Focke-Wulf Fw 190, Part 2

Battling the Viermot

A captured Fw 190A-8/R2. US Army Air Forces
[Public domain], via Wikimedia Commons
I’m back again with the second part of this series about the Focke-Wulf Fw 190 – the Luftwaffe’s forgotten fighter. In the first part we covered the genesis of the Fw 190 and how the RLM (German Air Ministry) wanted another fighter to supplement the Messerschmitt Bf 109. We looked at the unusual choice of using a radial engine for the Fw 190 and how when it it first appeared over the English Channel in 1941 it totally outclassed the contemporary Spitfire Mk.V. We looked at the British response and the rush to develop the Spitfire Mk.IX and the Fw 190’s own evolution through to the A-5 variant of 1943. The A-5 was the last of what’s considered the early Fw 190 variants and beginning with the A-6 the aircraft took a different path as new missions became prioritised.

Once again I’m going to stress just how good the Fw 190A was in 1941/42 compared to the contemporary RAF fighters. In 1942 two major operations took place during which the Fw 190 proved how much better it was than the Spitfire Mk.V

From 11th to 13th February 1942 the Germans conducted Unternehmen Zerberus (Operation Cerberus), probably better known as “The Channel Dash”. The battleships Scharnhorst and Gneisenau and the heavy cruiser Prinz Eugen would relocate from Brest on the French Atlantic coast to naval bases in Germany in preparation for an expected British naval invasion of Norway. Instead of routing north around Scotland and back down though the North Sea where they would be vulnerable to British air attack for several days and well out of range of Luftwaffe air cover the Germans decided to instead route the capital ships straight through the English Channel and through the Strait of Dover. The man responsible for planning the Luftwaffe’s air cover was the recently promoted General Der Jagdflieger (General of Fighters) Adolf Galland. He staked his career on the superiority of the Fw 190 when he personally lobbied, successfully, for the transit of the Strait of Dover to take place during daylight hours when he reasoned his fighters could be most effective. He was right. The German fighters, including the Fw 190s of Jagdgeschwader (Fighter Wing) 3 and 26 maintained air superiority over the Channel and the British air attacks were both unsuccessful and very costly. Ultimately Unternehmen Zerberus proved to be a tactical victory for the Germans, but a strategic error as the capital ships were now cut off from the Atlantic where they could have done more for the German war effort. However, that’s a story best told by another.

On 19th August 1942 the Allies mounted Operaton Jubilee, or the Dieppe Raid. The air battle over Dieppe saw the 120 fighters of JG3 and JG26 face of against sixty squadrons of Spitfires, Hurricanes and Mustangs. Once again the Fw 190 demonstrated its superiority, with the Luftwaffe losing twenty six Fw 190 in return for ninety four Allied fighters shot down that day. Through sheer weight of numbers the RAF was able to maintain very local air superiority over Dieppe, but failed to deliver the knock out blow to the Luftwaffe in France it had hoped for.

The first American heavy bomber units arrived in England in the spring of 1942. Initially at least, their targets were less heavily defended ones in France and were escorted, often by RAF fighters. The initial success of these raids somewhat allayed British fears of the Americans suffering heavy losses during daylight bombing operations as Bomber Command had earlier in the war. However, in January 1943 the Allies agreed at the Casablanca Conference to begin a coordinated bomber offensive against Germany. The Allies were already thinking ahead to the invasion of Europe and knew air superiority would be vital to its success. Thus, Operation Pointblank was conceived to target and destroy Germany’s fighter production. The Americans would bomb Germany by day, the British by night. Operation Pointblank commenced in the summer of 1943.

The Boeing B-17 Flying Fortress
See page for author [Public domain], via Wikimedia Commons
The Consolidated B-24 Liberator. USAAF
[Public domain], via Wikimedia Commons
The two heavy bombers available to the Americans were the Boeing B-17 Flying Fortress and the Consolidated B-24 Liberator. On paper at least, the Liberator was the better bomber having a longer range and a heavier bomb load. The Flying Fortress’ name though, was no accident. The B-17F in service when Pointblank commenced was defended by no less than ten .50 calibre heavy machine guns and the B-17 itself was incredibly tough and able to withstand serious damage and keep flying. What’s more, the American doctrine was to fly in close formations called a combat box which would put literally hundreds of heavy machine guns in the same piece of sky covering every direction a Luftwaffe fighter might attack from.

