F-7PG Flight Trials

Gp Capt Kaiser Tufail and Wg Cdr Jamshed Khan were detailed to test fly the F-7MG (later known as F-7PG in PAF service) in July 1997.   A total of 12 sorties were planned in which the complete flight regime was to be explored, with particular focus on the improvements in performance of the already in-service F-7P (Chinese variant of the early model MiG-21F-13).  A similar number of sorties were to be flown after a few months, when the GEC-Marconi Super Skyranger radar was expected to be ready. PAF’s evaluation was the first by a prospective foreign customer, although the aircraft had accumulated almost 10,000 hours in the PLAAF since its induction in late 1995.

Soon after arrival in Chengdu, the wet tropical weather of Southern China made it quite obvious that the flight trials would take longer than expected.  Two other unusual challenges were the language barrier and the issue of finding enough airspace over non-populated areas.  Chengdu is one of China’s largest metropolitan centres and is located in Sichuan Province, which happens to have the country’s densest population per acre.  In such environments, supersonic flights as well as low-level max-speed trials left no room for area violation in the narrow sliver that had been allocated for flight trials. The pilots had also been told that their departure back home could be delayed in case the adjacent Chengdu International Airport was to lodge an air violation complaint. The hint was well registered!

Major Improvements

The F-7MG airframe has essentially the same F-7P fuselage, tailplane, fin, and inner wing sweepback of 57°.  The outer wing section incorporates the major change, with a reduced 42° sweepback and automatic leading edge manoeuvring flaps. The F-7MG is powered with an improved and more powerful WP-13 engine, which is also operational on the F-7III (Chinese variant of the MiG-21MF).  Additionally, cockpit layout, avionics and several ancillary systems have been changed, in line with modern trends.  The important systems that remain unchanged (compared to the F-7P) are the fuel system, weapons payload capacity and internal guns.

Double Delta Wings

Like the old Soviet Su-15, the Swedish J-35 Draken, as well as the more modern Rockwell/Deutsche Aerospace X-31 post-stall manoeuvring demonstrator, the F-7MG has a double-delta wing planform, which offers an excellent solution to a slender delta’s inherent low aspect ratio problem.  The aspect ratio of conventional deltas is, at best, of the order of about 2.4, with the low end notched up, surprisingly, by India’s Tejas. At 1.75 it stands behind the bat-winged double-delta Saab Draken, whose very low aspect ratio of 1.8 was considered to be a convenient remedy to the transonic Centre of Pressure (CP) shift, albeit at the expense of overall aerodynamic efficiency.  In contrast, the F-7MG has an aspect ratio of 2.8.

Wing tip stalling has never been an issue on the F-7P, but the double delta wing brings with it an added bonus in this respect.  The strong vortex of the inner wing re-energises the boundary layer of the outer wing, preventing span-wise flow towards the tips.  This allows even more-carefree manoeuvring at ultra-low speeds.

Testing the Wings

On the first take-off, it was evident that the aircraft was impatient to get off the ground and had to be held down to prevent it from getting airborne prematurely.  Compared to the F-7P’s take-off speed of 310 kph, the MG lifted off at 280 kph with ease and the advertised 35% improvement in take-off distance was on the mark.  The sight of the auto-manoeuvring flaps at work reminded the pilots of the F-16’s computer-controlled leading edge devices. Packaging the servo motors and actuators within the thin leading edge without the tell-tale bulges has certainly been a marvel of engineering at Chengdu Aircraft Corporation (CAC).

The feel of the aircraft was smooth in all domains, none more so than in transonic flight.  As expected, CP shift was minimal and both the test pilots were unanimous about the decrease in stick forces.  Transonic being an important combat flight regime, this is a welcome improvement.

A good measure of a wing’s lifting efficiency is at high angles to the incident airflow, as in tight turns or slow speeds.  What better than to pace the MG through a slow speed loop?  Normally, a safe entry speed for a loop on the F-7P would be between 800-900 kph (at 15,000 AMSL).  In the absence of any guidelines on a slower version of the manoeuvre, it was decided to try 700 kph at first.  The MG went through smoothly without any hint of judder or slip at the top.  With full faith in the leading edge flaps, the next loop was performed at 600 kph.  Again, the same results were achieved and the aircraft went through a perfect loop without any jitter or judder.  At lower altitudes it might have done even better, but airspace limitations at Chengdu did not permit low level aerobatics.

Several flights followed the first check of the aircraft’s aerodynamic efficiency.  It was a most pleasant surprise to note that the turn rates were nearer to the F-16 at medium to high altitudes, and were exactly as advertised.  A 33% improvement over the F-7P at 5,000’ AMSL, 50% at 10,000’ and 66% at 20,000’ would certainly call for an end to the “supersonic sports plane” sobriquet that dogged the F-7MG’s forerunners.

