Hello,

I was reading on the net that the MiG-21 is a high demand no-nonsense
a/c, and tends to lose control (without the warning buffets as
experienced bu other a/c)
quite easily (during high speed turns??). Is this a MiG-21 phenom, or
do other Delta wing aircraft also have such inhernt control problems?


Googling brought out the following...
**********************
classic delta-wing aerodynamics problems:

1) vortex bursting
2) dynamic stall
3) falling-leaf mode" of asymmetric deep stall??


Dynamic stall is where you keep raising angle of attack really fast -
and
the lift keeps increasing - and then the wings stall. And stay stalled
when the angle of attack comes down - past zero, down into a dive....
************************

quote(From Wng. Cdr Suresh's article on Bharat-Rakshak Monitor):
-------------------------------------------------------------------------------
It is the docility of the aircraft that not only generates a good bit
of
confidence but also encourages forays into exceeding the limits of the
stipulated flight envelope. In air combat manoeuvres, many
inexperienced
pilots have got into trouble without realising it. At high angles of
attack, the induced drag increases sharply and unless the angle of
attack
is quickly reduced, the aircraft develops a high rate of descent,
which
cannot be arrested with the power available (even with reheat). Added
to
this, there is no protest from the aircraft like severe judder, wing
rocking. etc, prevalent in other types of aircraft. This gives a
feeling
of well-being and a number of pilots did not recognise the danger in
time
to take recovery action or eject
-------------------------------------------------------------------------------



A search has not yielded anything on dynamic stalling and other
problems of the MiG-21 other than in passing. Can anyone point me out
to a source on the net, or any specific paper/book which deals with
issues of Dynamic stalling of aircraft in general and delta winged a/c
in particular? Have any studies been done on other Deltas (Mirage
family, F-102/104) ?

And what in your view will explain the aerodynamic limitations of the
MiG-21?

Thanks,
Lars