Fixed props

[Gludy]

As a mobo guy I want to know why you raggies mostly fix your props - do fixed props offer less drag?

 

[Joe_Cole]

Folding props offer less drag.

 

[Kilter]

cuts down on wear from the prop idly spinning as we cross mile after mile of ocean. with a fixed 3 blade prop probably doesn't make a lot of difference in terms of drag, folding prop does tho.

 

[bedouin]

There is a big debate about whether fixed or rotating props offer less drag.

More importantly a rotating prop can cause excessive wear to the gearbox - so many manufacturers recommend that the prop is locked for that reason.u

 

[Jezlyn]

A rotating prop offers more thrust.

 

[Gludy]

I have now found out that a prop lef to rotate acts as a stalled gyroscope and offers a lot of increased drag.

 

[BrendanS]

Depends on the prop. A helicopter has blades with huge diameter and little area, while mobo prop has small diameter, but huge area by comparison (don't start telling me helicopter blades have more area, I mean as a % of diameter) Many yacht props are more like helicopter blades than mobo as they frequently only have two or three blades of quite narrow chord compared to Mobo's

 

[Gludy]

Nope - as per discussion on MObo forum it does not depend on the prop - it is true of all fixed props.

In other words, ignoring collapsable props, the drag on a locked prop is less than the drag on a prop left to rotate.... always.

 

[Talbot]

Thats what I love about "scientists" - support the scientific study even when the empirical evidence suggests otherwise.

 

[john_morris_uk]

The only interesting part of this discussion is how often it comes round.

When I am really idle, I must do some research and find out the average time between arguments over prop drag on YBW!!

 

[Aardee]

Simple experiment - Get a childs "Beach Windmill". Try pulling it through the air with the "blades" fixed and then with the "blades" spinning...fixed offers less resistance every time.

 

[Clive_Rigden]

Priniple of the autogiro.

 

[Gludy]

All the evidence and measurement support the point.