Do 17Z-2 Specifications
Crew: Pilot and four gunners/navigators/bomb-aimers
Powerplant: Two 1,000 hp Bramo 323P nine-cylinder air-cooled engines
Span: 59 ft ¾ in (18.00 m)
Length: 52 ft 0 in (15.85 m)
Max Speed: 265 mph (427 km/h) at 16,400 ft (4,998 m)
Armament: Between four and eight 7.92 mm machine guns in front, rear and beam cockpit mountings and ventral position
Bomb Load: Normal load of 2,200 lb (1,000 kg)
Image: A Dornier Do 17Z bomber of KG 76 in flight, 1940. Bundesarchiv, Bild 101I-341-0489-10A / Spieth / CC-BY-SA 3.0
Introduction
The Dornier Do 17 was a German twin-engined bomber and reconnaissance aircraft that served during the opening campaigns of the Second World War and the Battle of Britain. Developed around the Schnellbomber, or “fast bomber”, concept, it was intended to rely upon speed to evade enemy fighters rather than carry extensive defensive armament.
The aircraft was the least numerous of the three principal medium bombers employed by the Luftwaffe during the Battle of Britain. Its narrow fuselage produced a compact silhouette, while its responsive handling made it particularly effective at low altitude. These qualities earned the Do 17 considerable popularity among its crews and made it a difficult target to hit compared to the larger Heinkel He 111 and Junkers Ju 88.
By 1940, however, the speed advantage upon which the original design depended had largely disappeared. The Do 17 carried a smaller bomb load than the He 111, lacked the speed and versatility of the Ju 88 and remained inadequately protected against modern fighters. Although it continued to perform low-level attacks with considerable effectiveness, the Battle of Britain exposed the limitations of the Schnellbomber concept and brought the aircraft’s career as a principal Luftwaffe bomber towards an end.
Its long, slender fuselage gave the Dornier its best-known nickname: Fliegender Bleistift, or “Flying Pencil”.
Development and Design
The Do 17 originated at Dornier Flugzeugwerke as a high-speed civil transport for Deutsche Lufthansa. Three prototypes were built, but Lufthansa rejected the aircraft because its narrow fuselage provided insufficient space for passengers and cargo. Its military potential was subsequently recognised by Flugkapitän Robert Untucht, who flew one of the prototypes and concluded that its speed and slender airframe made it well suited to the bomber role. At Untucht’s urging, Dornier adapted the design to meet the Luftwaffe’s Schnellbomber requirement, creating an aircraft intended to evade interception through speed.
The first prototype flew in the autumn of 1934. The subsequent military redesign incorporated an internal bomb bay, defensive armament, a glazed nose and twin vertical tail surfaces. The crew was concentrated in the forward fuselage, improving communication between the pilot, observer and gunner.
The first military versions selected for series production in early 1936 were the Do 17E-1 bomber and Do 17F-1 reconnaissance aircraft. Both were powered by two 750 hp BMW VI inline engines and could exceed 240 mph (386 km/h) in level flight. The E-1 carried an internal bomb load of up to 750 kg (1,654 lb), while the F-1 replaced bombing equipment with cameras and additional fuel for long-range reconnaissance. Defensive armament initially consisted of two 7.92 mm MG 15 machine guns covering the dorsal and ventral approaches.
In July 1937, the experimental Do 17M V1 appeared at the International Military Aircraft Competition in Zürich. Powered by two Daimler-Benz DB 600A engines, it reached 284 mph (457 km/h) and proved faster than every fighter taking part. Limited availability of the DB 600 prevented this version from entering mass production.
The production Do 17M bomber instead used BMW-Bramo 323A-1 Fafnir radial engines, while the parallel Do 17P reconnaissance aircraft received 865 hp BMW 132N engines to provide greater range. The M could carry 1,000 kg (2,205 lb) of bombs and introduced a fourth crew member, although its maximum speed fell to approximately 261 mph (420 km/h).
As fighter performance improved, the Do 17’s original speed margin began to diminish. The definitive Z series was therefore developed with better protection, increased crew space and stronger defensive armament, requiring a complete redesign of the forward fuselage.
The cockpit roof was raised and fully glazed, while the glazed bombardier’s position occupied the nose. The lower fuselage was enlarged into a ventral gondola extending aft towards the wing leading edge. The roomier compartment could accommodate a crew of up to five and provided additional defensive positions.
