Engines & Airframes > Engine Types and Construction(Reciprocating Engines) > Flashcards

Engine Types and Construction(Reciprocating Engines) Flashcards

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1
Q

Why is it called a heat engine?

A

Because we are using the expansion of heat to make our engines run

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2
Q

How do we divide and categorize heat engines?

A
  1. The working fluid used in the engine cycle
  2. The means by which mechanical energy is transmitted into propulsive force
  3. The compression method for the working fluid
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3
Q

What is a reciprocating engine?

A

Piston engine (we call it reciprocating because the pistons are reciprocating)

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4
Q

What is a turboprop engine?

A

It takes a turbine engine and connects to a propeller

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5
Q

What is a turbojet engine?

A

An engine that uses a turbine to push air, creating thrust to push the plane forward

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6
Q

What is a ramjet?

A

An engine that relies on air compression and the movement of the aircraft to “ram” the air into the engine for compression

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7
Q

What is a rocket engine?

A

An engine that works by expelling mass (typically some high-temperature gas)

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8
Q

What must be considered when building an aircraft engine for sustainability?

A

-Engine weight
-Engine size
-Fuel available
-Thrust produced
-Efficiency
-Economy
-Reliability
-Mission type

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9
Q

What must be considered when selecting engine size?

A

-Weight
-Power created
-Pilot view
-Drag
-Efficiency

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10
Q

When selecting an engine, what design features should we consider?

A

-Fuel consumption
-Speeds
-Size
-Turbo/supercharged
-Engine design
-Altitude and speed requirements
-Fuel type

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11
Q

What do you need for an engine to work?

A

-Gas
-Air
-Spark (at least to start it)
-Place for everything to happen
-Method to use the motion created by the burns
-Method to dispel excess heat
Note: All these things have to happen at all altitudes and flight conditions

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12
Q

What engine is more fuel-efficient at low speeds?

A

Reciprocating (Needs less air)

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13
Q

What engine is more fuel-efficient at high speeds?

A

Turbine (Needs more air)

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14
Q

What is durability?

A

Amount of useful engine time while maintaining desired reliability

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15
Q

What is reliability?

A

The ability of the engine to do its job without failing

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16
Q

What does TTSN mean?

A

Total time since new

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17
Q

What does TBO mean?

A

Time between overhauls

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18
Q

What does overhaul mean?

A

An overhaul is when an engine is completely disassembled, cleaned, and inspected to identify and replace worn and damaged parts

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19
Q

What factors affect the need for overhaul?

A

The demands/tasks that the engine is subjected to

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20
Q

What are the 4 reciprocating engine types?

A
  1. In-line
  2. Opposed
  3. V-engine
  4. Radial engine
    Note: Essentially, these are the many ways to configure and position the cylinders
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21
Q

Why is an in-line engine called that?

A

Because the cylinders are all arranged in a line

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22
Q

Why is an opposed engine called that?

A

The cylinders are positioned as if they are mirrored on 2 sides. They fire directly opposite to each other

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23
Q

Why is a V-engine called that?

A

The cylinders are positioned so that they fire in a “V”

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24
Q

Why do we call radial engines that?

Study These Flashcards
A

Because the cylinders are arranged like flower petals (around the center). It fires around almost like a clock’s needle

25
How does a reciprocating engine operate?
1. Intake valve opens up 2. Piston comes down to create a low-pressure zone, which draws air in. Once done, the intake valves close. 3. Piston comes up to compress the fuel and air mixture 4. Spark lights up the fuel-air mixture and leads to combustion (this is the power stroke) 5. The exhaust valve opens up after combustion is complete to expel the waste
26
What are the 4 strokes of a reciprocating engine?
1. Intake 2. Compression *Spark* 3. Combustion 4. Exhaust
27
What is the purpose of the crankcase?
The crank case houses the crankshaft, which transfers straight motion into circular (for propellers and wheels) +Supports +Lubricates
28
What is the crankcase typically made of?
Aluminum alloy, but it could occasionally be steel. Aluminum is lighter and CAN be strong if pristine. But steel is generally stronger and is more tolerant of heat
29
What does the crankshaft do?
It turns straight motion into circular motion
30
What connects the piston to the crankshaft?
The con rod(connecting rod)
31
How does a connecting rod connect to the piston?
It sticks to the bottom of the piston using a pinhole with a pin in the hole to hold it together
32
What is the piston?
The component that moves up and down in a cylinder
33
What are piston rings, and why do we need them?
They are metallic split rings attached to the outer diameter of the piston. We need it to seal the combustion chamber (by plugging the space between the piston and cylinder)
34
What do spark plugs do?
Connects the spark wire to the cylinders and sparks the combustion phase of the engine
35
How many valves are in most aviation cylinders?
2 per cylinder (1 for intake, 1 for exhaust)
36
What position are valves in automatically?
Closed. We have to do something to open it up
37
What is valve lift?
The maximum height at which the valve is lifted off its seat
38
What is valve duration?
The amount of time the valve stays open during a crankshaft's rotation
39
What is valve overlap?
The small duration of time when both the intake and exhaust valves are open simultaneously.
40
Is valve overlap a good or bad thing?
It is a good thing because it allows the engine to function more smoothly
41
What does the cam have to do with valves and engine operations?
The cam has a node that rotates and pushes a push rod, which activates the rocker arm that opens the valve
42
What is a camshaft?
A shaft with one or more cams attached to it, especially one operating the valves in an internal combustion engine
43
What is a cam ring?
A circular component with internal surfaces that consists of grooves/nodes that drive the puming motion of the push rod as the cam rotates
44
What is a magneto?
A generator that uses permanent magnets to produce periodic pulses of alternating current
45
How does a magneto work?
-The primary coil creates a buildup of magnetic charge. -The secondary coil builds it up, and at the right time, it creates a current that jumps the gap in the plug, thus creating a spark in the plug
46
Do magnetos use battery power?
Yes, but ONLY to start. Once the starter retracts, the magnetos run independently of the plane's electrical system, creating their own spark
47
Why do we test that magnetos will ground?
So that we can ensure the engine won't start from simply turning the propeller
48
How do you know if a magneto is not grounded?
When you're doing magneto checks and the RPMs don't drop. Then you have a live prop. Park that plane as far from everyone as possible and call Ed
49
What is Top Dead Center? (TDC)
As far up as the piston goes
50
What is Bottom Dead Center? (BDC)
As far down as the piston goes
51
What is a stroke of the cylinder?
The distance from the Top Dead Center and the Bottom Dead Center
52
What is the bore of the cylinder?
The inside diameter of the cylinder
53
What does displacement refer to?
It describes how much "stuff" we can move in and out of the cylinder. It is the comparison of the volume of space available from when the cylinder is at BDC to when it is at TDC
54
What is a compression ratio?
It describes the bore in a mathematical sense
55
In theory, what does a higher compression ratio indicate?
It indicates high efficiency
56
What is manifold pressure?
The average pressure of the fuel-to-air mixture (or just air pressure if the engine is fuel-injected) charge in the intake manifold
57
Why would we number cylinders in an engine?
To know the firing order of the cylinders
58
How do we number cylinders?
In the order in which they fire. Usually, they fire from the front to the back. Where the FRONT is always the propeller side and the back is the accessory side.
59
What part of the valve does the rocker arm connect to?
The tip
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