Aircraft

Dornier Do. F / Do-11 / Do-13

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Do.13

During the late 1920s the German Dornier Metallbauten set up a subsidiary at Altenrhein in Switzerland to build heavy aircraft expressly forbidden under the terms of the Versailles Treaty. The Do P had four engines, the Do Y three, and the Do F was a large twin. All were described as freighters, but their suitability as bombers was obvious. In late 1932 it was boldly decided to put the F into production at the German factory at Friedrichshafen, the designation being changed to Do 11. The Do F, built at Dornier’s Altenrhein factory in Switzerland, and which first flew in May 1932, powered by two 550 hp Siemens built Bristol Jupiter radials and having a retractable main landing gear.
The Do 11 had a slim light-alloy fuselage, high-mounted metal wing with fabric covering carrying two 484.4kW Siemens Sh 22B engines (derived from the Bristol Jupiter), and a quaint retractable landing gear whose vertical main legs were laboriously cranked inwards along the inner wing until the large wheels lay flat inside the nacelles. There was obvious provision for a bomb bay and three gun positions.
In 1933, well before the official establishment of the Luftwaffe, an official order was placed for a production version of the Do F with two 650 hp Siemens Sh 22B 2 nine-cylinder radials, driving three blade wooden propellers. They were delivered from late 1933 as Do 11Cs to the German State Railways which under the cover of a freight service actually enabled the embryo Luftwaffe to begin training future bomber crews. Although they were so used for freight, gun installations, bomb racks and other military items were delivered separately and secretly. Thus they could be converted quickly into bombers and were openly in service as such in early 1934 with the Befeffiskampfgeschwader (auxiliary bomber wing) of the Luftwaffe.
The Do 11C was a twin engined, high wing monoplane, with an all metal fuselage and a glazed observation section in the nose. The crew consisted of a pilot, wireless operator and two gunners, the latter sharing the three single 7.9 mm (0.311 in) MG 15 machine-guns, one each in dorsal and ventral positions and one on a ring mounting forward of the front cockpit.
The Do 11C was a contemporary of the Ju 52/3m in the initial formation of Luftwaffe bomber squadrons.
It had been planned to deliver 372 Do 11 in 1934 but delays, plus grossly unpleasant handling and structural qualities, led to the development of the Do 11D with modified, shorter span wings, and the Do 11Cs in service were also converted to this standard. This was further developed into the Do 13, by fitting non retractable landing gear and doing away with the glazed nose and the small auxiliary horizontal stabilizers fitted under the Do 11’s tailplane.
At least 77 Do 11D were delivered, some later being passed on to another clandestine air force, that of Bulgaria.

The Do 13 was first flown on February 13, 1933, with the same powerplant as its predecessor. Substitution of Junkers type ‘double wing’ trailing edge flaps, similar to those of the Ju 52/3m, gave it improved landing characteristics, and when the Sh 22 engines were replaced by a pair of 750 hp 12¬cylinder liquid cooled BMW VIUs, driving four blade propellers, the bomber was redesignated Do 13C.
The Do 13 with fixed (often spatted) landing gear was wholly unacceptable, but in September 1934 testing began of a completely redesigned machine called Do 13e with stronger airframe, Junkers double-wing flaps and ailerons and many other changes. To erase the reputation of its forbear this was redesignated Do 23 and in March 1935 production restarted of Do 23F bombers.

No attempt was made to disguise the function of the bomber: the fuselage having a glazed nose for visual aiming of the 1,000kg bomb load housed in vertical cells in the fuselage, and nose, mid-upper and rear ventral positions each being provided with a 7.92mm MG 15 machine-gun. After building a small number the Dornier plant switched to the Do 23G with the BMW VIU engine cooled by ethylene-glycol. By late 1935 more than 200 had been delivered and these equipped the first five named Fliegergruppen – although about two-thirds of their strength comprised the distinctly preferable Ju 52/3m. Although it played a major part in the formation of the Luftwaffe and continued to the end of World War II to serve in training, trials and research roles, the Dornier Do 23 was not much better than its disappointing predecessors.

