Hafeli DH-4 (M.IV)

History of the Hafeli DH-4 (M. IV)

Swiss engineer August Hafeli contributed to military aircraft development for the Swiss Air Force, influenced by his previous work absorbed by the A.G.O. German Empire. His designs, such as the "DH-1," were inspired by German biplanes and aimed to bolster Switzerland's aviation capabilities.

The transition to the "DH-2" marked a shift from a dual-arm configuration to a simpler inline design. This evolution culminated in the successful production of the "DH-3" in 1917, a reconnaissance aircraft armed with a single machine gun, totaling 110 units manufactured. However, Hafeli's endeavors during World War I didn't stop there.

In 1918, Hafeli's team introduced the "DH-4," a combat-focused biplane intended to build upon the DH-3's achievements. Despite its promise, the DH-4 faced challenges during testing, failing to meet performance expectations despite modifications. Its top speed reached 92 mph, with a range of 190 miles and a climb rate of 890 feet per minute, but ultimately, it fell short of its intended role.

Specification

Basics

Year of Service: 1918

Origins: Switzerland

Status: Development ended.

Crew: 1

Production: 1

Manufacturer: Swiss Federal Design Studio (K+W) / Hafeli - Switzerland

Roles

Air-to-air combat, fighter: The general ability to actively attack other aircraft of similar form and function, usually using guns, missiles and/or airborne missiles.

X-Plane (development, prototype, tech demo): Aircraft designed for prototyping, technology demonstration, or research/data collection.

Notable Features

Sync/Interrupt Gear: The automatic weapons are synchronized through a special mechanical gear assembly and fired by rotating propeller blades.

Leafy: Added more main aircraft to improve inherent agility and provide tactical advantage in close combat.

Sturdy aircraft frame: The inherent ability of the airframe to take significant damage.

High-speed performance: Can accelerate to higher speeds than the average aircraft at the time.

Extended range performance: Ability to travel long distances using on-board fuel supplies.

Dimensions and Weight

Length: 19.7 feet (6.00 m)

Width/span: 32. 2 feet (9.80 m)

Height: 8.5 feet (2.60 m)

Cured weight: 1,433 lbs (650 kg)

MTOW: 1,951 lbs (885 kg)

Wgt Difference: +518 lbs (+235 kg)

Main surface structure

Biplane: The design features a biplane wing arrangement with one main plane element on top of the other. Biplanes have improved agility at the expense of increased drag.

Up and down: Two main aircraft configurations where elements are stacked and positioned at different points on the fuselage.

Straight: Floor plans involve the use of simple, straight main plan elements.

Performance

Installed: 1 x Hispano-Suiza HS-41 150hp 8-cylinder in-line liquid-cooled engine driving a two-bladed fixed-pitch wooden propeller in the nose.

Maximum speed: 93 km/h (150 km/h | 81 knots)

Cruising speed: 78 km/h (125 km/h | 67 knots)

Maximum speed difference: +26 km/h (+25 km/h | 13 kn)

Maximum: 14,108 feet (4,300 m | 3 km)

Area: 186 km (300 km | 556 nautical miles)

Rate of climb: 890 ft/min (271 m/min)

Weapon

1 x 7.45mm machine gun, fixed to the nose forward firing bracket, firing synchronously through the rotating propeller blades.