AMT 287 Exam 1 Pt 2

Neglecting drag, how much power is needed to cause a 2500 pound airplane to climb at 1000 R2/mig

Express your answer in ft-lbs/min, watts and HP.

2500 lb * 1000 ft\= 2,500,000 ft-lb/min

(1 HP/33,000 ft-lb/min) * (2,500,000 ft-lb/min) \= 75.76 HP

(746 watts/ 1 HP)*(75.7 HP) \= 56,515.115 watts

Three minutes after take-off how much potential energy will the aircraft of Question \#1 possess (neglet remaining fuel in the tanks)?

2,500 lb * 1000 ft.min * 3 min \= 7,500,000 ft-lb

PE \= 7,500,000 ft-lb

solid, liquid, gas, plasma

states of matter

gasses fill their containers completely and liquids do not; gasses are highly compressible and liquids are not compressible

difference between gasses and liquids

fluid

a substance which changes its shape easily and takes the shape of the container

Show the value of temperature of the standard day atmosphere at sea level in four different units of measure.

1) 59˚ F

2) 15˚ C

3) 298.18 ˚K

4) 518.67˚ R

3rd class lever

What kind of a lever is your forearm?

3rd Class lever

What kind of a lever is a hydraulic wobble pump handle?

Inertia is the resistance offered by a body to the motion whereas momentum is the tendency of a body to continue moving.

What are the differences between inertia and momentum?

air

principal fluid for propulsion

thrust

the force which propels the aircraft

thrust horsepower (THP)

calculated by multiplying thrust by by aircraft speed (in MPH) divided by by 375 mi-lbs per hr or 325 kt-lbs per hr

How much thrust is being used by an atreraft that is using 100 THP to go 100 MPH?

X(100mph)/375 \= 100 THP

X\= 375 lbs of thrust

How much more or less thrust than the airplane of Question \#5 is another aircraft using that is using 100 THP, just like the airplane of Question \#5, but is going 90 KTS?

X(103.6)/375 \= 100 THP

X\=632.0 lbs of thrust

13.0 lbs less than Q \#5

The advantages of a hydraulic valve filter or tappets is that it automatically keep the value at 0, trapping the oil in the pressure chamber. Then, a predetermined leakage occurs between the plunger and cylinder, compensating for any expansion or contraction in the valve train.

What are the advantages of a hydraulic lifter?

cylinder head and cylinder barrel

parts in a typical cylinder assembly

cylinder head

provides a place for the combustion of the fuel/air mixture and gives the cylinder more heat conductivity for adequate cooling; made out of aluminum alloy

cylinder barrel

holds the piston; must be light and withstand high temperatures; made out of steel alloy

nitriding

steel of the cylinder barrel soaks up nitrogen for the gas which forms iron nitrides on the exposed surface

piston

act as a moving wall within the combustion chamber; draws in (down) and compresses (up) fuel/air mixture

dynamic damper

a pendulum fastened to the crankshaft that reduces vibration during engine operation

Chemical energy into heat energy into mechanical energy.

What three energy forms does the reciprocating engine utilize or convert?

ft-lb per min/33,000 or ft-lb per sec/550

Horsepower (HP)

brake horsepower (BHP)

work per revolution

On a short field takeoff, what can the pilot do to reduce FHP and thus increase BHP and THP?

Pull the alternator field circuit breaker, or open the alternator switch, and let the battery handle the electrical system until you've cleared.

reduce friction, act as a cushion in between metal parts, absorb heat, reduces abrasive wear, and cleans the engine

functions of lubricating oil

The oil selected must be light enough to circulate freely but heavy enough to provide the proper oil film at various temperatures.

Why is viscosity important when selecting a lubricant?

What is the relationship between aviation grade numbers and SAE numbers for lubricating oil?

The Society of Automotive Engineers (SAE) rates and divides the oils into specific groups that go hand-in-hand in aviation grade numbers.

Under what conditions would a dry sump system be advantageous, over a wet sump?

A dry sump would be better for radial engines because oil can't be carried inside the engine itself and wet sump systems are self-contained unit.

Some advantages of wet sump lubrication systems is that it is a complete system that requires no external parts, no second pump is required, and it can be operated in colder temperatures.

What are the advantages of a wet sump system, compared to the dry sump?

Displacement pump and mechanical positive.

What type of pump is the engine oil pump?

bypass valve

allows oil flow if the oil filter becomes plugged

relief valve

creates pressure in the system to compensate for wear on bearings or thinning out oil

The cylinder walls are lubricated by oil sprayed from the crankshaft and crankpin bearings.

How are the cylinder walls lubricated in a typical opposed aircraft engine?

The cowlings are designed to force air over the cylinder cooling fins.

How does the cowling contribute to engine cooling?

augmenter tube

provides additional cooling, especially for low speed, high power conditions

How does opening cowl flaps affect engine cooling? Cabin cooling?

