Most civilian aircraft (the Cessna 150 included) have
many straight lines in their side and top views. Generally
speaking, from the trailing edge of the wing to the tail
post, most formers are straight. ;is makes plotting
formers and stringer locations much easier. For measuring accuracy, I enlarge the reference formers more
than the outline views. In this case, the multiplier was
2.72. Draw the forward former and then the aft one inside
it, locating both on the vertical centerline. Locate and
draw the desired former locations between these two on
the side and top views, placing one at the leading edge
of the stabilizer. Measure from the centerline to the top,
bottom, and sides, and mark on the former sheet you
are creating. With a 30/60-degree triangle, draw a line
every 30 degrees out from the centerline on both your
three-view and your new drawing. Add a line between
each 30-degree section to make sections 15 degrees
wide. Now measure from the three-view centerline to the
edge of the section, multiply by 2.72, and mark that line
on your plan drawing. Repeat this with each line. Using an
appropriately sized curve, join the marks to make your
model’s full-size former. ;e more complicated the shape,
the more lines and measurements are needed.
Wings and most tail surfaces are relatively easy to
enlarge. ;e only ones I would consider having enlarged
from a three-view would be an elliptical shape, such those
on as a P- 47 or Spitfire and some tail surfaces. Even
these can be enlarged, like the formers, by starting with
a reference line drawn down the main spar or hinge line.
Draw the rib locations and other lines if required. Measure
your three-view fore and aft of the reference line, and
connect the dots with your drawing curve.
For an 80-inch wing, I space the ribs 3 to 3 1/2 inches
apart. My choice for airfoils has always been the NACA
2410 to 2412. ;e “ 10” and “ 12” indicate the percentage of
chord thickness of the wing. Washout at the wingtips is
very important. I set the wing incidence at positive 1.5 to
2 degrees at the fuselage and 0 degrees at the tip rib.
Over the years, this has worked well for me. For the
Cessna’s wing, a straight 1/4-inch strip (under the
trailing edge) running from the first outer-panel rib to
the wingtip shims the ribs to set the 0 degrees for root
rib and 2 degrees negative at the wingtip (trailing edge
up). Depending on how scale you want your model to be,
the tail surfaces can be simple flat plates or drawn with a
symmetrical airfoil; either way works well.
For good flight performance, I like to set the stabilizer
incidence at 1 degree positive, (leading edge up). All of
the wing and tail incidence as well as the engine thrust
angles are referenced to the centerline of the fuselage. For
each rib, a reference line should be drawn from the most
forward point of the leading edge to the rear tip of the
As a rule, our plans’ top, side, and front views (formers)
are just enlarged outlines taken from our three-view
drawing. We have to draw the new outlines full size before
we can add all the internal details that make up the plans.
We do this working from the outside and working inward.
First, draw in the thickness of the wing and fuselage
sheeting, usually 3/32 to 1/8 inch. ;en, for the wing and
tail surfaces, we add the cross-sections for the main and
secondary spars and other structures. For the fuselage,
we add the stringers and longerons that will support the
outer sheeting. We then add the leading and trailing edges
and build up the structures around the hinge lines and
other hardware attachment points, such as the landing
gear, engine mounts/firewalls, and wing saddles.
Experience is required here to determine the wood
sizes. ;e best way to gain this experience is to actually
build a model or two from kits. You can also ask friends
who are model builders and look at plans for other
similarly sized models to determine the recommended
dimensions. For my 80- to 110-inch-span models, I use
1/8-inch-thick poplar plywood for formers, internal
plates, and wing saddles. Most stringers are 1/8 x
1/4-inch and sometimes 3/8-inch hard balsa. Hardwood
can be used along the edges of open areas, such as
hatches and gear doors. Fuselage and nacelles multi-
engine models are usually sheeted with 1/8-inch balsa.
;is provides enough thickness to allow adequate
sanding where glue joints and seams are not perfect.
As with anything new, start slowly and work your way
up. Pick a relatively simple airplane with lots of straight
lines and simple curves. A Pietenpol and Taylorcraft come
to mind as excellent first tries. Take your time, and have
fun. ;is is the other part of our hobby, which is just as
important as the flying part. ;
Above: Here, the wing inboard and outboard
panels are taking shape.
Left: Nick shows o ; the completed Cessna.
He chose the USAF Academy’s Cessna T- 51
trainer scheme—so, yes, this is a warbird.
Below: Using Nick’s standard wing and tail
incidence settings, the T- 51 flew great right
from the start. A Zenoah G- 23 is an ideal
engine for this 80-inch Cessna.