[Josh]

For torps that use peroxide or monofuel, or some other form of combustion, what do they do with the waste gases? Just vent out the back onto the prop? Does this depth limit them (water pressure greater than exhaust)? I assume that combustion engines are noiser, particularly piston driven designs like the Mk 48 with swash plate. I assume dumping gas off board also is going to make them more intrinsically noisy than electric torps. Also, how does a combustion engine supply electricity to the seeker? An alternator/magneto like an automobile/motor bike I assume?

And another question about launching torps...is it the case that combustion torps require ejection where as electric torps can 'swim out'? For torp ejection, a wiki article claims that using a high pressure slug of water has replaced compressed air...I've heard of this method but was unaware it was in wide spread use (wiki claims 'by everyone since the 50's' or something to that effect)?

[aevans]

In US Navy torpedoes in WWII, exhaust was vented through a valve system into the propeller hubs and out through holes in the propeller sleeves. The system contained pressure valves and an exhaust collection chamber so that exhaust pressure was allowed to build up until it ovecame outside sea water pressure. There was also a system to preven engine oil from getting in the exhaust and partially burning, so that the exhaust wouldn't contain smoke. Pretty nifty, huh?

I don't think the propulsion motor is involved in producing electrical power. AIUI, the instrument package has batteries.

WRT launching, yes, internal combustion torpedoes were ejected by some form of pressurized system, the motor being started by a mechanical switch being tripped on the way out. IC torpedoes are just too dangerous to allow their motors to run inside the vessel. Electrical torpedoes didn't have that problem and could be allowed to swim out to avoid making the classical launching noises. I think (though I am by no means sure) that one of the motivations for the water slug approach it to avoid the noise made by compressed air launches.

[hojutsuka]

aevans, on Tue 25 Aug 2009 2029, said:

I think (though I am by no means sure) that one of the motivations for the water slug approach it to avoid the noise made by compressed air launches.

Actually the water pulse system was adopted post-WW II to allow torpedoes to be launched at greater depths. During WW II, targets were all on the surface (with the exception of U-864 sunk while submerged by HMS Venturer 9 February 1945) so there was no need to fire torpedoes at great depths; the submarine firing the torpedoes would have to be near the surface to detect and track the target (periscopes were still the primary means of acquiring firing data). Post-WW II, ASW became an important part of submarine combat, which meant that torpedoes might have to be fired at the submarine's maximum diving depth. So modern submarines generally launch torpedoes using water pulse, swim out, or (in case of the French Navy) hydraulic rams, all of which can launch torpedoes at greater depths than the traditional compressed air.

Hojutsuka

[aevans]

hojutsuka, on Tue 25 Aug 2009 2127, said:

Actually the water pulse system was adopted post-WW II to allow torpedoes to be launched at greater depths.

Makes sense--water isn't as compressible as air, so sea water pressure at depth wouldn't collapse the working fluid and rob it of energy, is that right?

[Paul in Qatar]

Since the gas must equal the weight of the fuel and oxygen, the torpedo would get lighter and lighter throughout its run.

"I read somewhere," (so it must be true) that the exhaust gases were retained in order to keep the fish in balance. Anyone ever hear of something along these lines?

[Jason L]

Quote

Makes sense--water isn't as compressible as air, so sea water pressure at depth wouldn't collapse the working fluid and rob it of energy, is that right?

You'd need a lot of very high pressure gas to blow out around the flooded tube with enough velocity to force a torp out at significant depth, there is a large amount of Pdv work the gas would have to do to move both the torp and the water. I believe large reservoir, high pressure systems were capable at moderate depths (500 ft) but the gas handling starts to get prohibitive at later gen sub depths.

[Josh]

Its amazing how little one knows about submarine opperation until one asks. Truly the silent service. I had no idea compressed air wasn't used any more; even contemporary literature ('Red Storm Rising'--I know, hardly non fiction or a good source, but I thought they had at least done their home work) assumes that compressed air is used. They make note of the fact that at depth much more compressed air is needed...ironic if its not used at all. With regards to the French, why hydraulic rams? Is it the ever present need of the French to be different or is there a more practical reason?:)

[aevans]

Paul in Qatar, on Wed 26 Aug 2009 0202, said:

Since the gas must equal the weight of the fuel and oxygen, the torpedo would get lighter and lighter throughout its run.

"I read somewhere," (so it must be true) that the exhaust gases were retained in order to keep the fish in balance. Anyone ever hear of something along these lines?

Torpedoes were already designed to run at variable depth, without altering the weapon's buoyancy. The depth control mechanism took care of changes in buoyancy as a side effect of being able to control tactical running depth. Note that practice torpedoes were equipped with a buoyant recovery package in place ofthe warhead that guaranteed the weapon would float to the surface even if the motor never ran and no fuel was expended. These practice shots were routinely set to run deep enough to run under target vessels. The depth setting mechanism had no trouble exerting enough control authority to allow this.

As describe above, the exhaust gas was stored until it overcame outside water pressure on a set of relief valves, at which point it was vented to the outside environment until the pressure was equalized, then the valves closed and pressure started building up again. This cycle was repeated throughout the running life of the torpedo.

[ShotMagnet]

Quote

...practice torpedoes were equipped with a buoyant recovery package in place ofthe warhead that guaranteed the weapon would float to the surface even if the motor never ran and no fuel was expended.

Friend of mine, who was a pipe-fitter on a Russian boomer once upon a time, told me that the BRP for Soviet torpedoes is/was ethanol. Apparently quite a few practice rounds were lost because somehow the ethanol in the BRP of some rounds was replaced with water.


Shot

[Jason L]

Quote

Friend of mine, who was a pipe-fitter on a Russian boomer once upon a time, told me that the BRP for Soviet torpedoes is/was ethanol. Apparently quite a few practice rounds were lost because somehow the ethanol in the BRP of some rounds was replaced with water.

After a month in Russia I can give you a few ides as to how that happened :lol:

[Arminius]

and the MIG 25 was LOVED by ground crews, because it neede large amounts of alcohol for defreezing ...

;-)

Hermann

[aevans]

ShotMagnet, on Wed 26 Aug 2009 1523, said:

Friend of mine, who was a pipe-fitter on a Russian boomer once upon a time, told me that the BRP for Soviet torpedoes is/was ethanol. Apparently quite a few practice rounds were lost because somehow the ethanol in the BRP of some rounds was replaced with water.
Shot

US sailors had their torpedo juice, but they used the fuel. US exercise heads were balasted with water and blown out with compressed air at the end of the run.