Aircraft Instrumentation - Engine Instruments

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Buffalo Six
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Joined: 11 Jul 2002, 17:26
Location: Wichita KS

Aircraft Instrumentation - Engine Instruments

Post by Buffalo Six » 03 Dec 2008, 08:17

After last nights mission and listening to some of the problems people were having, I have decided to post some items that may help you guys get more out of the planes we fly.

This is from the flight training section over at the 352nd VFG that I also am flying with. Rambling Jack is the training guy and he's a current charter pilot flying in Nevada. Its good advice and has helped me get more out of the planes. The following was written by him.

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Aircraft Instrumentation – Engine Instruments

This discussion will deal with engine instruments that are unique to aircraft. The main differences being aircraft that are liquid cooled and those that are air cooled, and aircraft that are equipped with a fixed pitch propeller and those that have a constant speed propeller. The other difference to be discussed will be the difference between a turbo supercharged airplane and one that is supercharger.

Liquid cooled vs air cooled engines

The P-40 engine is liquid cooled and as the name would imply the engine is cooled much the same way any modern day automobile would be cooled. The engine is surrounded by a coolant jacket that circulates coolant around the engine drawing off the heat. The coolant is then routed through a radiator that cools the coolant and re-circulates it around the engine. By adjusting the position of the radiator door opening you can regulate the amount of cooling provided to the engine. That big nose inlet, that gives the P-40 its distinctive look, is the coolant radiator. If you look at the underside of the airplane, just ahead of the leading edge of the wing, you will see the doors that operate allowing you to open or close them to regulate engine cooling. On the P-51 you will notice the radiator door on the bottom of the airplane aft of the trailing edge of the wing. Instrumentation used to monitor the temperature of the engine is primarily the coolant temp gauge. Oil temperature, to a lesser degree, is also used to monitor engine temperatures.

On an air cooled engine, the P-47 for example, the engine is cooled by air passing through and around the vanes on each cylinder. By opening and closing the cowl flaps, that’s the ring of little doors that surround the aft portion of the engine cowling, you regulate the amount of air passing through the engine cowling thus regulating the amount of engine cooling. The system is very simple yet very effective. Instrumentation used to monitor the temperature of an air cooled engine is primarily the cylinder head temperature (CHT), and of almost equal importance is the oil temperature. Oil in an air cooled engine is usually measured in gallons not quarts. In addition to lubricating the engine, the oil draws off much of the engine heat and cools the engine by passing through an oil radiator. Many an air cooled radial engine pilot has stopped for fuel and jokingly told the attendant to “top the oil and check the gasâ€

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