The new forward fuselage first appeared on the DB 600-powered Do 17S high-speed reconnaissance aircraft, which did not progress beyond evaluation. A similarly configured Do 17U pathfinder followed, but only twelve were built before attention shifted to the Z series. Because DB 600 engines were required for Germany’s expanding fighter programme, the Do 17Z received BMW-Bramo radial engines.
The Do 17Z-1 retained the manoeuvrability and handling of the earlier aircraft, but the additional crew, equipment and armament left it underpowered. Its bomb load was therefore reduced by half. The Z-2 resolved this deficiency in early 1939 by introducing BMW-Bramo 323P Fafnir engines with two-speed superchargers, restoring the full 1,000 kg payload. The additional bomb load required reduced fuel capacity, however, restricting operational range to approximately 205 miles (330 km).
Defensive armament increased to six 7.92 mm machine guns: one fixed and one flexible weapon firing forward, dorsal and ventral guns covering the rear, and one gun in each side window. These weapons were mounted individually and had restricted fields of fire, leaving important gaps in the aircraft’s defence.
Entry Into Luftwaffe Service and the Second World War
The Do 17E and F began reaching front-line Luftwaffe units in early 1937. From the spring of that year, both variants were tested in combat during the Spanish Civil War. They performed effectively under relatively favourable conditions, but the appearance of more capable fighters demonstrated that speed alone could no longer guarantee protection.
Production shifted to the Do 17M bomber and Do 17P reconnaissance aircraft during late 1937. By September 1938, the Luftwaffe had 479 Do 17s in four variants on strength from a total of 580 delivered by Dornier.
The Do 17Z subsequently became the definitive bomber version. It was highly regarded by both aircrew and ground personnel and proved the most reliable of the Luftwaffe’s principal bombers. Nevertheless, it lacked the load-carrying capacity of the He 111 and the speed of the Ju 88. Production was already declining by the end of 1939, and the final 500 Do 17Z-1 and Z-2 bombers and twenty-two Z-3 reconnaissance-bombers had been delivered by early summer 1940.
At the beginning of the Polish campaign, the Do 17 and He 111 formed the backbone of the Luftwaffe’s bomber force. Kampfgeschwader 2, 3, 76 and 77 operated 533 Dorniers. KG 76 and KG 77 still flew the Do 17E, while KG 2 and KG 3 had converted to the Do 17Z. Numerous Do 17M-1 and P-1 reconnaissance aircraft also served with Aufklärungsstaffeln across the four Luftflotten.
Do 17Zs of III./KG 3 bombed the approaches to the railway bridge at Dirschau forty-five minutes after the official outbreak of the war. The four Dornier-equipped Kampfgeschwader subsequently attacked Polish airfields, ammunition dumps, troop concentrations and targets of opportunity. Only a small number of aircraft were lost, principally to ground fire, because crews could usually outrun Polish fighters.
Only reconnaissance Do 17Ps participated in the Norwegian campaign during April 1940. The following month, KGs 2, 3 and 4 operated under Fliegerkorps II during the invasion of France and the Low Countries, while KGs 76 and 77 were assigned to Fliegerkorps I and VIII.
The Do 17’s limited range and bomb load reduced its usefulness as the campaign advanced, but its manoeuvrability and low-altitude performance remained valuable. On 10 May, KG 2 attacked the RAF-controlled airfield at Vraux, destroying six Bristol Blenheim IVs and two Fairey Battles and damaging several other aircraft. Nineteen Do 17s from KG 2 and KG 3 were lost to Allied fighters on the same day.
The Dornier units later operated extensively over the Dunkirk evacuation beaches. On 2 June, renewed RAF fighter opposition resulted in the destruction of sixteen Do 17s. By the fall of France, the Dornier Kampfgeschwader had dropped approximately 350 tons of bombs during the campaign.
The Do 17 in the Battle of Britain
Losses suffered in France had not been fully replaced when the Battle of Britain began, and several former Do 17 units were already converting to the Ju 88. KG 2 remained fully equipped with Dorniers and was assigned a leading role in the Kanalkampf against British convoys during July 1940. KG 3, KG 76, KG 77 and numerous reconnaissance Staffeln also operated the type during the campaign.
On Adlertag, 13 August 1940, Do 17Zs of III./KG 2 attacked RAF Eastchurch and lost five aircraft. Two days later, eighty-eight Dorniers—the entire serviceable strength of KG 3—bombed Eastchurch and Rochester. On 16 August, I./KG 2 and III./KG 76 attacked RAF West Malling.
On 18 August, later remembered as the “Hardest Day”, Do 17Zs of I. and III./KG 76 mounted attacks against RAF Kenley and RAF Biggin Hill. Nine Do 17s of 9./KG 76 approached Kenley at extremely low altitude, using the terrain and surprise to penetrate the airfield’s defences. The attack damaged or destroyed hangars, buildings and aircraft on the ground, but the German formations suffered heavily with only three aircraft returning safely to base in France.
Dornier units specialised in terrain-following raids because the aircraft’s robust radial engines and responsive handling performed particularly well at low altitude. Its strong structure could withstand the stresses of these operations, while the Do 17 could reach approximately 370 mph (595 km/h) in a shallow dive. Crews relied upon manoeuvrability, surprise and low-level speed to evade interception.
The aircraft’s defensive armament remained inadequate. Forward maintenance units added two more MG 15 machine guns firing laterally from the radio operator’s position, but the individually mounted weapons retained restricted arcs of fire and could not provide complete coverage against coordinated fighter attacks.
The Do 17’s low-altitude advantages became less relevant after 7 September, when the Luftwaffe switched to large formation attacks against London at medium altitude. Losses mounted rapidly. On 15 September, the three remaining Dornier-equipped Kampfgruppen lost twenty aircraft destroyed and another thirteen damaged.
Among the bombers brought down that day was a Do 17Z-2 (W.Nr. 2361, F1+FH) of 1./KG 76. Sergeant Ray Holmes of No. 504 Squadron collided with the Dornier over central London causing the bomber to crash near Victoria Station. Holmes abandoned his damaged Hurricane fighter and survived.
During August, fifty-four Do 17s were lost in combat and another twenty were written off because of technical problems or accidents. Heavy attrition continued through September and October. Official Do 17 losses during the Battle of Britain were recorded as 132 aircraft, the lowest total among the three principal German bomber types involved.
The cumulative losses reduced the Dornier force to the point that the majority of the subsequent night Blitz was conducted by units equipped primarily with the He 111 and Ju 88. The Battle of Britain therefore marked the end of the Do 17’s period as one of the Luftwaffe’s principal front-line bombers.
Strengths and Limitations
The Do 17’s principal strengths were its responsive handling, compact profile and durability. It was unusually manoeuvrable for a twin-engined bomber, particularly at low altitude, while its air-cooled radial engines were comparatively resistant to battle damage. These qualities made it well suited to fast, low-level attacks in which surprise and accurate flying were more important than a heavy bomb load.
The aircraft had originally been conceived around speed, and early versions could outrun many contemporary fighters. Its clean airframe and precise handling remained valuable in tactical bombing and reconnaissance, while the redesigned forward fuselage of the Z-series improved visibility and allowed the closely grouped crew to communicate effectively. Under favourable conditions, the Do 17 could therefore be an accurate and effective light bomber.
By 1940, however, its speed advantage had largely disappeared. Modern fighters could intercept it without difficulty, and the addition of further defensive machine guns did not provide adequate protection against coordinated attacks. Although the weapons covered several directions, they lacked the concentrated firepower needed to deter determined Spitfire and Hurricane pilots.
The Do 17 also carried fewer bombs than the He 111 or Ju 88 and had a comparatively restricted operational radius. Its modest payload limited the damage it could inflict on major targets, while its range reduced the flexibility available to Luftwaffe planners. The combination of limited offensive capacity and increasing vulnerability left the aircraft poorly suited to the sustained strategic bombing campaign demanded of it in 1940.
Legacy
The Battle of Britain effectively ended the Dornier Do 17’s career as one of the Luftwaffe’s principal front-line bombers. Production had already ceased by early summer 1940, and surviving units increasingly converted to the faster and more versatile Ju 88. The declining strength of the Dornier units also meant that the He 111 and Ju 88 carried the greater share of the subsequent night Blitz.
The Do 17 nevertheless remained an important example of the Schnellbomber philosophy that shaped German bomber development during the 1930s. Its success in Poland and the early stages of the war demonstrated the value of speed and low-altitude manoeuvrability, while its losses over Britain showed how quickly those advantages could disappear when confronted by modern fighters and an organised air-defence system.
