History, Old wives tales, TEDBF and the NLCA

                                                        .

Prof. Prodyut Das

 

September 27, 2025

 

There has been talk of having a common fighter for the IN and the IAF. The advantages of a common platform are obvious but if you dip into those aspects of aircraft design neglected (unfortunately!) in India- history, common sense, superstition, back of the envelope calculations and old wives tales, perhaps the enthusiasm for the obvious solution may dampen. What I put down here is not a challenge to the views held by the proponents of a common airframe for the IAF and IN but as a sort of grist to the discussion’s mill that the precedents for the idea of a common platform are not encouraging.

Past experiences with the Common platform

To me it seems that in advocating the TEDBF as a common platform we are perhaps trying to do something that has been attempted many times before but never be done well. People will throw the Phantom II at my face but whilst I will be the first to repeat Alexander Yakovlev’s praise that technically the Phantom was a triumph for US Aerospace Industry, its less lovable characteristics were due to its naval origins. There were two, connected, “defects” in the Phantom’s layout. One, a somewhat undersized wing, comes from the Naval carrier environment i.e. a wind over deck- in the Temperate zone of up to 30 knots - and the urge of a catapult launch. Naval aircraft often have wings smaller than would have been ideal for land base operations eg aircraft like the Buccaneer in South Africa and the Jaguar (remember there was a M version also) in India come to mind. They worked well enough on temperate lands and seas but when used from land bases the aircraft missed the urge of the catapult and the “wind over deck “effect”. In general flying too there was just that sense of being a tad underpowered and a tad under-winged. The other fault of the Phantom was specific to the type- the long engines of the era dictated a sharply upswept rear fuselage, possibly to avoid tail strikes during landing. This resulted in the stabilizer being located in the perfect wrong position during high AOA operations. Thin “sharp” LE, “small” highly swept wings, high wing loadings and a stabilizer deep in the turbulence of a “near stall” wing at high AoA- is it any wonder that if in a spin and below 10,000 feet the drill for the Phantom was to eject. I have given you the naughty gossip but the fact is if you try to have a common platform for the AF and the Navy you will do aerodynamic injustice to one or the other. Given the design skills of our present set up there is a considerable probability of injustice to both customers, I being cautious by nature and pessimistic about ADA then or now.

Americans attempts confirm the above problem

The Phantom was not the only example. In the early 1960s the US tried to solve the problems encountered in “the Common platform” by smothering it in technology. In it’s now infamous TFX programme- the Flying Edsel- which emerged as the F 111 A/B/…Z avatars they thought VG would take care of all the problems and there were even dreams in Western Publications that the F 111 would take on MiG 21s. I think the whole F 111 idea was so ridiculous only the A model came into service but again, being well engineered if not well conceived, in the usual American way, it excelled in the role of an intruder, doing more expensively what could have been done much more effectively by the less glamourous Intruder. I note with relish that for their next generation fighters, they had distinctly separate platforms. The F 16 and the F 15 for the Air Force and the F 14 swing wing and F 18 Hornet for the Navy. Note separate platforms for separate services. One would have thought that the Americans had learnt their lessons but one is dealing with Americans; they went back to the fatal attractions of a common platform for the JSF program in the F 35 A/B/C. We know what happened. For once it seems even the Americans have bitten off more than they can chew! Oh! The F 35 probably works but it is not air power! The F 35 is the aeronautical equivalent of the French General’s cry “C’est magnifique mais c’est ne pas de Guerre!” at Balaclava. Given the above and conceding the advantages of a common platform should we not learn from the past?

 

As of the moment ADA’s ability to design and develop platforms is nothing much to be writing home about- and that is being polite. A common new platform for the AF and the N by even a seasoned design team will be like seeing a dog walking on its hind legs- it has be done- but rarely has it been done well. For India I would humbly say lay off for the present, we don’t have the US funds, experience, honesty and dynamism, what with simple fourth generation programme running for 40 plus years and no end quite in sight and a new hitch or excuse as soon as we solve the current one. Until we fine comb what went wrong with the Tejas management we will waste time.

 

It would be better to develop two dedicated platforms using common systems and aggregates. ADA apart , the others in the business have developed platforms within reasonable times and costs.  With re- organization, good project monitoring and breaking down old silos, it would be possible to develop good separate platforms withing 3 to 5 years. To the cautions of History about the fate of “common platforms” for IAF/IN idea we must add a second “common sense” caution. We don’t have the Carrier for the TEDBF, nor any decision about its specifications which will be inputs for the design of the TEDBF- speed, size, lift dimensions and CATOBAR or Ski ramp. The last CV took us from 2009-2022 to build. This one is still sailing in the Raisina boat club! The question then becomes what do we do?

