Brown Brothers

Steam and Other Catapults




Alex Dow

Fife, Scotland

Alex Dow reply to Alastair Adams' Recollections 15 about steam catapults.

Alex wrote:

Steam Catapults

"If you take a look at this Navy History site, you'll see that Steam Catapults were basically a post-WW2 innovation, involving Brown Brothers, etc."

Steam Catapults

"Alistair's father was probably working on the earlier Hydraulic Catapults; and I think that there were not many of those in the Flight Deck.

He could also be confused with the short-ramp variety used from WW1 and eventually epitomized by the use with Hurricats - Hurricanes modified for ramp take-off from the Merchant Aircraft Carriers, where there was only one plane aboard, one take-off ramp and NO Landing Deck.  So, the plane was normally ditched unless close to land."

Brown Brothers

"Brown Brothers had a model of the earlier inter-war version, complete with a model Walrus Amphibian. I helped to demonstrate this and their Hydraulic Steering Gear at the 1949 Parish Industries Exhibition at McDonald Road Church."

Prop-driven Aircraft

"Prop-driven aircraft create a fair amount of lift when stationary in windless conditions, just by the air flow created by the prop/s over the wings.

If you ever flew in such a plane, you would notice that even on a calm day, the aircraft would lift and fall in its own airstream, when revving up at the start of the runway. In part it is also the reason for the ground crew member sitting on the tail plane when taxiing over the airfield, or clinging on to the wing tips."

Jet Aircraft

"The air streams from jet aircraft go nowhere near the wings, whether inboard like the Comet or outboard like most modern airliners. Hence it was the introduction of pure jets to naval flying that forced the development of the steam catapult."

Hydraulic Catapults

"The earlier hydraulic versions required totally separate plumbing, compressors, hydraulic reservoirs and had limited travel from the need to fully contain the pressurised hydraulic oil, to minimise/avoid the loss of the oil, particularly on to the deck and deck crew. It also took some time to 're-arm' the system for the next take-off, one plane at a time.

The oil, like most fluids, is virtually incompressible, so that you are dependent upon a small pressure vessel to achieve the drive."

Steam Catapults

"The later steam catapult could be plumbed in to the existing large capacity on-board boilers, using superheated water. When this is released in to the launch piston, it expands up to 800 times the volume, so maintaining a positiverive to the piston and aircraft, through the full stroke length.

Any losses from the system rapidly pass through the water vapour phase to water, cooling simultaneously, so much less of a menace on the deck and for the deck crew.

Some of the USA Nuclear-powered Carriers with four catapults can launch an aircraft every 20 seconds. The superheated water comes from the cooling system for the nuclear reactors."

Alex Dow, Fife, Scotland:  May 23, 2011


See also:  Leith during World War II -  Mini-Blitz

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