Page 136 - PROF-DHAWAN-COMPILED

GENERAL I ARTICLE

Over the next few days MolJymawk grew tamer and m'ore confiding towards Dorian, Do you think he
loves me, Tom? I shall want to keep him forever as my pet,' But on the eighth morning when they climbed
to the masthead the bird had disappeared , Though Dorian whistled for him' all that day, he wasgonc. and
at sunset the child wept bitterly, ..

Figure A. Theory of dynam-
Q wind protHt
ics soaring (Lighthill 1975). ',,41'"
(a) Phases in the soaring flight '-'-':.-:0--,: " ,,' win~wQrc:t A
1 dimb
h '.'ghaltihtAo/ 2 _-" ___ "... ~
. .",. .....-----..........
"-"',;'
.
of an albatross. (b) Dynamic It' .'Mlrd I ':...--.-l .... JQst tftWdrd ---......
'
,
turn " ,,';'" -__ ~id~
soarind: (1) rise into wind, (2) __ ..l._"",," , '3 '" ...... ----,
turn at highest point, (3) glide /' ':...,. -------1'-......... -"4 lowattitud.
" w~w~~m
down wind - build up of
speed, (4) turn and repeat (1).
(From S Dhawan, Bird Flight,
b r----------------~-----------------~
lASe)

Frame ()r ref., moving with ,bird velocity Va (U , V 8' WI)
a
Energy equation in moving frame of reference:
Total energy of bird == rate ofworkin'gof inertia force
- rate 6110s5 by drag
(1 /2lmV! + mgz= - [my. (dV/dZ) ]0. - OVa
K. E. P. E. . I nertia force Loss due to drag
Ppsitive if (u. v..,) is negative

modern education has ignored connecting nature and technol-
ogy, and exhorts teachers and students to hone their experimen-
tal skills (Box 2).

Comparing birds with aircraft is a popular pastime for pilots and
the public alike, but it is important to emphasize that bird flight
is seldom steady. Most birds are either flying up or down or

________ LAA~AA, ______ __

34 v V V V V v RESONANCE I October 2003