drag bucket

[rapidshot]

English is not my native language, so i am sorry in case of any misunderstanding,

my question is,
general form of drag coefficient is
drag=parasite drag + induced drag
lets forget about the second term for a while, as for the parasitic drag of the airfoil it is defined as "drag coefficient at zero lift" which almost makes the use of drag bucket impossible at various angle of attacks during flight, in one of the early Naca papers some attention was drawn here but not concluded
so, do the new codes or specs take this effect into account,

thanks

[PBL]

rapidshot,

my question is,
general form of drag coefficient is
drag=parasite drag + induced drag
lets forget about the second term for a while, as for the parasitic drag of the airfoil it is defined as "drag coefficient at zero lift" which almost makes the use of drag bucket impossible at various angle of attacks during flight, in one of the early Naca papers some attention was drawn here but not concluded
so, do the new codes or specs take this effect into account,


I am not sure quite what your question is, because it is not indicated with a question mark. Also, I am not sure what you mean by "makes the use of the drag bucket impossible". The "drag bucket" is a characteristic of perfectly machined laminar-flow airfoils, primarily the NACA 6-series. As far as I know, it turned out not to be particularly noticeable in the world of joined panels and rivet heads on real airplanes, so one couldn't really make use of the phenomenon in practical flight. However, those airfoils also had high critical Mach numbers (where the rate of increase of drag with increasing speed begins to be very high), so they were used on high-speed jet aircraft after WWII.

My knowledge in this area is relatively superficial, though, so maybe someone else has more to say.

PBL

[FE Hoppy]

The term "drag bucket" is used to describe the shape of a drag curve showing Cd against AoA where the drag curve shows an extended flat bottom of the curve i.e. bucket shaped.

This is plotting induced drag against alpha.