Most frequently-used U-boot Class by you?

[Marcello]

Originally Posted by mafansiwo

Type XXI does not have a after torpedo tube,I dont like that.
If you have a destroyer surrounding you ,it is very difficult to fire a torpedo to the destroyer

The XXI was supposed to be equipped with a rear tube for Ursel supercavitating rocket (think Shkval with lower performances) for use as anti-destroyer weapon. As with many of the more fanciful projects in late war nazi germany it did not come to fruition and the space was used to fit a lathe and other machine tools for underway repairs. The B variant of the XXI was supposed to carry six rear firing torpedo tubes in addition to the forward ones, but this came at the expense of all internal reloads. The C would have carried 18 torpedo tubes (six forward, twelve angled aft) but in addition to internal realods battery capacity would have been reduced as well.

I think of tech that *almost* changed the face of WWII. The XXI, the V2, the ME262, the German jet-powered flying wing (can't recall the name), the Stg. 44, German nuclear weapons research...can you imagine if those were all front line equipment in '39?

The V2 was a technical marvel but essentially a waste of resources. The british were about on par with the germans on jet research, so whatever the germans did, they could more or less match. Main problem with subs in 1939 was not performance but lack of numbers: there were about sixty boats while prewar estimates calculated that about a thousands were needed to achieve decisive results. Since a XXI required much more scarce resources (copper, lead, rubber etc) than a VII or an IX that means fewer subs or fewer resources for something else. The XXI begins to be really attractive only once radar becomes a standard fit for ASW assets, which in 1939 was not yet the case IIRC.