Periscopes

Maverick30 · 04-26-08, 05:42 AM

In real life the kaleun used the periscopes at submerged high speeds (ex: 7knots above)? The periscope didn't suffered from high vibrations caused by hydrodynamic resistance?

JScones · 04-26-08, 05:47 AM

Periscopes were fitted with "helical rods" (or "helical wires") that broke the water flow into general turbulance so as not to create any resonating eddies in the water (more on what an eddy is here http://en.wikipedia.org/wiki/Eddy_%28fluid_dynamics%29).

Note that this did not fix the vibration of the scope tube itself, just the conical part. The vibration in the scope tube was removed by adding an extending bracket which increased the tube's natural resonant frequency.

Some examples:

Maverick30 · 04-26-08, 05:52 AM

Quote:

Originally Posted by JScones

Periscopes were fitted with "helical rods" (or "helical wires") that broke the water flow into general turbulance so as not to create any resonating eddies in the water (more on what an eddy is here http://en.wikipedia.org/wiki/Eddy_%28fluid_dynamics%29).

Note that this did not fix the vibration of the scope tube itself, just the conical part. The vibration in the scope tube was removed by adding an extending bracket which increased the tube's natural resonant frequency.

Some examples:

Thanks for replying, now I understand

Brag · 04-26-08, 08:02 AM

Excellent question and fantastic reply. One learns something new every day

geosub1978 · 04-26-08, 01:44 PM

In the type XXI submarines there was a switch which automatically lowered the masts including periscope at speeds > or = 9kts because the vibration was imposible to be removed. That switch could be ON / OFF / SURFACE MODE.

_Seth_ · 04-27-08, 06:16 AM

Quote:

Originally Posted by geosub1978

In the type XXI submarines there was a switch which automatically lowered the masts including periscope at speeds > or = 9kts because the vibration was imposible to be removed. That switch could be ON / OFF / SURFACE MODE.

True!

(IIRC, all schnorkel-equipped subs had "speed limits", so that the strain from the water would not break the equipment.)

04-26-08, 05:42 AM	#1
Maverick30 Watch Join Date: Jan 2007 Location: Portugal Posts: 27 Downloads: 18 Uploads: 0	Periscopes In real life the kaleun used the periscopes at submerged high speeds (ex: 7knots above)? The periscope didn't suffered from high vibrations caused by hydrodynamic resistance?

04-26-08, 08:02 AM	#4
Brag Navy Seal Join Date: Nov 2006 Location: Docked on a Russian pond Posts: 7,072 Downloads: 2 Uploads: 0	Excellent question and fantastic reply. One learns something new every day __________________ Espionage, adventure, suspense, are just a click away Click here to look inside Brag's book: Amazon.com: Kingmaker: Alexey Braguine: Books Order Kingmaker here: http://www.subsim.com/store.html For Tactics visit:http://www.freewebs.com/kielman/

04-26-08, 01:44 PM	#5
geosub1978 Samurai Navy Join Date: Oct 2006 Location: Salamis Base Posts: 567 Downloads: 229 Uploads: 0	Periscope Vibration In the type XXI submarines there was a switch which automatically lowered the masts including periscope at speeds > or = 9kts because the vibration was imposible to be removed. That switch could be ON / OFF / SURFACE MODE. __________________

04-26-08, 05:47 AM	#2
JScones Navy Seal Join Date: Apr 2005 Posts: 5,501 Downloads: 19 Uploads: 0	Periscopes were fitted with "helical rods" (or "helical wires") that broke the water flow into general turbulance so as not to create any resonating eddies in the water (more on what an eddy is here http://en.wikipedia.org/wiki/Eddy_%28fluid_dynamics%29). Note that this did not fix the vibration of the scope tube itself, just the conical part. The vibration in the scope tube was removed by adding an extending bracket which increased the tube's natural resonant frequency. Some examples: