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{{Short description|British bomber used during the First World War}}
{{Redirect|DH-4|the 1950s flying platform|de Lackner HZ-1 Aerocycle}}
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{{Use British English|date=November 2017}}
{{Infobox aircraft
| name = Airco DH.4
| image = De Havilland DH4 ExCC.jpg
| caption = A Canadian DH.4  registered G-CYDK parked.
| type = [[Light bomber]] / General purpose
| manufacturer = [[Airco]]
| builder = [[Boeing|Boeing Airplane Corporation]] <br/> [[Dayton-Wright Company]] <br/> [[Fisher Body]] <br/> [[Standard Aircraft Corporation]]
| first_flight = August 1916
| introduction = March 1917
| retired = 1932 (United States Army Air Service)
| status = Retired
| primary_user = [[Royal Flying Corps]]
| more_users = [[Royal Air Force]] <br/> [[Royal Naval Air Service]] <br/> [[United States Army Air Service]]
| produced = <!--years in production, e.g. 1970-1999, if still in active use but no longer built-->
| number_built = 6,295, of which 4,846 were built in the United States.<ref name=JacksonP58/><ref name=BruceP12>Bruce, 1966, p.12</ref>
| developed_into = [[Airco DH.9]] <br/> [[Airco DH.9A]] <br/> [[Dayton-Wright Cabin Cruiser]]
}}

The '''Airco DH.4''' is a British two-seat [[biplane]] [[day bomber]] of the [[World War I|First World War]]. It was designed by [[Geoffrey de Havilland]] (hence "DH") for [[Airco]], and was the first British two-seat light day-bomber capable of defending itself.

It was [[Bomber#The first bombers|designed and developed specifically as a bomber]], as well as [[aerial reconnaissance]] missions. The DH.4 was to have been powered by the new {{cvt|160|hp}} [[Beardmore Halford Pullinger]] (BHP) engine, but problems with that resulted in numerous other engines being used, perhaps the best of which was the {{cvt|375|hp}} [[Rolls-Royce Eagle]] engine. The DH.4 first flew in August 1916 and it entered operational service in France on 6 March 1917 less than a year later. The majority were manufactured as general purpose two-seaters in the [[United States]] for the American expeditionary forces in France, becoming the only American made plane to see combat in WW1.

Following the [[Armistice of 11 November 1918]], many DH.4s were sold to civil operators where it was found to be particularly useful as a [[mailplane]]. Early commercial passenger airplane service in Europe was initiated with modified variants of the DH-4. War-surplus DH-4s became key aircraft in newly emerging air forces throughout the world. The U.S. Army later had several companies re-manufacture its remaining DH.4s to DH.4B standard and they operated the type into the early 1930s.

==Development==
===Origins===
The DH.4 was designed by Geoffrey de Havilland as a light two-seat combat aircraft, intended to perform both [[Bomber#The first bombers|day bomber]] and [[aerial reconnaissance]] missions.<ref name=BruceP3/> The intention was for it to be powered by the newly developed {{cvt|160|hp}} [[Beardmore Halford Pullinger]] (BHP) engine. The DH.4 was developed in parallel to the rival [[Bristol F.2 Fighter|Bristol Fighter]].<ref name=BruceP3>Bruce, 1966, p.3</ref> During August 1916, the prototype DH.4 made its first flight, powered by a prototype {{cvt|230|hp}} BHP engine.<ref name=JacksonP53>Jackson, 1987, p.53</ref>

Initial flight tests revealed it to have favourable handling and performance.<ref name=BruceP4/> The [[Central Flying School]] (CFS) conducted early evaluation flights using the prototype, leading to it producing a favourable report on the aircraft, observing good stability in flight, light flying controls and its relatively comfortable crew positions. During its flights with the CFS, it was able to attain previously unheard-of time-to-altitude figures, unmatched by any of its predecessors.<ref name=BruceP4/> While flying trials with the prototype had been producing promising results, it soon became clear that the BHP engine would require a major redesign prior to entering production.<ref name=BruceP4>Bruce, 1966, p.4</ref>

Even by the time of flying trials with the first prototype, there had been no finalised plans for quantity production of the BHP engine.<ref name=BruceP4/> Coincidentally, another suitable and promising aeroengine, the water-cooled [[Rolls-Royce Eagle]] in-line engine, was approaching the end of its development process.<ref name=BruceP3/> According to Bruce, the Eagle shared the same basic configuration as the BHP engine, which greatly aided in its adoption by de Havilland, as did the engine's endorsement by [[William Beardmore, 1st Baron Invernairn|William Beardmore]]. During the summer of 1916, a second prototype, equipped with the Rolls-Royce engine, conducted its first flight.<ref name=BruceP4/>

In response to its favourable performance, the [[Royal Flying Corps]] (RFC) decided to place an initial order for the type during late 1916.<ref name=BruceP3-4/> Separately to the RFC's interactions with the DH.4, it had received substantial interest from the [[Royal Navy]] as well.<ref name=BruceP5/> The [[British Admiralty|Admiralty]] decided to order a further pair of prototypes, configured to suit the service's own requirements, for evaluation purposes; however, according to Bruce, it is unlikely that the second of these was ever constructed. Following trials with the first of these prototypes, orders were placed for the production of DH.4s to equip the [[Royal Naval Air Service]].<ref name=BruceP5>Bruce, 1966, p.5</ref>

===Production===
[[File:EarlyDH4.jpg|thumb|An early production DH.4]]
During late 1916, the first order for 50 DH.4s, powered by {{cvt|250|hp}} Eagle III engines, was received from the RFC.<ref name=Mason/> According to Bruce, it was not a surprise to most observers that the Eagle had been selected to power the first batch of production DH.4s.<ref name=BruceP3-4/> The initial production aircraft were largely identical to the second prototype, the main difference being the adoption of armament, which included a single synchronised {{cvt|0.303|in|1}} [[Vickers machine gun]] for the pilot, while the observer was provided with a {{cvt|0.303|in}} [[Lewis gun]] mounted upon a [[Scarff ring]].<ref name=BruceP4-5>Bruce, 1966, pp.4–5</ref>

Production of the DH.4 was performed by a variety of companies beyond Airco themselves; these included F.W. Berwick and Co, Glendower Aircraft Company, Palladium Autocars, Vulcan Motor and Engineering, and the [[Westland Aircraft|Westland Aircraft Works]].<ref name=BruceP10/> By the end of production, a total of 1,449 aircraft (from orders for 1,700 aircraft) were constructed in Britain for the [[Royal Flying Corps]] (RFC) and the [[Royal Naval Air Service]] (RNAS).<ref name=JacksonP54>Jackson, 1987, p.54</ref> Overseas, [[SABCA]] of [[Belgium]] produced a further 15 DH.4s during 1926.<ref name=JacksonP60>Jackson, 1987, p.60</ref><ref name=BruceP10/>

As production progressed, various changes and improvements to the design were introduced upon the DH.4.<ref name=BruceP5/> As time went on, production DH.4s were fitted with Eagle engines of increasing power, ending with the {{cvt|375|hp}} Eagle VIII, which powered the majority of frontline DH.4s by the end of 1917. However, this transition was greatly hindered as by January 1917, it had become clear that there was a chronic shortage of Rolls-Royce aero engines, and of the Eagle in particular; it has been claimed by Bruce that this shortfall was partially the result of protracted decision-making on the part of the Air Board.<ref name=BruceP5/>

