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Hafeli DH-1

Twin-Boom Reconnaissance Biplane

Switzerland | 1916

"The Hafeli DH-1 was the beginning of a line of reconnaissance-minded aerial platforms for the Swiss Air Force appearing during World War 1."

Authored By: Staff Writer | Last Edited: 09/13/2021 | Content ©www.MilitaryFactory.com | The following text is exclusive to this site; No A.I. was used in the generation of this content.
Swiss aeronautical engineer August Hafeli helped the German aero-concern of AGO Flugzeugwerke realize their C.I and C.II reconnaissance-minded biplanes in 1915 as World War 1 (1914-1918) raged across Europe. That same year, Eidgenoessische Konstruktionswerkstaette (K+W) was established in Switzerland and Hafeli was hired on to complete a similar project for the Swiss Air Force - beginning with the twin-boom "DH-1". This aircraft then spawned a series of similar designs for the country that included the DH-2 of 1916, DH-3 of 1917, and DH-4 of 1918 - these featuring a more conventional in-line design arrangement.

The DH-1 biplane would have reconnaissance as its central role and utilize a proven over-under biplane wing arrangement featuring three bays. Wood and fabric were used throughout its construction. The crewspace involved open-air cockpits seated along a centralized nacelle with booms stretching rearwards with each component capped by a small-area, rounded rudder plane. The booms were joined by a shared horizontal plane. The twin-wheeled undercarriage was fixed under the center mass with a basic skid added to the tail section for ground-running. The engine was installed at the aft-end of the fuselage component, completing the design arrangement of this aircraft. It carried a single machine gun of 7.45mm caliber for self-defense.

By and large, the DH-1 was similar in both form and function to Hafeli's earlier designs for AGO - highly conventional and no-nonsense.

The aircraft was powered by a single Argus As II series 6-xylinder, inline liquid-cooled piston engine outputting 120 horsepower and used to spin a two-bladed (fixed-pitch) wooden propeller. This powerplant was locally-built under license by Buhler Brothers Ltd. Since its placement was at the rear of the fuselage nacelle, the propeller arranged in a "pusher" configuration - this cleared the frontal vision and firing arcs of the aircraft for the observation crew.

Dimensions of the biplane included a running length of 28.10 feet, a wingspan of 42 feet, and a height of 9.9 feet. Performance included a maximum speed of 78 miles-per-hour, a range out to 160 miles, and a service ceiling of 32,280 feet.

Following a first-flight of the prototype, series introduction followed as soon as 1916 and the aircraft was in active use until 1919 with the Swiss Air Force. Only six were produced in all and no examples were exported. The survivors were eventually scrapped.

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Power & Performance
Those special qualities that separate one aircraft design from another. Performance specifications presented assume optimal operating conditions for the Hafeli DH-1 Twin-Boom Reconnaissance Biplane.
1 x Argus As II 6-cylinder, water-cooled inline piston engine developing 120 horsepower driving two-bladed wooden propeller in pusher arrangement.
78 mph
125 kph | 67 kts
Max Speed
65 mph
105 kph | 57 kts
Cruise Speed
32,283 ft
9,840 m | 6 miles
Service Ceiling
155 miles
250 km | 135 nm
Operational Range
City-to-City Ranges
Operational range when compared to distances between major cities (in KM).
The nose-to-tail, wingtip-to-wingtip physical qualities of the Hafeli DH-1 Twin-Boom Reconnaissance Biplane.
28.9 ft
8.82 m
O/A Length
42.0 ft
(12.80 m)
O/A Width
9.8 ft
(3.00 m)
O/A Height
1,653 lb
(750 kg)
Empty Weight
2,480 lb
(1,125 kg)
Design Balance
The three qualities reflected below are altitude, speed, and range. The more full the box, the more balanced the design.
Available supported armament and special-mission equipment featured in the design of the Hafeli DH-1 Twin-Boom Reconnaissance Biplane .
1 x 7.45mm machine gun on trainable mounting in forward cockpit (managed by the observer).
Notable series variants as part of the Hafeli DH-1 family line.
Global customers who have evaluated and/or operated the Hafeli DH-1. Nations are displayed by flag, each linked to their respective national aircraft listing.

Total Production: 6 Units

Contractor(s): Eidgenossische Konstruktionswerkstaette (K+W) / Hafeli - Swtizerland
National flag of Switzerland

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Image of the Hafeli DH-1
Image from the Swiss Federal Archives; Public Domain.

Developments of similar form-and-function, or related, to the Hafeli DH-1 Twin-Boom Reconnaissance Biplane.
Going Further...
The Hafeli DH-1 Twin-Boom Reconnaissance Biplane appears in the following collections:
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