SCHOOL OF AIRCRAFT (PART 3)AIRPLANE FOR TWO. Most of aircraft fans, began his career in aviation with the construction of a single aircraft in the end come to the conclusion that such machines are extremely limited – to fly them only in calm weather; two-stroke engine is reliable, that does not allow the pilot to depart from the aerodrome; any significant cargo on such aircraft can’t be transported, and for learning single aircraft is not suitable.

As a result, many aircraft enthusiasts that have received the initial engineering and flight training on a single apparatus, begin to build a double. Examples of this could be quite a lot.
So wide popularity in this country has become “Dolphin” – one of the best training and sports aircraft, built in an Amateur club (Kronstadt) under the leadership of engineer P. Levine.
The airplane “Dolphin” is a monoplane with low wing and placement of the crew in the car. Currently, this arrangement is considered to be the most convenient for learning.
First time the plane took to the air with a 50-horsepower engine of the “Walter Mikron”, but he was weak and it was replaced by a 140-horsepower engine of the same company.
The creators of “Dolphin” chose a very rational dimension of the plane in which the main parameters -the specific load on the wing (50 kg/m2) and the specific load capacity (4 kg/HP) – provide easy piloting technique, relatively low stall speed and, consequently, low takeoff and landing speeds. At the same time the installed power of the machine is sufficient to perform aerobatics.
Double sport plane
Double sport plane “Dolphin”:
wing area – 12,69 m2; empty weight – 456 kg; takeoff weight – 670 kg; weight of power unit – 125 kg; the engine weighs 102 kg; maximum speed – 200 km/h; rate of climb at ground – 4.8 m/s; range of flight of – 200 km; takeoff run – 140 m; mileage: 110m

Double plane
Double plane “Troika” B. Pobutovogo (Saint Petersburg):
the area of the upper wing – 10,8 m2; lower wing – 9,7 m2; the installation angle of the upper and lower wing – 6 degrees; installation of stabilizer angle of + 2 degrees; empty weight – 470 kg; takeoff weight-670 kg; in-flight alignment of 23% is equivalent to SAH; maximum speed – 150 km/h stall speed 65 km/h; rate of climb at ground – 2 m/s; range – 160 km; takeoff run – 120 m; mileage: 80 m; operating overload – 3

Solid metal construction “Dolphin” is simple and rational. The fuselage is of the monocoque type consists of thirteen frames, four stringers and dural covering. The front frame is the same and the firewall, riveted two aluminum sheets with an asbestos gasket between them. Single-spar keel and dvuhkonturniy the center section is made integral with the fuselage. All the details of cladding made of D16T sheet thickness 0,6 – 0,8 mm.
Detachable wing – odnalezienie, with an oblique auxiliary spar in the tail part, made using parts from a decommissioned glider KAI-11. The toe bracket to the spar has aluminum casing and takes all the loads from torsion of the wing. The tail part of the console is covered with canvas. This design provides the minimum weight of a cantilever wing.
The relative thickness of the airfoil at 15.5 per cent. The wing has slotted flaps and ailerons. The design of the ailerons and flaps of a double-seat, single-spar, with fabric covering. The flaps are manually driven and deflected at 15 degrees at take-off and 58 degrees on landing.
All-moving horizontal tail (no Elevator), the design is similar to the wing with a servo tab, amplifying the load on the control knob to the desired value. Deflection up to 12 degrees and down 10 degrees.
A control plane coupled, wiring to the elevators and to the steering wheel direction is made by cables with a diameter of 3 mm, and the ailerons and rudder areas – rigid rods.
Design aircraft
The design of the aircraft “Dolphin”:
1 – metal propeller; 2 – bow-spring chassis with sa-variantarousal wheel; 3 – the main spring suspension; 4 – fold lamp; 5 – anti-flatter rocker; 6 – rocking of the control system stabilizer; 7 – safety tail wheel; 8 – engine; 9 – retractable air inlet of the fan; 10 – tank; 11 – the main wing spar; 12 – auxiliary rear wing spar; 13-sliding window light; 14-the hatch of the battery compartment; 15 – bensinger; 16 – trimmer

Aircraft design
The design of the aircraft “three”:
1 receiver air pressure; 2 – step (left only); 3 – V-shaped strut of the wing; 4 – engine; 5 – metal propeller; 6 – cable of the actuator of the rudder; 7 – struts stabilizer; 8 – inlet oil cooler; 9 – liquid-gas shock absorbers, suspension; 10 – spar wing; 11 – drooping ailerons; 12 – flap; 13 – tank; 14 – oil cooler; 15 – a spring damper in the transaction control front

