Lot 144
A pair of cross section plans of the Mohne Dam to illustrate the intended path of the Upkeep mine stencilled "CROSS SECTION OF MOHNE DAM" and "CROSS SECTION OF UPPER PART OF MOHNE DAM". The main dam plan displaying a blue mine against the dam freeboard and another example of the red mine further down at 30 metre depth (the detonation point). The water has been added with a cumbersome blue crayon/pencil, the torpedo nets indicated by a yellow crayon buoy. At the top of the plan is a pencilled skimming bounce motion and there are pencilled formulae to the centre of the plan. A label bottom right stating Dr. Barnes Wallis used the plan to brief 617 Squadron on the night of the raid. Plan framed 83cm h x 109cm w (unframed x 73cm h x 100.5cm) The upper dam plan details a close up view of the mine striking the freeboard of the dam, the water side in coloured blue crayon, and then another depiction of a red mine at 30 metres depth - a light red pencil indicates 'detonation depth'. Plan framed 82cm h x 94cm w, (73cm h x 84.5cm w unframed) Both plans label to verso "loaned to RAF Museum by Sir Barnes Wallis" together with RAF stock label circa 1971.  £10000-15000