Shadow over the Atlantic

by Robert Forsyth

  Reconnaissance sorties against Gibraltar–England convoys met with good success, as did working with U-boats and also with bomber units. Cooperation, in principle, works. Deficiencies, which are caused in training, will be remedied.1

  Fischer also made clear in his report the need for FAGr 5 to be given an offensive capability in addition to its ‘passive’ reconnaissance and shadowing roles. In this regard he highlighted the Kehl/Strassburg radio-controlled guidance system for guided/glide-bombs. By the summer of 1943, two such weapons had reached the anti-shipping units of the Luftwaffe. The first of these was the SD 1400 X, codenamed Fritz X. Manufactured by Ruhrstahl, the SD 1400 X was based on an armour-piercing bomb with a 1,150-kg warhead, and was to be released from an aircraft at between 4000 and 7000 m. It then fell at near terminal velocity and was guided to the target by a bomb-aimer using the flare in the tail of the bomb as a marker. From 7000 m, the bomb took 42 seconds to reach its target, the bomb-aimer having control for the last 27 seconds.

  Initial trials of the SD 1400 had proved tricky when difficulties were experienced with the control of the free-falling bombs owing to their high velocities. These initial problems were overcome by early 1942, following which the bomb was trialled in the Mediterranean. The plan was to use the bomb with the He 177, but because of production delays with that aircraft, it was assigned for initial deployment on the Do 217K-2 of II. and III./KG 100. Once examples reached operational units, the Fritz X resembled the standard SD 1400 bomb, but with four stubby wings added.

  On 9 September, in the Mediterranean, nine Dorniers of III./KG 100 based at Istres attacked Italian warships which it was feared would be used by the Allies following Italy’s surrender. Each aircraft carried an SD 1400 X bomb and all were dropped west of the Straits of Bonifacio, with two making direct hits on the battleship Roma, which quickly broke in two and sank. Another bomb seriously damaged Roma’s sister ship, the Italia. Successful attacks would be carried out against British and American warships over the coming days.2

  The other weapon was the Henschel Hs 293 which carried a 500-kg warhead in the forward part of a small, cylindrical fuselage, itself forming part of a small ‘monoplane’ with rectangular wings and tailplane. The aft part of the missile contained the control gyroscope, radio receiver, batteries and battery-driven motor generator. After launch, a small Walter rocket motor accelerated the speed of the Hs 293 to around 600 km/h at an initial thrust of 600 kg, decreasing to 400 kg. Cutting out after about 12 sec, the bomb then coasted towards its target in a shallow dive guided by a bomb-aimer in the parent aircraft.

  As with the SD 1400 X, the first aircraft to deploy the weapon in action were the Do 217s of II./KG 100, which usually carried out attacks at night from 1000 m at about 320 km/h, at which the Hs 293 had a range of about 11 km, but the missile would also be used over the Bay of Biscay and the Atlantic by the He 177s of II./KG 40.

  The means of controlling and guiding both the SD 1400 X and the Hs 293 lay in the FuG 203/320 Kehl/Strassburg radio control system. Kehl had been developed by Telefunken and named after a district in Strassburg, the French/German city on the Rhine. The Kehl I transmitter was intended for use with the SD 1400 X, while the Kehl III was for controlling the Hs 293. The device transmitted orders as frequency modulations on a radio frequency carrier, with each weapon requiring a different set of four orders. The transmitter operated on one of 18 frequencies between 48.2 and 49.9 MHz, separated by 100 kHz. In the case of the SD 1400 X, these were right, left, up and down, while for the Hs 293 they were roll clockwise, roll anti-clockwise, pitch up and pitch down. The later FuG 203c Kehl IV, built by Telefunken and Opta, could be adjusted for use with either weapon. Before take-off the bombs would be pre-set to one of the frequencies with a corresponding setting made in the launch aircraft.3

  The system did suffer from problems associated with moisture and condensation, especially during long-range, high-altitude missions, but these were countered by incorporating a special heating system in carrier aircraft, which directed hot engine exhaust over the weapon controls. But this installation meant that the aircraft had to be specially fitted with both Kehl/Strassburg and the heating system, thus limiting the number of aircraft available.4

  Notwithstanding this, Fischer recognized the tactical value that Kehl would have for the Ju 290s of FAGr 5 in ‘armed reconnaissance’ missions. He noted:

  When, despite successful cooperation, success was not achieved, with the U-boats it was due to strong defensive measures taken by the convoys, and with the bomber units it was due to unsuitable weather conditions.