Landing gear fixed landing gear, leaf spring, made of spring steel 65С2А. Original looks like the front landing gear, made from bar steel of the same brand.
The wheels of the main landing gear – brake, are made of standard non-braking wheels size 400×150 mm. brakes – mechanical.
The basis of the power plant of the aircraft – a 4-cylinder aircraft engine “Walter Minor-4”, equipped with metal propeller to be modified on the ground step. The engine shall be started using an electric starter.
The equipment of the “Dolphin” included the attitude indicator, turn and slip, and compass small radio station that allows you to operate even in adverse weather conditions. The pilots ‘ seats have a simple design, but allows use of back strap parachutes. Originally performed by big canopy with two easy-open up the doors (both on the ground and in flight), and if necessary, they are reset, ensuring the safe evacuation of the aircraft by the pilots in a critical situation.
According to its flight capabilities “Dolphin” is almost not inferior to the sports training aircraft Yak-52, and in some respects superior to the production car. At one of the gatherings SLA “Dolphin” was awarded the special prize of the Central Committee DOSAAF as the best training aircraft.
Good flight data had another double plane created by the St. Petersburg driver B. Khomutovski. By the way, it was the third aircraft designer-an Amateur – the first two were single and too subtle.
To build a double car took several years -and this despite the fact that Pobutovogo there were young assistants. The project provided that the aircraft is a monoplane, however, the limited size of the “factory” has forced the designer to make the plane a biplane instead of a single large wing span had to install a couple twice smaller.
And yet – Homutovskiy equipped aircraft pusher propeller – to do this, the tail part of the fuselage had to make a double.
The first machine was installed engine from the car “Volga”, but he was too heavy. More appropriate was the 115-strong “Walter-Minor 4” -with it, the aircraft demonstrated a very decent flight characteristics. The machine was easy to operate, reliable and undemanding in operation. Its maximum speed is 150 km/h, climb rate – 2 m/s.
Double training aircraft M-3 designs V. Makhova
Double training aircraft M-3 designs V. Makhova:
wing area – 21 m2; empty weight – 500 kg; take-off weight is 680 kg; fuel capacity – 40 l.; cruising speed – 100 km/h; rate of climb 6 m/s; flight duration – 2.5 hours

Aircraft M-3
Aircraft M-3
Double training-sport aircraft
Double training-sport aircraft “Leader”:
wing area of 11.3 m2; wing profile – NACA-23015; empty weight – 580 kg; takeoff weight of 800 kg; the maximum speed of 250 km/h; stall speed is 100 km/h; rate of climb is 5.6 m/s

The Plane “The Leader”
Double plane
Double plane “Exotic” design brothers Mineikis (Lithuania):
the wing area is 16 m2; empty weight – 356 kg; take-off weight of the aircraft with two pilots – 511 kg; maximum speed – 130 km/h, stall speed – 60 – 70 km/h; rate of climb is 5 m/s

Double plane
Double plane “Duet” design Zinovkina A. (Tver):
empty weight – 525 kg; takeoff weight 750 kg; the maximum speed of horizontal flight – 150 km/h; stall speed 75 km/h; rate of climb at ground – 3.5 m/s; run -150 m; mileage: 100 m; range of operating overloads from +3 to -3

Training aircraft
Training aircraft “Tomahawk” company “Piper” (USA):
the engine “Lycoming” with a capacity of 112 l/s; wing area – 11,6 m2; take-off weight – 758 kg; empty weight – 483 kg; the maximum speed is 202 km/h; stall speed of 87 km/h; rate of climb is 3.5 m/s; range of flight – 866 km; takeoff run of 250 m; mileage: 180 m

In General, the Czech engines of the “Walter Minor” is very actively used by aircraft enthusiasts during the construction of a double aircraft. So, at the time in Voronezh by a group of enthusiasts led by I. Pivovarova was built strut-braced high-wing monoplane with “Horizon” with this motor. In the late 1980-ies Moskvich V. Makhov created the all-metal high-wing monoplane M-3, in the manufacture of which used components and assemblies of the glider KAI-12 Primorets. The basis of the power plant of his car – 140-HP engine M-332. And one of the SLA caught everyone’s eye all-metal high Lider, created by a team of Amateur OKB “Flight” (Samara). This aircraft, fitted with a 140 horsepower 4-cylinder aircraft engine M-332, parameters close to the optimum mass plane for the initial training. Crew members located in the cockpit in the car.
Such double planes thousands of series available in the West, and in the production are more than 20 different models. So, very popular among aviators-lovers are American “Cessna-152” and “Tomogavk” company “Piper”. However, along with these all-metal machines successfully produced and more simple strut vysokopilya with cloth paneling – “champion” and “decathlon” company “Bellanca” and “KEB” company “Piper”. These aircraft are very simple in design, cheap, made of locally available materials and often made by Amateurs on the finished drawings themselves.
In addition to these machines, the Amateur designers of Western countries developed many variants of the double planes of differing design, aerodynamic schemes and power plants. The most popular and already classic now can be considered a cantilever diskoplana like our “Dolphin”. From machines of this type can be distinguished as the most popular American all-metal T-18 “Tiger” company “Trop” and the canadian “Zenit”. These machines are aircraft enthusiasts are building original drawings themselves. I want to draw attention to the extremely simple all-metal construction of the aircraft “Zenit” – one of its main advantages is that it can be adapted for manufacture in a small Amateur Studio.
Double vysokopilya with
Double vysokopilya with “tight” layout of the cockpit:
A —”Blue bird-10″ design E. Shevchenko:
the wingspan is 8.4 m; wing area – 10.4 m2; take-off weight – 328 kg; engine power – 62 HP; diameter of the propeller – 1050 mm; pitch of screw is 400 mm; static thrust of 115 kgf; maximum speed – 135 km/h stall speed 65 km/h; rate of climb at ground – 2 m/s
B – training and aerobatic aircraft decathlon (USA):
engine power – 150 HP; wing span – 10,15 m; wing area – 1552 m2; empty weight – 484 kg; takeoff weight of 748 kg
In – plane “Cab” (United States) and the layout of its cabin