The results of the flight trials were so encouraging that the test pilots were tempted to simulate a flamed-out engine landing pattern, a not very done thing on delta-winged fighters.  While the Chinese manuals suggested a rectangular pattern that can put one’s judgement and nerves to test, the standard overhead spiral pattern was tried out initially from a high-key height of 15,000’ AGL.  With engine idling and speed brakes out to simulate a dead engine, the aircraft glided much like the F-16, so after a few approaches, the high-key height was lowered to 12,000’ AGL.  The sink rate was well under control, and in fact was so well manageable that all later sorties were terminated through practice dead-engine approaches.  At 1:8.5, the glide ratio compares favourably with some of the modern Western fighters.

Landings on the F-7MG could be made at 270 kph, compared to about 290 kph on the F-7P.  Both the test pilots felt that the speed could be lowered further, were it not for the length of the gear struts, which are not long enough to allow a higher nose attitude, and a consequent tail scrape.  Hydraulic brakes, though still hand-held (like those on a bicycle handle-bar), were very effective, and the unlimited braking facility was a welcome improvement over the somewhat restricted pneumatics of the F-7P.

New Engine

The WP-13F engine of the F-7MG produces 1,200 lbs more thrust than the F-7P’s  WP-7, giving it a thrust-to-weight ratio of about .9 compared to .8 of the latter in clean take-off configuration.  A 50% improvement in spool-up time was found to be a welcome feature, particularly on final approach and landing phases where a rapid go-around may be necessitated for any reason.  With a faster engine spool-up, a bad landing is actually a thing of the past on the MG. Use of titanium alloys in compressor blades and an increased Time Between Overhauls (TBO) are indicators of improvements in Chinese jet-engine technology.

The thrust increase was evidenced by a 25% improvement in acceleration time from 500 kph to 1100 kph and an equally impressive time-to-climb to 36,000’ AMSL. All improvements were verified and were found to be as advertised or even better.  Even more remarkable was the fact that these trials took place in hot and humid weather, well outside the 15°C, 1013 hP environments in which the specifications are usually ‘engineered’ by the manufacturer.

Miscellaneous Systems

Used to advanced cockpits of the F-16, both test pilots were quick to point out several ergonomic improvements and had detailed discussions with CAC design bureau.  Switchology changes and relocation of several instruments led to a much improved cockpit. These changes include a Stores Management System, which is a useful cockpit-pilot interface to help establish the status of stores including configuration, fusing and weapon codes, etc. A voice warning system, colour video recorder, elaborate cockpit lighting and a more precise and jitter–free Angle Of Attack (AOA) probe are nice-to-have improvements.  The colour Electronic Flight Instrument System (EFIS) includes two displays, one for the attitude indicator and the other for the heading and navigation sub-systems like ADF, VOR, TACAN, ILS etc.

Radar

The F-7MG was originally designed to have the GEC-Marconi Super Skyranger.  At the time of initial PAF trials the radar was not ready.  Trials were held again several months later after the prototype radar was installed.  In the event the radar did not come up to PAF specifications and GEC-Marconi was not able to surmount the problems associated with the small nose cone, including antenna size and equipment air-conditioning which was insufficient.

The PAF eventually retrofitted their F-7Ps and F-7PGs with the FIAR Grifo-7.  To say that miniaturisation technology is at its best in this marvellous Italian radar would be an understatement.  With an excellent pulse Doppler radar having respectable ranges and a medium order azimuth and elevation scan, the system is married to the all-aspect AIM-9L Sidewinder missiles, making it a lethal combination.

FT-7PG

CAC did not design a dual-seat version of the F-7MG.  On PAF’s request, the existing FT-7P cockpit was redesigned on lines of the PG to ensure standardisation and the resultant dual seater was re-designated FT-7PG.

Brief Analysis

The F-7MG has considerably improved subsonic and transonic flight performance.  Coupled with excellent turning capability and acceleration, the combat potential is enhanced tremendously.  The Grifo-7/AIM-9L combination on board PAF’s F-7PG brings the aircraft closer to the F-16 in close combat capabilities, and the PAF must be credited with extracting the maximum from an innovatively redesigned low-cost fighter.

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IAF's Balakot Disaster Two Years On

As with any political party in power, the Indian elections of 2019 were critical for Bharatya Janata Party (BJP), for it wanted a stronger showing than its previous term in power. The issues of rising unemployment, currency demonetisation, farmers’ complaints of low remunerative prices, and not the least, the persistent insurgency in Kashmir had, however, dented BJP’s prospects considerably. Something needed to be done to avert a poor show at the hustings. Pakistan, perceived as India’s perennial nemesis, was the perfect scapegoat which could be accused of supporting the uprising in Muslim-majority Kashmir. BJP assessed that targeting Pakistan on charges of supporting terror in Kashmir would be fully supported by both sides of the political divide in India. According to the Pew Research Centre, their 2018 and 2019 surveys suggested that the significant majority of the Indian voters considered Pakistan as a “very serious threat” to their country, and terrorism to be a “very big problem.”

On 14 February 2019, a Kashmiri youngster carried out a suicide attack by ramming his car into a police vehicle, killing 40 troops of Central Police Reserve Force. The attack was in retaliation for the excesses committed by para-military forces, which had tortured and maimed hundreds of young men, and raped scores of women in a relentless campaign of terror. Instead of reflecting on the causes of the on-going insurgency, the Modi government found it opportune to blame Pakistan yet one more time.  Without an iota of evidence to present to UN or any other world adjudication body regarding involvement of Pakistan in the attack, the Indian government decided to exact revenge on its own. With elections just six weeks away, the timing could not have been more favourable for Prime Minister Modi.

