PZL Mielec M-18 Dromader. English version

Cracow July 27, 2018

247c Section August 27, 1976

PZL M-18 Dromader

PZL WSK Mielec

Poland

 

The agricultural and firefighting aircraft.

Construction

PZL M-18 Dromader is a modern agricultural and firefighting plane, with a classic layout and in a characteristic yellow-white-black painting. This contrasting painting is supposed to increase the safety of people working at its service or in its vicinity. The crew cabin, which protruded above the fuselage, created a characteristic hump, which made the plane rightly named the one-humped camel - Dromader.

The aircraft has a large useful capacity, economy of use (low fuel consumption in relation to the useful capacity), the ability to work in agriculture and firefighting (forest fires), a large range, the ability to take off and land at airports with paved grassy or ground runways.

Construction

An airplane built in a classic system, a single-engine low-wing, with a fixed chassis. The plane's resurs (at the end of the 80's) was 6,000 hours, which was a great result. Permissible overloading of the structure; +3.5 g, -1.4 g. Metal construction.

Wings

The wing has a NACA 4416 profile at the fuselage and NACA 4412 at the end of the wing. The wings consist of three parts; the middle part and two attached wings. The center wing construction is one-girder. In addition, it is a rear power wall, therefore sometimes you can find the term - construction with auxiliary girder or double-girder. The center wing cover was made of duralumin sheet with a thickness of 0.5 mm to 1.5 mm. Two flaps are attached to the center wing, which are attached with three hinges. The outer parts of the wings were made in the same technology as the center wing. They are mounted under a small heel to remove the ends of the lobe from the ground. A pair of flaps and ailerons were mounted on the outside of the wings. Between the main girder and auxiliary girder, in the outer parts of the airfoil, 2 x 200 liter fuel tanks were placed.

All flaps and shuttlecocks are made of metal (aluminum alloys). The girder-ribbed construction, covered with sheet metal. Suspension of ailerons with ball bearings.

Fuselage

The fuselage of the aircraft is a truss, which is made of chrome-molybdate steel pipes connected by means of electric welding in an argon shield. The external truss is protected with epoxy enamels. The internal corrosion protection was made with oil. The cover was made of duralumin sheets. At the front of the truss, a barrier made of fire-resistant sheet metal is permanently mounted (heat-resistant steel). The engine bed is attached to it.

The laminated tank is mounted in the front part of the truss, using six fittings. The lattice has another eight fittings fixing the center wing in the lower part. The cabin skeleton is an integral part of the truss. It has been tested for possible capotage. The cabin houses the remote control and the trunk. The M-18 A and the next version have two tandem seats. The second seat is occupied by a mechanic or a pilot if it is a school version (dwuster). Glazing of the cabin with organic glass. A three-eye windshield. The front pillars were provided with a guillotine for possible breakage of an electrical or telephone overhead line. The cabin is equipped with an entrance door, both on the right and left side. The door opens outwards, downwards. In the event of an emergency, there is the possibility of an emergency door drop. The rear part of the truss has fittings for fixing the tail chassis and tail. The hull cover is fastened to the grate mainly by means of fast fasteners, screw-in locks and a small number of screws and bolts. Connections between individual sheets are sealed with gaskets and other sealing compounds.

Tail-plane

Classic tail-plane divided into rudders and ballasts. Completely metal. Steels balanced massively and aerodynamically. Suspended on ball bearings. The horizontal rudder was equipped with two balancing flaps. Electrically moved from the pilot's cabin. The construction of all units is girder-ribbed. Smooth or ribbed cover. At the top of the vertical tail, there is a fitting for the cable connecting with the roof of the cabin. It is protection against power and telephone wires.

Powered

The WSK PZL-Klaisz ASz-62 IR engine with 1 x 736 kW power. The engine is a 9-cylinder, air-cooled star. The engine is 4-stroke. The ASz-62 IRm18 version has a starting power of 1 x 721 kW (1 x 980 hp) at 2,200 rpm and a nominal power of 1 x 592 kW (1 x 804 hp) at 2,100 rpm. The engine is equipped with a centrifugal compressor, which ensures high power maintenance up to a certain level. The engine also has a planetary gear reducer. It allows you to reduce the rotational speed of the motor shaft, and thus the use of a larger and more efficient propeller. The motor is attached to the bed via rubber shock absorbers.

The propeller CN-PSL PZL-Warsaw AW-2-30 with a diameter of 3.30 m, constant speed. Blades with variable pitch. The change takes place by means of a hydraulic system. The pitch can be changed automatically using the constant speed controller or by using the lever from the pilot's cabin. The blades are equipped with counterweights balancing the moment of centrifugal forces.

Systems and installations

The control system consists mainly of rigid rods and arens (lines in the double-action armor, as well as gears in the bicycle). Flap valves hydraulically operated.

Hydraulic installation with a working pressure of 10-15 MPa. Swing the damper, brakes the wheels and the windmill of chemical pumps.

Electrical installation with a voltage of 24 V. The power source is a 50A / 24V alternator and a 24V / 24 Ah battery.

The plane has basic pilot instruments; artificial horizon, polygonal, VOR indicator, VHF radio station RS-6102. It is possible to install other devices depending on the wishes of the customer.

Specialist equipment.

Chemical tank.

