Technic Airplane With Power Functions and Pneumatics

I have been trying to build an airplane from LEGO for some time and now I was able to build one with all the functions that I had in my head. In my opinion, this model, if made from properly coloured parts, could be a nice ornamental piece in an apartment but at the same time it's something that you can play with.

 

Electronic system controls: Slotted flaps, Slats, Speed brakes/Spoilers, Trimmable horizontal stabilizer, Rudder trim, Thrust reversers, Lights and Retractable landing gear with gear doors. (7 M-motors, 2 XL-motors, 1 battery box, 4 receivers, 4 extension wires, 1 light, 1 switch, 1 remote controller)

Pneumatic system controls: Cargo doors, Parking brake. (2 air tanks, 1 pressure gauge, 4 switches/valves, 1 pump, 1 small pump, 2 small cylinder, 2 medium cylinder, 7 T pieces, hoses)

Mechanical/Manual controls: Aileron, Elevator, Rudder, Control column, Pedals, Passenger doors, Emergency exits.

Electrical power: The electrical system is supplied by a battery box with 6 AA batteries. The 4 receivers and the switch are connected directly to the battery box. The lights are connected to the switch and they are placed on the wing’s leading edge inboard of the engines. The receivers get commands from the remote controller and each receiver has 2 channels. The first receiver controls the flaps + slats on one channel with 2 M-motors (these could be replaced with just 1 L-/XL-motor) and the landing gear on another channel with 2 XL-motors. The second receiver controls the thrust reverser with 1 M-motor and the spoilers also with 1 M-motor. The third receiver controls the trimmable horizontal stabilizer with 1 M-motor and the rudder trim with also 1 M-motor. The last receiver only controls the electric pump for the pneumatic system with 1 M-motor. Additionally, the system also contains extension wires due to the size of the aircraft.

Flight controls: The main flight control surfaces are controlled from the cockpit of the aircraft with mechanical connections. The aileron is controlled by turning one of the 2 yokes, the elevator by pushing or pulling on one of the yokes/control columns and the rudder by moving one of the pedals. The cockpit is made for dual pilot operation, thus includes 2 control columns and 2 pairs of pedals. High lift devices are installed on the wings, on the leading edge the slats can be found and on the trailing edge the slotted flaps. The flaps and slats are mechanically linked, so the movement can be done by 1 electric motor, but for faster deployment and retraction I installed a second motor, so in total these are powered by 2 M-motors. Each of the high lift devices are moved by mechanical actuators. The drag devices include the spoilers, which are installed on top of the flaps. These are powered by 1 M-motor and moved by mechanical actuators. The aircraft has 2 trim systems, one for the rudder and another for the trimmable horizontal stabilizer (THS). Each of the trim systems are powered by 1 M-motor and moved by mechanical actuator. The rudder trim includes an anti-servo tab actuated by mechanical actuator through linkages. The THS means the entire stabilizer is moving when the trim is adjusted, but the system is made in a way that it moves separately from the elevator.

Landing gear: The aircraft has 2 main landing gears and 1 nose landing gear, all of them with gear doors. The retraction and extension of the landing gears is powered by 2 XL-motors through worm gears. The retraction mechanism is a dual-sidestay system, which incorporates sidestay links and lock links. The main landing gear struts contain 2 shock absorbers with hard springs on each side. There are 2 wheels per main landing gear struts and the pneumatic powered drum brake assembly is installed within each of the wheels. The braking effect is achieved by flexible rubber connectors pushing against the wheel walls. The main landing gear doors are mechanically connected to the extension/retraction mechanism with a certain gear ratio and linkages to allow opening and closure. The doors are closed when the main landing gears are fully extended or fully retracted. The nose landing gear strut has 2 shock absorbers with soft springs and the structure is made in a way that the nose landing gear is free-castering with 2 wheels. The nose landing gear doors are mechanically connected to the nose landing gear main strut, so when the gear is extended the doors are open and when is retracted they are closed.

Lights: The aircraft has 2 landing lights, 1 installed on each side of the wings. The lights are controlled by a switch and powered by the battery box. The lights are installed in the leading edge of the wings inboard of the engines.

Pneumatic: The pneumatic system can be pressurized by a manual pump and an electrical pump, which is powered by an M-motor. The air is stored in 2 air tanks. The pressure in the system is indicated on the pressure gauge, the maximum pressure the system can achieve is around 2.4 bars. The cargo doors are moved by the medium cylinders with separate switches/valves. The parking brake is engaged/disengaged by 2 small cylinders and these are controlled by a common switch/valve. Additionally, a pressure relief valve is installed, with which the pressure can be released from the system.

Cargo: The aircraft has 2 cargo doors, 1 on the right side of the forward fuselage and 1 on the right side of the aft fuselage. Both cargo doors are moved by pneumatic cylinders and are controlled by separate switches to open and close. The forward cargo door provides access to the battery box.

Doors: The aircraft has 4 main doors and 4 overwing exits. The main doors open with hinges sideways and the overwing exits open upwards. The main doors remain in position by the friction of the parts, but the overwing exits include a simple lock mechanism for fixing them in closed position.

Fuselage: The fuselage structure is closest to a semi-monocoque design but without the skin. The structure is made up of formers and stringers.

Stabilizers: The aircraft has a vertical stabilizer and horizontal stabilizer in the tail section. The vertical stabilizer holds the rudder and the rudder trim system, while the horizontal stabilizer is trimmable and holds the elevator.

Wings: The cantilever low wing has sweep and slight dihedral. The wing structure is made of a main spar spanning from the root until the tip, 2 secondary spars and a false spar. The leading edge devices (slats) and the engines are installed on the main spar, but the trailing edge devices (slotted flaps, spoilers) are located at the secondary and false spars. Winglets are installed on the tip of the wing. The landing gear is installed between the 2 secondary spars.