Do 11D
Span: 26.30 m (86 ft 3.5 in)
Length 18.80 m (61 ft 8.25 in)
Gross weight 8200 kg (18078 lb)
Maximum speed: 260 km/h (161 mph).

Do-13
Engine: 2 x BMW VIU, 540kW
Take-off weight: 8750-9200 kg / 19291 – 20283 lb
Empty weight: 3150 kg / 6945 lb
Wingspan: 25.6 m / 83 ft 12 in
Length: 18.8 m / 61 ft 8 in
Height: 5.4 m / 17 ft 9 in
Wing area: 108.0 sq.m / 1162.50 sq ft
Max. Speed: 260 km/h / 162 mph
Cruise speed: 210 km/h / 130 mph
Ceiling: 4000 m / 13100 ft
Range w/max.fuel: 1200 km / 746 miles
Armament: 3 machine-guns, 1000kg of bombs
Crew: 4

Dornier Do-X

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First conceived by Dr. Claudius Dornier in 1924, planning started in late 1925 and after over 240,000 work hours it was completed in June 1929. The Dornier Do X weighed 62 tonnes (61 tons) loaded, spanned 48 m (157 ft), had three decks, carry 100 passengers, and was powered by 12 Siemens built Bristol Jupiter radial engines of 550 hp mounted in tandem pairs atop a forest of struts above its wing. The three decks included a lounge, smoking room, bathroom, kitchen and dining room as well as individual sleeping cabins. Fully loaded, the maximum speed was only 160km/h.

The luxurious passenger accommodation approached the standards of transatlantic liners. On the main deck was a smoking room with its own wet bar, a dining salon, and seating for the 66 passengers which could also be converted to sleeping berths for night flights. Aft of the passenger spaces was an all-electric galley, lavatories, and cargo hold. The cockpit, navigational office, engine control and radio rooms were on the upper deck. The lower deck held fuel tanks and nine watertight compartments, only seven of which were needed to provide full flotation.

The Do X was financed by the German Transport Ministry and built in a specially designed plant at Altenrhein on the Swiss portion of Lake Constance. This, in order to circumvent the Treaty of Versailles which forbade any aircraft exceeding set speed and range limits to be built in Germany after World War I. The Dornier Do X was the largest, heaviest, and most powerful flying boat in the world when it was produced in 1929.

The Do X was built in Switzerland by Aktiengesellschaft fur Dornier-Flugzeuge at Altenrhein, was launched on 12 July 1929, and first flew off the Bodensee on 25 July 1929 with a crew of 14. The Do X is a semi-cantilever monoplane, an all-duralumin hull, with wings composed of a steel-reinforced duralumin framework covered in heavy linen fabric, covered with aluminum paint.

It was initially powered by twelve 391 kW (524 hp) Siemens-built Bristol Jupiter radial engines (six tractor propellers and six pushers), mounted in six tower nacelles on the wing. The nacelles are joined by an auxiliary wing whose purpose was to stabilize the mountings. The air-cooled Jupiter engines were prone to overheating and proved to only be able to lift the Do X to an altitude of 425 m (1,400 ft). The engines were supervised by an engineer, who also controlled the throttle. The pilot would ask the engineer to adjust the power, in a manner similar to that used on maritime vessels.

The engineer in the machine centre operated the throttles of the 12 engines

On its 70th test flight on 21 October 1929 there were 169 souls on board; 150 passengers (mostly production workers and their families, and a few journalists), 10 aircrew and 9 “stowaways”, who did not hold tickets. The flight broke the then world record for the number of persons carried on a single flight, a record that was not broken for another 20 years. After a takeoff run of 50 seconds the Do X slowly climbed to an altitude of only 200 m (650 ft). As a result of the ship’s size, passengers were asked to crowd together on one side or the other to help make turns. It flew for 40 minutes (Flug Revue claims it was the 42nd flight and lasted 53 minutes, and historical film shows “fliegt mit 170 personen”) at a maximum speed of 170 km/h (105 mph) before finally landing on Lake Constance.