The B-17 was renowned for its ability to take a lot of damage and still bring its crew home. US gov
[Public domain], via Wikimedia Commons

These combat box formations were a very tough nut to crack for the Luftwaffe. First they’d have to brave the fire of hundreds of heavy machine guns and once they were within range to open fire themselves they would often find their own armament simply wasn’t heavy enough to reliably bring down what the Luftwaffe pilots dubbed the Viermots, literally “four engines”. Initially the Germans fell back on their Zerstörers (destroyers). The Zerstörers were an idea which went back to before the war. Twin engine heavy fighters with a very powerful armament. The most common of these was the Messerschmitt Bf 110, but also included the likes of the Junkers Ju 88 (initially a bomber but so versatile was the design if fulfilled many roles during the war including ground attack, night fighter and Zerstörer), the awful Messerschmitt Me 210, and proving you can’t polish a turd, the only very slightly better Me 410.

The Combat Box formation was intended to provide mutual protection and concentrate the defensive firepower of the heavy bombers to cover attack from any direction
Anynobody [CC BY-SA 3.0], via Wikimedia Commons
The Me 410 Zerstörer was developed from the dreadful Me 210. Plagued with abysmal aircraft handling it was deeply unpopular with its pilots
Mike Freer – Touchdown-aviation [GFDL 1.2 or GFDL 1.2], via Wikimedia Commons

Zerstörers have a problem though. They are horribly vulnerable to far more agile single engine fighters. The Germans learned this with the Bf 110 during the Battle of Britain. So poor was their performance against the single engine Spitfire and Hurricane that by the end of the battle the vaunted Zerstörers needed fighter escorts of their own. This is a big reason why the RAF never adopted twin engine heavy fighters in a big way, the Bf 110 experience during the Battle of Britain highlighted what a flawed concept it was. So whilst the Zerstörers were somewhat successful against unescorted bombers, the Luftwaffe realised it needed something better.

Enter the Stürmbock, or “battering ram”.

The Germans realised what was needed was a single engine fighter which was hardened against the defensive armament of the Viermots, but which also had the hitting power to reliably bring the big, tough American bombers down. They looked at the Messerschmitt Bf 109 and shook their Teutonic heads. Willi Messerschmitt’s thoroughbred race horse was too light and flimsy. They looked at the Fw 190 and smiled. Kurt Tank’s Dienstpferd, his cavalry horse was built sturdy and tough from the very beginning. This would be a suitable Stürmbock.

The first Stürmbocke were based on the Fw 190A-6. The baseline A-6 was itself designed to better deal with American heavy bombers. A redesigned wing structure capable of accommodating heavier armaments was introduced and the wing mounted outboard MG FF/M cannons were replaced with 20mm MG151/20E cannons which were faster firing with a higher muzzle velocity. The first Stürmbock variant was the A-6/R1 which replaced the outboard wing mounted 20mm cannons with a pair of pod mounted twin cannons of the same type, bringing the total armament up to six 20mm cannons and two 7.9mm machine guns.

This was soon followed by the A-6/R2 which replaced the outboard wing mounted 20mm cannons with 30mm MK108 cannons. The MK108 was a devastating weapon and just a few hits could bring down a Viermot very effectively.

The Rheinmetall-Borsig MK108 30mm cannon found its way into several late war Luftwaffe fighter types including the Fw 190, Bf 109 and Me 262. It proved devastatingly effective against the American heavy bombers
Goshimini [CC BY-SA 4.0], via Wikimedia Commons

The A-6/R6 added a pair of W.Gr.21 launchers under the wings. These were 210mm calibre rocket mortars which were set on a timed fuse. The idea was to fire these into the bomber formation and the resulting explosion and shrapnel would help break up the combat box formation and make the individual bombers easier to kill.

In November 1943 the A-7 entered production. The major change in this variant was the replacement of the 7.9mm MG17 machine guns in the cowling with 12.9mm MG131 heavy machine guns. The A-7 was produced in R1, R2 and R3 variants which had various configurations of 20mm and 30mm cannons installed. One A-7 was also used to test the “Droppelreiter” fuel tanks. These were streamlined fuel tanks fitted to the top of the wings, meant to increase fuel capacity without adversely effecting the drag or aerodynamic qualities of the aircraft. The idea wasn’t adopted by the RLM. The Droppelreiter was the forerunner of what we today call a Conformal Fuel Tank, or CFT and are very popular options on modern fighter aircraft.

