YouTube – Aero L-39
pilot + student
39 ft. 10 in.
The design for the Aero L-39, called Albatros, originated in Czechoslovakia in 1966. It remains among the most popular advanced jet training aircraft in the world today. Pilots from some thirty nations around the world have received their training in the aircraft.
The popularity of the aircraft is due to numerous attributes. It uses an extremely reliable and efficient turbofan engine that is simple to maintain. Pilots report excellent visibility all around the aircraft. Docile handling characteristics plus high performance make the Aero L-39 an excellent advanced trainer. An added benefit is the ability to operated from smooth grass and unimproved landing fields.
In addition to pilot training, the Aero L-39 is used for ordnance training and light troop support.
Flying the Aero L-39:
Starting the aircraft consists of going through your checklist to ensure that all switches and indicators are where they should be. Find the button marked “turbo” and depress it. In less than half a minute a light should illuminate indicating that the APU is ready for engine start. Depress the “engine start” button, and move the throttle to the “idle” position. When the light goes out you can let go of the button. Go to your checklist to see what switches need to be activated now that the engine is running. Be sure that the exhaust gas temperature is in its proper range and the bleed valve is operating normally.
To turn the aircraft while on the ground, differential braking is applied through a combination of using the rudder pedals and applying the brakes by squeezing their handle on the control stick. The steering is not self centering, and this takes some getting used to. To slow or stop the aircraft, push the pedals and squeeze the control stick brake handle simultaneously.
Once the Aero L-39 is centered on the runway, the brake handle is squeezed and RPM brought up to 106 percent. With all gauges and lights checked and within proper operating range, the brake is released.
During the takeoff roll, the same methods are used to keep the aircraft centered down the runway. The more corrections necessary to keep the aircraft going straight, the longer the takeoff run.
The engine spools up slowly, and you feel a gentle pressure back in your seat, rather than a shove. The rudder becomes effective at around 45 mph, at which time it becomes easy to keep the aircraft rolling down the center line of the runway. Rotation is at about 105 mph by pulling the control stick towards you around two inches. The nose wheel will come up from the runway at about 115 mph. At about 125 mph the Aero L-39 will lift off with about eight degrees of nose up. When a speed of 160 mph is reached, the flaps can retract. You want to keep the nose from getting too high to increase your air speed as quickly as possible to 190 mph. That is the initial turn speed necessary in the event the engine quits. Make sure all gauges show normal engine operation and be sure that the cockpit pressure gauge shows pressure building inside.
A climb rate of 2,000 fpm can be established at a speed of 240 mph. At around 8,000 feet of altitude the climb rate slows. By the time 16,000 feet is reached, it will be down to about 1,000 fpm.
At a VFR flight level of about 17,000 feet a throttle setting of 98 percent will result in a speed of about 340 mph with a fuel consumption of about 150 gallons an hour. The best cruise altitude of the Aero L-39 is at about 24,000 feet, where at the same throttle setting it will cruise at around 365 mph with fuel consumption around 135 gallons an hour. With internal fuel the aircraft has a range of around 575 miles. Add wing tip drop tanks and the range increases to over 900 miles.
Many Aero L-39 aircraft are used for aerobatics, both individually, and in air teams. They are capable of up to +8G and up to -4G maneuvers. When first attempting aerobatic maneuvers the pilot should be aware that it takes minimal effort to achieve the maximum G forces. The size and weight of the aircraft and its speed combine to hold a maximum G maneuver. Traveling at the speeds of the Aero L-39 covers a lot of air space in little time. It is necessary to allow sufficient room to perform maneuvers. That means keeping the start of your loops and vertical maneuvers high enough to allow for plenty of recovery time.
The Aero L-39 is an ideal training aircraft. It is easy to fly, hard to over control, and has a large flight envelope. Those same qualities make it ideal for aerobatics. Loops are typically accomplished at full throttle with an entry speed of 370 mph, pulling up at about a 45 degree angle. By raising the nose about ten degrees and pushing the stick hard to one side, one can complete aileron rolls while flying level, at a 270 degrees a second rate.
To spin the aircraft, speed should be around 125 mph. The aircraft holds left spins more uniformly than right spins, which can be entered more quickly. Recovery is straight forward and can be accomplished with less than an additional revolution when countering the spin.
The aircraft does not stall easily, and will give you plenty of warning when approaching a stall condition. It is possible to keep the nose pointed above the horizon,, while the Aero L-39 is fully stalled, by using the rudder to level the wings. However, you will be losing altitude at up to 4,000 fpm. Recovery is just a matter of lowering the nose and adding power until sufficient speed is achieved for controlled flight.
When entering the landing pattern, ideally you will be flying at an altitude of 1,500 feet at a speed of about 285 mph. Turn bank can be at 60 degrees to lose speed and altitude quickly. Deploy the speed brakes and put the throttle to idle. At below 205 mph the gear can be lowered. Level the aircraft, and bring the power up to above 70 percent. That will minimize the time it will take to achieve full engine thrust in the even of a go around. At 185 mph set flaps to 25 degrees. Power is increased to around 85 percent to keep above 1,000 feet while on downwind approach. When the aircraft slows to 160 mph, full flaps can be deployed. Keep the speed up to at least 155 mph until you are on final approach. This should put you at about 250 feet of altitude and a quarter mile from the end of the runway. Bring the throttle back to 140 mph and then raise the nose about seven degrees as you gently touch down. Keeping the nose up will help to slow the aircraft while saving brakes and tires.
The Aero L-39 maintenance is among the simplest of any jet aircraft available in civil aviation. The pressurized air conditioned cockpit just make it that much more special. The price of the L-39 is lower than just about any comparable aircraft, there are parts readily available, and it gives more joy to fly per dollar than any other aircraft.
A total of some 2,900 Aero L-39 aircraft were produced from 1971 to 1996 when production ceased.
RC Aero L-39