IAF struck a purported terrorist training camp at Jabba, near Balakot town early morning on 26 February. Fortuitously for Pakistan, the brazen attack started with a string of failures, which continued embarrassingly throughout the operation. Of the planned package of twelve Mirage 2000H which were to strike, two aborted on the ground, while four had to abort in the air due to cloudy weather which precluded use of the electro-optically delivered ‘Crystal Maze’ bombs. The remaining six Mirages delivered their ‘Spice 2000’ bombs from a stand-off range of 40 km; five bombs exploded on a hillside, well away from the target, which was actually a seminary that housed teenage children learning to memorise the Holy Quran. There was no loss of any life or property.

IAF stood guard on the night of 26 February when PAF’s riposte was expected. Extensive Combat Air Patrols (CAP) were flown by IAF, with surveillance support from ground radars, as well as an AEWCS aircraft anchored over Adampur.   When PAF did not show up till sunrise of 27 February, IAF eased off from its highest alert state, and waited for the following night.  A pair of Su-30MKI was patrolling near Srinagar, while a pair of Mirage 2000I was patrolling east of Udhampur.   PAF’s deception worked splendidly when its strike package of four Mirage 5PA/IIIDA and two JF-17, duly supported by a big swarm of escorts and patrolling fighters (a mix of F-16A/B and JF-17), cluttered the scopes of IAF’s ground radars at 0920 hours. Working at the rear of the fighter package were PAF’s SAAB Erieye AEWC aircraft, and the DA-20 Falcon in which electronic warfare wizards sat ready with their arcane tricks.

Two vintage – but still quite capable – Mirage 5PA, each armed with one H-4 stand-off  bomb, along with two JF-17, each armed with two Mk-83 Range Extension Kit (REK) bombs, headed towards their respective targets in southern-western Indian-Held Kashmir (IHK).  Each Mirage 5PA was followed by its communication control aircraft, a dual-seat Mirage IIIDA, which was to steer the H-4 after launch through data link, while the JF-17s’ Mk-83 REK were to be launched in the autonomous ‘fire and forget’ mode. Since the purpose of the mission was essentially to demonstrate that Pakistan had the resolve, as well as the capability of responding in kind, it was decided that there was no compelling need to pick the front door of a brigade commander’s office, or the air shafts of soldiers’ bunkers. General area bombing of open spaces in military garrisons near the Line of Control (LOC) in IHK was, therefore, agreed upon.  It was expected that this ‘abundance of restraint’ would prevent mass carnage in the Indian military garrisons, which could otherwise lead to a chain of escalatory actions, and spiral into a very dangerous all-out war under a nuclear overhang.  When PAF struck the garrisons within 32 hours of IAF’s abortive air strike at Balakot, it came like a ‘shot across the bow’ and had the desired sobering effect on the Indian military commanders.  

Meanwhile, the pair of patrolling Su-30s were completely shocked when they were targeted by an F-16 with an AIM-120 missile at long range. Narrowly surviving an apparent proximity hit, both Su-30s scampered out of the area, leaving the field to the Mirage 2000 pair. When the IAF ground radar sought to position the Mirages to tackle the F-16s, both terror-stricken Mirage pilots expediently declared fire-control system malfunctions, and also bowed out without a fight. The desperate ground radar control then scrambled two pairs of MiG-21 Bison to tackle the rampaging PAF fighters. It was not long before an F-16 fired an AIM-120 missile at one of the Bisons that was charging in headlong, rather recklessly. The Bison was promptly blown out of the skies; its pilot, Wg Cdr Abhinandan, was lucky to parachute to safety, and was promptly apprehended by Pak Army soldiers inside Pakistani territory.

While air combat was in progress in the skies, an IAF combat search and rescue Mi-17 helicopter holding in the combat zone was shot down with a Spyder SAM, as the Terminal Air Defence Unit radar at Srinagar took it for a Pakistani UAV. The costly mistake resulted in six aircrew fatalities. For the IAF, it seemed like a morning of endless misfortunes.

India had the initiative, and could also exploit the element of secrecy and surprise to its advantage. However,  these possible benefits were squandered by the IAF as the operation was flawed in its planning, and entirely disastrous in its execution. Some of the basic planning considerations were flouted: cloudy weather resulted in cancellation of the electro-optical weapons delivery, elevation data fed into the autonomous Spice 2000 bombs was in error, capabilities of the PAF’s BVR air-to-air missiles were not well-known to IAF aircrew, and the determination as well as the state of readiness of PAF was taken lightly.  More serious was the failure of IAF’s patrolling fighters to pick up the gauntlet when challenged, allowing PAF fighters to have a free run; it reflected poorly on the morale and training of IAF pilots. Oversight of the operation was faulty at all levels of command, and cannot be put down to bad luck by an air force that claims to be professional.

