Macchi-Castoldi MC 72 (oz11795)

About this Plan

Macchi-Castoldi MC-72. Rubber scale model floatplane racer.

Quote: "Building the Macchi-Castoldi Seaplane. Data and Plans from Which You Can a Create a Cleverly Designed Model of the Fastest Airplane in the World. By C.L. BRISTOL.

THE 'Red Bullet of Italy,' more properly known as the Macchi-Castoldi 72 and holder of the world's speed record at 423.7 mph, provides the builder of flying scale models with new and interesting material. Two propellers in close tandem arrangement and revolving in opposite directions provide a power unit that is without torque, a feature of considerable value in the model as well as the large sea-plane.

The builder who studies all drawings carefully and reads all instructions prior to beginning work, will have no difficulty in making this model. Its construction is entirely conventional excepting the power plant, in which the rear prop is driven from the rear end of the rubber motor by means of a balsa driving tube and hollow propeller shaft, which in turn acts as a bearing for the front prop of conventional structure.

Plates 1 and 2 joined together at the section lines provide a side view fuselage layout, with all stations shown in cross section. The fuselage is made entirely of balsa pieces of the size shown in drawings. Two sides composed of the longerons and all uprights and diagonals between, should be assembled and joined together. Top cross members B, C, D and Q are identical in size and shape and should be sanded together as in rib construction. Observe the heavy lower cross member at the point of greatest stress, section C-C. It is important that this piece be carefully cut and securely cemented in place as it maintains body alignment.

Spinners S and S' should, for accuracy, be lathe turned and center drilled as one piece, cutting them apart afterward. They are also of balsa and may be shaped by hand where the above equipment is not available to the builder. Propeller blades are cut and served separately, see Plate 3, and mounted to these spin-ners on bamboo plugs at an angle of 30 degrees. The balsa nose block is shown in side, top, front and rear elevations. It may be hand-carved and must tit the rear spinner S' in front and the bulkhead A-A at the rear, at which point it is drilled for short pieces of hardwood dowels. These plugs, ce-mented only to the bulkhead, facilitate easy removal of the nose block, motor, etc.

The driving tube for the rear propeller can be made from a sheet of 1/32 in balsa by soaking in hot water and rolling it around any suitable piece of dowel, pipe or tubing. When dry, the seam can be cemented and the ends trimmed to the correct length. This tube is provided with round end plugs, P and P' in drawing, and attached to the hollow bearing JKJ' which is shown assembled at top K. The pieces I, J and J' are of sheet brass .45 in thickness, while K is of brass tubing 1/8 inch outside diameter. The center hole in I should fit K, and the plates J and J' are drilled to fit the front prop shaft L.

Assembly of these parts should be as follows: solder J to K, centering carefully, slip spinner S' and bearing I on K, placing a fibre washer behind I. Next solder J' in place and cement to the plug P. In the rear end of this assembly, the pin X and washer X' form a free bearing which is attached to the fuselage by means of the cross-piece V', see drawings 2 and 4. V' of pine or hard balsa, slides across the fuselage between the side blocks V and is removable. The piece U is a rear motor hook of music wire and is secured to the tube Tat the plug- P'.

In assembling the motor, lace three loops of 1/8 inch flat rubber through the rear hook U and tie the ends in a square knot, making the loops about 11 inches long. By means of a long wire hook, pass the rubber through the tube..."

Quote: "Attached are the plan, article and a pic of the Macchi Castoldi MC-72 plan from Universal Model Airplane News September 1934. It has a working contra-rotating prop and a 22 in W/S. I cleaned up the plan and made a complete plan for both wings and stabilizer halves."

Direct submission to Outerzone.

Supplementary file notes

Article.

Corrections?

Did we get something wrong with these details about this plan (especially the datafile)? That happens sometimes. You can help us fix it.
Add a correction