Tuesday, November 24, 2009

Putting Steam Power Where It Wasn't

As a writer of steampunk (and general science/engineering nerd) the most entertaining theories I come up with tend to involve making a piece of equipment steam powered when it wasn't originally. Well, those and some of the nutball ideas that pop into my head where my characters are concerned ... but I digress.

The polybolos, as you may or may not know, was a siege engine in use during antiquity that could fire multiple arrows in rapid succession through use of its chain drive. The mechanism in question is a flat-link chain attached to a windlass, the oldest known use of a system that was considered an invention of Signore da Vinci's.

From (where else?) Wikipedia:

"When loading a new bolt, the windlass is rotated counter-clockwise with the trigger claw raised; this drives the mensa forward towards the bow string, where a metal lug pushes the trigger under the trigger claw, which is closed over the string.

Once the string is locked into the trigger mechanism, the windlass is then rotated clockwise, drawing the mensa back, drawing the bow string with it.

A round wooden pole in the bottom of the magazine is rotated down toward the mensa (cradle that holds the bolt) as it is drawn to the back of the polybolos, dropping a single bolt into the tray, ready to be fired. As the mensa is pulled farther back, it meets another lug like the one that locked the string into position, this one pushes the trigger and automatically fires the polybolos, and the process is repeated. The repetition provides the weapon's name, from the Greek πολύ - poly "multiple, many" and -βόλος - -bolos "thrower" (from βάλλω - ballo "to throw, to hurl"), or simply a repeating weapon."

As the above description shows, the polybolos already operated with mechanical action, which makes it a little easier to adapt steam power onto it.

My theory (and yes, this will be used in the new project) is to attach a steam-powered mechanism to the base of the machine accompanied by piping and gear work that turns the windlass at a speed greater than regular mechanical motion can achieve. Also, a steam-powered polybolos could be made to rotate automatically on a horizontal axis, which would thus eliminate a suggested complaint of it being "too accurate."

There's also the potential for steam power in ballistas and gastraphetes (a belly bow) among other possibilities.

As always, your thoughts are appreciated.


L. T. Host said...

My thoughts are:

Dang, this Matt guy is GOOD!


No but seriously. You never cease to amaze me.

Bane of Anubis said...

Very, very cool.

Renee Pinner said...

Where were you when the Wild West, or Renaissance Europe, needed you?

Matthew Delman said...

L.T. --

Sheesh ... again with the compliments. Oh, and I got your reply, by the way. Thanks for the suggestions.

Bane --

Yeah, the physics of making it happen with extant materials is the really interesting part.

Renee --

Having the whole of human scientific advancement at my fingertips (I love the Internet) is the only reason I can come up with these theories. Well, that and the great inventors of the past doing their thing.

L. T. Host said...

Well, you deserve them.

Also: I feel a little sheepish now, bowing down before your use of actual Greek alphabet characters in your post. *sigh*

Anita Saxena said...

The engineering stuff is a bit over my head. But anything with steam and five arrows sounds pretty cool.

Stephanie Thornton said...

Wow- that is a cool idea! Cleo would be proud!

And I've been super swamped at work, like migraine inducing swamped. So I just got your email. A response is on the way!

Adam Heine said...

No new thoughts. This is just super-cool. Makes me want to do world-building again.

Matthew Delman said...

Stephanie --

Just read it and replied again.

Adam --

I loves me some world-building. Probably why I write fantasy/sci-fi instead of any other genre. Way more fun to craft another place and time.