It is a wonder that despite such a fruitless operation, the Indian media painted it as a great victory. Fabrications knew no bounds when an F-16 was claimed to have been downed by Abhinandan. The Indian pilot had truthfully claimed on TV – while sipping a ‘fantastic’ cup of Pakistani tea – that he was still searching for the target on his radar when he got zapped by an air-launched missile. Apparently, the Bollywood habituated Indian public least bothers about fact-checking, and two years down, continues to revel in the ‘great victory,’ despite a most discomfiting rout. It must be confessed, however, that media manipulation was the only success of Modi’s government.

The reaction of the international community to India’s brazen aggression against Pakistan was muted, and outright condemnation was absent. The closest any country got to disapproval was a neither here nor there statement, calling 'all parties to exercise restraint.' In an environment where freedom movements are labelled as terror campaigns – as in Indian occupied Kashmir and Palestine – it is not difficult for the host governments to justify punitive action against suspected supporters.  Pakistan needs to be wary of this reprehensible trend, and needs to be at the diplomatic forefront to quell hostile propaganda by its adversaries, especially India.

Though the failed IAF strike did not bring any concrete dividends, it did open up the possibility for India to repeat such action in future. The mistakes made in planning and execution of 26/27 February 2019 operation are certain to have been remedied, and it would be naïve to believe that India is not raring for a revenge bout. India has never digested the fact that its military options against Pakistan have been limited by the latter’s nuclear capability. To keep an upper hand as a regional player, India is likely to resort to periodic muscle-flexing through so-called ‘surgical strikes.’ These could be conducted with stand-off weapons launched by conventional fighters, or more likely by Unmanned Combat Aerial Vehicles (UCAV), which may be the new norm in Indo-Pak conflicts. Pakistani military, especially the quick-reacting PAF, needs to maintain its operational readiness at the cutting edge to deter India from any adventurism in future.

© KAISER TUFAIL

This article was published (under a different heading) in Pakistan Politico, February 2021 issue.

Impact of Rafale Induction in IAF

Quite clearly, the inadequacy of IAF’s Su-30MKI and MiG-29 twin-engine fighters in the air superiority role led to the decision to acquire the Rafale, ostensibly a more modern and capable multi-role fighter. While both Russian fighters are highly manoeuvreable in a visual dogfight, as evidenced in several IAF exercises with RAF Typhoons and USAF F-15s, they seem to have shortcomings in network-centric, Beyond Visual Range (BVR) combat. This was noticed during the 27 February 2019 skirmish with PAF F-16s, when a pair of Su-30s failed to establish data link and were of no mutual support to each other. The capabilities of the much-touted N011M ‘Bars’ airborne intercept radar are also suspect as the patrolling Su-30s were unable to launch even a single radar-guided R-77 BVR missiles against two dozen PAF fighters milling in the area on 27 February. While a definitive conclusion about the shortcomings of the Su-30 fire-control radar and missiles cannot be made on the basis of a single engagement, it is clear that they were not at par with the PAF F-16/AMRAAM combo.  IAF was aware of these limitations of the Russian fighters, which is why it had initiated measures for the acquisition of Western multi-role combat aircraft instead of more Su-30s, as far back as 2012.

IAF’s choice fell on the French Rafale, which is, indeed, a formidable multi-role fighter with long range and endurance, along with a sizeable payload in the class of the Su-30, areas that single-engine fighters like the F-16A/B and JF-17 cannot compete in. One bare metal Rafale comes at a cost of $120 million apiece, while one with a worthwhile armament suite and full logistic support costs twice as much.  Dollar for dollar, PAF can acquire three JF-17 Blk-III for the cost of one Rafale, thus more than offsetting the latter’s payload capabilities, at least. The range of the Rafale’s Meteor missile claimed by the manufacturer (MBDA) to be 200 km led the Indian Prime Minister to ruefully state that, “if we had the Rafale, results would have been different [on 27 February].” Mr Modi has apparently not yet been briefed by his Air Staff about the JF-17’s  PL-15 BVR missile guided by the new AESA radar, which beats the Rafale’s ramjet-powered Meteor by several tens of kilometres.[1]  In an interview with Flight Global magazine Commander of USAF Air Combat Command, General Herbert Carlisle stressed that he regarded outmatching the Chinese PL-15 air-to-air missile as "exceedingly high priority" for the US. "The PL-15 and the range of that missile, we've got to be able to out-stick that missile," Carlisle underscored. It is manifest that with missiles like the PL-15 and Meteor, long range BVR combat will take precedence over close combat in any future conflict.

While we are at it, it may be worthwhile to have a cursory line comparison of the Rafale, F-16A and JF-17 in one-on-one visual air combat. All three aircraft have a ‘clean’ configuration Thrust-to-Weight Ratio of 1:1 and can climb and accelerate equally well.  In a turning fight, Aspect Ratio and Wing Loading are critical parameters. The JF-17 and F-16A enjoy better Aspect Ratios of 3.7 each, compared to the Rafale which stands at 2.6. A better Aspect Ratio (square of wing span to wing area) implies better aerodynamic efficiency due to less induced drag during turning.  As for Wing Loading, or the weight of the aircraft per unit area, the lesser the better.  The Rafale has a slight edge, having 68 lbs/sq ft compared to the JF-17 and F-16A, both of which have Wing Loadings of 77 lbs/sq ft.  A lightly loaded wing helps in a tighter turn, though in case of the Rafale, this advantage is overcome by greater induced drag due its lower Aspect Ratio. In sum, all three fighters are alike, more or less, in a turning fight.

