Engineering:Dornier Komet

Komet, Merkur, and related
Komet III
Role	Airliner
Manufacturer	Dornier Flugzeugwerke
First flight	1921
Developed from	Dornier Delphin
Variants	Dornier Do 10

The Dornier Komet ("Comet"), Merkur ("Mercury"), Do C, Do D, and Do T were a family of aircraft manufactured in Germany during the 1920s, originally as small airliners, but which saw military use as well. The earliest aircraft in the series were basically landplane versions of the Delphin flying boat, and although the Delphin and Komet/Merkur series diverged from each other, design changes and refinements from one family were often incorporated into the other. All variants were braced high-winged single-engine monoplanes with conventional landing gear.

Design and development

Dornier Komet

Dornier Komet II (2), 1922

A version of the Dornier Komet at Dübendorf airfield

The first Komets (Do C III Komet I) utilised the same rectangular plan, 17 m (55 ft 9 in) span wing, tail, and even upper fuselage, as well as the 138 kW (185 hp) BMW IIIa engine of the Delphin I, but replaced the lower fuselage and sponsons with a simple sheet-metal bottom that incorporated fixed tailskid undercarriage. The engine installation was also relocated from above the Delphin's nose to a conventional location in the Komet's fuselage nose. Accommodation was provided for a single pilot and four passengers. An improved version, the Do Komet II, was first flown on 9 October 1922 and was widely exported to countries including Colombia, Spain, Switzerland, and the Soviet Union.

The Do Komet III of 1924 was a practically all-new design that shared many elements with the Delphin III. The cabin was expanded to seat another two passengers and the larger wing, with a span of 19.6 m (64 ft 4 in), was raised above the fuselage on short struts. Power was greatly increased from the Komet I, with a 340 kW (450 hp) Napier Lion engine. This version was exported to Denmark and Sweden, but was also produced under licence in Japan by Kawasaki.

In 1925, the Komet III was replaced in production by the Do B Merkur I, which featured a revised fin and longer-span wings. When fitted with the BMW VI engine, it became known as the Do B Bal Merkur II, as did indeed any Komets thus re-engined. The type was widely used by Deutsche Luft Hansa, which had some 30 Merkurs operating at one time, and was also exported to Brazil, China, Colombia, Japan, and Switzerland.

The Do C and Do D were follow-on military designs, the former a trainer exported to Chile and Colombia, the latter a floatplane torpedo-bomber built for the Yugoslav Royal Navy. The designation Do T was used for a landplane ambulance version.

A replica Dornier Merkur was made for the Dorner Museum in the early 2000s.

Variants

Dornier Do D seaplane version, from L'Aérophile December,1927

Dornier Merkur ambulance version

First of the Komet series

Do Komet II

Do Komet III

larger, more powerful four-six passenger version.

Do B Merkur I

Do B Bal Merkur II

Do C

Military version of the Komet III

• Do C-1: Two-seat fighter.
• Do C-2A: Recognition version.
• Do C-3: Recognition version.
• Do C-4: Do-10, development of C-1.

Do D

A much revised floatplane torpedo bomber version for the Royal Yugoslav Air Force

Do T

An ambulance version

Operators

Civil operators

Dornier B-Bal "Merkur" of Ad Astra Aero S.-A.

Dornier Merkur (CH 142) operated by Ad Astra Aero (1927)

Colombia

• SCADTA

Germany

• Deutsche Luft Hansa
• Deutsche Luft-Reederei

Switzerland

• Ad Astra Aero

Ukraine

• Ukrvozdukhput

Soviet Union

• Deruluft
• Dobrolyot

Military operators

Chile

• Chilean Air Force
• Chilean Navy

Colombia

• Colombian Air Force

Kingdom of Yugoslavia

• Yugoslav Royal Navy

Specifications (Merkur II)

Dornier Merkur 3-view drawing from NACA Aircraft Circular No.30

Dornier Merkur replica on display

Dornier Merkur (side view)

Front view

Interior view of the Merkur on display at the Dornier Museum

Data from European Transport Aircraft since 1910

General characteristics

• Crew: one
• Capacity: eight passengers
• Length: 12.5 m (41 ft 0 in)
• Wingspan: 19.6 m (64 ft 4 in)
• Height: 3.56 m (11 ft 8 in)
• Wing area: 62.0 m² (667 sq ft)
• Empty weight: 2,100 kg (4,630 lb)
• Gross weight: 3,600 kg (7,937 lb)
• Powerplant: 1 × BMW VI water-cooled V-12 engine, 450 kW (600 hp)

Performance

• Maximum speed: 200 km/h (120 mph, 110 kn)
• Cruise speed: 180 km/h (110 mph, 97 kn)
• Range: 750 km (466 mi, 405 nmi)
• Service ceiling: 5,200 m (17,100 ft)

Bibliography

• Cooksley, Peter (September–October 1996). "Celestial Coaches: Dornier's Record Breaking Komet and Merkur". Air Enthusiast (65): 20–24. ISSN 0143-5450. 
• Donald, David, ed (1997). The Encyclopedia of World Aircraft. Leicester, UK: Blitz Editions. ISBN 1-85605-375-X. 
• Hooks, Mike (June 2016). "Dornier Rising". Aeroplane 44 (5): 48–53. ISSN 0143-7240. 
• Isaic, Vladimir (March–April 1999). "Yugoslav Naval Strike: Dornier's Merkur Seaplane in the Military Role". Air Enthusiast (80): 72–75. ISSN 0143-5450. 
• Ledet, Michel (April 1993). "L'aéronautique naval yugoslave des années 20 à Avril 1941" (in French). Avions: Toute l'aéronautique et son histoire (2): 2–12. ISSN 1243-8650. 
• Nikolic, Djordie; Ognjevic, Akeksandar M. (2021). Dornier: The Yugoslav Saga 1926-2007. Lublin, Poland: Kagero Publishing. ISBN 978-83-66673-61-8. 
• Stroud, John (1966). European Transport Aircraft since 1910. London: Putnam. 
• Stroud, John (January 1984). "Wings of Peace—Part 4: Dornier Komet and Merkur". Aeroplane Monthly 12 (1): 34–39. ISSN 0143-7240. 
• Tassell, Roy (May–June 1999). "Round-Out". Air Enthusiast (81): 78. ISSN 0143-5450. 

Further reading

• Taylor, Michael J. H. (1989). Jane's Encyclopedia of Aviation. London: Studio Editions. pp. 327. 
• World Aircraft Information Files. London: Bright Star Publishing. pp. File 892 Sheet 26. 

External links

• German aircraft between 1919 and 1945