Power-egg

[citation needed] Project 651E, originally envisaged as a modification of the Juliett-class submarine, consisted of a small mostly self-contained additional 600 kW nuclear reactor, model VAU-6, the so-called Dollezhal egg.

This nuclear powerpack aimed to greatly prolong submerged capabilities of what was otherwise a normal diesel-electric submarine with long duration idling and underwater recharging of batteries.

[4] The Bristol Aeroplane Company devised an installation known as a "power egg" for the Hercules engine in 1938,[5] an example of which was exhibited at the 1938 Paris Aeronautical Salon.

[6] The Hercules installation was used on the Bristol Beaufighter, Armstrong Whitworth Albemarle, Vickers Wellington, Short Stirling, and Handley Page Halifax.

[12] In the United States Pratt & Whitney produced a R-2180-E Twin Wasp E "power egg" installation certificated in 1945 for use as an engine upgrade for the Douglas DC-4, however finding few buyers, it was eventually only used on the Saab 90 Scandia.

A BMW 801 Kraftei (power egg), being unloaded from a Gotha Go 242 transport glider. Russia, March 1943. Note the engine is already fitted with its cowling and cooling fan
A Merlin-powered, Beaufighter night fighter Mark II of No. 255 Squadron RAF at RAF Hibaldstow , September 1941, showing the Merlin Power Plants later used on the Lancaster.
Post-war CASA 2.111 (Spanish-built Heinkel He 111 ) with Rolls-Royce Merlin power plants of the type originally used on the Beaufighter II and Lancaster
Universal Power Plant (UPP) Merlin 85 installations on an Avro Lincoln
The later Universal Power Plant (UPP) Griffon installations on an Avro Shackleton .