Hi
tinpis,
There's no way DA were considering the Comets as freighters.
The airline industry even back then was flush with dedicated cargo hulls.
The Comets were bought cheap for the specific purpose of moving people using various holiday charter agreements.
Even an amateur looking at the comparison between the profit margin in moving freight or people (on a charter flight) showed there was more to be gained by keeping the hull in PAX config.
DA did have a cargo operation of sorts with the B707 but as you probably know the cargo market back then was littered with airlines that went bust because they only dealt with cargo. Anglo Cargo Airlines, Scimitar, Red Coat.
Another try on the cargo front was a DA HS748 (G-BIUV) converted to a cargo aircraft. There's a great book titled, "The Spirit of Dan Air" (£15) and on page 103 is a black and white photo of a jet engine being loaded in through the big twin-doors. Of course some of the standard 748 pax version was used during the night as freighters for the Post Office, and then converted back to the PAX version for the inter-city runs during the day.
The DeH Comet's that DA bought were not economical back then and it was folly to think of them trying to break even by running them on two engines
whilst even considering a freighter role for one or two.
I can vouch that the RAF Nimrods did cruise around on two engines at low level (eg below 10,000') - when below the critical weight - whilst on recce patrols.
I know of an instance when running on two, a BEAR (Russian LRMP aircraft) arrived on scene and it outran the Nimrod, whilst the other two engines were lit to give chase!
I cannot vouch what the current version of the Nimrod does to conserve fuel in loiter situations.
TG