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.
(OPERATORS list includes past, present, and future operators when applicable)
✓Intelligence-Surveillance-Reconnaissance (ISR), Scout
Surveil ground targets / target areas to assess environmental threat levels, enemy strength, or enemy movement.
Design incorporates rear-facing pusher-prop arrangement, a contrast to the more conventional puller-prop layout.
Addition of more mainplanes to enhance inherent agility, providing a tactical edge in tight engagements.
Inherent ability of airframe to take considerable damage.
Can reach and operate at higher altitudes than average aircraft of its time.
EXTENDED RANGE PERFORMANCE
Capability to travel considerable distances through onboard fuel stores.
Manual process of allowing its pilot and / or crew to exit in the event of an airborne emergency.
Beyond a pilot, the aircraft takes advantage of additional crew specialized in specific functions aboard the aircraft.
Defensive gun positions for engagement / suppression.
28.9 ft (8.82 m)
42.0 ft (12.80 m)
9.8 ft (3.00 m)
1,653 lb (750 kg)
2,480 lb (1,125 kg)
+827 lb (+375 kg)
(Showcased structural values pertain to the base Hafeli DH-1 production variant)
biplane / over-under / straight
Design utilizes a dual-plane wing arrangement in which one mainplane member is seated above the other; biplanes enhance agility at the expense of added drag.
Dual mainplane configuration seating the members in an over-under fashion and poisitoned at different points along the fuselage.
The planform involves use of basic, straight mainplane members.
(Structural descriptors pertains to the base Hafeli DH-1 production variant)
1 x Argus As II 6-cylinder, water-cooled inline piston engine developing 120 horsepower driving two-bladed wooden propeller in pusher arrangement.
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