AJEET Development

By PM Velankar .”velu”

As Anandeep Pannu says it was excellent recap on Ajeet development by Wg Cdr J Thomas . Being a first hand account it is of immense value ! Even if it is , as he says ” involved only on the periphery. ”

I was lucky to have flown Gnat as well as Ajeet . Unfortunately all the 31 odd hours I flew on the Ajeet were Flight Test sorties . These 31 odd hours were spread over a period of almost 7 years between 1977 and 1984 . 19 odd hours in 1977 – 78 on post production aircraft at HAL and the remaining 12 odd hours between 1979 – 84 on storage aircraft at Sulur . The flying was very thinly spread out , about 4 odd hours in a year . As all sorties were Flight Test sorties , never did any tactical , formation , armament work, High or Low Level navs or any “squadron flying ” , I am therefore not in a position to comment on steinemenns remark that “the Ajeet range performance was disappointing” .

My first sortie on Ajeet was a post production Flight Test sortie in HAL . I will not go in to the details of changes in various test parameters , between the Gnat & the Ajeet . I will rather give couple of things which made lasting impression on me during that first sortie .

After start up and switching ON of the R/T , what took me by surprise was the total SILENCE . Even the hum of running engine was not audible ! I blew in the mike but did not hear any thing . Called up “testing 123 ” etc , same silence ! Pressed the PTT and again said ” testing 123 ” , this time I heard myself and so did every one else listening on that R/T channel because the next thing I hear was Bangalore ATC saying ” aircraft giving test call we read you strength 5 , please give your call sign .” Thus I made my first discovery which left a lasting impression . It was that ” The feed from the mike to the ear phones was completed only when the PTT was pressed ” . In Ajeet one could not hear himself speak unless PTT was pressed . That being my first sortie on Ajeet , I was briefed on air test , but this particular aspect did not figure in the briefing .

In all the aircraft I had flown till then , the moment R/T was switched on all the sound inputs of the mike were fed to the earphones and the pilot could hear himself talk .Every pilot , particularly a fighter pilot speaks to the aircraft and himself to get that extra bit from the aircraft or from himself . I do not think there is even a single fighter pilot who has not cursed , shouted or egged himself on and on in a combat sortie . These verbal urgings and hearing yourself cursing loud and clear , almost always extracted that additional couple of “g”s or tightened the turn by that little bit more . Cajoling and coaxing the aircraft in low speed scissoring or in a dicey situation always worked and the aircraft did respond at speeds 05 Kts 10 Kts lower than to what you had operated in the earlier sortie ! I consider this a most desirable characteristic in an aircraft . Even the engine humming and the noise of rush of the air around the aircraft has always been good auditory input for a pilot .In fact I felt that in case of engine flame out , the loss of engine sound was the first indication the pilot got , even before he could confirm , albeit almost at the same time , the same from the engine instruments . Alas in Ajeet this important input was missing . According to me this was an undesirable trait , While at Sulur I had taken up this aspect with Maintenance Command and Air Hq. I am not aware if any action was taken .

Would like to know what seasoned Ajeet pilots felt about this particular aspect .

Another thing to leave lasting impression happened on the landing run . Ajeet had totally different brake system than the Gnat , except that both were toe operated there was nothing common . When the brakes are applied , toe pressure on both the brakes is more or less equal . In the Gnat , this more or less did not make much of a difference , the pilot by varying the toe pressures could manage to keep the aircraft straight and under control . . This more or less equal business did not work in Ajeet . If the toe pressure was more on one side , the wing on that side went down . So one tried to vary the toe pressure by reducing it on that side and increasing it on the other side , this would make the other wing go down !! I called it “wing rocking ” on the landing run . The amplitude would keep on increasing UNLESS the toes were totally removed from the brakes and the the brakes were reapplied . This obviously would result in increased landing run !!! Not a happy state if you were operating from 1700 yards runway and doing one odd sortie in a blue moon . May be with experience one avoided this “wing rocking” but with my limited experience and very widely spaced sorties I could not manage to eliminate it completely .

Ajeet was developed from the Gnat and though the outward appearance was same with lots and lots of commonality , with my experience I felt that Ajeet and Gnat aircraft were as different as chalk and cheese . They were two different aircraft altogether .

I do not think I would have fallen in love with Ajeet the way I did with Gnat even if I had managed to pile up as many hours on Ajeet as I had on The Gnat (750 +)

12 thoughts on “AJEET Development”

  1. >steinemenns remark that “the Ajeet >range performance was >disappointing”.

