Talk:The M.P.C.

Zerm: Just a few suggestions Nutz. '''Fixed this problem. New version posted!'''
 * Are you sure you meant "circumference" and not "diameter?" I'm pretty sure you did since 6" diameter fuckin barrel teh pwnz while a 6" circumference is kinda shitty (about 1.8" diameter which is smaller than a regulation potato cannon).  If you meant circumference anyway, might I reccomend you change your sorry excuse for a cannon to 6" in diameter or more.  You're a Knight of the Rumfish Damnit!

'''Ok, so we can definitely debate the length of the barrel. I agree that 10ft. is probably a bit long, but I will give you my reasoning.''' '''So it is certainly debatable. Now, I did just get a random picture of how the M.P.C. might look cool with a barrel the length of the Combustion + Secondary tanks. Cool yes, but Rumfishian badass? I think not. If the barrel was to be shortened at all, I dont think it should drop any lower then, say, 7ft.?'''
 * A 10ft. barrel seems freakin long to me. Considering the size of the projectiles, this is probably neccessary for any degree of accuracy.  However, you need to carfully consider the material which your casing is made of and also consider lubricating the barrel for reduced friction.
 * Especially with a 6in. diameter projectile, a longer barrel will be needed to ensure accuracy (as you said)
 * Would it look quite as cool if the barrel was shorter?!
 * Would THE RUMFISH like the idea of a short dinky barrel on such a badass cannon????

'''I believe that I may have found a fix to this problem. As you (Zerm) and I have spoken of already, High Density Polyurethane should be the ticket. In that case, I believe that 'this' could be where we should go. I only saw up to 5in. Diameter HDP, but we may be able to ask them to make larger if needed, or we could simply adjust for the slightly smaller size. Thoughts?'''
 * I am immediatly concerned with a combustion tank of that size. First of all, if you are firing water melons out of the cannon, that tank doesn't seem like it would cut it by an impressive margin.  However, a larger tank could be explosively dangerous.  Might I suggest either air compression with a valve or a multitank version of combustion.  By the multitank system, I mean one or two extra tanks of equivalent size that you don't actually fill with any combustable material.  By having the combustion in one tank with two auxillary tanks connect to it.  You will:
 * Not need a long tank which would be weak in the middle and prone to explosion.
 * Have extra oxygen to react more propellant.
 * Have more surface area on the inside of the combustion center to withstand pressure.
 * Be able to build greater overall pressure more safely.

All in all, a great idea still and, as you can probably tell, I would be eager to help or offer insight as best I can.

Also consider using high density polyurethane or polyethylene pipe for the combustion center. This high density plastic is shraptnel proof and much more resistant to heat and pressure. Its probably a tad more pricey but its quality and much safer for these specs. Besides, you shouldn't need to make the barrel out of the stuff. For reference, Techimo's 20 shot mortar rack uses high density polyurethane tubes for exactly the same reasons.

Response to Response
The 10ft. barrel is awsome and may be nesseccary for accuraccy. There will be no problems with it as long as its compensated for with extra pressure and friction reduction measures.


 * What measures do you think should be taken to reduce friction? Wouldnt any friction, especially between the projectile and the PVC be almost negligable? Depending on the material of the projectile, Im thinking so. Although, over a span of the 10ft. barrel, friction might come into play. Should we then lubricate the barrel in some way? Thoughts?

Also, good work on finding the HDP. 5" will be a sufficiect diameter since the barrel won't have to be made from it.


 * Maybe we can ask them to possibly make a larger HDP pipe for us? I should give them a call to see the lengths that they supply, as well as prices.

You want the barrel to be stiff and rigid so you may want it to be made of the stiffer PVC. Consider though that with the force we are generating, a 10ft. barrel is suceptible to breakage unless it is properly supported.


 * We can definitely support the barrel, that should not be a problem. We could line the barrel with something on the outside for added strength, or we could possibly take slightly larger segments of PVC (~8-10in. in length) and glue them onto the outside of the barrel. That might give us the added strength to prevent breakage. Thoughts?

Anyway, as long as you can interface the 5" di. tanks with the 6" di. barrel, then there are no problems.


 * Now this is something that I have yet to figure out how to do. Zerm, I would enjoy it if you would go with me to pick out the PVC and adapters when we get to building the MPC. I believe that  Nova might be of some good help and ideas as well, plus burgers always spark a creative mind! At that point is probably when we will find out how to interface the tanks with the barrel. At this moment, I dont have a clue how to do it!

If you are concerned about the size of the tanks, just make more tanks. As long as they flow into each other well, there shouldn't be any problems. However, what about the possibility of getting our hands on a metal pressure tank. You could get some serious power out of something like that.


 * If we were to build a metal pressure tank, then that would require the services of Nova's dad to teach us the art of welding. Also, if we were to go with a metal pressure tank, then why not completely convert the MPC to compressed air? That would make for an interesting project! Combustion is one thing, but compressed air is a new concept for us. Thoughts?

- Zerm


 * - Nutz