 

What does History whisper? An aircraft that can operate from a small carrier will work out of a bigger carrier also so why not work with what we have? How much miniaturization can we do? In the early 1950s the USN asked for proposals for a new attack aeroplane for the yet to be launched “Super Carrier” The Carriers were to be of the 100,000-ton displacement and the MTO of the requested attack aircraft was, IFIRC. i.e about 20 plus tons. Several companies responded.  When the request for proposals came to Ed Heinmann of Douglas, he realised that possibly the chance of the Congress sanctioning the behemoth CVs were slim and he set about seeing if the requirement could be met by an aircraft that could be operated by from the existing carriers. Common sense.

 

Carrier’s launch speed. lift and catapult immediately set constraints on wing span, length and MTOW so he, like the Dalai Lama, set about breaking the rules of conventional concepts gently. He knew that the pure delta is, except for niche applications, a pretty hopeless planform but he chose it not so much for aerodynamics as for weight savings, compactness and because it gave the maximum wing area in a fixed span ~ he could avoid having wing folding, which he reckoned would cost him about 110kg in weight in hinges, piping, jacks etc. In the same pursuit of weight savings, he avoided the usual cutouts in the wing torsion box skins for the wheels to retract in. The small span meant, I heard tell, he could avoid having to use the tapered rolled sheets for the skins and used standard sheet and extruded bulb sections to save materials and manufacturing costs. He used three spars giving considerable battle damage resistance and the central spar acting as an anti- slosh baffle for the fuel; he used the inside of the wing as one huge fuel tank tip to tip and he just added only another self -sealing fuel tank in the fuselage for the “get home” fuel, saving further weigh in the additional piping,  valves and brackets multiple tanks would need. The wing being one piece tip to tip, the load transfer to the fuselage was only in shear which small brackets could carry avoiding heavy carry over structures which had to tackle both shear and moment loads. The shape of the aircraft was decided, one could say, not just by aerodynamics but by structural weight considerations also. That was just the wing! Now imagine that kind of attention to detail in every system and every nook and cranny. The end result of quiet good engineering housekeeping was that finally the Douglas Skyhawk came out doing what the USN thought to be the job of a 50,000 lbs MTOW aeroplane for an MTOW of only 22,000 lb. Some 2960 were built and served with distinction both as a shipboard and a ground-based aircraft (e.g., Israel, Singapore) for over 60 years.

 

The Skyhawk illustrates that quite remarkable improvements can be made by maturity, job knowledge, honesty and quiet patience, so perhaps instead of chasing the ideal TEDBF we may quietly re- look at what we can do with the Tejas. The present Tejas has not been designed to the Skyhawks levels of maturity and thus has considerable scope of benefitting by re- engineering. However, the Skyhawk was a tailed delta – possibly the world’s first and the NLCA is a tailless delta. We have a Tejas NLCA weighing 8700 kgs empty (I cite a Delhi Defence Review report AFAIK). The Navy has done a commendable job of testing such a overweight aircraft on a carrier but it is operationally useless. What can we do in this situation? Two questions immediately arise in the mind viz. can a tailless delta be safely operated from a carrier and if so what is the precedent, extensiveness of that experience and the size of the carrier and ii) how much weight can we expect to reduce on the “as is” NLCA?

 

History gives us some crunchable numbers.  

 

The answer to the first is that ED Heinmann had himself designed tailless delta in the early 1950s for Carrier operations and they had been successful and popular in US service e.g. the Dougla Skyray F4 D popularly known as the Ford. About 482 were built and its carrier qualifications trials were done on the 27,000 tons, 271 mts., catapult equipped carrier USS Ticonderoga- something much smaller than our carriers but note the “Ti” had a catapult. The Skyray, popular with its pilots held the world speed record and the time to height records in the mid-fifties. This was an aircraft without FBW and the USN had a much better opinion of the aircraft than the other tailless aircraft, the Chance Vought Cutlass but to be fair the Cutlass’s bad reputation as a “widow maker” was more due to being underpowered rather than being of the wrong configuration. So the well-designed tailless delta can be considered as “a proven in service” concept. I have used F4 Ds handling related parameters i.e. span loading, wing loading, T/W and compared it with the NLCA. The results and the commentary are placed at Table1.

 

The NLCA is badly overweight reportedly, because the design team did not know the landing load parameters for design of the undercarriage of carrier borne aircraft. The story (if true) goes that the USN “tricked” ADA about the details but what prevented ADA from having the wit to first “back calculate” from the Sea Hawk data is not known or discussed! 