Only 80 A-7 variants were produced before it was superceded by the A-8 in January 1944. The A-8 would go on to be the most produced variant of the Fw 190. The aircraft was powered by either a standard BMW 801 D-2 engine or a BMW 801 Q(TU) powerplant. This latter variant was a “Triebwerksanlage” or unified powerplant installation. The entire powerplant including engine, propeller, turbocharger and cowling were all designed as a single piece removable installation. This would allow aircraft in the field to have their entire powerplant quickly removed and swapped for service or repair. The A-8 also featured a thicker armour on the cowling and even thicker armour on the oil cooler ring at the front of the cowling. New radios were fitted and there were options for various engine power boost systems (more on those in the next part of the series). Like the other late war Fw 190A variants the A-8 was produced an a range of sub variants:

The Fw 190A-8/R2 had the outer wing 20mm cannons replaced with the 30mm MK108. This was the most widely produced of the Stürmbocke and 800 were built by Fieseler at their plant in Kassel.

The Fw 190A-8/R4 had a GM-1 nitrous oxide boost for the engine. Again, more on those systems in the next part.

The Fw 190A-8/R8 had substantial armour added to the cockpit area to protect the pilot.

Fw 190A-8/R2 Stürmbock. Note the larger calibre MK108 cannon just above the undercarriage leg compared to the smaller cannons mounted in the wingroot
Fabrice742 [CC BY-SA 4.0], via Wikimedia Commons

In September 1944 the Fw 190A-9 entered production. The major change here was an improved BMW 801S engine delivering 1,970hp. Various changes to the cowling were also made including a more efficient cooling fan in front of the engine and thicker armour on the engine oil system. A new blown canopy with better visibility was also fitted. The A-9 also featured the same factory and field modifications as the A-8. Production of the A-9 was in parallel with the A-8, but was heavily effected by unreliable supply of BMW 801S engines due to Allied bombing.

It was originally intended the A-9 would use the new 2,367hp BMW 801F engine, but this new powerplant was not ready in time. Focke-Wulf were working on the Fw 190A-10 when the war ended. This would have featured the BMW 801F engine and a new, larger wing.

How did the Stürmbocke fare in combat? The Germans still lost the war is the simple answer. The more detailed answer is they did quite well, when they had a chance to have a go at the bombers. The problem for the Germans was as the war progressed this became increasingly difficult.

On 17th August 1943 the US 8th Army Air Force launched a dual raid on Regensburg and Schweinfurt. In accordance with Operation Pointblank the targets were the Messerschmitt plant at Regensburg and a ball bearing factory at Schweinfurt. A force of 376 B-17s were launched esorted by P-47 Thunderbolts and RAF Spitfires. The Thunderbolts and Spitfires only had the range to escort the bombers part of the way. The targets were deep in Germany and the bombers would be unescorted for much of the way into and out of their targets. The B-17s were torn into by around 400 Luftwaffe fighters including Fw 190 Stürmbocke. The result was 60 bombers lost, nearly a hundred badly damaged and well over 550 American airmen missing. This was a devastating blow. Such losses were totally unsustainable. The Merlin engined P-51B/C Mustangs which could escort the bombers deep into Germany wouldn’t begin to arrive until the winter of 1943/44, and contrary to popular belief, things still didn’t change much.

Nevertheless the arrival of the Mustangs wasn’t good news for the Stürmbocke. Remember in the first part of this series I kept stressing the BMW 801 powerplant of the Fw 190 really took a serious performance hit in the thin air above 20,000ft. The Viermots would operate well above this altitude, and the Stürmbocke were very heavily burdened with all their extra armour and armament. The heavy Stürmbocke were operating at the very worst altitude, and the Mustangs were operating at altitudes where they were at their very best. If a Stürmbock pilot found himself tangling with a Mustang he would be at a distinct disadvantage.

