

Height: 2,53 m

Wing area: 21,9 m2

Empty weight: 3.058 kg

Fuel capacity: 2.394 kg internal, up to 3.000 kg external (2*1.000, 2*500), 757 kg conformal

Fuel fraction: 0,43

G limits:

standard operational: +9/-3

combat operational: +11/-3,2

override: +12/-3,2

structural: +16,65

Turn rates (est.):

33-36 deg/s instantaneous

25 deg/s sustained

300 deg/s roll

Powerplant: Snecma M88

Dry thrust: 50,04 kN (5.103 kgf)

Afterburning thrust: 75,62 kN (7.711 kgf)

Fuel consumption: 0,08 kg/N/h dry, 0,175 kg/N/h wet > 4.003 kg/h dry, 13.234 kg/h wet, 792 kg/h cruise (mach 0,7 – 833 kph)

Dimensions: 350 cm length, 70 cm diameter

Weapons:

1 BK-17 with 180 rounds

2 IRIS-T

4 MICA-IR

Weight:

6.168 kg air-to-air takeoff weight

4.971 kg with 6 AAMs and 50% fuel

4.523 kg with 2 AAM and 50% fuel

(180 27 mm rounds = 93 kg; 2xIRIS-T = 175 kg; 4xMICA IR = 448 kg)

9.626 kg maximum takeoff weight (11.500 kg theoretical maximum 1)

(3.058 kg airframe + 2.394 kg internal fuel + 3.000 kg external fuel + 757 kg conformal fuel tanks + 93 kg gun ammo + 224 kg 2 BVR missiles + ~100 kg pilot and equipment = 9.626 kg)

Wing loading:

282 kg/m2 at air-to-air takeoff weight

227 kg/m2 with 50% fuel + 6 AAM

207 kg/m2 with 50% fuel + 2 AAM

440 kg/m2 at MTOW

Thrust-to-weight ratio:

1,25 at air-to-air takeoff weight

1,55 with 50% fuel + 6 AAM

1,70 with 50% fuel + 2 AAM (1,043 at dry thrust)

0,8 at MTOW

Speed (in combat configuration):

Maximum dash: M 2

Supercruise: M 1,5

Supercruise with 2 EFTs: M 1,3

Endurance:

35 m 53 s supercruise on internal fuel

13 m 9 s afterburner on internal fuel

1 h 5 m 51 s supercruise with 2 EFTs

3 h 2 min subsonic cruise on internal fuel

7 h 45 min 59 s subsonic cruise with maximum fuel > 6.469 km ferry range

Combat radius:

549 km supercruise on internal fuel

874 km supercruise with 2 EFTs

1.259 km subsonic cruise on internal fuel

2.311 km subsonic cruise with 2 EFTs

Combat radius with 15 minute loiter time:

320 km supercruise on internal fuel

675 km supercruise with 2 EFTs (tanks kept)

1.155 km subsonic cruise on internal fuel

Takeoff distance: 400 m (est.)

Landing distance: 450 m (est.)

Sensors:

1 x PIRATE QWIP IRST

4 x DDM NG MAWS (2 on vertical tail fin, 2 on missile launch rails)

4 x interferometric RWR

Countermeasures:

DRFM jammers

chaff

flares

Unit flyaway cost: 24 million USD (5 million USD engine, 12 million USD sensors and countermeasures)

Operating cost per hour: 3.000 USD

Sorties per day: 3

Notes

Cost per kg is assumed to be same as Rafale C’s 7.853 USD/kg. This is a conservative estimate since FLX is a single-engined aircraft and has simpler avionics (no radar, for example) than Rafale; also, FLX does not use either radar-absorbent or radar-transparent materials. Weight is based on the larger Novi Avion and Dassault Rafale. 9.550 kg Rafale is 15,27 m long, has wing span of 10,8 m and is 5,34 m tall; 6.247 kg Novi Avion is 13,75 m long, has wing span of 8 m and is 4,87 m tall. Thus relative to Rafale, 61% as large Novi Avion weights 65% as much. If estimate is based on Novi Avion, FLX would weight 2.438 kg; if based on Rafale, it would weight 2.268 kg. For conservativism, Novi Avion – based weight of 2.353 kg will be increased by 30% to 3.059 kg. To note is also that Folland Gnat, 75% as large aircraft, weighted 2.175 kg, thus giving possible FLX’s weight as 2.900 kg. Sortie rate is based on the F-5.

Fuel tanks: 1 l = 1.000 cm3 = 0,803 kg of fuel

• body tank: 36*25*490 cm + 2*(52*22*280) cm = 1.080 l * 2
• forward tank: 90*30*5 cm = 13,5 l * 2
• centerline tank: 521*10*10 cm = 52,1 l
• inboard wing tank: 5*450*33 cm + 5*(450+400)/2*32 cm = 142 l * 2
• middle wing tank: 5*69*(283+393)/2 cm = 116,6 l * 2
• outboard wing tank: (276+64)/2*132*5 cm = 112,2 l * 2

Wing length: 304 cm upper surface width

Wing area (both wings):

13*294,3 cm + 31*294,3*2 + 121*288,3*2 + 447*285,3 = 218.923 cm2

M88 and M88 ECO have identical dimensions, which makes them completely interchangeable; however, increased thrust of M88 ECO is not necessary for revised design due to its lower weight compared to the original.