In response to the limited availability of the Eagle, extensive investigations into the use of alternative engines for the DH.4 were conducted. This resulted in aircraft being outfitted with a diverse range of engines; these included the BHP ({{cvt|230|hp}}, the [[Royal Aircraft Establishment|Royal Aircraft Factory]] [[RAF 3|RAF3A]] ({{cvt|200|hp}}), the [[Siddeley Puma]] ({{cvt|230|hp}}) and the {{cvt|260|hp}} [[Fiat]], all of which were used to power production aircraft, with varying degrees of success.<ref name=Mason/> None of these engines proved to be capable of matching the performance of the Eagle engine, which remained the preferred options despite the persistent supply constraints.<ref name=BruceP5-8>Bruce, 1966, pp.5–8</ref>

===American versions===
[[File:Assembling liberty planes at Romorantin (cropped).jpg|thumb|American DH.4 planes being assembled in France during World War One]]
At the time of entry of the [[United States]] into the First World War on 6 April 1917, the aviation section of the [[Aviation Section, U.S. Signal Corps|U.S. Signal Corps]] was unprepared, not being equipped with any aircraft suitable for combat.<ref name=BowersP3/> However, considerable optimism and energy was put into addressing this identified need, leading to the mobilization of American industry to set about the production of contemporary combat aircraft. As there were no suitable aircraft domestically, a technical commission, known as the Bolling Commission, was dispatched to Europe to seek out the best available combat aircraft and to make arrangements to enable their production to be established in the United States.<ref name=BowersP3>Bowers, 1966, p.3</ref>
As a result of the efforts of the Bolling Commission, the DH.4, along with the [[Bristol F.2 Fighter]], the [[Royal Aircraft Factory S.E.5]], and French [[SPAD S.XIII]] were selected.<ref name=BowersP3/> On 27 July 1917, a single DH.4 was sent to the United States as a pattern aircraft. It was not until 1918 that the first American-built DH.4s came off the production line.<ref name=BowersP3-10>Bowers, 1966, pp.3, 10</ref> Several different manufacturers, including the [[Boeing|Boeing Airplane Corporation]], [[Dayton-Wright Company]], the [[Fisher Body|Fisher Body Corporation]], and the [[Standard Aircraft Corporation]] produced this Americanized variant of the DH.4, featuring over 1,000 modifications from the original British design, to equip the American air services.<ref name=BowersP3-4>Bowers, 1966, pp.3–4</ref> A total of 9,500 DH.4s were ordered from American manufacturers, of which 1,885 actually reached France during the war. In American production, the new [[Liberty L-12|Liberty engine]], which had proved suitable as a DH.4 power plant, was adopted. The Liberty was also eventually adopted by the British to power the [[Airco DH.9A|DH.9A]] variant of the type.<ref name=JacksonP58>Jackson, 1987, p.58</ref><ref name=BowersP6-7>Bowers, 1966, pp.6–7</ref>

After the war, a number of firms, most significant of these being [[Boeing]], were contracted by the U.S. Army to remanufacture surplus DH.4s to the improved DH.4B standard. Internally referred to by Boeing as the '''Model 16''', deliveries of 111 aircraft from this manufacturer took place between March and July 1920; reportedly, roughly 50 of these were returned for further refurbishments three years later.<ref name=BowersP67>Bowers, 1989, p.67</ref><ref name=BowersP7-8>Bowers, 1966, pp.7–8</ref>

During 1923, the Army placed an order for a new DH.4 variant from Boeing, distinguished by a fuselage of fabric-covered steel tube in place of the original plywood structure.<ref name=BowersP9>Bowers, 1966, p.9</ref> These three prototypes were designated '''DH.4M-1''' (M for modernized) and were ordered into production alongside the generally similar '''DH.4M-2''' developed by [[Atlantic Aircraft]]. A total of 22 of the 163 DH.4M-1s were converted by the Army into dual-control trainers ('''DH.4M-1T''') and a few more into target tugs ('''DH.4M-1K'''). Thirty of the aircraft ordered by the Army were diverted to the Navy for Marine Corps use, these designated '''O2B-1''' for the base model, and '''O2B-2''' for aircraft equipped for night and [[cross-country flying]].<ref name=BowersP70>Bowers, 1989, p.70</ref>

==Design==
[[File:"Strength tests on DH-4 airplane wing ribs Project-L-225-2" from- Forest Products Laboratory for Research Work during the war. Illustrating the development in designing a wing rib for De Haviland airplane - NARA - 17341228 (cropped).jpg|thumb|Strength tests on various DH-4 wing ribs during World War I]]
The Airco DH.4 was a conventional tractor [[Interplane strut|two bay]] biplane of all-wooden construction.<ref name=BruceP3/> It was entirely built of traditional materials. The forward fuselage section and the underside of the tail area was covered by a 3mm [[plywood]] skin; this construction led to the fuselage being both strong and lightweight, heavily contributing to cross-bracing only being used for the four bays directly behind the rear cockpit.<ref name=BruceP3/> The nose of the aircraft was considerably longer than necessary, the cowling having been originally designed to accommodate the [[Beardmore Halford Pullinger]] (BHP) engine, rather than the [[Rolls-Royce Eagle]] that was adopted for production instead.<ref name=BruceP3/>

The DH.4 was powered by a variety of engines, including the Eagle, the BHP, the American [[Liberty L-12|Liberty]], [[Royal Aircraft Establishment|Royal Aircraft Factory]] [[RAF 3|RAF3A]], the [[Siddeley Puma]] and the [[Fiat]].<ref name=BruceP3/> Regardless of the engine used, it drove a four-bladed [[propeller]] mounted upon the nose. Cooling for the engine was provided via an oval-shaped radiator, while a port-mounted exhaust manifold discarded waste emissions above the upper wing.<ref name=BruceP3/> An unusual modification featuring on a small proportion of production DH.4s was the inversion of the engine, a design change that had been implemented in order to better accommodate the relatively-tall Ricardo-Halford-Armstrong (RHA) [[supercharger|supercharged]] engine, which would otherwise unduly obstruct the pilot's forward field of view.<ref name=BruceP5-8/>

The DH.4 was operated by a crew of two, who were accommodated in widely spaced cockpits, between which the fuel tank was positioned.<ref name=Mason/> While the crew arrangement provided good fields of view for both the pilot and observer; however, it had the noticeable downside of causing communication problems between the two crew members, particularly during combat situations, where the [[speaking tube]] that linked the two cockpits was of only limited use.<ref name=BruceP507>Bruce, 1952, p.507</ref><ref name=BruceP3-4>Bruce, 1966, pp.3–4</ref> On the majority of American-built aircraft, the pilot's seating and fuel tank arrangement were switched around; aviation author Peter M Bowers credits this change with improving the pilot's safety in the event of a crash, as well as allowing for better communication with the observer.<ref name=BowersP7>Bowers, 1966, p.7</ref>

The DH.4 was armed with a single forward-firing synchronised [[Vickers machine gun]] along with either one or two {{cvt|.303|in|1}} [[Lewis gun]]s fitted on a [[Scarff ring]] fired by the observer. In terms of bomb load, it accommodate a maximum payload of {{cvt|460|lb}}, which could be mounted upon external racks.<ref name=BruceP507/> Throughout the type's production life, a number of alterations to the armaments, such as the ergonomics of the observer's Lewis gun and the installation of an additional Vickers gun, were implemented.<ref name=BruceP5-8/> A pair of DH.4s were outfitted with [[COW 37 mm gun]]s for experimental purposes, but the war came to a close prior to firing trials being conducted.<ref name=BruceP10/> All armaments would typically be removed from those DH.4s that were used by civil operators, including ex-military aircraft that were sold on in great numbers following the end of the Great War.