The closely related Dornier Do 215 extended the basic design. Externally similar to the Do 17 but powered by Daimler-Benz DB 601 inline engines, it was originally intended for export to Yugoslavia and Sweden. The Luftwaffe took over the aircraft after the outbreak of war and employed limited numbers during the Battle of Britain, primarily in the reconnaissance role.
A total of 522 Do 17Zs were produced. In addition to Germany, operators of the Do 17 included Croatia, Finland, Hungary, Spain, Yugoslavia and Romania. Although its front-line career was comparatively brief, the distinctive “Flying Pencil” secured an enduring place among the aircraft associated with the Luftwaffe’s early wartime campaigns.
Frequently Asked Questions
What was the Dornier Do 17?
The Dornier Do 17 was a German twin-engined bomber and reconnaissance aircraft developed during the 1930s. It served in Spain and during the Luftwaffe’s early campaigns in Poland, Norway, France and Britain.
Why was the Do 17 called the “Flying Pencil”?
The aircraft was nicknamed Fliegender Bleistift, or “Flying Pencil”, because of its exceptionally long and narrow fuselage. The slender design had restricted its usefulness as a civil transport but contributed to its compact profile as a bomber.
How did the Do 17 become a military aircraft?
The Do 17 was originally developed by Dornier Flugzeugwerke as a high-speed civil transport for Deutsche Lufthansa. After Lufthansa rejected it, Flugkapitän Robert Untucht recognised its military potential and advocated its conversion into a fast bomber.
When did the Dornier Do 17 first fly?
The first Do 17 prototype flew in the autumn of 1934. Militarised prototypes followed during 1935, and the Do 17E-1 bomber and F-1 reconnaissance aircraft entered series production in early 1936.
When did the Do 17 enter Luftwaffe service?
The Do 17E and F began reaching front-line Luftwaffe units in early 1937. Both variants were deployed to Spain with the Condor Legion from the spring of that year.
What was the definitive Do 17 variant?
The Do 17Z was the definitive production version. It introduced a redesigned, fully glazed forward fuselage, additional crew space and stronger defensive armament. The Z-2 used improved BMW-Bramo 323P engines to restore the full 1,000 kg bomb load.
How fast was the Do 17Z?
The Do 17Z-2 had a maximum speed of 255 mph (410 km/h). It could reach approximately 370 mph (595 km/h) in a shallow dive and was particularly manoeuvrable at low altitude.
What armament did the Do 17Z carry?
The Do 17Z could carry as many as eight 7.92 mm MG 15 machine guns in the nose, upper rear cockpit, cockpit sides and ventral gondola. Its internal bomb bay accommodated a maximum load of 1,000 kg (2,205 lb).
What role did the Do 17 play during the Battle of Britain?
The Do 17 attacked British shipping, RAF airfields, industrial targets and London. It was especially effective in low-level terrain-following raids but became increasingly vulnerable when employed in large formations at medium altitude.
What happened during the Do 17 attack on RAF Kenley?
On 18 August 1940, nine Do 17s of 9./KG 76 carried out a low-level attack against RAF Kenley. The raid damaged or destroyed hangars, buildings and aircraft on the ground, but the German formations involved in the day’s operations suffered heavy losses.
How many Do 17s were lost during the Battle of Britain?
Official Do 17 losses during the Battle of Britain were recorded as 132 aircraft. On 15 September alone, the three remaining Dornier-equipped Kampfgruppen lost twenty aircraft destroyed and thirteen damaged.
What was the Do 17’s greatest strength?
The Do 17’s greatest strength was its low-altitude handling. Its manoeuvrability, strong structure and robust radial engines allowed crews to conduct fast terrain-following attacks more effectively than the Luftwaffe’s larger bombers.
What was the Do 17’s greatest weakness?
By 1940, the Do 17 was too slow to escape modern fighters and its individually mounted defensive guns provided inadequate protection. It also carried a smaller bomb load than the He 111 and lacked the speed and versatility of the Ju 88.
What was the Dornier Do 215?
The Do 215 was a development of the Do 17 powered by Daimler-Benz DB 601 inline engines. Originally intended for export, it was taken over by the Luftwaffe and used primarily for reconnaissance during the Battle of Britain.
How many Do 17Zs were built?
A total of 522 Do 17Z aircraft were produced, comprising approximately 500 Z-1 and Z-2 bombers and twenty-two Z-3 reconnaissance-bombers.