    I never flew the Ajeet – I handed over the squadron after reducing the entire inventory of Gnats to spares (a tremendous effort by the men under an excellent Engineering Officer)in anticipation of the Ajeet induction.

    I however happened to be in Air HQs much earlier(AD Air Defence) in charge of the Gnat desk and remember expressing serious reservations in my notings about the range of the Ajeet when it was under development much to the chagrin of HAL bigwigs. Its range in the CAS role was so limited that you practically had to deploy/launch it from so close to the army formations that it was of little use. There were no drop tanks in the picture at that stage even though they may have been planned and I do not think they made very notable difference in the Ajeet’s final avatar.

  2. Agreed that the Ajeet’s RoA in the CAS role was inadequate from the operational point of view. But you get a different picture when compared with the Gnat.

    Please correct my figures where they are wrong.

    The Gnat’s internal fuel was 1590 pounds. Out of this, about 400 pounds would be consumed for start, taxy, take off and climb to altitude. 800 pounds was the reserve for joining circuit for landing. So 400 pounds was left for cruise. Some distance is covered during the climb and descent.

    The Ajeet had 900 pounds additional internal fuel. This entire amount was available for cruise. So the range is easily tripled. The important thing was to fly without drop tanks and to fly as high as possible. For ground attack, a Medium – Low – High profile would have been optimum.

    As mentioned earlier, the additional range was easily 500 nautical miles at altitude, equivalent to reaching Bagdogra from Bareilly.

    What is “disappointing” about that ?

  3. I had run into a similar problem with wing rock on the landing roll in the Marut when I first started flying it in 1973. Wg Cdr Tilak told me that quick application of aileron into the rising wing and then centralising controls would stop the rocking. I tried it and it worked like a charm.The stick had to be moved quickly from side to side till the rocking stopped. Later on whenever I briefed a student TP for a solo on the Marut I told them about this little trick. On the Ajeet,however,the technique may have worsened the problem because of the narrow track. Did anyone try this on the Ajeet?

  4. Refer Shyam Sir’s Comment above .
    It jogged my memory and I remembered a uncharitable joke prevalent at that time.Not withstanding what Thomas sir has written and due apologies to all Ajeet Lovers ,The joke went like this ” TAKE-OFF 09 ,BOMB MIDDLE MARKER AND LAND ON 27 “

  5. Velu Sir,
    you are at your best once again.The Gnat and it’s derivative were never ment to be any thing other than interceptors.CAP OVER HEAD RW/OVER ANY NEARBY TACTICAL AREA was what it was meant for..Owing to its size and agility,the Gnat was also ideal for short range forays into nearby, confined air spaces such as narrow valleys.I remember tactical formation exercises in the Pahalgam Valley.The small size and agility of the Gnat were it’s best assets and if not used intelligently,could embarras even the best.Here is one such incident.

    On a spring thursday,in 78,it was a CAP vs Strike. 18 mounted the strike with Sk Marwah mission leader and yours truly as No2.2 Sqn launched the CAP.The ancient P12 valiantly scanned but before any vector was given,the mandatory ‘2 MINUTES’ call was given by the strike..I spotted the Cap and ordered SK to continue and come up on my left after the attack .The CAP,led by KN Datta, had spotted us and were in phase with the strike.It was then just a matter of aligning in a falling leaf pattern and mop up the ‘raiders’.During this,after completing my attack,I was plesantly surprised to see my strike leader exactly abreast and gently turning away.Quick on the uptake,I immediately called up ‘Contact,tail clear,joining up.Sk acknowledged the call and that was that.I now started wondering,’whats wrong with SK,why is he turning towards base and climbing’.
    But as a good No2,I joined up neatly in fighting and awaited the next move.
    What had happened was this.Strike leader had gone ahead with his attack,while I was concentrating on the CAP and also aligning to my tgt.after my simulated attack,as mentioned earlier,I had mistaken the CAP who had chewed up SK, for strike leader who was, blissfully reaching Anantnag.CAP leader was probably impressed with his No2.Then came the call’Shorts,whats’ your position’.I promptly retorted ‘Right fighting’.

    Well Gnatties’,I’ll spare you the rest.Needless to say,the combined debrief was uproarius and hillarious.

    Arvind’Shorts’ Kumar

  6. Right – Gnat vs Ajeet! The two types (Marks?) have about the same number of hours on me (around 600 hours each) so I guess I could comment for what it is worth. Here’s my bit towards the discussion.

