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Regional Gliding School The Carburetor ¶measure the correct quantity of fuel and vaporize this fuel, ·mix it with air in the proper proportion, and.

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Presentation on theme: "Regional Gliding School The Carburetor ¶measure the correct quantity of fuel and vaporize this fuel, ·mix it with air in the proper proportion, and."— Presentation transcript:

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3 Regional Gliding School The Carburetor ¶measure the correct quantity of fuel and vaporize this fuel, ·mix it with air in the proper proportion, and ¸deliver the mixture to the cylinders. The carburetor has three important functions:

4 Regional Gliding School Components of a Carburetor äVenturi Øair is drawn into the venturi and because of its shape, the air is accelerated while the pressure is reduced äNozzle Øprovides a passage for fuel from the float chamber to the venturi Øreduced pressure draws fuel into the venturi where it is vaporized

5 Regional Gliding School Components of a Carburetor äThrottle Valve Øregulates the volume of fuel/air mixture äIntake Manifold Ødistributes the fuel/air mixture from the carburetor to the cylinders äFloat Chamber Øcontains a consistent level of fuel in order to keep fuel supply steady Throttle Valve To Intake Manifold Float Chamber

6 Regional Gliding School Components of a Carburetor äNeedle Valve Øopens and closes the fuel line and is controlled by the float äVent Øallows the pressure to be equalized with that of the changing outside air pressure äIdle Jet Øused to keep the engine going when there is insufficient air flow to draw in fuel from the nozzle

7 Regional Gliding School Fuel/Air Mixture vThe ratio of fuel to air is regulated by the pilot with the mixture control. vThe throttle valve regulates the flow of air/fuel mixture into the engine. It also creates turbulence to assist in the mixing of fuel and air. vThe proportion of fuel to air is governed by weight and not by volume.

8 Regional Gliding School Fuel/Air Mixture vThe chemically correct mixture is about 1:15, where it is one part fuel to fifteen parts air. vAn engine will run hotter with a lean mixture because the lean mixture is slower burning, exposing the cylinder walls to high temperatures for a longer period of time. vAn engine will run cooler with a richer mixture because the rich mixture burns more quickly.

9 Regional Gliding School NOTE: You must use the buttons in the Confirmation Stage

10 Regional Gliding School Aero Engines Carburetor and Exhaust Systems A B C D Weight Mass Area Let's try a few review questions on Aero Engines: Question #1 - How is the mixture of gasoline to air measured? Volume

11 I’m afraid that answer is incorrect Let's try again... Flying Scholarship Program

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15 Regional Gliding School Mixture Control àAs altitude increases, the density of air decreases. àCarburetors are calibrated for sea level operation. àTherefore, with altitude, the mixture would become over-rich, causing a waste of fuel and a loss of power. àMixture control is fitted to adjust the amount of fuel being drawn from the nozzle. àMixture control can be used to produce a rich or lean fuel/air mixture.

16 Regional Gliding School óBesides lowering the combustion temperature, too rich a mixture will result in unburned wasted fuel. óIt contributes to fouled spark plugs and combustion chamber deposits. óCan also cause rough engine operation, appreciable loss of power or engine failure. óUsed for high power settings.

17 Regional Gliding School ÛMay cause rough engine operation, sudden “cutting out”, “popping back” or back-firing, detonation, overheating or appreciable loss of power. ÛContinual operation at too lean a mixture has also been responsible for engine failure. ÛUsed for cruise power settings.

18 Regional Gliding School When to Lean the Engine ¶At cruise power, below approximately 75% of the rated RPM of the engine. ·At any altitude above 3000 feet. ¸For take-off at high altitude airports. ¹After climbing to a higher altitude.

19 Regional Gliding School Why Lean the Engine Proper leaning of engine is both practical and economical. It results in: 4economy of fuel, 4a smoother running engine, 4a more efficient engine, 4extended range, 4less spark plug fouling, 4more desirable engine temperatures, and 4cleaner combustion chambers.

20 Confirmation Stage NOTE: You must use the buttons in the Confirmation Stage

21 Regional Gliding School Aero Engines Carburetor and Exhaust Systems A B C D Final approach Climbing at high altitudes Let's try a few review questions on Aero Engines: Question #2 - When do you lean your engine? Take off at low altitude Climbing at low altitudes

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26 Regional Gliding School Aero Engines Carburetor and Exhaust Systems A B C D Longer spark plug life Cleaner engine All the above Let's try a few review questions on Aero Engines: Question #3 - Why do you lean your engine? Extended range

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31 Regional Gliding School  Forms under moist atmospheric conditions with air temperatures anywhere from approximately -5  C to 30  C.  Indicated by a loss of power (RPM drop).  Can cause complete engine failure.

32 Regional Gliding School Forms of Carburetor Ice There are three forms of carburetor ice: –fuel vaporization ice, –impact ice, and –throttle ice.

33 Regional Gliding School Prevention of Carb Icing ‡Carb icing does not occur in engines that have fuel injectors rather than a carburetor. ‡Carb heat uses air heated by the exhaust system which is pumped into the carburetor. ‡Results in initial drop in RPM. ‡If ice is present, its melting will give a short period of engine roughness.

34 Regional Gliding School Exhaust System 2Basically a scavenging system. 2Collects and disposes of the high temperature, noxious gases discharged by the engine. 2Main function is to prevent the escape of these potentially destructive gases into the airframe and cabin. 2Two types: ¶short stack system, and ·collector system.

35 Regional Gliding School Short Stack Exhaust System õUsed on non-turbocharged engines and on low powered engines. õRelatively simple: áa down stack from each cylinder, áan exhaust collector tube on each side of the engine, and áan exhaust ejector on each side of the cowling.

36 Regional Gliding School Collector Exhaust System (Used on most large engines and on all turbocharged engines. (Individual exhaust headers empty into a collector ring that collects the exhaust from all the cylinders. (One outlet from this rings routes the hot exhaust gas to the turbocharger. (An exhaust tailpipe carries the gases away.

37 Regional Gliding School NOTE: You must use the buttons in the Confirmation Stage

38 Regional Gliding School Aero Engines Carburetor and Exhaust Systems A B C D -30°C to -5°C -30°C to 5°C 5°C to 30°C Let's try a few review questions on Aero Engines: Question #4 - At approximately what temperature range can carburetor ice form? -5°C to 30°C

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43 Regional Gliding School Aero Engines Carburetor and Exhaust Systems A B C D Collector Venturi Both B and C Let's try a few review questions on Aero Engines: Question #5 - Which is NOT a type of exhaust system? Short Stack

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48 Regional Gliding School Congratulations!! You have now completed the Carburetor and Exhaust Systems lesson of the Aero Engines Module. Of course, this lesson is always available to you for future reference if required. You are now ready to move along to the next Aero Engines lesson you have not completed or to any other module you wish. You can advance to the Self Test Module if you feel ready to challenge the final exam. Good Luck! Aero Engines Carburetor and Exhaust Systems


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