Dornier Thu 18
| Dornier Thu 18 | |
|---|---|
|
|
| Type: | Flying boat |
| Design country: | |
| Manufacturer: | |
| First flight: |
March 16, 1935 |
| Commissioning: |
July 3, 1936 |
| Number of pieces: |
170 |
The twin-engine Dornier Do 18 flying boat was designed by Dornier Metallbauten GmbH in Friedrichshafen . It was built in the early 1930s for both civil and military use. Its predecessor was the globally proven whale , which was manufactured from 1922 to 1935. Its designation, Do J, was changed to Do 16 around 1932. Both the whale and the Do 18 had the usual features of Dornier at the time, such as the wings mounted high above the fuselage on a scaffolding with two motors arranged one behind the other, each driving a pulling screw and a pushing screw. In addition, there were the patented fin stubs protruding from the hull on both sides, which ensured swimming stability and at the same time served to hold part of the fuel supply.
The genesis
Unlike in most cases at the time, the Do 18 owes its creation neither to an urgent request from the Army Armed Forces Office , which was already secretly planning the establishment of an air force, nor to a request from Deutsche Luft Hansa (DLH) . It was Dornier Metallbauten GmbH itself that at the end of 1932, concerned about the capacity utilization, especially in production, but also in the design department, approached the two previous German operators of these flying boats as possible buyers with the suggestion of a further development of the tried and tested "Wals".
Neither of them responded immediately. The air force planners relied on a three-engine flying boat as a maritime patrol plane, but for much later. In the end, two samples were planned for development, one also at Dornier ( Do 24 ) and one at the newly established company Hamburger Flugzeugbau (Ha 138 and BV 138 ).
At that time, DLH had another major project to deal with, the Do 14 transocean approach boat, also under construction at Dornier , which with its unusual propulsion system (two BMW VIs with gearboxes in the fuselage and two angular drives with intermediate shafts to drive the only one on a high Bock seated four-blade propeller) caused constant postponements and difficulties. That was probably the main reason for the reluctance of the DLH towards Do 18.
On the other hand, in the longer term, DLH had high hopes for the four-engine replacement of its two existing 8.6-t whales, with which the postal service to South America via the South Atlantic was just starting at the time, and the 10-t whales ordered for this purpose Delivery should be made shortly. The government development contracts, which were also expected for this, went two years later to the same plants that were also working on the long-range reconnaissance vehicles, namely Dornier for the Do 26 and HFB for the Ha 139 . However, since all four projects were still far from being available, both sides accepted the suggestion, although both the DLH and the Heereswaffenamt left no doubt that they viewed the Do 18 only as a makeshift.
In the long drawn-out negotiations on the design, as in other projects, the demands of the military side, which had been declared to be priority, caused difficulties. This mainly affected the engines to be installed. The military side insisted until the end on the BMW VI, which was used in a large number of the aircraft in operation or continuously in service. For economic reasons, however, the DLH preferred the new, fuel-efficient and therefore very economical engine Jumo 5 , later 205. They also included the Hispano-Suiza 12Y in their considerations. After much back and forth, they agreed on the Jumo 5 for both versions. On March 10, 1933, the company then submitted an offer for three Do 18 flying boats to the now responsible Reich Commissioner for Aviation , with the extremely short deadlines particularly striking. The first test aircraft should have come into flight in November 1933 and the second in February 1934. These were dates that soon turned out to be completely untenable.
The people in charge at Dornier were probably not yet clear about the enormous change and what much higher workload the use of multi-axis curved sheets for the first time meant for production, which was exactly the case for the Do 17 , which was being created at the same time . The now existing Reich Aviation Ministry (RLM) awarded the company an order for the construction of initially two flying boats on August 7, 1933, in response to this offer and two more subsequent ones with associated building specifications, of which the first, labeled "A", should go to the DLH, while the second, with the designation "C", is to be delivered to the Lucht office . Here, too, the commercial flying boat was used to camouflage the first long-range reconnaissance aircraft that followed immediately afterwards for the new air force. The civilian flying boat was to be built in Duralplat, the second military one in the then newly developed, particularly seawater-resistant alloy hydronalium .
