View source for Siemens-Schuckert D.IV

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{{Infobox aircraft
|name           = Siemens-Schuckert D.IV
|image          = File:Siemens-Schuckert D.III.jpg
|caption        = Siemens-Schuckert D.III on display at the Luftwaffe Museum at Gatow
|type           = [[Fighter aircraft]]
|national_origin = [[Germany]]
|manufacturer   = [[Siemens-Schuckert]]
|designer       = <!--Only appropriate for single designers, not project leaders-->
|first_flight   = 1918<!--If this hasn't happened, skip this field!-->
|introduction   = 1918<!--Date the aircraft entered or will enter military or revenue service-->
|retired        = <!--Date the aircraft left service. If vague or more than a few dates, skip this -->
|status         = <!--In most cases, redundant; use sparingly -->
|primary_user   = Germany<!-- list only one user; for military aircraft, this is a nation or a service arm. Please DON'T add those tiny flags, as they limit horizontal space. -->
|more_users     = <!--Limited to three in total; separate using <br> -->
|produced       = <!--Years in production (eg. 1970-1999) if still in active use but no longer built -->
|number_built   = 123 (by the end of the war)
|program cost   = <!--Total program cost-->
|unit cost      = <!--Incremental or flyaway cost for military or retail price for commercial aircraft-->
|developed_from = <!--The aircraft which formed the basis for this aircraft-->
|variants = <!--Variants OF this aircraft-->
}}
The '''Siemens-Schuckert D.IV''' was a late-[[World War I]] [[fighter aircraft]] from [[Siemens-Schuckert]] (SSW). It reached service too late and was produced in too few numbers to have any effect on the war effort.
==Earlier designs==
Siemens-Schuckert's first production fighter aircraft was the [[Siemens-Schuckert D.I]], which was based closely on the French [[Nieuport 17]]. Apart from the use of the Siemens-Halske Sh.I, a geared rotary engine in which the crankshaft and the propeller rotated in opposite directions, the D.I was in fact a fairly close copy of the Nieuport. By the time production D.Is appeared in 1917 however, the design was no longer competitive and after 95 had been built, production was cancelled, with the type serving mainly as an advanced trainer.
Development work on the Siemens-Halske Sh.I culminated in the [[Siemens-Halske Sh.III]], which developed {{cvt|160|PS|kW hp}}. The new engine was fitted to a series of original prototype designs from the SSW works, the D.II, D.IIa and D.IIb. These featured a short, round section fuselage designed to fit a larger engine, leading to a rather stubby-looking aircraft which pilots later referred to as ''the flying beer barrel''. Flight tests started in June 1917, and while the aircraft did not have a very high top speed, they showed outstanding rates of climb. The only serious concern was the extremely long landing gear needed to keep the huge 2-bladed prop clear of the ground.
[[File:Siemens-Schuckert D.II - Ray Wagner Collection Image (21439705645).jpg|thumb|D.IIe undergoing stress testing]]
==D.III==
Three more prototypes were ordered, one  D.IIe, with the original sized wings, and two D.IIc's, fitted with shorter and longer span wings. After completion in October 1917, the design proved promising and in December an order for twenty long-span D.IIc's was placed with a smaller 4-bladed propeller that allowed for shorter landing gear legs. Deliveries of these aircraft, now known as D.III, began in January and were followed by an additional order for thirty in February.
All fifty were delivered to front-line units in May, where they proved popular but after only 10 hours of service the engines started showing serious problems, overheating and seizing. Siemens blamed the problem on the Voltol-based oil that was used to replace scarce [[castor oil]] for lubricating the engine but the type was withdrawn from service and replaced by [[Fokker D.VII]]s. When they were removed, [[Rudolf Berthold]], commander of JG.II, noted that he wished "the Siemens fighter be made available again for front-line use as quickly as possible for, after elimination of the present faults, it is likely to become one of our most useful fighter aircraft".{{Citation needed |date=March 2021}}
A version of the Sh.III passed a 40-hour endurance test in June and the aircraft were cleared to return to service in July. In the meantime they had been upgraded with the addition of a new rudder, balanced ailerons and had the cowling cut-away for improved cooling. Some sources also claim that the original engines were replaced with the improved {{cvt|200|PS|kW hp}} Sh.IIIa engines. Another thirty new aircraft with these features were built and all eighty of the improved design entered service in home defense units where their climb rate made them excellent [[interceptor aircraft|interceptor]]s.
==D.IV==
The short-span D.IIc prototype had been further refined and with a narrower {{cvt|1.00|m}} [[Chord (aeronautics)|chord]] upper and lower wing, using the Göttingen 180 airfoil. One wing was slightly longer than the other to counter the [[P-factor]] of its huge four-blade propeller. The port panels outboard of the struts were {{cvt|1110|mm}} in length, while those on the starboard side were {{cvt|1040|mm}} long.<ref>{{cite magazine |author=<!--Staff writer(s); no by-line.--> |title=The Siemens Type D IV Single-Seater Fighter |url=https://www.flightglobal.com/pdfarchive/view/1919/1919%20-%200333.html |magazine=Flight |date=March 13, 1919 |page=333 |access-date=May 5, 2019 }}</ref> The performance improved noticeably in top speed and in climb rate over the D.III. An order for this model, now known as the D.IV, was placed in March 1918 and additional orders were placed as the qualities of the design became known. Aircraft started reaching operational units in August but of the 280 ordered only 123 were completed by the end of the war, about half of those reaching operational units.