One of the more elaborate modifications of the DH.4 was the adaptation of the type as a seaplane.<ref name=BruceP10/> It was furnished with large [[Float (nautical)|floats]], which were allegedly based upon the design of those used upon the German [[Hansa-Brandenburg W.29]] seaplane. According to Bruce, while no such aircraft entered into operational service as a result of competition from other aircraft to perform the role, a number of DH.4 seaplanes were produced for trial purposes at [[Felixstowe]] and were successfully flown.<ref name=BruceP10>Bruce, 1966, p.10</ref>

==Operational history==

===British military service===
The DH.4 entered service with the RFC in January 1917, first being used by [[No. 55 Squadron RAF|No. 55 Squadron]].<ref name=Mason/> More squadrons were equipped with the type to increase the bombing capacity of the RFC, with two squadrons re-equipping in May, and a total of six squadrons by the end of the year.<ref name=Mason/><ref name=BruceP9>Bruce, 1966, p.9</ref> During late 1917, the uptake of the type by the RFC was accelerated due to a desire to launch retaliatory bombing raids upon Germany following such attacks having been conducted against the British mainland. While [[Russia]] had been an early customer for the DH.4, having ordered 50 of the type in September 1917, the Russian and British governments subsequently agreed to delay the former's deliveries, instead diverting those aircraft to RFC squadrons in France.<ref name=BruceP7-8>Bruce, 1966, pp.7–8</ref>

As well as the RFC, the RNAS also used the DH.4. During the spring of 1917, [[No. 2 Squadron RAF|No. 2 Squadron]] became the first unit of the service to receive examples of the type.<ref name=BruceP9/> The RNAS flew their DH.4s over both [[France]] and over [[Italy]], specifically the [[Aegean Sea|Aegean]] front in the latter case.<ref name=Mason/> The DH.4 was typically used to conduct coastal patrols by the RNAS. One such flight, crewed by the pilot [[Major (rank)|Major]] [[Egbert Cadbury]] and [[Captain (land)|Captain]] [[Robert Leckie (aviator)|Robert Leckie]] (later Air Vice-Marshal) as gunner, shot down [[Zeppelin]] ''L70'' on 5 August 1918.<ref name=ThetNavyP86>Thetford 1978, p.86</ref> In another incident, a group of four RNAS DH.4s were jointly credited with the sinking of the German [[U-boat]] [[SM UB 12|''UB 12'']] on 19 August 1918.<ref name=ThetNavyP86/><ref name=BruceP9-10>Bruce, 1966, pp.9–10</ref>

The DH.4 proved a huge success and was often considered the best single-engined bomber of World War I.{{#tag:ref|Quote: "Certainly the DH.4 was without peer among the day-bombing aeroplanes used by the aerial forces of any of the combatant nations."<ref name=BruceP507/>|group=Note}} Even when fully loaded with bombs, with its reliability and impressive performance, the type proved highly popular with its crews. The Airco DH.4 was easy to fly, and especially when fitted with the Rolls-Royce Eagle engine, its speed and altitude performance gave it a good deal of invulnerability to German fighter interception,<ref name=JacksonP54-56>Jackson, 1987, pp.54–56</ref> so that the DH.4 often did not require a fighter escort on missions, a concept furthered by [[de Havilland]] in the later [[de Havilland Mosquito|Mosquito]] of the Second World War.

A drawback of the design was the distance between pilot and observer, as they were separated by the large main fuel tank. This made communication between the crew members difficult, especially in combat with enemy fighters.<ref name=JacksonP56>Jackson, 1987, p.56</ref> There was also some controversy (especially in American service) that this placement of the fuel tank was inherently unsafe.<ref name=Maurer>Maurer, 1979, pp.12, 87, 120, 132</ref><ref name=BowersP5-6>Bowers, 1966, pp.5–6</ref> In fact, most contemporary aircraft were prone to catching fire in the air.{{#tag:ref|Sometimes derided as the "Flaming Coffin," ''Gorrell's History of the Air Service of the AEF'' refuted the misconception. Quote: "Of 33 DH-4s lost to enemy action by the US Air Service, eight fell in flames- no worse than the average at the time."<ref>Williams, 1999, p.83</ref>|group=Note}} The fire hazard was reduced, however, when the pressurised fuel system was replaced by one using wind-driven fuel pumps late in 1917,<ref name=JacksonP56/> although this was not initially adopted by American-built aircraft.<ref name=MaurerP551>Maurer, 1979, p.551</ref> The otherwise inferior [[Airco DH.9|DH.9]] brought the pilot and observer closer together by placing the fuel tank in the usual place, between the pilot and the engine.

Despite its success, numbers in service with the RFC actually started to decline from spring 1918, mainly due to a shortage of engines, and production switched to the DH.9, which turned out to be disappointing, being inferior to the DH.4 in most respects. It was left to the further developed [[Airco DH.9A|DH.9A]], with the American Liberty engine, to satisfactorily replace the DH.4.

When the [[Independent Air Force]] was set up in June 1918 to carry out [[strategic bombing]] of targets in [[Germany]], the DH.4s of 55 Squadron formed part of it, being used for daylight attacks.<ref name=BruceP507/> 55 Squadron developed tactics of flying in wedge formations, bombing on the leader's command and with the massed defensive fire of the formation deterring attacks by enemy fighters.<ref name=WilliamsP84>Williams, 1999, p.84</ref> Despite heavy losses, 55 Squadron continued in operation, the only one of the day bombing squadrons in the Independent Force which did not have to temporarily stand down owing to aircrew losses.<ref name=WilliamsP195>Williams, 1999, p.195</ref>

After the [[Armistice with Germany (Compiègne)|Armistice]], the RAF formed [[No. 2 Communication Squadron RAF|No. 2 Communication Squadron]], equipped with DH.4s to carry important passengers to and from the [[Paris Peace Conference, 1919|Paris Peace Conference]]. Several of the DH.4s used for this purpose were modified with an enclosed cabin for two passengers at the request of [[Bonar Law]].<ref name=JacksonP77>Jackson, 1987, p.77</ref> One of these planes was extensively used by Prime Minister [[David Lloyd George]] and was sometimes called ''Lloyd George's airplane'' - probably the first aeroplane widely used by a political leader.<ref>{{Cite journal|date=April 1919|title=Foreign Passenger-Carrying Aeroplanes Introduce a New Era of Transportation|url=https://babel.hathitrust.org/cgi/pt?id=uc1.a0013490313&view=1up&seq=554|journal=Popular Mechanics Magazine|volume=31|pages=510–511}}</ref><ref>{{Cite journal|date=July 1919|title=British Premier's Altered DH-4 Shows Unusual Speed|url=https://babel.hathitrust.org/cgi/pt?id=uc1.a0013490321&view=1up&seq=131|journal=Popular Mechanics Magazine|volume=32|pages=65}}</ref> Modified aircraft were designated DH.4A, with at least seven being converted for the RAF, and a further nine for civil use.<ref name=JacksonP81>Jackson, 1987, p.81</ref>

