no need to blow tanks?

[codmander]

how come we dont have to blow tanks when surfacing ? at least no compressed air gets used unless you blow em under emergancy than you pop like a ballon to the surface,,, down 200 meters or so the tanks are filled with water and should have to be blown to rise thoughts?:hmm:

[GoldenRivet]

yeah... what he said... and how come no compressed air is used when a torpedo is fired? are torpedoes not pushed out of the tubes by a blast of compressed air?

:hmm:

i think we have been had!!

I wonder if there is a way to mod the surface command and the fire torpedo commands to use up a small bit of compressed air??? or to simulate various components using compressed air - the compressed air will gradually leak down ever so slightly over the course of several hours

[deepboat]

especially when the loo is used!

[BulSoldier]

I think the developers thought of a submarine like a plane.Only the wings (dive planes) control the dive or surfacing.While ballast tanks can be blown for a fast surface.Interesting i never thought of that hole in the game :)

[froschman]

But I do loose compressed air! During patrol I do dive to about 20 m for listening on the hydrophone. When I surface afterwards I lose some compressed air, and it takes half an hour to reload. When reloaded the crew reports it.

I am running GWX 2.0.

[Brag]

At low speeds or with engines stopped, when you surface you will notice that compressed air been somewhat depleted. Try diving and surfacing in quick succession and you will notice considerable compressed air usage.

[looney]

Yups same here.. when at slow speed it uses more air. Try surfacing from 200m at 0knots

[von Zelda]

how come we dont have to blow tanks when surfacing ? at least no compressed air gets used unless you blow em under emergancy than you pop like a ballon to the surface,,, down 200 meters or so the tanks are filled with water and should have to be blown to rise thoughts?

Compressed air was normally NOT used to surface a boat! Propulsion and hydroplanes were used to bring the boat to nearly surfaced and exhaust fumes from the diesel engines removed all remaining water from the diving tanks.

From chapter 4, page 51 of U-boat Commanders and Crews 1935 - 1945 by Jac P Mallmann Showell (isbn 1861261926)

"Many science books suggest that air was blown into the diving tanks to bring a submerged submarine to the surface, which is not quite correct. Diving tanks need to be open to the sea, and water pressure decreases as the boat rises. Therefore, the volumn of air in the diving tanks expands as the boat rises, which will produce an uncontrollable upward motion.

To prevent the boat from coming to the surface in a mass of bubbles like a champagne cork released under water, a careful surfacing procedure had to be maintained, and this usually did NOT involve the pumping of air into the diving tanks. In fact the oposite usually happens: water is pumped out of the tanks as the boat rises to allow for the expanding hull.

Before surfacing it was necessary to determine whether it was safe to do so.......... The next step was to engage the hydroplanes to steer the boat to periscope depth, and then to the surface. The trim would have allowed the upper deck of the casing to come roughly level with the surface of the water, but the boat would have been too heavy to get much higher. At this stage the conning tower, with the ends of the ventilation shafts on the top, was clear of the sea, making it possible to start the diesel engines and to use the exhaust fumes for blowing water out of the diving tanks. This had the advantage of saving compressed air."

[Penelope_Grey]

Usually I always surface with one press of the E key.. its quicker.

[von Zelda]

Usually I always surface with one press of the E key.. its quicker.

You are surfacing like a cork. Besides, BdU requires you to stop at periscope depth and check the surface and sky for contacts before surfacing. Suggest you read your U-boat Commanders Handbook. Otherwise, they may send you to the Eastern Front.<g>

[Sailor Steve]

...down 200 meters or so the tanks are filled with water and should have to be blown to rise thoughts?:hmm:
When you perform a crash (emergency) dive the tanks are full, and must be partially blown to achieve neutral bouyancy. In a normal dive, and when operating submerged, the tanks are only half (or so) full. Rising and sinking are controlled with the dive planes; this includes surfacing. Either when surfacing or shortly after the tanks are emptied, giving positive bouyancy. If done just before surfacing, this does require compressed air. If done after breaking surface, engine-powered blowers are used.
http://www.maritime.org/fleetsub/chap18.htm#18C

When the torpedoes are fired, some compressed air is used, but compensating for the lost weight of the torpedoes requires taking on water, not expelling it. Here is the straight dope:
http://www.maritime.org/fleetsub/chap19.htm#19A

[Jimbuna]

Usually I always surface with one press of the E key.. its quicker.

