Peter Roake - PBY Catalina

Peter's latest project is a Consolidated PBY Catalina Flying Boat. Although there are kits available, Peter prefers to scratch-build. He started this build by purchasing a 1/72nd plastic model. He then used the plastic components as templates, drawing round their outlines on a piece of graph paper. Once he had completed the basic wing, tail and fuselage, he transferred his sketches to a larger piece of hand-drawn graph paper. He chose to scale the new graph paper at 5:1, since he wished the resulting wingspan to be around 85". Power would be supplied by 2 x .30 four-strokes and his target weight is under 7lbs. Some idea of the work involved can be gained from the photos below. They show his original sketch and his scaled-up, home-drawn graph paper which he used as his construction plan.

The small white paper is the original piece of graph paper containing the drawn outlines of the major components. The larger piece is the scaled-up graph paper where Peter drew his full-size plan which forms the build guide.  

As a true scale builder, Peter's first major problem centred on the undercarriage. It was never his intention to operate the model from water but he did wish the model to have a retractable u/c so that it would look right when airborne. He spent a great deal of time trying to design a workable main gear installation which replicated the full size. After much trial and effort, (including a visit to Duxford to look at a real Cat) Peter established the basic geometry of the design by using a moveable template which he could then fine tune to ascertain the correct positions of hinge points as well as the required lengths of the gear struts. The following photographs show the "gizmo" Peter devised to perfect his design and the manner of gear operation.

Having used his model template to establish the precise locations of the pivot points and lengths of the u/c legs, Peter then incorporated the u/c within the hull of the model. The main gear is counter-balanced by a spring and thus the retract servo does not have to "lift" the weight of the main-wheels during retraction or extension. The nose-gear was relatively straightforward, with the gear doors being operated by an elastic band. Peter has now built the lower hull, which incorporates the central pylon to which the main wing will eventually be fitted, as well as the retracting gear installation. The detail is quite extraordinary, as can be seen from the photographs, while the complex arrangement of levers and mirrors involved in the gear operation are quite dazzling! The spring counter-balance can just be seen in the photograph, as can the intricate connecting lever arms.

The sequence of operation of the gear is quite superb and some idea can be gleaned from the following

 sequence of pictures:

 That is the build so far. Watch out for updates as this project continues.