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Front and rear cockpit of Greenwald’s L-39. For a pilot with jet experience, an L-39 type rating can be accomplished with no more than a few hours of transition training. For those new to jets, plan on 10-15 hours depending on aptitude and prior experience.
brakes to be activated from the emer- gency circuit. Dual accumulators store additional hydraulic energy and serve as dampeners for pressure f luctuation during operation.
Electricity is supplied by a large gen- erator backed up by a ram air turbine generator (RAT) that automatically de- ploys from the aft lower fuselage in case of generator failure. In many aircraft, this heavy system is removed and electrical back-up is provided by a battery bank in the nose with up to 5,200 amp-hours of reserve. The battery bank helps main- tain weight and balance since the aircraft tends to be tail-heavy when armaments are removed. Maximum amperage for all systems never exceeds 50 amps in flight, so the large batteries provide more than enough emergency power.
One of the more interesting sys- tems is the Saphir 5 starter unit. This is a stand-alone jet engine that supplies air power to start the AI-25TL engine. The Ivchenko powerplant is a low bypass (1.7:1) turbofan that supplies 3,800 pounds of thrust. The engine is protected by an RT-12 EGT Limiter that interrupts fuel flow in an over-temperature situation. An override switch deactivates the RT-12 for emergency fuel delivery. Fuel is carried in the fuselage (290 gallons) with standard wing tip tanks holding an additional 54 gallons. The five interconnected fuselage fuel tanks require patience when fueling; the last 5-7 gallons are added slowly as the tanks will slowly “burp” trapped air when almost full. A 3-gallon dedicated “negative G” fuel reservoir allows no more than 20 seconds of inverted flight. Auxiliary fuel tanks can be fitted under the wings and in the fuselage. Fuel management is auto- matic, with bleed air pressure driving fuel
from the tip tanks to the main fuselage tank. An electric low-pressure pump takes over from there to feed the engine’s high- pressure injector. Bleed air is also used to pressurize the cockpits. This is done auto- matically to a max pressure differential of 3.5 PSI for a 12,500-foot cabin at 21,000 ft. Above this altitude supplemental oxygen is provided via an onboard system.
Most converted civilian aircraft have an empty weight of about 7,000 pounds. The Max Gross Weight of 11,485 (11,830 for –ZO) allows a full-fuel payload of more than 1,500 pounds – plenty for two pilots and their bags.
The performance is impressive: Mmo is 0.8 Mach with typical high-speed cruise speeds of 340 KTAS at FL180. The plane I fly does a bit better than that at 370 KTAS, probably due to its light weight. Fuel burn in the L-39 is also impressive, but like all turbine-powered aircraft, this rapidly decreases with altitude. On take-off, the engine rips through almost 400 gallons per hour (gph). High-speed cruise at FL180 draws about 180 gph. Closer to the service ceiling of 37,000 feet, TAS is 300 kts, and fuel burn drops to 120 gph.
Because it is a turbofan-powered air- craft, piloting the L-39 requires a type rating. For a pilot with jet experience, this can be accomplished with no more than a few hours of transition training. For those new to jets, plan on 10-15 hours depending on aptitude and prior experi- ence. Pilots must have 1,000 hours TT with 500 hours PIC. Ground school is a must. The Albatros is certified in the Experi- mental/Exhibition category so renting one for training is disallowed by the FAA unless the aircraft provider has a Letter of Deviation Authority (LODA).
Preflight
The preflight starts in front of the left wing. A look down the yawning air scoop allows inspection of the fan blades. On the left fuselage, an access panel is opened to check the nitrogen charge of the twin hy- draulic accumulators. Higher up, another access panel opens to check the hydraulic fluid reservoir (for an accurate reading the system must first be depressurized). After a look up the tailpipe, engine oil is checked through a clear window on the right fu- selage. Tires and brakes are checked, as are the wheel wells. A panel on the left nose cone provides access for two toggle switches that energize the fire detection/ suppression system and the ejection seat circuits. Pencil-like barber poles stick up through the nose and the wing roots to provide visual confirmation the gear is down and locked. Fully extended flaps have their own barber pole indicators.
The VS-1 BRI ejection seats are a contro- versial option: maintaining them can be costly, and some pilots are uncomfortable sitting on top of three explosive charges and a rocket motor designed to propel a pilot upward with a 16G acceleration. Ejec- tion seat training must be completed using an FAA-approved syllabus, and recurrent training is mandated every two years. Ejection from ground level is prohibited below 81 KTAS since at low speeds the canopy may not completely disconnect from the aircraft. There is an electronic lock-out mechanism that will prevent both pilots from simultaneously ejecting into each other. In the case of a frozen canopy, there is a through-the-canopy ejection option, and in the case of an un- controlled landing where the canopies become jammed there is an explosive canopy deployment module. Simplicity
12 • TWIN & TURBINE
February 2019