 

To estimate what should be a reasonable empty weight one again has to go back to History. One has to choose a Carrier borne tailless supersonic aircraft- something of the rarest of a rara avis. To be fair I could not use the F4D weight and dimensions figures to arrive at the revised target weight of the lightened NLCA because the F4D was a transonic aircraft, and adding supersonic capability pushes up weight and dimensions by about 35% so it would be unfair on the Tejas to compare weights with the transonic F4D. Fortunately, Ed. Heinmann was sufficiently satisfied with the F4D configuration to repeat it for the F4D replacement, the F5D and that had a confirmed top speed of M 1,6 and thus we are comparing -one tailless supersonic fighter with another tailless supersonic fighter- apple to apples.

 

To arrive at the estimate of weight the dimensions of the two aircraft were compared and to compensate for the considerable differences in engine technology in the 30 years between the J 57 (F 5D) and the F 404 (NLCA) appropriate adjustments were made. We use the F 5D to set up a target weight for the NLCA. However, the F 5 D did not enter service for political reasons and thus did not see extensive service so we use the data of the F4 D which saw extensive service to compare the desirable parameter of handling.

 

Table 1 Comparing dimensions and weights of F5D and NLCA variants

 

All figures in MKS units

 

Sl.No	Aircraft	Span	Length	Ht.	Wing area	A,R	Empty wt.	Engine wt.
1	F5D	10,21	16.4	4.51	51.74	2,01	7913	2347
2	NLCA (2009)	8.2	13,2	4.4	40	1.68	8800	1042
3	NLCA 414 (Lightened Re-designed)as is proposed	8.2	13.2	4,4	40	1.68	5700	1242
	Column No	1	2	3	4		5	6

 

 

The much larger F 5. D of similar configuration, all metal construction and an engine 1300 kgs heavier and “valve “avionics” is lighter than the smaller, largely composites NLCA with modern solid-state avionics and FBW controls. Shocking it may be but it is also an indication of how much can be improved by a competent team.

 Another 3 tons or so can come off the present NLCA’s empty weight bringing it to around 5700 kilos which will allow the carriage of a weapons load which is currently zero. All my other similar comparisons return the empty weight figure of the Tejas to be in the 5500 kgs region. The T in TEDBF?  The reliability of modern engines is such that two engines of the TEDBF is not justified except in terms of installed thrust. A re- engineered NLCA may be more useful a venture than a brand new TEDBF with brand new uncertainties.

 

The table indicates that a NLCA lightened to a weight of 5500 kgs, possibly with a F 414 engine will be a useful aircraft- something like a Skyhawk in its utility. It would be an ideal re- engineering project between the Navy and one of the contenders being invited to take part in the AMCA etc projects. Apart from lightening the structure the aspect ratio of the wing has to be tweaked- it is too low to be flown by inexperienced pilots. Since the Delta is pretty insensitive to changes tweaking the AR will not be a major redesign but will benefit docility of handling considerably.

 

Table 2. A comparison of handling related parameters between the NLCA as at present and when lightened and fitted with F 404 or F414 engines. The F 4D is used as a marker of what was used in the field and had worked in active service. All units in appropriate MKS system .

 

Sl,No	Aircraft	Empty Weight	MTO	Wing Loading	Span Loading	Power Loading	Aspect ratio
1	F4 D	7268	12701	240	1200	0,57	2.0
2	NLCA (T)	8800	11000	285	1300	0.7	1.7
3	NLCA F404	5400	13500	360	1600	0.574	1.7
4	NLCA  4I4	5700	13500	360	1600	0.715	1.7

 

The table is self- explanatory. SL no:

1.      is the handling related parameters of the F4D at MTOW launch weight. This is used as a datum of the parameters required for carrier operations, the caution being to remember that the F4D’s carrier had a catapult.

2.      is the launch weight of the NLCA trialled by IN with ski jump. The higher wing and span loadings may have been compensated by the higher T/W. The higher T/W came from the aircraft not carrying any war load.

3.      the figures are for a revised weight improved airframe carrying a MTOW of 13,500. The higher wing, span and power loadings are to be noted and are to be offset against the fact that the NLCA can carry full internal fuel and about 3 tons of war load. Note the wing, span and T/W loadings are inferior to the NLCA trialled by the Navy.

4.      Finally, is the same airframe fitted with the heavier F 414 engine and carrying the same war load as 3. Perhaps this would be the best bet.

 

The possibilities of improving the Tejas is endless as many mistakes have been made. Correcting them would be a therapy and a foundation. Given the pace of change in war air warfare to launch into a new venture such as TEDBF will only add to the mess.