Tom Bennett - 'Retiree Corner' article

Tags:  candib papers 
Author: Don Wilson
Published: Jul 26th 2009
Updated: 4 years ago

[Webmaster’s Note:  This story was re-keyed from a poor-quality fax of a page from the 3 September, 1995 issue of de Havilland’s publication “Plane Facts”  sent to CANDIB by Tom following his attendance at a CANDIB meeting. The specific article was from the “Retirees’ Corner”].

Basement project turns up in Museum of Science and Technology

By Tom Bennett

Imagine my pleasure and surprise upon finding one of my hobby projects in the Museum of Science and Technology in Ottawa. The long-lost model of Bras D’Or, the forerunner of one of de Havilland’s engineering achievements has been found. In 1960 I was privileged to become a member of an 11-man engineering team which was studying the feasibility of designing an ocean-going hydrofoil capable of tracking and destroying modern submarines. It was my responsibility to prepare the overall layouts of the design. The concept fascinated me and I decided to construct a scale model in secrecy.

With the help of Tom Mann and the hindrance of my rascal pet squirrel, the six-foot plaster mould took shape. During the many nights of work on the project, the thought of making this a working model developed. And then the fun began.

The challenge of designing a transmission and hydrodynamic considerations brought Barry Davis (project hydrodynamics) and Vesty McGarvey (development shop foreman) into the secret fold. A model airplane diesel engine driving through a flexible coupling to a 90o bevel gear box was selected as the power source. The gear box bifurcated the drive to 3/16” diameter drive shafts down the two foil struts. The drive shafts were connected to right angle windy drill gear units in the pods 12 inches below the gear box. Vesty solved the problem of starting the engine with a portable 12-volt automotive starter motor and battery and a V-drive pulley was welded to the forward face of the gear box. After 18 months of hard work the model was launched and our troubles began. The engine overheated, the flexible coupling failed and the propeller required redesign. We tackled these problems with enthusiasm, confident that the model would work. A single-channel radio was purchased and a complicated mode switching system was designed and fitted to control the model. This was a vast improvement over our original method of tethering it with a fishing line. At this point our secret was revealed. Dick Becker, manager of the hydrofoil project, got wind of our clandestine activities and, after rebuking me for contravening the oath of secrecy, requested a demonstration of the model.

Barry, Vesty and I arrived at Lake Couchiching before the appointed time to do a trial run. The model performed well until it dropped off its foils, leapt up and sideswiped a boat before responding to its slow-acting control system. Becker and his seniors arrived in time to see us trying unsuccessfully to repair the damage. At that time, de Havilland provided funds for a 10-channel radio and after simplifying the control system our model functioned perfectly.

De Havilland purchased the model and Reg Corlett made a superb movie of the model in action. This movie was used as part of the feasibility study presentation made to the Canadian government. The Royal Canadian Navy requested that the model be displayed at the Canadian National Exhibition the next summer. The diesel engine was exchanged for an air motor and the model ran in circles around a 50-foot doughnut-shaped tank of water. This was the last time I saw the model until my recent trip to Ottawa 28 years later.

Last year, Garth Wilson of the Museum of Science and Technology contacted me requesting information about the Bras D’Or. During our discussions he mentioned that the museum had a model of a hydrofoil but was unaware of its origin. In June, 1991, I travelled to Ottawa to view the model and, to my delight, discovered that it was my basement project.

There is a possibility that the model will be restored and put on display as a replica of the full-size ship – de Havilland’s contribution to hydrodynamic technology.

As a footnote to the above, design and production of the Bras D’Or proceeded. In 1968 she was launched and proved to meet all design specifications. But technology overtook her. She now sits, unheralded, on the banks of the St. Lawrence River at the Bernier Maritime Museum, L’Islet-Sur-Mer, Québec. But that’s another story.