The German response was to develop a new tactic called Sturmgruppe (attack groups). These were mixed fighter formations. Stürmbock Fw 190s would join up with Messerschmitt Bf 109s, usually G variants with their Daimler Benz DB605 engines. The DB 605 had a vastly superior supercharger to the BMW 801 and thus didn’t suffer anything like the same performance penalty above 20,000ft. The Bf 109s were also much lighter. Once the Sturmgruppe had formed up ahead of the incoming bombers the Bf 109s would seek to engage the escorting fighters and keep them busy whilst the Stürmbocke would hit the bombers. A typical Stürmbock tactic would be to approach the bomber from astern and open fire at 1,000 yards with the MG131 and MG151 cannons in an attempt to suppress and hopefully kill the tail gunner. Once the range had closed to just a few hundred meters the Stürmbock would open fire with the 30mm MK108 cannons and these would rapidly turn a Viermot into metal confetti.

Jimmy Doolittle. In the inter-war years he undertook several of the pioneering US coast to coast flights, won several long distance air races and is credited with helping develop instrument flying. On 18th April 1942 he personally led America’s first bombing raid on mainland Japan. The eponymous Doolittle Raid involved launching B-25 medium bombers from the carrier USS Hornet which went on to bomb Tokyo. The B-25s were not able to land back on the carrier due to their large size, but instead ditched in the ocean and their crews rescued by the US Navy. Later on after being promoted to the commander of the US 8th Army Air Force in Europe Doolittle made the monumental decision to take the American escort fighters off the leash
See page for author [Public domain], via Wikimedia Commons

The Sturmgruppe worked quite well at first. Right up until early 1944 when Lieutenant General Jimmy Doolittle,  the new commander of the US 8th Army Air Force changed his tactics. Up until that point the bombers had close escort, that’s to say the escorting fighters would fly very close to the bombers and were not allowed to pursue the enemy fighters.

When he took command of the 8th AAF in March 1943 Doolittle commissioned the help of the British in improving the combat performance of his forces. The test pilots at the Royal Aircraft Establishment at Farnborough were asked to conduct a tactical evaluation of the current USAAF fighters with respect to their Luftwaffe counterparts. The RAE report concluded with the exception of the P-51, all the current American fighters were inferior to their Luftwaffe adversaries. A certain Royal Navy test pilot by the name of Eric Brown was involved in this and also helped develop a new escort doctrine for the Americans. The result was the Mustangs were taken off the leash. They no longer were required to fly close escort with the bombers and could range far above and ahead the bomber formations. This allowed the Mustangs to tear into the Sturmgruppe whilst they were still assembling. The Sturmgruppe were disrupted and scattered before they even had a chance to get anywhere near the bombers. You see my dear puffins, it wasn’t the Mustang which turned the war in the air over Germany, it was when the Americans worked out how to apply the Mustang correctly.

Doolittle’s decision to release the fighters from close escort of the bombers allowed the P-51 Mustang to reach its full potential. Had it not been for Doolittle this aircraft would not be the legend receiving the platitudes it does today
U.S. Air Force photo by Tech. Sgt. Ben Bloker [Public domain], via Wikimedia Commons

As an aside, one of the things the Germans worked out quite early on was the B-17 was very vulnerable to a frontal attack. The only direction its guns couldn’t cover was straight ahead. Some Luftwaffe pilots would attack from head on, open fire at the B-17s nose and kill or injure the crew located there including the pilots and bombardier. This was an extremely risky way to attack though. The closure rate would be around 500mph and the Luftwaffe pilot would have only seconds to line up, aim and fire before he had to get out of the way before he collided with the bomber. When the B-17G was introduced in 1944 it had another pair of heavy machine guns mounted in a chin turret on the nose specifically to defend against these kinds of attacks.

The chin turret introduced with the B-17G to defend against frontal attacks from Luftwaffe fighters
en:Mark.murphy [CC BY-SA 3.0], via Wikimedia Commons

Another interesting use of the Fw 190 can be found with the Wilde Sau, or wild boar units. This was a remarkably foolhardy use of the aircraft and takes a bit of explaining, so bear with me…

