Drag Tests of an NACA 65(215)-114, a = 1.0 Practical-Construction Airfoil Section Equipped with a 0.295-Airfoil-Chord Slotted Flap Page: 4 of 36

                                
NACA TN No. 1236

bf

flap deflection

8    effective boundary-layer thickness, distance frm airfoil
surface to point inside bouaxdary layer whore inside
velocity is equal to 0.707 of velocity outside boundary
layer
Rg   Reynolds number based an effective boundary-layer thickness
U    local velocity outside boun dary layer
To   free-stream velocity
IIESCIPTION OF MOIL
The model was built to the ordinates of the NACA 65(o5)-i14
airfoil section. The ordinates for this e socticn  zy be obtained by
the method outlined in refref hce 1. The model had a chord of
85 inches and a span of 35.75 inches. Tho spars cntor lines were
located at 8.2, 37.3, and 68.8 percent chord.  Between the front
and rear spars tle akin was appro-ximatoly 0.7.5 inch thick and was
built up in th-e following manner:
Material                    Thickness
(in.)
ural inner plate                 0.072
Dural inner skin                   .025
Balsa core                         .600
Dural outer plate                  .040
Dural outer skin                   .016
o0.753
The inner plate was cycle-welded to the spars and ribs. The remaining
components were sandwiched. together and bonded by cycle-weld and, in
turn, this sandwich was cycle welded to the inner plate. Ahead of
the front spar the skin thicknoss tapered don to fair into the nose
skin,which was approximately 0.28 inch thick, and was built up of a
0.250 balsa core sandwiched between two dural sheets 0.016 inch
thick. Ribs extended fran the front to the rear spar at each end of