The chemical tank is intended for loose substances (powder, granules) or liquids. The tank has a capacity of 2 500 liters and has a lifting capacity of 1 500 kg. The tank weighs approximately 120 kg. The shape resembles a pyramid with a top down. It has a coat made of glass laminate. The tank is reinforced with two steel strips. The tank is connected to the truss with six fittings. The charging opening was placed in the upper part in the form of a manhole opening outwards. When the hatch is closed, the latch locks hold it. The hatch is large enough for an employee to enter the facility to make repairs. There are two compartments in the interior that impede the free pouring of liquids. Three level scales are placed on the tank, which are visible from the outside and from the cockpit. Bottom of the tank is a basket for pouring, made mainly of stainless steel. A mixer is placed in the basket, which mixes and distributes the chemicals. In its side walls there are flaps which are adjustable and in this way the number of dosing agents is adjusted.

Installation for dusting.

Spraying of loose substances is carried out by apparatus that is easy to assemble and disassemble. It is placed under the pouring basket. Chemicals through the flaps in the basket get to the spreader. The spreader is built from channels beginning with a confusor and ends with a diffuser. In addition, it is possible to quickly empty the tank.

Apparatus for standard spraying.

At the beginning it should be noted that the plane can have two different spraying installations; standard and for fine spraying (for fogging). Standard spraying consists of a piping system, a pump system and typical sprinklers. The pump is driven by a windmill, about which I am writing below. The number of sprinklers, in the first version was 54 pieces, and in the second version as many as 100 pieces. The nozzle diameter ranges from 1.4 mm to 4.38 mm. The maximum expenditure is 0.17 liters / s at a pressure of 7 kg / cm2. The minimum expenditure is 0.03 liters / s at a pressure of 5 kg / cm2.

Apparatus for spraying with fine drops.

The fine particle spraying is used to spray liquid chemicals with very small droplet diameters using an atomizer. This installation has 8 atomizers. The chemical is supplied to one of the filters placed in front of the atomizer. Atomizer is a gushing unit whose basic element is a cylindrical net that rotates around the spindle. Each atomizer is driven individually from the air stream by a windmill with five plastic blades. The pitch of the blades is adjustable, thanks to which the rotational speed is controlled, which determines the size of the droplets of the liquid being sprayed. After passing through the mesh, the liquid gets to the diffuser and leaves the camera with high kinetic energy. The efficiency of the installation depends on the rotational speed of the windmill and the control valve (ball) controlled from the cockpit. The system has been equipped with hydraulic braking of atomizers, which makes it possible to stop the work almost immediately and just as quickly launch it. In addition, the system includes a pump, valve system, indicator system and a hydraulic shock absorption unit.

Installation for extinguishing fires.

The basic change in the chemical tanks is the replacement of the dumping bin, placed in the bottom of the tank, on the discharge flap. There are baffles in the tank making it difficult for the liquid to overflow. Of course, there is no remaining part of the spraying installation. The damper is fixed on the front side by hinges, and on the other three by means of locks.

The extinguishing agents are filled into the tank through the central refueling nozzle placed on the left side of the hull. The tank is automatically vented through the valve located in the charging flap. This eliminates the problem of pressure increase in the tank. The damper is activated by a lever located on the left side of the pilot's seat.

The M-18 plane takes 1 700 liters of water and 60 liters of detector (wetting or foaming agent), which increases the effectiveness of forest extinguishing. The bottom flap of the tank is 30 cm x 45 cm and it is pneumatically operated. Dropping a water bomb from the Dromader height of 30 m takes about 2 seconds. The surface coverage is about 60 m in length and 25-30 m in width. It is 1 800 m2.

 

General characteristics PZL M-18 Dromader (Data T-T)

Wingspan: 17.70 m (58,70 ft)

Length: 9.47 m (31,00 ft)

Height: 3.70 m (12,14 ft) to tail fin on ground

Wing area: 40 m2 (430 sq ft)

Empty weight: 2,710 kg (5,975 lb)

Max takeoff weight: 5,300 kg (9,259 lb)

Fuel capacity: 285 kg (900 lb) max fuel weight

Capacity tank: 2,500 litr (660 US gal; 550 imp gal) liquid or 2,200 kg (4,900 lb) dry chemical in fiberglass hopper forward of the cockpit (smaller hopper in M-18 BS)

Maximum speed empty: 256 km/h (159,07 mph, 138,23 kn)

Maximum speed with agricultural equipment: 200 km/h (124 mph, 108 kn)

Minimum speed: 109 km/h (67 mph; 58 kn)

Never exceed speed: 280 km/h (174 mph; 151 kn)

Range: 520 km (323,11 mi, 280,78 nmi)

Ferry range: 2,000 km (1,243 mi, 1,080 nmi)

Service ceiling: 6,500 m (21,300 ft)

g limits: +3.4 / -1.4

Rate of climb: 6.5 m/s (1,280 ft/min)

Wing loading: 105 kg/m2 (22 lb/sq ft)

Powerplant: 1 × PZL Kalisz ASz-621R 9-cylinder air-cooled radial piston engine, 731 kW (980 hp)

Propellers: 4-bladed PZL-Okęcie Warszawa AW-2-30, 3.3 m (10 ft 10 in) diameter constant speed aluminium alloy propeller

Crew: 1 person

Crew M-18 BS: 2 persons

 

Written by Karol Placha Hetman