“Blue bird-10”
Airplane Decathlon
Aircraft Decathlon
The wing and horizontal tail of “Zenit” stenosis does not have all the trim is made of sheet of aluminum, however, any surface with double curvature in the plane there. So in the manufacture of parts from sheet using only one technological process – flexible. The designer of the aircraft was able to do without the parts that require drawing. So, for example, slabs of ribs have a characteristic petals, which, when the limb form a flare – it can help in the Assembly of the rib with rivets connects to the hull.
The sides and bottom of the fuselage Zenit – flat, which is a very simple and rational solution that can work even without traditional frames and without the slipway for Assembly. By the way, about the same “cut” the fuselage “Dolphin”.
From aviators enthusiasts often we hear that planes with wings without constriction, with flat sides and bottom of the fuselage looks ugly. Of course, each designer has their own idea about the aesthetics of the aircraft, however the design of “Zenith” and “Dolphin” completely refutes this view. This is corroborated by the appearance of some light aircraft company “Piper” that has almost the same configuration of the wings and fuselage, and thus are samples of remarkable aviation design. Moreover, at the time, the specialists PASS the “Piper” who have studied the stall light aircraft, came to the conclusion that such a “square” tail part of the fuselage helps to improve spin characteristics of the aircraft.
“Cut” blank wing “Zenith” – another example of a simple rational design solutions: technical, beautiful, and, as shown by aerodynamic blowdown, the aerodynamic quality of the plane so the wing is slightly higher than that of the device with the wing, the edges of which have a rounded shape.
Another simple and rational design solution embodied in the “Zenit” – suspension of the ailerons and flaps on the so-called “piano” hinge. True, these ailerons is no aerodynamic compensation, but at low speeds it is not required. Well, aerodynamic drag of the ailerons with the suspension less than that of the ailerons with a traditional suspension, the effectiveness of ailerons for the aircraft of this class is enough.
Double Amateur aircraft
Amateur double planes with car-location pilots:
A – airplane “Fun fly” (Switzerland):
engine “Rotax-503” power of 53 BHP with a gearbox (gear ratio – 0,326); the diameter of the propeller 1.6 million m; wing area -17,5 m2; empty weight – 174 kg; takeoff weight of 375 kg; fuel capacity – 48 l; maximum speed – 120 km/h stall speed 45 km/h; rate of climb is 5 m/s; run-up and mileage – 50 m, ceiling – 5500 m; range – 450 km; the range of operating overloads from +10 to-10;
B – plane T-18 “Tiger” (USA):
engine power – 125 HP; wing span – 6.35 m; wing area-8 m2; maximum speed of 273 km/; the stall speed is 100 km/h; the range of 920 km
In the Zenith plane (Canada):
engine power – 100 HP; wing area – 10 m2; empty weight – 395 kg; takeoff weight of 650 kg, the maximum flight speed of 240 km/h stall speed (with flaps) – 85 km/h; stall speed (no flaps) – 95 km/h; rate of climb – 4.5 m/s; range of flight of 600 km; ceiling – 4,600 m

The Plane
The Plane “Piper “Cab”
In the scheme of “Zenith” noteworthy is the use of all-moving fin and stabilizer, not the usual rudders and height. Although the design of feathers in this case is much simpler, but nevertheless, from the point of view of stability and controllability is not the best decision.
The parameters of all these double planes are very close. Thus, the specific load on the wing from 45 to 60 kg/m2 takeoff weight of 600 – 750 kg. As a rule, aircraft used simple flaps with manual or electric drive. Engine power – 100 -150 HP, providing machines rather high performance that allows you to perform aerobatics. Moreover, this capacity makes it possible to use on the plane wing to the reduced area, to compensate for this relatively high load on it. Such a device is becoming less dependent on adverse weather conditions – strong winds and atmospheric turbulence.
The creation of a twin plane and possibly on the basis of the engine less power – these cars also attract the attention of Amateur designers. Read more about these aircrafts readers learn to “lesson” our “school.”

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