MANUFACTURER(S): Dornier Flugzeugwerke - Nazi Germany
LENGTH: 44.62 feet (13.6 meters)
WIDTH: 50.69 feet (15.45 meters)
HEIGHT: 18.04 feet (5.5 meters)
WEIGHT (EMPTY): 15,124 pounds (6,860 kilograms)
WEIGHT (MTOW): 24,912 pounds (11,300 kilograms)
ENGINE: 2 x Heinkel-Hirth HeS 011 turbojet engines developing 2,860 lb of thrust each.
SPEED (MAX): 548 miles-per-hour (882 kilometers-per-hour; 476 knots)
RANGE: 870 miles (1,400 kilometers; 756 nautical miles)
CEILING: 29,593 feet (9,020 meters; 5.60 miles)
RATE-OF-CLIMB: 2,205 feet-per-minute (672 meters-per-minute)
Detailing the development and operational history of the Dornier Do P.256 (Project 256) Night-Fighter / Fighter-Bomber Aircraft Proposal.
Entry last updated on 1/6/2017.
Authored by Staff Writer. Content ©www.MilitaryFactory.com.
Dornier of World War 2 Germany was forced by the Air Ministry to focus its production strength on bomber types, namely its important Do 17 and Do 217 lines as well as several flying boat types. However, this did not stop the company from attempting to sell the Luftwaffe on a few fighter designs of which the most important became the Do 335 "Arrow". This aircraft became one of the more unique of the war, a heavy fighter with a twin-engine (propeller-driven) arrangement in which the nose held one of the powerplants and the tail fitted the other. The fighter had the potential to be one of the war's best based on its presented speed and firepower but production issues limited output to just 37 examples by war's end in 1945.
Another late-war fighter design attempt by the company became "Project 256" - or "P.256". This was centered around a February 1945 RLM requirement for a twin-engined, jet-powered all-weather/night fighter intended to remedy the situation in the air war and wrestle superiority away from the enemy before ground forces could swoop in an claim vital German facilities and force an end to the war. The P.256 could be broadly considered a jet-powered form of the prop-driven Do 335 for it used various elements first encountered with that design though, by and large, it was its own unique fighter offering.
Since the turbojet pairing would be contained in underwing nacelles, the nose was clear to bring the cockpit forward and provide for better pilot vision. The empennage was made up of a conventional tail unit showcasing a large-area vertical fin as well as low-set horizontal planes. The low-wing mainplanes were left unswept - though there was some sweepback of the leading edges. The members were fitted at midships and each held an underslung engine pod along their midway point. A tricycle undercarriage rounded out the design's key physical qualities - a feature seen in the Do 335. The engine of choice became 2 x Heinkel-Hirth HeS 011 turbojets outputting 2,865 pounds of thrust each.
Internally, it was thought that the aircraft would be crewed by three due to the systems required for the night-fighting role. Hence there would be a pilot, navigator and radar operator positioned in a pressurized cabin. The pilot shared the cockpit with the radar operator in a side-by-side seating arrangement while the navigator was set further aft in his own workspace facing aft. Survivability was enhanced some by way of cockpit armoring and bullet-resistant glass panels. Aft sections would be left largely unprotected and no defensive armament fitted - the thought being that the jet could simply out-fly any trailing interceptors at will.
As a "night stalker", the P.256 was proposed with 4 x MK 108 cannons in its nose assembly and a further 2 x MK 108 cannons fitted within the fuselage. The latter pairing would be angled in such a way as to be able to engage enemy bombers from their more vulnerable undersides - this known in the German inventory as the "Schrage Musik" oblique mount. A radar installation would allow the aircraft to be directed to incoming bomber formations in the dark of night, the P.256 holding all of the advantage against a target which lacked much in the way of detection facilities. Despite its primary role of night-fighter, the P.256 was also fashioned with two underwing hardpoints for carrying up to 2,200 pounds of conventional drop stores. In this way, it could double as a fighter-bomber in daylight hours.
All told, the design was given an overall length of 44.6 feet, a wingspan of 50.8 feet and a height of 18 feet. Estimated performance specifications were an absolute maximum speed of 550 miles per hour with ranges out to 875 miles. A service ceiling of 29,600 feet necessitated onboard oxygen supplies and cabin pressurization for the crew. Rate-of-climb was to be a useful 2,200 feet per minute.
After review, the P.256 submission was found wanting for it lacked key sought-after qualities found in competing designs. The unswept wing mainplanes were a detriment to speed and high-performance envelopes where jet fighters were concerned and the podded engine arrangement served only to add drag and further reduce performance (as proven in the Me 262).The large-area tail fin was another drag-inducing feature that added to the project's woes.
Since the P.256 submission held little to recommend itself, it was discarded from contention, forcing Dornier back to its production of bombers for the Luftwaffe. As such, the design became nothing more than another abandoned German jet project of the war and progressed little beyond its paper form.
Such was the fate of many late-war jet-powered platforms.
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Relative Maximum Speed Rating
This entry's maximum listed speed (548mph).
Graph average of 562.5 miles-per-hour.
Graph showcases the Dornier Do P.256's operational range (on internal fuel) when compared to distances between major cities.
Useful in showcasing the era cross-over of particular aircraft/aerospace designs.
Unit Production Comparison
Comm. Market HI*: 44,000 units
Military Market HI**: 36,183 units