But the Dornier was barely able to climb above 400 m (1312 ft) because of the poor cooling of the rear-mounted sextet of Jupiters, which sharply reduced their power output.

After completing 103 flights in 1930, the Do X was refitted with 455 kW (610 hp) Curtiss Conqueror water-cooled 12-cylinder inline engines. Only then was it able to reach the altitude of 490 m (1,610 ft) necessary to cross the Atlantic. Dr. Dornier designed the flying boat to carry 66 passengers long distance or 100 on shorter flights.

During a visit to England in 1930 it was piloted for 10 minutes by the Prince of Wales.

To introduce the airliner to the potential United States market the Do X took off from Friedrichshafen, Germany on 3 November 1930, under the command of Friedrich Christiansen for a transatlantic test flight to New York. The route took the Do X to the Netherlands, England, France, Spain, and Portugal. The journey was interrupted at Lisbon on 29 November, when a tarpaulin made contact with a hot exhaust pipe and started a fire that consumed most of the port side wing.

After sitting in Lisbon harbor for six weeks while new parts were fabricated and the damage repaired, the flying boat continued along the Western coast of Africa and by 5 June 1931 had reached the Capverdian Islands. Taking off from Las Palmas in the Canary Islands in high seas the hull took such a beating that another three months were wasted for repairs. Eventually it reached Natal, Brazil after crossing the Atlantic at an altitude of 6 m (20 ft) and with half her crew of 19 and much of her cargo of mail left be¬hind to save weight.

The new engines, while giving more power than the radials, burned fuel at the rate of 1820 litres (400 Imperial gallons) per hour, which meant that every non essential item had to be sacrificed. At length, on 27 August 1931, the Do X came to New York’s Battery to a ticker tape welcome, ten months after setting out from Germany.

Dornier Do X

The Do X and crew spent the next nine months there as its engines were overhauled, and thousands of sightseers made the trip to Glenn Curtiss Airport (now LaGuardia Airport) to tour the leviathan of the air. The economic effects of the Great Depression dashed Dornier’s marketing plans for the Do X, however, and it departed from New York on May 21, 1932 via Newfoundland and the Azores to Müggelsee, Berlin where it arrived on 24 May and was met by a cheering crowd of 200,000.

Two further Do Xs, the Umberto Maddalena and Alessandro Guidoni, were built for the Italian air force.

Germany’s original Do X was turned over to Deutsche Luft Hansa, the national airline at that time, after the financially strapped Dornier Company could no longer operate it. After a successful 1932 tour of German coastal cities, Luft Hansa planned a Do X flight to Vienna, Budapest, and Istanbul for 1933. The voyage ended after nine days when the flying boat’s tail section tore off during a botched, over-steep landing on a reservoir lake near the city of Passau. While the fiasco was successfully covered up and the Do X was repaired, it was then flown to Berlin, where it became the centerpiece of Germany’s new aviation museum Deutsche Luftfahrt-Sammlung at Lehrter Bahnhof, opened in 1936.

The Do X remained an exhibit until it was destroyed in an RAF air raid during World War II on the night of 23-24 November 1943, by 383 aircraft – 365 Lancasters, 10 Halifaxes, and 8 Mosquitos. Fragments of the torn off tail section are on display at the Dornier Museum in Friedrichshafen. While never a commercial success, the Dornier Do X was the largest heavier-than-air aircraft of its time, a pioneer in demonstrating the potential of an international passenger air service. A successor, the Do-XX, was envisioned by Dornier, but never advanced beyond the design study stage.

Gallery

Do XIa
Data from Flight 1930
Length: 40.1 m (131 ft 4 in)
Wingspan: 48 m (157 ft 5 in)
Height: 10.25 m (33 ft 7 in)
Wing area: 450 m² (4,844 ft²)
Empty weight: 28,250 kg (62,280 lb)
Max. takeoff weight: 56,000 kg (123,460 lb)
Engines: 12 × Curtiss Conqueror, 455 kW (610 hp)
Maximum speed: 211 km/h (131 mph)
Cruise speed: 175 km/h (109 mph)
Range w/max.fuel: 3600 km / 2237 miles
Range w/max.payload: 1100 km / 684 miles
Ceiling: 420 m / 1400 ft
Wing loading: 19.3 lb/sq ft (at 46 tons weight)
Crew: 10-14
Capacity: 66-100 passengers

Dornier Do.Q

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A 1925 Japanese collection of official papers, which was sent to Kawasaki, mentions a Do. Q aircraft as a submarine-carried aircraft.

