DORNIER DO 217 OVERVIEW

Versatile bomber, nightfighter, recce-plane which also carried the first guided aerial weapon.

The Dornier 217 was the first new German reconnaissance bomber to enter large‑scale service with the Luftwaffe after the beginning of World War II. It began its operational life during the last months of 1940 flying clandestine reconnaissance missions deep into Russia‑with which Germany was, at that time, ostensibly still on friendly terms. During 1942 and 1943 the Do 217 inflicted most of the damage caused by German air attacks on Britain. At the same time, a few of these aircraft operated as night fighters against the RAF night attacks on the Reich.

In the summer of 1943‑as the performance of the Dornier was beginning to fall short of what was required by frontline units‑the type underwent a new lease of life. It was modified to carry radio‑guided missiles. These were the first such weapons ever launched operationally from aircraft. In its new role the Do 217 scored some spectacular early successes. Finally, however, the overwhelming Allied fighter superiority on all fronts caught up with the bomber units operating the Do 217. From the beginning of 1944 almost all attempts to operate these aircraft against worthwhile Allied targets‑by day or by night, with or without missiles‑resulted in the same debilitating losses. By late summer 1944, after 1,887 examples had been delivered, the Do 217 had been all but discarded from front‑line service in the Luftwaffe.

A twin‑engined high‑winged monoplane with twin fins and rudders, the Dornier 217 was of conventional all‑metal construction. It carried a crew of four‑pilot, observer, radio operator/air gunner and ventral gunner. The observer, as well as navigating the aircraft, was responsible for bomb aiming and firing the nose‑mounted flexible gun on the rare occasions it was used. The positioning of the crew close together in the nose made for efficiency. During operations, a lot of information could be conveyed by signs or by pointing. This minimized the distractions caused by ‘intercom natter’.

The most used variant of the Do 217 was the E model. The forward‑firing gun armament usually fitted was a fixed 15mm cannon and a flexible 20mm cannon. The former was fired by the pilot and the latter by the observer. For defense there was a 13 mm machine‑gun in the power‑operated dorsal turret, four rifle‑calibre machine‑guns firing from the side windows of the crew compartment. Another of these weapons (later replaced by a 13mm gun) was mounted in the ventral position. Four 500kg bombs, or four containers each with 140 1‑kg incendiary bombs, or two 1,000kg sea mines were the typical loads carried in the bomb bay. There was also provision for the plane to carry a single F5B torpedo internally. But it seems that the aircraft never carried this weapon operationally.

Like other German bombers, the crew positions in the Do 217 were well protected with armor. The pilot had an 8.5mm‑thick steel plate shield behind his seat, 5mm‑thick steel under his seat pan and a further 5mm‑thick plate above and behind his head. Behind the crew compartment was a semi‑circular transverse armored bulkhead 8.5mm thick, with 5mm plates at the sides. As was normal German practice, the compartment for the inflatable life raft in the rear fuselage was protected with 5mm plate at the sides, top and bottom, and 8.5mm plate at the rear.

Also, as was usual for German bombers, self‑sealing fuel and oil tanks were fitted in the Do 217. This was a vital safeguard. The ignition of petrol or oil leaking from tanks caused major aircraft losses during World War II. The standard German self‑sealing tank comprised an inner shell of compressed cellulose fibre around which was a layer of thick leather, a layer of thick crude rubber, two layers of thin rubber sheet and an outer layer of thick vulcanized rubber. Altogether, the wall of the tank with its self‑sealing layer was about half‑an‑inch thick. When bullets or shell fragments hit the tank they usually punched their way clean through the walls and out the other side. But when the petrol or oil leaked out of the holes and reached the crude rubber a chemical reaction was set up. This caused the crude rubber to swell‑sealing the holes. During the sealing process a small amount of crude rubber was dissolved into the petrol. This caused some contamination, but not enough to seriously affect the engines. They continued to function with little loss of efficiency.

A further factor which helped reduce the vulnerability of the Do 217 was the fitting of air‑cooled engines. Because there was no coolant to leak away, air‑cooled engines were about half as likely to be stopped by battle damage as were liquid‑cooled engines. The 1,580hp BMW 801 14‑cylinder radials of the Do 217E employed direct fuel injection‑a useful feature because the engines continued to operate under negative‑G conditions. This was in contrast to the float‑type carburetors fitted to British fighters during the early war period. These cut out when their pilots tried to follow German aircraft bunting over into a dive.

