PPRuNe Forums - View Single Post - Reduction of Condition levers
View Single Post
Old 30th December 2005 | 14:38
  #2 (permalink)  
error_401
 
Joined: Nov 2002
Posts: 198
Likes: 0
From: Heart of Europe
I don't think that the aerodynamic is that much of a concern.

IMHO (actually flying a turbo-prop)

Propeller design: Is made to offer a range in which the prop can steer to maintain a maximum rpm. Be it the take-off setting, be it a cruise setting. This means that the prop itself is not limited but could (with a more powerful engine) still produce more thrust.

Back to the inital question I think that as long as the prop is able to maintain its rpm in the design range it is compensating for the effects described.

Maximum thrust with a prop aircraft is at maximum torque.
Maximum torque is usually the limiter for turbo-prop aircraft (apart from other things like Nh [high pressure stage] or ITT).
The higher propeller rpm the more power you need to achieve the same torque at the prop. This is the main reason for the high setting at take-off where you want ALL that is available.

Once established in climb you reduce to a lower propeller rpm.
1st for comfort reasons.
2nd you lower the power output on the turbine or engine to below the MCT (maximum continous thrust/torque) to keep engine lifetimes high.

Maybe there is somebody else from the propeller guild who can be more specific.

error
error_401 is offline