===United States military service===
At the time of its entry into the war, the [[United States Army Air Service]] lacked any aircraft suitable for front line combat. It therefore procured various aircraft from the British and French, one being the DH.4. As the '''DH-4''', it was manufactured mostly by Dayton-Wright and Fisher Body for service with the United States from 1918, the first American built DH-4 being delivered to France in May 1918, with combat operations commencing in August 1918.<ref name=USAFFactsheet>[http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?fsID=324 "Fact Sheets: De Havilland DH-4."] {{webarchive|url=https://web.archive.org/web/20090114034557/http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?fsID=324 |date=14 January 2009 }} ''National Museum of the USAF''. Retrieved: 19 April 2008.</ref><ref name=BowersP6>Bowers, 1966, p.6</ref> The powerplant was a {{cvt|400|hp}} [[Liberty L-12]] and it was fitted with two forward-firing {{cvt|.30|in|2}} [[Synchronization gear|synchronized]] [[M1895 Colt–Browning machine gun#Marlin Rockwell M1917/M1918 versions|Marlin-Rockwell M1917]] (a development of the [[M1895 Colt–Browning machine gun|Colt-Browning]]) machine guns in the nose and two {{cvt|.30|in|2}} [[Lewis gun]]s in the rear and could carry {{cvt|322|lb}} of bombs. it could also be equipped with various radios like the [[SCR-68]] for artillery spotting missions. The heavier engine reduced performance compared with the Rolls-Royce powered version, but as the "Liberty Plane" it became the US Army Air Service standard general purpose two-seater, and on the whole was fairly popular with its crews. 
[[File:A Concise History of the U.S. Air Force Page 06-1.jpg|thumb|A formation of DH-4s in flight]]

Aircrew operating the DH-4 were awarded four of the six [[Medal of Honor|Medals of Honor]] awarded to American aviators. [[First Lieutenant#U.S. Army, U.S. Marine Corps and U.S. Air Force|First Lieutenant]] [[Harold Ernest Goettler]] and [[Second Lieutenant]] [[Erwin R. Bleckley]] received posthumous awards after being killed on 12 October 1918 attempting to drop supplies to the [[Lost Battalion (World War I)|Lost Battalion]] of the [[77th Infantry Division (United States)|77th Division]], cut off by German troops during the [[Meuse-Argonne Offensive]];<ref name=USAFFactsheet/> while Second Lieutenant [[Ralph Talbot]] and [[Gunnery Sergeant]] [[Robert G. Robinson]] of the [[United States Marine Corps]] (USMC) were awarded the Medal of Honor for beating off attacks from 12 German fighters during a bombing raid over Belgium on 8 October 1918.<ref name=Workhorse>[http://www.airpower.au.af.mil/airchronicles/apj/apj02/win02/notam5.pdf "The De Havilland DH-4, Workhorse of the Army Air Service."] {{Webarchive|url=https://web.archive.org/web/20080528183809/http://www.airpower.au.af.mil/airchronicles/apj/apj02/win02/notam5.pdf |date=28 May 2008 }} ''Air & Space Power Journal'', Winter 2002. Retrieved: 9 May 2008.</ref><ref>[http://www.arlingtoncemetery.net/rrobin.htm "Robert Guy Robinson, First Lieutenant, United States Marine Corps."] at ArlingtonCemetery.net (Unofficial website).</ref>{{Better source needed|date=January 2021|reason=attribution of the original material is needed and preferred}} The type flew with 13 U.S. squadrons by the end of 1918.<ref name=AngelucciP79>Angelucci, 1981, p.79</ref>

Following the end of the First World War, America had a large surplus of DH-4s, with the improved DH-4B becoming available, although none had been shipped to France. It was therefore decided that there was no point in returning aircraft across the Atlantic, so those remaining in France, together with other obsolete observation and trainer aircraft, were burned in what became known as the "Billion Dollar Bonfire".<ref name=SwanSince1909P198>Swanborough and Bowers, 1963, p.198</ref><ref name=BowersP6/> With limited funds available to develop and purchase replacements, the remaining DH-4s formed a major part of American air strength for several years, used for many roles, with as many as 60 variants produced.<ref name=BruceP510>Bruce, 1952, p.510</ref> DH-4s were also widely used for experimental flying, being used as engine testbeds and fitted with new wings. They were used for the first trials of [[Aerial refueling|air-to-air refueling]] on 27 June 1923, and one carried out an endurance flight of 37 hours, 15 minutes on 27–28 August, being refueled 16 times and setting 16 new world records for distance, speed and duration.<ref>[http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=745 "Fact Sheets: Air-to-Air Refueling."] {{webarchive|url=https://web.archive.org/web/20130318015424/http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=745 |date=18 March 2013 }} ''National Museum of the United States Air Force''. Retrieved: 10 May 2008.</ref> The DH-4 remained in service with the [[United States Army Air Corps]], successor to the United States Army Air Service, until 1932.<ref name=SwanSince1909P199>Swanborough and Bowers, 1963, p.199</ref>

A large number of DH-4s were also used by the [[United States Navy]] and United States Marine Corps, both during the First World War and postwar. The Navy and Marine Corps received a total of 51 DH-4s during wartime, followed by 172 DH-4B and DH-4B-1 aircraft postwar and 30 DH-4M-1s with welded steel-tube fuselages (redesignated O2B) in 1925.<ref name=SwanNavyP156>Swanborough and Bowers, 1976, p.156</ref> They remained in service with the Marine Corps until 1929, being used against rebel factions in [[United States occupation of Nicaragua|Nicaragua]] in 1927, carrying out the first dive-bombing attacks made by U.S. military forces.<ref name=SwanNavyP156/> The U.S. Navy converted some DH-4M-1s into primitive air ambulances that could carry one stretcher casualty in an enclosed area behind the pilot.<ref>{{cite magazine|magazine=Popular Mechanics|author=Hearst Magazines|title=Help From The Skies|url=https://books.google.com/books?id=0N8DAAAAMBAJ&pg=PA765|date=November 1929|publisher=Hearst Magazines|page=765}}</ref>

===Civil use===
[[File:DH-4 airmail.jpg|thumb|Robertson Aircraft Corp. operated DH-4 mailplane (CAM 2) 1926 at the [[Historic Aircraft Restoration Museum]]]]

Following the end of the First World War, large numbers of DH.4s and DH.4As were used to operate scheduled passenger services in Europe by such airlines as [[Aircraft Transport and Travel]], [[Handley Page Transport]] and the Belgium airline [[SNETA]]. ''G-EAJC'' of Aircraft Transport and Travel flew the first British commercial passenger service from [[Hounslow Heath Aerodrome]] to [[Paris–Le Bourget Airport|Paris Le Bourget]] on 25 August 1919, carrying a reporter from the ''[[London Evening Standard|Evening Standard]]'' newspaper and a load of newspapers and other freight.<ref name=CivilSince1919P41>Jackson, 1973, p.41</ref><ref name=DHsince1909P79>Jackson, 1987, p.79</ref> They were used by Aircraft Transport and Travel until it shut down in 1920, while Handley Page Transport and SNETA continued operating the DH.4 until 1921. One aircraft was used by [[Instone Air Line]]s until its merger into [[Imperial Airways]] in 1924.<ref name=CivilSince1919P43>Jackson, 1973, p.43</ref>

[[File:DeHavilland Biplane stamp 24c 1923 issue.JPG|thumb|244px|left|In 1923 the U.S. Post Office released a stamp featuring the DeHavilland Biplane being used for airmail service<ref>{{cite news |title=24-cent DeHavilland Biplane |publisher=Smithsonian National Postal Museum}}</ref>]]

On September 4, 1922, [[Jimmy Doolittle]] made the first cross-country flight, flying a de Havilland DH-4 – which was equipped with early navigational instruments – from Pablo Beach (now [[Jacksonville Beach]]), Florida, to [[Rockwell Field]], San Diego, California, in 21 hours and 19 minutes, making only one refueling stop at [[Kelly Field]].