I thought that was the emergency eject button http://imgcash6.imageshack.us/img231/1076/shockedvi8.gif http://imgcash1.imageshack.us/img144/9897/bangheadgb1.gif

http://imgcash3.imageshack.us/img412/4774/thumbsuplargeon1.gif

[codmander]

hmm intresting I would think tho... for realizm that a touch more air would be used from compressed air when sumerged to the extreme.. if more is used at slower speeds It must be adjustable somewhere in game file maybe the modders could toy with it :hmm: I like the -s- key myself sounds are cooler with a little das boot in there as well

[von Zelda]

When you perform a crash (emergency) dive the tanks are full, and must be partially blown to achieve neutral bouyancy. In a normal dive, and when operating submerged, the tanks are only half (or so) full. Rising and sinking are controlled with the dive planes; this includes surfacing. Either when surfacing or shortly after the tanks are emptied, giving positive bouyancy. If done just before surfacing, this does require compressed air. If done after breaking surface, engine-powered blowers are used.
http://www.maritime.org/fleetsub/chap18.htm#18C

Sailor Steve, with all due respect, your article appears to be on US Fleet Submarine technolgy.

One must understand that German U-boat technology, contruction and engineering was some what different than US technology. According to Jac P. Malmann Showell (a noted U-boat and Kriegsmarine historian) under normal conditions U-boats did not inject compressed air into their diving tanks to surface but rather sea water was pumped out of the diving tanks to compensate for the expanding air within the diving tanks as the boat's depth was reduced by props and hydroplanes. Once the conning tower and diesel motor air intakes were above the surface, the diesels were started and their exhaust gases were first vented into the diving tanks to blow out all remaining sea water thus raising the boat to a normal surfaced depth.

One reason this might have differed from US subs is that many of the U-boat diving, fuel and ballast tanks were open to sea water and they had valves to allow for the release of air pressure within the tank and thus the flooding of the tank.

[Sailor Steve]

I don't see where we disagree; my point was that compressed air was not used or needed as much as some people seem to think. Your point seems to be the same, except with (possibly) slightly different technology and procedure.:sunny:

[von Zelda]

I don't see where we disagree; my point was that compressed air was not used or needed as much as some people seem to think. Your point seems to be the same, except with (possibly) slightly different technology and procedure.

I misunderstood your post, so we are in agreement. Thanks.

[Subnuts]

yeah... what he said... and how come no compressed air is used when a torpedo is fired? are torpedoes not pushed out of the tubes by a blast of compressed air? :hmm:


Simple answer: The torpedoes were fired using a different compressed air system than the one that blew the ballast tanks. Maybe. :doh:

[von Zelda]

yeah... what he said... and how come no compressed air is used when a torpedo is fired? are torpedoes not pushed out of the tubes by a blast of compressed air?
Simple answer: The torpedoes were fired using a different compressed air system than the one that blew the ballast tanks. Maybe.

IIRC, there were compressed air tanks located in the forward torpedo room. A large diaphram with the same dimensions as the tube was placed behind the torpedo after it was loaded into the torpedo tube. It was the compressed air pushing on the diaphram which resulted in the torpedo being pushed forward and out of the tube. The diaphram could only travel a certain distance within the tube before it came to a stop. The diaphram was removed from the tube and then another torpedo was loaded and process repeated.

[codmander]

look at the movie das boot gibralta dive to aviod aircraft emergancy blow ((not suppose to dive without cpt)) than a short steam south dive again stuck planes blow tanks than just enough for 1 more blast of course this is a movie and under emergancy so 3 emengancy blows is about it which is about right ingame :arrgh!: just the normal surfacing proceedures should be looked into as far as how much air was used --no biggie just some thoughts on this lovely day:rock:

[Rwolf]

How about the compressed air used for propelling the torpedos to target?
Would that air be pre-loaded in harbour, or something filled-up onboard?

