Home' Aerogram : Aerogram 2009 3 September Contents Aerogram September 2009
varnished to enable the fabric to stick on the woodwork
when doped, also all turnbuckles and nuts locked in the
All joints in the fabric should be made of the double balloon
seam type with double stitching, which must be brought as
close as possible to the edge of the hem of the seam, so as
to prevent the fabric from bending away from the surface of
the wing, the sewing to take the four thicknesses of the
Fabric should be laid over the leading edge and sewn up to
the trailing edge, and should be fairly taut and not too taut
Doping and Covering
All fabric must be treated in the following manner, when
using Raflite, Cellon, Emaillite and Britannia dopes (the
above dopes are supplied ready for application)
Seaplanes: the upper surfaces of the wings of seaplanes
should receive 4 coats of dope after which 2 coats of
pigmented oil varnish (PVO).
In cases where PVO is not available, a good boat varnish
diluted with equal portions of petrol may be employed.
Land machines: The upper surfaces of the wing of land
machines should receive 5 coats of dope only. No
transparent varnish on the undersides of land machines,
TOV is reserved for the undersides of doped fabric on
seaplanes only. POV is used for the upper surfaces of wings,
tail planes, elevators and fins etc, and the object is to protect
the dope from the actinic rays of the sunlight, forming an
opaque screen through which the actinic rays of the sun
cannot pass, thereby preventing decomposition. In certain
cases viz: Handley Page machines, POV is used for under
surfaces as well.
Fixing Fabric to Ribs
The fabric is to be fixed to ribs in the following approved
manner either by:
(1) Sewing to the ribs with sailmakers twine (stubbing)
(2) Fixing down with cane strips. If method I is employed the
twine is to be waxed, must be further secured by a double
knot at each stick, so that in case of the twine breaking the
whole fabric does not become loose on the rib.
Doping and Varnishing
Should be carried out in as dry an atmosphere as possible
and successive coats are to be put on as soon as the
preceding coat is dry.
When doping and varnishing great care should be taken to
apply it to the plane quickly and evenly otherwise it leaves a
All doping should be carried out in a temperature of at least
65 deg. F.
The fabric must on no account be sandpapered, but a piece
of old doped fabric may be used to obtain a smooth surface.
It is important that all brushes and containers for dope must
The pitch of stitch must not exceed 4 inches. All knots to be
tied on the upper surfaces. The stubbing must be covered
with strips of frayed fabric about 11/2” wide.
If method 2 is used, brass screws must be used to secure
the cane strips.
Fabric on Fuselage
In machines where fuselages are covered with fabric, it is
the practice to have the joints in the fabric laced so as to
provide a ready means of inspecting the fuselage or truing
When lacing up fuselages this cord is to be securely
fastened by double knots at every 12th pair of eyes, so as to
prevent the cover from slipping off in the event of a cord
Warp and Weft
The warp of the fabric is the thread running lengthwise.
The weft is the thread running crosswise.
All British aircraft must be painted with an identification mark
Blue ring 5 ft in diameter 1 ft in width
White ring 3 ft in diameter 1 ft in width
Red disc in centre 1ft in diameter
The rudder and the aft part of the tail fin should be divided
into 3 vertical stripes red, white and blue. The blue nearest
Machines with covered in fuselages are to have similar rings
painted on the sides of the fuselage, a short distance abaft
the trailing edges of the main plane.
The number of the machine is to be painted on the aft part
of the fuselage in figures 4” high.
No varnish of any kind must be applied over the
identification circles on any type of machine.
Use of Dopes
Only the following non-poisons dopes are to be used in
A: For use on machines of first class military importance:
B: For school machines:
Cellon No.NP2 made with acetone substitute
Britannia (Clark’s dope)
Acetone substitute: 90% Ethyl-Methyl Keytone, 10%
In stripping a plane care should be taken to notice how the
fabric was put on previously, as the makers generally know
by experience the best way to cover the different kinds of
planes to be met with.
Remove all fittings such as strut sockets, etc, and label
them so that you can replace them easily. Then remove all
the old fabric, any ribs that are broken should be replaced,
and all wires and metal parts should be painted.
This is usually done in the repair shop before the planes are
sent into the covering shop.
All metal parts likely to come into contact with the fabric
should be covered with tape or strips of fabric.
Aerogram September 2009
A Rigger’s Notebook
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