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By Dermot Tynan, about 8 years ago.

After a lunchtime conversation with a friend of mine, I ditched some of the earlier design considerations around message-passing and MQ-based systems in favour of the NoSQL database Redis.

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The new rudder

By Dermot Tynan, over 8 years ago.

Thanks go to Colman Corrigan for designing and building the keel and rudder. The keel follows the traditional NACA shape, with a rounded leading-edge, tapering off to a narrow trailing edge. It is approximately a 6318 shape, with the maximum width being about 36% of the length of the cross-section. Overall, the keel is coming in at about 750mm from hull to the end of the bulb, and about 240mm from front to back. That's a 3:1 aspect ratio.

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Rudder box with gears

By Dermot Tynan, over 8 years ago.

This photograph is of the new rudder box with a NEMA17 stepper (underneath) and the two gears. The smaller gear is on the stepper and the larger, quarter gear will be clamped to the rudder shaft. It's a 4:1 ratio and the rudder gear is 90 degrees so one complete turn of the stepper will bring the rudder from end to end. That's plus or minus 100 steps.

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Rudder with filler.

By Dermot Tynan, over 8 years ago.

This is a quick photograph of the rudder stock once it was filled with a mixture of West System 405 microfibres and West System epoxy. I formed a basic mould out of wood, added "shrink wrap" to prevent the filler from sticking to the mould, dropped in the rudder stock frame (see below) and then poured in the filler. It took around a week to fully harden, and I will sand and paint the finished product.

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Good morning, Mother!

By Dermot Tynan, over 8 years ago.

As of about an hour ago, Igor and Mother exchanged communication. It was awkward, stilted communication, like a first date, but they talked! One of the issues with the RS232 stream is that the kernel is chatty. I've suppressed a lot of the boot-up messages, but there are still all those /etc/rc startup messages. As the ALIX board only has one serial port, those messages are sent to Igor. To avoid sending Igor into a tail-spin, or more importantly, sending the boat into a tail-spin, Igor ignores all RS232 output when Mother boots, until the magic word is sent over the wire. The magic word is XYZZY. Anyone want to try and figure out where that comes from?