Pilots who flew the Do 217 recall that it was a stable machine with good handling characteristics at the medium and high-speed ends of its performance range. Due to its high wing loading, however, the landing speed was also high. And the undercarriage frequently proved unable to take the demands made on it during a heavy landing.

With a maximum all‑up weight of about 17 tons, a range of 1,430 miles and a top speed of 320mph, the Dornier 217E’s closest equivalent was the American B26 Marauder. This had a similar weight and performance and was also designed with a high wing loading.

The Dornier 217 was designed as a replacement for theearlier Do17 medium bomber. The new plane was to have a higher performance and be able to carry a heavier bomb load, and it had to be stressed and equipped for dive-bombing attacks. The first prototype of the Do 217 made its maiden flight in August 1938. But its handling characteristics were bad and the prototype crashed the following month, killing both members of the test crew. By early in 1939 three more prototypes were flying. The problem of improving the basic handling characteristics of the Do 217 proved relatively simple to overcome. But that of making such a large aircraft into an effective dive-bomber proved beyond solution. Following lengthy trials with different types of air brake, during which some aircraft were lost and others overstressed during the pull‑out maneuver the dive-bombing attack was deleted from the aircraft’s repertoire.

The first Do 217 to enter service with the Luftwaffe was the E variant. Late in 1940, 10 of the first production aircraft were issued to the Second Staffel of Fernaufklaerungsgruppe 11‑a long‑range reconnaissance unit which soon afterwards became involved in the clandestine high‑altitude flights over Russia. During these missions the Dorniers carried two vertically‑mounted long‑focal‑length cameras. They took the photographs of the Soviet defenses which were to play an important role when the Germans invaded Russia in June 1941.

The first bomber unit to receive the Do 217 was the Second Gruppe of Kampfgeschwader 40, based in France, which received its complement (a Gruppe had a nominal strength of 30 aircraft) during the spring and summer of 1941. At first the aircraft were employed on minelaying missions against British harbors and shipping lanes and, less often, in direct attacks on shipping. Later in 1941 the three Gruppen of Kampfgeschwader 2 moved to France, also equipped with the new bomber.

HITLER’S DEMAND FOR RETALIATION

By this time, large‑scale German air attacks on Britain had come to a halt with the transfer of the bulk of the bomber force to the Eastern front. Do 217s concentrated on anti‑shipping work. However, this quiescent period came to an abrupt halt following the powerful RAF attack which destroyed much of Lübeck on 28 March. Hitler demanded retaliation and in the month that followed German bombers, for the most part Do 217s of KG2, launched two sharp attacks on Exeter and two more on Bath. On the very night that Bath was under attack, however, the RAF was engaged in a series of four destructive raids on the German town of Rostock. Hitler was apoplectic at this affront and in an impassioned speech he spoke of taking a copy of Baedeker’s guidebook and marking off each British city as it was razed to the ground. Because of this the series of attacks became known in Britain as the Baedeker Raids. During the late spring of 1942, Bath, Norwich, York, Cowes, Hull and Poole, Grimsby and Exeter, all suffered varying degrees of damage. But the German bombers had to penetrate the increasingly powerful British night fighter and gun defenses, and suffered heavy losses. The series of attacks ended with three raids on Birmingham and one on Hull at the end of July, which cost the Luftwaffe 27 aircraft and caused only minor damage.

Following this battering Kampfgeschwader 2, which was now the only bomber unit operational with the Do 217, was withdrawn from operations over Britain to make good the losses suffered. But the respite was to prove short lived. On 19 August Allied forces launched the large‑scale seaborne raid on Dieppe and virtually all operational Luftwaffe units in France and Belgium went into action in defense of the port. Operating by day, the Dorniers came up against powerful standing patrols of Spitfires. The Germans suffered catastrophic losses. Out of a total of about 80 planes committed by KG2‑many of them flown by trainee crews‑20 were shot down. Having started the year with an average strength of 88 trained crews, by September 1942 KG2 was down to 23.

KG2 took little part in operations for the rest of the year. At the end of 1942 two improved versions of the Do 217 entered service‑the K and the M. Both of these had more powerful engines and a redesigned low‑drag nose profile. The K model was fitted with the new BMW 801 D radial engine developing 1,700hp, while the M employed the similarly powerful liquid‑cooled Daimler Benz 603 in‑line. The two new variants were about 20mph faster than the earlier E model. In addition to their greater speed the new Dorniers had the advantage of carrying tail‑warning radar to reduce the chances of surprise fighter attack at night, and radio altimeters to make possible a low‑level penetration of defenses at night or in poor visibility.

With these technical improvements the revitalized KG2 recommenced its operations over Britain early in 1943.