The first paragraph reads, roughly:

“To their request, regarding the work progress of the Do. Q – (machine with Siemens motor), [would] like to share with them [Kawasaki?] that we will be expecting such a motor from the delivery company and then try to make it [Do. Q]. We assume that with this engine, a better performance of the Do. Q will be achieved.”

The second paragraph:

“[As far as] flying the Do. Q, built [using the] Le Rhone engine is concerned, it was executed some time before another flight with the maximum payload. The engine of the [Do. Q] started effortlessly in 20 seconds, however, the speed [was] very low, which was detected by [comparison to the Dragonfly (Do. A)] and it found that the rate [speed?] of the Do. Q was [inferior] to the Dragonfly. Also on the water, the rotating mass of the motor [required] that the turn down the Le Rhone engine [to] only 800 [Touren?] and the pilot is forced to temporarily turn off the ignition to the engine. The consequences of this is that the boat [was] pretty jerky and restless and rolls up after turning the ignition [on]. The flight tests were, therefore, with the Do. Q [using the] Le Rhone.”

Third paragraph:

“So we must ask them [Kawasaki?] to be patient in this affair, until we try our exports [engines] with [the] built-in Siemens motor [as we regret that opposition to ] the Le Rhone engine [has] stiffened. It will be understandable to them that the Do. Q [will] only achieve good results and for this reason [we must]refrain from [using] the Le Rhone engine.

Your faithfully,

Dornier-Metallbauten G.m.b.H.”

Dornier Do.J Wal

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The Wal all-metal flying-boat was a direct development of the Gs I of 1919 and the uncompleted Gs II.
The Wal had a two-step hull, strut-braced untapered parasol wing, sponsons, single fin and rudder, and two engines in tandem above the centre section.
The prototype flew on 6 November 1922. Because of the Allied ban on German construction of this class of aeroplane, production was undertaken by GMASA in Italy with the first aircraft completed in 1923.

LZ127 Graf Zeppelin & Dornier Wal. 1928

Passenger, mail-carrier and military versions were produced with a wide range of engines of 223.6-559kW. There were four different wing spans and the maximum weight grew from about 4,000kg to 10,000kg. Wals were also built by Piaggio and in Japan, the Netherlands and Spain, and later in Germany. About 300 were built before production ceased in the mid-1930s.

Wals pioneered air services in South America, were widely used in the Mediterranean (with eight-ten seats) and, operating from depot ships, established Luft-Hansa’s South Atlantic mail services.

To carry mail over the Berlin to Rio de Janeiro Atlantic route, Lufthansa converted the 5400 tonne Wesfalen cargo vessel into a floating airbase. The flying boat, usually a Do.J, would land near the ship, and then be hauled by a crane up a ‘dragsail’, a semi-rigid blanket that stretched into the water over the stern to act as a slipway. The Wal was then moved to the bow, from where it was launched into the air by a compressed air catapult. The complete system was first tested in June 1933, 940 miles / 1500 km off the Gambian coast.

