78 Orbital Defence Railgun Spider

Finished: 23/9 2007
LWH: 68/30/68 cm, weight 2200g, pieces 2-3000

Build for Aaron M. Sneary's lame part/orbital defence contest on CSF running from 11/7 to 22/9 2007.
The task was to build something that could defend a planet from orbital attack using at least two parts from a list of selected lame parts.

Since I've been engaged in secret use of monorail tracks for an unfinished SHIP project, I was instantly attracted to the monorail tracks, and decided to make something with these as railgun-rails.
The idea kinda developed from there on a range of lame parts I've been hoarding, starting with these train-nose parts for the body or turret itself, these Jack Stone aircraft-noses for leg-sections (I actually had to buy a bunch more of these to have enough!), and lots of semi-lame 6x6 white dome-pieces (they are kinda useful, but slightly too large to be used in any quantity).

The gun stands 68 cm high in top position (that's a around over 2'3" for you imperials). The footprint is roughly 1 foot in diameter.

Gun:
The gun was one of the first things I started working on:
Basically I wanted "barrel"-section made out of two monorail tracks bottom to bottom, a short middle-section that would hold the clickhinge-rotating mechanism and two round 4x4 bricks on the exteriour that would look like strong hinges for the gun (accelerating something up to a fraction of light speed create A LOT of recoil), and a rear "reactor"-section that could balance the barrel.

It turned out to be pretty difficult to create a snot-construction that was able to both hold everything together, beside this, the only thing that was able to hold the barrel after I extended it with an extra pair of monorail tracks, was a couple of strong starwars technic clickhinges that demanded quite a lot of interiour space.
It did NOT help that I decided that the reactor part should be able to rotate as well, although this function turned out to be totally unnessecary (it looked best 90 degrees to the barrel regardless of it's position) so I scrapped this functionality when I finally had time to revise the gun right up to the deadline.

Turret/body:
Originally I had envisioned a flat turret with big roundish "clamps" to hold the fake 4x4 hinges, but I also wanted to be able to lower the gun to horizontal, and this wouldn't be possible without making them very high and ugly.
Instead I decided to "break" the rear part of the turret upwards and slot the two 4x4 round bricks into the bottom of the train-noses which I think turned out really well.

I forgot the central greeble-chunk when I was over in the park to photograph, so here's one of the usual bathroom shots.

The rest of the turret/body was pretty much aesthetic work, with greeble, cockpit and a lowered central part to make room for the gun.
The antennas on the right side of the turret was basically added to balance up the cockpit by creating something of visual interest on the right side of the turret/body.And of course to enable it to keep firing at larger targets even if the plantary sensoring and targeting system has been knocked out (sattelites, radio telescopes, defence fleet). Besides this, it gave me a good opportunity to use a second lame part from the list - a saddle - in an unusual role.

White dome removed so the leg can be folded in far enough to show the technique

Legs:
One of the things that I'm particularly proud of and which took me a lot of time is the legs: In the final 4th (and 4b) version, they're connected with a bionicle-balljoint hidden in the cener of the big white domes, which not only make it look like the legs are actually attached with giant 6x6 balljoints, but also enables the legs to move quite freely.

The problem with bionicle balljoints is of course strength, and the final legdesign was even weaker than the preceding clickhinge-based ones, and could not keep the model standing without extra support.
The sollution was pretty obviously to extend the leg into the interiour and add some sort of variable mechanism that could keep the legs from collapsing until the leg-extensions rested on top of the base frame.
Finding something that was strong and small enough, and above all capable to work in spite of the gaps and height-variations of the interiour frame proved to be quite a challenge, but after spending a lot of time pondering and experimenting, I simply couldn't come up with any better sollution than simply using technic axles and the friction from two 1x2 bricks with axlehole:
Originally I discarded the idea based because I feared that it was so narrow that it would just top over and make the legs fold, but this turned out not to be a problem when i finally got the interiour framework together - partly because the tips of the legs are flat, partly because the legs are spread out in 6 directions, which makes it really hard to push out of balance.

Unfortunately it turned out that leg-extensions really got in the way of each other with the narrow hexagonal shape I've found most aesthetically pleasing for the interiour framework. However, I was able create a shorter version using brackets and stud reversion for the middle pair of legs that even allowed me to make the connection between the turret and base-frame into a big solid pillar.
I kept the 4th version for the front and back pairs, primarily because these will be seen from the side in their full length and a shorter version would leave a large gap in an interiour that would be hard enough to fill up with greeble as it were.

Colour:
Originally I intended to brasso off the print on the lameparts but never found the time. But since the colours considerably increast the general lameness of the parts, and since they slowly began to grow on me, I decided to mirror the colours elsewhere on the model.

Antenna
I really like the rotating-technique I came up with for the radar-array: by sliding the arch through the saddle, it's able to follow the direction of the barrel.
Originally I made a brick-based brake system, but since it's quite large and need tightening all the time, I decided to use a (LEGO tm) rubberband instead.Originally I didn't thought I had a saddle lying around, and had abandoned the idea of using more lame-parts from the list than the monorail tracks.

Lamepart-count:

12 white 6x6 domes
7 Jack stone aircraft noses/tail
4 Train noses
1 saddle

I released a sneak-peak of the model on flick on September 22th, while the official announcement was made on CSF in this thread, and mentioned in the competition thread.