During these night attacks the Do 217s exploited every possible stratagem to avoid the attentions of the defenses: a low‑level approach, climbing to medium level to bomb then letting down to low level for the withdrawal; a high-level approach, bombing during a shallow descent and making the withdrawal. Since the bombers’ targets were rarely more than 50 miles inland, these methods helped a lot to keep the German losses down. Even so, the defenders were able to take their toll. During March 1943 alone, Kampfgeschwader 2 lost 23 complete crews.

Typical of the German raids on Britain in the summer of 1943 was that by 91 planes on Portsmouth, on 15 August. The Dornier 217s of the First and Third Gruppen of KG2 operated from St Andre and Dreux respectively, both near Paris. After take‑off the bombers funnelled together over Cap D’Antifer near Le Havre and headed NW across the sea flying at an altitude of 200ft, beneath the prying beams of the British radar. At a point 24 miles south of Brighton the bombers commenced their climb, aiming to arrive over Portsmouth at 15,000ft. The actual attack was delivered soon after 0100 on the morning of the 16th. It lasted about 10 minutes. Afterwards the bombers turned to port and withdrew along the route they had come. Such a low‑level approach to a coastal target should have given the raiders the advantage of surprise. But the RAF night‑fighters proved their alertness by shooting down five of the attackers ‑all Do 217s. Four of the bombers fell to the Mosquitoes of No 256 Squadron, based at Ford near Bognor, Sussex.

The Dornier 217 was involved in the resurgence of air activity over Britain in early 1944. But the units operating the type represented less than a fifth of the force involved. By that time the performance of the Do 217 was not good enough to enable it to survive without heavy losses in the face of the powerful defenses.

NIGHTFIGHTER

During 1942 and 1943 a total of 364 J and N nightfighter versions of the Dornier 217 were delivered to the Luftwaffe. In addition to Lichtenstein radar equipment with a range of 21 miles, these aircraft carried a forward‑firing armament of four 20mm cannon and four rifle‑calibre machine‑guns. The High Command thought that the long endurance of the Do 217 would make it a useful addition to the German night fighter force. But it proved unpopular with the front‑line units. It was too heavy on the controls and had too low a rate of climb to be very effective against the RAF night bombers. After a short time the majority of the Do 217 night fighters were relegated to training units. About 30 were turned over to the Italian Air Force.

In the summer of 1943 some Dornier 217s were modified to carry air‑launched guided missiles‑the first such weapons ever to be used in action. There were two quite different types of missile, though subsequent accounts have frequently confused them or treated them as one.

GUIDED MISSILES

The first of the guided missiles to enter service was the Henschel 293 glider‑bomb. This weapon looked like a small aeroplane with a wingspan of just over 10ft. Prior to launch it weighed a little over 2,000lb, 1,100lb of this being the warhead. After release from the parent aircraft the rocket motor under the missile fired‑carrying the weapon to a speed of about 370mph. Then the motor cut out and the missile coasted on in a shallow dive, accelerating slowly towards its target. The range of the missile depended upon the altitude of the parent plane at the time of release. A typical operational range was five miles, for which the aircraft needed to be at 4,500ft. In the tail of the missile was a bright tracking flare. This allowed the observer in the parent aircraft to follow its movements. The observer operated a small joy‑stick controller, the movement of which fed the appropriate up‑down‑left‑right impulses to the guidance transmitter, which in turn radiated them to the missile. Here, they were converted into control movements for the ailerons and elevators. The observer only had to steer the tracking flare until it appeared to be superimposed on the target and hold it there until the missile impacted. The Henschel 293 was a low‑speed weapon compared with a normal‑gravity bomb and as a result had little penetrative ability. It was intended mainly for use against merchant ships and more lightly armored warships.

The glider bombs were used in action for the first time on 25 August 1943.Fourteen Do 217s of the Second Gruppe of Kampfgeschwader 100 attacked a Royal Navy U‑boat-hunting group off the NW tip of Spain. An observer on the sloop HMS Landguard later reported, after the aircraft had formed up off her starboard quarter at a range of about six miles

‘EXACTLY LIKE AN AIRCRAFT’

‘A pall of smoke forming into a streamer appeared from the leading aircraft. At the time of firing the aircraft were on a reciprocal course to the ships, well out on the beam. The projectile was seen for some time apparently near the aircraft, but this was probably due to the fact that it was coming towards the ship at a constant bearing. Flashes were seen coming from the aircraft at about the time of the firing (almost certainly this was due to the tracking flare lighting up) but neither smoke nor flame from the projectile during the later stages of its run . . .. The projectile then banked exactly like an aircraft and set course towards the ship, descending at an angle of about 15° or 20°. When about two cables from the starboard quarter the bomb appeared to be pointing straight at the ship. Then it banked to starboard and lost height rapidly, falling in the sea one hundred yards off Landguard’s starboard quarter and exploding on impact.’

