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Thread: Planned descents of 12-13,000/minute by four engine a/c?

  1. #21
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    I agree with t'other Richard. Height changes were a feature of raids late in the war - there's an ORS study report that recommended the practice, which I can't find. However, Harris's Despatch on War Operations says in Annec C, Tactics:

    68. A further tactic, which was employed with success throughout this phase [Sep 44 - May 45] and which was useful both in evading fighters and in shaking them off when they had once made contact, was that of making considerable changes in height at various stages of the route. Since fighters were normally expected to make contact at the target it became the practice to lose height rapidly on leaving the target area, a manoeuvre which was most successful on a number of occasions. The planning of height changes en route was left to the discretion of groups, except when one bomber force was comprised of aircraft from several groups or when groups, on their way to different targets, followed a common route for any distance. In these instances co-ordinating of height planning took place at Command Headquarters. (p 127)
    However, 12/13,000' per minute seems quite challenging. Two snippets seem to suggest this -
    1) is a survey of Groups on their preference for the Bomber Command or 5 Group corkscrew - the 3 Group response suggests that 240-250 IAS is the maximum acceptable speed at the bottom of the dive - and 'it is felt better to teach pilots the best way to fly a Lancaster at 240-250 m.p.h. I.A.S. and have them able to carry out an effective corkscrew, than to keep the speed down to 210-220 m.p.h., which does not call for as much skill...'
    2) is a letter entitled 'Rates of Dive of Lancaster and Halifax Aircraft' in AIR14/2686 'ORS Reports Nov 43 - Feb 44' (although letter is actually dated April 44). This says '...there is little information relating to the greates rates of dive achieved on operations by a/c of this Command...[Automatic Observer] records show … the maximum rate of dive recorded was 4,000' feet/min, but this was only maintained over a period of 1/2 minute while the a/c was at a mean height of 17,500'. Rates of about 3,000ft/min over very short periods seem fairly common.'

    I'll check the Lancaster Manual when I get home tonight.

    Richard
    Last edited by Richard; 26th February 2020 at 10:27.

  2. #22
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    Why not put this problem to the BoBMF at Coningsby? I'm not suggesting that they go out an try it on the Lanc, but they will be aware of the Lanc airframe structural limitations? The climb/descent dial in the Lanc is an indicator - it's not connected to the autopilot, therefore it's not a command instrument.
    Better, perhaps, to have ringing/painful eustachian tubes/ears for a few minutes, and to nearly over-stress the airframe, than to be shot out of the sky?
    HTH
    Peter Davies
    Meteorology is a science; good meteorology is an art!
    We might not know - but we might know who does!

  3. #23
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    Quote Originally Posted by ianh View Post
    Has anyone checked the location of that co-ordinate given in the raid instructions to see where that is and how far from the target? It might (rpt 'might') indicate whether the descent was rapid or gradual.
    Just a thought.
    Ian
    I have plotted all the routes of my father's operations on google maps. I start by putting in the coordinates for each turning point in Google Maps and then use "Trig" to calculate the "Great Circle" distances and "Initial Bearings" (headings) between turning points. Note that I don't use the same names as Bomber Command for the points as quite simply, I don't as yet have these. BC used Letters. These are not archived as near as I can tell. However the coordinates for the turning points are well documented and consistent across the different sources, so I am quite confident. Now these flight plans just refer to "Target" for such, and do not provide the coordinates for them. I suspect the crews were shown target photos at briefing and the exact location of the aiming point was described verbally. For area raids, I'm fine with just using the centre of the city for now. For small targets such as oil facilities (for example Scholven Buer), I have sourced the exact location of these and these are displayed. I use "string arithmetic" to create comments for each turning point and then the coordinates in MS Excel are exported as KML files and imported into Google maps. Note that these routes visually match quite closely the charts archived in the Bomber Command Night Raid reports.

    Oberhausen November 1-2, 1944
    https://drive.google.com/open?id=10h...My&usp=sharing
    Note the purple "bubbles" denote approximate location of Nachtjagd claims.

    The following is my text for the flight plan:

    "From Base, the station aircraft set course and climbed at 160 IAS to 10-12,000 to TP2, heading nearly south, bearing 173o T for 70 miles. The Force was to hold height at 170 IAS and to continue south to Reading, heading 175o T for 142 miles, then SE to Beachy Head, heading 132o T for 73 miles and continuing on to cross the French coast near Fort-Mahon-Plage at TP5, heading 117o T for 62 miles. The Force then changed course nearly due east and at 04oE to begin the climb to bombing heights (19-20,000) and continue past Charleroi to TP6, heading 87o T for 140 miles. The Force then turned NE, crossing the battle line NW of Aachen and continuing towards Target Oberhausen, heading 50o T for 123 miles."

