Technology and Operations
This forum is for discussing technological & operational matters pertaining to U-boats.
Re: Torpedo Launching
Posted by:
Ken Dunn
()
Date: October 29, 2003 12:21AM
Hi Robert,
I am not sure what hatch you are talking about but the Type VII did have a hatch between the control room and the conning tower. The one on U-352 is still shut and I have seen it. In combat with the rest of the watch queued up behind the commander to get to the bridge this hatch would have been open though. I think we may just be seeing the difference between peacetime procedures and wartime procedures. The boat was almost blind on the surface (with the exception of what could be seen through the periscope and the commander wasn't seeing anything if he was busy opening the hatch) without the watch on the bridge and every second counted. An aircraft bearing down on you can go a good distance in just a few seconds.
I think a more interesting question is how many torpedoes would have to be fired for the pressure released back in the boat to become enough to eject the first man out of the hatch. Gannon has the pressure of the compressed air necessary to launch a torpedo at "about 24 atmospheres". Given a 7 meter long torpedo of a known diameter the volume of the torpedo tube should not be too difficult for someone to estimate. However I don't know how to do the calculations to figure out how much each fired torpedo would raise the pressure inside the boat. It would be interesting if someone could crunch the numbers and determine if it was even possible for torpedo firing alone to raise the pressure that much. If it turns out that it can't then the extra pressure may have had to come from depth charge damage etc.
It is a fact that it happened and it would be interesting to know what actually caused it. There were 6 tubes on a Type IX and they could all be reloaded and fired again before surfacing.
Also cracking the hatch to bleed off the excess pressure only works if there isn't enough excess pressure to force the hatch the rest of the way open when it is just cracked (which might be the case here). I guess it all depends on how the hatch and its locking mechanism fits and works.
There is another thing too. U-boat commanders weren't normally large strong men. They usually didn't weigh that much although there were certainly exceptions to this. Perhaps their size and strength wasn't conducive to holding the hatch shut against the pressure. They may not have been able to get any leverage while opening the hatch either. After all at least one hand was required to open it and if two were required only their weight and a toe hold would be available to hold the hatch down so it didn't fly up. All just speculation but it did happen and there has to be a reasonable explanation for it. U-boat commanders weren't dummies either. On the contrary they were generally very bright and able to keep a calm head in an emergency. They also routinely practiced going through that hatch over and over again until it was second nature. There is something here we are missing.
Regards,
Ken Dunn
I am not sure what hatch you are talking about but the Type VII did have a hatch between the control room and the conning tower. The one on U-352 is still shut and I have seen it. In combat with the rest of the watch queued up behind the commander to get to the bridge this hatch would have been open though. I think we may just be seeing the difference between peacetime procedures and wartime procedures. The boat was almost blind on the surface (with the exception of what could be seen through the periscope and the commander wasn't seeing anything if he was busy opening the hatch) without the watch on the bridge and every second counted. An aircraft bearing down on you can go a good distance in just a few seconds.
I think a more interesting question is how many torpedoes would have to be fired for the pressure released back in the boat to become enough to eject the first man out of the hatch. Gannon has the pressure of the compressed air necessary to launch a torpedo at "about 24 atmospheres". Given a 7 meter long torpedo of a known diameter the volume of the torpedo tube should not be too difficult for someone to estimate. However I don't know how to do the calculations to figure out how much each fired torpedo would raise the pressure inside the boat. It would be interesting if someone could crunch the numbers and determine if it was even possible for torpedo firing alone to raise the pressure that much. If it turns out that it can't then the extra pressure may have had to come from depth charge damage etc.
It is a fact that it happened and it would be interesting to know what actually caused it. There were 6 tubes on a Type IX and they could all be reloaded and fired again before surfacing.
Also cracking the hatch to bleed off the excess pressure only works if there isn't enough excess pressure to force the hatch the rest of the way open when it is just cracked (which might be the case here). I guess it all depends on how the hatch and its locking mechanism fits and works.
There is another thing too. U-boat commanders weren't normally large strong men. They usually didn't weigh that much although there were certainly exceptions to this. Perhaps their size and strength wasn't conducive to holding the hatch shut against the pressure. They may not have been able to get any leverage while opening the hatch either. After all at least one hand was required to open it and if two were required only their weight and a toe hold would be available to hold the hatch down so it didn't fly up. All just speculation but it did happen and there has to be a reasonable explanation for it. U-boat commanders weren't dummies either. On the contrary they were generally very bright and able to keep a calm head in an emergency. They also routinely practiced going through that hatch over and over again until it was second nature. There is something here we are missing.
Regards,
Ken Dunn
