Sunday, June 1, 2014

Focke-Wulf Ta152A

One of the significant planned lines of manufacture for the Ta 152 series was as a fighter and heavy fighter for low to medium-level oper¬ations. In some respects these roles were also allied to the Ta 152C fighter-bomber development programme, and they would have led to a completely different line of Ta 152 manufacture separate to the well-known high-altitude Ta 152H series and the fighter-bomber Ta 152C versions. Two distinct models of the fighter/heavy fighter Ta 152 for low to medium-level operations were eventually envisaged, the Ta 152A fighter and the Ta 152B heavy fighter (particularly in its Ta 152B-5 version). The Ta 152A was in fact one of the initial production models that was planned from the Ta 152 line, and would have been a standard fighter for low-level to medium-level operations but with enhanced features over and above the Fw 190D-9 series then also being developed. Otherwise the Ta 152A was to have been a compara¬tively straightforward adaptation of the Fw 190A airframe, but with important changes and upgrades which were to include the installation of a Junkers Jumo in-line engine, and the adoption of the 30mm MK 108 cannon centrally mounted to fire through the propeller hub — the latter marking out the Ta 152A from the Fw 190D-9, which did not have a cen¬trally-mounted cannon (instead it had two machine guns mounted in the forward fuselage above its Jumo 213A engine). The introduction of hydraulic actuation for the undercarriage and flaps instead of the pro-duction Fw 190's electric system, and the adoption of larger tyres. were two further major differences compared to the Fw 190A series. In addi¬tion the type was intended to have the wide-chord vertical tailplane that had been devised for the Hohenjager programme. Initially Focke¬Wulf's plan was to make a fairly straightforward adaptation of the stan¬dard Fw 190A, to allow ease of manufacture. However, from the start it was intended to re-engine the new Ta 152 line with powerplants differ¬ent to the BMW 801 radial of the Fw 190A. For the Ta 152A, the engine was planned to be the Jumo 213A, the mark of Jumo that was also used to power the successful Fw 190D-9 fighter derivative of the Fw 190A fighter series.

To accommodate the new engine layout and the increased forward arma-ment, it was necessary to lengthen the forward fuselage by 772 mm (30.39 in), with the resulting extension being attached directly onto the existing fixtures for the previous radial engine in order to save time and minimise new tooling. However, this major alteration to the fuselage dimensions also resulted in the wing assembly needing to be moved for¬ward 420 mm (16.54 in) compared to the Fw 190A to regain the centre of gravity. This resulted in the rear spar junction with the fuselage being altered, with a fuselage bulkhead having to be repositioned due to this which caused a re-design to be necessary for the forward fuselage fuel tank's compartment. The forward fuel tank ahead of the cockpit was retained and continued to hold some 233 litres (51.3 gal). but the fuel tank behind the cockpit was increased in size to hold 362 litres/79.6 gal (some 70 litres/15.4 gal more than that in the Fw 190A). Provision was also made for the installation of an additional 115-litre (25.3-gal) fuel tank in the rear fuselage if required, and a separate tank of 85-litre/ 18.7-gal capacity for GM 1 nitrous-oxide to provide additional engine boost at high level. All these changes led to the necessity of the addition to the rear fuselage of an extra section, of 500 mm (19.69 in) length, to compensate for the additional weight and length at the forward end of the fuselage caused by the new engine, its equipment, the new centrally-mounted cannon, and the lengthened forward fuselage. This new cylindrical section served to accommodate the compressed air bottles necessary for the operation of the new forward cannon, and the oxygen bottles for the pilot. It made the fuselage length of the Ta 152A 10,784 mm (35 ft 4.6 in). The Jumo 213A-powered Fw 190D-9 also need¬ed a similar rear fuselage extension, and so with these changes the design layout of the original standard radial-engined Fw 190A series was already undergoing a radical makeover. The problem with any kind of aerodynamic tinkering of this kind is that it is the original design that is the one that fits all the designers' original calculations. When pieces are added on, these nicely-balanced original equations are all altered and thrown out of sequence, and so the whole Ta 152 series was really based on a reconstitution of the original set of parameters that worked so well with the Fw 190A; this can be a risky strategy, and in the case of the Ta 152 the initial aerodynamic cleanness and good handling of the Fw 190A design was compromised in order to uprate and upgrade the

original design. to suit the developing needs of the R.LM and Focke-Wulf's desire to create what was in effect a new warplane out of the exist¬ing Fw 190 design. An immediate consequence was the need to beef up the fuselage structure to try to accommodate all these changes and extra weight, with steel extrusions replacing the existing duralumin ones. Additionally, this major tinkering with the fuselage took place alongside a significant change to the wing configuration. The existing wing span of the Fw 190A series of 10,500 m (34 ft 5.4 in) was increased by the installation of a 500 mm (19.69 in) extra section in the centre of the wing assembly (the Fw 190's wing was manufactured as a one-piece structure from wing tip to wing tip, and this concept was initially retained for the Ta 152A, but with the addition of the extra section in the centre of the assembly). The reason for this addition was the necessity to reposition the main undercarriage a little further out in the wing on each side, ostensively so as the allow propeller clearance for the larger tyres, although it was obviously moved outboard anyway due to the addition of the extra section in the centre of the wing assembly. All this work increased the wing span of the planned Ta 152A to 11,000 mm (36 ft 1.1 in). Although the main undercarriage legs were retained virtually the same as on the Fw 190A, the mechanism for their retraction was altered so as to accommodate the different linkages for the new hydraulic retraction, and to do away with the prominent electric drive assembly that was a feature of the Fw 190A's main undercarriage bays. Due to the alteration to the wing's centre section, it was necessary to re¬design the wing-to-fuselage joint, and also to beef up the skinning of the inner wing sections.
Early in the development of the Ta 152A it became apparent that it would be necessary to install the Jumo 213C-series engine rather that the Jumo 213A, as the latter had no provision for the installation of a weapon firing through the propeller spinner (the so-called 'engine-mounted' installation), but the Jumo 213C (as well as the Jumo 213E) did have this capability. The way in which the Jumo 213 engine would be installed in the Ta 152A was imaginative, in similar fashion to the instal-lation of the Jumo 213A in the Fw 190D-9. in that the engine's radiator would be placed at the front of the engine in the extreme nose in an annular fitting. This would give the Ta 152A, like the Jumo 213A-powered Fw 190D-9, the appearance of being radial engined with a prominent round frontage, when in reality all these versions were powered by in-line engines. Work began as Soon™™ as possible after the May 1943 meet¬ing between Focke-Wulf and Technisches Amt personnel on the cre¬ation of prototype/development aircraft for the new Ta 152A. In the event three prototypes eventually existed which were intended to develop the Ta 152A concept. All three were converted from early Fw 190A-0 pre-production development aircraft. In their new guise they were designated Fw 190V19, Fw 190V20, and Fw 190V21. Conversion work on these aircraft was carried out at Focke-Wulf's Adelheide (Del¬menhorst) experimental facility near to and west of the main Focke-Wulf plant at Bremen. These aircraft had been earmarked for conversion as a part of the Fw 190C Hohenjager 2 development programme but in the event were used instead for the Ta 152A project. It had been intended that two new-build aircraft, which would have been the very first aircraft to carry the Ta 152 nameplate, the Ta 152V1 (W.Nr. 250001) and Ta 152V2 (W.Nr. 250002) (`V' standing for Versuchs or experimental test or development aircraft), would have been constructed for the Ta 152A-1 initial production development. They were not built, however, and prototype testing for the whole Ta 152 series began with the three converted Fw 190A-0 examples.

Of these initial Ta 152 development aircraft, the first to fly was the Fw 190V19, W.Nr. 0041. This historic but often overlooked aircraft made the very first flight of a Ta 152-related machine, on 7 July 1943. At that time the official Ta 152 nameplate had not been officially approved, although it was delegated to Focke-Wulf in the ensuing weeks. The Fw 190V19 was followed into the Ta 152A test programme on 23 November 1943 by the Fw 190V20, W.Nr. 0042, TI+IG, when Focke-Wulf's head of flight testing and development flying, Hans San¬der, took this equally important aircraft up for its first flight after con¬version into the V20 configuration. The third Ta 152A prototype, the Fw 190V21, W.Nr. 0043, TI+IH, first flew on 13 March 1944 with Focke¬Wulf experimental test pilot Bernhard Marschel at the controls. The flight testing of these aircraft proved to be generally successful. San¬der and Marschel subsequently made many of the test flights during the whole Ta 152 development effort in the following months. Interest¬ingly, an unexpected problem that surfaced during the company tri¬als was that of resonance. This was a phenomenon that was less understood in 1943 as it is today, and the V19 ran into this problem almost right from the start of its flight testing. The difficulty centred around resonance in the airframe, caused by the Jumo 213A engine running rough. In fact the V19 eventually had three different Jumo 213A engines fitted at different times, but the problem never really went away. It was later discovered that installation of the Jumo 213C engine, which had a revised ignition firing sequence. partly solved

As a part of the development effort for the Ta 152A-series, the development Fw 190V20,W.Nr. 0042. TI+IG, was fitted with flame dampers to shield the glare from the exhausts of the aircraft's Jumo 213 engine in low light conditions. This gave a very smooth appearance to the engine cowling as seen here, with the single special exhaust outlet relocated to just above the wing-root on each side where it would not blind the pilot. Nevertheless the whole programme led to a very negative effect on performance and the project was officially dropped in April 1944.

the problem — this engine type was fitted to the V20 and V21 aircraft, but not the V19. The type of propeller fitted also caused concern as it was a part of the resonance phenomenon. It was intended that a three-bladed VS 9 propeller unit would be fitted to the test aircraft, but this type of wide-chord propeller was made by several compa-nies and there were differences in the quality and balancing of the propellers from the different companies. The best seem to have been made by the long-established Schwarz company.
Much time and development effort was lost during the test work on the three Ta 152A prototypes due to the attempted installation of a flame-damping system to the exhaust. It appears that the RLM was interested in the Ta 152A being used as a 'Wilde Sau' ('Wild Sow/Boar') austere night fighter, but the resulting development effort to flame-damp the Jumo engines' exhaust proved to be a complete waste of time. The V20 was the first to be fitted with a trial installation, which comprised the channelling of the engine's exhaust gases into a straight collector pipe which exhausted with a single exit low down on the fuselage side above the wing root on each side. The V20 featured a straight pipe while the V21 had a slightly modified less straight pipe. A significant result of these experimental installations was a considerable reduction in per-formance. The V20 achieved 657 km/h (408 mph) at 7,600 m (24,930 ft). but this was some 25 km/h (15.5 mph) slower than anticipated. The flame damper system was eventually replaced by a normal exhaust lay-out, and was officially abandoned in April 1944.

Development work was also undertaken to determine the optimum shape for the supercharger air intake on the starboard side of the engine cowling. The Jumo 213A and C were fitted with a single-stage supercharger with two-speed gearing, and this needed quite a large, streamlined intake to be perfected. It must be stressed that this engine was not turbo-supercharged (i.e., it did not have supercharging from the recycling of hot exhaust gases, but instead used air). Unfortunately the V19 was involved in a crash in February 1944 which left just the two other aircraft to continue the Ta 152A development effort.

