The Fly in the Flow ointment                                                    Prof.Prodyut Das






Roy has posted on Twitter two pictures to refute my claims that the Tejas canard location is risky. He claims that the above pictures- the upper at twenty five degrees AoA and the lower one at fifteen are “facts” . The pictures- it seemed dodgy to begin with and I was not alone. Mr. Village Hindu have pointed out that the intake flow is not shown and Mr. Prasenjt Das pointed out the lack of Incidence on the canards I thought my following would be of interest to those following the Tejas saga.

1)      It seems that the fore plane or canard, is kept at zero or near zero incidence. There appears to be  no change in the fore plane angle with a ten degree change in AoA. It is poor design then . Can anyone confirm the fore plane angles? You will also note that the greater vortices shed by the canard in teh upper picture seems entirely due to the change in AoA incidence and is creating  “drag” .Note that unlike the wing LE slats assisting the flow in the lower picture the flow on the canards is separating in the upper picture. This would also mean that the entire cranking effort of the fuselage would be coming from the elevons at the TE of the wing which is wasteful of the canards. I very sincerely hope this picture is not ex-ADA but some amateur's effort.

2)      The Canard AoA is zero which surely defeats the purpose or cripples its contribution. If on the other hand the canard was kept at a reasonable angle – see the LE flaps in the lower picture-the flow on the canard would be smoother –more lift and less drag. Perhaps ADA should consider a flapped /LE flap canard? This makes me suspect the picture. If authentic it indicates both carelessness and possibility of drag reduction

Finally I repeat : two “benign” cases shown does NOT represent FACTS but a Red herring Mr .Roy  We need to look at the malignant cases. There would be cases where the Canard would have an angle of incidence  and the flow and downwash would enter and disturb the inlet flow  How the F404/414c would then behave is pure conjecture as we don’t own the engine. As I have repeatedly said If I were ADA/IAF/MoD I would worry.

From what is reported it seems that ADA is NOW working on rectifying this area. This is depressing. People who are supposed to sleep and breathe aeroplanes should be quicker off the mark.

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