Induction of the Rafale in IAF has created considerable media interest, and the impression has been created that with immediate effect, IAF will rule the Indian skies. It must, however, be remembered that it will be some years before the Rafale achieves anything close to Full Operational Capability[2]. PAF, on the other hand, has been flying F-16s for four decades, including hot scenarios during the Afghan War, in local counter-insurgency operations, and the latest Operation ‘Swift Retort,’ downing half a dozen enemy fighters in these operations.  The JF-17 has been fully operational for over a decade, and is expected to replace the legacy fighters over the next five years. These combat-proven PAF fighters are fully integrated with the air defence system, and are mutually data-linked, alongside all AEW and ground sensors. Such capabilities are not achieved overnight, and it will be several years before the Rafales can be considered a threat in any real sense. Any immediate impact of the Rafale on IAF’s air power capabilities is, thus, simply overhyped.  This inference, however, must not be dealt with lightly, as there is a distinct possibility of the Indian Prime Minister using the Rafale for a false-flag operation in a surreptitious manner, to prove his point that, “with the Rafale, the results would have been different,” from those of 27 February 2019.

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[1] Some sources providing details of PL-15 maximum range:

https://www.iiss.org/publications/the-military-balance/the-military-balance-2018/mb2018-01-essays-1

https://www.globalsecurity.org/military/world/china/pl-15.htm

https://militarywatchmagazine.com/article/pakistan-s-pl-15-missile-equipped-jf-17-block-3-is-a-serious-game-changer-how-india-can-respond-to-regain-superiority

https://warontherocks.com/2018/02/not-fathers-plaaf-chinas-push-develop-domestic-air-air-missiles/

[2] For a minimum 1:1 pilot-cockpit ratio, 42 pilots need to be trained for 30 single-seat and 6 dual-seat Rafales.  If two training courses of 10 pilots each are run per year, it is likely to take at least two years for these aircraft to be fielded in full strength.

Picture credit: Kristof Jonckheere (www.airliners.net)

© KAISER TUFAIL

This article was published in Pakistan Politico, September 2020 issue.

Fighters of Indo-Pak Wars

A fighter is a flying machine designed to shoot down enemy aircraft, besides performing many other ground attack roles. Depending on the threat to be countered, the operating environment and the weapons available, capabilities of a fighter vary widely.  Trade-offs are made in several areas, the more prominent ones being performance and manoeuvrability.  Each fighter is, therefore, a compromise, but with certain qualities emphasised in order to best fulfil the primary task for which it has been designed.

Aircraft Performance includes parameters like rate of climb, ceiling, acceleration and speed which play a significant part in the interception of an adversary; the latter two parameters can also help in rapidly extricating out of a thorny situation.  As would be expected, unbeatable aircraft performance is dependent on good design, and availability of excess energy.  Thrust produced by the engine can be a convenient index of available energy; however, when an aircraft is considered as a mass acting under the force of gravity, a simple reading of engine thrust values can be misleading.  ‘Thrust-to-Weight (T-W) ratio’ is the factor that helps appraise aircraft performance in a correct perspective.  Besides enhancing basic performance parameters, a high T-W ratio also helps sustain turn rates by countering the effects of drag induced during manoeuvring flight. 

Higher thrust is, of course, produced by paying the penalty of higher fuel consumption.  Sufficient on-board fuel quantity can thus be seen as an important factor if aircraft performance is to be fully exploited.  ‘Fuel fraction’ is a term used to denote the internal fuel as a fraction of aircraft weight in the clean configuration.  It gives an idea of the staying power in a dogfight, assuming that fuel consumption rates of different turbojet engines are largely similar.   A fuel fraction of less than .25 for afterburning turbojet fighters and .20 for non-afterburning ones is considered inadequate.

            

Manoeuvrability, or the ability to out-turn an opponent, is an important attribute of a fighter.  Turning is measured both in terms of radius of turn as well as rate of turn.  A good radius of turn is a ‘nice to have’ feature, but an attacker rarely needs to turn as tightly as his adversary to maintain a favourable position in a stern attack, unless at very close ranges. A defender, on the other hand, needs to swing his tail away from an attacker’s flight path as fast as possible by generating a high rate of turn.  Thus in a turning fight, rate of turn is of greater significance than radius of turn.

Turning ability is dependent on wing design, and the easiest understood feature is ‘wing loading’ or the weight of the aircraft per unit area of the wing (which is the source of most of the aircraft lift).  During a turn, when banked flight tilts the lift vector away from the normal, and drag wrecks whatever remains of the angled lift, a low wing loading comes in handy to help balance the essential lift-weight equation.  Low wing loading is thus advantageous to an aircraft turning for a smaller radius, as well as a higher rate of turn, at any given speed.  At very low speeds, however, when an aircraft is on the verge of stalling, devices like slats and flaps preserve/generate much needed lift; in such speed regimes low wing loading does not help matters much.  