The testing
Flight captain Erich Gundermann made the first flight with the Do 18 A, (later designated V1) Wnr. 253, D-AHIS, intended for the DLH on March 16, 1935 in Friedrichshafen. That was 1 ½ year later than assumed by the company at the time. Further difficulties arose during the first flights due to the two-spar high-deck wing, which turned out to be too soft and therefore prone to vibrations. Only the ever-increasing replacement of the initially pure fabric covering with sheet metal cladding brought relief. This first aircraft, which was called monsoon in the old DLH tradition , was lost during testing by Lufthansa on November 2, 1935 in a high-speed low-level flight after contact with water. Two of the crew, which was made up exclusively of DLH members, were injured, but only three were rescued dead. The tests now had to be continued with the second aircraft, the Do 18 C, D-ADIR (Wnr. 254). It soon became apparent that the problems with the wing had not yet been resolved despite all the changes adopted from the first aircraft. During the seventh workshop flight on November 19, the left aileron tore off after it had started to vibrate.
After further improvements and static vibration tests, the machine now known as V2 was able to take off on its second maiden flight on July 14, 1936. However, it took until August 8th before the aircraft could be presented to the DVL / PfL (German Research Institute for Aviation / Test Center for Aviation Equipment) for a type test , which granted approval five days later. This aircraft has remained virtually unknown to literature. It then went to the E-point in Travemünde for flight and weapon testing , where it must be proven by November 23, 1938. Both V1 and V2 were still equipped with Jumo 5 B engines, which can be recognized by the central output - the propeller shaft was located on the middle of the five gears at the front of the engine that brought together the power of both crankshafts. That meant left-hand propellers, a direction of rotation that is otherwise not common in German engines. However, these engines were replaced by the Jumo 205 C of the 1 series during testing, which then acted on normal clockwise propellers due to the top downforce. The V2, the second aircraft intended for military purposes, just like the V4, which was still heavily delayed, initially had two defensive posts on the back of the fuselage, which were slightly offset from one another both laterally and longitudinally. This order was abandoned in favor of a single armory.
On January 21, 1935, before the first aircraft was ready to fly, the RLM ordered 27 Do 18 aircraft, five of which were intended for development, and five more in the Do 18 C version as a pilot series for military use. Of the five development aircraft, the V1, V3 and V5 were intended for testing and determining their suitability for the DLH, while the V2 and V4 in version C were intended for military testing.
Thu 18 at DLH
As planned, the DLH was the first flying boat to receive the Do 18 E V3, which was approved as D-ABYM and was named after the Greek wind god Aeolus . It became the property of the company on July 3, 1936 when it was bought by the RLM for 236,500 Reichsmarks. This was the price of a production aircraft, which means that the entire development costs, as usual, were borne by the RLM and that DLH did not have to pay any part of them. Flight captain Joachim Blankenburg familiarized himself with the V5 D-ARUN, which was christened "Zephir", from July 18 to 21, 1936 in Friedrichshafen. This flying boat was also sold by the RLM to the DLH on August 25 for the same price. It was different with the other two Do 18s, once the V6, D-AROZ “Pampero” ordered as a replacement for the lost V1, and the last V7, D-AANE “Zyklon” delivered on June 28, 1937. They were no longer commissioned by the RLM, but by the DLH itself, but certainly in coordination with the ministry. While the first three were all designated Do 18 E, the V7 remained the only F version aircraft that differed in its wingspan increased to 26.3 m (instead of 23.7 m for all other Do 18). Since this was achieved by inserting a wing center section with the outer wings remaining unchanged, the now considerably longer wing struts had to be intercepted roughly in their middle by auxiliary struts towards the underside of the wing in order to prevent bending vibrations. This detail makes the aircraft easy to recognize on images from almost all directions. Thanks to its reduced wing loading, the D-AANE was the only Do 18 that could maintain its flight altitude when loaded with just one engine.
