Fwd: sea launched maned vehicle design
Bryan Bishop
Date: Wed, Oct 3, 2012 at 10:50 AM
Subject: [AR] sea launched maned vehicle design
To: "aro...@exrocketry.net" <aro...@exrocketry.net>
I have been happy to see Copenhagen Suborbital’s successful sea launch operations. Based on the demonstrated feasibility of sea launch, I would like to propose a manned vehicle design that specifically takes advantage of it.
Blowing the nose off a rocket sucks. We are still doing it with our Stig rockets, but it really doesn’t feel right.
Multi stage parachute recovery systems also suck, adding several additional things that can go wrong.
It seems like it would be plausible to have a high fineness ratio vehicle that uses a single stage, rear ejection parachute / ballute so that it enters the water nose first at a human tolerable rate of deceleration. There is a body of work on air dropped torpedoes that is probably relevant, although a space vehicle would presumably be designed with a significantly sharper nose and higher fineness ratio.
The passenger would be as close to the nose as possible to minimize any “slap effect” from a water entry that wasn’t exactly normal to the surface. The ride position would probably be bobsled-like, with lots of padding and restraint. It wouldn’t be a ride for you grandmother; more like cliff diving than commercial air transport.
I imagine something a bit wider than Stig-B http://twitpic.com/b0aw10, with the fineness ratio of Stig-A and a sharper nose with large windows. Pack two 5k engines on the base, leaving space for two redundant rear ejection parachutes or ballutes in armored deployment tubes.
Launching over water makes failures very early in the flight more survivable. Launch would be at a slight angle to clear the launch infrastructure. It might even make sense to spend some performance to allow launch at a lower angle, and have the vehicle pull up, so failures in the first couple seconds would result in a nose first water entry instead of a side slap.
The vehicle remains passively stable through the entire non-powered part of the flight. Deploying the parachute doesn’t involve wrenching the vehicle around. You still have to make sure you don’t deploy it at an unreasonably high dynamic pressure, but the actions for all emergencies throughout the entire flight are just: shut off engine, wait for apogee (or sensible atmospheric entry if near space), deploy parachute. If the first parachute fails, deploy the backup.
With only a single parachute stage, full redundancy is reasonable. Once there is a good deployment coming down around 200,000’ altitude, the entire rest of the ride is completely passive.
The rest of the Armadillo guys hate the idea of operating on water, so I would be happy to see CS or anyone else pursue the plan. Build some boilerplate mockups and drop them from helicopters, eventually putting a volunteer in them and ramping up the drop altitude and conditions…
Thoughts?
John Carmack
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