Seawolf Class Propeller

[libord]

They call them propulsors in

They call them propulsors in this shroud settup.

Figuring this is not that difficult, but believe what you want.




Pete

Well, just draw the lines is not that difficult, that was first thing I did yesterday, however, I think your sketch proves opposite - see that each of your lines acually start at different point on the blade. So it seems it doesn't work with 6 blades. See the next [linked enlarged] image. I circled (green circles) 3 very well visible equal points on 3 top blades. Than I tried to find center (I guess didn't get it precisely) and connect them to the center. The result shows, that the 3 top blades are too close to each other for a 6-blade setup.


(click to enlarge)

Also, yesterday night I digged into available materials and found out, that all (all of those I came across) american main stream submarines after Nautilus had 7-blade propellers.

Anyway, all the comments are welcomed and thank you for them. I'm glade to see so many posts!

Regards,

[anonymous]

Pete,
Your lines don't match up

Pete,
Your lines don't match up tip to tip, nor do they intersect the shaft centerline.
When I say 7, I'm just going off of many years of looking at different prop shapes from all angles.
As you say, you can believe what you want...



Chris

[pirate]

Well, ya know. I ran

Well, ya know. I ran this through my calculus-trigonometry disgronificator last night, and it says there are 34 blades in this picture. Now it may be counting those on the other boats being built in this building, but you just never know.

[Rogue Sub]

Well, ya know. I ran

Well, ya know. I ran this through my calculus-trigonometry disgronificator last night, and it says there are 34 blades in this picture. Now it may be counting those on the other boats being built in this building, but you just never know.

Yeah I just used mine aswell and it came up with 187. Maybe its the picture?

[pirate]

Kevin,
You just toured a Virginia

Kevin,
You just toured a Virginia Class, didn't you? I bet you could help with this question. I know you can't say how many blades it has, but is it a number that divides into 28 or 36?

[Rogue Sub]

Pete,
Sorry bro cant tell you.

Pete,
Sorry bro cant tell you. They work really goof though

[pirate]

Oh, I knew you couldn't

Oh, I knew you couldn't tell. I was just being silly. But "do" you know?

[Rogue Sub]

Well I asked lots of

Well I asked lots of questions while onboard. I could tell you what most of the surface detail on your nice model is. Ofcourse id make you give me one first!

[talwar]

Looks like a 7 blade

Looks like a 7 blade to me.

The odd numbers (not just prime numbers) has to do with the rudder. You don't want two blades to get out of the "shadow" of the rudders at one moment. If you have an odd number of blades, you always have just one blade getting out of that wake. If you have two blades doing that at one time, you get a rough vibration, which is bad for the noise signature.

The only 6-blade propellor sub I know of up till now is the original Kilo. That one doesn't have an upper rudder, so the odd number argument doesn't count for them. More blades also means a better division of the pressure around the propellor, which adds to the silence too. Up till now 7 blades is the maximum though, strength issues.
I do however not think this applies to a pumpjet, because there the propellor is not entirely behind the rudders, there are some stators between them after all.