[von Zelda]

l just the normal surfacing proceedures should be looked into as far as how much air was used


As discussed above in some length, no compressed air was used for normal surfacing.

[Sailor Steve]

Again, I can only refer to the US system. It looks like pumps could recharge the whole system anytime the sub was surfaced. I assum that u-boats could recharge the system using the schnorkel, as it also drew in air for the diesels and the crew's breathing air.
http://www.maritime.org/fleetsub/chap11.htm#11C

[von Zelda]

How about the compressed air used for propelling the torpedos to target?
Would that air be pre-loaded in harbour, or something filled-up onboard?

IIRC, no German topredo ran on compressed air. The G7e was electric and ran on batteries. The G7a was steam driven and ran on combustion of fuel.

As discussed above, compressed air was used to eject the torpedo from the tube.

[Jimbuna]

I have been feverishly looking through my reference books to no avail thus far, but IIRC there was a separate standalone compressed air reservoir for the expelation of German torpedoes :hmm:

[Sailor Steve]

Expelation?

"You keep using that word. I don't think it means what you think it means.":rotfl:

[Jimbuna]

Expelation?

"You keep using that word. I don't think it means what you think it means.":rotfl:

No, your right, the correct spelling is expilation...which is also the wrong word :damn:

Feck it!!...... I meant the firing of the torp out of the tube :oops:



http://imgcash3.imageshack.us/img412/4774/thumbsuplargeon1.gif

[Sailor Steve]

Maybe 'expelling'.:sunny:

I knew what you meant...I just have to keep running up the post count.:rotfl:

[von Zelda]

but IIRC there was a separate standalone compressed air reservoir for the expelation of German torpedoes

IIRC, there was a main air compression unit located in one of the engine rooms. I do recall seeing a diagram of a Type VII which showed compressed air canisters in the forward torpedo room. They would have needed an air compressor to recharge them and I don't think there was one in the forwrd torpedo room; so they may have been feed from the main compressor in the stern of the boat.

Also, I just read that there was compressed air in the G7a torpedo to help with the combustion. Maybe, the air canisters that I believe I saw on the diagram were used to charge up the G7a torpedos and the main compressed air system was used to launch torpedos.

However, we might be beating a dead horse by now. There are so many technical aspects in the boat that historians only slightly discribe, most they gloss over, in fact. So, we'll never know all the facts on the topics that we talk about.

[Rwolf]

How about the compressed air used for propelling the torpedos to target?
Would that air be pre-loaded in harbour, or something filled-up onboard?

IIRC, no German topredo ran on compressed air. The G7e was electric and ran on batteries. The G7a was steam driven and ran on combustion of fuel.

As discussed above, compressed air was used to eject the torpedo from the tube.

I searched some more info about this; Steam for torpedo propulsion is also produced by heating compressed air, so it's a possible use. Not sure if they needed topping off, or were only prefilled. It wouldn't be much air in any case I suspect.

wiki says 'compressed gas': http://en.wikipedia.org/wiki/G7a_torpedo

The japanese used compressed oxygene, with compressors generating it installed on the destroyers (based on german compressor tech), from what I understand in this link: http://inet.museum.kyoto-u.ac.jp/conference02/MorioNAKAHARA.html

[Kaleu. Jochen Mohr]

yeah... what he said... and how come no compressed air is used when a torpedo is fired? are torpedoes not pushed out of the tubes by a blast of compressed air? :hmm:

Simple answer: The torpedoes were fired using a different compressed air system than the one that blew the ballast tanks. Maybe. :doh:

bernard ? :hmm: human "gas" ? :hmm:

[NiclDoe]

:rotfl: :rotfl: @Mohr but his gas is deadly.

[Jimbuna]

yeah... what he said... and how come no compressed air is used when a torpedo is fired? are torpedoes not pushed out of the tubes by a blast of compressed air? :hmm:

Simple answer: The torpedoes were fired using a different compressed air system than the one that blew the ballast tanks. Maybe. :doh:

bernard ? :hmm: human "gas" ? :hmm:

Well don't anybody strike a match :p

http://img246.imageshack.us/img246/1336/htr3202ih7.jpg (http://imageshack.us)