Heinkel He 280
ABOVE: The second He 280 takes off without the cowlings of its engine nacelles. The HeS 8A engine was notorious for minor fuel leaks – which could result in a dangerous build-up of flammable liquid within the cowlings over time. via author
ABOVE: The Luftwaffe’s director general of equipment, Ernst Udet, tries the He 280 V2’s cockpit for size. Udet was a supporter of turbojet technology and apparently the He 280 in particular. via author eight of them would be needed to get the He 280 off the ground – four under each wing. If the He 280 was still towed aloft however, just two under each wing would be required and flight testing, at least, could become more regular. In May, the RLM requested that one of the He 280 prototypes be reconfigured to fly using BMW’s P.3302. When informed of this, BMW apparently expressed concern that its engine was simply not yet powerful enough for flight testing. It seemed that all hopes were being pinned on the He 280 at this stage, as on May 29, 1942, the RLM scrapped plans for a lengthy series of prototypes from Messerschmitt and told
the firm that only five Me 262 experimental airframes would be needed. At this stage, a series of 24 He 280 prototypes was still on order. The first delivery of six As 014 pulse jets arrived at Heinkel from the Argus factory in June 1942. Meanwhile, von Ohain was making more progress with the HeS 8A and a new development, the HeS 8B, was under way. Flight testing of the He 280 V3 with HeS 8A engines commenced on July 5, 1942. The engine crisis was far from being resolved, however. As the year wore on, it was decided that the pulse jets should be fitted to
He 280 V1 for testing at Rechlin. The V2 and V4 airframes would then be reconfigured to fly using the Jumo 004 when working examples were available – the V4 also receiving larger fuel tanks and upgraded weapons. The new weapons load was to consist of either the three MG 151s plus two MG 131s or the same four guns plus a single MK 108 30mm cannon. In contrast, the Me 262 V3 prototype had regularly begun flight testing reliably with a pair of Jumo 004 turbojets – exactly the sort of performance breakthrough everyone had been waiting for. In September, Heinkel looked at equipping the He 280 with two HeS 8As and two As 014s. This would, it was hoped, result in a top speed of 534mph – compared to the top speed of 500mph that was anticipated with just a pair of HeS 8Bs. The same number crunching exercise concluded that a He 280 fitted with eight As 014s would have a top speed of just 440mph. Even this would, however, still make it faster than any piston-engine aircraft then in service. The following month, it became clear that fitting Jumo 004s to the He 280 V2 would not be straightforward since there would simply not be enough ground clearance. A substantial amount of strengthening and lengthening work would also have to be done to the undercarriage of He 280 V4 before it could accept the engines. It was also taking longer than expected to satisfactorily fit the As 014 pulse jets to He 280 V1. The work was due to be completed by October 25, 1942, but this deadline passed and the V1 remained incomplete. On November 18, 1942, the RLM’s tolerance of the protracted delays involved with the He 280 programme was nearing its end. Just as it had previously done with the Me 262, it reduced the number of prototypes on order – from 24 down to six, plus one unpowered aircraft for high speed testing. It now seemed as though the Me 262 was the front runner. It had proven that it could fly with its Jumo 004 engines. Field Marshal Erhard Milch, the man in charge of German aircraft production, made jet development an even greater priority on December 10, 1942, when he effectively overrode Hitler’s earlier directive with Projekt Vulkan. This gave five new aircraft types top priority for the procurement of materials and equipment – the Me 163, Me 328, Me 262, Ar 234 and He 280. BELOW: The Heinkel He 280 V1 DL+AS in fight as a glider with dummy engines fitted. via author
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Luftwaffe: Secret Jets of the Third Reich