For engine cooling, cowl flaps (when opened) increase cooling airflow over the engine and through the oil cooler. For cabin cooling, hot and cold airflow is reduced due to air pressure inside and in front of the cowling when cowl flaps are open.

Rotational velocity

w \= 2pi(rpm)/60s \= unit ft/s

ft/s x 0.592 KTS \= unit KTS

KTS x 0.0015 Ma \= unit Ma

tan \= forward velocity/linear velocity

tan-1 to get degrees

near the tip to provide equal thrust along the propeller blade

where is the lowest blade angle!

With a fixed RPM, does propeller blade angle of attack increase or decrease as airspeed increases?

The angle of attack decreases while the blade angle increases.

centrifugal twisting force

force that tends to twist the blade to decrease propeller angle

Aerodynamic twisting force

force that tends to twist the blade to increase propeller blade angle

1) propeller position for hand starting

2) intake/exhaust valve opening minimized

3) less attractive for birds to perch on

What are the advantages of leaving the propeller in the 10/4 o clock position?

static balancing

propeller suspended by a drawstring

dynamic balancing

an electrical machine with vibration analysis of the aircraft

ground-adjustable propeller

operates as a fixed-pitch propeller; only can be changed on ground

two position propeller

permits a change of blade pitch while the prop is rotating

What components in the governor oppose the force of the speeder spring?

The flight weight and the pilot valve.

centrifugal force

force used to feather a propeller

carburetor venturi

provides the low pressure at the discharge nozzle of a float carburetor

Main metering jet

limits the maximum amount of fuel which can flow from the float bowl for any given pressure differential

1) to improve fuel vaporization

2) to provide a more even mixture over a wide range of air flows

3) to decrease the size of the fuel metering force needed which decreases the amount of restriction necessary at the Venturi

functions of an air bleed on a float carburetor

1. fuel evaporation
2. decreasing air pressure in the venturi

Why are float carburetors more susceptible to icing?

When should carburetor heat be used on the ground (several answers)?

When engine starting in high or low temperatures and when shutting off the engine which prevents cold air from passing through

What is the purpose of the acceleration system on an aircraft carburetor?

temporarily enriches the mixture when the throttle is suddenly opening

Why is a power enrichment system also called an economizer system?

Because they allow the engine to operate with a relatively lean, economical mixture for all conditions besides full power

it will be leaned when the air bleed is restricted

Is the fuel-air mixture enriched or leaned when the main air bleed is restricted?

richen

Does application of carburetor heat richen or lean the mixture?

a) less dense air decreases the amount of oxygen getting into the cylinder, thus increasing the fuel/air ratio

b) higher air temperature will do a better job of vaporizing the fuel, thus increasing the fuel/air ratio

1. not susceptible to icing
2. even fuel/air mixture distribution
3. not critical at high density altitudes
4. not affected by gravity

advantages of the pressure carburetor over the float carburetor

less susceptible to icing, but can still have ice formations

disadvantages of the pressure carburetor

air pressure

What does the fuel flowmeter actually measure on the fuel injection systems discussed in this chapter?

air bleed

minimizes fuel bleeding in fuel injection systems

What are the functions of the spider?

1) distributes the fuel evenly to all of the cylinders

2) provides a positive shut off when the mixture control is placed in the idle cut off position

not susceptible to icing and has more power than carbureted systems

What are the advantages of a fuel injection system, as a fuel metering system?

possible vapor lock in the fuel lines make it difficult to start the engine

What are the disadvantages of a fuel injection system, as a fuel metering system?

True

T/F. An in-line engine usually has an even number of cylinders. This engine may be either liquid cooled, or air cooled and has only one crankshaft, either above or below the cylinders.

T/F. The opposed type of engine has two banks of cylinders opposite each

other with a crankshaft in the center. This type of engine may be liquid cooled or

air-cooled but the air-cooled version is used predominantly in aviation today.

True

T/F Radial engines consist of a row or rows of cylinders arranged radially about

a central crankcase. The number of cylinders comprising a row may be three, five

or seven or nine, but it is always and odd number.

True

compression rings

prevent the escape of gas past the piston during engine operation

oil control ring location

placed in grooves immediately below the compression rings and above the piston pin bore

oil control rings

regulate the thickness of oil film on the cylinder wall

oil scraper ring

usually has a beveled face and is installed in the groove on the bottom of the piston skirt

lower

intake valves operate at _____ temperatures than the exhaust valves

1/2

The camshaft always rotates at _____ the crankshaft speed in four stroke engines

plain, ball, roller

three types of bearings commonly found in engines

the speed of sound; decreases

when the propeller tips approach ____, the efficiency of the propeller _____ rapidly

tapered, splined, flanged

three major types of propeller shafts

single-throw, double-throw, four-throw, six-throw

four principle types of crankshafts

bearing

any surface that supports or is supported by another surface.