  Equipping the Gruppe with Kehl should lead to success in operations against convoys. Since shadowing stretches over several days (with ideal weather conditions), even with light forces (6–10 aircraft), considerable success should be attained.

  Fischer emphasized his point further by underlining, with some bitter irony, the first of the sentences that followed:

  The figure of reconnoitred tonnage to the figure of tonnage sunk speaks for itself.

  The [enemy’s] defence capability allows a sortie of 6–10 Ju 290 flying in formation. A tight formation of 6–10 Ju 290 is sufficient to form a strong defence against a Pulk [formation] of ‘Mosquitos’.

  The idea that Ju 290 missions equipped with Kehl strengthens the defence in areas of extreme range, is only partially correct. The defensive measures would increase anyway, and above all, when the Ju 290 is led successfully to a convoy together with Condor units equipped with Kehl. Ju 290 missions against convoys should take place where other bomber units, as a result of [lack of] range cannot be utilized and where U-boats, due to the defence situation, cannot operate.

  Quite apart from principles of leadership, with unit leaders one can set so much tactical understanding as a prerequisite, that these missions can be reduced to a minimum. The principal focal task – reconnaissance for U-boats – will in no way be affected by the carrying out of bomber operations [by Ju 290s]. The installation of Kehl equipment brings about a scarcely measurable loss in range. The Ju 290-Kehl aircraft has reached a developed stage and should be operationally ready by c.1.2.44.5

  Fischer’s mention of a ‘Ju 290-Kehl aircraft’ is most probably a reference to the new Ju 290A-7 variant, then under development at Junkers, which it was planned would be able to carry and deploy the new weapons technology.

  It is clear that Fischer saw the role of the Ju 290 not just in terms of lone reconnaissance and/or shadowing, or in conducting those types of mission with pairs or small formations of aircraft, but also as a strike-bomber equipped with Fritz X or Hs 293 bombs operating in larger formations at maximum range. He viewed the rationale that Ju 290s so equipped would attract greater enemy defence as illogical. Rather, the Ju 290 would be able to operate where the Fw 200 could not. In this, he would have found an ally in Dönitz and his staff.

  By December 1943, FAGr 5 was equipped with a single Ju 290A-2, four A-3, three A-4 and two new A-5 models.6 Oskar Schmidt recalled:

  Characteristics of the aircraft were good, easy to handle. Upon loss of one or two engines, the aircraft could still be flown well and permitted among other things, side-slipping. To ease their activities over a long a mission, the Kommandant [commander of the aircraft] and co-pilot had the assistance of an automatic Siemens three-axis steering [or control] device. The three dimensions could be switched-in/activated by means of three lever positions and thereby hold [the aircraft’s] attitude in flight.7

  Powered by four 1,700 hp BMW 801D engines, the five-aircraft Ju 290A-4 reconnaissance series (Fernerkunder) differed from the A-3 only in terms of lacking its internal transport configuration and some manufacturing processes. The Ju 290A-4 had accommodation for a crew of seven, including four ‘rest chairs’, as well as protective armour for the cockpit, weapons and engine areas. It came equipped with FuBl 2H receiver, FuG 101 radio altimeter, FuG 200 Hohentwiel ship-search radar and FuG 216 radar. Armament comprised a 20 mm MG 151/20 cannon in forward and aft low-profile dor
sal turrets and the tail position. Additionally, the right- and left-side waist positions each mounted a 13 mm MG 131 machine gun, while the forward ventral gondola housed another MG 151/20 (forward) and two 13 mm MG 131 machine guns (rear).

  Oskar Schmidt remembers that the aircraft’s armament transformed it into a ‘flying fortress’:

  Up top were two turrets (one directly behind the navigator’s position and another further back towards the end of the fuselage). The weapons in both turrets were 20 mm MG 151, fully automatic and fully rotatable. The gunner sat at his battle position and could move his guns electrically with a steering lever and, with a reflector sight, track the target. It was possible, if necessary, to mount a twin MG 131 at one of the three windows on the port and starboard sides. These weapons gave considerable firepower; the radio operator and flight mechanic would man these defensive guns. In an attack, range and lead-angle could be determined via the Revi, and the firing sequence would then be activated by means of a firing lever located on the control stick. Pre-set locks prevented hitting one’s own empennage. Each turret would be occupied by an air-gunner. The cockpit accommodated both pilots and the flight engineer. Then there were two radio-operators’ seats and a small, separate area for the navigator. All crew members could communicate over an intercom. Then came the built-in fuselage tank, which was passed to the side, followed by a cabin with four rest places, and near to the loading ramp was a cleverly built galley where the most suitable crew member could prepare refreshments and snacks as needed during the long flight times. At the end of the fuselage was a large dinghy with approproiate sea emergency equipment for 11 men, including SOS transmitter with kite antennae.8

