Häfeli DH-3
{{Infobox aircraft
|name = DH-3
|image = Der Doppeldecker wird in Position geschoben - CH-BAR - 3239658.tif
|caption =
|type = Reconnaissance biplane
|manufacturer = K+W
|designer = August Häfeli
|first_flight =
|introduction = 1917
|retired = 1939
|status =
|primary_user = Swiss Air Force
|more_users =
|produced =
|number_built = DH-3 24
DH-3a 83
DH-3b 3
|unit cost =
|developed_from = Hafeli DH-2
|variants =
}}
The Häfeli DH-3 was a 1910 Swiss two-seat reconnaissance aircraft, built by the aircraft department of the Federal Construction Works (Eidgenoessische Konstruktionswerkstaette, (K+W)) at Thun, Switzerland.
Development and design
Following the poor performance of the DH-2, August Häfeli designed an improved version the Häfeli DH-3. It was basically the same airframe as the DH-2, the upper wing had a cutout to give a greater field of fire for the pivoting machine gun.
It was a two-bay aircraft of wood and fabric construction, powered by a 120 hp (89 kW) Argus As II water-cooled inline engine. Initial problems with the landing gear and the engine cooling system led to modifications. Further developments were the re-engined and improved DH-3a, and the DH-3b used for engine trials. Following successful trials with an installation of the Handley Page slats all surviving DH-3as were modified in 1932.
Operational history
On 8 January 1919 a DH-3 inaugurated the first Swiss air mail service between Zurich and Berne. A DH-3 aircraft failed a structural test in 1923 which caused the DH-3 to be withdrawn from service. The DH-3a, following modification, remained in service until 1939.
Variants
;DH-3
:Initial production version with Argus As II engine, 24 built.
;DH-3a
:Improved version with Hispano-Suiza HS-41 8Aa engines, four aircraft ordered in 1919. A second order for 30 aircraft was placed in 1919 with license-built engines, a third order for 49 aircraft being placed in 1925. Survivors were modified at Thun in 1932 with Handley Page slats and changes to allow crew to wear parachutes.
;DH-3b
:Three aircraft powered by the indigenous 150 hp (112 kW) LFW 0 engine developed by the Swiss Locomotive and Machine Works were built in 1918.
Operators
Specifications (DH-3a)
{{Aircraft specs
|ref=The Illustrated Encyclopedia of Aircraft (Part Work 1982–1985){{cite book |title= The Illustrated Encyclopedia of Aircraft (Part Work 1982–1985)|publisher= Orbis Publishing}}
|prime units?=met
|crew=2
|length m=7.95
|span m=12.5
|upper span m=
|mid span m=
|lower span m=
|width m=
|height m=3.1
|wing area sqm=38
|aspect ratio=
|airfoil=
|empty weight kg=1587
|gross weight kg=1110
|max takeoff weight kg=
|fuel capacity=
|more general=
|eng1 number=1
|eng1 name=Hispano-Suiza 8Aa (HS-41)
|eng1 type=V-8 water-cooled piston engine
|eng1 hp=150
|prop blade number=2
|prop name=fixed-pitch propeller
|prop dia m=
|prop dia ft=
|prop dia in=
|prop dia note=
|max speed kmh=145
|max speed mach=
|cruise speed kmh=
|stall speed kmh=
|never exceed speed kmh=
|minimum control speed kmh=
|range km=400
|combat range km=
|ferry range km=
|endurance=
|ceiling m=4500
|g limits=
|roll rate=
|climb rate ms=
|time to altitude=
|wing loading kg/m2=
|fuel consumption kg/km=
|power/mass=
|more performance=
|guns= 1x flexible machine gun in the rear cockpit
|bombs=
}}
References
{{reflist}}
External links
{{commons category|Häfeli DH-3}}
- ETH-Bibliothek Zürich, Bildarchiv. [http://doi.org/10.3932/ethz-a-000021315 Häfeli DH-3 (M III) No 530, Argus As II engine], [http://viewer.e-pics.ethz.ch/ETHBIB.Bildarchiv/index2.php?id=ETHBIB.Bildarchiv_Ans_03716-FL viewer]
- ETH-Bibliothek Zürich, Bildarchiv. [http://doi.org/10.3932/ethz-a-000031687 Häfeli DH-3 M IIIb, Argus As II engine], [http://viewer.e-pics.ethz.ch/ETHBIB.Bildarchiv/index2.php?id=ETHBIB.Bildarchiv_Ans_05035-090 viewer]
- ETH-Bibliothek Zürich, Bildarchiv. [http://doi.org/10.3932/ethz-a-000031857 Häfeli DH-3 aircraft, Argus As II engine], [http://viewer.e-pics.ethz.ch/ETHBIB.Bildarchiv/index2.php?id=ETHBIB.Bildarchiv_Ans_05035-163 viewer]
- [https://web.archive.org/web/20110706222659/http://thunensis.braindesign.ch/index.php?option=com_ponygallery&Itemid=26&func=viewcategory&catid=33 Konstruktion Häfeli DH-3 in Thun]
{{DEFAULTSORT:Hafeli Dh-3}}
Category:1910s Swiss military reconnaissance aircraft