Engines

GAS418S

High specific power UAV engine for middle to high altitude applications

KEY FEATURES

Two engine versions are available to meet the widest range of installation requirements. Both horizontal and vertical axis installation are possible.

The GAS418S has a very compact size. It is thus to fit it into very small fuselages, helping to keep the overall weight low. Specific power is very high, going up to 2.31 hp/kg in the horizontal version. Peak power at sea level is 180hp @5800RPM.

The GAS418S relies on a single stage centrifugal supercharger, which is driven mechanically to increase its performance at high altitude.

Medium-high altitude performance of the mechanical supercharger are better than the turbocharger ones. The lower air density modifies the expansion ratio of the turbine, limiting the overall boosting capability due to anticipated turbine over speed.

Fuel injection and ignition are completely electronic and ECU controlled, making the engine run at its best under a wide range of ambient conditions.

All parts used inside the engine are manufactured in Italy or in countries of the European Union. The engine is completely designed and assembled in house at Flygas, based in the Italian motor valley.

GAS418S engine runs with the standard 98 octane number automotive gasoline.

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Diagrams

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GAS418S Brochure (PDF downloadable)

Flygas-912-Rotax

Flygas-912-Rotax E.F.I. SUPERCHARGED

On the market, there are not pistons engines intended for Ultralight Experimentals Aircrafts that use Centrifugal Superchargers and double (redundant) Fuel Supply Plant.

Flygas offers that kind of engine, made up from a GREAT Rotax 912 ULS standard engine equipped with Flygas innovative technical solutions.

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Flygas is the first & only firm on the market doing this!

Today all electronic fuel injection engines use a fuel pressure of 3 bar (10 times higher than 0.3 bar-4.5 PSI respect carburetor engines).
In the event of an emergency landing, with possible impact on the ground and trees, all E.F.I. engines still maintain the fuel supply line which is close to the engine at a pressure of 3 bar (45PSI), despite the pump of the fuel is turned off. This significantly increases the risk of fire, even in the event of a limited impact!

Since 2007 Flygas has been the only company in the world to create a redundant fuel supply system (injection and carburetors)
that allows you to quickly switch from injection to carburetors, discharging the high pressure of 3 bar (necessary for injection) down to 0.3 bar (required by carburetors)! Therefore, even in the event of a minor impact, the fuel spill following a break will be 10 times less than any other fuel injection system on the market today.

Flygas is the only firm in the world today that produces a Mechanical Fuel Pump for Rotax 912 Turbo or Supercharged engine.

Mechanical fuel pump and carburetors will allow your engine to work 100%, even in case of a 12 Volt power failure!

We supply the engine (Rotax 912 ULS New) completely assembled, bench tested and equipped with the following Flygas kits:

• SUPERCHARGER Rotax 912 – 142HP
• Redundant Electronic Fuel Injection “Fly-Safe”
• Mechanical Fuel Pump 3Bar
• Intake Manifold Kit with big compensating pipe

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Main specifications

• 4 cylinders, 4 strokes, 1.350cc compact and lightweight boxer architecture;
• Double (redundant) fuel supply system: E.F.I. and Carburetors;
• Centrifugal SUPERCHARGER, mechanical drive, boosting power up to 142Hp;
• Mechanical Fuel Pump 3Bar;
• Runs with normal gasoline 95Ron.

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Comparison table

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Advantages

• Best performance, even at high altitudes;
• Better fault-tolerance, for greater safety;
• More power with less weight, increased load capacity;
• Mechanical 3 Bar Fuel Pump ensuring fuel flow independently from 12v supply

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Technical insights: fuel supply system

STATE-OF-THE-ART: Electronic Fuel Injection systems (E.F.I.)

1. They are expensive;
2. They always maintain a 3 bar fuel pressure close to the engine, increasing the risk of fire in case of a ground impact or if a pipe breaks;
3. Redundant E.F.I. (with dual sensors, dual injectors, etc.) are heavy and complex;
4. The Electronic Fuel Injection system (even if redundant) requires the continuous availability of a 12v supply voltage to operate.

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FLYGAS SOLUTION:
“Fly-Safe” REDUNDANT Electronic Fuel Injection system

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SINCE 2007, YOU CAN HAVE A DOUBLE FUEL INJECTION SYSTEM ON BOARD (E.F.I. AND CARBURETORS)

The “Fly-Safe” Electronic Fuel Injection system by Flygas stands as a parallel unit to the Carburetors.

At any time, the pilot can rapidly change from E.F.I. back to Carburetors and vice versa simply pushing or pulling the Flygas “K.E.D.” (Knob Exchange Device) on the cockpit.

In case of any malfunction with the E.F.I. the pilot can quickly change back to Carburetors, restoring engine operation and restarting it in two second!

This is also particularly useful in any unlikely case of emergency landing.

In order to reduce the risk of fire due to a heavy ground impact, you can discharge the high-level fuel pressure (3 bar -45 psi) of the E.F.I. to the low-level fuel pressure (0.3 bar – 4.5 psi) of Carburetors.

