Albatros L 68

Albatros L 68
Albatros L 68a
Type:	Trainer aircraft
Design country:	German Empire
Manufacturer:	Albatross
First flight:	1925
Number of pieces:	18th

The Albatros L 68 is a biplane designed for beginners training aircraft from the 1920s and one of the first types to be developed by the Albatros Flugzeugwerke in Berlin-Johannisthal , which was founded in early 1925 .

development

The L 68 was developed in 1925 by Albatros chief designer Rudolf Schubert and flew for the first time that same year. Also in 1925 she won the Sachsen-Rundflug in class C. The first version, of which three copies were built, only had ailerons in the upper wing and therefore in the lower flaps. Schubert revised the design in 1926, increased the span and now also provided the lower wings with ailerons, which were connected to the upper with bumpers. The Siemens motor used was replaced by a more powerful one of the same make. There were also three of this version, known as the L 68a .

In 1927 the L 68 was revised again, albeit only slightly, this time by Walter Blume , who had replaced Schubert as chief designer the previous year. Changes concerned the crossover of the rear main landing gear with wire and a now balanced rudder; the Sh-12 drive was retained. This model, known as the L 68c "Alauda" , was produced in large numbers (10).

In 1928 the model was tested with two different engines: the L 68d received an eleven-cylinder Sh III rotary engine with a four-blade propeller and the L 68e a British Lynx drive. However, both aircraft remained unique.

commitment

The L 68 was mainly used by organizations that were officially civil in character, but secretly carried out the training of military pilots in Germany, which is prohibited by the provisions of the Versailles Treaty . These were the Sportflug GmbH , the Deutsche Luftfahrt GmbH and the Deutsche Verkehrsfliegerschule . The German Aviation Research Institute also used the L 68. In 1926, an aircraft was delivered to the Secret Aviation School and testing facility of the Reichswehr in Lipetsk. The last L 68s flew well into the 1930s.

construction

The L 68 is a single-handled, braced and heavily staggered double-decker in a composite construction with a tail landing gear .

hull

The fabric-covered fuselage frame consists of a welded tubular steel framework, reinforced in the front part with diagonal steel struts and crossed with wire in the rear. The tubular steel motor support, which is clad with aluminum sheets, is fitted with a hinge so that the drive can be folded in to the side for maintenance work. The two separate pilot cabins, one behind the other, are equipped with a double steering wheel that can be disengaged in the student cockpit.

Structure

The wings are made of a wooden frame with two box spars and ribs, which is clad with plywood on the nose edge, planked with plywood on the underside between the spars and otherwise covered with fabric. The three-part upper wing consists of the two outer surfaces and the central piece, designed as a canopy and connected to the fuselage, which also contains the fuel drop tank with a capacity of 100 l. The two-part lower wings are connected directly to the fuselage. The connection with each other is made by N-posts. The bracing runs from the upper rear to the lower front spar.

Tail unit

The normally executed tail unit consists of a tubular steel frame covered with fabric, the horizontal and vertical fin are supported against each other by I-struts. With the exception of the rudder on the L 68c, all rudders are unbalanced. The horizontal stabilizer can be adjusted in flight. With the exception of the basic version, all wings have ailerons, which are connected to each other by bumpers on each side.

landing gear

The rigid main landing gear consists of two main wheels with high pressure tires connected by an axle and attached to V-struts and a steerable tail skid coupled to the rudder.

Technical specifications

Two-sided view

Parameter	Data (L 68)	Data (L 68a)	Data (L 68c)	Data (L 68e)
crew	2
span	9.60 m	10.10 m
length	6.15 m	6.3 m	6.48 m	7.47 m
height	2.50	2.56 m	2.87 m	k. A.
Wing area	21.8 m²	24.4 m²	25.07 m²
V position	above 0 °, below 2 °
Wing loading	32.2 kg / m²	k. A.	34.9 kg / m²	k. A.
Power load	9.37 kg / hp	k. A.	8.75 kg / hp	k. A.
Preparation mass	380 kg	650 kg	595 kg	740 kg
Takeoff mass	640 kg	950 kg	875 kg	1070 kg
drive	an air-cooled seven-cylinder - four stroke - radial engine	an air-cooled nine - cylinder four-stroke radial engine		an air-cooled seven-cylinder four-stroke radial engine
Type	Siemens & Halske Sh 11	Siemens & Halske Sh 12		Armstrong Siddeley Lynx
Starting power	96 hp (71 kW)	125 PS (92 kW)		238 hp (175 kW)
Top speed	130 km / h near the ground	140 km / h near the ground	135 km / h near the ground	185 km / h near the ground
Marching speed	110 km / h		120 km / h	165 km / h
Landing speed	68 km / h	70 km / h		75 km / h
Rise time	12 min at 1000 m		9.16 min at 1000 m 23.42 min at 2000 m	k. A.
Service ceiling	3800 m	4200 m	3500 m	4000 m
Range	approx. 500 km radius of action	360 km		k. A.

literature

• Peter All-Fernandez (ed.): Aircraft from A to Z . Volume 1: Aamsa Quail-Consolidated P2Y. Bernard & Graefe, Koblenz 1987, ISBN 3-7637-5904-2 , p. 80 .
• Helmut Stützer: The German military aircraft 1919–1934 . E. S. Mittler & Sohn, Herford 1984, ISBN 3-8132-0184-8 , p. 102 .

Web links

Commons : Albatros L 68  - Collection of images, videos and audio files

Individual evidence

1. ↑ K. Grasmann (Ed.): Airplane type tables. DMZ 1925-1927 . 1977 (facsimile reprint Deutsche Motor-Zeitschrift, issue 14/1925).
2. ↑ Dieter Stammer: The cradle of the German Air Force in the Soviet Union . In: FLiEGERREVUE X . No. 47 . PPVMedien, 2014, ISSN  2195-1233 , p. 49 .