What is windmilling in aviation?

What is windmilling in aviation?

Windmilling refers to the aerodynamic effect that causes an idle fan or a pinwheel to rotate when air flows across its blades.  Now apply this in principle to an aircraft engine fan.

What does a windmilling propeller mean?

Windmilling Propeller. A propeller that is rotated by air flowing over the blades rather than powered by the engine.

What is feather in aviation?

Description. On many variable pitch propellers, the blade pitch can be increased to the point that the chord line of the blade is approximately parallel to the on-coming airflow. This process is referred to as feathering.

Does a windmilling propeller produce thrust?

As long as the AoA is positive, spinning the propeller by applying engine torque will create thrust.

Why does a windmilling propeller create more drag?

A stopped propeller is stalled and so creates a small amount of torque to “spin” the aircraft. It’s drag is small as the surface blade area is small. A windmilling propeller will not stall, so the energy extracted could be much more.

What is blade shank?

Blade Shank. The rounded portion of a propeller blade between the root and the airfoil section.

What is the difference between FADEC and EEC?

An EEC, though a component of a FADEC, is not by itself FADEC. When standing alone, the EEC makes all of the decisions until the pilot wishes to intervene. FADEC also controls engine starting and restarting. The FADEC’s basic purpose is to provide optimum engine efficiency for a given flight condition.

Does Boeing use FADEC?

Introduced in 1989, our FADEC 2 models were built for both narrow and wide-body aircraft manufactured by Boeing and Airbus. The FADEC 2 is produced and supported by FADEC International, a joint venture between BAE Systems and Safran.

What is the purpose of counterweights on a propeller?

Variable pitch propellers have either counterweights or a lock to limit unwanted blade angle movement to low pitch after failures. Counterweights are attached to the blade at a position that will cause the centrifugal loads on the counterweights to drive the blades towards higher pitch (towards feather).

Does a windmilling prop cause drag?

A windmilling propeller creates much more drag, by an order of magnitude at least. The obvious example is an autogyro or helicopter in autorotation, which drops like a stone if the rotor stopped. Drag is a function of blade area for a stopped rotor and a function of disc area for a windmilling one.

What is feather position?

Feather. Feather is employed if an engine must be shut down. In feathering, the blades are turned so that the leading edges are pointed essentially in the direction of flight. In this position, the aerodynamic forces on the propeller result in a low drag condition. Pitch lock.

How does windmilling work?

Windmilling typically happens when the gas turbine engine flames out, and at this time, the engine spool is powered by the momentum of the incoming airflow, just like the effect on a windmill.

Is there a windmilling model for a TBCC engine?

However, the absence of the windmilling model might cause critical problems unconsidered at the control system design stage and increase the risk of mission abortion. This paper provides a method of modeling the windmilling operation of a TBCC engine.

What direction does the propeller rotate when windmilling?

When windmilling, the propeller rotates in the same direction as when propelling the aircraft. Picture above was also included in this answer, and shows the local Angle of Attack at the blade profile: a vectorial summation of rotational speed of the prop, and airspeed.

What is the turbine engine model appendix?

This appendix outlines the turbine engine model descriptive information that should be submitted in order to establish those features of the engine that are involved in the certification and safe operation of the engine. 2. DISCUSSION.