Dam Buster query

Op Guzzle was the disposal of the Upkeeps…

Upkeep

Some Lancasters were eventually converted back and some retained, being used for disposal of the Upkeep mines after the war (Operational Grapple).

I thought Operation Grapple was Britains A bomb tests?

Was the mid upper not installed in the first place or removed later on? And would the hole left by the mid upper have been patched up or would a smooth skin have covered the entire upper surface of the fuselage?

Original authorisation was for 30 Lancasters but only 23 were converted, all Lancaster Mk IIIs. Conversion was carried out on the production line under the supervision of Roy Chadwick apart from three prototypes modified by Vickers engineers at the RAE Farnborough. Late modifications were made at RAF Manston (trials station) and RAF Scampton. The mid-upper turret was removed to save weight on Chadwick’s recommendation. The first converted Lancasters were towards the end of the production run that included fittings for a ventral gun. At least four of the 464s included these fittings but did not carry a ventral gun on the raid. Following the raid the 464s were initially retained while the possibilities of using the upkeep mine again were considered. Some Lancasters were eventually converted back and some retained, being used for disposal of the Upkeep mines after the war (Operational Grapple).

They all went directly from the factory to 617 ( or, in the case of the protoypes, to Boscombe, Manston, etc ). I’ve never seen it confirmed anywhere as to whether the airframes were ‘converted back’ or ( more likely, as Eddie suggests ) altered on the production line.

One of the best sources for the airframe details is Ward/Lee/Wachtel’s ‘Dambuster’ history.

I think ‘converted on the production line’ is the simplest way of putting it. I don’t think any of them saw any service (or probably even flew) before they were converted.

I think they were all stock Lancs which were converted.

I think they were all Lancaster III’s fitted with Merlin 28’s which were modified to become “Type 464 Provisioning” Lancasters (according to John Sweetmans’s “The Dambusters Raid”).