In its first use, DLH tried out the possibilities of a postal service across the North Atlantic with the Do 18. On 10/11 September the D-ARUN “Zephir” flew after its catapult launch from the Schwabenland in front of Horta under Blankenburg and Lufthansa director Freiherr Carl August von Gablenz in 22:18 hours to New York. On September 11th, D-ABYM “Aeolus” followed under Hans-Werner von Engel and Freiherr von Buddenbrock on a more southerly route to Hamilton (Bermuda) , (3320 km / 18:15 h). With a water start, the “Aeolus” continued the flight to New York in seven hours the following day. Since the planes needed a catapult launch from the Swabia for the flight over the North Atlantic, the latter marched first to New York and then to Bermuda. On September 22nd, the "Aeolus" flew from New York back to Horta in 17:50 hours (3850 km). The "Zephir" was catapulted off Hamilton to Horta on September 28th. The second flights to New York followed on 5th / 6th. or 6./7. October and the return flights this time on October 17th and 18th from Sydney (Nova Scotia) . The flying boats did not wait for the Swabia , but continued their return flight from the Azores via Lisbon to Travemünde . Lufthansa repeated such tests in 1937 and 1938 with the four-engine Blohm & Voss Ha 139 planned for this route.
The DLH took its time with the use of the four flying boats in the postal service on the South Atlantic. It was not until April 11, 1937 that the V5, D-ARUN “Zephir”, flew as scheduled, followed by the V3, D-ABYM “Aeolus” on the 30th of the month. The use of the Do 18 was not a particularly good star. The V3 "Aeolus" had to be written off completely after an emergency landing in the Atlantic on July 30, 1937 due to severe damage during the attempted salvage. The V5 and V6 also landed outside, but the damage could be repaired. On the night of September 30th to October 1st, 1938, V6 “Pampero” with a crew of five disappeared without a trace shortly before landing in Bathurst. All searches were unsuccessful.
The four Do 18 were never able to completely replace the Dornier Wal (72 flights in 1937, 54 flights in 1938, last on October 28) and crossed in the almost two years of their service from April 11, 1937 to April 2, 1939 (V7 "Zyklon") a total of 73 times the South Atlantic until it was replaced by the four-engine float planes Blohm & Voss Ha 139 (first used on May 13, 1938) and the Dornier Do 26 flying boats (first used on April 7, 1939) which could not be used on their planned route over the North Atlantic due to a lack of US approval. The two remaining Do 18E V5 D-ARUN "Zephir" and Do 18F V7 D-AANE "Zyklon" of the DLH were handed over to the Air Force as school machines.
The world record
The Do 18 W, D-ANHR, in which the W explains its purpose, namely the establishment of a long-distance world record, was not an F, but a normal D (WNr. 734) without armament. It was also not part of the DLH fleet, but remained with the company as a Reich-owned aircraft, where it was prepared for the record attempt and provided with special equipment. Since the company did not have a crew with transocean experience, flight captain Hans-Werner von Engel , radio operator Helmut Rösel and aircraft radio operator Hans-Joachim Stein from DLH joined the company, which is now called Dornier-Werke GmbH had changed. Flight captain Erich Gundermann was the only employee to join the company as the second pilot.
On March 27, 1938 the time had come. The catapult ship Westfalen made available by DLH had anchored briefly with the D-ANHR on board from Bremerhaven on the way to its place of operation near Bathurst , Gambia , southeast of the English port of Dartmouth : 05:00 GMT to get into the air with the catapult. The launch point was chosen so that from there the entire route to Brazil could be flown over the sea in a great circle . Two days later, on March 29 in the morning at 10:05 a.m., the flying boat landed at the small town of Caravelas in Bahia (Brazil) after 43 hours and 8392 kilometers . A new long-distance world record was set.
On March 30th the flight to the planned destination Rio de Janeiro took place . The return flight took place from April 6th to 15th via Fernando de Noronha and Las Palmas to Travemünde.