A variety of armament options were considered for the Ta 152A. From the start it was intended that this would be a heavily-armed aircraft. with the armament centred around an 'engine-mounted' installation fir¬ing through the propeller spinner. This was to be either the 30mm MK 108 cannon with 85 or 90 rounds (Focke-Wulf documentation sug¬gests that this would have been the configuration for the intended Ta 152A-1 production version), or the 30mm MK 103 cannon with 75 or 80 rounds (for the planned Ta 152A-2, although this and the A-1 pro¬duction configuration were never officially confirmed). Two 20mm MG 151/20 cannons were to be fitted in the upper fuselage over the engine with 150 rounds each, plus one of these weapons in each wing root with 175 rounds each. As with all of these wing root and upper fuselage-mounted weapons in Fw 190 and Ta 152 aircraft, they were synchronised to fire through the arc of the propeller. There was also the option of two more weapons in the outer wing outboard of the under¬carriage installation in various Rtistsatz field conversion combinations. These would have been either two 20mm MG 151/20 cannons (one in each wing) with 140 rounds each, or two 30mm MK 108 cannons (one in each wing) with 55 rounds each. Unusually, an external fitting outboard of the undercarriage was also considered, with an MK 103 cannon under each wing with 40 rounds in a streamlined fairing. An ETC 503

weapons rack would also have been fitted beneath the fuselage centre¬line, able to carry bombs of up to 500 kg (1,100 lb), or a 300-litre (66-gal) external fuel tank on a modified mounting.
All seemed to be set fair for the Ta 152A to enter series production with the successful testing of the three development prototype aircraft. Indeed the third aircraft, the V21, W.Nr. 0043, was seconded to the Erpro¬bungsstelle (E-Stelle) military flight test and research establishment at Rechlin to the north of Berlin in May 1944. Everything. however, had gone wrong for the Ta 152A by that time. In October 1943 Focke-Wulf had applied to the RLM for development priority for the Ta 152A. This propos¬al was rejected, and worse was to follow, for in December Focke-Wulf again made an unsuccessful proposal for go-ahead. In January 1944 Focke¬Wulf representatives met with the RLM to attempt to move ahead this sec¬ond proposal, which included the Ta 152A, the Fw 190D (the re-engined Fw 190A fighter development with a Jumo 213A engine), and a further Ta 152 version, the Ta 152H. which was at that time under development for high-altitude fighter requirements. This request too initially did not receive official approval, and for a time the whole Ta 152 project appeared to be in jeopardy. The RLM's reluctance to proceed at that time appears to have centred on two specific points. Firstly, the plan of introducing a derivative of the established and successful Fw 190 line - which by that time includ-ed the Fw 190A fighter and fighter and fighter-bomber series, in addition to the Fw 190F and Fw 190G series which were dedicated to air-to-ground missions - was considered as a potential danger to the continuing produc-tion of these types, with too much diversification of effort if the Ta 152A went ahead. Secondly, a rival to the Ta 152A also existed. This was the Messerschmitt Me 209, an uprated development of the established and famous Bf 109 series of fighters and fighter-bombers. The first develop-ment aircraft of the planned Me 209A fighter and fighter-bomber flew on 3 November 1943 (this aircraft was actually the Me 209V5, SP+LJ), and the RLM appears to have become distracted by this new design, to the extent of holding up the production go-ahead for the Ta 152A. When problems developed with the Me 209 series and the type never received a green light for production, the general war situation had changed and the Ta 152A never received production go-ahead. This must have been a huge disappointment to Focke-Wulf, as the Ta 152A promised a great deal in uprated performance and fire-power compared to the Fw 190 models then in production, particularly but not exclusively at higher altitudes but specifically above 5,000 m (16,400 ft). Indeed, the Luftwaffe appears also to have wanted the Ta 152A to go-ahead, and the type remained on the mil-itary procurement list until the early part of June 1944.

In the event, the two remaining development aircraft of the Ta 152A pro-gramme, the Fw 190V20 and the Fw 190V21, were re-assigned to other projects. They were intended to be re-engined with the Daimler Benz DB 603E or L-series engine as test-beds for the then on-going Ta 152C project. However, on 5 August 1944 there was a devastating US air raid by the Eighth Army Air Force on the Focke-Wulf experimental and produc¬tion plant at Hannover-Langenhagen. Several development aircraft from the Ta 152 trials programme, as well as other Focke-Wulf aircraft, were badly damaged or destroyed. Amongst them was the V20. It was a sad finale to what could have been, but for the RLM's hesitation and bad deci¬sion-making, a very useful production variant in the form of the Ta 152A.

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