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Author Topic: Steam Crossbow 101  (Read 11093 times)
Wayland2002
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« Reply #25 on: January 20, 2009, 12:41:31 am »

I can't see how (even with the best suspension of disbelief) how a steam mechanism is supposed to lock the nut, draw the prod, secure the string, insert the bolt and release the trigger. Even a repeating ballista required some element of human intervention.

To be honest I thought you were describing a device that shot an arrow/ bolt by using steam pressure, hence a steam canon.

I'm sure that a steam driven mechanism could do the job. Plenty of cams, levers and clever gear trains, plus worm screws and pulleys should do the job combined with a gravity fed hopper magazine. (e.g. have the string when drawn back enough released automatically because of a cam releasing the trigger).... Just there's no way on earth you'd get it portable or even a hand weapon.

I can see where you're coming from but I'm not sure it would work, the Chinese invented a repeating crossbow that had a lever on the top that drew the string through a magazine, picked up a bolt and then released it. The problem was though that the draw weight of the prod is very low so it has a limited range and penetration power.
To be honest there would be little or no point in constructing a steam powered crossbow when a hand drawn one works perfectly well.
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Dr cornelius quack
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Arrant Carney. Phmebian Cultural Attache.


« Reply #26 on: January 20, 2009, 12:45:05 am »

I can't see how (even with the best suspension of disbelief) how a steam mechanism is supposed to lock the nut, draw the prod, secure the string, insert the bolt and release the trigger. Even a repeating ballista required some element of human intervention.

To be honest I thought you were describing a device that shot an arrow/ bolt by using steam pressure, hence a steam canon.

I'm sure that a steam driven mechanism could do the job. Plenty of cams, levers and clever gear trains, plus worm screws and pulleys should do the job combined with a gravity fed hopper magazine. (e.g. have the string when drawn back enough released automatically because of a cam releasing the trigger).... Just there's no way on earth you'd get it portable or even a hand weapon.

I can see where you're coming from but I'm not sure it would work, the Chinese invented a repeating crossbow that had a lever on the top that drew the string through a magazine, picked up a bolt and then released it. The problem was though that the draw weight of the prod is very low so it has a limited range and penetration power.
To be honest there would be little or no point in constructing a steam powered crossbow when a hand drawn one works perfectly well.


You feeling alright?

Dr. Q.
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Wayland2002
Snr. Officer
****
United Kingdom United Kingdom


« Reply #27 on: January 20, 2009, 01:04:56 am »

I can't see how (even with the best suspension of disbelief) how a steam mechanism is supposed to lock the nut, draw the prod, secure the string, insert the bolt and release the trigger. Even a repeating ballista required some element of human intervention.

To be honest I thought you were describing a device that shot an arrow/ bolt by using steam pressure, hence a steam canon.

I'm sure that a steam driven mechanism could do the job. Plenty of cams, levers and clever gear trains, plus worm screws and pulleys should do the job combined with a gravity fed hopper magazine. (e.g. have the string when drawn back enough released automatically because of a cam releasing the trigger).... Just there's no way on earth you'd get it portable or even a hand weapon.

I can see where you're coming from but I'm not sure it would work, the Chinese invented a repeating crossbow that had a lever on the top that drew the string through a magazine, picked up a bolt and then released it. The problem was though that the draw weight of the prod is very low so it has a limited range and penetration power.
To be honest there would be little or no point in constructing a steam powered crossbow when a hand drawn one works perfectly well.


You feeling alright?

Dr. Q.

On the grounds of practicality and transportability it's not needed.......................... but a steam canon, now that's another matter. With super heated, compressed steam you could launch a projectile a considerable distance.
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HAC
Steam Theologian
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HAC_N800
« Reply #28 on: January 20, 2009, 01:17:19 am »

Steam cannon -easily doable, but he biggest problem , from what I have read, is the release valving. You want an extremely fast openig and closing valve, and that was one of the sticking points whan this was tried. The Holman MKII Projector was the last somewhat sucessfull steam powered weapon. It was designed to be used on armed trawlers inWWII, and was designed to fire (project) a Millls bomb at enemy aircraft, It was fed by the trawler steam engine boilers. In theory the design was solid. In practice, the early (MkI)versions were plagued by trigger valving and  steam condenstation problems. The modified and workable MkII versions were fitted to a wide variety of ships, from destroyers to minesweepers and motor gun boats. The range, with a Mills bomb weighing 1.6 pounds was between 600 and 1000 feet, depending on the boiler pressure of the vessel fitted.

Cheers
Harold
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The Emblasochist
Deck Hand
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United States United States


« Reply #29 on: January 20, 2009, 02:26:43 am »

I can't see how (even with the best suspension of disbelief) how a steam mechanism is supposed to lock the nut, draw the prod, secure the string, insert the bolt and release the trigger. Even a repeating ballista required some element of human intervention.

To be honest I thought you were describing a device that shot an arrow/ bolt by using steam pressure, hence a steam canon.

