The Aerodynamic Characteristics of Airfoils at Negative Angles of Attack Page: 3 of 37
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2 " 1(yA,. Technica Not e o. -412 . : .
The need for addi.tienal.l dc-ta-l-n -this range was re-
cently experienced by the Bureau of Aeronautics, Navy De-
partment, while they were"forulating rational procedures
to be fol1:l-owed-i.n -designing airplanes .:f or .th.he:dive and in-
verted flight conditions, Accordingly, a number of air-
foils suggested-,Jby.:the Bureau of Aeronau-ti-cs and a number
of N.A.C.A. airfoils were tested at negative angles of at-
tack in the N.A.C.A. Var.iab-le-den.sity pind tunnel at a
Reynolds Number of approximately 3,000,000.
Part of the results rer.e..published in a preliminary
note (reference 1) before the tests were completed. The
present report gives all the results, including those pub-
-tlshed in reference ..1 and the results -of previously .un-
puBl.iU-sh.ed, tests .of t-he :airfoil s -a-t posit viye .angles of at-
-t a- .
- A. PPARATUS AND METHOD -i
-,- A brief descriptiogn..of the redesigned variable-den-
s.ity -wind -tunnel ,and :its. ,ethod of operati-on will be found
in reference 2. The customary 5 by 30 inch polished du-
-ralumin airfoils were used in .the tests. In reference 2
will -be found a descriptio-n af. the method of constructing
the airfoils. The -specified ordinatea.will be found in
Table I.
The airfoils were tested in the .usual manner (as de-
scribed in reference 2) except for the method of.mounting.
on the support struts. When airfoils are t-ested at posi-.
tive angles of attack they are mounted on the support
struts of the balance .with the sting and .struts attached
on the flat side. For these tests,. however, the airfoils
were inverted and the sting was placed on the curved sur-
face to leave the flat surface free from obstructions that
might affect the value of the maximum negative lift coef-
ficient.
The measurements of lift, drag, and pitching moment
were :ade at a pressure cf approxi:mately 20 atmospheres
and an air speed of arrrcxmlately 70 .feet per second,
which correspond to a REy rnolds u,..ber of .3,100,000. The
tests at positive angles of attack were made under.'the
same conditions.vW- MMF, PV " *'-. " ". . --. W- W--i m AjClr .. - tW W v- - - -
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la~m ~rf~ Y,~~
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Anderson, Raymond F. The Aerodynamic Characteristics of Airfoils at Negative Angles of Attack, report, February 26, 1932; (https://digital.library.unt.edu/ark:/67531/metadc54075/m1/3/: accessed May 3, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.