Aviatik (Berg) D.I

The Aviatik D.I, was a single-engine, single-seater fighter biplane. It was also known as Berg D.I or the Berg Fighter because it was designed by Dipl. Ing. Julius von Berg. The D.I was the first indigenously designed fighter aircraft of the Austro-Hungarian Air Service (Luftfahrtruppen).

Development
Work on the prototype began in August 1916, while the first flight of the Aviatik D.I prototype, marked 30.14, took place at 16 October 1916 at Aspern, unfortunately killing the test pilot.

Further modifications were made, and three more prototypes of the Aviatik D.I were manufactured, labeled 30.19 (for tests on the ground), 30.20 (for tests in flight) and 30.21 (as a reserve airframe). These prototypes differed from the production aircraft in having a single unsynchronized Schwarzlose machine gun above the top wing, firing over the propeller.

Tests of the modified aircraft were positive and the first unit to receive the first serial batch (with two synchronized Schwarzloses, one on each side of the cylinder block) of the Aviatik D.I was Fluggeschwader I (FLG I, later to be renamed to Flik 101G) on the Divača airfield in Slovenia.

Production
The Aviatik D.I was manufactured under license by a numbers of subcontractors.


 * Austrian Aviatik built the 38, 138, 238 and 338 Series
 * Lohner built the 115 and 315 Series
 * Lloyd manufactured the 48, 248 and 348 Series.
 * MAG (Magyar Általános Gépgyár - General Hungarian Machine Works) built the 84 and 92 Series
 * Thöne und Fiala manufactured the 101 Series
 * WKF (Wiener Karosserie Fabrik - Vienna (Car)Body Factory built the 184, 284 and 384 Series.

Ordered but not build were the 215 and 201 Series from Lohner and Thöne und Fiala respectively.

The main differences between the Series were in the power of Austro-Daimler engines used (185 hp in the early production aircraft, 200 or 210 hp in the mid-production, and 225 hp in the last ones), in exact positioning of the machine guns, and in structural and radiator modifications.

Until the 31st October 1918 a number of 677 Aviatik D.I airframes of all batches were handed over to the Austro-Hungarian Air Force.

Operational service
In many respects, the D.I was a good combat aircraft. It was reasonably fast, had excellent flying characteristics and maneuverability, and could reach higher altitudes than most of its adversaries. In addition, it was provided with a roomy and comfortable cockpit which gave a good field of view.

Despite those desirable features, the new Aviatik fighter wasn't greeted with enthusiasm when it entered service in autumn 1917, as the type also had some serious defects which didn't endear it to its pilots. The early aircraft had structural deficiencies and their machine guns were installed beyond the reach of the pilot; if the gun(s) jammed, there was nothing he could do about it. These problems were later rectified with the strengthening of the airframe and the repositioning of the guns. While the original Aviatik D-I design by Julius von Berg was sound, the Series 115 aircraft license-produced by the Lohner firm at Wien-Floridsdorf were notorious for failures along the wing trailing edges in high speed maneuvers, as Lohner had deviated from Aviatik specifications by employing thinner, lighter wing ribs. The main cause of complaints was the engine's tendency to overheat far too easily. To alleviate these cooling problems, operational units tended to fly their aircraft without the engine's top panels and sometimes also the side panels were left off.

The Austro-Hungarian aviation units used the D.I widely until the end of World War I on Eastern, Italian and Balkan fronts, mainly as an escort fighter for the 2-seater reconnaissance aircraft, as the most fighter units preferred the Albatros D.III in air superiority role.

Variants
The D.II was a version of the D.I with a cantilever lower wing. The model went into production in late 1918 in two Series (39 and 339), but the production aircraft were too late for operational service. The D.III high-altitude version with a 230 hp Hiero engine and the Dr.I triplane development remained as prototypes only.

Operators

 * Austria-Hungary
 * Austro-Hungarian Imperial and Royal Aviation Troops
 * Austro-Hungarian Navy
 * Royal Romanian Air Force - Postwar.
 * Kingdom of Yugoslavia
 * Royal Yugoslav Air Force - Postwar.
 * Royal Yugoslav Air Force - Postwar.