What exactly is a pumpjet propulsor?

Deathblow · 09-16-05, 06:01 PM

How is a "pumpjet propulsor" different than any other regular propellar? I see that its shrouded, but other than that what's the difference?

Can anyone explain it to me? Did a google search and came up with nada.

Kapitan · 09-16-05, 06:04 PM

you ever looked inside a jet engine ? if not it has tiny thin fan blades so instead of 5 or 7 blades you might have 70 or 80 (depends on size of screw)

this means the propellor can bite more have more power at slower turn rate and its quieter cause it doesnt trun so much

badhat17 · 09-16-05, 09:23 PM

Take a look at this old thread.

http://www.subsim.com/phpBB/viewtopi...hlight=#244084

The important bit is the addition of the stator (static) blades , without those it would simply be a shrouded screw, they do look very similiar to a large turbofan primary compressor stage.

Deathblow · 09-16-05, 10:15 PM

So... I'm still not sure what the advantage is? What do the stators do that makes it better than just the rotator?

Kapitan · 09-17-05, 01:27 AM

the advantages are:

there quieter
more powerful
more econimic (uses less power in reactor)
turns slower
can make a ship go faster
unlike a propeller which can be damaged easily the propulsor has some protection

disadvantages:

kinda expencive to make
when one blade goes wrong they all do
refiting can be a night mare
inspecion crew dislike it cause they crawl into smaller spaces

Deathblow · 09-17-05, 12:25 PM

Oh, ok I get it....

.... Stators are magical..... just add stators and the propulsion is magically better.

Sounds like good engineering to me.

EDIT: ok, finally found a good link. I get it now. The pumpjet uses reduced outlet cross-section to ensure ejection flow speed is greater than inlet flow speed, as well as a propellar design, that are geared specifically to reduce the amount of radial and cicumferential flow leaving the blades, both which work to maximize the axial direction of the flow.

Kapitan · 09-17-05, 01:21 PM

good good

09-16-05, 06:01 PM	#1
Deathblow Captain Join Date: Sep 2005 Posts: 518 Downloads: 0 Uploads: 0	What exactly is a pumpjet propulsor? How is a "pumpjet propulsor" different than any other regular propellar? I see that its shrouded, but other than that what's the difference? Can anyone explain it to me? Did a google search and came up with nada.

09-16-05, 09:23 PM	#3
badhat17 Navy Dude Join Date: Jul 2002 Location: Derbyshire La La Laa Posts: 176 Downloads: 0 Uploads: 0	Take a look at this old thread. http://www.subsim.com/phpBB/viewtopi...hlight=#244084 The important bit is the addition of the stator (static) blades , without those it would simply be a shrouded screw, they do look very similiar to a large turbofan primary compressor stage. __________________

09-17-05, 01:27 AM	#5
Kapitan Sub Test Pilot Join Date: Mar 2005 Location: UK + Canada Posts: 7,130 Downloads: 77 Uploads: 7	the advantages are: there quieter more powerful more econimic (uses less power in reactor) turns slower can make a ship go faster unlike a propeller which can be damaged easily the propulsor has some protection disadvantages: kinda expencive to make when one blade goes wrong they all do refiting can be a night mare inspecion crew dislike it cause they crawl into smaller spaces __________________ DONT FORGET if you like a post to nominate it by using the blue diamond Find out about Museum Ships here: https://www.museumships.us/ Flickr for all my pictures: https://www.flickr.com/photos/131313936@N03/ Navy general board articles: https://www.navygeneralboard.com/author/aegis/

09-17-05, 01:21 PM	#7
Kapitan Sub Test Pilot Join Date: Mar 2005 Location: UK + Canada Posts: 7,130 Downloads: 77 Uploads: 7	good good __________________ DONT FORGET if you like a post to nominate it by using the blue diamond Find out about Museum Ships here: https://www.museumships.us/ Flickr for all my pictures: https://www.flickr.com/photos/131313936@N03/ Navy general board articles: https://www.navygeneralboard.com/author/aegis/

09-16-05, 06:04 PM	#2
Kapitan Sub Test Pilot Join Date: Mar 2005 Location: UK + Canada Posts: 7,130 Downloads: 77 Uploads: 7	you ever looked inside a jet engine ? if not it has tiny thin fan blades so instead of 5 or 7 blades you might have 70 or 80 (depends on size of screw) this means the propellor can bite more have more power at slower turn rate and its quieter cause it doesnt trun so much __________________ DONT FORGET if you like a post to nominate it by using the blue diamond Find out about Museum Ships here: https://www.museumships.us/ Flickr for all my pictures: https://www.flickr.com/photos/131313936@N03/ Navy general board articles: https://www.navygeneralboard.com/author/aegis/

09-16-05, 10:15 PM	#4
Deathblow Captain Join Date: Sep 2005 Posts: 518 Downloads: 0 Uploads: 0	So... I'm still not sure what the advantage is? What do the stators do that makes it better than just the rotator?

09-17-05, 12:25 PM	#6
Deathblow Captain Join Date: Sep 2005 Posts: 518 Downloads: 0 Uploads: 0	Oh, ok I get it.... .... Stators are magical..... just add stators and the propulsion is magically better. Sounds like good engineering to me. EDIT: ok, finally found a good link. I get it now. The pumpjet uses reduced outlet cross-section to ensure ejection flow speed is greater than inlet flow speed, as well as a propellar design, that are geared specifically to reduce the amount of radial and cicumferential flow leaving the blades, both which work to maximize the axial direction of the flow.