    When you approached the Ajeet you missed the DME aerials (that Toothless Garry would keep ripping off in combat on the G-Bird). Like the 1100 series of the Gnat you were gifted a Radio Compass to show you the way back home instead of the DME which sometimes told you when you were within 40 to 50 miles of home but the kicker never told you in which direction. When you got in into the Jeet-Bird you missed that lean-back at 20 deg lightweight seat with its side pads that made the Gnat such a pleasant ride and gave you the ability to pick up your tail-chaser at 600yards six o’clock. Instead you had a big box with the chute right behind your head and you were hard put to see as far back. On the positive side you had the confidence that you did not have to wait for 500 ft agl before punching out and, of course, the Martin-Baker reputation was well-earned. The Indian instrumentation was neat and uncluttered and quite well-liked though it did not occur to me at the time that Murphy could influence maintenance in the manner indicated by PM Velankar’ story on the rpm guage. The ISIS gunsight was adequate though you missed the older sight and T-10 rocket combination. (The Lances used to call up for a “four aircraft pulling up for direct hits” at Dulongmukh in 1972 whenever the RSO was a Battle-Axe and by golly, the RSO would be constrained to give four directs as the score). The ISIS, though not designed for air-to-air, was pretty good (I did once get a one round fired and one hit on the banner!). The port gun often still fired only the round in the chamber and the starboard none at all!

    In the air, the range was, I think, not materially different in the case of the G- or the Jeet-bird. The additional fuel in the Ajeet’s wings made up for slightly less than the fuel in the drop tanks but the lower drag made up for that. My log books show a number of 50 minutes to one hour sorties on the Gnat as compared to 40 to 45 mins on the Ajeet but that, I think, was attributable to ever-upward mobile bingos over 1972 to 1991. Ferry ranges and strike ranges were no less on the Ajeet than on the Gnat given the same bingo figures. Peter Steinmann possibly compared ranges with other contemporary western tech aircraft or against expected increases in range with wet wings. The wet wings made it mandatory to carry full fuel and therefore were not liked for Dissimilar air combat ( the Fishbed guys would be heading back home when the wet wings were still feeding – On the Gnat we would have taken clean aircraft preferably the 1100 series which did not have even the Tail (8th and 9th?) tanks. As all HAL built aircraft with wet wings the Ajeet too had its problems with wing leaks and some tai numbers had copious amounts of bostick on them.

    Night flying was great on the Ajeet with its integral lighting and a view of the Kanchenjunga on a moonlit night from over the Tista valley at Chungthang was indeed memorable. The low sitting height gave a tremendous feeling of speed on landing at night. I do not particularly remember any difficulty with its roll on landing but you certainly could not evaluate your landings (on the Gnat you measured flats and were thrilled on seeing half a flat of usage). The Trainers had much less range of course but they were really good for their training ability. The rear seat had very good visibility with its internal periscope (even at night) and the training systems were terrific to work with.

    An interesting point was made in the discussion on the acquisition of the Gnat for evaluation by the USAF for radar trials. In 2 Sqn in the last days we did some DACT with Mirages too with a view to learn survival in an ASF environment. Even on the defensive Ajeets would paint on the Mirage radars at only 7-8 km when the Ajeets would also have visual contact and could initiate their defensive turns in time. After the first head-on cross, you know, two Ajeets could even contemplate an offensive attempt against a single M-two grand ! A stealth aircraft ahead of its time?!

    Actually both versions were great aircraft at any time or age!

  7. I couldn’t agree with Rajaram more.Never had a problem with the Ajeet both by day and night. And found it to be quite stable while dropping Spanish retarder bombs too!

  8. I forgot to mention earlier that the Ajeet had a very good six-degree freedom of movement, HAL built simulator on which one could fly not just IF but even practice air-to-ground armamaent delivery! Of course, one could shoot and analyse approaches.However, the simulator was unserviceable most of the time during the Sqn tenure and finally became fully serviceable only when the Ajeets were to be grounded permanently.
    The brand new complex housing the simulator was handed over to the Lightnings, brought in by a course-mate, Randy, who handed the outfit over to Limey, another course-mate and good friend. But what did the AF do with the simulator later?
    And, Chibbs, sir! What kind of results did you get on the retarded bombs? We found the max mil drop on the ISIS quite inadequate and the “1001…1002…” technique made us quite unpopular with the metal-pickers at Dudhkundi!

  9. Dear Rajaram ,

    Great write up . May be after some more hourson type , I also would have sorted out the rocking and may be liked it a littlt bit :-).

