Lecture 2 - Reciprocating Engine Classification

What are 2 disadvantages to radial type engines?

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

On in-line engines, cylinders are usually limited to how many cylinders, to aid cooling and avoid excessive weight?

6

_______________ are used around the cylinders to direct the airflow and obtain maximum cooling for the engine

Baffles

Letters are employed to indicate __________________

Characteristics

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 The cooled liquid is then cycled back into the engine to repeat the cooling process

_________ is held stationary to the engine mount

Crankshaft

____________ rotate about the crankshaft

Cylinders

Numbers are employed to indicate __________________

Displacement

Engine Designation: #

Displacement to the nearest 5 inches cubed

What kind of engine has a two-throw 180° crankshaft, used to allow stagger between each row of cylinders?

Double Row Radial Engine

What kind of engine resembles two single-row radial engines on a single crankshaft?

Double Row Radial Engine

An __________ number of cylinders are preferred for proper balance on in-line engines

Even

There are always a(n) ______ number of cylinders per row on V-Type engines

Even

Engine Designation: I

Fuel Injected

Engine Designation: G

Geared

Cylinders below the crankshaft of an In-Line Engine is called _____________

In-Line Inverted Engine

WWI in-line engines are typically __________.

Inverted

What do you call a V-Type engine when the cylinders are below the crankshaft?

Inverted V-Type Engine

What are a couple disadvantages of a radial engine?

Large frontal area creates a lot of drag, cooling problems

Engine Designation: L

Left hand rotation

Liquid cooling system consists of:

Liquid passage around the cylinders and specific hotspots in the engine Radiator to cool the liquid Thermostatic element to decide amount of cooling to the liquid Connecting pipes and hoses Relief valve to prevent excessive pressure

What are 3 benefits of Opposed and Flat Type Engines?

Low weight-to-horsepower ratio Flat shape is very easy to streamline Reasonably free from vibration

Why are Opposed and Flat Type Engines best for light aircraft?

Most efficient and economical

What kind of engine is the largest and most powerful reciprocating engine?

Multiple Row Radial Engine

Radial engines always have a(n) _____________ number of cylinders

Odd

What kind of engine is most popular for light conventional aircraft and helicopters?

Opposed and Flat Type Engines

What type of engine is mounted with the cylinders and the crankshaft horizontal?

Opposed and Flat Type Engines

Engine Designation: O

Opposed cylinders

This kind of engine has the lowest weight-to-horsepower ratio of all reciprocating engines

Radial Engine

Engine Designation: R

Radial engine

What kind of engine powered many WWI aircrafts?

Radial engines

Multiple Row Radial Engines were replaced with what? Why?

Replaced by gas-turbine engines; More powerful and lightweight, Fewer moving parts, TBO greatly increased

What is a disadvantage of air cooled engines?

Requires forward movement for ram air to sufficiently cool the engine

Types of Radial Engines:

Rotary-Type Radial Engines In-Line Engines V-Type Engines Radial Engines Multiple-Row Radial Engines Opposed and Flat Type Engines Others

What kind of engine has all pistons connected to a single-throw 360° crankshaft?

Single Row Radial Engine

Engine Designation: S

Supercharged

Engine Designation: T

Turbocharged

What are the typical angles between the rows of V-Type engines?

Usually 90, 60, or 45°

The frontal area on _____________________ is only slightly greater than in-line engines

V-Type Engines

What kind of engine has cylinders arranged in two rows, forming the letter V?

V-type engine

What are some advantages of air cooled engines?

Weight of an air cooled engine is usually less than a liquid cooled engine, Less affected by cold weather operations, Less vulnerable to gunfire (Military)

When is the V-Type engine considered an "Upright V-Type Engine"?

When the cylinders are above the crankshaft

There are more __________ cooled engines than ___________ cooled engines

air cooled, liquid cooled

Thin metal fins known as ___________ project from the engine cylinders to help cool the engine

cooling fins

On in-line engines, ____________ can be above or below (inverted) the crankshaft

cylinders

Cylinders of a(n) ____________ engine are arranged in a row parallel to the crankshaft

in-line

In-line engines are harder to cool as they ____________________

increase in size

In-line engines were largely used for _____________ and ___________ horsepower applications

low and medium

In-line engine's small frontal area allows for _________________________.

streamlining and low-drag nacelles