Steam Airships

Modern airships in the DSRRed use steam as both the Lifting Gas and as the source of propulsion in their engines.
== Lift ==
The lift of steam at 100°C is 6.26 Newtons / Metre Cubed. This is around 2 time the average lift provided by hot air and around 60% of the lift provided by Helium. However, it is much more accessible than Helium, although the need for re-boilers is a distinct disadvantage. 
=== Re-Boilers ===
The main disadvantage of using steam is the need for a "re-boiler" to re-heat the steam after it condenses into water. The re-boiler aboard an airship usually has two variations: a "pure re-boiler" or a "superheating re-boiler". A pure re-boiler will only take in the condensed water that pools at the bottom of the gas bags, boil it and pump it back into the gasbags, whilst a superheating re-boiler will take in both steam and the pooling water, boiling the water and superheating the steam. Superheating the steam decreases the rate at which it condenses and increases lift more efficiently than boiling water, os in these designs the aim to boil water as little as possible. 
As these re-boilers are usually enough to keep p with the speed the water condenses with slight overhead, it can take a long time to fill an airship's gasbags before takeoff using only them. For this reason, most airship docks will have a larger boiler available to quickly fill gasbags if the steam has been allowed to condense.
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Category:Airships