Research

Curtiss JN-4 “Canuck”

Curtiss JN-4 “Canuck”

The specimen as obtained by the Museum in 1962 was basically complete. The wings still had the original 1918 fabric on them, but all other components had been stripped. It had been in civil use and the instruments were not original except for the oil pressure gauge; other items were missing or damaged.

When the specimen was obtained, the Museum had no workshop capable of housing it. Nevertheless, because of its historical importance to Canada, it was felt that a way must be found to start its restoration. A narrow area at the back of the Museum at Uplands wa made available, and while most components were carried in through the twisting hallways, the fuselage had to be hoisted in through a second-storey window.

Curtiss JN–4 “Canuck”
A new turtle deck for the rear fuselage is being assembled by Arthur Walker for the Canuck.

After being displayed at Rockcliffe on Air Force Day in June 1962, the specimen was trucked to the Museum and restoration started. We decided to restore the machine with the fabric removed from one side as a result of favourable comments when it was displayed with its structure visible. At that time no drawings were available to the Museum, but a stress report contained some useful information and a large number of photographs proved invaluable. A large-scale Canadian Aeroplanes made model showing all structure in detail also provided useful information.

The fuselage was completely disassembled and restored in two stages. First, the portion from the rear cockpit aft was done, and then the forward section. All metal parts were cleaned and repaired or plated as required. All wood parts were cleaned and varnished. Only three wood parts required replacing-the right horizontal seat bearer and the large left upright member at Station 3, along with the transverse support for the engine bearers at that station. During this work the American serial 39158 was found on the upper right longeron in the rear cockpit, establishing the original identity of the machine for the first time.

The cockpit flooring was cleaned and revarnished, all flight controls were removed and re-plated, and a new front control stick socket and stick were made to replace the crude ones made by some previous owner. New engine cowling panels were made to replace the badly worn and cracked original ones. The rear fuselage turtle deck, of later design and in very poor condition, was replaced by one of earlier design based largely on the detailed model.

Curtiss JN–4 “Canuck”
The complete flight control system is shown here reassembled on the cockpit floor boards and ready to be placed in the aircraft.

Curtiss JN–4 “Canuck”
This photo provides a good view of the wing bracing and aileron control cables. The aileron control system was unique to the Canuck in the JN-4 family and is an excellent and reliable recognition feature.

A new instrument panel was made to the correct layout, and all original-type instruments, lights, etc., were located except for the airspeed indicator for which a dummy was made. New throttle controls were fitted in the front cockpit; Deloro Stellite kindly provided the casting. The seats were repaired and re-upholstered. A correct style of seat belt was donated by Ed Carlson of Spokane, Washington, which served as a pattern for new ones and all-new webbing was installed in both belts, with needed castings again made by Deloro Stellite.

The tail surfaces were generally in good condition. The wood members required only minor repairs, cleaning and revarnishing, and the tubular members were treated internally with linseed oil as apreservative. New elevator trailing edges were required due to corrosion, and as the Museum could not form them in the required lengths, Canadair Ltd. generously supplied them.

The undercarriage required only cleaning and refinishing, but the spoked wheels were rusted, and to avoid complete disassembly Canadair kindly cleaned them as a unit in their ultra-sonic cleaner.

The wings, in general, required only minor repairs. However, the aircraft had been in an accident at some time, which resulted in the root fitting of the left upper front spar being pulled out of the spar and the end box rib being badly damaged. As only very crude repairs had been made originally, spar repairs and a new end rib were required. All- new trailing edges were required. All ailerons were warped so four new ones were made.

The OX-5 engine obtained with the machine was overhauled and placed on separate display, and a second OX-5 was overhauled and placed in the aircraft. A donated Canadian Aeroplanes made propeller was refinished and installed to replace the American made one obtained with the machine.

As doping was not permitted in the Museum building, the covering and doping were done under contract by Personal Plane Services to the Museum's specifications. The method of applying the fabric to the JN-4(Can.) fuselage was unique and it took considerable research before all its details were determined. The aircraft was finished as a machine of the 85th Canadian Training Squadron bearing its Black Cat insignia. The colour of the cowling was researched and a particular shade of green was selected as specified by a former senior Canadian Aeroplanes employee. However, it has since been determined that this colour is incorrect, and some day the specimen will be refinished in khaki brown. The restoration was completed in May 1964.

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