Two further bombs were aimed at Landguard, both of which exploded clear of her.

The only damage inflicted during the action was to the sloop HMS Bideford. A near miss caused splinter damage to her port side, holing her stores, Asdic compartment and forward mess deck and causing some flooding. She was able to continue in action, but was later in dock for a month being repaired.

Two days later‑27 August‑the Dorniers again attacked British warships off the NW tip of Spain. This time the victims belonged to the 1st Escort Group comprising the destroyers Grenville and Athabaskan, the frigates Jed and Rother and the sloop Egret. Soon after 1200 the force of 18 bombers was sighted coming in from the north. The warships were heading southwards in a line‑abreast formation searching for U‑boats. The commander of the force, Captain Godfrey Brewer in Egret, immediately ordered ‘Repel Air Attack’. All ships went to action stations and ‘ increased speed. The ships swung into two columns of two ships in line ahead‑with two miles between columns. With her powerful AA armament of eight 4in guns, Egret was to move across the rear to support whichever column was threatened.

The attack began with four Dorniers flying along the ships’ port side. When they came within gun range Athabaskan and Egret opened fire. But the bombers held their course and each launched a glider bomb at Athabaskan. ‘ The first three missiles fell harmlessly into the sea, but the fourth continued on and struck and destroyed near the base of her ‘B’ gun turret. The bomb smashed straight through the superstructure, shedding its wings and body in the process. The warhead finally detonated just clear of the ships’ starboard side abreast the forward end of the bridge. The explosion caused severe splinter damage. ‘B’ turret shell‑room, two fuel tanks, the torpedomen’s mess and lower power and gyro room were all flooded. The blast caused the fires in the boilers to flash back into the boiler rooms. This resulted in a minor oil fire. Athabaskan’s engines stopped. She slid to a halt.

BITTER FRUITS OF GALLANTRY

Meanwhile the German bombers were forming up on the starboard side and Egret departed to support the column there. But her gallantry was to bear bitter fruit. It was on her that the German crews now concentrated their attack. Within a short time seven glider bombs were streaking towards the sloop. The commander of Egret, Commander John Waterhouse, reported afterwards:

Several rocket bombs were now heading for Egret and I increased to full speed and put the wheel hard to starboard in an endeavour to point them and present the smallest possible virtual target. Two bombs passed close astern and a third was either hit by Oerlikon fire or else fell into the sea within thirty feet of the starboard side amidships.

After this escape a report was received from the engine room that all was well below and I assumed that any damage sustained was superficial. The ship was momentarily steadied on a west‑north‑westerly course with her main armament engaging the enemy, when two more bombs were reported approaching from just before and just abaft the starboard beam. I did not see the one approaching from aft, which I believe missed, but I was able to observe carefully the behaviour of that before the beam. Swinging fast under full starboard rudder the ship would normally have brought the bomb, which was flying level about fifteen feet above the water, within 30° of the ship’s bow and the bomb should have passed down the starboard side. In the event the bomb banked sweetly and turned smoothly to starboard like a well‑piloted fighter aircraft and so continued to head straight for the bridge . . ..

The missile struck Egret near her forecastle deck, and the warhead continued on into the ship before detonating. The resultant explosion, whose force was probably compounded by the detonation of one of the ship’s magazines, almost certainly blew out a large area of plating on Egret’s port side.

She listed badly to port. Within about 40 seconds of the explosion she had capsized completely. She floated bottom up for over an hour before sinking. Only 36 men survived out of a complement of 188. So it was that Egretgained thedubious distinction of being the first ship ever to be sunk by an air‑launched guided missile.

The crew of Athabaskan were able to effect temporary repairs to their engines and the destroyer returned to Britain under her own steam. Permanent repair work kept her out of action for over two months.

From German records it would seem that Leutnant Paulus and Hauptmann Vorpahl, respectively, had captained the Dorniers which sank Egret and damaged Athabaskan. It must be said, however, that the total of only two hits for an expenditure of 25 glider bombs during the attacks on 25 and 27 August was hardly impressive. During a subsequent investigation into the causes of the missile failures‑held at the bombers’ base at Bordeaux/Merignac‑‑it was discovered that several of the Dorniers had had their missile control transmitters sabotaged in a very cleverwayso thatnormal ground tests did not reveal the fault. The SS conducted a full investigation, but the culprit was never found.

