L-39 Specifications
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L-39 Diagram

General Description

The L-39 advanced trainer is in daily use by the air force's of sixteen countries in Europe, Asia, Africa, and Latin America.  It's rugged and simple design has proved its qualities in every climate from desert summers to Siberian winters to tropical jungles. The aircraft's well designed systems result in easy maintenance, excellent reliability, simple pre-flight checks, and no requirement for a full-time ground crew. A turbofan engine with low fuel consumption and low sensitivity to foreign object damage (FOD) is combined with high wing protected air intakes. This makes the aircraft ideal for operations from unimproved airstrips and for training. The excellent handling qualities make it one of the best training aircraft in the world.

L-39C Training version.
L-39V  Single seat version for Target Towing
L-39ZO Improved version for training with reinforced wing
L-39ZA  Ground attack and reconnaissance version with gun pod and four 
hardpoints under the wing.
L-39ZA/MP  Multipurpose version with western avionics and HUD

Power Plant
The aircraft is powered by a AI-25 TL twin shaft turbofan engine. The control of the engine is hydro-mechanical with an emergency backup circuit. The engine is attached to the airframe by means of four hinges enabling quick removal of the engine after rear part of the fuselage is disconnected.

The engine is automatically started on the ground by means of air starter, that is fed by compressed air from the Saphir-5 auxiliary power unit (APU). In the air, to the engine can be restarted by either the APU or autorotation.

The bypass ratio of the engine is 2.0. Maximum static thrust is 16.87 kN, specific fuel consumption 56.9 kg/kN.hr.

Elevator, ailerons, and rudder are controlled through the direct mechanical system. Flaps and airbrakes are actuated by electro-hydraulic system. In case of failure, the functions can be performed by an emergency hydraulic system.

Landing Gear
The aircraft has a rugged tricycle undercarriage that is designed to work as well on unpaved runways  as it does on concrete or grass. The main undercarriage wheels are equipped with hydraulically operated double-disk brakes with an antiskid system. The forward retracting nose wheel has a shimmy damper.

Aircraft Systems

Hydraulic System
The main circuit of the hydraulic system provides the power needed to operate the flaps, airbrakes, landing gear, ram-air-turbine, wheel brakes and braking anti-skid devices. Power is supplied by a variable delivery constant pressure pump working at 15Mpa (2000psi). The emergency circuit is supplied by an hydraulic accumulator.

Pneumatic System
Pneumatic canopy seals are supplied by a 2 liter compressed air bottle in the nose compartment.

Electrical System
The main electrical system runs on  28V (DC). The auxiliary electrical system is a  three phase system  (3x115/200V - 400Hz.) In addition to the main system, the aircraft is  equipped with both reserve and emergency systems.

Fuel System
The aircraft's fuel is contained in five tanks in the fuselage, two fixed wing-tip tanks, and two optional under wing drop tanks. Total fuel capacity is 1,995 liters.

Air-conditioning and Oxygen System
The pressurized cockpit is equipped with automatic pressure and temperature regulation. Oxygen masks in both cockpits can be used for long duration high altitude flights.

Anti-G System
An anti-G system protects the pilot from the effect of high load factors during maneuvers by using special suit with automatic regulation.

De-Icing System
The aircraft de-icing system protects the windshield and both air intakes and runs on hot air from the engine compressor.

Ejection System
The ejection system ensures reliable egress of the pilots in the whole range of operating speeds from 150 km/hr up to maximum permissible airspeed from zero height up to maximum ceiling. Two VS1-BR1 ejection seats with autonomous survival kits are installed.

Testimony to the reliability of the L39 is proven in the number of L39 aircraft being currently used and in the repeat orders from existing customers. The Mean Time Between Failure in flight is higher than 300 flight hours. The probability that a one hour sortie will be successfully completed is 99.6%. The safety record of the L39, combined with its unique built in features make the aircraft highly cost-effective for its mission.

Rapid Servicing and low maintenance cost was one of the main criteria in the development of the L39. For easy servicing and maintenance, the airframe is furnished with large numbers of access doors with quick release locks, and easily accessible from the ground with simple airfield servicing equipment. The engine can be removed and fitted back in less than three hours. All parts of the airframe are replaceable and interchangeable. Overhaul of the airframe is required after 2,000 hrs and overhaul of the engine after 1,000 hrs. Proven airframe service life is 6,000 hrs. 


Weights and Loading Lb Kg
Equipped Empty Weight* 7,584 - 7,892 3,440 - 3,580
Ramp clean weight 10,097-10,406  4,580 - 4,720
Max internal weight 12,500 5,670 
Max internal and external fuel using 2x350L underwing tanks 3,360 1,524
*Empty weight depends on avionics installed    
Fuel Load Lb Kg
Fuselage Tanks 1817 824
2x 100L wingtip tanks 344 156
2x 150L underwing tanks 516 234
2x 350L underwing tanks 1221 554
Performance US  Czech  
Basic performance data (for a/c weight 4,300 kg)    
Maximum level speed 407 Kts 755 Kmh
Dive Speed 491 Kts 910 Kmh
Stall Speed (Clean) 103 Kts 190 Kmh
Stall Speed (Full Flaps) 91 Kts 169 Kmh
Maximum climb rate 4,330 Ft/Min 22 Metres/Second
Time to climb to 16,400ft/5,000M 6 minutes 6 minutes
Range (with underwing tanks):  971 Nautical Miles 1800/Km
Endurance  4 Hours 4 Hours
Takeoff distance over 50 ft (15M) obstacle 2,625 feet 800 Metres
Landing Distance over 50ft (15M) obstacle. 3,050 feet 930 Metres
Service Ceiling 36,080 feet 11,000 Metres
Dimensions Feet Metres
Wing Span 31 9.46M
Length 39'10" 12.13M
Height 15'5" 4.77M
Wing Area 202 Sq Feet 18.8 Sq Metres