Other engines
In order to cope with the troops' constant complaints about insufficient engine power for the water start and single-engine flight, the RLM asked the company to examine the possibility of installing more powerful engines. For this purpose, the D-ANHR, which was now freely available after the world record, was chosen, which has now been converted to air-cooled BMW-132 -M engines and thus as the Do 18 L (initially with its civilian license number, later with the regular military license number CO + JF ) was tested. A whole series of problems had to be solved. For example, routing the cooling air for the rear engine caused some difficulties. It had to be caught with a scoop on the top of the motor nacelle, deflected by 180 ° and pushed through the cylinder star by a specially built-in fan wheel in the direction of flight, so that after the direction of flow was reversed again, it emerged through adjustable flaps on the right and left sides. At the same time, the aircraft had received the sharp-edged so-called "cruiser bow" proposed by the E -stelle Travemünde , which protected the front glazing of the driver's cab better from splashing water than the rounded bow in earlier versions. The first flight took place on November 21, 1939 in Manzell. Since the Luftwaffe's interest in the Do 18 had already decreased significantly when the Blohm & Voss BV 138 became available, this one aircraft remained, which probably ended up at a school.
The Do 18 in the Air Force
The Air Force had always only viewed the aircraft as a makeshift until the three-engine Blohm & Voss BV 138 or Dornier Do 24 were ready for action, because the ability to fly with only one engine was severely restricted. Nevertheless, the V2, WNr. 254, D-ADIR and the V4, WNr. 662, D-AHOM, were tested at the E -stelle Travemünde with a positive result for their suitability as long-distance reconnaissance. The V4 was also the only Do 18 with a double vertical tail. It also served as a model aircraft for the series D-0 that followed, but in which the simple vertical stabilizer was used again. At Dornier in Friedrichshafen-Manzell, after the seven test aircraft, a total of 41 Do 18s in the versions D-0 (seven pieces), D-1 (six pieces), D-2 (ten pieces) and D-3 (16 Pieces) as well as the first two of the H series, which were equipped with double controls for training. The remaining 122 of the 165 Do 18 built for the Luftwaffe were built by Weser-Flugzeugbau in Einswarden by August 1940 in the versions D-3 (40), G (62) and H (20). The model aircraft for the G version (there was no G-1) was Wnr.V841, D- or WL-ADBA, which was built at Weser in early 1939. At the E -stelle Travemünde, where it went after completion, it received the TJ + HP registration number at the end of 1939. Their main feature were the fin stubs that were about 30 cm wider on each side in the direction of the span. On September 1, 1939, 62 Dornier Do 18s (58 operational) were the only flying boats in the Luftwaffe's inventory, since the BV 138, which the RLM had decided on, was not yet available when the war broke out. The six flying boat squadrons of the coastal aviation groups with their slow and initially only weakly armed Do 18 D carried the brunt of the reconnaissance over the sea, and they also suffered high losses. In 1940 some squadrons moved their base to Norway. The underpowered and outdated flying boats were soon used primarily as training machines. In mid-1941 only one squadron with Do 18 was in the front line. The Blohm & Voss BV 138 or agricultural machinery had replaced the Dornier.
A Do 18 N which is mentioned in the literature and which has been converted for distress at sea can not be specifically proven, but occasionally Do 18 D or G seem to have been used for rescue from distress at sea , for which they are not very suitable. The rescued persons, five at a time at most, could only be brought into the boat through the hatch in the tank room and then had to be brought into the not particularly spacious hold through the narrow bulkhead door. Obviously, the right fuselage tank could also be removed for this mission and replaced by a box that offered space for three seating options with appropriate seat belts. Here, too, the Do 18 could only be seen as a makeshift, which soon became superfluous due to the Dornier Do 24, which had to be built in the occupied Netherlands.
