water boosting

[niju321]

Well, here’s an idea that popped into my head. It’s very poorly developed at this stage but it seems like it might work (to me at least) so I thought I might as well post it on this forum where there are lots of people who actually know what they’re doing.

Summarized Idea

My thought was that the powder “burn” would release quite a lot of energy in the form of heat. It is my understanding from what I’ve read about powder launchers thus far that this heat is basically wasted; it goes to heat the barrel, projectile, air, etc. I thought that perhaps this otherwise wasted heat could be used to boil some water and create some more pressure to launch the projectile with greater speed.

Technical Explanation and Justification of Idea

The idea, then, would be to utilize the heat that would otherwise be wasted in some way to launch the projectile with (hopefully) greater speed and thus better range. Given that the barrel in question is about 2.5 feet long and about 2.7 inches in diameter, this gives a volume of about 172 cubic inches or about 2.8 liters. From what I remember of my chemistry classes 1 mole of water gas, which weighs about 18 grams will occupy 22.4 liters at 1 atmosphere or about 14.7 psi. I’ve calculated (though imperfectly) that the energy needed to heat this water from 70ºF to the required 212ºF will be about 1440 calories. From the same series of calculations, and Google’s best guess as to the amount of energy released by the 1 ounce of gunpowder I plan on using will be approximately 26,817 calories, most of which, I assume, would be released as heat.

Would it be a good idea to perhaps use a balloon or other separation device to hold some water to be boiled by the heat of the powder burn? If my calculations are correct then there would be plenty of heat for at least 54 grams of water to be boiled rather instantaneously. This would produce 67.2 liters of steam under normal pressure, but of course the barrel, right before the projectile exits, would have 24 times less volume, hypothetically producing a pressure of 24 atm or about 353 psi in addition to the gas produced by the powder burn itself.

This seems like an easy way to use the heat already being produced by the burn to give me longer range or better fuel efficiency (defined, in my case, as the percentage of energy from the fuel that actually contributes to launching the chosen projectile). It would also have the effect of cooling the reaction and reducing the thermal shock the barrel would have to endure, hopefully prolonging its safe service life.

What are your thoughts on this? Is this even worth attempting?

[Double D]

I'm not sure this is relevant to this forum.  This is the Blackpowder Mortar and Cannon forum.

Are you aware of steam cannons made prior to 1899, since that's the basic principle you are talking about?  We could put you on topic that way?  

But as far as modern devices go it would be off topic.

[niju321]

Sorry about the inconvenience, I assumed that since I would be using this in a blackpowder cannon it belonged in the blackpowder cannon forum. Where would be a better place to put this post?

[Double D]

Put it here, and be sure to mention the black powder and the history everynow an then.  There has  to be a pre 1899 application.

We had the same dilemma when discussing electric ignition.  Finally someone found reference to electric ignition going back to the Civil war.

We have a very diversified group here and some one will come up with a way to fit you in to the legal description.

[ShadowMover]

niju321,   I would suspect this is the right forum, but I''m guessing they don't understand your concept.  I'm not sure it would work as planned either.  The whole concept of propellants is a large quickly generated volume of gas, sufficient to keep a continuous pressure on the projectile, while it travels down the bore, while not exceeding the strength of the bore. No doubt the water would generate more gas, as steam, but it would have to be at a lower temperature, because to boil every ounce of water would pull a huge amount of heat from the burning gasses. The pressure on the projectile is directly proportional to it's temperature (Boyles Law), and cooling the gasses would also slow the burning of the powder, generating less gas to propel the projectile. A lot of steam exiting the barrel after the round would represent a lot of heat wasted. Steam has a very high 'specific heat', which means it takes a lot of heat to change it's temperature.
A lot of good ideas have had 'cold water' poured on them though.  :lol:
Why not try it out and tell us how it worked?

[Cat Whisperer]

As with all experimentation, there are variables that will vary without your prediction of it.  Therefore plan on things coming unglued at the most inappropriate time by making provision for the explosion.

Interesting idea.  I think it's proven with the water injection in race cars.  Controlling it is the issue.  How do you control the process that only occurs inside the barrel for a few milliseconds?  Doable, not easy, but some simple experiements could be put together.

In general we like to keep to the tried and true so that folks don't get killed and y'all don't get a chance to read about the carnage in the national news.  But if you have the right facilities for testing the theory, knock yourself out.

