Re: ADA Tejas (LCA) - III
ersakthivel, I dont think its the powerplant or avionics which is falling short for maintaining a sustainable turn rate as warranted by the IAF, plus no other modern comparable jets have a pure delta form, either they are tailed or got canards, and in the performance scale I would rate a pure delta just as a beauty in simplicity not as an engineering marvel. While we should strive for the later.
cranked delta with a twist in the wing root does the same job of improving low speed handling according to ADA.
The canardrs were added to the design and tested and found to give no particular improvement in performance considering the extra weight and drag penalty it imposed ,there are snaps of tejas with canards wind tunnel test model on the net.The size of the elevons itself is enough for the specs according to ADA.
If they were wrong they would have proposed canards and tail planes in mk-2. Till this day, they haven't.
The fighter was made to replace the mig-21 with less than 2 tons external stores capacity when design was propopsed in 1983, when there was no single engined fighter with 5 ton empty weight capable of lifting 4 tons at the time.
Due to the fluid political situation predating 1993 and trenchant disbelief in IAF over ADA's ability ,no funding was given by the mod till 1993. Funds released on 1993 after the intervention of abdul kalam.That too only for two tech demos.
2001 first flight of tech demo 1.then for four years no other prototype joined the test flight team.
Compare that to 3 J-20s already flying within a year of first flight.
Then by the time all tech was validated by only two tech demo version for FOUR YEARS by 2005, The iaf changed the asr for 4 ton weapon stores comparable to other light fighters of the time.
The reason being the advent of near 200 kg long range BVRs that were not on IAF list in 1983, if only IAF has forseen this development ,giving a proper asr wit long term future in mind at the start, gtre would have embarked on a higher power bigger size engine from the first day itself, and ADA would have finished the job much earlier designing the proper weight fighter.
But the gtre kaveri engine program started much earlier for 1.5 ton pay load level thrust of 80 kns ,and they couldn't change the design midway, even though the k-9 achieved 75 kn nowadays in high altitude flight tests in russia.
ADA strengthened the wing and other parts of the structure to carry this extra load resulting in a ton weight increase to 6.5 tons.
Compare that to the sukhoi team's blank refusal to accomodate IAF's two seater version and stringent stealth requirement, which they accepted while receiving funds and now refusing, resulting in IAF reducing orders to 144 ffgas.
So with the lifting of sanctions LCA is awaiting higher thrust Ge engine to fulfill it's specs by IAF.
It is as simple and plain as this.
With the higher power engine all specs are achievable without canards and tail planes.
Note the su-35 terminator has dropped canards , but retaining the better performance.
So all sustained turn rates would have been achieved if further IAF increased ASR of 4 ton weight was not given.
Becasuse it would have reduced the plane's weight by a ton.
You yourself can calculate the increased twr and the resulting further increased lift per kg available to the aircraft with the present 80 kn engine, if the empty weight is 5 tons.
It would have achieved it's specs very easily if it weighs 5 tons and store capacity of 1.5 ton.
But some people are ignoring all this and running a motivated campaign in this thread against tejas beyond all reason.
All this information is available in the open.
Even the gtre chief alluded to this when he said in aeroseminar2011, that increase in all up weight of tejas due to the iaf's increased requirements has rendered the k-9 kaveri engine irrelevant.
So there is really no need for tail or canards to reach it's specs. The mk-2 with much better engine will prove all critics wrong.
No one needs fancy canars, lrex, tail planes for this purpose.
The naval version will have LEVCON to reduce landing speeds.
Low wing loading Deltas always have lower str than simple compound wing or high wing loaded fighters it is an aerdynamic fact.
If makers of F-22 adopted simple compound swept wings ofnolden days wing type they would have much better STR.
Also if the makers of PAKFA adopted simple compound swept wings of olden days wing type they would have much better STR.
Why didn't they do it?
Because it is the improved nose pointing ability of higher instataneous turning ability that is very important in firing high off boresight WVR missiles.
NO amount of higher STR will save you from the missile,
That is the reason low wing loading deltas are all prevalent in new fighter designs these days.
I don't want to add any further as already some members are making it a toxic experience for me to even log in to the forum.
thanks.
The ADA