The Blohm & Voss BV 138, on the other hand, which at the time had been preferred to the Do 24 as a maritime patrol aircraft by the relevant authorities, turned out to be completely useless for use at sea. It gradually replaced the Do 18 from the front line. However, towards the end of the war, some Do 18 were still equipped with FuG 200 ship search devices at the Travemünde electrical station and used in the Baltic Sea to fight Soviet submarines, because diesel fuel was still more available than aviation fuel at that time. Not a single Do 18 was preserved.
technical description
hull
The hull was a completely closed boat made of frames and longitudinal beams, planked on all sides with smooth dural sheet metal. At the front it had an aerodynamically rounded bow, which from the D-3 version onwards was replaced by a sharp-edged, so-called cruiser bow due to the obstruction of view during take-off by spray. Of the 36 main ribs, seven were fully-walled with watertight doors. The trunk cross-section was almost semicircular in the middle and towards the rear. The stern pulled upwards merged into the fin. The floor, which was reinforced to absorb the water puffs, was strongly keeled at the front and had a heel running parallel to the keel in the rear half of the front section up to the transverse step on each side. From the step to the rear, the so-called spur box, which was also keeled, protruded from the ground. It ended in a vertical cutting edge, behind which the simple water rudder sat (only up to and including D-2, from D-3 then two oars pushed out to the side). On top of the fuselage was the gondola bracket that contained the two water coolers at the front. It was so wide that the flight mechanic could get through it to the rear of the two engines during the flight. The access shaft was also accessible from the outside through doors on both sides. On the right and left, the fin stubs protruded from the fuselage, which due to their shape generate little resistance but also some buoyancy. In them were the cross members connected to the fuselage frames 11 and 14, which absorbed the forces of the wing struts. In addition, part of the fuel was housed in a tightly riveted space in each fin stub. The two main containers were stored in the fuselage. Starting from the front, the hull was divided into the bow space, which was closed at the top with a lid for civilian use. A weapon stand was installed there for military use. Behind it came the driver's cab with single or double steering, followed by the navigation room, which was illuminated by a round window on the right and left. This was followed by the fuel compartment, where the tanks could be installed and removed thanks to a square cover installed at the top left. This tightly screwed lid was a supporting element of the fuselage structure. Behind this room was the hold, which was lit by a round window on the right that could be opened from the inside. The rear armament of the military aircraft was installed in the stern room that followed. This included a hinged windbreak. Most of the rescue equipment was also housed in this room.
Tail unit
The ailerons were arranged in the manner of Junkers double wings behind and below the trailing edge of the wing and were used as landing aids together with the landing flaps forming the extension. The horizontal stabilizer sat halfway up the vertical fin and was supported by two struts towards the fuselage. The fin of the vertical stabilizer was molded into the fuselage. All rudders were aerodynamically and mass-balanced light metal frames, mostly with a tube as a spar and covered with fabric. They were operated via bumpers with cables and / or chains. The horizontal stabilizer was adjustable with the help of a mechanically driven threaded spindle, for which the two front support struts were guided through covered slots in the fuselage wall to the adjustment gear located in the middle of the fuselage.
Structure
The supporting structure was formed by two roughly trapezoidal, semi-circular rounded wing halves, which were fastened to the supporting structure of the gondola trestle with bolts and supported against the fin stubs with two stems each, which were crossed out by tension wires. The structure was two-spar with cross bars and ribs, six of which at the rear end carried the downward-bent bearing arms for ailerons and landing flaps. The profile thickness increased from the root rib to the outside until the greatest thickness was reached at the point of the stem connections. From there outwards it took off again. Almost the entire surface of the wing was planked with smooth dural sheet, only a few fields in the rear area were covered with fabric. The two lubricant reservoirs and the associated coolers were located between the front and rear struts near the root of the surface; they were accessible from below.
Engines
The two engines were installed one behind the other in the aircraft axis above the nacelle. The front motor drove a three-bladed VDM adjustable propeller made of metal with a diameter of 3.3 meters, the rear motor, via a long-distance shaft, a pressure screw from the same manufacturer with a diameter of 3.2 meters. While in the earlier versions some of the exhaust gases were let out directly into the open from the nozzles on the cylinders, from version D on there was a collector on each side of the engine, from which the exhaust gas in the front engine was accommodated through pipes into the wing noses Junkers silencer, at the end of which it emerged about one meter away from the engine casing on the upper side of the wing. In the rear engine, the well-insulated silencers were located above and along the long-distance shaft, with the outlets on the right and left at the rear end of the engine cowling about half a meter in front of the propeller. The water coolers for both engines were installed one above the other in the front open nacelle bracket. The cooling air flow could be regulated with the help of semicircular flaps arranged inside the front panel.