Creating lift in an aircraft incurs an unavoidable penalty in the form of induced drag.  Aerodynamic efficiency is achieved by designing a wing that produces maximum lift for the least drag.  This is done by having a high ‘aspect ratio,’ which is the ratio of the square of the wingspan to the wing area. Since induced drag happens to be inversely proportional to the aspect ratio, greater the wingspan, lower the induced drag.  A high aspect ratio is thus an important factor in combat, as it helps in sustaining turn rates.  A good combination for manoeuvrability would, thus, be low wing loading for enhanced turning ability, along with a high aspect ratio to help sustain it.  (High aspect ratio also improves endurance and ceiling, and shortens take-off/landing distances.) 

As fighters become faster, their aspect ratios have to be reduced to minimise supersonic wave drag.  This is done by presenting a smaller frontal area to the supersonic airflow with the help of a smaller wingspan, besides other profile streamlining techniques.  It can thus be seen that the conflicting requirements of high-speed pursuit flight and subsonic manoeuvring flight have a bearing on the aspect ratio, and compromises invariably result. 

Fighters of Indo-Pak Wars include some of the classics of jet age.  The Sabre, Starfighter, Gnat and Hunter had earned reknown in the Indo-Pak sub-continent due to the 1965 War. The later MiGs and Mirages are no less celebrated, if for no other reason than their large production numbers, and service in numerous air forces.  Fighter pilots who have flown these aircraft would swear that theirs was the best fighter ever, with facts and figures to back up their claims.  With due regard to their opinions, here is a brief description of these fighters on the basis of some well recognised criteria. 

The F-6 was a Chinese copy of the MiG-19, the first supersonic fighter of the Soviet bloc. It sported highly swept-back wings which, at 55 degrees, were considered the right antidote to drag rise during transonic flight.  Thick wings were the answer to the  low lift generating ability of highly swept wings, but drag rise due to the stubby profile did not help matters. Despite two powerful afterburning turbojet engines which helped in initial acceleration, it could barely keep pace with subsonic fighters at low altitude.  Low wing loading coupled with a high aspect ratio gave it excellent dogfighting abilities, though a poor fuel fraction limited its staying power in a dogfight. A pair of AIM-9B Sidewinder missiles along with a set of three powerful 30-mm cannon were lethal weapons to finish off an aerial target. The same cannon armed with armour-piercing bullets, along with two rocket launchers having 8x57-mm rockets each, served a useful close air support role. 

Though of Korean War vintage, the F-86F Sabre continued to soldier on in many air forces, due largely to laurels earned during that conflict.  It was a good fighter from the point of view of manoeuvrability, as the low wing loading and high aspect ratio would suggest.  Its low T-W ratio however was no help in preventing speed from bleeding off in sustained combat.  Paradoxically, this was an advantage that turned the tables on many an opponent because of the Sabre’s superb low speed handling, thanks to a fine slatted wing.  An excellent all-round view from the bubble canopy was a delight for the Sabre pilots.  The Sabre’s six 0.5" guns with a total of 1,800 rounds provided enough firing time to target several aircraft, as was demonstrated twice in the 1965 War. The Canadair CL-13 Sabre Mk-6 (designated F-86E in the PAF, not to be confused with the regular North American Aviation ‘E’ model) was better endowed than the ‘F’ model in terms of T-W ratio, due to a more powerful engine. 

The F-104A Starfighter’s high T-W ratio coupled with a streamlined supersonic design, positively impacted acceleration, maximum speed and rate of climb. Due to its sleek profile and fantastic pursuit performance, it came to be known as a 'manned missile.' A good fuel fraction ensured that it could maintain its high performance long enough. As far as manoeuvrability is concerned, the Starfighter was an utter disappointment due to the very high wing loading and low aspect ratio.  Armed with a Gatling gun firing 66 rounds a second, along with AIM-9B Sidewinder missiles, the Starfighter generated enough awe if not a high turn rate, to keep its adversaries at bay!

The Mirage IIIE is a derivative of the earlier ‘C’ model, which was the first Mach 2 fighter from the Dassault stable. It came to be the progenitor of a very successful series of multi-role fighters that continue to operate well past their fifth decade since the prototype flight. The Mirage IIIE has a very low wing loading that is helpful in instantaneous turns, but an unimpressive T-W ratio robs it of the ability to keep up in a dogfight. A very poor aspect ratio (typical of delta wing planforms) causes phenomenal drag rise in manoeuvring flight, which is only worsened by the lack of a tailplane, since the upgoing elevons on the wings deduct considerably from overall lift. Prolonging a dogfight is thus, sure to be disastrous.  Its Sidewinder missiles, hard hitting 30-mm cannon, and an airframe customised for high speed are the saving grace in a hit-and-run fight. The aptly named Mirage can easily go supersonic at low altitude, and twice over at high altitude.

‘Jew’s Harp’ would not be a misplaced moniker for the diminutive Gnat, which vied for a place amongst an ensemble of more daunting fighters. A fine blend of performance and manoeuvrability, it had a relatively high T-W ratio for a subsonic fighter, giving it good acceleration, while its low wing loading and relatively higher aspect ratio conferred it with an impressive turning ability.  Due to its small size, the Gnat surprised its opponents on many an occasion when it was sighted too late. This attribute especially, made it a formidable fighter in air combat.  The Gnat’s size was, however, also a liability in so far as it did not permit large external loads, and restricted it to the role of a 'guns-only' point defence interceptor.  Propensity of its 30-mm cannon to jam was a sore point with pilots, as was claimed to have happened in combat on more than one occasion.  The Gnat had a reasonably good fuel fraction, which at first sight would appear quite unlikely. 

India’s first indigenously built jet fighter, the HF-24 Marut went through serious teething troubles which it failed to outgrow. What might otherwise have been a first class fighter, it essentially failed to find a potent powerplant. Poorly endowed with a pair of very low T-W ratio engines, the HF-24 was useless as an air combat fighter. It was however put to limited use for ground attack, in which role its four powerful 30-mm cannon packed a powerful punch.

The Hunter F-56 was an outstanding fighter in all respects. Though outdone by the Sabre in manoeuvrability by a slight margin,  it made up with its higher speed and better acceleration. Like the HF-24, its four 30-mm cannon provided it with tremendous firepower against aerial, as well as ground targets.

The MiG-21FL had an uncomplicated 'tailed delta' design, and was easy to fly even to the limits. It was more manoeuvrable than its bisonic counterpart, the F-104A, but not in the class of its subsonic contemporaries whose low wing loadings in particular, were unmatchable.  The MiG’s low aspect ratio caused high drag rise during turns, though a good T-W ratio offset this limitation to quite an extent. Its K-13 missile, despite employment restrictions, did instill caution in the minds of adversary pilots; the 23-mm cannon, however, had low lethality as well as a very short firing time.

The Mystère IVA was a reasonably good fighter, though not as manoeuvrable as the Sabre. It lacked the latter's wing slats, and could not turn as well, especially at low speeds. Except for a few odd aerial engagements, including a daring duel with an F-104 in the 1965 War, it did not figure significantly in the fighter role.

With wings swept back at an audacious 62 degrees, the Su-7BMK looked every bit a high-speed fighter-interceptor. However, its heavily loaded wings were no good for manoeuvrability. Due to a high T-W ratio, it could rapidly accelerate away, provided it had not run out of three afterburner light-up chances that were available, which was a serious handicap in combat. With a poor fuel fraction, staying in afterburner for long was not a viable prospect anyway. Though endowed with two hard hitting 30-mm cannon, it could not carry IR missiles, and was best employed as a ground attack fighter with up to four rocket launchers having 16x57-mm rockets each, as its primary ordnance. Its robust structure earned it the reputation of being unbreakable, as was demonstrated in several safe recoveries despite serious battle damage.

The aging Vampire FB-52 was not really a match for the PAF fighters.  Its aluminium and balsa wood structure gave it a very light wing loading, but its poor T-W ratio and unimpressive maximum speed were grave liabilities, due to which it was relegated to a second-line role.

Note: Aircraft profiles not to scale.

         

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> Colour profiles of aircraft, courtesy Tom Cooper.
> PAF aircraft data obtained from respective Pilot's Flight Manual.
> IAF aircraft data obtained from Encyclopedia of World Air Power, edited by Bill Gunston; Hamlyn/Aerospace Publishing Ltd, London, 1981.

© KAISER TUFAIL

PAF's Quest for Self-Sufficiency

The Pakistan Aeronautical Complex (PAC) started off as an overhaul factory for the Chinese F-6 fighter, with the first aircraft rolling out in 1979.  Several more factories were added over the years, resulting in today’s vast complex at Kamra in northern Pakistan.  PAC is a state-owned enterprise with the goal of self-reliance and indigenization in the field of military aviation. PAC is governed by a Board headed by the Chairman who is a serving Air Marshal of PAF.  The PAC Board is overseen by the Ministry of Defence Production.  PAC deals with two main aeronautical engineering activities: i) production of military aircraft, and ii) maintenance, repair, and overhaul (MRO) of military aircraft, engines, and ground-based radars.

Aircraft production takes place at the Aircraft Manufacturing Factory (AMF), the military aircraft production unit of Pakistan Aeronautical Complex.  The factory was conceived for the licensed manufacture of the SAAB-Scania MFI-17 primary trainer aircraft, after sufficient experience was gained in assembling 92 of these from knocked-down kits.  The new factory was inaugurated at Kamra in 1981, and in September 1983, it produced the first MFI-17, locally named Mushshak (Proficient).  By end 1997, AMF had manufactured 180 Mushshak aircraft from raw materials for PAF, Pakistan Army, and overseas customers.  In July 1996, the upgraded Super Mushshak featuring a more powerful engine, an air conditioned cockpit, electrical trimmers, and a digital glass cockpit, flew for the first time.  In due course, all PAF Mushshaks were upgraded at AMF.  By June 2018, 60 all-new Super Mushshaks had also been manufactured for overseas customers including air forces of Azerbaijan, Nigeria, Qatar, Oman and Saudi Arabia.  Production continues apace for an increasing number of  orders, which includes a major one from Turkey.

Pakistan and China signed an agreement for design and development of an advanced jet trainer in 1986, on a 25:75 cost-sharing basis.  The prototype K-8 flew in 1990, and PAF acquired the first batch of six aircraft in 1994. Satisfied with its performance, PAF signed successive contracts for 34 more aircraft. A total of 16% of the airframe including the horizontal stabiliser, vertical tail and engine cowling was produced at AMF, with final assembly taking place at Hongdu Aviation Industry, Nanchang. The K-8 trainer has been exported to several countries, with PAC manufacturing a total of 50 sets of the afore-mentioned sub-assemblies.

In 1995, Pakistan and China signed an MOU for joint design and development of a new fighter.  In 1999, a contract for co-production of the JF-17 was signed between China National Aero-Technology Import & Export Corporation (CATIC) and PAC.  Soon AMF began manufacturing various components, and by 2008 production of sub-assemblies had started, which made up 58% of the airframe (wings, horizontal stabilizer and vertical tail). The remaining 42% of the airframe (fuselage) is manufactured at Chengdu Aircraft Corporation, with final assembly of the aircraft taking place at AMF. As of December 2018, 112 aircraft had been manufactured at AMF. Work continues apace for an additional PAF order of 76 aircraft under the current fiscal outlay.  With the capacity of AMF to produce up to 24 JF-17s a year, ongoing export orders are also being accommodated alongside PAF’s requirements.

In 2007, Pakistan became the launch customer of Falco UAV made by Selex, Italy, when it purchased eight knocked-down kits for assembly. Later, PAC signed a contract with Selex for manufacture of the UAVs.  So far, 20 units have been manufactured by AMF.

MRO tasks are undertaken at three factories. The Mirage Rebuild Factory (MRF) overhauls Mirage III/5 fighter aircraft and its Atar 9C engine.  Several engines of Western origin including Pratt & Whitney F-100-220 of F-16A/B, Allison T-56 of C-130E, Honeywell TFE-731 of K-8, and Continental J-69 of T-37 are also overhauled at MRF.  The Aircraft Rebuild Factory (ARF) overhauls JF-17 and F-7P/PG fighter aircraft, K-8 jet trainer, and Y-12 commuter aircraft, along with overhaul of C-130 propellers; ARF also has several facilities that manufacture aircraft canopies, drop tanks, and electrical harnesses.  The Avionics Production Factory (APF) overhauls ground-based radars, in addition to licensed production of the Italian Grifo 7 radar of F-7P/PG, and assembly of KLJ-7 radar of JF-17.  APF also undertakes production of an assortment of avionics items including radar warning receivers, IFF, crash recorders, navigation systems, MFDs, and PCBs.

© KAISER TUFAIL

This article was published in Defence Journal, June 2020 issue.

PAF's Transnational Exposure

PAF has had the unique opportunity of training pilots of many air forces in the Middle East and Africa.  PAF pilots have flown on trainers and fighters in Algeria, Egypt, Iraq, Jordan, Kuwait, Libya, Qatar, Saudi Arabia, Sri Lanka, Syria, Turkey, UAE, UK, and Zimbabwe.  The pilots gained extensive experience on an assortment of fighters including F-5A, F-5E, Lightning, MiG-17, Mirage F-1E, Gnat, Hunter, MiG-21FL/M, and Su-7; the latter four types were of particular significance to PAF, as these were flown by its traditional adversary, IAF. First-hand knowledge about adversary aircraft, as well as well-honed flying skills of PAF’s pilots were key factors in their remarkable performance during various conflicts.

During the 1967 Arab-Israeli War, PAF’s expert marksman Flt Lt Saiful-Azam, who was on deputation to Jordan, downed an Israeli Mystère IVA while flying a Hunter.  A day later, he shifted to an Iraqi air base and shot down an Israeli Vautour IIA and a Mirage IIICJ.  A near-ace, he had earlier shot down an Indian Gnat in the 1965 war.

In 1974, during a combat air patrol in Syria, Flt Lt Abdus Sattar Alvi, part of an all-PAF eight-ship MiG-21 formation, claimed an Israeli Mirage IIICJ, bringing some cheer to the beleaguered Syrian Arab Air Force.

PAF has also been a regular participant in various multi-national exercises with China, Saudi Arabia, Turkey, UAE, UK, and USA.  Pilots have enthusiastically fought against A-6, F-4, F-14, F-111 and Hunters of yesteryears, as well as the modern fighters including F-15, F-16, F-18, J-10, J-11 (Su-27 copy), Mirage 2000, Tornado, and Typhoon.   Operations in electronically jammed environments, flying in large strike packages at very low altitudes, and air combat against fighters with AEWC support, are some of the scenarios PAF pilots have been exposed to, during these exercises.

© KAISER TUFAIL