Editing Dornier Do 335 (section)

==Design and development==
The origin of the Do 335 goes back to [[World War I]] when [[Claude Dornier]] designed a number of [[flying boat]]s with tandem engines. These were used on most of the multi-engined Dornier flying boats that followed, including the highly successful [[Dornier Do J|Do J]] ''Wal'' and the gigantic [[Dornier Do X|Do X]].
The main advantage of this arrangement is the reduced drag due to the smaller frontal area. It also keeps the weight of the twin powerplants near, or on, the aircraft centerline, increasing the [[Yaw, pitch, and roll|roll rate]] compared to a traditional twin. In addition, a single engine failure does not lead to [[asymmetric thrust]], and in normal flight there is no net torque, so the aircraft is easier to handle. The ventral  [[Vertical stabilizer|fin]]–[[rudder]] of the [[cruciform tail]] protected the rear propeller from  accidentally striking on takeoff. The presence of the rear pusher propeller also necessitated the provision for an [[ejection seat]] for safe escape from a damaged aircraft, and designing the rear propeller and dorsal fin mounts to use explosive bolts to jettison them before an ejection was attempted – as well as twin canopy jettison levers, one per side<ref>{{Cite web |url=http://www.century-of-flight.net/Aviation%20history/photo_albums/images13/16.jpg |title=NASM's restored Do 335A's cockpit, displaying the starboard-side example of the twin canopy jettison levers |access-date=2014-03-25 |archive-date=2015-09-23 |archive-url=https://web.archive.org/web/20150923202043/http://www.century-of-flight.net/Aviation%20history/photo_albums/images13/16.jpg |url-status=dead }}</ref> located to either side of the forward cockpit interior just below the sills of the five-panel windscreen's sides, to jettison the canopy from atop the cockpit before ejection.<ref>{{cite web |url=http://www.century-of-flight.net/Aviation%20history/photo_albums/timeline/ww2/Dornier%20Do%20335%20Pfeil.htm |title=Century of Flight - German Aircraft of World War Two - Dornier Do 335 Pfeil |author=<!--Staff writer(s); no by-line.--> |website=www.century-of-flight.net |publisher=Century of Flight |access-date=2014-03-25 |archive-date=2007-11-11 |archive-url=https://web.archive.org/web/20071111141212/http://www.century-of-flight.net/Aviation%20history/photo_albums/timeline/ww2/Dornier%20Do%20335%20Pfeil.htm |url-status=dead }}</ref>

In 1939, Dornier, reviving a principle he had patented in 1937,{{Sfn | Munson | 1978 | p =  47}} was  working on the '''P.59''' high-speed bomber project, which used the tandem engine layout. In 1940, he commissioned a test aircraft, closely modeled on the airframe of the early versions of the [[Dornier Do 17]] bomber but only 40% of the size, with no aerodynamic bodies of any sort on the wing panels (the Do 17 had twin engine nacelles on its wings) and fitted with a retractable [[tricycle landing gear]] to validate his concept for turning the rear [[Pusher configuration|pusher]] propeller with an engine located far away from it, through the use of a long tubular driveshaft. This aircraft, the [[Göppingen Gö 9]],{{sfn|Creek|Smith|2018|p=46}} showed no unforeseen difficulties with this arrangement, but work on the P.59 was stopped in early 1940 when [[Hermann Göring]]{{Citation needed|date=February 2008}} ordered the cancellation of all projects that would not be completed within a year or so.

In May 1942, Dornier submitted an updated version with a {{cvt|1000|kg}} bomb load as the '''P.231''', in response to a requirement for a single seat, ''[[Schnellbomber]]''-like high-speed bomber/intruder. The P.231 proposal was selected as the winner after beating rival designs from [[Arado Flugzeugwerke|Arado]], [[Junkers]], and [[Blohm & Voss BV 155|Blohm & Voss]]. A development contract was awarded, by the RLM issuing the Dornier firm the airframe approval number [[List of RLM aircraft designations#301-400|''8-335'']], for what would become known as the Do 335. In autumn 1942, Dornier was told that the Do 335 was no longer required, and instead a multi-role [[Fighter aircraft|fighter]] based on the same general layout would be accepted. This delayed the prototype delivery as it was modified for the new role.

