Afternoon PDT Grimmund,

Any automatic system can fail to do its designed function for any number of factors. A sensor fails or the connection between the sensor and computer fails. In a story about an airliner that crashed the crew allowed two passengers to handle the controls. Unfortunately, the crew was not told during training that the auto-pilot could be partially or completely disengaged when the control yoke was manipulated in some way.

There is always a chance that a gust of wind or other factor could cause a ship hovering to move at the worst time in the direction to cause the most havoc.

Tom Rux

From: "Grimmund" <xxxxxx@gmail.com>
To: "TML" <xxxxxx@simplelists.com>
Sent: Monday, August 14, 2017 12:50:57 PM
Subject: Re: Landing vs hovering (was Re: [TML] What class of Port is this?)

On Sat, Aug 12, 2017 at 3:01 PM, <tmr0195@comcast.net> wrote:

Afternoon PDT,

Looking at the use of auto-pilot on aircraft and ships at sea the pilot or ship's crew member is monitoring the system. I would expect that a crew member qualified as a pilot would be monitoring the system just in case something goes wrong.

Both true. However, both of those, an airplane at cruising altitude, and a ship at sea, have plenty of maneuver room. Small course changes due to environmental effects can be easily corrected before any significant issue comes up.

If your ship is hovering a half-meter off the ground, that's a little more dicey.

On the other hand, a ship has a lot of mass to move. That would tend to mitigate whatever force load you're getting with simple environmental factors like wind.

On the gripping hand, if your ship is hovering, it's maintaining station with drives or CG, not friction, and potentially easier for the wind to push around, particularly if your stationkeeping software is slow to react.

http://www.engineeringtoolbox.com/wind-load-d_1775.html

That said, wind load is a lot less than river current load, because the air is not nearly as dense as the river. So stationkeeping is less of a problem for a starship than it would be for a river ship.

And presumably, even if the stationkeeping software is slow, due to the mass of the ship, you'd have to have some pretty ridiculously high gusts to put on enough momentary load for the system to not be able to keep up.

Just my .02 CR

"Any sufficiently advanced parody is indistinguishable from a genuine kook." -Alan Morgan

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