Even as early as 1938, Nazi Germany made plans for an eventual war against the United States. It was understood that the U.S. would come to the aid of its allies in Europe so, to force American attention on its own defense (and thus take resources away from allies in France and Britain), the United States would become a direct target of German bombers. The major problem for the Luftwaffe at this time was its lack of long-range heavy bombers capable of carrying out such a monumental journey with a full war load. Thus the foundation was set for the "Amerika Bomber" program requiring a bomb delivery platform capable of crossing the Atlantic and making the return home - an inherent range of 3,600 miles was the listed project goal. Targets of particular interest were along the American East Coast - New York, Washington, D.C., Boston, etc...
Ultimately there proved many takers in support of the program - Horten, Messerschmitt, Focke-Wulf, Heinkel, Junkers all threw their hats into the ring in one way or another - but the project did not gain official steam until early-1942 when the United States officially committed to the war effort. For its part, Messerschmitt developed the "Me P.08-01", a large, multirole "flying wing" which emerged from design work in 1941. It was thought that the massive aircraft would be worth the investment if it went beyond its expected heavy bomber role - serving the Luftwaffe as heavy-lift transport, an airspace denial platform, long range reconnaissance / maritime patrol system, and possibly "mothership" for towed glider-fighters.
The design utilized an all-wing approach, lacking any true, defined tail unit save for a sole vertical fin. The cockpit was seated at the apex of the "arrow" type shape and the wing planform had swept-back leading edges with a partially swept-back trailing edge design (the area near center mass was straight-edged). All of the crew sections were concentrated in the center mass of the aircraft with a hold separating the flight deck and rear quarters. The hold provided enough internal space to carry a combat tank, this loaded into the aircraft by war of a rear-facing ramp. A tricycle undercarriage was therefore a requirement of the design, adding enough ground clearance for the spinning propeller blades as well as enough overhead clearance for cargo to clear the belly of the aircraft when loading / unloading. It is assumed that there would have been various defensive armament positions in the form of cannon-armed turrets - either in the nose or tail of the aircraft (or both) - though nothing was defined regarding this.
Four engines would be required to get the aircraft aloft and maintain a viable cruising speed - this propulsion power fell to 4 x Daimler-Benz DB9-615 piston engines seated within the blended body-wing of the aircraft. Furthermore, the engines were arranged in a "pusher" configuration - that is, the propellers being driven aft of the engine as opposed to ahead of it ("puller") - with air brought in through rectangular intake slots at the wing leading edges. Estimated speeds reached 400 miles per hour and range varied based on battlefield role.
Proposed dimensions for the P.08-01 included a wingspan of 50.6 meters, a length of 15.35 meters, and a height of 8.6meters. Its crew would number four. Loaded weight reached an estimated 90,000 kilograms.
The design direction of a flying wing added many inherent benefits for such an aircraft. Lift was generated naturally by the large wing area and this also affected rate-of-climb positively. At the expense of drag, the body-wing blending gave much internal volume for cargo, fuel (extending operational ranges), and other internal components and spaces. For the intended bombing role, the internal bay could carry upwards of 20,000 kilograms of conventional drop stores. Listed ranges between the tactical and strategic bombers varied due to the fuel stores set to be carried - 2,500 km against 15,000 km respectively. For the airspace denial role, the aircraft could fit 4 x 88mm FlaK Anti-Aircraft (AA) guns and, as a dedicated heavy-lift transport, the P.08-01's hold could manage an impressive 25 tons of war goods. The tactical reconnaissance version would outdo them all in terms of range - flying out to distances measuring some 27,000 kilometers.
The Me P.08-01, like many of the other proposed Amerika Bombers, resulted in a design study and nothing more. It was eventually found that many of these initiatives proved overly complex and expensive under the stresses of wartime and detrimental to the German war effort faced with dwindling strategic resources and materials. In fact, a 1943 German Air Ministry (RLM) directive forbade the investment in heavy bombers as the Luftwaffe was now facing a more defensive-minded war in the skies against Allied bombers - this led to a plethora of emergency fighters and interceptors being developed by war's end. Few of these ever saw the light of day themselves.