The fact that PBS products are considered high quality around the world is proven by feedback from our customers, both producers of aviation technology and end-users, but also by the number of devices and equipment that we’ve manufactured. The number of environmental control systems for aircraft and helicopters alone that we’ve supplied since 1972 is over 5,000, which is an unbelievable number in the aviation industry. Aero Vodochody mostly contributed to this success.
Pic. 3: The pre-cooling system and the environmental control system devices for the L-39NG
Aero Vodochody’s production
AERO Vodochody AEROSPACE a.s. is the largest aircraft manufacturer in the Czech Republic and is one of the oldest manufacturers of aircraft in the world. It has a strong position mainly in the market of military training and light combat aircraft.
The L-39 Albatros, thanks to the hundreds of used aircraft, was and still is a versatile aeroplane intended for basic, continuing, and combat training, and it may be used as a light combat aircraft. It has gained worldwide popularity thanks mainly to its flight characteristics, easy control, and high reliability. From 1971 – 1997 there were almost 2,900 of these aircraft built.
From 1992-1996, 60 modified aircraft were built under the designation L-39MS, and also L-59 Super Albatros for export.
By the end of the nineties, Aero supplied 72 L-159 Alca fighters to fill an order for the Czech army. The Czech Army later decided that it will only operate half and spent a long time looking for a buyer for the rest. Later, Iraq bought 15 in 2015.
After a nearly 10-year long silence when Aero mainly worked on research and development and the manufacturing of components for aircraft and helicopters for the leading world aircraft manufacturers and also with general repairs and modernisations of previously manufactured aircraft, Aero is returning to the manufacture of subsonic aircraft. The successful L-39 model will be followed by the L-39NG (new generation) model. At the same time, Aero is renewing its production of the L-159 Alca aircraft, including the innovated versions designated F/A-259 Striker, and it’s also restarting the production of the re-motorised version of the L-39CW.
The L-39NG aircraft
Development of the L-39NG aircraft began in 2014. The take-off of the first prototype is planned for the end of 2018 and delivery to the first customer in 2019. The costs for development will be around CZK 250 – 300 million (Editor’s note: the amount was provided by Giuseppe Giodro, the CEO of Aero Vodochody, in one of the interviews for the Czech press).
This is a completely new aircraft which will combine a proven aerodynamic concept with the most modern technologies and systems which, according to the manufacturer, guarantees a long lifetime, a wide use, and high operational performance with low acquisition and operating costs.
The operating costs will be about EUR 1,500 / 1 flight hour. For comparison, the cost for one flight hour of the JAS 39 Gripen fighter jet which is used by the Czech army is about EUR 4,600.
The key change in the L-39NG aircraft is the installation of a modern twin-jet engine, the FJ44-4M from Williams International, the use of a wing with integrated fuel tanks, and the use of advanced systems in the cockpit area. According to surveys, a supply of approximately 180 aircraft is expected for 2020 – 2030.
At the same time, Aero is registering 22 orders for the L-39NG aircraft with an option for another 16.
Pic.2: L-39NG Demonstrator
History of cooperation between PBS and Aero Vodochody
Turbostarters - starting the AI-25 W jet engines in the L-39 Albatros training aircraft. In 1969, they were the first ever PBS products for an aviation programme. In the following years, they were replaced by the manufacturing of the Safir 5 air generator, which is the predecessor of today’s APU Safir 5K/G, which still belongs among the key products of the aircraft division, and for PBS from the point of view of sales. In 1972, we also supplied 11 out of the 4,500 sets of environmental control systems for the L-39.
Current cooperation between PBS and Aero Vodochody
By the end of 2014, we’d been approached by AERO Vodochody with a project for the re-motorisation of their existing L-39 aircraft under the designation L-39CW and with the project for the development of a completely new aircraft, the L-39NG.
The L-39CW programme involves the re-motorisation of the current L-39 aircraft with the twin-jet FJ44-4M engine and equipping the aircraft with modern avionics (the cockpit area is dominated by displays) so that the pilots may easily transition to modern super-sonic jet aircraft. The new drive unit has practically identical thrust to the old one but it has a dramatically lower consumption and more favourable operating characteristics. There are currently about 800 L-39 aircraft in the world at the moment, with about 160 ready for redevelopment.
The use of the new FJ44-4M engine has had a notable effect on the development and supply of equipment from PBS. The engine is started electrically, which is why the aircraft, in comparison with the existing L-39, doesn’t need an auxiliary power unit. It also has significantly higher parameters on the extraction of air for the environmental control system, the oxygen generation system, and the Anti-G (pressurised pilot suits) system.
As part of the development of the equipment for the L-39CW and the L-39NG, we have dealt with the following systems:
1. Devices for the pre-cooling of extracted air
Since using the new engine, the parameters for extracted air have increased to a pressure of 2.2 MPa and a temperature of 500°C. The high temperature posed a problem mainly because it was necessary to develop a system for the pre-cooling of the extracted air, which had to function both on the ground and also in flight, and it must cool down the air to a temperature of around 200°C. The solution was the use of two pre-coolers which cool by using the ejectors on the ground and in flight they rely on the ram effect. The necessary regulation system also had to be developed. The entire system is supplied and verified by both flight tests and on-ground tests on the demonstration aircraft. The system is used on both the L-39CW and the L-39NG aircraft.
2. Environmental control system
The devices of the environmental control system are derived from the modified existing devices from the serial production. The largest difference is the use of electronic regulation with the control electronics, which ensures not just the function of the entire system but also monitors the system and registers any malfunctions. The system is only used on the L-39NG aircraft and the existing system is left on the L-39CW aircraft.
3. Devices for the oxygen generating system and the "Anti-G” system
These are devices for the reduction and cooling of extracted air from the engine for the aircraft’s subsystems for the generation of oxygen and the pressurisation of the pilots’ Anti-G suits. The system is used on both the L-39CW and the L-39NG aircraft.
4. Fuel system Devices
For the fuel system of the aircraft, PBS developed a completely new device serving for the opening/closing of the aircraft’s fuel tanks during refuelling and repumping fuel between them in flight. This device is called the filling valve. Additionally, float sensors have been modified to measure the amount of fuel in the tanks. The system is only used on the L-39NG aircraft.
5. 6 kW EMG 200 power supply
At the time when Aero Vodochody was working on the re-motorisation of the aircraft, development was underway in PBS for a 6 kW power supply (the starter-generator and control unit) which would be suitable for the aircraft and that could be placed on the engine. The only complication was the opposite direction of turning the drive on the engine. Nonetheless, a modification was made to the starter-generator for a reversed turning direction. The EMG 200 is used on both the L-39CW and the L-39NG aircraft.
In total, 32 types of devices and equipment, 11 of which are used on the L-39CW (the set contains 13 pieces) and 32 are used on the L-39NG (the set contains 43 pieces), were either modified or newly developed.
The prototypes of the pre-cooling systems, oxygen generating systems, Anti-G systems, and the starter-generator were verified by ground and flight tests on the demonstrator L-39NG. The first complete set of devices for the L-39NG were supplied, the delivery of the second set of devices is planned in autumn 2018.
We believe that the almost 50-year long and very successful cooperation between PBS and Aero Vodochody will continue and that the new or innovated aircraft from Vodochody with components from PBS will continue to gain praise and demonstrate the high level of the Czech aviation industry around the world.