Fighter pilots who know say that single engine fighters being smaller are better optimised aerodynamically improving their survivability in a dogfight

The generally believed superior survivability of a twin-engine fighter is also questioned

by Mohan Guruswamy

The Indian Air Force has just released an RFI (request for information) for 110 fighters not very much after the Narendra Modi government scrapped the MMRCA deal for 126 fighters to buy 18 ready for combat Rafale fighters and 108 to be built in India. The French Rafale was chosen as the fighter for the future after an almost decade-long process of contemplation, examination, evaluation and a competition that came to be called the “shoot-out”. We still haven’t got to know why it really was scrapped?

The IAF was hoping for a minimum of four squadrons of Rafale fighters, but the Narendra Modi government has kept the initial order down to 36 fighters in a flyaway condition for 7.8 billion euros or $9.13 billion (@1 euro=$1.17). Commenting on this, the officer who headed the intensive selection process that led to the choice of the Rafale, Air Marshal (retd.) M. Matheswaran observed that “the original MMRCA tender was cleared for $10.5 billion for 126 aircraft,” suggesting that delay in deciding is also a factor that is costing the country dear.

The Rafale is a twin engine, canard delta wing, multi-role fighter designed and built by Dassault Avions to replace a multitude of specialised platforms such as the Jaguar, Mirage F-1, Mirage 2000 and Super Etendard. To that extent it is truly a multi-role aircraft, but is still very different from what it was initially intended to originally replace — the Mirage 2000.

The single engine Mirage 2000 was designed as a competitor to the USA’s F-16 and made an impressive debut at the Farnborough air show in 1978. In 1985, in response to Pakistan’s acquisition of F-16 fighters, the Rajiv Gandhi government decided to induct 150 Mirage 2000 fighters into the IAF. The first 49 aircraft were to be imported from France and the rest manufactured by HAL. But the second part of the program was not implemented despite HAL having invested in an assembly line for Mirage 2000’s. What happened is still a matter of speculation.

But there is another scandal implicit in how a bid by the IAF to buy more single engine Mirage 2000 fighters became a bid for the heavy MMRCA. But the MoD turned this IAF request down opining that the Mirage 2000-5 variant being offered by Dassault was a different aircraft because it was not the Mirage 2000. The dash 5 suffix was enough for the mandarins to decide it was a different aircraft and hence a fresh bid should be called for. This is how the requirement for a light fighter became a competition between twin-engine fighters. Now we are back at square one. The IAF still wants light fighters to replace its large but obsolete fleet of single engine light fighters like the MiG 21, 23 and 27 series.

The arguments over the pros and cons of single and twin-engine fighters are old. One perennial argument is that two engines make the aircraft less vulnerable, give it more range and weapons load.

Fighter pilots who know say that single engine fighters being smaller are better optimised aerodynamically improving their survivability in a dogfight. They argue, “having one engine means that mass is distributed closer to the central axis which reduces roll inertia and improves roll onset rate”. Their smaller size also means that they are more difficult to acquire by hostile radar or visually. These experts also argue that single engine fighters tend to have superior fuel fractions, which is the weight of the fuel divided by the gross takeoff weight of the aircraft. A lower fuel fraction means a comparable or longer range. Besides all modern fighters, light or heavy, are now equipped with aerial refueling

The generally believed superior survivability of a twin-engine fighter is also questioned. Most modern twin-engine fighters have their engines next to each other and the loss of one in combat or due to fire often means the other also doesn’t make it. These experts also cite numbers to bolster their claim. Their data shows that the USAF loses more twin jet F-15s to engine fires than the single engine F-16. Also the F-18 Hornet’s crash rate is 3.6 per 100,000 hours, while the Gripen’s is 2.46. Others challenge the survivability argument citing Gulf War data analysis showing the F-16 had a loss rate of 0.22 per 1,000 sorties while the F-15s had a loss rate of 0.91 and F-18’s a loss rate of 0.66.

The proponents of twin-engine fighters usually weigh in with the IAF’s experience with the MiG-21. The MiG-21 was designed in 1954 and has some basic design flaws such a cockpit visibility and high landing speed (360 kmph). Almost half the MiG-21 crashes were due to pilot error due to inadequate training facilities such as AJT’s and simulators. To compound problems the quality of manufacture and spares by HAL has been very suspect. In any case, the MiG-21 series are well past their use till age. The IAF literally flies them held together with wire and soap. That’s why they should be retired to parks and playgrounds as soon as possible.

Finally there is the cost factor. According to open sources a JAS 39 Gripen can cost anywhere between $30-60 million each depending on configuration. By contrast a Rafale starts at $80 million.

According to the website, the Gripen can outcompete the Eurofighter on costs and in a number of key areas such as better range, higher speed, less weight and lower operating costs. A former Air Chief estimates a price difference of anywhere between `250-350 crores each between a 4 gen single and twin-engine fighters.

The IAF has been shouting itself hoarse over the rapidly depleting fleet. The MoD’s insistence on a complete new process, like the almost decade long MMRCA process, is seen as another ploy by the bureaucrats to delay the process. It makes even less sense when the IAF and MoD have the information needed to make an enlightened and perhaps even honest decision. But the question still remains; why not restrict this bid to single engine fighters, particularly since the total costs will be much less? Besides the only two single engine fighters to choose from now are the Saab JAS 39 Gripen and the Lockheed F-16C Block 72 Viper have already been evaluated in the course of the MMRCA shoot out. Both manufacturers have expressed their willingness to break ground in India and build factories to aggregate the aircraft here.

The promise of the Tejas LCA has so far remained a promise. Even if the Tejas-Mk2 is finally cleared for serial production, HAL cannot produce them in the numbers and time frame the IAF requires. Clearly we need two production lines of single engine light fighters, one of who must almost certainly be the Tejas. In the years to come, as India’s economy grows and as regional Geo-politics will inevitably change, India will have to consider a bigger air force and hence cost will become a more important factor. Unlike the Marut HF24, the Tejas should become the building block for a truly indigenous fighter aircraft design and production capacity. That’s why, apart from the huge economic benefits, “Make in India” becomes so important. Without it we are just like another Saudi Arabia splurging on military hardware.