The DH.4 were also used by the [[Australia]]n airline [[Qantas|QANTAS]], flying its first [[airmail]] service in 1922.<ref name=CivilSince1919P40>Jackson, 1973, p.40</ref> Twelve DH.4s forming part of the [[Imperial Gift]] to [[Canada]] were used for forestry patrol and survey work, spotting hundreds of forest fires and helping to save millions of dollars worth of timber, with the last example finally being withdrawn in 1927.<ref name=DHsince1909P70-71>Jackson, 1973, pp.70–71</ref><ref name=BruceP10/>

The [[United States Postal Service|U.S. Post Office]] also adopted the DH-4 to carry air mail.<ref name=Postal>{{cite web |first1=Nancy A. |last1=Pope |url=http://postalmuseum.si.edu/exhibits/current/airmail-in-america/the-airplanes/dehavilland-dh-4.html |title=deHavilland DH-4 |publisher=[[National Postal Museum]], [[Smithsonian Institution]] |access-date=21 July 2015 |archive-url=https://web.archive.org/web/20150706021849/http://postalmuseum.si.edu/exhibits/current/airmail-in-america/the-airplanes/dehavilland-dh-4.html |archive-date=6 July 2015 |url-status=dead }}</ref><ref name=BowersP9-10>Bowers, 1966, pp.9–10</ref> The Service acquired 100 of them from the army in 1918, and retrofitted them to make them safer, denominating them as the DH.4B.<ref name=Postal/> In 1919, the DH-4B was standardised by the US Post Office, being modified to be flown from the rear cockpit with a {{cvt|400|lb}} watertight mail compartment replacing the forward cockpit. The airmail DH-4B were later modified with revised landing gear and an enlarged [[rudder]].<ref name=SwanSince09P201>Swanborough and Bowers, 1963, p.201</ref> DH-4s were used to establish a coast-to-coast, transcontinental airmail service, between San Francisco and New York, a distance of {{cvt|2680|mi}}, involving night flight, the first services starting on 21 August 1924. The DH-4 continued in Post Office service until 1927, when the last airmail routes were passed to private contractors.<ref name=BowersP10>Bowers, 1966, p.10</ref>{{clear}}

War-surplus DH-4s were available cheaply in sufficient quantities to stimulate the development of "utility aviation": surveying, commercial photography, law enforcement, agricultural applications and other practical applications.<ref name="britannica">[https://www.britannica.com/technology/history-of-flight/General-aviation "General Aviation,"] in "History of Flight", ''Britannica'', retrieved May 29, 2021</ref>

==Variants==
[[File:Airco DH-4.jpg|thumb|DH-4 soaring above the clouds in France]]
[[File:Wright Radial Engine in a De Havilland DH-4B airplane (00910460 163).jpg|thumb|Wright Radial Engine (R-1) fitted to a De Havilland DH-4B airframe]]

===UK variants===
* '''DH.4''' : Two-seat day bomber biplane.
* '''DH.4A''' : Transport version. Built in the United Kingdom. Two passengers in glazed cabin behind pilot.
* '''DH.4R''' : Single seat racer – {{cvt|450|hp}} [[Napier Lion]] engine.

===Soviet variants===
* copy of DH.4 manufactured by [[Polikarpov]] in the former [[Dux Factory]] in the 1920s

===United States variants===
<ref name=JacksonP67>Jackson, 1987, p.67</ref>
* '''DH-4''' : Two-seat day bomber biplane, built in the United States.
* '''DH-4A''' : Civil version, built in the United States.
* '''DH-4B''' : Rebuilt version of Liberty powered DH-4 for [[United States Army Air Service|U.S. Air Service]]. Pilot's cockpit relocated to behind fuel tank, adjacent to observer's cockpit.
*** '''DH-4B-1''' : Increased fuel capacity ({{cvt|110|usgal}}).
*** '''DH-4B-2''' : Trainer version.
*** '''DH-4B-3''' : Fitted with {{cvt|135|usgal}} fuel tank
*** '''DH-4B-4''' : Civil version
*** '''DH-4B-5''' : Experimental civil conversion with enclosed cabin.
** '''DH-4BD''' :Cropdusting version of DH-4B
** '''DH-4BG''' : Fitted with smokescreen generators
** '''DH-4BK''' : Night flying version
** '''DH-4BM''': Single seat version for communications
*** '''DH-4BM-1''' : Dual control version of BM
*** '''DH-4BM-2''' : Dual control version of BM
** '''DH-4-BP''' : Experimental photo reconnaissance version
*** '''DH-4-BP-1''' : BP converted for survey work
** '''DH-4BS''' : Testbed for supercharged Liberty
** '''DH-4BT''' : Dual control trainer
** '''DH-4BW''' : Testbed for Wright H engine
* '''DH-4C''' : {{cvt|300|hp}} Packard engine
* '''DH-4L''' : Civil version
* '''DH-4M''' : Rebuilt version of DH-4 with steel tube fuselage.
* '''DH-4Amb''' : Ambulance.
* '''DH-4M-1''' – postwar version by Boeing (Model 16) with new fuselage, designated '''O2B-1''' by Navy
** '''DH-4M-1T''' – Dual control trainer conversion of DH-4M
** '''DH-4M-1K''' – target tug conversion
** '''O2B-2''' – cross-country and night flying conversion for Navy
* '''DH-4M-2''' – postwar version by Atlantic
* '''L.W.F. J-2''' – Twin-engine long range development of DH-4 (also known as '''Twin DH'''), powered by two {{cvt|200|hp}} [[Hall-Scott]]-[[Liberty L-6]] engines and with wingspan of {{cvt|52|ft|6|in}}; 20 built for U.S. Post Office, 10 for U.S. Army.<ref>[http://www.aerofiles.com/_lo.html "American airplanes: Lo – Lu."] {{Webarchive|url=https://web.archive.org/web/20080421224309/http://www.aerofiles.com/_lo.html |date=21 April 2008 }} ''Aerofiles''. Retrieved: 10 May 2008.</ref><ref name=SwanSince09P202-203>Swanborough and Bowers, 1963, pp.202–203</ref>

;[[Boeing Model 42|XCO-7]] : (Boeing Model 42) Two-seat observation version with Boeing designed wings, enlarged tailplane and divided landing gear.

;XCO-8
:Was a designation of one Atlantic DH.4M-2 fitted with Loening COA-1 wings and powered by a Liberty 12A engine.