  The Ju 290A-5 was essentially a modification of the A-4 with an improved forward dorsal turret and an extra oil tank to carry an additional 225 l, and other internal additions to the fuselage. Total equipped weight increased from 20,860 kg on the A-4 to 24,085 kg on the A-5, while fuel load went up by 4020 kg to 14,220 kg. The total weight of the Ju 290A-5 was 41,305 kg. A Flugzeug-Baureihen-Blatt (aircraft specification drawing) issued by the RLM on 1 September 1944 shows that it was intended to fit the A-5 with an ETC 2000 bomb rack under each wing to enable it to carry a weapon such as the SD 1400 Fritz X. Eleven examples of the A-5 would be built.

  But by the autumn of 1943, the Luftwaffe was aware of the shortcomings in its inventory. In January 1944, one report noted, ‘The fact that the [B-24] Liberator has proved superior to the Ju 290 serves as another reminder of the enormous strides German aircraft development must make to enable the Luftwaffe to achieve tactical successes in spite of numerical inferiority.’

  It was clear to the Luftwaffe what was needed in terms of long-range reconnaissance:

  The interior arrangements of aircraft could undergo examination when new developments occur. Operations carried out far over the Atlantic call for constant navigation. It therefore seems expedient not to burden the members of the crew responsible for this with other duties. The observer and the wireless operator would then be concerned solely with navigation, while the rear gunners would be responsible exclusively for observing a rear defence. Such an arrangement and the provision of the necessary accommodation would guarantee perfect identification of targets and effective use of armament.9

  Fischer was candid about the existing Ju 290 variants’ shortcomings and how Junkers could best serve Luftwaffe long-range reconnaissance in the coming years:

  Although the Ju 290, as opposed to all previously used types, offers an increase in range, it shows, in particular, that for reconnaissance west of Ireland, and for tasks on behalf of the B.d.U., the official flight range is insufficient. Increasing the take-off weight from 41 tonnes to 45 tonnes is intended, i.e. the installation of a second fuselage fuel tank holding 3,400 l and enabling an increase in range of around 400 km.

  By mentioning a prospective weight increase, it is most likely Fischer was referring to the planned Ju 290A-8, which had a capability to carry a 1930-kg ‘payload’, greater fuel and oil capacities over the A-5 as well as an allowance for more crew and special equipment.

  Fischer seemed equally unimpressed by the proposed Ju 290B series, on which work commenced (on the B-1) in late 1943; the design removed the Trapoklappe ramp. Powered by 2,000 hp BMW 801E engines, it was proposed to protect the aircraft with strong defensive armament in the form of nose and tail MG 131 Vierling turrets, each containing four 13 mm machine guns, two dorsal turrets with MG 151s and a ventral barbette with a further pair of such cannon. However, poor technical performance and difficulties with the pressurization system forced further development on the aircraft, as well as a proposed B-2 variant, to be abandoned by November 1944.

  Fischer’s view was that: ‘Equipping the Ju 290B with an MG 131 Vierling is no good. Our own aircraft will be shot down before the enemy aircraft comes within range of our own weapons.’ He further commented: ‘With regard to range, it is not thought that the Ju 290B, as opposed to the 45-t aircraft, will bring about a better performance, i.e. that it would attain a maximum tactical range of 2900–3000 km.’

