Thursday, July 22, 2010

LCA HAL Tejas vs JF 17 thunder / FC1

Guys here is my another post. many peoples have been comparing these two air crafts. So here i present my comparison.


The engine used in JF-17 is RD93, a modification of RD33, the same engine used in older Mig29. The engine though powerful enough is known to be lazy and not good at acceleration. Also the engine is very old and newer Migs use a newer variant RD33MK of the engine.

The thrust provided by the engine is around 49.4KN without the use of afterburners. With the afterburners, the thrust is 84.4KN. Also its worth mentioning here that this old Russian engine like its counterparts is known to have problems sustaining its afterburner for longer duration of time, which suggests that most of the time the aircraft would be flying without its afterburners on. So the important thrust specification here is the 49.4KN, which by today's standards and the weight of the aircraft is quite low.

The thrust to weight ration comes out to be 0.78 for an empty aircraft and 0.55 for a loaded aircraft which is a SERIOUS drawback. Its the biggest problem with the current batch of JF-17 aircraft. Even with the afterburners on the aircraft fails to exceed a ratio of 0.94 for a loaded aircraft, which is poor to say the least.


The airframe of the aircraft seems to be good enough. The stabilizers are good enough and shaped perfectly. The nose is also carved nicely to direct air to enter the engines. The intakes are also nicely shaped to hide engine blades from radar waves. The airframe is good enough and nothing seems wrong with it.

The only problem with the airframe is the material. The airframe is made completely from metal and a little use of some alloys. There has been no use of composites at all. This increases the weight as well as the rcs of the plane.


This is another field JF-17 is lacking in. The chinese avionics are just not enough. Although PAF is negotiating with France and now even Italy for an avionics upgrade, nothing is surfacing as of yet. The radar in use now is KLJ-7 which is a scaled down version of the KLJ-10 radar used in the J-10 of Chinese Air Force.

The range of the radar is 75 kms in look-up mode and 35 km for look-down mode for a target of rcs 3 square meters. Also the radar can monitor upto 10 targets in TWS(Track While Scan) mode and engage two in BVR mode.

The radar is obsolete by today's standards and it would need serious backing by AWACS in order to put up a fight. Also the missile that the plane will use for its BVR engagements would be SD-10 which is a chinese missile with a range of 90-100 kms. But as the radar is limited to 75 km for 3 square meter rcs target, the extra range of the missile won't come in handy.

The newer aircraft coming up have rcs of 1 square meter or below. The KLJ-7 would not be able to detect these targets at ranges beyond 30-40 km. In combat with these aircraft, the JF-17 would be shot down even before it can detect what hit it.

It is only after an avionics upgrade that we can analyze the true capabilities of the aircraft.


The only BVR missile compatible with JF-17 for now is the SD-10 missile. As of now, not much information is available about the missile. Even the range is speculative at best. Wouldn't want to comment on it.

LCA - Tejas


The engine in use for the first batch of aircraft will be GE F404IN, which is a modified F404 engine, being used on F18. The engine has a max thrust of 85KN with afterburners on and 50-55 KN without afterburners. The engine is not powerful enough to allow Tejas to carry out combat maneuvers with its full load. This is the reason a new engine is being evaluated for Tejas. The new engine will have a thrust of 100KN with afterburner and 60KN without afterburner.

That would make it powerful enough and would increase the thrust to weight ratio from 0.95 with afterburner at full load to 1.07 with afterburner at full load and 0.64 at full load without afterburners.

Add to that an unstable delta wing configuration and that makes Tejas a really good maneuverable machine. The fly by wire does a great job at making it agile at high speeds. Speaking of speeds, the new engine might also enable supercruise for LCA. Also TVC can be seen if EJ200 is selected.


The LCA has a delta wing configuration without horizontal stabilizers which makes its configuration unstable. This means that it would require powerful computers and fly by wire controls to make it stable in its flight. Without these computers, it would be impossible to control the plane.
The airframe is inspired from Mirage 2000 and is a proven one. The huge wing span will add to the maneuverability. The Y-shaped intakes guarantee reduced rcs and there is nothing spectacularly contributing to the rcs of the plane.

The LCA uses a lot of composites to reduce the weight and radar detection of the plane. The size of the plane is another factor that contributes to its low rcs. This leads me to believe the rcs of LCA would be a lot less than that of JF-17.


The radar in use for the first batch will be a PESA multi mode radar ELTA EL/2032 radar. The air to air mode of 2032 radar has a range of upto 150 km for 5 square meter rcs and in air to sea mode has a range of 300 kms.
The missiles that this radar support are currently R77 and R73. The R77 has a range of upto 90 kms and it believed to be extremely maneuverable.

Also Astra Missile can be supported with the ELTA radar. DRDO believes its indigenous radar would be ready in a couple of years and its supposed to be better than 2032 radar.

So all in all, its Tejas which is more advanced and capable, but its not ready yet. In future, if JF-17 wants to match up to Tejas, an avionics upgrade is desperately required.

Tejas is much more then Thunder

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