==Operators==

===Civil operators===
;{{ARG}}
*[[The River Plate Aviation Co. Ltd.]]
;{{AUS}}
*[[Qantas|QANTAS]]
;{{BEL}}
*[[SNETA]]
;{{GBR}}:
*[[Aircraft Transport and Travel|Aircraft Transport and Travel Limited]]
*[[Handley Page Transport]]
*[[Imperial Airways]]
*[[Instone Air Line]]
;{{USA}}
*[[United States Postal Service|U.S. Post Office]]

===Military operators===
;{{BEL}}
*[[Belgian Air Force|Aviation Militaire Belge]]
;{{flag|Canada|1921}}
*[[Canadian Air Force (1918–1920)]]
*[[Royal Canadian Air Force]]
;{{CHL}}
*[[Chilean Air Force]]
;{{CUB}}
*[[Cuban Air Force]] – American built DH-4s
;{{flag|Greece|old}}
*[[Hellenic Air Force]]
*[[Hellenic Navy]]
;{{flag|Iran|1925}}
*[[Imperial Iranian Air Force]]
;{{flag|Mexico|1923}}
*[[Mexican Air Force|Fuerza Aérea Mexicana]]
;{{NIC}}
*[[Nicaraguan Air Force]] – The Nicaragua Air Force received seven DH-4Bs.<ref>Klaus, Erich. [http://www.aeroflight.co.uk/waf/americas/nicaragua/Nicaragua-af-DH4.htm "Nicaragua Air Force Aircraft Types: de Havilland (Airco) DH.-4B."] {{Webarchive|url=https://web.archive.org/web/20080527231009/http://www.aeroflight.co.uk/waf/americas/nicaragua/Nicaragua-af-DH4.htm |date=27 May 2008 }} ''Aeroflight'', 1 June 2003. Retrieved: 10 May 2008.</ref>
;{{NZL}}
*The [[New Zealand Permanent Air Force]] operated two aircraft from 1919 to 1929. It was used by the NZPAF as an advanced training aircraft. The DH.4 has the distinction of being the first aircraft to fly over [[Aoraki / Mount Cook|Mount Cook]] on 8 September 1920. It also set a New Zealand altitude record of {{cvt|21000|ft}} on 27 November 1919.
;{{flag|South Africa|1912}}
*[[South African Air Force]]
;{{URS}}
*[[Soviet Air Force]]
;{{flagicon|Spain|1785}} [[Kingdom of Spain]]
*[[Spanish Air Force]]
;{{TUR}}
*[[Turkish Air Force]]
;{{GBR}}
*[[Royal Flying Corps]]
*[[Royal Air Force]]
*[[Royal Naval Air Service]]
;{{flag|United States|1912}}
*[[United States Army Air Service]]
**[[8th Aero Squadron]]
**[[11th Aero Squadron]]
**[[20th Aero Squadron]]
**[[50th Aero Squadron]]
**[[85th Aero Squadron]]
**[[91st Aero Squadron]]
**[[104th Aero Squadron]]
**[[135th Aero Squadron]]
**[[163rd Aero Squadron]]
**[[166th Aero Squadron]]
**[[168th Aero Squadron]]
**[[278th Aero Squadron]]
**[[354th Aero Squadron]]
*[[United States Navy]]
*[[United States Marine Corps]]

==Surviving aircraft==
[[File:Airco DH-4 NMUSAF.jpg|thumb|The DH-4B on display at the [[National Museum of the United States Air Force]]]]
[[File:Friends of Jenny DH.4 side view.jpg|thumb|Friends of Jenny DH.4, 2018]]
DH-4:
* 21959{{citation needed|date=May 2016}} – The prototype American-built DH-4 is on display at the [[National Air and Space Museum]] in [[Washington D.C.]]<ref>{{cite web|title=De Havilland DH-4|url=http://airandspace.si.edu/collections/artifact.cfm?object=nasm_A19190051000|website=Smithsonian National Air and Space Museum|access-date=10 May 2016|archive-url=https://web.archive.org/web/20160412103503/https://airandspace.si.edu/collections/artifact.cfm?object=nasm_A19190051000|archive-date=12 April 2016|url-status=live}}</ref>
* Unknown ID – A DH-4 is on display at the [[National Museum of the Marine Corps]] in [[Triangle, Virginia]].<ref>{{cite web|title=De Haviland DH-4|url=http://www.virtualusmcmuseum.com/Preview_3.asp|website=National Museum of the Marine Corps Virtual Experience|access-date=10 May 2016|archive-url=https://web.archive.org/web/20161220114405/http://www.virtualusmcmuseum.com/Preview_3.asp|archive-date=20 December 2016|url-status=live}}</ref> It was restored by Century Aviation.<ref>{{cite web|title=1918 DeHavilland DH-4|url=http://century-aviation.com/essential_grid/1918-dehavilland-dh-4|website=Century Aviation|access-date=10 May 2016|archive-url=https://web.archive.org/web/20160423190201/http://century-aviation.com/essential_grid/1918-dehavilland-dh-4/|archive-date=23 April 2016|url-status=live}}</ref>
* 32517 - A DH-4 is currently being reconstructed so it can be permanently displayed at the [[Wichita Dwight D. Eisenhower National Airport]] in [[Wichita, Kansas]].  It will commemorate [[United States Army]] [[aviator]] [[Erwin R. Bleckley]], who was [[killed in action]] during [[World War I]]  while flying a DH-4 near the [[Lost Battalion (World War I)|"lost battalion"]] in France.<ref>{{cite web |title=Home Page |url=https://www.bleckleyfoundation.org/ |website=Bleckley Airport Memorial Foundation (BAMF) |archive-url=https://web.archive.org/web/20240801194653/https://www.bleckleyfoundation.org/ |archive-date=August 1, 2024 |url-status=live}}</ref>
* Unknown ID – A DH-4 is on display at the Omaka Aviation Heritage Centre in [[Blenheim, New Zealand]].<ref>{{cite web|title=The Exhibits|url=http://www.omaka.org.nz/exhibits.htm|website=Omaka Aviation Heritage Centre|publisher=New Zealand Aviation Museum Trust|access-date=10 May 2016|url-status=dead|archive-url=https://web.archive.org/web/20160413022148/http://www.omaka.org.nz/exhibits.htm|archive-date=13 April 2016}}</ref> This aircraft was previously on display at the [[Crawford Auto-Aviation Museum]] in [[Cleveland, Ohio]] and was at one point loaned to the United States Air Force Museum.<ref>{{cite news|last1=Mazzolini|first1=Joan|title=Western Reserve Historical Society has sold or put up for sale many items from its collection|url=http://blog.cleveland.com/pdextra/2010/03/the_western_reserve_historical.html|access-date=11 May 2016|work=Cleveland.com|publisher=Advance Ohio|date=7 March 2010|archive-url=https://web.archive.org/web/20160818194233/http://blog.cleveland.com/pdextra/2010/03/the_western_reserve_historical.html|archive-date=18 August 2016|url-status=live}}</ref>
* Replica – A DH.4 is airworthy with The Vintage Aviator Limited in [[Masterton, New Zealand]]. It was built by Century Aviation and is powered by a rebuilt Liberty V-12.<ref>{{cite web|title=1917 Airco DH.4 (British Military)|url=http://century-aviation.com/essential_grid/1917-airco-dh-4-british-military|website=Century Aviation|access-date=10 May 2016|archive-url=https://web.archive.org/web/20161011192953/http://century-aviation.com/essential_grid/1917-airco-dh-4-british-military/|archive-date=11 October 2016|url-status=live}}</ref>
* Replica – A DH-4 is on display at the [[Museo del Aire (Madrid)|Museo del Aire]] in [[Madrid, Spain]].<ref>{{cite web|title=Fotografía De Havilland DH-4|url=http://www.ejercitodelaire.mde.es/ea/pag?idDoc=CC080F0B0240A9D7C125747A002415EA&idImg=DA4CA2CBC2AED670C125747A0024C05F|website=Ejército del Aire|access-date=10 May 2016|archive-url=https://web.archive.org/web/20160318103450/http://www.ejercitodelaire.mde.es/ea/pag?idDoc=CC080F0B0240A9D7C125747A002415EA&idImg=DA4CA2CBC2AED670C125747A0024C05F|archive-date=18 March 2016|url-status=dead}}</ref><ref>{{cite web|title=Airframe Dossier – Airco DH-4|url=http://aerialvisuals.ca/AirframeDossier.php?Serial=2981|website=Aerial Visuals|publisher=AerialVisuals.ca|access-date=10 May 2016|archive-url=https://web.archive.org/web/20161012133859/http://aerialvisuals.ca/AirframeDossier.php?Serial=2981|archive-date=12 October 2016|url-status=live}}</ref>

