LFG Roland D.XV

The LFG Roland D.XV was a World War I German single seat fighter aircraft, ordered as a test-bed for engine comparisons. It was distinguished from earlier Roland biplane designs by the elimination of flying wires. Two later aircraft, also called LFG Roland D.XV, were completely different designs closely related to the Fokker D.VII.

The first D.XV version
The D.XV was the last LFG design to use the Klinkerrumpfe (clinker built fuselage) structure, which produced a round cross section fuselage with thin, overlapping, longitudinal spruce strips supported by a light wooden frame, used on a succession of fighter types beginning with the D.IV. Its wings had constant chord and blunt tips, mounted with more stagger than on their earlier designs. The D.XV was a single bay biplane with a lower wing of shorter span than the upper, so the parallel interplane struts leaned outwards; unusually, there were no bracing wires (wireless cellule). The second prototype differed in having a broader chord, slightly greater span upper wing and narrower chord lower planes. The larger upper wing had a trailing edge cut-out to enhance vision from the cockpit, a feature absent from the first aircraft. A single I interplane strut on each side, broadly faired to the wings at top and bottom, replaced the earlier parallel pairs. Only the upper wings carried ailerons.

Initially both prototypes of the D.XV were powered by 160 hp Mercedes D.IIIa six cylinder in-line engines, mounted with the tops of the cylinders just exposed. This unit was later exchanged on the second prototype for a 185 hp BMW IIIa on the same type, mounted within a more circular cross section, slender nose but with more of the cylinders visible. At the rear the tailplane was mounted at mid-fuselage. The vertical tail was ovoid, with a broad, balanced rudder that extended down to a sizeable ventral fin which also carried a tailskid. The main fixed, conventional undercarriage had wheels on a single axle, mounted to the fuselage by V-struts.

The first prototype flew before the end of April 1918 but came back to the factory for modifications the following month. The second flew that June. In September the Idflieg, who had originally requested three D.XVs, called for further alterations in response to their flight testing. The company responded with two examples of a completely different design, whilst retaining the D.XV designation.

The second D.XV version
Aircraft historians have noted the similarity of these designs to the successful Fokker D.VII; some have claimed that it was no more than an unofficial copy, others have seen it as "no slavish copy", with obvious differences in the rear fuselage and empennage design. It was an unequal span, single bay biplane, with constant chord, unswept wings separated by N-form interplane struts, though the cabane structure include a pair of tubular steel parallel struts on each side which leaned outwards from the lower wing root. There were overhung ailerons on the upper wing only.

The third D.XV, the first of this new design, flew in late October 1918 powered by a 185 hp BMW IIIa and the fourth, which flew slightly later by a 200 hp version of that engine. Apart from the engines the two aircraft were very similar, with a plywood covered, rectangular cross-section fuselage tapering strongly in elevation to the tail. The tailplane, mounted on top of the fuselage, carried a one-piece, overhung elevator. The fin carried a rounded, balanced rudder smoothly profiled with it, which bottomed well above the elevator. Its undercarriage was similar to that of the first D.XVs.

The development of these aircraft was terminated by the Armistice that November.