JETPILOT From United States of America, joined May 1999, 3130 posts, RR: 29
Reply 1, posted (12 years 3 months 3 weeks 4 days 14 hours ago) and read 4688 times:
On any constant speed prop airplane the thrust levers control power output, and the prop levers allow selection of prop RPM.
The thrust levers only control the angle of the prop indirectly by way of the prop govenor to the extent needed to keep a constant RPM. The angle of the balde will change by way of the prop govenor when the thurst levers are moved the RPM will not.
The power turbine, and the prop only turn at the same RPM on a direct drive turboprop. Some turboprops are gear driven.
B1C17L1011 From United States of America, joined Jun 2001, 96 posts, RR: 0
Reply 2, posted (12 years 3 months 3 weeks 4 days 8 hours ago) and read 4646 times:
Yes, Thanks JET
In addition I would like to know; How are the thrust levers and the prop levers adjusted in relation to each other. Are the prop levers infinitely variable, or do they have specific settings? Also, are most large turboprop aircraft of the "constant speed" type.
Metwrench From United States of America, joined Aug 2001, 750 posts, RR: 2
Reply 5, posted (12 years 3 months 3 weeks 2 days 10 hours ago) and read 4550 times:
Speaking for TPE-331's, The prop governor maintains RPM. It does by so varying the pitch of the prop. Advance the power lever, the engine fuels "up" and tries to increase in RPM. The prop gov responds by increasing pitch which slows down the RPM. Meanwhile the increased fuel flow is allowing the prop to provide more positive thrust.
RPM is selected by the position of the "speed lever". Basically, there are 3 positions; ground idle (72%); Take Off 100%; Cruise 97%. The only time the speed lever is used is to transition between modes of flight.
Android From Japan, joined Jun 2002, 80 posts, RR: 0
Reply 6, posted (12 years 3 months 3 weeks 2 days 8 hours ago) and read 4535 times:
On the Dash-8 The Power Lever (PL) controls the engine RPM in the forward power range and controls Blade angle in the idle thru reverse "Beta" range.
Engine RPM and Prop RPM in Beta by the Fuel Control-HMU/MFC and the Engine Control Unit(ECU) fuel Schedule.The Condition Levers(CL) are used to set Prop RPM in the forward thrust range and provide manual prop feathering and fuel on/off control for Engine Start/shutdown.
Takeoff on the Dash-8 Props are set to Max (1200 RPM) and then brought back to usually 1050 on the climb and 900 during cruise for cabin comfort.
Then usually during final approach they are brought back to 1200 for better response and possible go-around.Power is adjusted to airspeed rate of descent as required
The New Dash-8 400 uses full electronic Engine and Prop controls (Throttle by wire).
Broke From United States of America, joined Apr 2002, 1322 posts, RR: 3
Reply 8, posted (12 years 3 months 3 weeks 1 day 23 hours ago) and read 4503 times:
Turboprop powered aircraft have two operating modes, Beta and flight. In the Beta mode, which is on the ground, the engine speed is variable according to power lever (not throttle, those are for reciprocating engines) angle. In flight the propeller is in the constant RPM mode and the propeller angle is varied by changing the power lever angle. Most later turboprops are totally constant speed, i. e. once you go into the flight mode on take-off the prop RPM is constant. On Rolls-Royce Dart powered airplanes, there is a different prop RPM for different flight modes, i.e. climb, cruise, descending. These airplanes are more difficult to ground run after engine changes and while trouble shooting in order to determine if the engine prop combination are operating OK.