What exactly is a pumpjet propulsor?

[Deathblow]

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]

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]

Take a look at this old thread.

http://www.subsim.com/phpBB/viewtopic.php?p=244084&highlight=#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]

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

[Kapitan]

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]

Oh, ok I get it....

.... Stators are magical..... just add stators and the propulsion is magically better. :88)

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]

good good