While the Second Gruppe of Kampfgeschwader 100 was operating with its glider bombs, the Third Gruppe was preparing to go into action with a quite different type of missile. This was the Fritz‑X guided bomb‑‑a high‑velocity weapon designed to pierce the heaviest armor. In appearance the Fritz‑X resembled an ordinary bomb, except that it carried four stabilizing stub‑wings mid‑way along its body. It weighed 3,100 lb and was unpowered. Released from altitudes around 20,000ft, it fell under gravity to reach an

impact velocity close to that of sound. In the tail of the bomb was a tracking flare, and after release the missile was guided down to its target in a similar way to the glider bomb. Since the Fritz‑X had to be released from high level if it was to reach the necessary impact velocity, III./KG 100 received the high‑flying K2 version of the Dornier 217. This model was similar to the normal K type‑except that its wingspan was 19ft wider.

For the Third Gruppe of Kampfgeschwader 100 the big chance came on 9 September. The Italians capitulated and their battle fleet made its dash to Malta to surrender. The main body of the fleet sailed from La Spezia in northern Italy and included the modern battleships Roma, Italia and Vittorio Veneto. Early that afternoon Major Bernhard Jope, the commander of Kampfgeschwader 100, led a striking force of eleven Dorniers off the ground at Marseilles/Istres. Each aircraft carried a single Fritz‑X under its starboard wing, close to the fuselage.

The bombers caught up with the Italian warships off the Straits of Bonifacio‑between Sardinia and Corsica. The German crews broke formation and attacked individually–aiming their missiles at the ships twisting below. After releasing the Fritz‑X each pilot throttled back his engines and climbed through 1,000ft. This brought the aircraft in line with the missile and the target during the final stage of the missile’s trajectory. It was now possible to guide the Fritz‑X on to the target. Apart from being essential for the control of the missile, this maneuver produced the useful bonus of throwing off predicted AA fire from below.

One of the first bombs scored a near miss on the Italia, temporarily jamming her rudder. A few minutes later another scored a direct hit on Roma, on her deck near the starboard side abeam her after funnel. The missile punched its way straight through the ship and exploded immediately underneath the hull, wrecking her starboard steam turbines and causing some flooding. Severely shaken, Roma’s speed fell to 16 knots and she began to list to starboard. A little later a second bomb struck Roma. This was almost certainly released from the Dornier flown by Oberleutnant Heinrich Schmetz with Feldwebel Oscar Huhn as observer. This missile hit the ship squarely just in front of her bridge and pierced deep into her vitals and then detonated. The explosion‑its effects worsened by being confined inside the armored structure‑knocked out the remaining steam turbines and started an uncontrollable fire which raged through to the forward magazine. With a violent explosion the battleship snapped in two like a jack‑knife, and sank. Only 622 officers and ratings survived, out of her crew of nearly 2,000.

Shortly after the second bomb hit Roma, Italia took a Fritz‑X on her bow, which blew a large hole. She took on about 800 tons of water. In spite of this, the battleship was able to limp to Malta unaided.

In the months that followed, the Dornier 217s of Kampfgeschwader 100 scored other successes. A direct hit and two near misses with Fritz‑X bombs on the battleship HMS Warspite put her out of action for seven months; a single Fritz‑X hit on the cruiser HMS Uganda, which required repairs lasting over a year. At the same time, Henschel 293 glider bombs sank the cruiser HMS Spartan and several destroyers. But the Allies proved able to take the measure of the new threat. Strong fighter patrols were maintained over all future concentrations of shipping. From the spring of 1944 it was rare for the missile‑carriers to reach their targets. They usually suffered debilitating losses whenever they tried. During the invasion of Normandy in June 1944 the Allied shipping not only enjoyed powerful fighter cover, but some of their number carried special transmitters which emitted jamming on the German missile‑control frequencies blotting out the radio command signals. As a result of these countermeasures, the missiles were virtually useless.

The German failure to contain the Allied invasion of Normandy coincided with the success of the Allied strategic bombing offensive against the German oil industry. This led to a crippling shortage of aviation fuel. One result of this was that the Luftwaffe bomber force was reduced to a shadow of what it had been. Most of the units were disbanded, their men being sent to the fighter units or into the army. A few Dornier 217s continued in use until the end of the war; but the majority of those that survived their bomber units ended their days in aircraft parks, where they swelled the scores of strafing Allied pilots.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.