Early war efforts by Bomber Command involving daylight bombing were very disappointing and very costly. Thus Bomber Command moved to night bombing, where it became much harder for the Germans to find and shoot down the bombers. The early night bombing doctrine gave huge leeway to the individual bomber crews. They were simply told what the target was and it was left up to them to plot their course and timings. Each aircraft would fly alone in the darkness following their own plan. The Germans countered this with the Kammhuber Line. This created a defensive line of adjacent rectangular boxes stretching from eastern France, across Belgium and the Netherlands into Germany, across northern Germany all the way to the Baltic coast. Each box would have its own Freya early warning radar and a radar guided master searchlight as well as a number of manually operated searchlights, flak guns and two night fighters (one in the air and one backup). As the bombers approached the early warning radar would detect them. The radar guided master searchlight would locate a bomber and hand the target off to manually operated searchlights. The aircraft could them be targeted by the night fighters which operated in a “no-flak” band of altitude. If the target was outside the no-flak zone then flak guns would engage the target. This system was dubbed the Himmelbet, or four post bed system. Later on each sector would get two Wurzburg tracking radars. The Freya would be used to detect the bombers, One Wurzburg would be used to “lock on” and track a bomber, whilst the other Wurzburg would track the Luftwaffe night fighter. The ground controller could then give the night fighter very precise instructions to guide them close enough for their own airborne radar to take over. The RAF initially countered the Himmelbet system by developing the bomber stream. Now raids would all pass through one or two sectors and completely overwhelm them. As the Germans improved Himmelbet to counter this the RAF then began to use “Window” which would could be used to decoy the German defences. Window was the precursor of what in modern military aviation is referred to as chaff, a radar decoy. Window consisted of clouds of metal foil strips cut to specific lengths (the wavelength of the German radars). Specially equipped bombers would drop Windows in big clouds which would appear on the German radar sets and look like a bomber stream inbound to a target. The radar operators would report this and the controllers would direct their defences towards the Window decoy instead of the real bomber stream. Over time experienced German radar operators could spot the radar returns from the aircraft dropping Window at the edge of the decoy radar return and correctly identify it as a Window drop. Interestingly enough, the RAF had Window for a year before it was actually used and kept it a secret because they feared the Germans would copy it and use it on the British air defence network.

A general overview of the Kammhuber Line in 1944. This was the line of defence RAF Bomber Command would have to breach every night. The red boxes are the “Himmelbet” sectors and the yellow circles represent the heavy flak batteries around major population centres
Mullerkingdom [CC BY-SA 4.0], via Wikimedia Commons
A section of a map of the Kammhuber Line smuggled out of Belgium by the local resistance. Note the rectangular air defence sectors, dubbed “Himmelbet” by the Germans
See page for author [Public domain], via Wikimedia Commons

So the picture I’m trying to paint is by 1943 the Kammhuber line was under serious pressure. Far too many RAF bombers were getting through every night and the German defences were in danger of being overwhelmed. Particularly when the RAF began to sneak night fighter Mosquitos into the bomber streams to hunt the German night fighters on their own turf.

The Germans had the idea of using both the Fw 190 and the Bf 109 as a night fighter. No radar, no blind flying equipment. Just regular aircraft borrowed from daytime fighter units. They would take off and attempt to find bombers by themselves. This could either by by catching a bomber caught in a searchlight, or a bomber which is lit up by the fires of a burning city below it. Perhaps a bomber lit up by strong moonlight. Some of the more favourable methods used were catching bombers flying over a thin layer of cloud which was lit by searchlights or fires burning below.

Operationally Wilde Sau was a failure. Many pilots became disoriented and crashed in the darkness, others became lost over blackout Germany and had to bail out when they ran out of fuel before finding an airfield to land at. Others crashed on landing. The daytime fighter units these aircraft were borrowed from also protested very loudly about the attrition rates and their aircraft being lost. There was also the issue of if the aircraft are being flown at both day and night, when do you do the maintenance?

The autumn and winter of 1943-44 also had some especially inclement weather and the rate of non-combat losses for Wilde Sau aircraft spiked significantly. Eventually Wilde Sau was put to rest in the spring of 1944. The number of RAF night bombers shot down never really justifying the number of fighters lost operating at night without the proper equipment. The Germans did continue operating single engine night fighters, but by this stage they had proper blind flying equipment and radars installed.

The next, and final part of this article we’ll go over the dedicated late war fighter bomber variants of the Fw 190, and the efforts to improve the high altitude performance of the aircraft which resulted in possibly the best fighter of the war. We’ll also take a look at some mistletoe and what many regard as the best fighter that never was.

Luftwaffe ground crew loading a W.Gr.21 rocket mortar onto an Fw 190A-8/R6
Bundesarchiv, Bild 101I-674-7772-13A / Grosse / CC-BY-SA 3.0 [CC BY-SA 3.0 de], via Wikimedia Commons


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