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