In an effort to head-off any possible single-seat jet fighter developments by the Allies in World War 2 to compete with its vaunted Messerschmitt Me 262 "Schwalbe" single-seat, twin-engine jet fighter, German authorities were already on the lookout for a high-performance successor taking advantage of a thin, sharply-swept wing mainplane, advanced aerodynamics, and a twin-turbojet propulsion scheme. For Heinkel engineers in July 1944, this gave rise to the "P.1073" project - a form which would eventually influence the soon-to-be He 162 "Volksjager" design - the "People's Fighter" - detailed elsewhere on this site.
The P.1073 mimicked some of the form-and-function to be finalized in the He 162: the single-crew cockpit was seated at the extreme front-end of the well-contoured fuselage with excellent vision over the nose. The fuselage's shape tapered towards the rear to which a "V-style" tailplane arrangement was to be featured - negating the use of horizontal tailplanes altogether. The mainplanes, of slim chord, were well-swept towards the rear, noticeably lengthy, and positioned ahead of midships. These members were further mid-mounted along the sides of the fuselage.
The propulsion scheme was rather unique as World War 2 jet fighters went: one turbojet was to be fitted in an integrated housing over the fuselage at midships and a second unit would be positioned under the cockpit floor - this done to protect the pilot in the event of a bailout, improve pilot vision out-of-the-cockpit, and reduce the drag encountered with underslung wing engines (as in the Me 262). As a tricycle undercarriage was planned for ground-running, a nose leg would be set under the cockpit as well - this necessitated the underslung turbojet be fitted slightly offset to starboard for clearance of the nose leg (which itself would be slightly favoring the port side). The main legs would recess under each wing member.
Proposed power would come from 2 x Heinkel HeS 011 turbojet engines offering 3,305lb of thrust each. Because these engines had yet to reach serial production, 2 x Junkers Jumo 004 turbojets would be fitted for the interim, these offering a lower-rated output of 2,237lb of thrust.
As drawn up, the airframe carried a length of 33.9 feet, a wingspan of 39.2 feet, and a height of 11 feet. Empty weight was 9,722lb against an MTOW of 13,500lb. Estimated performance included a maximum speed of 630 miles-per-hour, a maximum operational range of 620 miles, and a service ceiling up to 46,000 feet )all assuming the HeS 011 turbojets being installed, otherwise figures were considerably reduced with the Junkers types).
There was an option for the aircraft to carry a pair of integrated underwing fuel tanks to help increase operational ranges.
For armament, the fighter was to sport a battery of 3 x 20mm MG151/20 automatic cannons in the nose, one mounted to port side and the remaining two to starboard. Alternately, the armament suite was also detailed as 2 x 30mm MK108 automatic cannons (all in the nose).
The original P.1073 design was the "P.1073.01.4" detailed above and a further evolution of the design became the "P.1073.01.8" which was projected as a high-altitude reconnaissance platform. An upswept wing of higher aspect ratio was planned in this offering. The third, and final notable, iteration of the design became "P.1073.02" which differed mainly in its use of a forward-swept wing mainplane arrangement. It is said that at least twenty offshoots of the P.1073 existed at some point.
In the end, none of these forms found favor with the RLM (German Air Ministry) but the P.1073 idea was pushed to become the He 162 in October of 1944. The aircraft had changed to become a single-engine design (dorsal-mounted turbojet) with a twin-rudder tail unit and unswept wing mainplanes - the aircraft made as simple to operate and maintain as possible due to the losing German war effort heading into 1945. Three-hundred twenty (320) examples were eventually completed of this compact fighter with a first-flight undertaken on December 6th of 1944. Service introduction began as soon as January of 1945 but the design held little sway in the ultimate outcome of the war - in May of 1945, Germany was defeated.
Has the P.1073 project, in its original form, been pursued beyond the concept stage, there no doubt would have arisen issues regarding its unorthodox arrangement - which would have been noticed by RLM authorities - sure to cause Center-of-Gravity (CoG) issues during testing. There was also the danger of a pilot ejection just ahead of the dorsal intake opening - which would have presented problems all its own, particularly at high speeds.