[pedantic hat on] (with a wave to Keygrip)
Each of those stages of flap add to the ability of the wing to create lift. They also add to the drag produced as a result. It's not really correct to say that 30 deg is all drag & no lift. Without appropriate data in the a/c's manuals it's difficult to say what the proportion of lift & drag increase is as flap is extended.
[/pendantic hat off]
Many a/c are approved to take off or land using a range of flap. Generally for take off as the flap setting increases, the a/c will get airborne in a shorter distance but then not climb as steeply. At some point the additional drag from increased flap is excessive. Fitting a higher horsepower engine could allow more flap for take off since the added HP can be used to maintain climb performance in spite of the increased drag.
C150 performance charts I've seen specify 0 deg for take-off & 0 to 40 deg for landing, with 40 deg specified in the landing chart.
On the other hand, the charts I've seen for C152s specify 10 deg for take off & 30 deg for landing. Cessna increased the HP as one of the changes between these two a/c. They also limited the max. flap setting to 30 deg.
Other a/c types use other flap settings eg C182 can use from 0 to 20 deg for take off, PA32 that I've flow used 0 for normal & 25 for short field deg, etc.
Last edited by Tinstaafl; 29th August 2005 at 00:48.