DH-4B:
* Unknown ID – A DH-4B is on display in the main atrium of the [[National Postal Museum]] in [[Washington, D.C.]]<ref>{{cite web|title=deHavilland DH-4|url=http://postalmuseum.si.edu/exhibits/current/airmail-in-america/the-airplanes/dehavilland-dh-4.html|website=Smithsonian National Postal Museum|access-date=10 May 2016|archive-url=https://web.archive.org/web/20160417222726/http://postalmuseum.si.edu/exhibits/current/airmail-in-america/the-airplanes/dehavilland-dh-4.html|archive-date=17 April 2016|url-status=dead}}</ref>
* Unknown ID – A DH-4B at the [[Pearson Air Museum]] in [[Vancouver, Washington]]. It was restored by Century Aviation.<ref>{{cite news|last1=Cromwell|first1=Bob|title=National Park Service Announces the Purchase of a DeHavilland DH-4 Biplane for Exhibit at Pearson Air Museum|url=https://www.nps.gov/fova/learn/news/dehavillandexhibit.htm|access-date=10 May 2016|work=National Park Service|date=15 October 2014|archive-url=https://web.archive.org/web/20160919014750/https://www.nps.gov/fova/learn/news/dehavillandexhibit.htm|archive-date=19 September 2016|url-status=live}}</ref><ref>{{cite web|title=1919 DeHavilland DH-4B|url=http://century-aviation.com/essential_grid/1919-dehavilland-dh-4b|website=Century Aviation|access-date=13 August 2016|archive-url=https://web.archive.org/web/20160423190911/http://century-aviation.com/essential_grid/1919-dehavilland-dh-4b/|archive-date=23 April 2016|url-status=live}}</ref><ref>{{cite web|title=The DH-4 Liberty Plane at War and in Peace|url=https://www.nps.gov/articles/libertyplane.htm|website=National Park Service|access-date=13 December 2023}}</ref>
* Unknown ID – A DH-4B is on display at the [[National Museum of the United States Air Force]] in [[Dayton, Ohio]].<ref>{{cite web|title=De Havilland DH-4|url=https://www.nationalmuseum.af.mil/Visit/Museum-Exhibits/Fact-Sheets/Display/Article/197397/de-havilland-dh-4/|website=National Museum of the US Air Force|access-date=10 May 2016|date=7 April 2015|archive-url=https://web.archive.org/web/20160605032142/http://www.nationalmuseum.af.mil/Visit/MuseumExhibits/FactSheets/Display/tabid/509/Article/197397/de-havilland-dh-4.aspx|archive-date=5 June 2016|url-status=live}}</ref> It was restored by Century Aviation.<ref>{{cite web|title=DeHavilland DH-4B|url=http://century-aviation.com/essential_grid/dehavilland-dh-4b|website=Century Aviation|access-date=10 May 2016|archive-url=https://web.archive.org/web/20160423190206/http://century-aviation.com/essential_grid/dehavilland-dh-4b/|archive-date=23 April 2016|url-status=live}}</ref>
* Unknown ID – A DH-4B is on display at [[Fantasy of Flight]] in [[Polk City, Florida]]. It was restored by Century Aviation.<ref>{{cite web|title=1918 DeHavilland DH-4 Mail Plane|url=http://century-aviation.com/essential_grid/1918-dehavilland-dh-4-mail-plane|website=Century Aviation|access-date=10 May 2016|archive-url=https://web.archive.org/web/20160428190047/http://century-aviation.com/essential_grid/1918-dehavilland-dh-4-mail-plane/|archive-date=28 April 2016|url-status=live}}</ref>
* Unknown ID – A DH-4B is under restoration by Century Aviation for Fantasy of Flight in Polk City, Florida. It will be powered by a rebuilt Liberty V-12.<ref>{{cite web|title=1918 De Havilland DH-4 (U.S. Army Air Corps)|url=http://century-aviation.com/essential_grid/1918-de-havilland-dh-4-u-s-army-air-corps|website=Century Aviation|access-date=10 May 2016|archive-url=https://web.archive.org/web/20160423002225/http://century-aviation.com/essential_grid/1918-de-havilland-dh-4-u-s-army-air-corps/|archive-date=23 April 2016|url-status=live}}</ref>

DH-4M-1
* Unknown ID – A DH-4M-1 is on display at the [[Evergreen Aviation and Space Museum]] in [[McMinnville, Oregon]].<ref>{{cite web|title=Airframe Dossier – Airco DH-4, c/r N3258|url=http://aerialvisuals.ca/AirframeDossier.php?Serial=70390|website=Aerial Visuals|publisher=AerialVisuals.ca|access-date=10 May 2016|archive-url=https://web.archive.org/web/20161012133848/http://aerialvisuals.ca/AirframeDossier.php?Serial=70390|archive-date=12 October 2016|url-status=live}}</ref> This aircraft was previously owned by [[Paul Mantz]].<ref>{{cite book|last1=Skaarup|first1=Harold|title=Washington Warbird Survivors 2002: A Handbook on Where to Find Them|date=1 February 2002|publisher=iUniverse|isbn=9780595216932|url=https://books.google.com/books?id=qHvpxhDOzJAC}}</ref>

DH-4M-2A
* Unknown ID – A DH-4M-2A is airworthy at the [[Historic Aircraft Restoration Museum]] in [[Maryland Heights, Missouri]].<ref>{{cite web|title=Museum Hangar 4|url=http://www.historicaircraftrestorationmuseum.org/museumhangar4.html|website=Historic Aircraft Restoration Museum|access-date=11 May 2016|archive-url=https://web.archive.org/web/20160306220901/http://www.historicaircraftrestorationmuseum.org/museumhangar4.html|archive-date=6 March 2016|url-status=live}}</ref><ref>{{cite web|title=Airframe Dossier – Airco DH-4M-2A, c/r N3249H|url=http://aerialvisuals.ca/AirframeDossier.php?Serial=141812|website=Aerial Visuals|publisher=AerialVisuals.ca|access-date=10 May 2016|archive-url=https://web.archive.org/web/20161012133829/http://aerialvisuals.ca/AirframeDossier.php?Serial=141812|archive-date=12 October 2016|url-status=live}}</ref><ref>{{cite web |title=FAA Registry [N3249H] |url=http://registry.faa.gov/AircraftInquiry/Search/NNumberResult?nNumberTxt=N3249H |website=Federal Aviation Administration |publisher=U.S. Department of Transportation |access-date=3 November 2021}}</ref><ref>{{cite web|title=DH-4M2|url=http://www.peckaeroplanerestoration.com/projects/dh-4-mail-plane|website=Peck Aeroplane Restoration|access-date=3 June 2016|archive-url=https://web.archive.org/web/20160920091101/http://www.peckaeroplanerestoration.com/projects/dh-4-mail-plane/|archive-date=20 September 2016|url-status=live}}</ref>

