"john smith" wrote in message
...
In article ,
"J.Kahn" wrote:

Does the presence of the
slot in the flap move the overall wing CP forward or aft vs the
unslotted flap at a given angle? This is what I'm having trouble
finding out. I would think that the presence of the slot imcreases the
pressure gradient and moves it more aft than the plain one, so that the
pitching moment is increased.

AS Stealth Pilot posted, the purpose of the slot is to energize the flow
over the flap.

A better question is, what are the relationships between center of
pressure (CP) and center of lift (CL)?

Do they differ?

Why do they differ?

Under what conditions do they coincide?

There are a lot, if not all, of the old NACA reports online these days on
the NASA Technical Reports Server at:
http://ntrs.larc.nasa.gov/search.jsp?N=279&Ne=25

I got to the following by simply entering the search term: slotted flap
http://ntrs.larc.nasa.gov/search.jsp...matchall&Ntt=s
lotted%2Bflap (If that URL wraps, you may have to cut-and-paste or run the
search again.)

If you don't find the info on NTRS, the next easiest method would probably
be to built a couple of mock-ups and project each of them well outside of a
car at a time when there is no wind; such as is frequently the case in early
morning. (As you may have guessed, I am too lazy and cheap to built a wind
tunnel--and I suspect intuitively that this is the sort of test in which
interference from the floor and ceiling of the tunnel would have a major
influence.)

Peter
(Not an aerodynamicist)