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26 Cards in this Set
- Front
- Back
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What does thrust generation rely on? |
The weight of the air consumed |
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What happens at high altitudes for jet engines? |
Thrust decreases due to less air but AS increases due to less friction |
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What are the advantages to Jet engines? (3) |
- Good thrust to weight ratio - few moving and intricate parts - reduced drag due to small frontal area and no propellers |
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What are the disadvantages to jet engines? (2) |
- consume large amount of fuel at low alts - slow to respond to application of power |
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Generally, at what height do turbojet engines achieve maximum efficiency? |
36000' |
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Generally, at what height do turbofan engines achieve maximum efficiency? |
33000 - 37000 |
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What advantages do turbofans have over turbojets? (4) |
- Greater fuel efficiency - quieter operation - better low alt performance - lower landing speeds |
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For turboprop, how much energy is derived from the propeller? |
90-95 % |
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How do turboprops differ from jets in terms of altitude and efficiency/ |
turboprops gain efficiency with altitude to a certain alt when it drops off due to lack of air volume |
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What are the common alts |
P - ground to 12000 tp - 13000 to 25000 j - 25000 and up |
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What are the common speeds |
p - up to 250 kt tp - 200 - 300 kt j - 300 -500 kt |
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What are the common climb rates |
p - 500 to 1500 ft/min tp - 1500 to 3000 ft/min j - 1500 to 6000 ft/min |
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What are the common rates of descent |
p - 500 - 1500 fpm tp - 1500 - 4000 fpm j - 2000 -6000 fpm |
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Do jet planes climb and descend at constant rates? |
no they climb at greater rates in lower alts they descend at greater rates in high alts |
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What are the common turn rates? |
p - Rate 1 (3° per min) tp - Rate 1 j - Rate 1/2 (1.5° per min) |
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What are the common run-ups |
p - long tp - short j - none |
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What are the common accelerations? |
p - short tp - short j - long |
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What are the common economies? |
p - very efficient at low alts tp - efficient j - less efficient |
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What are the common FOD (Foreign Object Damage)? |
p - does not ingest tp - does not ingest j - ingests |
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Define pitch |
The pitch, governed by the angle of attack, is the distance a propeller travels forward in one revolution |
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What happens if the blade is set at a large angle of attack? |
This COARSE pitch provides a greater effective distance for a given RPM |
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Define Fixed Pitch |
The pitch has been set by the manufacturer to give the best performance in all situations |
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Define Variable Pitch |
The pitch can be set by the pilot either on the ground (adjustable) or by controls in the cockpit (controllable) |
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Define Constant Speed pitch |
The propeller is a variable pitch propeller that is fitted with a governor that alters the blade angle to maintain RPM in all conditions |
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Define Reversible Pitch |
The propeller blades can be reversed pitched to push air instead of pull. As a safety feature, the extended nose wheel must be in contact with the ground to select Reverse Pitch |
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Define feathering |
The propeller blades can be rotated 90° |
