Entries from January 2008

Battery Beach Burnout—Electric Car Drag Racing

Friday night the boys and I spent some hours immersed in a weird mix of high-octane drag racing and electrical engineering geekery—the Florida Electric Auto Association took over a "run-what-you-brung" drag racing event as part of their Battery Beach Burnout weekend. The venue was one Countyline Dragway, an 1/8 mile strip of pavement in the middle of the woods in northwest Dade county. One of the competitors brought this homebrew 240 volt electric bike, with 20 batteries driving a shifter kart tire hard enough for a smoky burnout - in the picture I'm holding the brake down to keep the bike from moving as he tensions his drive chain, which unfortunately broke on his first run of the night.

The following picture is of a Porche 912 with an improbable modification: two DC motors inline and hanging out of the back like a rocket engine. This car set the Countyline Dragway electric record at 67 miles per hour at the 1/8 mile.

Mjolnir Pendants—Yet Another Skill for My Mythbusting Résumé (New Year's Eve Part 3)

I made some Mjolnir (that would be the hammer of Thor for those who don't speak pagan-geek :) ) pendants for viking party costumes. It was also an opportunity to try my hand at sculpting and moldmaking, bringing me one step closer to living the life of a mythbuster—that is, a mythbuster without his own television show. I based the design on this one (found on google images); for the price, I probably should have just bought that one instead, but that's not really in the creative spirit of this whole New Year's Eve theme party thing.

The first step: I melted down some old bits of candle wax and cast them into a puck shape, from which I carved the original pattern using one of my very favorite tools, the X-Acto knife.

A Fireworks Mortar Rack (New Year's Eve Part 2)

One of the new elements in this New Year's Eve fireworks show was this 16-shot mortar rack, designed to accommodate the "festival ball" type of readily available mortar shell. The tubes are HDPE with a 1.875 inch bore, available from Skylighter at $27.25 for a group of six. HDPE is really the best material for this application—do NOT use PVC, as it will shatter into dangerous shrapnel if the shell fails to clear the tube and detonates inside. Certain types of cardboard launch tube, available from pyro suppliers, might be acceptable but I have no experience with this so you take your own risk if you choose to use it. The Skylighter HDPE tubes have a wooden plug at the bottom—I drove stainless steel wood screws into this plug from the base of the rack to secure the tubes.

The rack itself I constructed from various bits of hardware store lumber. Since this rack is deployed outside, in potentially wet environments, I painted it with several coats of Kilz primer, then glossy black exterior latex (glossy to make cleaning off any powder, soot, or dirt easier). I also mounted two carrying handles on either end.

During the New Year's show, this rack was loaded with a mix of Black Cat "Gold Class" spherical shells and their "Fort Knox" cylindrical shells. One row of eight was electronically detonated using my computer-controlled firing board (of which more anon), while the other side was lit with a blow torch, like most of the fireworks that night.

From the Fury of the Norsemen, O Lord Save Us! (New Year's Eve Part 1)

New Year's Eve 2007 was the latest in what has become a Martinson tradition: a themed costume party. The theme this year? Vikings! As always, this party involved a great deal of creative work beforehand in making the costumes, props, fireworks show, and all the rest of what our guests have come to expect out of a not-so-typical New Year's Eve. I can't publicly thank everyone responsible for these preparations, but you know who you are, and I know what you did. Thank you all. This post (and the ones to follow), however, is more for the benefit of those who weren't at the party, but are interested in some of the projects completed for it. First, my viking shield:

This is probably the only costume item that bears any similarity at all to actual viking kit, or at least measures up to a reasonable re-enactor's standard. Yes, it is plywood (11/32") rather than joined planks, and the fanciful dragon motif (taken from a shield on display at the Norway pavilion in EPCOT center) was probably never seen in actual dark age combat, but other than that, it's not bad. The plywood blank I cut out with a jigsaw. The steel boss was made by an armourer named Mad Matt (it's the "satin-finished" round boss available on his site)—a solid, economical choice I'm very happy with. I also applied an edge-banding of 3" wide rawhide strips (soak a large rawhide dogbone till it unravels, apply when moist and flexible) nailed over the edge with blued carpet tacks. The grip in the back picture is just a bit of hardware-store mild steel bar, drilled and riveted through to the boss.