Lecture 2- Reciprocating Engines

How does liquid cooling work?

- Cooling liquid is circulated through the engine areas that require heat removal - Heat is transferred to the liquid - Heated liquid then passes through a heat exchanger (radiator) and cools down - Cooled liquid is cycled back into engine to repeat process

Radial Engines disadvantages:

- Lowest weight to horsepower ratio of all reciprocating engines - Large frontal area creates lots of drag

Rotary Disadvantages:

- Torque and gyro effect of the engine's large rotating mass make aircraft difficult to control - Castor oil was used as the engine lubricant. The castor oil fumes from the engine's exhaust was often nauseating

Advantages (and disadvantage) of Air Cooling:

- Weight of an air cooled engine is usually less than a liquid cooled - Less affected by cold weather operations Less vulnerable to gunfire - (Disadvantage) Requires forward movement for ram air to sufficiently cool the engine

What type of engine cooling is this? - Removes excessive heat by the convection process - Thin metal fins known as cooling fins projects from engine cylinders - Baffles used around the cylinders to direct the air flow

Air Cooled

Name the Engine: - Resembles two single-row radial engines on a single crankshaft - Cylinders range form 14-18 - The Cylinders are staggered

Double Row Radial Engine

Name the Engine: - cylinders are arranged in a row parallel to the crankshaft - Cylinders can be above or below crankshaft - Even number of cylinders preferred for balance

In-Line engines

What is it called when the cylinders of a V-Type engine are below the crankshaft?

Inverted V-Type

Engine Designations: L- T- I- G- S- O- R- 470-

L- Left-Hand Rotation T- Turbocharged I- Fuel Injected G- Geared S- Supercharged O- Opposed Cylinders R- Radial Engine 470- Displacement to the nearest

What type of Engine cooling is this? - Not commonly used in the US today - Consists of passage around the cylinders and specific hot spots in the engine - A radiator to cool the liquid

Liquid Cooled

Name the Engine: - Used towards the end of WW2 - The largest and most powerful reciprocating engine - Replaced by gas-turbine engines

Multiple-Row Radial Engines

Name the Engine: - Most popular for light conventional aircraft and helicopters Most efficient and economical for light aircraft - Mounted with the cylinders and the crankshaft horizontal

Opposed (Flat) Type Engine

Name the Engine: - Crankshaft is held stationary to the engine mount - Cylinders rotate about the crankshaft - Propeller is attached to the engine case

Rotary

Name the Engine: - Odd number of cylinders extending radially from the centerline of the crankshaft - Cylinders range from 5-9 - All pistons are connected to a single throw 360 crankshaft

Single-Row Radial Engine

What is it called when the cylinders of a V-Type engine are above the crankshaft?

Upright V-Type

Name the Engine: - Cylinders are arranged in two rows, forming the letter V - Angles b/w 90, 60, or 45

V-Type