User:Jeff Chan/Seadrome

Description

Seadrome was a proposal by Edward R. Armstrong from 1927 through 1946 to build a series of floating airports in the Atlantic in order to enable trans-ocean passenger flights between U.S. and Europe before long distance, unrefueled flight was possible. Aircraft would land, refuel, and fly to the next Seadrome in a series of hops. Two things stopped it from happening: the great depression and improvements in aircraft range. Nonetheless, the Seadrome design appears to be very interesting and thoughtful. It was designed to be maximally stable possible in open ocean waves.

Detail

• Overall Specifications (length, width and height are about the same as a modern aircraft carrier +10% or so):
  • Length: 1200 feet
  • Width: 400 feet at center, 200 at ends (i.e., narrower at fore and aft decks, much like an aircraft carrier). We could build to different shapes.
  • Draft: variable from 50 feet with ballast/heave plates retracted into vertical float columns, 160 foot draft with ballast/heave plates fully deployed
  • Air gap: 70 feet (or possibly 70 foot deck height, but images look like the deck may be 20 to 30 feet above that.)

Requirements Analysis

• Safety - should be relatively stable in heave, pitch, roll. Minimal wave response in all directions. 70 foot airgap is nearly double ClubStead, but possibly still too low for rogue waves. Decks could be made higher, for example by scaling up the entire design.
• Comfort - could be very stable in waves. Large horizontal deck area may feel like land or a large city block
• Cost - ten million dollars per Seadrome was quoted in the 1930s. Call it half a billion dollars or more now.
• Pretty - Industrial looking, kind of like a giant pier floating in the ocean, or stationary aircraft carrier, or a really wide oil platform
• Modular - probably not modular. May be possible to raft them, or join with bridges. May require precise station keeping that should be possible with electric thrusters, accelerometers, computer control, etc. If joined or bridged, dispersal for storms should be quite viable.
• Cargo - Was designed for housing people, storing aircraft, fuel, water, food, supplies.
• Free Floating - Yes
• Scalable - Smaller versions can be built, but for best response to full size ocean waves, it needs to be built to full scale. Subsections can also be built. Originally a middle third of Seadrome was meant to be built as a demonstration prototype. Jeff Chan and friends built a 1/100 scale model of a foredeck at Ephemerisle 2009, but the materials were too heavy for its scale. Lightening efforts are underway, but a model with lighter materials would be a better test. Heave response of a single model column was excellent, settling immediately, possibly near critical damping. 1/3 of one, scaled down, may make a good Baystead.
• Standards - Unprecedented design overall, however, steel construction techniques and standards could be very similar to ClubStead, semisubmersible oil platforms, etc.
• Mobile - Designed to be slowly mobile, possibly self-deploying. Meant to be anchored and point runway into the prevailing wind, swinging around massive anchor. Seasteads may not need anchor.
• Draft - Variable draft. Ballast/heave plates retract up into vertical columns (nesting mostly inside them) for operation in shallower waters such as launching from construction near shore. Should reduce draft to about 50 feet. Fully deployed draft is 160 feet.