  What Fischer really wanted was the Ju 390, the six-engined development of the Ju 290, the first prototype of which, the V1 Wk-Nr 3900001 GH+UK, had made its inaugural flight from the Junkers plant at Merseburg on 20 October 1943 with Flugkapitän Pancherz and Diplom-Ingenieur Gast on board. This massive aircraft, with a wingspan of 50.32 m (more than 8 m longer than the Ju 290), had been under development since mid-1942, and was seen as an even longer-range successor to the Ju 290 as a reconnaissance aircraft, as a carrier for ‘parasite’ fighters and even bombers, and as a long-range bomber and transporter. Powered by six BMW 801E engines, offering a range of 5860 km, with a crew of 10–12 men, the total equipped weight of the Ju 390 at take-off was 75 t, which included 30,400 kg of fuel, 1690 kg of oil, 8400 kg of ammunition and an allowance of 120 kg for an emergency dinghy and supplies. The aforementioned Flugzeug-Baureihen-Blatt of September 1944 lists the ‘Ju 390A-1’ as being equipped with an impressive array of radio and radar equipment and armament of three double-gun MG 151 Z (Zwilling – twin) sets and two MG 131s, plus four ETC 2000 racks for carrying offensive ordnance.10 According to Fischer:

  In order to take a decisive step for Atlantic reconnaissance, it is proposed that instead of the Ju 290B, mass production should go over immediately to the Ju 390. Likewise, as in the realm of high performance, the development of interim types of fighters should be abandoned in order to make an enormous leap, it would be purposeful in this case, in terms of range, to undertake the leap from the Ju 290A to the Ju 390. Besides the clear advantage of range, the Ju 390 possesses the following further advantages:

  (1) At great range, a longer time-span for shadowing.

  (2) Through great range, it can take increased defensive measures with alternating approach and return flights, taking into account greater flight distances. Constantly changing tactics negate enemy defensive measures. At the present time, in approach and return flights, the shortest approach path has to be selected on each occasion. Enemy defence is thus easily concentrated and will lead to further losses.

  (3) In the to-be-expected strengthening of [Allied] defensive measures in the Atlantic, the Ju 390 offers a decisive advantage in relation to its stability. It is possible, by means of armour, weapons and ammunition, to make the Ju 390 so stable that, in terms of range, it remains superior to the Ju 290B and in terms of stability, brings about decisive advantages.

  (4) Equipping it with Kehl over the furthest range is possible, and especially by internal suspension [i.e., storage and carriage of ordnance internally] only a small loss in range is to be expected.

  Set against the conditions in which they operated over the Atlantic, the question of armament was of paramount importance to the crews of FAGr 5. On this subject Fischer wrote:

  To increase defensive armament, the following development is proposed:

  The slow-flying Atlantikaufklärer begins and falls with its defensive armament. [Fischer’s
emphasis]

  It must be possible to so increase defensive armament that the aircraft is able to defend itself successfully against a swarm of enemy Zerstörer aircraft [long-range fighters – i.e., Mosquitos] by skilful flying. Air combat with an enemy Zerstörer aircraft has shown that at 2000 m range, fire was opened and that our own aircraft already received damaging hits at a range of 1500 m. It was only due to prevailing cloud cover that the aircraft escaped. This fact is unacceptable. The following weapons development is therefore considered to be correct:

  1st Phase: Immediate measures:

  Heckstand [tail gun position]: to be equipped with MK 103 [30 mm cannon] with greatest possible traverse of fire, in particular rearwards and upwards, as defence in low-level flight.

  Seitenlafetten [lateral MG 131 barbettes]: fully extendable and traversible with firing direction vertically to the rear, parallel to the aircraft longitudinal axis as with the Bv 222, Liberator, etc.

  2nd Phase: Heckstand MK 103. Seitenlafetten as under (1), except the MG 131 has 2-cm Zwilling [twin-gun set]

  3rd Phase: Heckstand MK 103. Seitenlaffetten 2-cm Illing;* B-1 and B-2 Stand (dorsal turrets) MG 151 Zwilling; all aircraft from Wk-Nr 180 [which became an A-5 (KR+LK) with 1./FAGr 5 as 9V+KH], A-Stand with 2-cm Illing, C-Stand MG 151 Z remote-controlled.

  4th Phase: For Ju 390A-Stand (nose) 3-cm Zwilling

  B-1-Stand (dorsal forward) 2-cm Zwilling

  B-2-Stand (dorsal aft) 3-cm Zwilling

  Heckstand (tail) 3-cm Zwilling

  Seitenlafetten 2-cm Illing

  C-Stand (lower fuselage, aft) 2-cm Zwilling remote-controlled

  For special tasks at extreme range, the armament can be reduced in favour of increased fuel load; escort protection on approach and return flights by strongly armed Ju 390s for this aircraft will need to be secured at all times.

  There had also been sufficient time for the crews of FAGr 5 to assess the working efficiency and functionality of the Ju 290. Fischer found concern particularly with the navigator’s area within the aircraft: