JayS wrote:You cant possibly tilt thrust vector 90deg for rolling TO elese there will be no forward thrust at all. It only works for VTO.
You can see what I'm talking about below. Its not 90 deg but probably closer to 45 on take off. Yet right after take off swivels to what looks closer to 90 deg. Now why it is even using 45 deg swivel on a ramp in the first place? It must be offering some kind of advantage in lift vs a trade-off in forward momentum. A physicsts should examine if there is anything to be gained by using slight thrust vectoring in aiding short take off from a carrier. That might well be the answer instead of hoping for a more powerful engine - which may never come! Foreign nations are in the business of screwing us over time & again.https://www.youtube.com/watch?v=H2G36gH1ylI
NLCA doesnt need Thrust vectoring which would also increase empty weight and reduce performance in the air further. It just needs a powerful engine or reduced flab. If only we could get F414 EE with 115kN thrust.
I'm not talking about adding a heavy swivelling nozzle on the engine. I'm talking about plate deflectors (i don't know what else to call them).
Look at the back of the Shinshin's engine. Something like that isn't going to add significant weight and if it improves maneuverability in the air for a slight weight penalty - all the better.
Trying to think out of the box here.
Please understand this - All you are trying to do is divert some power from already underpowered engine from longitudinal axis to vertical axis. You don't need Physicists to assess the situation. Engineers have already built and tested these systems for decades now. Its more efficient to produce lift by using thrust to increase speed. Thrust vectoring is rather inefficient way of getting lift. None of the VTOL aircrafts have TV merely to assist it in STO. On contrary, STO is used to increase TOW when VTO is not a necessity. Basically Ramp is to help reduce need/extent of TV, and not the other way round.
And you cant just TV at the fag end of the jet. It will pitch up the jet violently. Already there is excessive pitch rate in ramp TO at the exist. The FCS needs to keep the AoA in control. You can see how they had this issue in NLCA as well in the first flight. The pilot controlled the pitch up using stick input. See the Aero India Seminar on NLCA. Should be easy to find. So some part of the lift that you get from TV is lost in balancing the pitch up by creating negative left elsewhere and/or increasing drag significantly, unless you have additional vents, fan to balance it with thrust lift, creating which is too much work and impractical for NLCA.
Plate deflectors are very inefficient. You will see high loss in thrust. Normal circular TV itself can reduce thrust by 10% and F-22 style TV could reduce effective thrust by even 20%.
All those jets which have TV have significant excess thrust available. Putting TV on already underpowered jet is a bad idea.
BTW those deflector plats used in the Japanese jet are for the prototypes and as I expected they are temporary. They are developing proper TV a la Su-30 for the jet. The deflectors seems to be inspired from X-31. Its a easy and quick method to get TV, good for prototypes and experimental jets only.
In short, with TV, the effective thrust will decrease, using a part of it for lift is inefficient, and reduced thrust component in forward direction will only extend the time the jet needs to accelerate to the speed at which it can generate enough lift to hold itself in air.