On board a Westfalen Line ship

Gallery

Engines: 2 x RR 1928, 265kW
Max take-off weight: 4100 kg / 9039 lb
Empty weight: 2720 kg / 5997 lb
Wingspan: 26.5 m / 86 ft 11 in
Length: 16.2 m / 53 ft 2 in
Height: 4.7 m / 15 ft 5 in
Wing area: 96.0 sq.m / 1033.33 sq ft
Max. speed: 180 km/h / 112 mph
Cruise speed: 150 km/h / 93 mph
Ceiling: 3500 m / 11500 ft
Range w/max.fuel: 3600 km / 2237 miles
Crew: 2-4
Passengers: 10-12

Wal
Engine : 2 x BMW VI, 690 hp
Length : 60.039 ft / 18.3 m
Height : 17.552 ft / 5.35 m
Wingspan : 76.115 ft / 23.2 m
Wing area : 1033.344 sq.ft / 96.0 sq.m
Max take off weight : 17640.0 lb / 8000.0 kg
Weight empty : 10363.5 lb / 4700.0 kg
Max. speed : 124 kts / 230 km/h
Landing speed : 57 kts / 105 km/h
Cruising speed : 108 kts / 200 km/h
Initial climb rate : 590.55 ft/min / 3.0 m/s
Service ceiling : 9843 ft / 3000 m
Wing load : 17.02 lb/sq.ft / 83.0 kg/sq.m
Range : 1026 nm / 1900 km
Crew : 4
Armament : 2x MG15

Dornier Do.H Falke / Seefalke

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Dornier pursued the clandestine development of military aircraft, including the DoH Falke and Seefalke all metal cantilever high wing fighter monoplanes in 1922 and the DoD twin float torpedo bomber monoplane in 1926.
Manufactured at Altenrhein / Pisa, the Do.H was a relatively modern design. Fitted with floats, the Falks was available a sea-based fighter, too. Several engine variants existed.
In cooperation with Wright, the Wright H3 was fitted and the Falke offered to the US-Navy.

Dornier H Falke
Engine : BMW IV a, 296 hp
Length : 24.377 ft / 7.43 m
Height: 9.318 ft / 2.84 m
Wingspan : 32.808 ft / 10.0 m
Wing area : 215.28 sq.ft / 20.0 sq.m
Max take off weight : 2646.0 lb / 1200.0 kg
Weight empty : 2039.6 lb / 925.0 kg
Max. payload weight : 110.3 lb / 50.0 kg
Max. speed : 140 kts / 260 km/h
Landing speed : 49 kts / 90 km/h
Cruising speed : 119 kts / 220 km/h
Initial climb rate : 1161.42 ft/min / 5.90 m/s
Service ceiling : 25591 ft / 7800 m
Wing load : 12.30 lb/sq.ft / 60.00 kg/sq.m
Range : 259 nm / 480 km
Crew : 1
Armament : 2x MG

Dornier Do.C Komet I / Komet II / Do.D / Do.T / Do.B / Do.G / Merkur

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Komet II

These aircraft were three of a large family of civil/military aircraft produced in the late 1920s, and surviving documentation on their design and weaponry is both sparse and conflicting, due to the fact that Germany was officially an ‘unarmed’ country at that time.

Dornier Komet Article

Development began in 1920 with the Do C III (Komet I). This was a high wing commercial transport with an open cockpit for the pilot and an enclosed cabin seating four passengers. It had an exceptionally long wingspan of 17 m (55 ft 9.25 in) and could be powered by either a 180 hp BMW III or 185hp BMW IIIa engine. It was built in small numbers and used by various German airlines with some success.

Designed in 1920 a modified version, the Komet II, utilized the same wing configura¬tion, but with an increased overall length. The Komet II was a five-seat (pilot in open cockpit and four passengers in cabin) monoplane with a thick wing placed on top of the deep box-section fuselage. Powered by a 134kW / 250 hp BMW IV engine, it made its first flight on October 9, 1922.
A small number were built with 250 hp BMW IV engines and were operated from 1922 by Deutsche Luft-Reederei, and Rolls-Royce Falcon-engined examples went to Spain, Colombia, Russia and the Ukraine.
This was followed by the six passenger Komet III, which first flew on December 7, 1924, with a 360 hp Rolls Royce Eagle powerplant. This same engine was used in a parasol wing development, the Do C, produced shortly afterwards as a training air¬craft. Some Do Cs were operated by the Fuerza Aerea de Chile as light bombers in about 1930.