==Specifications (DH.4 – Eagle VIII engine)==
{{Aircraft specs
|ref=''The British Bomber since 1914'',<ref name=Mason>Mason, 1994, pp.66–69</ref> ''The de Havilland DH.4''<ref name=BruceP8-10>Bruce, 1966, pp.8, 10</ref>
|prime units?=imp
<!--General characteristics-->
|crew=2
|length ft=30||length in=8
|span ft=43||span in=4
|height ft=11||height in=0
|wing area sqft=434
|empty weight lb=2387
|gross weight lb=3472
<!--Powerplant-->
|eng1 number=1
|eng1 name=[[Rolls-Royce Eagle VIII]]
|eng1 type=water-cooled [[V12 engine]]
|eng1 hp=375<!-- prop engines -->
|eng1 note={{#tag:ref|{{cvt|230|hp}} for [[BHP Puma]]|group=Note}}
|prop blade number=<!-- propeller aircraft -->
|prop name=
|prop dia ft=||prop dia in=
|prop note=
<!--
  Performance
-->
|max speed mph=143
|max speed note=at sea level {{#tag:ref|{{cvt|106|mph}} for Puma engine variants|group=Note}}
|endurance=3 hr 45 min
|ceiling ft=22000
|time to altitude=9 min to {{cvt|10000|ft}}
<!--Armament-->
|guns=One fixed forward-firing {{cvt|.303|in|1}} [[Vickers machine gun]], 1 or 2 {{cvt|.303|in|1}} [[Lewis gun]]s on a [[Scarff ring]] 
|bombs={{cvt|460|lb}} of bombs
}}

==See also==
{{aircontent
|related=
*[[Airco DH.9]]
*[[Airco DH.9A]]
|similar aircraft=
|lists=
*[[List of bomber aircraft]]
|see also=
*[[1916 in aviation]]
}}

==References==
===Notes===
{{Reflist|group=Note}}

===Citations===
{{Reflist}}

===Bibliography===
*Angelucci, Enzo, ed. ''World Encyclopedia of Military Aircraft''. London: Jane's, 1991. {{ISBN|0-7106-0148-4}}.
*Bruce, J.M. [https://web.archive.org/web/20110520132120/http://www.flightglobal.com/pdfarchive/view/1952/1952%20-%203038.html "The De Havilland D.H.4."] [[Flight International|''Flight'']], 17 October 1952, pp.&nbsp;506–510.
*Bruce, J.M. ''The de Havilland D.H.4. (Aircraft in Profile number 26)''. London: Profile Publications, 1966. No ISBN.
*Bowers, Peter M. ''Boeing Aircraft since 1916''. London: Putnam, Second edition, 1989. {{ISBN|0-85177-804-6}}.
*Bowers, Peter M. ''The American DH.4 (Aircraft in Profile number 97)''. London: Profile Publications, 1966. No ISBN.
*Jackson, A.J. ''British Civil Aircraft since 1919: Volume 2''. London: Putnam, Second edition, 1973. {{ISBN|0-370-10010-7}}.
*Jackson, A.J. ''De Havilland Aircraft since 1909''. London: Putnam, Third edition, 1987. {{ISBN|0-85177-802-X}}.
*{{cite journal |last1=Klaauw|first1=Bart van der|title=Unexpected Windfalls: Accidentally or Deliberately, More than 100 Aircraft 'arrived' in Dutch Territory During the Great War |journal=Air Enthusiast |date=March–April 1999 |issue=80 |pages=54–59 |issn=0143-5450}}
*Mason, Francis K. ''The British Bomber since 1914''. London: Putnam Aeronautical Books, 1994. {{ISBN|0-85177-861-5}}.
*Maurer, Maurer, ed. ''The U.S. Air Service in World War I: Volume IV Postwar Review''. Washington, D.C.: The Office of Air Force History Headquarters USAF, 1979.
*{{cite magazine|last=Prins|first=François|title=Pioneering Spirit: The QANTAS Story |magazine=[[Air Enthusiast]] |date=Spring 1994|issue=53 |pages=24–32 |issn=0143-5450}}
*Sturtivant, Ray and Gordon Page. ''The D.H.4/D.H.9 File''. Tonbridge, Kent, UK: Air-Britain (Historians) Ltd., 2000. {{ISBN|0-85130-274-2}}.
*Swanborough, F.G. and Peter M. Bowers. ''United States Military Aircraft since 1909''. London: Putnam, 1963.
*Swanborough Gordon and Peter M. Bowers. ''United States Naval Aircraft since 1911''. London: Putnam, Second edition, 1976. {{ISBN|0-370-10054-9}}.
*Thetford, Owen. ''British Naval Aircraft since 1912''. London: Putnam, Fourth edition, 1978. {{ISBN|0-370-30021-1}}.
*Thomas, Andrew. "In the Footsteps of Daedulus: Early Greek Naval Aviation". ''Air Enthusiast'', No. 94, July–August 2001, pp.&nbsp;8–9. {{ISSN|0143-5450}}
*''United States Air Force Museum Guidebook''. Wright-Patterson AFB, Ohio: Air Force Museum Foundation, 1975.
*{{cite journal |last1=Wauthy|first1=Jean-Luc|last2=de Neve|first2=Florian|name-list-style=amp|title=Les aéronefs de la Force Aérienne Belge, deuxième partie 1919–1935|journal=Le Fana de l'Aviation |date=June 1995 |issue=305 |pages=28–33 |issn=0757-4169|language=fr|trans-title=Aircraft of the Belgian Air Force}}
* Williams, George K. ''Biplanes and Bombsights: British Bombing in World War I''. Maxwell Air Force Base, Alabama: Air University Press, 1999. {{ISBN|1-4102-0012-4}}.

==External links==
{{Commons category}}
* [http://www.opencockpit.net/dh4/dh4.html "Pilot Report, The deHavilland DH4: A Trip Back In Time,"] by Addison Pemberton
* [http://harris1.net/hold/av/avhist/a8/a8_dh4.htm "Chapter 3: The Airco/deHavilland DH-4,"] in ''Eight Great Aircraft,'' by Richard Harris.

{{De Havilland aircraft}}
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[[Category:Airco aircraft|DH.004]]
[[Category:1910s British bomber aircraft]]
[[Category:Single-engined tractor aircraft]]
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[[Category:Atlantic Aircraft aircraft]]
[[Category:Aircraft first flown in 1916]]
[[Category:L-W-F aircraft]]
[[Category:Aircraft with fixed conventional landing gear]]
[[Category:Single-engined piston aircraft]]