The First Flight Of The Junkers J.I

In January 1917, the Junkers J.I made its first flight and quickly stood out as one of the most technically forward military aircraft of World War I.

Designed as an armored aircraft for ground attack missions and battlefield liaison work, it introduced an all-metal structure paired with unusually strong crew protection. That combination set a new benchmark for durability in frontline aviation and influenced how military aircraft designers thought about survivability for decades afterward.

The first flight took place on January 28, 1917. In internal company documentation at Junkers, the aircraft was designated J 4. In German service, it became known as the Junkers J.I, a World War I-era J-class sesquiplane.

The J class designation was introduced in Germany in 1917 for armored, dual-purpose aircraft intended for both communication duties and ground-attack missions.

An Armored Aircraft Built for Low-Altitude Combat

The Junkers J.I was developed specifically for low-altitude operations, including ground attack, observation, and cooperation with German army units. Those missions exposed crews to intense small arms fire from below, so armor protection became a defining feature of the design.

A large, one-piece steel structure ran from behind the propeller area back to the rear crew position. Often described as a “bathtub,” this armored shell protected both the aircraft’s vital areas and its crew. The engine cowling also received additional protection of the same thickness, listed as 5 mm, which is about 0.2 inches.

Fuel tanks and radio equipment were also protected, reflecting the aircraft’s battlefield liaison role, where communication and endurance mattered as much as firepower.

Rugged Flight Controls For A Dangerous Job

Another notable engineering choice was the way the controls were operated. Instead of the steel cables and pulleys common at the time, the Junkers J.I used pushrods and bell crank mechanisms to transmit control inputs. The intent was greater durability and resilience in combat, since rigid linkages could be less vulnerable to damage from ground fire than cable-driven systems.

A Sesquiplane Wing Layout And Modest Power

The aircraft’s wing design clearly reflected its sesquiplane configuration, with a much larger upper wing than lower wing. The upper wing area was listed at 35.89 square meters, which converts to about 386.3 square feet. The lower wing area was 13.68 square meters, or about 147.3 square feet. This large difference was typical of sesquiplane layouts, which sought to balance lift and structural needs while keeping weight and drag under control.

Power came from a Benz Bz.IV engine rated at 200 horsepower. With that setup, the Junkers J.I reached a maximum speed of about 97 mph.

Operational figures included a range of roughly 193.3 miles and a service ceiling of about 13,000 feet. Those numbers underline the aircraft’s priorities. It was built to survive and work close to the front, not to chase faster fighters at high altitude.

Armament, Service History, And The One Survivor

Armament typically consisted of one flexible 7.92 mm Parabellum MG14 machine gun for the rear crew member, although some accounts mention additional guns on certain aircraft.

The Junkers J.I primarily served on the Western Front, including during the German Spring Offensive in 1918. From 1917 through the end of World War I, Junkers produced a total of 227 J.I. aircraft.

Only one original airframe is known to survive today, marked with the German military designation J.I 586/18. Built in 1918, it was sent to Canada in 1919 as a war trophy. The Canadian War Museum preserved the aircraft until 1969, when it was transferred to the Canada Aviation and Space Museum. The J.I 586/18 is currently on display at that museum in Ottawa, Ontario.

In addition to the surviving original, a flyable replica of the Junkers J. It has been reported as under construction in Hungary.

This article originally appeared on Autorepublika.com and has been republished with permission by Guessing Headlights. AI-assisted translation was used, followed by human editing and review.

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