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Lancaster II / Beaufighter IIF

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    Lancaster II / Beaufighter IIF

    Isn't it curious that the Bristol Hercules powered version of the Lancaster, the Mark II, was the lower performing version of the Lancaster...

    ...and yet the Rolls-Royce Merlin powered version of the Beaufighter, the Mark IIF, was the lower performing version of the Beaufighter.

    These versions were, I think, produced concurrently for basically the same reason: concerns about the availability of the preferred engine due to other aircraft priorities or enemy action.

    A similar situation occurred with the Halifax and the Lancaster; the Halifax was better with Hercules engines, the Lancaster was better with Merlin engines!

    In what way was the Hercules-powered Lancaster inferior? Speed, ceiling, fuel burn, reliabilty, maintainability?



      Didn't it have a lower ceiling? I might be imagining that.
      Armchair enthusiast, but also a fan of sofas and recliners.


        The Beafighter had a lower ceiling, you cant stand up straight in it.



          The Hercules engine provided a lower ceiling than the Merlin in the Lancaster, and perhaps a shorter range, but the other aircraft need to be looked at individually.

          Comments about the Beaufighter Mk.II seem to centre on handling difficulties, so it is probably the extra side area forward of the nacelles proving unstabilising. Any range difference would be comparatively unimportant.

          The Merlin installation on the Halifax suffered from being designed a few years ahead of that of the Lancaster, before the research at Farnborough was published on the ideal position of engines. Thus it was higher in relation to the wings introducing more drag, plus it suffered from an earlier generation of engine cooling due to the Gallay radiators. The RR heritage book on RR and the Halifax blames the problems on a refusal to fit the RR power egg, but as this wasn't available when the original design was laid down it seems inaccurate. (Whether the power egg was quite as valuable overall as RR claimed is of course another matter.) After all, the Manchester installation was designed at the same time as the Halifax and it lacks a power egg installation and also had the Gallay radiators on the Vultures. The Halifax Mk.II series 2 and the Mk.IV were designed with lower-mounted Merlins and the Morris block radiators, but did not go into production. Perhaps they would have been better than the Hercules Halifax, but the latter was good enough with less disruption of production.


            As stated above the issues of why one engine was better than the other was entirely different for the two aircraft. The Halifax is the more interesting as when you investigate it the Halifax issue was drag. The airframe was cleaned up to reduce the drag, but the major issue was with the Merlin Engine and the way it was mounted high on the wing with the exhaust stubs in line with the centre of the wing, requiring a large manifold to route the hot exhaust over the wing. This manifold was both heavy and draggy and glowed in the dark and acted like a magnet to night fighters. A fully laden Merlin 20 or 22 powerewd Halifax II had to use full throttle to maintain airspeed just above the stall, and evasive action such as the corkscrew would likely result in a stall. Could it be that many of the over rudder issues were the result of pilots inadvertently stalling the aircraft?

            Another fact was the high load factor on the engines caused service issues and accentuated problems that could otherwise have been managed, the radiators being one such issue. Handley Page and Rolls Royce never saw eye to eye over the engine mounting position, and the fitting of the Hercules, combined with all the other improvement resulted in a much better aircraft.

            But a Halifax was flown with Merlin 22 or 24’s in what RR considered the correct location and a marked improvement was achieved. Also Merlin 60 series where flown and showed better performance than the Lancaster (as they would) But Handley Page was not interested by then and was content to just fit the Hercules
            Last edited by TempestNut; 22nd April 2018, 15:41.




                are you for real mate
                Cheer's all far and WIDE!! , Tally Ho from Phil in Oz!

                WHAT GOE'S UP MUST COME DOWN


                  The manifold story is a bit irrelevant - they weren't all that heavy. It was the high position of the engine that was aerodynamically disadvantageous. This was something that came out of prewar RAE studies after the HP56/57/Manchester but before the Lancaster. It was better to have the engines below and forward of the wing - the same argument applies to externally-slung weaponry on later types. Whereas RR were more interested in the "power egg" approach, which not only saved maintenance time but meant more work/money to RR that would otherwise belong to the manufacturer. However it wasn't HP that wasn't interested in better Merlin installations for the Halifax but the Ministry, once the potential of the Hercules version was realised. Not the only example where improvements to the Halifax were denied - bulging the bombbay for the 4000lb and 8000lb bombs were allowed for the Lancaster but not allowed for the Halifax, not even the Mk.III.

                  Let's be fair: the Halifax could fly perfectly happily fully loaded well above the stall and did - except when close to its ceiling. This last is the key point.


                    Comparison between Halifax and Lancaster at 60,000lb all up weight in 1942

                    Altitude IAS rpm Boost
                    Lancaster 18,000 feet 175 2300 +3
                    Halifax 18,000 feet 168 2950 +8
                    Halifax 18,000 feet 128 2660 +5 1/4
                    Halifax 16,000 feet 130 2650 +4