I'm sure that a steam driven mechanism could do the job. Plenty of cams, levers and clever gear trains, plus worm screws and pulleys should do the job combined with a gravity fed hopper magazine. (e.g. have the string when drawn back enough released automatically because of a cam releasing the trigger).... Just there's no way on earth you'd get it portable or even a hand weapon.

I can see where you're coming from but I'm not sure it would work, the Chinese invented a repeating crossbow that had a lever on the top that drew the string through a magazine, picked up a bolt and then released it. The problem was though that the draw weight of the prod is very low so it has a limited range and penetration power.
To be honest there would be little or no point in constructing a steam powered crossbow when a hand drawn one works perfectly well.


You feeling alright?

Dr. Q.

On the grounds of practicality and transportability it's not needed.......................... but a steam canon, now that's another matter. With super heated, compressed steam you could launch a projectile a considerable distance.


Well, of course its not necessary, or even smart.  But I never claimed to be either.  And for the sake of discussion, the bow I was hoping to design was meant to not have a string at all.  If you want an idea of what I got my inspiration from, think the crossbow used in the movie Van Helsing, cause that's pretty much what I was thinking.  And I know that that was most certainly NOT steam powered.  And if anyone was interested, the purpose of the weapon was to shoot a bolt no more than about 75 yards at speeds of about 75 miles per hour.  It really changes very little, because the drum of the bolts is still driven by some mass of high pressure air, and the bolt is still propelled by pressure of air.
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Dr cornelius quack
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United Kingdom United Kingdom


Arrant Carney. Phmebian Cultural Attache.


« Reply #30 on: January 20, 2009, 02:38:31 am »

Yeeesh!

Never mind the steam, the whole thing's going to be dangerous!

What exactly is the pupose of this little toy?

Dr. Q.
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The Emblasochist
Deck Hand
*
United States United States


« Reply #31 on: January 20, 2009, 02:42:01 am »

My purpose?  Well, to learn things though my efforts and build a working prototype of something unusual.

The character's purpose would be to use it for bear hunting, and the like.
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Dr cornelius quack
Rogue Ætherlord
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United Kingdom United Kingdom


Arrant Carney. Phmebian Cultural Attache.


« Reply #32 on: January 20, 2009, 03:00:17 am »

Well, I have to tell you, if that's what you build, then it's not a prop, it's a weapon and I find myself loosing interest in helping any further.

Think carefully before you procede with this.

Dr. Q.
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The Emblasochist
Deck Hand
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United States United States


« Reply #33 on: January 20, 2009, 03:04:06 am »

I can't be mad at ya if you don't want to be party to the development of a fully functional weapon.  Thanks for the help you have provided.
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Zer0
Officer
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United States United States


« Reply #34 on: January 20, 2009, 03:31:12 am »

Being a card carrying member of the NRA I have no qualms about you trying to make a workable weapon, as long as you have no intention on using it on a human.  From the options listed, it seems possible, though more dangerous and difficult then necessary.

But.. !! ISNT THIS the mad scientists spirit? the true form of a creative madman bent on a single goal , to hell with the consequence? I say push on sir.. but in a well ventilated and equally uninhabited area.
« Last Edit: January 20, 2009, 04:07:57 am by Zer0 » Logged

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Zer0
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« Reply #35 on: January 20, 2009, 03:55:46 am »

http://www.lateralscience.co.uk/perkgun/index.html


CHECK THIS OUT!! very cool even if not that portable
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jringling
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convicted Rogue and Vagabond…long story…


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« Reply #36 on: January 20, 2009, 03:55:48 pm »

Hmmm...
something like this?

http://brassgoggles.co.uk/bg-forum/index.php?topic=13496.msg264639;topicseen#new
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akumabito
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« Reply #37 on: January 20, 2009, 09:17:03 pm »

Steam cannon -easily doable, but he biggest problem , from what I have read, is the release valving. You want an extremely fast openig and closing valve, and that was one of the sticking points whan this was tried.

Just thinking aloud here, but wouldn't a similar valve system as used on some simple gas-powered airsoft guns work? The valve is relatively simple; held closed by a spring, and struck by the gun's hammer to open it for just a fraction of a second.

Are there any problems preventing such a setup to work with steam? Aside from the rather obvious strengthening and scaling up, naturally..
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jringling
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« Reply #38 on: January 20, 2009, 09:27:50 pm »

There has to be some sort of high pressure valve system out there. I’m not sure if it is urban legend or not, but I have heard of an air cannon used at Pumkin Chunkin events that operates at 1000+ PSI.
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Alexander Edmund Clough
Snr. Officer
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United Kingdom United Kingdom



« Reply #39 on: January 21, 2009, 12:53:22 am »

The pumpkin cannons that run at high pressure DON'T USE STEAM.

They are compressed air or CO2.

