The Germans bomb the US a workable scenario

Why would you need aircraft as tankers if you send a U-boat that is a tanker? The only limitation on seaplanes is weather. They land, taxi up to the U-boat, and refuel from it. With the BV 222 it's even easier as the plane's engines are diesel so you can use the same fuel the U-boat uses. You would need a Type XIV tanker U-boat for 6 BV 222 as the required fuel for two refuelings is on the order of 120 to 150 tons of fuel total.

 

I-15, I-19, and I-26 were converted into Avgas tankers to support the H8K 2nd attack on Pearl Harbor mission. The E14Y Glen was removed from the hangar, and 6 Avgas tanks with associated plumbing and pumps were added. After the mission was over, the submarines were converted back.

 

'Doumo'

 

Well, mostly because that is the type suggested for the mission. And partly because German land planes of the time simply didn't have the appropriate range and carrying capacity for the mission to work. Thd nearest I can think of off the top of my head is the Condor, but those were in short supply, desperately needed for more important things, and notoriously fragile when overloaded

 

It is a lot more risky.

1) can they find each other? Admittedly easier to spot the sub from an aircraft, but if you're using radio the Allies will know where you are, and if you're not then you might miss...

2) Germany had trouble predicting Atlantic weather, because it flows West to East. Missions would effectively be a gamble on weather conditions mid-Atlantic

3) what if the sub gets sunk?


All these problems are resolved if your spare fuel is flying alongside you for the whole journey

 

Norway to Chicago or Detroit is about 3000 nautical miles, about the one-way range of aircraft like the BV-222, Ju-290, or HE-177. To do it entirely by air would be something like the RAF's Black Buck missions in the Falklands war, in which getting one bomber to target required eleven tankers and seventeen aerial refuelings, most of them tanker-to-tanker. The tankers themselves burned the majority of fuel expended in the operation.

In that case, tankers did not accompany the bomber the whole way; the homebound bomber had to rendezvous with a tanker from a second wave.

Aerial refueling for long-range missions often involves pre-positioned assets. For example, when we flew B-2s from the States to attack Afghanistan, they refueled near Hawaii, Guam, and Diego Garcia from tankers that took off as the bombers approached. Obviously modern communications and navigation were important. We might also note that refuelings took place where ground control radar was available.

Weather forecasting might be an argument in favor of having a pre-positioned asset, ship or U-boat, which could confirm the weather situation before the final go order (whether or not it was involved in refueling).

 

One other benefit to TA's U-boat and BV-222 scenario, the sub could carry the mission crews. The planes could be flown to the rendezvous by a separate crew, so the mission crew would be fresh. This would apply mainly to the pilots and other flight crew; gunners might not need to be changed - or even carried on the first leg if the U-boat had room for them. The ferry crews could rest on the sub during the mission and then take the planes back.

 

Yes, they can find each other. The Germans ran an air mail and limited passenger service to S. America using a mid-ocean stop at a tender.



They used navigation aids like the Lorenz system to help the planes find the tender. The same could be done here where the U-boat turns on a homing beacon that is directional enough to be hard to detect by the enemy unless they were specifically looking for it while the planes know what to look for and about where to look to begin with.

The Germans in 1942 had weather stations on Greenland, and the sub(s) could show up days ahead of the mission to check the weather. They would have reasonable, for 1942, weather reports and the mission would be flown in mid to late summer when the weather is the best. This also means at the latitudes the planes and subs are at that it's daylight like 16 hours a day or more meaning they are operating in daylight for the most part.
For the bombing run into the US, the seaplanes take off timed to arrive on target as night falls or at night (the cities would be full lit up no blackout) then fly back towards the sub such that they arrive after sunrise to make landing and refueling easier.

What if one of the planes crashes? What if one or more breakdown? What if... These are problems and issues which could plague any mission of this sort.

 

Again this would work well the first time...but after that the allies would be ready...Ready at the coast of the US and using calculations patrol the areas that MUST be the refuelling point/s...You would see the Short Sunderland patrolling the area - even with radar. The Sunderland is an aircraft that doesn't get the credit it deserved, VERY capable anti sea aircraft - A rival for the PBY Cats...

The Americans would form their own wolf packs looking for these refuelers - And they would find them.

 

Most of us would probably agree that this would likely be a one-shot or rarely-repeated operation. Much of its value might be the diversion of American resources to air defense, something we did not have to worry about in the homeland historically.

 

I did not know about the South America route, that's amazing. The crazy things that were done back in the 20s and 30s when flight was still evolving

 

I could see a one-shot or two-shot raid carried out this way and that would be enough for the US to definitely up their defense game. That's particularly true if carried out in 1942. The US and UK don't have the ASW assets in place to hunt down a one-off raid yet, and the war is not clearly going in the Allies favor. I could see a panic in the US over even a small raid.

Imagine Chicago go hit by a dozen scattered 500lbs bombs. Or, a major car factory in the Detroit region gets hit by a couple of bombs... There would be a panic in 1942.

 

Hands down, the best ASW patrol plane of WW 2 was the B-24 / PB4Y. A Sunderland doesn't have the range to operate off Greenland. The B-24 does. But in 1942 the USAAF had a premium on those and it took Congressional and Presidential intervention to give the US Navy 300 planes for ASW use.

 

You know what we’ve done?
Come up with an awesome ‘what if’ movie.
Hitler orders an attack on the United States…Using the funds from a recent gold hoard find - Half a billion Deutsche Marks…two camps, one an air attack, one a submarine attack on the Continental United States…The love interest can come when a CIA agent infiltrates the Nazi hierarchy - A Nazi agent infiltrates the White House - Both have partners as cover…Their partners find out their identity and are torn whether to tell anyone…The agents torn whether they should liquidate their partners…
With Amerika bombers and purpose built U-Boats - P-47 interceptors (and whatever the Americans rush into service) This would be an awesome what if - What if the DID try it? It’s talked about, even today : )