Question on Flaps
Hi,
I am reading an aerodynamics book and feeling confused about two paragraphs which is about flaps.
"Think of the trailing-edge flaps at their early extension as lift flaps (when the lifting capability of the wing is increased significantly for an acceptable penalty in drag - say for take off)"
"When flaps are lowered, lift increases but so does drag. The drag increase is proportionately greater than the lift increase, even at small angles of flap extension, i.e. the L/D ratio is less with flap extended."
If the L/D ratio was less when any flap extension, why could a take-off flaps shorten take off distance (for some aircraft such as the C172)?
Thanks,
Issac