The Do D torpedo bomber, which flew for the first time in July 1926, was a twin float version of the Do C, with a 600 hp BMW VI engine, which entered limited production for the Yugoslav naval air service in 1927. In 1925, two other versions of the Kornet III were evolved: an ambulance model, designated Do T, and a passenger counterpart with a 600 hp BMW VI, the latter receiving the name Merkur (or Do B).

Do.B Merkur

The final development of the Komet type was the Do.B Merkur, which first flew in February 1925 and was produced from 1926 as an eight-ten passenger airliner powered by a BMW VI engine. It could cruise at 175km/h. Following long-distance overland trial flights, dual controls and adjustable pilot seats were fitted. Deutsche Luft-Hansa received the greatest number with nearly 30 aircraft and these operated from Berlin to Konigsberg and elsewhere. Examples were operated by Deutscher Aero Lloyd and DDL in Europe, were exported to the Ukraine and licence-built in Japan and perhaps Switzerland in civil/military guises.

Komet II D223 at Croydon Airport

Aero-Lloyd Komet II D223 was the first German commercial aircraft to visit the UK since the First World War. It brought three Aero-Lloyd directors to visit Daimler Airways to finalise arrangements for a London-Berlin service. The Komet II had flown from Berlin via Amsterdam and Rotterdam, and due to bad weather landed in a field near Lympne, Kent, where crew and Passengers spent the night before arriving at Croydon Airport.
The Komet III used three different kind of powerplants. Some of them employed the Rolls-Royce 360 horsepower Eagles, others used the Napier 465 horsepower Lions, and the third powerplant was the 400 horsepower Liberty engine.

A twin-float seaplane version was also produced and Chile received a number as Do G trainers/torpedo-bombers. The Do D was similar to the Do C built for the Yugoslav Naval Air Service, while the Do T was an ambulance derivative of the Merkur.
The Merkur used a 600 horsepower engine as its powerplant.
Production details are impossible to give. It is known that the civil Komet and Merkur series, together with the Do T, were built openly in Germany; the para military variants most likely emanated from the Dornier factory at Alteirrhein in Switzerland.

Komet II
Engine: 1 x BMW IV, 185kW
Take-off weight: 2200 kg / 4850 lb
Empty weight: 700 kg / 1543 lb
Wingspan: 17.0 m / 55 ft 9 in
Length: 10.3 m / 33 ft 10 in
Height: 3.3 m / 10 ft 10 in
Wing area: 50.0 sq.m / 538.20 sq ft
Max. Speed: 165 km/h / 103 mph
Cruise speed: 135 km/h / 84 mph
Ceiling: 5000 m / 16400 ft
Range w/max.fuel: 500 km / 311 miles
Crew: 1
Passengers: 4

Do C
Span: 19.60 m (64 ft 3.75 in)
Length: 12.43 m (40 ft 9.5 in)
Gross weight: 3900 kg (8598 lb)
Maximum speed: 195 kph (121 mph)

Do.B Merkur
Engine: 1 x BMW VI, 500kW
Take-off weight: 3700 kg / 8157 lb
Empty weight: 2280 kg / 5027 lb
Wingspan: 19.6 m / 64 ft 4 in
Length: 12.8 m / 41 ft 12 in
Height: 3.8 m / 12 ft 6 in
Wing area: 62.0 sq.m / 667.36 sq ft
Ceiling: 5200 m / 17050 ft
Range w/max.fuel: 1000 km / 621 miles
Crew: 2
Passengers: 6-7

Dornier Komet II / Komet III
Dornier Do B Merkur

Dornier D-1

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1918

Engine: 1 x BMW IIIa, 136kW
Take-off weight: 885 kg / 1951 lb
Empty weight: 160 kg / 353 lb
Wingspan: 7.8 m / 25 ft 7 in
Length: 6.4 m / 20 ft 12 in
Height: 2.6 m / 8 ft 6 in
Wing area: 18.6 sq.m / 200.21 sq ft
Max. Speed: 200 km/h / 124 mph
Cruise speed: 80 km/h / 50 mph
Ceiling: 8100 m / 26600 ft
Armament: 2 machine-guns
Crew: 1