    Upon leaving the target area, the force altered course NW to TP8, heading 285o T for 24 miles all the while descending rapidly 12,000 per minute at 240 IAS and a height of 10-11,000 and then changed course to SW TP9, heading 236o T for 70 miles.
    "

    Dusseldorf November 2-3, 1944
    https://drive.google.com/open?id=1yo...lE&usp=sharing

    From Base, crews were to set course and climb at 160 IAS to 13,000 to TP2, initial heading 173o true for 70 miles and then to alter course to Reading 175o for 142 miles. The force was to then turn to Beachy Head, heading 132o for 73 miles and then crossing the coast of France at TP5 near Fort-Mahon-Plage, heading 117o, and distance 62 miles. At some point along the route, (position uncertain) the force was to climb at 155 IAS to 18/19,000' and then to level out and cruise at 160 IAS to 05o00E on track. The force then headed ENE (heading 64o) on a long leg of 207 miles to TP6, just NE of Helmond before turning SE, heading 116o for 46 miles to Target Dusseldorf. On the leg to the target, crews were disperse to bombing heights at 155 IAS and cruise at 18/18,500 (165 IAS); 19/20,000 (160 IAS); 20,500/21,000 (155 IAS) to just short of target.

    After bombing, the force increased speed 10 mph and maintained bombing heights to easterly for 4 miles to TP8 on the outskirts of Dusseldorf, initial bearing 130o T. At this point, crews turned SE (216o), distance 64 miles, while descending rapidly 12-13,000/min at 240 IAS to reach towards TP9 at 7-8,000. The force then leveled out and cruised at 190 IAS almost W (267o) to TP10, west of Valenciennes, distance 118 miles before turning NNW to Orfordness, (328o), distance 143 miles. Crews then headed to their bases (311o) via TP12 (153 miles) at own speeds and at heights not less than 6,000 and then 70 miles north (354o) to Middleton St George.


    Jim
    Last edited by JDCAVE; 26th February 2020 at 17:08.

  4. #24
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    After review of this discussion and the contribution of everyone here, I'm pretty certain that the "Rates of Descent" described in the flight plans for these operations are likely in error, probably out by a decimal place, i.e. 1,000-1,300'/minute rather than 10,000-13,000' minute. Although these are theoretically possible at 250 MPH and an angle of descent of 30-45o. However as the described descent is well outside of the range of the "climb-descent" instrument on the a/c, it's seems unlikely to me that such a steep descent would have been realistic and outside the capability of some pilots.

    Still: I think a review of the associated "Form B's" for these operations would go a long way towards a definitive conclusion.

    Edit: I am aware of an "aircraft Test" for 419 squadron in March, 1945, where the pilot put the a/c into a dive for a corkscrew maneuver, and severely damaged the main spare and fuel tanks. A reliable "eye" witness (grounds crewman who was aboard for the test and who reported this in a letter to my father in 1984) said that both he and the rear gunner blacked out during the procedure.

    Jim
    Last edited by JDCAVE; 26th February 2020 at 18:12. Reason: Additional info

  5. #25
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    Interesting plots, Jim.
    For 2/3 Nov your turning point 9 is a fair match (about 4 miles further S) with that I found by another tool, on coordinates alone.
    Excuse me pointing out that the course (216) is SW, not SE.

    How two doc copies got it wrong is a puzzle, however it does seem likely that the intent was 1200/1300 ft/min descent, rather than 12000/13000 ft/min (mistyping an extra 0).
    I think Jim is right to pursue additional original docs for confirmation.

    On instruments and operational flying, there's a fair amount of horse's mouth in the literature.
    It's one thing to have to exceed either "the book" limits or have the instruments on the stops, in the extremity of interception.
    It certainly happened, with boost limits, rev limits, temp limits and "speed not to be exceeded" limits - any or several of which might be ignored and could be got away with from time to time in the course of sustained or violent evasive action. Plenty of first hand anecdotes of the time, and across theatres of operations.

    It would be another thing altogether to order, beforehand, that an entire formation, with pilots of varying skill levels, should undertake a manoeuvre beyond the capacity of the flying instruments to display in aiding pilots carrying out the manoeuvre.

    Footnote
    For future ref (though he and others may already know), the Bomber Command Night Raid Reports referred to by Jim can be seen online at http://www.lancasterbombers.net/night-raid-reports/

    Don Clark
    www.211squadron.org
    Last edited by Don Clark; 26th February 2020 at 21:46. Reason: Footnote added
    Toujours propos

  6. #26
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    Quote Originally Posted by Don Clark View Post
    ...Excuse me pointing out that the course (216) is SW, not SE...
    Don Clark
    www.211squadron.org
    There is no excuse! LOL!

    Thanks for the correction!

    Jim

  7. #27
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    Just a couple of thoughts about this subject.
    Whilst I can definitely see the tactical value of a rapid change of altitude,I do also wonder if there might have been other secondary/additional reasons ?

    (1) Wind Forecast
    Our prevailing wind is Westerly (ie from the west),windspeed usually increases with altitude so a decrease in altitude would potentially give a large increase on Groundspeed,thus shortening sortie length and fuel consumption.

    (2) By Nov 1944 the allied front lines were knocking on Germany's front door - so a dive away towards the Belgian border would put the Aircraft over reasonably friendly territory at a lower (and therefore potentially warmer) altitude with no requirement for oxygen use (crew comfort).

    (3) Would also potentially give much greater 'altitude separation' with any other 'incoming' raids.

    rgds baz

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