Tiger Moth Rib Building Workshop
By Jill Oakes and Rick Riewe
The Brandon CATP Museum, Brandon RAA, Winnipeg Area RAA, and Canadian
Aviation Historical Society met at the RAA Workshop Final Assembly Building
March 8th for an evening workshop on building Tiger Moth Ribs. About 20
people came out on a blustery winter night. Unfortunately the RCMP closed
the Trans Canada Highway due to black ice and blowing snow, keeping most
of the Brandon participants from attending. Harvey McKinnon, Brandon CATP
Museum Pilot, explained that the Museum had three flying airplanes – Cornel,
Stinson and Harvard…and one day the Tiger Moth will be added to the flying
This Tiger Moth was built in 1938, last flew about 20 years ago, and
has been on static display inside the hangar ever since. It is now being
restored in a joint project with Brandon and Winnipeg area RAA Members.
Tom Phinney and his son have volunteered to be the AMO: Fabric and Wood
for the project, Ted Hector has volunteered to be the AME. Volunteers working
on the project include neighbours, experienced builders, and pilots. Gerald
Ricard, Transport Canada, is providing advice needed to ensure the paperwork
is all brought into order. His colleague, Garnet Fedorowich, Transport
Canada, is familiar with this Tiger Moth, he was working in Brandon when
it first arrived at the museum about 40 years ago and has followed its
repairs and uses with interest. Garnet has been invaluable helping recover
some of this history. Bill Gibson drops in regularly with precious insights.
Bill actually flew this Tiger Moth many years ago and has brought in invaluable
documentations on rigging specifications! Neil Davidson, a re-known vintage
aircraft restorer from BC, has provided a microfiche filled with rare drawings,
which the University of Manitoba is in the process of copying for the museum.
Neil Davidson and the Tiger Boys from Guelph, generously share their many
decades of experience working on Tiger Moths, and other antiques, from
around the world with us as we slowly uncover questions as the restoration
In preparation for the Tiger Moth rib building workshop, Gil Bourrier
created four jigs, two for aileron ribs and a 2-part jig for making wing
ribs. Gil began by fitting a stiff piece of cardboard over the spars and
wires so he could trace around the entire full-sized rib…with that classic
cambered lower edge that the Pietenpol builders recognized in their own
projects. He mounted this pattern on a sheet of plywood, covered the pattern
with clear plastic, and then strategically positioned spacers and clamps
to guide and hold the cross pieces and cap strips in place. The clamps
were round pieces of wood screwed onto the plywood so they could be rotated
to press the cap strip tightly into position.
Before beginning to build a rib, a collection of vertical and diagonal
braces need to be cut from 1/8” thick spruce. Braces are placed in about
seven positions along the rib. The brace for each position is a different
length and the angle of the cut at the top and bottom is unique…good idea
to cut a whole bunch simultaneously; so all the braces for one station
are identical. Spruce cap strips and gussets are also prepared in advance.
Once all the pieces are prepared, some two-part epoxy glue is mixed
and the braces are glued to the upper and lower strips placed in the 1st
jig. Cap strips are placed in the jig as spacers; cap strips aren’t glued
at this point. Once the glue is set, the partially constructed full-sized
rib is removed and placed in the 2nd of the 2-part jig designed to hold
the cap strips while they are being glued in position. A 2-part jig was
needed because the Tiger Moth rib design has a ‘T’-shaped cap strip with
braces added to both sides of the ‘T’. Participants took a close look at
the jig and actually tried fitting in the pieces to understand why everything
wasn’t just glued at the same time in one jig.
Larry Brown then helped point out some of the highlights visible in
the lower left wing currently being repaired. The all wood structure is
braced with steel drag and anti-drag wires. The wires are attached to an
adjustable eye with a hand spun coil of steel! This coil is made by hooking
the steel onto a lathe, spinning the lathe a few turns, and then slipping
it over the drag or anti-drag wire! The aileron control rod is moved with
a basic bicycle chain, with a handmade fitting attaching the chain to the
control cables. A bicycle sprocket is connected to the aileron control
rod, just like a pedal on a bicycle! It works extremely well, even after
70+ years of service!
A few of the ribs on the lower left wing were broken, splintered, or
loose. Over the last month or so, cap strips have been soaked in steaming
water, clamped to a mold and allowed to dry into the original shape of
the rib nose. Once the piece is dry, it is then glued into position, clamped,
and left until dry. This process is repeated, one rib at a time, and slowly
the wing is returning to its original airworthy condition. Straightening
and re-gluing has also been completed on the leading and trailing edges
of the wing and aileron.
Soon both these pieces will be ready for varnish and prepped for fabric.
About half way through the evening, we got to see the lower right wing,
fully covered with fabric, just as it was when it was de-assembled from
the fuselage last December. One of the goals for this event was to remove
the covering and begin inspecting this wing for damage that needed repairing.
Welding numerous knives, a marking pen, and camera; the entire team began
removing the fabric. Carefully cutting the hundreds of stitches, making
notes on the fabric, which will be used as a pattern when we begin recovering
the wing, and photographically documenting each section, slowly the original
Tiger Moth wing was uncovered.
The spar attachment fitting was removed. Following British procedures,
the nuts were ‘locked’ onto the bolts by bashing the last thread to prevent
the nut from falling off. To remove the nuts, the last thread has to be
cleaned up with a file and then the nut is easily removed with a set of
British Wentworth socket wrenches lent to us by Vic Préfontaine!
The lower right wing appears to need fewer repairs than the lower left
wing. The paint will be partially removed to check for any wood rot, hidden
fractures, and other abnormalities. With 20 people, it didn’t take long
to get a lot of work accomplished. You are invited to drop in to help prepare
this wing for any repairs and varnish bothy wings as we get them ready
for fabric. March 15th, Thursday, at 7:00 pm in the RAA Workshop Final
Assembly Building at Lyncrest, there will be a mini-fabric covering workshop…maybe
we’ll get to put the fabric on the Tiger Moth aileron and take one last
look at the original data plates, handwritten part numbers, and other original
documentation found beneath the fabric. One day, this Tiger Moth will be
back flying amongst the clouds on a beautiful summer day over the Brandon
airport. Yes, it is a two-person aircraft and the Museum is planning to
allow rides! Contact firstname.lastname@example.org
if you’d like to volunteer, we’re working most weekends from around 9:30
to Noon with some work done in the afternoon and some weekdays and evenings.
Check out the <tigermothrestoration.blogspot.blog>
or go to the www.RAA.ca website and click
on News to get to our weekly updated with photos and info on this exciting
“Let’s Keep ‘Em Flying”
Photos from the RAA Website