TurboProp Flashcards
Turboprop most efficient operating speed
300-450mph
How much total power can turboprop engines extract
95%
What’s the name of a core engine
Gas generators or gas producer
What is gas couple free turbine
No mechanical connection between gas generator and free power turbine
What does propeller brake do
Prevent movement during aircraft loading when engine shut down not desired
What happens when fuel flow changes in gear direct
Propeller pitch changes to maintain constant speed
What’s constant at normal conditions gear/direct couple turbines
Propeller and fuel flow
What’s different between gas/couple and gear/direct
Gear/direct has extra turbine discs
What’s difficult about gear/direct
Needs complex integrated propeller control system to adjust propeller pitch
How do turbo prop differ to turbo jet
Turbo prop fly’s at Lower speeds but more hostile environments
What do inlet lips need
Large radius
What does a particle separator do
Protect compressors by prevent ingress of dirt ….
At what aircraft type has higher reduction ratio turbo prop or piston engine
Turboprop
Pratt & Whitney reduction ratio
15:1
33000 rpm how fast is the propeller rotating
200 rpm
Why does turboprop need higher viscosity lubricants
Heavier loads on imposed engines
What’s the problems with spur gears
Bulky and noisy & turbine shaft is offset
What’s used to overcome spur gears
Spur epicyclic gears that give output drive on the same axis as the input shaft
What’s a bevel epicyclic gear
Use bevel pinion (planet) gears
Where are bevel epicyclic gears used
Piston engines
What does the helical cut in spur epicyclic do
Reduce noise and vibration while providing a way to measure torque
What is a spur epicyclic gear
Pinion gear rotates around a sun gear inside an annular ring gear
What’s an advantage of compound spur epicyclic
Two stages high and low to provide greater speed without without needing larger components
What does the low speed train have
Helical gears
What does the high speed train have
High speed pinion
What is rotating annulus
Rotates propeller in the opposite direction to which engineer is rotating
What is variation in a compound spur epicyclic
Fixed annulus which rotates in the same direction as engine
What is a two stage spur
Single input/output gear unit contained in triple housing
What does input housing contain in atwo stage spur
First stage reduction gearing
What is the single input/output manufactured from
Magnesium alloy
Purpose of over speed saftey device
Used in first instance to coarsen blade angle if it fails then to reduce engine power
What are the methods of over speed safety devices
Engine governer & free power turbine , over speed governor
Why would an overspeed governer be re-datumed
Ground test purposes
What is twin lever control components
Power lever & conditioning lever
What does a power lever do
Control for engine power output in propeller constant speed mode & propeller blade angle directly in beta mode
What is the propeller conditioning lever used for
Set propeller rpm in constant speed mode
What is used to adjust propeller pitch in a single lever control
Complex control system
What is engine power dependent on
Mass and temperature of gas flow into turbine