Most of us don't have those facilities - but would be interested in the results.

[Double D]

Just as long as meets the board criteria continue.

1. Blackpowder

2. mortar or cannon

3. Pre 1899 technology

Although balck powder could be replaced with with any other heat source of a Pre 1899 technology.

Anybody know about a any steam guns or water cannons pre 1899?

[CrufflerSteve]

It seems like using the heat of the ignition could be a problem since it is such a short burst.

There might be other ways to experiment with water. How about pneumatic pressure? A large portion of the power of an old style BP cannon shot is lost due to the windage, since the projectile must be smaller than the bore for a muzzle loader.

If through some sort of gasketed sabot system all the gas pressure could be kept behind the projectile you'd get a lot more velocity. You'd have to use a lighter projectile since the water mass plus sabot would really build the pressure. Any experiments with this should be done with a berm between you the barrel.

Imagine cleaning your barrel while shooting it! (Sort of..)

Steve

[guardsgunner]

I know I've seen a pre civil war steam operated cannon in Sc. American on Cornell U. website. MOA. (very useful in fing artillery inventions) I will see if I can find it a post later.

[niju321]

Thanks for all the replies; I didn’t think about the legality angle. I looked on the Cornell site Guardsgunner mentioned and didn’t find anything so I suppose I’ll wait until he posts his findings.

In response to CrufflerSteve’s proposal I think the projectile we would use (probably a tennis ball or soda can) is going to have a reasonably tight fit, but I can see how most of the gas would leak by (especially considering that any projectile used is likely to be filled with cement or other dense material). I thought about that for a while and the only way I can think of to make a seal within my budget (the cheaper the better) would be to take a large number of rubber bands, then complete the seal by coating “gasket” and the inside of the barrel with some sort of thick lubricant like gear oil, basically making the projectile like a piston in a car engine. How would I keep the oil in this case from igniting? In cars the oil is not continuously burning, I’m sure, or else the fuel/air mixture would ignite as soon as it entered the cylinder. Also, how would I keep the rubber bands from melting in the barrel and making a terrible mess?
 
My testing facilities are not at all advanced; the shooting range for the first test will likely be an elementary school baseball field, meaning my “bunker” will probably be the walls of the school itself….

[John N]

I think it's a recipe for disaster. I'd be keeping that barrel clean and dry. Windage is a good thing. Your projectile should freely slide or roll into and out of the barrel. A rubber band covered projectile and oil coated barrel frankly scares the heck out of me.

[Cat Whisperer]

... There might be other ways to experiment with water. How about pneumatic pressure?  ...  

There were (Spanish American War -1898 - for example) a few ships we had that used pneumatic (perhaps steam) powered cannon - large ones.  It's been a few years since I've seen the pictures, but the bullets were a couple of feet in diameter.

[CrufflerSteve]

... There might be other ways to experiment with water. How about pneumatic pressure?  ...  

There were (Spanish American War -1898 - for example) a few ships we had that used pneumatic (perhaps steam) powered cannon - large ones.  It's been a few years since I've seen the pictures, but the bullets were a couple of feet in diameter.

I guess what I suggested is a piston type of device. If it could handle the pressure, a very small amount of powder could produce the velocity of a large charge. It wouldn't matter if it was water, oil or a metal piston, as long as it was noncompressible.

Ideas like that might have attracted interest in the late 19th century as artillery got more accurate & faster to get on target. The flash & smoke of artillery would be a clear sign to the counter-battery.

I think its a cool idea but I'll stay traditional. There is nothing like the roar and clouds of smoke from a BP cannon.

Steve

[Blaster]

.[quote="CrufflerSteve
I think its a cool idea but I'll stay traditional. There is nothing like the roar and clouds of smoke from a BP cannon.

Steve[/quote]

And Steve, don't forget the SMELL of burned blackpowder.
Sniff, sniff --- ahhhhhh! :wink:

[Cat Whisperer]

For what it's worth -

http://www.tecsoc.org/pubs/history/2002/dec13.htm

has more links to several 'dynomite' guns - powered by air.

[guardsgunner]

The steam driven gun I found worked like a centerfuge throwing balls out at a high rate of speed. tested.  1838.  
    Sorry. I'm not quite to crs but what I do remember is a little confused.