[[File:Dornier Do 335 (1944), prototype (Dia 240-226).jpg|thumb|left|A Do 335 prototype in flight]]
[[File:Oberpfaffenhofen Do-335s.jpg|thumb|Do-335s on the apron at [[Oberpfaffenhofen]] at the war's end, including unfinished two-seat versions]]

When fitted with [[Daimler-Benz DB 603|DB 603A]] engines delivering {{cvt|1,750|PS|kW hp}} it had a pair of the largest inverted V12 aircraft engines mass-produced during the Third Reich's existence. The Do 335 V1 first prototype '''CP+UA''', flew on 26 October 1943 under the control of ''[[Flugkapitän]]'' [[Hans Dieterle]], a regular [[Heinkel]] test pilot and later primary Dornier test pilot. However, several problems during the initial flight of the Do 335 would continue to plague the aircraft through most of its short history. Issues were found with the weak [[landing gear]] and with the main gear's wheel well doors, resulting in them being removed for the remainder of the V1's test flights. The Do 335 V1 made 27 flights, flown by three different pilots. During these test flights the second prototype, V2 (''Werk Nr'' 230002) CP+UB, was completed and made its first flight on 31 December 1943, again under the control of Dieterle. New to the V2 were upgraded DB 603A-2 engines, and several refinements learned from the test flights of the V1 as well as further windtunnel testing. On 20 January 1944, the Do 335 V3 (''W.Nr.'' 230004), CP+UC was completed and flown for its first time by Werner Altrogge. The V3 was powered by the new pre-production DB 603G-0 engines which could produce {{convert|1900|PS|kW|abbr=on}} at take-off and featured a slightly redesigned canopy which included twin rear-view mirrors in blisters, one in each of two matching side panels of the well-framed, eleven-panel main canopy's openable section. Following the flights of the V3, in mid January 1944, RLM ordered five more prototypes (V21–V25), to be built as night fighters. By this time, more than 60 hours of flight time had been put on the Do 335 and reports showed it to be a good handling, but more importantly, very fast aircraft, described by ''[[Generalfeldmarschall]]'' [[Erhard Milch]] himself as "...holding its own in speed and altitude with the [[Lockheed P-38 Lightning|P-38]] and it does not suffer from engine reliability issues". The Do 335 was scheduled to begin mass construction, with the initial order of 120 preproduction aircraft to be manufactured by ''Dornier-Werke [[Friedrichshafen]]'' (DWF) to be completed no later than March 1946. This number included a number of bombers, destroyers (heavy fighters), and several yet to be developed variants. At the same time,  ''Dornier-Werke [[München]]'' (DWM) was scheduled to build over 2,000 Do 335s in various models, due for delivery in March 1946 as well.

[[File:Dornier Do 335 (1944), prototype (Dia 240-225).jpg|thumb|right|One of the prototypes under tow, date unknown]]
On 23 May 1944, [[Adolf Hitler|Hitler]], as part of the developing ''[[Emergency Fighter Program|Jägernotprogramm]]'' (Emergency Fighter Program) directive, which took effect on 3 July, ordered maximum priority to be given to Do 335 production. The main production line was intended to be at [[Manzell]], but a bombing raid in March destroyed the tooling and forced Dornier to set up a new line at [[Oberpfaffenhofen]]. The decision was made, along with the rapid shut-down of many other military aircraft development programs, to cancel the [[Heinkel He 219]] [[night fighter]], which also used the DB 603 engines (in well-[[Kraftei|unitized installations]]), and use its production facilities for the Do 335 as well. However, [[Ernst Heinkel]] managed to delay, and eventually ignore, its implementation, continuing to produce examples of the He 219A.

At least 16 prototype Do 335s were known to have flown (V1–V12, W.Nr 230001-230012 and ''Muster''-series prototypes M13–M17, W.Nr 230013–230017) on a number of DB603 engine subtypes including the DB 603A, A-2, G-0, E and E-1. The first preproduction Do 335 (A-0s) starting with W.Nr 240101, ''Stammkennzeichen'' VG+PG, were delivered in July 1944. Approximately 22 preproduction aircraft were thought to have been completed and flown before the end of the war, including approximately 11 A-0s converted to A-11s for training purposes. One such aircraft was transferred to the [[Royal Aircraft Establishment]] at [[Farnborough Airport|Farnborough]], and later, after a rear-engine fire burnt through the elevator controls during a flight, crashed onto a local school.<ref>{{cite web|last1=Smith|first1=Joshua|title=Farnborough Air Sciences Trust Museum uncovers secrets behind a plane which crashed on Cove school |url=http://www.gethampshire.co.uk/news/local-news/farnborough-air-sciences-trust-museum-10804711|website=GetHampshire |publisher=Aldershot News & Mail Series |access-date=1 February 2016 |ref=Smith |url-status=dead |archive-url=https://web.archive.org/web/20160201094738/http://www.gethampshire.co.uk/news/local-news/farnborough-air-sciences-trust-museum-10804711|archive-date=1 February 2016}}</ref>