Naval fighter will be heavier (3.265 kg empty) due to differences (stronger tail hook, stronger landing gear, strenghtened electronics etc.). Its structural g limit will be identical to land-based fighter, resulting in +9/-3,2 g combat operational load. At 8.140 USD/kg, identical to the Rafale M, it will have unit flyaway cost of 27 million USD.

Comparision with modern fighters

FLX will offer a far superior force presence and effectiveness to any modern fighter. This can be seen from following:

Aircraft for 1 billion USD:

FLX: 41

F-16A / Gripen A: 33

Gripen C: 30

F-5E: 28

F-15A: 23

Viggen: 22

F-16C: 14

Rafale C: 13

Gripen E: 11

Typhoon: 7

F-15C: 7

F-35A: 5

F-22: 3

Sorties per day per billion procurement USD:

FLX: 123

Gripen A: 66

F-16A: 40

Gripen C: 60

F-5E: 84

F-15A: 23

Viggen: 22

F-16C: 17

Rafale C: 26

Gripen E: 22

Typhoon: 14

F-15C: 7

F-35A: 1,5

F-22: 1,5

Number of on-board shots:

FLX: 6 1-second gun bursts, 2 WVR, 4 BVR missiles (2,42 kills)

Gripen A: 4 1-second gun bursts, 2 WVR, 4 BVR missiles (1,82 kills)

F-16A: 4 1-second gun bursts, 2 WVR missiles (1,5 kills)

Gripen C: 4 1-second gun bursts, 2 WVR, 4 BVR missiles (1,82 kills)

F-5E: 11 1-second gun bursts, 4 WVR missiles (3,9 kills)

F-15A: 8 1-second gun bursts, 4 WVR, 4 BVR missiles (3,32 kills)

F-16C: 4 1-second gun bursts, 2 WVR, 4 BVR missiles (1,82 kills)

Rafale C: 3 1-second gun bursts, 8 BVR missiles (1,54 kills)

Gripen E: 4 1-second gun bursts, 2 WVR, 6 BVR missiles (1,98 kills)

Typhoon: 5 1-second gun bursts, 2 WVR, 6 BVR missiles (2,28 kills)

F-15C: 8 1-second gun bursts, 4 WVR, 4 BVR missiles (3,32 kills)

F-35A: 2 1-second gun bursts, 4 BVR missiles (0,92 kills)

F-22: 4 1-second gun bursts, 2 WVR, 6 BVR missiles (1,98 kills)

Number of kills possible per day per 1 billion procurement USD:

FLX: 297

Gripen A: 120

F-16A: 60

Gripen C: 109

F-5E: 328

F-15A: 76

F-16C: 30

Rafale C: 40

Gripen E: 43

Typhoon: 31

F-15C: 23

F-35A: 1

F-22: 1

Combat radius on internal fuel:
FLX: 549 km (supercruise), 1.259 km (subsonic cruise)

F-22: 671 km (supercruise), 1.284 km (subsonic cruise)

Rafale C: 1.250 km (subsonic cruise)

Typhoon: 1.100 km (subsonic cruise)

F-35A: 940 km

Harrier II Plus: 556 km

F-5E: 702 km

MiG-29: 700 km

Gripen C: 400 km

F-16C: 500 km

F-18: 1.060 km

F-15C: 1.100 km

Su-27: 1.200 km

Su-30: 1.500 km

Su-35: 1.800 km (subsonic cruise)

(when not explicitly noted, aircraft is incapable of supercruise and radius is given for subsonic cruise; when radius is noted as being for subsonic cruise, and supercruise radius is not noted, aircraft is capable of supercruise but I didn’t find any data on exact range)

Tactically, combination of supercruise, good endurance, completely passive sensor and weapons loadout (allowing among other things a fully passive BVR IFF and engagement capability), low IR and visual signatures and extreme agility make FLX far superior to all other fighter aircraft in existence, allowing it to achieve surprise against all fighters in the world except Dassault Rafale, and first detection against Rafale. It should be noted that Western supercruising fighters – F-22, Typhoon and Rafale – do not need afterburner to either achieve or maintain supersonic speed, though use of afterburner is preferred to reduce time spent in transonic regime to minimum. Thrust-to-weight ratio that is above 1 at dry thrust at dogfight weight will allow FLX to use afterburner very sparingly during dogfight, possibly not at all. This will, especially when combined with high fuel fraction, allow the FLX to outlast any fighter aircraft in the world when in combat.

Strategically, only aircraft that can outnumber the FLX are F-5 variants, excluding the F-5E. These, however, are at disadvantage due to limited range, owing to their low fuel fraction. In fact, FLX is in upper part of range estimates for modern fighter aircraft (only advanced Su-27 variants have significantly longer range than the FLX), thus thoroughly disproving the fallacious dogma that long range = large, expensive fighter. F-5 is also at disadvantage tactically because of its limited situational awareness and inferior maneuverability.

Further reading

Original article

CAS fighter proposal

FAC aircraft proposal

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