“PIPER”: A CONTOUR COPY

Competitions of different rank showed that as prototypes for the manufacture of contour models are used only a dozen types of aircraft. And to participate our aeromodelling circle in the next competition, it was decided to make a model rare prototype. Our choice fell on PIPER CAB, one of the most successful light aircraft, produced in mass quantities since the pre-war (1935).

 

Aerodynamic design of this aircraft — strut-braced high. The two-spar wing with V-shaped braces that compensate for not only bending but also twisting moment of the wing. These wings are for airplanes-monoplanes are the most easy and simple.
 
 
The plane-vysokoplan PIPER CAB
The plane-vysokoplan PIPER CAB
 
Geometry cord contour model polyopia aircraft PIPER CAB
Geometry cord contour model polyopia aircraft PIPER CAB
 
Table of the control section of the airfoil
The table control section of the airfoil
 
The scheme of constructing the profile of the wing
The design of airfoil
 
The wing spars — a wooden, box-like structure. Ribs were made of bent aluminum profiles. The covering of the wing, except for a narrow plywood sock, white.
 
The fuselage truss, welded thin-walled steel pipes. Linen lining, fastened on the wooden stringers that are installed on a steel frame to give the fuselage a smooth streamlined shape.
 
The cabin is designed for two pilots sitting one behind the other, located in the front part of the fuselage. The dashboard was equipped with only the working place to the front of the pilot. Cabin entry is through double doors in the starboard side of the fuselage.
Empennage simplest design. Frames, keel, stabilizer and rudders were welded of steel pipes, after which the knots tight fitting cloth. The strength and stiffness of the tail was provided by braces.

 
Landing gear: tubular, welded. Depreciation was carried out with a rubber cord, braided on the middle brace. Side flat farm chassis to reduce aerodynamic resistance tight fitting cloth.
 
The aircraft was equipped with a minimal set of navigation equipment, consisting of a speed indicator, altimeter, palukanas, tachometer, and temperature sensors to the cylinder heads of the engine and oil temperature.
 
Layout models
The layout of the model:
 
1 — mount the fuel tank (a self-tapping screw d3); 2 — fastening strut to the wing (M2 bolt with nuts and washers); 3 — simulated light (organic glass, sheet s4); 4 — top and bottom outlines of the fuselage (cedar, 12×7 rack); 5 — internal bracing of the rear fuselage (cedar, rail 10×4); 6 — frame of Kiel (cedar, rail 10×5); 7 — rib of Kiel (cedar, rail 5×5); 8 — flange of the rudder (wakaka of seven layers of spruce veneer s0.8); 9 — rib of the rudder (cedar, battens 5×5); 10 — frame rudder (cedar, rail 10×5); 11 — tail wheel (plastic, d20); 12 — tail wheel (wire OVS d1,5); 13 — pylon rudder (aluminum, sheet s2); 14 — stringers of the rear fuselage (cedar, rail 4×4); 15 — fastening struts to the fuselage (M2 bolt with nut and washers); 16 — mount the wing panels to the fuselage)’ (steel, stud M4 with nuts and washers); 17 — main landing gear (aluminum, sheet s2); 18 — wheel (“Thermals”, d50);19 — the forward fuselage (plywood s12); 20 — fuel hose; 21 — plate (plywood s3); 22 — engine KMD-2,5; 23 — motor mount (birch, 15×15 bar); 24 — control rod; 25 — fuel tank 26 — root rib (cedar s8, lined with plywood s1,2); 27,32 — spars (pine, rail 8×4); 28 — ribs (plywood s1,2); 29 — of the rear edge (cedar, rail 10×5); 30 — brace; 31 — front flange (lime, rake 6×6); 33 insert (GRP); 34 — end rib (plywood s1,2); 35 — wing tip (Vileika of seven layers of spruce veneer s0,8); 36 — mounting brackets struts (aluminum, sheet s2); 37 — mount the main landing gear (MOH bolt with nut and washer); 38 — bracket struts to the fuselage)’ (duralumin, area with shelf s2); 39 — mount bracket rocking to the fuselage (M4 bolt with nut and washers); 40 — bracket with rocker control; 41 — rib rudder (cedar, battens 5×5); 42 — joint Elevator (fishing line d0,15, braided “eight”); 43 — the leading edge of the stabilizer (Vileika of seven layers of spruce veneer s0,8); 44 — rib stabilizer (cedar, battens 5×5); 45 — torsion (wire OVS d2); 46 — rear edge of the stabilizer (cedar, rail 10×5); 47 — the leading edge of the Elevator (cedar, rail 10×5); 48 — the trailing edge of the Elevator (Vileika of seven layers of spruce veneer s0,8); 49 insert (Linden); 50 — wheel axle chassis

 
The technical characteristics of the contour model-copy aircraft PIPER CAB
 
Technical characteristics of the aircraft PIPER CAB: length 6710 mm, wingspan 10 740 mm wing area 16,55 m2, engine power 65 L. E. takeoff weight 554 kg, the empty weight of 339 kg, a maximum speed of 137 km/h range 400 km, a ceiling of 3,500 m, the run 107 m, mileage is 125 m.
 
In our experience, PIPER CAB great prototype models of any class thanks to a successful aerodynamic design of high-wing monoplane with the wing of a large area. The last quality will be able to build models from abundant materials without the use of inaccessible to the members of balsa.
 
