Staged combustion chambers.

[inonickname]

I'm currently looking into how much muzzle velocity I can obtain from a 1x combustion launcher. Fuel will be hydrogen-oxygen or perhaps methane-oxygen. I am considering a new design to keep combustion pressures (and more importantly, temperature) up during the entire transition through the barrel by using staged combustion chambers, inspired by the V-3 cannon.

link

The gun used multiple propelling charges placed along the barrel's length and timed to fire as soon as the projectile passed them by, to provide an additional boost.

My idea is to use multiple smaller combustion chambers which run co-axial to the barrel with multiple high surface area ports. Each of these combustion chambers would be fueled with a stoichometric mixture of oxygen-hydrogen or oxygen-methane. As the projectile passes, the combustion gasses ignite the fresh fuel in each chamber and provides more pressure (throughout the barrel) and higher temperature. Assuming there is no projectile blow-by (and with the ammunition I'm using, there wouldn't be) there would be no issue with timing. Some of the gas from each combustion chamber may be lost but I wouldn't be concerned given the large flammability range of hydrogen.

Any thoughts? Before I'm told this isn't practical, I know. It's research, and an experimental launcher.

Tl;dr: using staged combustion chambers for moar pressure and temperature throughout the length of the barrel.

[psycix]

Might work, but I dont think there will be a lot of improvement vs one large chamber.

[theBOOM]

Hm I'm not clear on what your trying to do here....
You basically want to make a combustion based spudgun that uses multiple chambers which are connected leading to a barrel?

This is the sentence that has me stomped: "As the projectile passes, the combustion gasses ignite the fresh fuel in each chamber and provides more pressure (throughout the barrel) and higher temperature."

Also what size are you planning to be building this in?

[inonickname]

As a projectile passes through the barrel, the gasses lose temperature (and thus velocity) and pressure (velocity again). The idea is to use co-axial chambers placed throughout the barrel to be ignited by the gasses from the first combustion chamber and keep pressures and temperatures higher.

In 5.5-6.5mm (q-tip).

I can probably achieve similar performance with a low mix hybrid though.

[jmadden91]

I don't know if this will be a problem or not, but could the gasses from the coaxial chambers interfere with the motion of the projectile? Perhaps causing it to strike the edge of one of the ports as it travels?

[jackssmirkingrevenge]

It's been suggested before. I stand by the comments made in the previous thread, but don't let that stop you try and prove me wrong

[jimmy101]

Like Jack said, doesn't seem likely to work but if you think you can solve the various problems then go for it.

How will you seal the secondary chambers from the barrel to keep the fuel mix from leaking out the barrel? How do they get unsealed when the projectile passes?

[Hubb]

Have you considered a ram accelerator?
http://www.tbfg.org/papers/Ram%20Accele ... ISDC07.pdf

That's basically what you are trying to do. I have been researching these types of launchers for over a year now, but never have had any desire to build one (I was tempted when the competition came out, but didn't).

The biggest problem I foresee with the V3 design or a ram accelerator is the same the JSR explained. It looks good on paper, but is probably a lot harder to put together.

Now, with that said, since I've taken an interest in this type of launcher, I will put faith in you and hope you can get it done. I would really like to see a fully functioning version of it. Oh, and if I can provide any assistance to you (maybe some of my diagrams I've sketched up for the ram accelerator) just let me know.

Good luck.

[Technician1002]

Have you considered a ram accelerator?
http://www.tbfg.org/papers/Ram%20Accele ... ISDC07.pdf

Good luck.

Wow. Nice read. Noticed that one is for a 2,000 kilo projectile just under a meter in diameter. I noticed the sonic boom is projected to be above the threshold of pain out about 10 KM. Ouch.

Makes me think of the WWII supergun the V3.

[ramses]

I am inspired by that paper, and I may research it further. If you entered that in the contest, you would have had my vote.

[theBOOM]

Wow seems like a very interesting design... the only 2 complications I can think that will arouse from this are.
1. It's goanna be hard to time how long it takes for the fuel to ignite and also how long the projectile takes to cross the 2nd chamber / or the 3rd. mainly because if the 2nd or 3rd chamber ignite before the projectile has passed it would act as a "stopper" ..
2. It would be hard to figure out how much time apart you should set up your ignition system to.

[inonickname]

1. It's goanna be hard to time how long it takes for the fuel to ignite and also how long the projectile takes to cross the 2nd chamber / or the 3rd. mainly because if the 2nd or 3rd chamber ignite before the projectile has passed it would act as a "stopper" ..
2. It would be hard to figure out how much time apart you should set up your ignition system to.

Not really a problem as the chambers are ignited by the heated gasses behind the projectile. Just that care must be taken that the flame front can't outrun the projectile. (hydrogen flame fronts average around 250 m/s).

How will you seal the secondary chambers from the barrel to keep the fuel mix from leaking out the barrel? How do they get unsealed when the projectile passes?

Small lightweight "burst film" could be used.

Perhaps causing it to strike the edge of one of the ports as it travels?

Silencers in spudguns are regularly constructed in a similar manner with little issue.


Unfortunately it's riddled with problems. A low mix hybrid will offer more reliability, power with less service. I still have the 1km/s plans, but have been unable to find suitable materials..yet. It may yet be down scaled again to a smaller bore.

[jagerbond]

Thought about building something like this with our original twin O-ring designed UHMW rounds... So the pilot could be a simple spray and pray. worse case scenario the sudden increase in pressure could extinguished the combustion and it would a pneumatic with a combustion operated pilot...

[jmadden91]

Perhaps causing it to strike the edge of one of the ports as it travels?

Silencers in spudguns are regularly constructed in a similar manner with little issue.

In a silencer the forces are moving away from the projectile, into the silencer's chamber. Whereas in your design the force is coming in from coaxial chambers which could potentially knock the projectile off center?

**Note I have no experience in the matter and am talking out of my arse here haha

[inonickname]

The idea is that the projectile has already passed before the gas can pass in front/disturb it's motion.

Anyone have ideas on the most reliable/powerful gas injection in terms of spudguns? I have NC and BP but would rather keep it "spudgun legal". This is to drive a piston.. I'm looking at high pressure hydrogen, 20x oxy-hydrogen hybrid or something else..not sure.