  10. As a school boy at Ambala,1961-64,i used to get thrilled watching Gnat(s) carrying out aerobatics in the local skies.In the name of early morning walks i often found myself standing on top of a 4″*4″ concrete pillar (fence)bordering IAF stn runway, looking at taxing and take-off of Gnats, AN-12s…
    I was delighted when in 1972( after M.tech from IIT Kanpur,1971)i was put on Ajeet project at HAL Bangalore.I worked on the fuel system of Ajeet Aircraft.
    The word in HAL about Gnat was that even if you removed all the inspection panels the aircraft still maintained its contours. Such was the packaging on Gnat. On Ajeet it became all the more compact.
    As an aeronautical engineer i consider myself fortunate to have my first project on Gnat/Ajeet.It was a great learning.How to package equipment in the smallest space with good acceability. This helped me greatly in all my projects in future.

    In 1974 when i returned after my marriage, i was told about a problem in the fuel transfer from Drop Tanks.
    We still worked with fuel tank option those days.Consistantly one side Drop tank would empty and soon thereafter fuel from the other fuel tank would stop transferring.I carried out the checks and cofirmed the problem.While sitting on the aircaft dorsal i figured out that fuel transfer would stop if the pressure in the second tank built up.This could happen if the higher pressure from the empty tank reached the second tank.This meant that thre was a leak between the LH and RH wing tanks.The Drop tanks and Wing tanks were in series respectively.Upon further investigation i found that a colleague of mine, had got a hole drilled in the wall separating LH and RH wing tank so that the two wing tanks experience equal pressure, resulting in lower stresses.He got it done when i was on my marriage leave.
    The intention was good but it resulted in fuel system malfuction.After plugging the hole the fuel system worked perfectly.
    One feature on the fuel system was a three way ball valve which could isolate the wing tanks in case of a bullet hit /leak in the wing tank.The fuel from the fuselage tanks could still be available.I hope no body had the occassion to use this feature.

    So proud, attached and emotional i was on this project that when Wg Cdr Tilak took-off on the first filght of E-1083,tears rolled down my eyes.After the flight when Wg Cdr Tilak confimed that the fuel gauge(showing only the fuselage fuel,during initial flights)was “rock steady” while the wings transferred the fuel, my happiness knew no bounds.

    Once in 1996 when i was driving past E-1083, the first Ajeet prototype, displayed in front of HAL corporate Office in Bangalore i told my son(6years) that i worked on this airplane, he just commented “as if”.

    While working on Kiran Mk-II project with Orpheus Engine,during layout stage,i found that the air channel meant for Viper enginer had to be abruptly increased in diameter to match the Orpheus engine intake diameter.This meant a very wide angle diffuser, diffuser angle going upto 20deg.This would result in flow separation and was clearly not acceptable.I brought this to the notice of my boss who in turn informed the program manger.This program manager was a very big shot and often very adament.He overuled and ordered that no changes will be made in the front fuselage.
    This direction meant that the air intake and the airchannel in the front fuselage designed for Viper engine shall remain unchanged and will abruptly change in the rear fuselage to match Orpheus engine diameter.This could result in flow separation in front of the engine. Ignoring this drawback,the first prototype was built with this airchannel.Wg Cdr Tilak had a narrow escape during the first flight.He noticed unusual increase in JPT during the flight and landed.On inspection after the flight the inlet guide vanes of the Orpheus engine had failed.This happened because of the separated flow entering the engine.Mass flow disturbances caused JPT to rise.After this incident i was given full freedome to design the intake and airchannel for Kiran MKII.The new intake and airchannel worked very well on Kiran MKII.It was designed to provide adequate air mass flow to the engine during sudden opening of the throttle at approach, a must feature for a trainer aircraft.

    Of all the Marut variants studied(HF- Adour,HF-RB199,HF-M53,HF-R88)during my association, HF-M53(Single Engine)was the most promising.Alas it never saw the day light.Some one should write a dedicated story why each project failed to get promising engine for HF.

    Later years i had the maximum satisfaction of my life when PTAE-7 became the first indegenously designed jet engine to power an aircraft, get certified and enter production. Ofcouse it took unacceptably long time.Reletively, GTSU 110, used on LCA for engine starting, took much less time for the design and development.I had the great opportunity working on these projects from inception.

    Within India HAL is a great place to work for any aeronautical engineer.We were always expanding the national tachnological capability envelop given all the limitations.
    R&Ds in the private sector really needs to catch up. My later years in the Automobile sector brought me more money but not technical satisfaction.
    Hats off to Gp Capt Kapil Bhargava for writing his own story and documenting many developments in indian military aviation in a very interesting manner.
    His work will go a long way.

  11. The title should read should read ’11 comments posted on “Ajeet development”.’

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