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“Fly-Safe” (with “big compensation pipe”) ADVANTAGES:

1. No ice forming in the intake manifold.
2. Lower fuel consumption.
3. The stoichiometric ratio will always be the best for the current atmospheric condition.
4. The stoichiometric ratio will be automatically adjusted, according to altitude.
5. Absence of vibration, regardless to the difference in the opening of carburetors.
6. Possibility to continue flying (at 50% of power) even if the wire command of a carburetor breaks. You could even fly with a carburetor completely disconnected from the collector (e.g. in case of breakage of the rubber fitting).
7. Independent and optimized carburation for each cylinder (currently, especially in supercharged engines, carburetion is optimized only for the thinnest cylinder.).
8. Prevention of detonation that can always happen in a supercharged engine whenever the stoichiometric ratio turns low.
9. Optional “dialogue” dashboard displaying the engine data that can also record them. For further diagnosis, the pilot or the maintenance engineer can remotely send the latest flight data (e.g. before a long journey) to Flygas for evaluation and control – OPTIONAL REMOTE CONTROL SERVICE.
10. Integration of all the electrical switches (electric pumps, 12-volt control unit, and starter motor) into a single command (the K.E.D.) so that you can activate them simultaneously and quickly.

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Technical insights: Supercharger

STATE-OF-THE-ART: Turbochargers

Turbochargers are very often used to boost power of combustion engines, but they have some limits:

• Very high backpressure in manifold exhaust: this implies a very high exhaust temperature, increasing the risk of knocking combustion.
• Turbine over-speed: when the altitude increases and the ambient pressure becomes low, the turbo shaft starts spinning very fast, quickly bringing the turbine to an over-speed state. In this case, the expansion ratio of the turbine can become too high for the engine to bear.
• Very heavy, as they have to be made of cast iron.

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FLYGAS SOLUTION:
Centrifugal Supercharger with mechanical drive

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More Power with less additional weight – increased load capacity

Comparison table

Gas-Supercharger ADVANTAGES:

1. Exhaust Temperature very low compared to turbo engines.
2. No high backpressure in manifold exhaust.
3. No electronics “TCU” to control boost.
4. Supercharger’s oil plant completely separated from engine’s oil plant (optional).
5. Low weight installed.
6. Increased rotational inertial mass, which allows the engine to run smooth, as if it had a large flywheel.
7. Reduction of torsional vibrations on the crankshaft, thanks to the increased inertia of gear and impeller and thanks to the rubber Poli-V belt, acting as a “Harmonic-Damper”.
8. No risk of turbine over-speed, because the compressor-shaft is driven directly by the engine, with a pulley and belt system, and not by exhaust gas flow.

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Technical insights: mechanical fuel pump

STATE-OF-THE-ART: Electrical fuel pump

All E.F.I. engines use an electrical pump to supply fuel flow, but this comes with some issue:

1. The flow of fuel depends on the availability of the 12-volt power supply. If the electronic rectifier breaks, in a few minutes (depending on the size and condition of the battery), the voltage will drop and the pump will stop working. To avoid this, you could install a secondary alternator, but this is heavy and expensive.
2. Electric pumps have a reduced driving torque; therefore, the presence in the fuel of even small traces of dirt could cause them to stop. To avoid this, all electric pumps are equipped with a very small, fine-meshed inlet filter with a tiny surface area.
3. Each electric pump requires almost 6 Amp/h from the electrical power supply.

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FLYGAS SOLUTION:
Mechanical fuel pump (primary) + Electrical (secondary)

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Increased reliability and safety, while saving electrical power

Flygas Mechanical Fuel Pump is driven directly from the crank-shaft and is installed on the engine flywheel, in a protected position in the event of an emergency landing.

It ensures a constant fuel flow at 3 bar pressure, while having a very light weight (only 680 grams: just basically the same weight as an electrical Pierburg fuel pump, complete with wires and switches.)

It replaces one of the two electric fuel pumps normally installed on a Rotax 912 and is configured as the “primary” fuel pump, leaving the residual electric pump as ”secondary”.

Remember: all aircraft and racing engines have always been equipped with mechanical fuel pumps, and they still are today!

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Mechanical fuel pump ADVANTAGES:

1. Fuel flow no longer dependent on the 12-volt power supply.
2. More reliability. The torque of our mechanical fuel pump is very high, so it will never stop even if there are traces of dirt in the fuel. In the case of highly polluted and dirty fuel (obviously to be avoided) the mechanical pump could still start to deteriorate, reducing its flow rate and maximum pressure, but without stopping. You must however keep in mind that our pump can carry more than 160 liters per hour and has been designed to supply up to 14 bar of pressure, while a Pierburg electric pump can carry only 100 lt / h. Therefore, our mechanical pump has a wider safety margin even in case of deterioration over time.
3. Electrical power saving, which can thus be used for other services.
4. Greater cleanliness of the fuel plant, with fewer switches and wires and fewer pipes passing through hot areas near the engine (risk of “vapour-lock”).
5. Increased fire safety. If the engine stops, the fuel flow also stops. The pump is located in a protected area in the event of a crash: behind the flywheel.

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Download our BROCHURE: