Dornier Do 17
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| Dornier Do 17 | |
|---|---|
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| The second prototype of the Dornier Do 17 | |
| Type | Bomber |
| Manufacturer | Dornier Flugzeugwerke |
| Maiden flight | 1934 |
| Introduced | 1937 |
| Status | retired |
| Primary user | Luftwaffe |
The Dornier Do 17, sometimes referred to as the Bleistift ("pencil"), was a World War II light bomber produced by Dornier that was used at the beginning of the war by the Luftwaffe. A small run of an updated version known as the Do 215 was also produced for export, but ended up in Luftwaffe service. The successor of the Do 17 was the Dornier Do 217.
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[edit] Background and Prototypes
With the Nazi rise to power in the early 1930s one of their main priorities was to rapidly modernize their aircraft. Almost every aircraft company received orders for dramatically improved designs, typically under the guise of some sort of civilian aircraft. Fighters were "courier aircraft" and bombers airliners.
One entirely new class of design was the schnellbomber, a light bomber so fast that it would simply outrun defending fighters. For a time it was felt that bombers would retain their speed advantage over fighters due to their extra power. In order to test a series of such designs, Lufthansa placed orders for a number of "mail aircraft", which needed to be small, fast and have long range. A number of companies took this opportunity to invest in new design and construction techniques. The result was a number of world-beating designs like the Heinkel He 70 Blitz and Focke-Wulf Fw 200 Condor.
In 1933 Dornier thought it would enter the market as well, and started the design of a fast twin-engine plane in response to a Lufthansa tender, and the Do 17 was the result. In order to compete with planes like the He 70, the Do 17 was made as small as possible in cross section to reduce drag. The narrow cylindrical fuselage quickly earned the Do 17 the name "Fliegender Bleistift" ("Flying Pencil"). Three prototypes were built for Lufthansa and were tested in 1935, but they were eventually returned to Dornier. In test service the passengers had complained about the confined cabin space which made travel uncomfortable.
An order for ten aircraft was placed, three as passenger/mail planes for Lufhansa, and another seven as bombers. The original design sported a single tail, but in tests it proved to be marginally stable and a new twin-tail version was introduced, which also had the side effect of improving the field of fire for the rear gunner.
Many accounts of the Do 17 describe a Luftwaffe pilot, Flugkapitän Untucht, flying the prototype and "selling" it to his superiors as a bomber. It appears this was a cover story written after the fact.
[edit] Variants
[edit] Do 17E and F
The prototypes had mounted the excellent Daimler-Benz DB 600 engines, but these were constantly in short supply. Production started instead with the BMW VI inline engine, creating the Do 17E-1 bomber and Do 17F-1 reconnaissance versions. The bombload of the E-1 was 500 kg, and it was armed with two defensive MG15 machine guns, one in a position on the cabin roof and one a small hatch in the floor with a restricted field of fire.
[edit] Do 17K
After seeing the Do 17MV at the Zürich air races in 1937, the Yugoslavian Air Force bought licence rights for production at Drzavna Fabrika Aviona. They equipped it with the considerably better Gnome Rhône 14N radial engines and added a Hispano 20 mm cannon and three 7.92 mm Browning machine guns.
At the beginning of the April war, Royal Yugoslav Air Force was armed with 64 Do 17K (34 produced in Germany and 30 made in Yugoslavia). The only air force unit that was armed with this type was 3rd bomber regiment composed out of two bomber groups; 63rd bomber group stationed at the airport Petrovac near Skopje and 64th bomber group stationed at the airport Milesevo near Pristina. During hostilities, airplane factory in Kraljevo managed to produce three more airplanes of this type. Two were delivered to RYAF on 10th of April and one was delivered on 12th of April 1941. Between 14th and 15th of April, seven remaining Do 17K flew to Niksic airport and took part in evacuation of King Petar II and members of Yugoslav government to Greece. During this operation, Yugoslav golden reserves were also airlifted to Greece. After completing their task, five Do 17K were destroyed when Italian planes attacked Greek airport Paramitia. Only two Do 17K escaped destruction and later joined RAF in Egypt.
[edit] Do 17L and M
The Do 17L-0 and Do 17M-0 were developed in parallel as replacements for the earlier E and Fs, the L being the reconnaissance version. Both were designed around the more powerful DB 600A engines, delivering about 1,000 hp (750 kW). Two L and one M versions were built as prototypes, both with another MG15 in the nose.
The feasibility of the schnellbomber was demonstrated at the International Military Aircraft Competition at Zürich in 1937, where the Do 17M prototype finished ahead of all the fighters in the competition.
The supply of the DB 600 remained extremely limited as production was soon switched over to the fuel-injected DB 601, which was reserved for the Messerschmitt Bf 109 and Messerschmitt Bf 110. Production versions of the basic Do 17M model airframe were thus fitted with the new BMW Bramo 323A-1 Fafnir of 900 hp (670 kW), which gave reasonable performance and raised the bombload to 1,000 kg. The resulting Do 17M-1 was produced in small numbers and operated until the first year of the war, when they were withdrawn and sent to training units.
[edit] Do 17P
The L version would not be able to enter production with the DB 600, and the Bramo engine was rather thirsty and left the M models with too short a range for use in the reconnaissance role. BMW 132N radials of 865 hp (645 kW) were selected instead, which had lower fuel consumption for better range. This Do 17P-1 was produced in some numbers, but why this version was not called the L-1 is a mystery.
Another two prototypes with DB 600 engines were produced as the Do 17R-0, but did not enter production.
[edit] Do 17S and U
When fast monoplane fighters began catching up with the speed of the Do 17, a completely new pod-like cockpit was designed for the plane to give the crew more room and better visibility. The roof was extended upward over the line of the fuselage, sloping down to meet it just in front of the wing. The dorsal gun was moved to the rear of the pod where it had a considerably better field of fire. Likewise, the floor was dropped under the fuselage and the ventral gun moved to the back of the pod, allowing it to fire directly to the rear. The changes in the roof and floor made the whole front of the plane much larger.
Three prototypes with the DB 600 inverted-V engines were constructed as the Do 17S-0 reconnaissance version, but it did not go into production. An additional fifteen Do 17U-1 pathfinder models were built, similar to the S but adding an additional crewman (taking the total to five) to operate the extra radio equipment. The U models were to fly in ahead of other bombers on night missions, using the radio equipment to locate the target and drop flares on it. They were personally requested by KG 100 as experimental models for this role.
[edit] Do 17Z
Wide-scale production finally settled on the definitive Do 17Z models. At first a batch of Z-0s were built with the Fafnir for testing, the DB 600 again proving to be too hard to come by. These were quickly replaced with the Z-1 model, which added another gun for the bombardier, but the additional weight of the nose and guns meant the bombload was reduced to 500 kg.
This was addressed in the major production model, the Do 17Z-2. The Z-2 mounted the new 323P version of the Fafnir with 1,000 hp (750 kW), which was specifically tuned to the performance needs of the Do 17 by decreasing supercharger power at lower altitudes and thus improving low-level performance. The increase in takeoff power allowed the bombload to be increased back to 1,000 kg. On the downside the new engines were also quite "thirsty" at low altitudes, and the combat range with a 1,000 kg bombload was a very short 205 miles (330 km). The armament was further upgraded by adding an additional pair of guns firing out of the sides of the upper part of the pod, but as the three guns were all fired by a single gunner, only one of them could be fired at a time.
Modifications of the basic Z-2 model included the Z-3 reconnaissance version, the Z-4 dual-control trainer, and the Z-5 which included floatation cells in the fuselage and engine nacelles in case it was forced down on water. Some 537 Z-2s were produced before the lines shut down in July 1940.
During the Polish campaign, the plane could use its 265 mph (427 km/h) maximum speed to stay away from most enemy fighters, and its light armament was effective, but when it faced British aeroplanes during the Battle of Britain, it was shown that the introduction of fast, well-armed monoplane fighters had changed the balance between bombers and fighter in favour of the latter. Since the Fafnir engine was a low-altitude engine, the Luftwaffe employed the Do 17 units for a number of terrain-following mass raids in an attempt to evade fighter opposition.
With the introduction of the Junkers Ju 88, the Do 17's days were numbered, and production ended in 1940. Surviving planes were used as test beds for new technologies while many others were handed off to allied nations over the next two years. It was also the template for the much larger and totally new yet similarly looking Dornier Do 217.
[edit] Do 17Z-10 Kauz
After bomber production ended in 1940, the Z model was modified with a "solid" nose from the Ju 88C and fitted with one 20 mm MG FF cannon and three 7.92 mm MG 17s to be used as night fighters. One prototype was constructed as the Z-6 Kauz I (screech-owl), and then the design was further modified with a solid nose containing four 7.92 mm MG 17 machine guns and four 20 mm MG FF cannons to create the Do 17Z-10. Only nine of these Kauz II designs were built, fitted the Spanner-I/II infrared detection system. While the Spanner proved to be essentially useless, some planes got an upgrade to FuG 202 Lichtenstein B/C Radar in late 1941, working as a testbed to develop new aircraft radars.
The Z-10 served for two years in the night fighter role, where they were used in Josef Kammhuber's defensive system known as the Kammhuber Line. Each fighter was assigned a single "cell", with three strips of such cells running from Denmark to the middle of France. Within each cell a direction center on the ground tracked both the Kauz and a single target, guiding them until the target was visible in night glasses or the Spanner (or later, onboard radar).
[edit] Do 215
The Do 215 was developed as an export version of the Do 17Z series, but fitted with the much more powerful 1,100 hp (809 kW) DB 601B-1 V-12 inline engine. Performance was greatly improved, with top speed increasing to 290 mph (470 km/h) and service ceiling to over 31,000 ft (9,400 m).
Eighteen Do 215A-1 were built for export to Sweden in 1939, but were embargoed and instead put into service with the Luftwaffe as the Do 215B-1 and Do 215B-2. Two aircraft were sent to the Soviet Union as Do 215B-3s, otherwise unchanged. The Do 215B-4 was a reconnaissance aircraft similar to the Z-3. The Do 215B-5 Kauz III was a night fighter, similar to the Do 17Z-10. In total another 101 planes were completed as Do 215s.
The last of the Flying Pencils serves in the Luftwaffe until late 1944.
[edit] Operators
- NDH, Finland, Germany, Soviet Union (two aircraft only), Spain, Kingdom of Yugoslavia, Bulgaria.
[edit] Specifications (Do 17Z-2)
General characteristics
- Crew: four (pilot, bomb aimer/gunner, two gunners)
- Length: 52 ft (15.80 m)
- Wingspan: 60 ft (18 m)
- Height: 15 ft (4.55 m)
- Wing area: 592 ft² (55.00 m²)
- Empty weight: 11,484 lb (5,209 kg)
- Max takeoff weight: 19,500 lb (8,850 kg)
- Powerplant: 2× BMW Bramo 323P Fafnir 9-cylinder radial engines, 1,000 hp (750 kW) each
Performance
- Maximum speed: 265 mph (427 km/h)
- Range: 721 miles (1,160 km) combat (half load)
- Service ceiling: 27,000 ft (8,200 m)
Armament
- up to six 7.92 mm MG 15 (sometimes lower nose gun replaced with 20 mm MG FF cannon)
- up to 2,200 lb (1,000 kg) of disposable stores
[edit] External links
[edit] Related content
Related development
Comparable aircraft
Designation sequence
Wn 16 - Do 16 - Do 17 - Do 18 - Do 19 - Do 20 - Do 22
