Bangalore: The geopolitical factor that determined state-owned Air India's choice of commercial aircraft in the mid-2000 may come into play again in the Indian government's selection of engines for its indigenous light combat aircraft (LCA) Tejas.

In 2005, when the national carrier's order for 50 aircraft worth $6 billion went to US aerospace company Boeing, its French rival Airbus Industrie had said it was the "geopolitical factor" that had clinched the deal.

An IAF official, who did not want to be named, said IAF want the EJ200 to power Tejas so that there is no delay in building the LCA with enhanced power. The government is currently carrying out technical evaluation of the two military aircraft engines.

"The thrust of EJ200 (about 85+ kilonewton) may be slightly lower than F-414 (95+ kilonewton), but it will easily fit into the LCA. And if the weight is reduced, its (EJ200) power will be adequate. Thus, we will not have to change the design of the fuselage," the official said.

The official said since the F-414 was a "fatter" engine with a bigger diameter, it could require redesigning of fuselage. "And if that happens, then all the test flights, many of which have already been carried out, will have to be repeated and the whole programme could get considerably delayed. It will also escalate the cost."

He, however, said the price of the European engine was higher than the

The F-414, by contrast, STARTS at 80 kilo-newtons DRY and is programmed for a thrust upgrade. Its core, unlike the EJ200, can be bypass ratio modifed easily, a la the YF-120, into a supercruise engine.  That is where its modified F-404 core, wound up originally before the $q.

IAF wants EJ200 engines for Tejas, but..

The EJ-200 is a fine engine at 60 kilo-newtons dry, but...........

 

Its design will top out at 80-90 kilo-newtons thrust, even with reheat.

 

It isn't crap. Like the F-404 to F-414 progression, the only way you are going to get more thrust out of that maxed out engine is to redesign the core front to back to run hotter with more air sucked through. You will have to change the front end fan, change the bypass, use special high temperature titanium and ceramics in the compressor stages, and modify the combustion burner geometry in the pot as well. Smaller diameter means less total airflow intake and less topout exhaust thrust after that redesign takes place. You  have less total air mass you can shove through the constricted diameter pipe of that smaller engine.

 

.You see BIGGER is better as you can top the F-414 out at 110 kilo-newtons easy now just by raising the engine core temperature as it is about 150 degrees centrigrade, which you cannot do, as with the current EJ200. It already runs as hot as  the engineers who designed it, dare to run it. Certain modifications with the EJ200 means a NEW engine that can accept the 250 degree centrigrade higher temperatures. So let's not kid anybody here about these EJ200 claims and don't believe the marketing hype, okay?

 

Have a nice day.

 

   

The problem is that Indian airforce doesn't trust in HAL's ability to modify and test Tejas airframe in timely manner, so they don't want to take any kind of risk and seek a drop-in replacement for F404, not something that requires modification.

 

Going from F404 to F414 does require airframe modification to increase airflow volume, as was the case with Gripen NG and T-50 Mk. 2(Mk. 1 accepts F404, while reengineered Mk. 2 airframe for F/A-50 and USAF T-X bid accepts F414, but lost 15% of internal fuel capacity to increase airflow volume) 

The EJ200's requirement was for 90 kN reheat thrust with a 15% thrust growth by reprogramming the DECU to allow for higher operating temperatures. It is indicated that the production version used since block 2 aircraft is already stronger by default and there is a switch to the left side console which allows a 15% increase in dry thrust and 5.5% in reheat thrust. That's a so called war setting which can be deactivated for peace time operations if required. A 30% thrust increase would require hardware changes and Eurojet envisages a new core and fan with a slightly increased diameter to allow for a greater airflow, the intakes are designed to accomodate with these changes, without redesigning them. So it's obviously false that the EJ200 tops out at 80-90 kN at the moment.

A new engine front to back MK. You just don't "slightly" increase the diameter of a core inside a tube. You also cut engine hours almost a third when you cut in war overheat, (not unique to the EJ 200 since US engines of the F400 series have the same design feature), so when you burn it out, its unsafe to rebuild, as it is now. The EJ200 is a very good engine, but its designed already to run to its safe hot limits. There is no way to claim a better bypass ratio and a larger tunnel here without enlarging the shroud to take a fatter core.

 

 

       

A new engine front to back MK. You just don't "slightly" increase the diameter of a core inside a tube. You also cut engine hours almost a third when you cut in war overheat, (not unique to the EJ 200 since US engines of the F400 series have the same design feature), so when you burn it out, its unsafe to rebuild, as it is now. The EJ200 is a very good engine, but its designed already to run to its safe hot limits. There is no way to claim a better bypass ratio and a larger tunnel here without enlarging the shroud to take a fatter core.

Yeah - they may as well order the Typhoon or F22 *replacement* blind right now, stamp the thing "case closed" and save all the money involved in shovelling paper forth and back :0

 

Gut feeling, if the EJ200 is a straight fit, they'll go with that rather than rework the fuselage on the carrier A/C.

 

But that's a wild guess and too logical for the Indian procurement guys!

 

Ian

 

 

 

 

 

You know, I have a feeling that we're still going to be discussing Tejas and MRCA what-ifs in ten years from now, so slow Indian procurement / weapons design is... I'll be excited once they actually make a (definitive) decision !