Although the short landing gear and limited prop clearance led to tricky landing, the plane was otherwise easy to fly. It had a very short take-off run and at heights above {{cvt|4000|m}} was faster and more manoeuvrable than the Mercedes-powered [[Fokker D.VII]]. Its most notable feature was its phenomenal rate of climb and extremely high service ceiling—it could reach {{cvt|6000|m}} in under 14{{frac|1|2}} minutes. In 36 minutes it could reach {{cvt|8100|m}}, about {{cvt|1200|m}} higher than the ceiling of the Fokker. Production of the D.IV continued after the cease-fire, while one example escaped to [[Switzerland]] where it operated from 1918 to 1922, and another was acquired by the Lithuanians, however it never flew in their service. One examples was used by the Belgians, being marked with the race number 22. With the signing of the [[Treaty of Versailles]] aircraft production in Germany was outlawed and the aircraft division of SSW disappeared. Siemens-Halske later reorganized into [[Bramo]].
==D.V==
In May/June 1918 a sesquiplane, two bay derivative, the '''D.V''' participated in the Adlershof trials. Three were built.<ref>Gray & Thetford, p.563</ref>
==Operators==
;{{BEL}}
*[[Belgian Air Force]] - operated 1 ex-Luftstreitkräfte D.IV from 1919 to 1921
;{{flag|German Empire}}
*''[[Luftstreitkräfte]]''
*''[[Kaiserliche Marine]]''
;{{LTU}}
*[[Lithuanian Air Force]] - received 1 D.IV (No. 6177); however, it never flew in Lithuanian service.<ref>G. Ramoška, Pirmieji karo aviacijos lėktuvai 1919-23 m., http://www.plienosparnai.lt/page.php?81</ref>
;{{SWI}}
*[[Swiss Air Force]] - operated 1 ex-Luftstreitkräfte D.III from 1918 to 1922.
==Specifications (D.IV)==
{{Aircraft specs
|ref= ''German Aircraft of the First World War'' <ref>Gray and Thetford 1962, pp. 216–217.</ref>
|prime units?=met
<!--
General characteristics
-->
|crew=1
|length m=5.7
|length note=
|span m=8.35
|span note=
|height m=2.72
|height note=
|wing area sqm=15.1
|wing area note=
|aspect ratio=<!-- sailplanes -->
|airfoil=Göttingen 180
|empty weight kg=540
|empty weight note=
|gross weight kg=735
|gross weight note=
|max takeoff weight kg=
|max takeoff weight note=
|fuel capacity=
|more general=
<!--
Powerplant
-->
|eng1 number=1
|eng1 name=[[Siemens-Halske Sh.III]]
|eng1 type=11-cylinder air-cooled geared rotary piston engine
|eng1 kw=<!-- prop engines -->
|eng1 hp=<!-- prop engines -->
|eng1 shp=<!-- prop engines -->
|eng1 kn=<!-- jet/rocket engines -->
|eng1 lbf=<!-- jet/rocket engines -->
|eng1 note={{cvt|160|PS|hp kW|1}}
|prop blade number=4
|prop name=fixed-pitch wooden propeller
|prop dia m=<!-- propeller aircraft -->
|prop dia note=
<!--
Performance
-->
|max speed kmh=190
|max speed note=
|cruise speed kmh=
|cruise speed note=
|stall speed kmh=
|stall speed note=
|never exceed speed kmh=
|never exceed speed note=
|range km=380
|range note=
|combat range km=
|combat range note=
|ferry range km=
|ferry range note=
|endurance=2 hours
|ceiling m=8000
|ceiling note=
|g limits=<!-- aerobatic -->
|roll rate=<!-- aerobatic -->
|climb rate ms=
|climb rate note=
|time to altitude=<br/>
::::{{cvt|1000|m}} in 1 minute 54 seconds
::::{{cvt|6000|m}} in 15 minutes 30 seconds
|wing loading kg/m2=48.7
|wing loading note=
|fuel consumption kg/km=
|power/mass={{cvt|0.16|kW/kg}}
|more performance=
<!--
Armament
-->
|guns= 2 × 7.92 mm (0.31 in) [[LMG 08/15]] [[machine gun]]s
}}
==References==
===Notes===
{{Reflist}}
===Bibliography===
* Gray, Peter, and Thetford, Owen. ''German Aircraft of the First World War''. London:Putnam, 1962.
* Munson, Kenneth. ''Aircraft of World War I''. London: Ian Allan, 1967. {{ISBN|0-7110-0356-4}}.
* {{cite book |last=Green |first=William |first2= Gordon|last2= Swanborough |title=The Complete Book of Fighters |date=1994|publisher=Salamander Books|location=Godalming, UK|isbn=1-85833-777-1}}
==External links==
{{Commons category|Siemens-Schuckert D.IV}}
*{{cite journal |date=March 13, 1919 |title=The Siemens Type D IV Single-Seater Fighter |format=PDF |journal=[[Flight (magazine)|Flight]] |volume=XI |issue=11 |id=No. 533 |pages=332–339 |url=http://www.flightglobal.com/pdfarchive/view/1919/1919%20-%200332.html |accessdate=January 12, 2011 }} Contemporary technical description with photographs and drawings, translated from the German aviation journal ''Flugsport''.
{{Siemens-Schuckert aircraft}}
{{Idflieg fighter designations}}
{{World War I Aircraft of the Central Powers}}
{{Authority control}}
[[Category:1910s German fighter aircraft]]
[[Category:Siemens-Schuckert aircraft|D.IV]]
[[Category:Single-engined tractor aircraft]]
[[Category:Biplanes]]
[[Category:Aircraft first flown in 1918]]
[[Category:Rotary-engined aircraft]]
[[ja:ジーメンス・シュッケルト D.III]]