chetak wrote:Pratyush wrote:Why do we need antifreeze for Indian operations requiemnts. I would imagine that heat generated by gas turbine would be sufficient to turn ice into water for injection into the engine.
Besides do we know for certain that Kaveri will be using water injection for extra thrust?
Its just an idea that is being tossed around.
The proposed plan is to store the water in the tail/vertical fin section of the aircraft.
rapidly consumable weights stored at the extreme ends of the air frame may produce CG problems of its own, depending on the weight, of course and especially during combat maneuvering.
Vina is proposing to use water injection only for TO and climb out. So the water tank wherever it is will be empty soon enough. (Surely during TO, there will need to be a small tweak to be needed in FCS though, but I think this should be fairly easy). Even in case someone wants to make fin a wet fin for fuel, that fuel should be consumed during idling/Taxing/TO itself. It will indeed need FCS modification otherwise. 100kg at ~5m from CG is similar to 500kG at CG. The fin itself will need modifications as its not fit for being a fuel/water tank as of now. Perhaps use of inner rubber fuel tanks can be made so that the composite structure itself would not need to be modified too much. Water is not good for composites. (In fact the very first composite usage in operational use is in Fins. Then, it was observed that they undergo fatigue failure due to water seepage as seeped water repeatedly freezes-liquefies when the aircraft changes altitude/Op conditions, widening cracks. The damage is typically undetectable from outside unless you do detailed NDT and this results in catastrophic failures one fine day.)
Main challenge would be to create the water injection system in the engine and related ducting in the aircraft. Had it been a fairly simple system, it would not have been dispensed with. There are a lot of complications associated with it. I don't think IAF will accept it.
However the proposal works well in theory otherwise.