German WWII submarines with teardrop hulls

What impact would producing submarines with teardrop hulls but otherwise identical specifications to the Type VII and Type IX have if they entered service in 1940 or 1941? How noticeable would the difference in performance be, if any?
 
far worse performance when surfaced, where most U-Boats ran at.
Note the streamlining of the original Holland boat
uss-holland-no7-submarine.png

This was abandoned for better surface performance, since early boats rarely ran submerged for long periods of time
 
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Well, this would only make sense with combined use of Schnorkel technology. In many way, I think these to implementations go together. Originally the Germans were not to keen on the Dutch schnorkel boats. What is the point of a schnorkel with a design not made covering distances while submerged? When in combat mode, you would go on battery power anyway.
Teardrop shape+schnorkel, now things are happening and it could follow from the implementation of the schnorkel.
 
Well, this would only make sense with combined use of Schnorkel technology. In many way, I think these to implementations go together. Originally the Germans were not to keen on the Dutch schnorkel boats. What is the point of a schnorkel with a design not made covering distances while submerged? When in combat mode, you would go on battery power anyway.
Teardrop shape+schnorkel, now things are happening and it could follow from the implementation of the schnorkel.

Schnorchel Problems

There were several problems with the Schnorchels; first it turned the attacking/patrolling U-boat into a slow (6 knots was the max speed for the VII and IX types, otherwise the air mast would break off) and almost deaf weapon. Second were the various disposal problems associated with the permanently submerged boat; garbage had to be stored internally and further fouled up the boat. Third was the problem with the initial schnorchel masts that they tended to close up and thus the diesels, being starved of air from above, sucked all available air from the boat itself and causing extremely harmful ear pains and sometimes even damaged ear drums. http://uboat.net/technical/schnorchel.htm
 
True, the schnorkels at first were not Engineering marvels, but basically the kinks got sorted out in a few years.
Rationale behind was not magical either. Actually, strange that a field as novel submarine design would lose experimentation drive so fast after the Holland submarine.
 
The needs of World War I intervened to a large degree. But I am surprised not more was done between the wars.
 
The issue is do you have a vessel that is submerged the vast majority of the time, on on the surface most of the time and submerged only to hide or attack. Even modern diesel subs do not streamline the hulls the way nukes boats are streamlined. To the extent possible diesel boats run on the surface until they get close to where they are patrolling - of course subs in the Baltic, coastal subs in the North Sea/Norwegian Sea, and other locations where patrol areas basically start when you leave the pier (like Israeli subs in the Med) can be more streamlined as they will be submerged more or less like a nuke. For boats that have to go any distance which means on the surface, the Albacore style hull is not good.

Having deck guns or anti-aircraft mountings will negate a lot of the advantage of the Albacore hull. In WWII you needed both for a variety of reasons. Again, the problem is that even more modern subs are limited with how fast they can go with the snorkel up. If you need to transit a significant distance to get to your hunting grounds/patrol area, nuclear power, AIP, or some surface running is needed.
 
The conning tower and its various protrusions is responsible for 50+% of the underwater drag. Add to that the drag produced by the deck gun/s (I don't have that number on the top of my head), and the remainder is the hull form. Bottom line being that the hull form, while important, is not the biggest problem. A reasonable approximation is that battery drain is directly proportional to velocity x drag^3.

One could gain a significant amount of underwater performance simply by the conversion from "conning tower" to "sail" (like the GUPPY conversions); even without elimination of the deck gun. However, snorting significantly reduces speed so it really can't be used to maneuver into attack position; and that is critical for blue-water submarine operations in the Atlantic and Pacific.

During WWII, submerged attacks were a process of detecting a target, moving into attack position (on the surface outside escort detection range), submerge, try for an attack (hoping they don't zig when you want them to zag); rinse and repeat multiple times. Night surface attacks were popular for very good reasons. So, as several have pointed out, the albacore hull does not help in a blue-water approach/attack scenario.

A snorting submarine trades detection range on both sides of the equation (losing as much or more of its own detection range as it takes from the enemy). It's too noisy to use passive sonar plus both visual and radar ranges are significantly reduced. So, patrolling on the snorkel requires significantly more boats to cover any patrol area (or they patrol on the surface).

BTW, the Type XXI was really the forerunner to a revolution in ASW, not ASuW (as some believe) because battery capacity significantly limits the distance it can maneuver against a faster target. How long can that boat (or its more modern cousins) sprint on battery? Probably an hour at full or nearly full charge (which would completely drain the battery). So, while they could use their sprint to obtain favorable geometry during the attack phase, how much distance can they cover and much juice do they have left to operate? If a sprint of 8,000 to 10,000 yards can get you in position for the kill, advantage to the Type XXI (assuming he's got ~80+% charge to start), if not it's back on the surface to reposition. If the boat happens to be in the right spot, great; but outside choke points the "underwater speed advantage" falls precipitously. So relative to u-boats, the Type XXI is probably the best of both worlds for the era as a blue-water ship killer because it retains the surface range, has a "workable" surface speed (against the 10 knot convoys) and has much better ability to escape. An albacore hull would actually detract from that.
 
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The RN did experiment with the idea of a 'dissapearing' deck gun to reduce drag, but found it actually made little difference. But the idea could be implemented if desired
 
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