I believe they use scaled up versions of some of the valve designs that compressed air spud guns have been using for a while. Unfortunately, I can't remember what the particular valve design I'm thinking of is called, so some googling might be needed. (the valve in question works by using air pressure to prevent the compressed air in the tank being released down the barrel. You fire the cannon by releasing the pressure on the one side of the valve which allows the air in the tank to blow a flap back and enter the barrel)
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jringling
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« Reply #40 on: January 21, 2009, 02:33:37 am »

I know they don't use steam! If they did, they would be called steam cannons! Wouldn't the vavle system be the same? I understand steam is not just pressure, but also heat, otherwise, what is the difference?
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akumabito
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« Reply #41 on: January 21, 2009, 06:26:22 pm »

The pumpkin cannons that run at high pressure DON'T USE STEAM.

They are compressed air or CO2.

I believe they use scaled up versions of some of the valve designs that compressed air spud guns have been using for a while. Unfortunately, I can't remember what the particular valve design I'm thinking of is called, so some googling might be needed. (the valve in question works by using air pressure to prevent the compressed air in the tank being released down the barrel. You fire the cannon by releasing the pressure on the one side of the valve which allows the air in the tank to blow a flap back and enter the barrel)


Sounds like a piston valve.
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akumabito
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« Reply #42 on: January 21, 2009, 06:29:08 pm »

I know they don't use steam! If they did, they would be called steam cannons! Wouldn't the vavle system be the same? I understand steam is not just pressure, but also heat, otherwise, what is the difference?

I'm kind of wondering that myself. There are rapidly opening air valves that are good for several hundred PSI - and I can't really think of any good reasons such s design couldn't be scaled up to cope with several 1000 if necessary. I know steam and compressed gas aren't the same thing, but I don't quite get why appropriately strengthened pneumatic valves wouldn't work. Arguably, hydraulic equipment could be better suited for use with steam, but I don't really know of any hydraulic valves that open quick enough.
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Alexander Edmund Clough
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United Kingdom United Kingdom



« Reply #43 on: January 22, 2009, 01:34:01 am »

Piston valve. That's the one. Thanks akumabito!
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Sir Nikolas Vendigroth
Captain Spice
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« Reply #44 on: January 22, 2009, 02:48:04 pm »

What you're describing sounds like a repeating air rifle, which simplifies matters a lot.

It's still a terminal idea, though. It's a terminal idea because if you try and work with live steam, it may well be the last idea you ever have.
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alfa1
Zeppelin Captain
*****
Australia Australia



« Reply #45 on: January 24, 2009, 07:05:11 am »

I'm rather amused that the builder, as he confesses, knows nothing about steam power and has no experience with it.
but...
as his very first foray into the field he plans to build a device so complex that nobody in human history seems to have accomplished it before him.

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Zer0
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United States United States


« Reply #46 on: January 24, 2009, 12:43:54 pm »

I'm rather amused that the builder, as he confesses, knows nothing about steam power and has no experience with it.
but...
as his very first foray into the field he plans to build a device so complex that nobody in human history seems to have accomplished it before him.



The idea has been done.. all be it with hoppers and bullets instead of belts and darts. it was also mentioned that he would settle for a look-a-like... and...

there always has to be a first.. and sometimes they come from the most unlikely people. Steampunk is all about fantasy.. here you have a possible hero destined to conquer or fail.. what is better story sir?

I for one cheer him on.
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Otto Von Pifka
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« Reply #47 on: January 31, 2009, 04:40:14 am »

well if all you want is the look of a steam powered x-bow, then compressed air or CO2 is the easiest way to go.

I myself have made a simple prototype air rifle that at only 250psi fires a .44 slug with the terminal energy of a .22 long rifle. that simple design uses a well polished ball valve with springs to fling it open, the trigger simply holds the valve shut. it's just a collection of pipes, fittings and springs but it's able to blow a hole through half inch marine plywood.

eventually I will return to the design and make a working model similar in look to the air rifle carried during the lewis and clark expedition. the only real difference will be that it's CO2 powered instead of compressed air.

now as far as lethality goes, there are many people who hunt with big bore air rifles, taking game as large as deer. I'm not talking about just wounding and following them until they bleed to death, they're capable of one shot, one kill power.

as for your plans, opening up the bore with bigger pipes, you could simply put a gas check on the rear of the prods and fire them out like a piston.

listening to the back story you mentioned, I would consider maybe a conventional crossbow design with an added steam bow barrel added below the standard setup. sort of like a grenade launcher mounted on an assault rifle, both in looks and theory.

even regular crossbows are quite powerful, a friend made one using a fairly straightforward medieval design and it managed to ricochet a bolt off a forklift and a metal stand and still pass through almost the full length of a 12pack of soda. what a mess!
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The Emblasochist
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« Reply #48 on: January 31, 2009, 04:55:37 am »

That bit about putting a second, air/CO2 powered dart propulsion system sounds even better than making it single shot steam all the way...  Its a lot like an over an under shotgun in concept.  I think that could be done without much difficulty.  Thanks for the idea!
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flimflam
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« Reply #49 on: February 09, 2009, 04:28:36 am »

surprised no one has said this, but if it has no bowstring isn't it really just a steam powered dart gun?
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