Stage 1: Building The Wings; Preparing The Wing Ribs; Setting Up The Wing Spars - Model Airways CURTISS JN-4D JENNY Instruction Manual

Plan Sheet 2 shows all the details for con-
structing the wings, wing struts, and rigging
drag wires within the wings. In addition,
refer to Sheet 6 and Stage 7 for rigging the
kingposts on top of the upper wing that can
be done during this stage if desired. The
following parts are required for this stage:
Laser-Cut Wood Parts
Upper wing ribs – 2 of W1
Upper and lower wing ribs – 4 of W2
Upper and lower wing ribs – 22 of W3
Upper and lower wing ribs – 12 of W4
Upper wing ribs – 10 of W5
Upper wing ribs – 6 of W6
Upper and lower wing ribs – 4 of W7
Lower wing ribs – 2 of W8
Lower wing ribs – 2 of W9
Upper wing ribs – 2 of W10
Lower wing ribs – 2 of W11
Upper wing ribs – 2 of W12
Aileron ribs – 4 of W13
Aileron ribs – 16 of W14
Center section ribs – 1 of W15
Center section ribs – 2 of W16
Center section wing struts – 4 of W17
Interplane wing struts – 8 of W18
Kingposts on upper wing – 4 of W19
Lower wing handhold blocks – 2 of W23
Wing building jig shims – 20 of W24
Britannia Castings
Aileron control horns – 4 of C1
Aileron control cable sheaves – 4 of C3
Aileron control cable sheave bodies –
4 of C4
Wing strut end fittings – 20 of W20
Wing skid end fittings – 4 of W21
Photo-Etched Copper Parts
Single eye rig fittings for drag wires
and kingpost wires – 128 of R1
Double eye rig fittings for aileron
control horn brace wires – 6 of R2
Drag wire and kingpost wire turnbuckles –
54 of R3A(short)
Wing wire rigging plates at struts –
20 of W22
Wood Strips
(cut to length as required)
Rib vertical web stiffeners and cap strips –
0.020" x 1/16"
Wing strut and kingpost support pads –
0.020" x 1/8"
Stringers and miscellaneous wing stiffen-
ers – 1/32" x 1/32" and 3/64" x 3/64"
Front beam flanges, and shims for wing
building jig setup – 1/32" x 3/32"
Rear beam flanges – 1/32" x 1/8"
Front beam webs, and web blocks at
compression ribs – 1/32" x 5/32"
Support stringers for lower wing walk and
wing tip stiffener – 3/64" x 3/64"
Rear beam webs, and web blocks at
compression ribs – 3/64" x 1/8"
Wing tips – 1/16" x 3/32"
Aileron leading edges – 1/16" x 5/32"
Upper wing rear web in way of ailerons –
5/64" x 1/8"
Wing skids – 3/32" x 3/32" flexible
beech wood

STAGE 1: BUILDING THE WINGS

Front beam web between first two ribs
inboard and center section – 3/32" x
5/32"
Leading edge – 3/32" x 3/16"
Rear beam webs between first two ribs
inboard and center section – 1/8" x 1/8"
Blocks (to be carved) at leading edge
wing tips and handholds – 3/16" x 5/16"
Wood Sheet
(cut to length as required)
Leading edge cover sheet and lower
wing walk – 1/64" plywood
Steel Rod
(cut to length as required)
Wing trailing edge and struts between
kingposts – 1/32"-diameter
Fake wing hinges at center wing section
and fuselage – 1/16"-diameter
Brass Rod
(cut to length as required)
Pins for kingposts – 1/32"-diameter
Brass Strip
(cut to length as required)
Aileron fake hinges – 1/64" x 1/16"
Self-Adhesive Copper Tape
(cut to shape as required)
Bands securing trailing edge to ribs
and stiffeners
Rigging Cord
(cut to length as required)
Drag wires in wings and kingpost wires –
0.010"-diameter gray nylon cord
Wrapping cord for splices – 0.008"
diameter black nylon cord

1. Preparing the Wing Ribs

All wing ribs are laser-cut. For your informa-
tion, the airfoil is an Eiffel 36. There are sev-
eral different types of ribs, such as solid
compression ribs, where the drag wire fit-
tings are located, basic ribs with lightening
holes, shorter ribs in the upper wing center
section in way of the upper wing ailerons,
and the aileron ribs. The outboard rib near
the wing tip is a solid rib, more narrow than
the others since the wing tapers at the tip.
The inner most rib on each wing panel is
thicker than the others.
As the first order of business,
Rib stiffeners:
glue the vertical rib stiffeners on each side
of ribs where lightening holes are located, as
7
shown on the plan. These stiffeners prevent
rib cracking on the real aircraft. The thick-
ness of the rib plus the vertical rib stiffeners
on each side should equal the width of the
cap strips that are 1/16" wide. However, the
vertical stiffener wood supplied is 0.020"
thick (1/64" not available). Before gluing the
vertical stiffeners, block sand the strips down
to 1/64" thick if necessary. Test fit a cap strip
to make sure it is flush with the stiffeners.
Hard to do after the wing is assembled. Cut
the stiffeners flush with the top and bottom
of the ribs, except cut the one at the center
flush with the underside of the stringer
notches

2. Setting Up the Wing Spars

(Figure 1-1)
In addition to the ribs, the wings basic con-
struction consists of a heavy main front and
rear beam, two small stringers (upper and
lower) in between the main beams, a trailing
edge, and a leading edge. On the real aircraft
the main beams are a solid "eye" beam contin-
uous through the ribs. However, for the
model these beams are composed of an upper
and lower continuous wooden flange with a
separate web fitted in between each wing rib.
The leading edge is a solid continuous wood-
en spar, with the addition of a strengthening
cover sheet back to the center of the front
beam on the top side of each wing panel.
Small stringers fit into the notches at the top
and bottom of the ribs. These stringers are to
prevent rib twist on the real aircraft.
The trailing edge is a steel rod on the model
(tubing on the real aircraft). The rod splices
into a wooden wing tip on the lower wings.
For the upper wings, the rod is continuous
around the ailerons and is wood on the main
part of the wing.
Both the upper wing and lower wing panels
are similar in construction, so the instruc-
tions to follow are applicable to both except
for specific details which will be noted.
Setting up the spars:
without the upper wing ailerons. Build these
separately (
FIG. 1-1 RIB STIFFENERS
.
Lay out the basic wings
.
see Paragraph 11)
TYPICAL STIFFENER
.020" X 1/16"