Ducted prop

Just thinking whether a prop would be more efficient if it had a duct around it. I'm sure it's been done, but was wondering what the pros and cons would be.

Re: Ducted prop

If it was a viable solution for any particular problem the engine manufacturers would have done it long ago.

Re: Ducted prop

I imagine the drag and added weight of the duct would offset any gains.

Re: Ducted prop

I'm aware that it would be commonplace if it worked well. I guess I'm more asking about why it isn't an improvement. Drag I can see, but not really weight. What are other issues with it?

Re: Ducted prop

Ducted fans are used a lot in airplanes. The duct keeps the blade tips from losing air and increases efficiency. In fact, ALL commercial airline engines are jet engines driving a ducted fan. That's why they are so big in the front. The ducted fan increases the efficiency of the jet engine and the shroud of air exhausting out the back quiets the jet some.

Think of Berkely a water jet and the walls being the duct. The duct can easily be streamlined for minimum drag. I suppose the main reason they are not common in boat props is the added cost of manufacturing. AND---until proved beyond a doubt that ducted props are better, the buying public just won't go for the extra cost--it just doesn't have the charisima and sexiness.

A long time ago, one boat manufacturer mad a hull called a tunnel hull in which the prop was semi-enclosed by the U shaped tunnel ---so variations on the theme have been tried.

Re: Ducted prop

I was kinda thinking alon the lines of a ducted fan, but more of the difference between a ran fan alone, compared to a rad fan with a shroud. Not sure how much a prop loses at the tips though. Was also thinking about differences in the size of the leading opening, having it a little larger than the actual duct portion, but then drag would increase drastically too. Just thoughts I'm hoping to figure out without having to try anything. More curiosity than anything.

Re: Ducted prop

Wouldn't a ducted prop just be the same thing as a Jet Drive?

Re: Ducted prop

Groton-Seadog said:

Wouldn't a ducted prop just be the same thing as a Jet Drive?

Click to expand...

yes it would