Offer cord model-polyopia this plane — spectacular in flight, durable, volatile, it is available for making the members of the second year. The construction of contour “Piper” in our group is from 1997. Built twelve variations of this model, observations on their strength and manageability almost was not. With a good engine KMD-2.5 model is easy to perform turns and rolls even when the fresh wind.
To begin work on the preparation of the model suggest of the fuselage. The nose part is cut from high quality 12 mm plywood, the Central is a flat farm, a laminated cedar top and bottom contours of slats section 12×7 mm, internal bracing — strips of a cross section of 10×4 mm. on Top of the struts are mounted, the stringers of the cubes cross-section of 4×4 mm. Assembly of the fuselage is carried out by using epoxy glue.
 
After curing of the binder in the Central part of the fuselage zashlifovyvayutsya — wedge thickness is 12 mm in the area of the wing and 4 mm for the keel, and the tail section are glued plate made of plywood with a thickness of 1.2 mm with a groove under the stabilizer. Next on the forward fuselage glued the lining of 3 mm plywood to the right with the groove under the engine and left without a groove. Motor mount is done from a pair of birch sticks thus ensuring that Vegas engine — three degrees in the outer (portion of circle) side.
 
Fuel tank
Fuel tank (shell — tinplate s0,3, tube power supply, gas and drainage — copper, 4×0,5)
 

Control rod Elevator Assembly
Control rod Elevator Assembly:
 
1 — pull (birch, rake 6×6); 2 — Oconto-ka (wire OVS d1,5).
 
The management node model: 1 —bracket (made of anodized aluminum, the area with abrasive s2); 2 — hinge control arms of (MZ bolt with nuts); 3 — rocking control (duralumin, sheet s3)
The host management model:
 
1 —bracket (made of anodized aluminum, the area with abrasive s2); 2 — hinge control arms of (MZ bolt with nuts); 3 — rocking control (duralumin, sheet s3)
 
Strut Assembly
Strut Assembly:
 
1 — brace (birch, 8×6 rail); 2 — site of attachment of the brace (made of anodized aluminum, sheet s2)

 

Simulation of the lamp is a plate of organic glass thickness of 4 mm. For fixing it in the forward fuselage at the seam hollows out a groove width and a depth of 4 mm, and at the bottom of the “lantern” nastelivaetsya horizontal holes with a diameter of 2 mm for glue, after which the plate is inserted into the groove of the fuselage and fixed it with epoxy glue. You should warn young designers that the lamp should be replaced only after pre-Assembly of the model and verify its symmetry and regularity of arrangement of the wing and struts
 
The wing model has a PLANO-convex profile with a relative thickness of 12%. Spars from pine slats with a cross-section 8×4 mm, front edge — lime block, cross section of 6×6 mm, back edge — the cedar rail section 10×5 mm. Ribs cut out of plywood with a thickness of 1.2 mm, the location of the ribs along the span of the wing corresponds to their location on the plane prototype. The root rib consoles — cedar, 8 mm thick, lined on the outside of the plywood plate with thickness of 1.2 mm without cut-edges and spars. Wingtips is laminated on the mandrel plywood of seven layers of spruce veneer in the thickness of 0.8 mm using epoxy resin. Console attached to “the lantern” a pair of threaded studs M4 with nuts and washers, which in the root rib and “light” holes are drilled with a diameter of 4 mm.
 
The struts are made of birch slats 8×6 mm oval section; the attachment — pasted on the epoxy into the slots in the braces of strips of 2 mm thick duralumin. mounting Brackets to the wing struts are cut from 2-mm sheet of aluminum; the spars are fastened with bolts with thread M2. Brackets-angles of attachment of the struts to the fuselage is carved from a corresponding aluminum profile with flange thickness of 2 mm to the fuselage they also are fastened with bolts with thread M2 with nuts and washers.
 
The keel, rudder, stabilizer and elevators — matched, made of cedar. The trailing edge of the stabilizer, the leading edge of the Elevator and rudder, as well as the contour of the keel from the Reiki section 10×5 mm; cross-set tail — bars cross-section of 5×5 mm. the Rudder is mounted on the tail with pins of mild steel wire (from an ordinary paper clip) — this allows you to change the angle of deflection at the test flights of the model. Halves of the Elevator are connected with a torsion bar of hard steel wire, allied with a diameter of 2 mm. Loop of mounting the elevators are made of fishing line 0.15 mm in diameter, braided on the stabilizer and rudders “eight”.
 
The main landing gear cut and bent sheet of aluminum with a thickness of 2 mm. To the fuselage they are mounted a pair of MZ bolts with nuts and washers. Wheels with a diameter of 50 mm — type “Thermals”, axis — threaded rods MH, mount wheels with nuts and locking their nitro Tail wheel plastic, with a diameter of 20 mm; the front of the wire type, allied with a diameter of 1.5 mm is fixed in the fuselage with epoxy glue. The wheel is fixed on the front soldered to it a metal washer.
 
Control system — standard for cord models of this type. Control rod connecting the rocker with the horn of the Elevator is a round pine rail with a diameter of 6 mm with a wire okoncovke with a diameter of 1.5 mm. the mounting bracket of the rocking — dural “area” with a wall thickness of 2 mm; the fuselage it is attached with M4 bolts with nuts and washers. The rocking chair — sheet duralumin of a thickness of 3 mm.
 
The fuel tank model with a capacity of about 60 ml — tin, soldered to the fuselage it is attached with two screws-sa-moresome with a diameter of 3 mm.
 
The finish is fining her macalintal paper on Amalia and colouring by nitroenamels in accordance with the color of the prototype aircraft.
 
I must say that the model turned out to be surprisingly strong. One of twelve copies are made by us after fifty flights, we removed the trim and checked all the glue joints the strength of the structure as a whole. As it turned out, the frame had no cracks, no broken glue joints.
Vladimir KOZIN, head of the aeromodelling circle, Magadan

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