Armament
Up to the first G aircraft, the Do 18 was armed with hand-operated slewing ring mounts D 30 with MG 15 in the two gun stands in the bow and on the back of the boat, which were later replaced by MG 131, in some cases in the troops. It was not until the G version was being manufactured that the D-30 mounts in the B stand were replaced by hydraulically operated HDL 151s with a 20 mm MG 151. These could also be retrofitted in earlier aircraft. The open turntable remained in the bow. In addition, there was a drop armament, which consisted of suspension devices for two 50 kg SC 50 bombs under the right wing directly next to the front wing handle.
Others
The nautical equipment included a light anchor with a line, a sea anchor with a line, a throwing line, a flashing light for signaling and a cover for the bow stand. A signaling system with push-button switches and Bosch horns was installed in all rooms for mutual understanding between the crew, which was particularly important when using a catapult. The flight, navigation and engine monitoring devices were arranged in the equipment panel below the pilot's windshield, some of them also in the navigation room. Hand-held fire extinguishers were fastened within easy reach in the access shaft (two pieces), in the navigation and in the cargo hold. In the navigation room, an Allweiler hand pump was attached to frame 10 for pumping out (draining) water that had entered. A dinghy with two paddles, two emergency food containers, a flare gun with ammunition and a box for storing life jackets were located in the stern area as rescue equipment.
To move the aircraft on land, there were wheels attached to the outside of the fin stubs, which were supported there by two longitudinally adjustable struts leading to the connection points of the wing handles. In addition, a two-wheeled turntable cart with a long drawbar was added, which was firmly connected to it by two straps looped around the end of the fuselage, thus enabling towing and maneuvering.
Executions
- Thu 18 A - 1 aircraft for the DLH with 2 × Jumo 5 engines each with 540 PS (397 kW)
- Do 18 C - 2 planes (V2 with Jumo 5 engines, each with 540 HP (397 kW) and V4, with Jumo 205 C)
- Do 18 D - 79 aircraft with 2 × Jumo-205-C engines with 600 HP (442 kW) each, series D-0 to D-3, WNr.734 converted to Do 18W D-ANHR
- Do 18 E - 3 aircraft with 2 × Jumo 205 C engines each with 600 PS (442 kW), V3, V5 and V6 for DLH
- Do 18 F - 1 aircraft with 2 × Jumo 205 C engines each with 600 PS (442 kW), V7 for DLH
- Do 18 G - 62 aircraft with 2 × Jumo 205 C or D engines, each with 880 PS (648 kW) for the Air Force
- Thu 6 PM - 22 PM training aircraft with dual controls, + conversions (?)
- Do 18 L, converted from the Do 18 W with 2 × BMW-132-M radial engines
Technical specifications
Dornier Do 18 D, G and H :
| Parameter | Data |
|---|---|
| length | 19.25 m or 19.38 m |
| Wingspan | 23.70 m or 26.3 m (Do 18 F) |
| Wing area | 98 m² or 111.2 m² |
| height | 5.35 m |
| drive | two Jumo 205 C, 600 HP each; later also D-engines with 880 PS (648 kW) each |
| Top speed | 260 km / h |
| Range | 3,500 km |
| crew | four men |
| Service ceiling | 4,200 m |
| Empty weight | 5,850 kg |
| All-up weight | 10,000 kg |
| Armament | one MG 15 or one MG 131 , one 20 mm MG 151 , two 50 kg bombs |
See also
literature
- Graue / Duggan: DEUTSCHE LUFTHANSA, South Atlantic Airmail Service 1934–1939. Zeppelin Study Group, 2000.
- Jörg-M. Hörmann: Flugbuch Atlantik, German catapult flights 1927–1939. Delius Klasing Verlag, 2007.
- Jet & Prop: Article Poetry and Truth about the Dornier Thursday 18. Issues 4, 5 and 6/94 and 1/95.
