Alrosa PJ Round 3

[bigdave]

Well it’s the third attempt to get the thrust up in the Alrosa Pump Jet.
Ain't experimenting fun!!
This time I made a long shaft PPJ impeller and cut it down to fit in the shroud.
This meant removing most of the blade area and modifying the bearing mount to get some more room inside for the longer impeller.

I also added a rear bearing. This is not to keep the shaft aligned but rather to center the shroud on the shaft. It also gave me the do hicky (very technical term) on the end of the pump to make it look scale. I did some laundry tub tests and it is pushing more water. I will try it out this weekend at our next fun run. I think I am on the right track and if this is not quite enough thrust I can cut back a little on the rear bearing mount so I can make the impeller a little larger. Stay Tuned. BD.

[pirate]

Dave,

That looks promising.

You might try

Dave,

That looks promising.

You might try curving the front edges of the blades.



Also, the former jet engine engineer (brain fart) Mr. Meyer (I can't think of his first name. Was it Chip?), told me that the key to an efficient prop is a clean curve on the forward facing side to produce pull (or lift like an airplane wing). It looks from the photos like that side of yours, especially towards the root, are not a clearly defined foil. He said a prop actually pulls a boat when it seems like they are pushing it.

Pete

[bigdave]

Thanks for your feedback Pete.

Thanks for your feedback Pete. If this does not work I will try reshaping the impeller before I make a larger one. BD.

[pirate]

Dave,

Hope to help, but my

Dave,

Hope to help, but my advice isn't worth any more than it costs.

Pete

[bigdave]

Well the test went well.

Well the test went well. I definitely had more speed.
But I still think I can squeeze a bit more out of her. I will check the video and post some if it came out. BD.

I posted some video in the video section. BD.