P-700 Granit dimensions

[JWLaRue]

You should be able to get stainless steel tubes from places like McMaster-Carr.....

-Jeff

[Ralph --- SSBN 598]

Here's the link to their home page.
McMaster-Carr

[KevinMC]

Sub Driver has a gas system as well, but I can't figure out how you charge the tank, or what gases are used. I am interested in hearing more from Kevin about the recoil as that is an issue. I am using a water tight deck rather then a water tight tube so I have less space in the hull, but I have more room in the WTC.

The Sub Driver system are an evolution of the Dory torpedo design, and like Mike's system they're Propel powered. (But you've probably figured that out by now.)

It's not so much of a recoil issue as it is a delta-trim after launch that I'm thinking of. It doesn't take much mass change at the bow/stern to upset the fore/aft trim of a boat in submerged configuration, and a loaded missile/torpedo is definitely a mass which needs to be considered. When that missile leaves what fills in behind it? The direct answer of course is water, but what I'm leading to consider is how close in density are your missile and the water that will replace it. What effect will that mass change will have on the trim of your boat, both in fore/aft trim and total buoyancy? My missiles are slightly negatively buoyant so when their mass is replaced with water my boat gets just a little bit lighter. I've not noticed any fore/aft trim change after launch, something which I attribute to my launch tubes being pretty much on the CG.

As you've stated however the solution set I chose isn't a candidate for your boat. That's not a bad thing - and it affords you the opportunity to work in a different solution space and create a design that will be all your own. While you're working at it, however, you might want to consider developing in the following order:

1. Look at your missile design very carefully and try to come up with a solution that will ideally fit in the volume you have to work with. Build up some prototypes and check that you can get them to fly predictably. (I can't stress this enough - Trust me when I say that an errant missile shot can really mess with your day.) Test, test, test, and test some more. Start with land-based launches, then move to static underwater launches. If it doesn't work right, go back and change the missile design until you're happy with it and it works right. Gas propulsion or other, what you're making is a rocket and there are plenty of resources on the net that can help you to get it to fly right. (I had to add nose weight and a fourth fin to the "booster" section on my missiles to get them to fly right. Also note that you've not spent any time modifying your boat yet - better to develop a workable missile and then fit it to your boat then to spend a lot of time fitting an unworkable missile and then have a lot of re-work to do to make it right.)
2. Now consider how you'll get that missile and a launcher to fit in the available volume within your boat. If the launcher won't fit maybe you have to move things around in the boat or make the missile a little smaller to make more room for the launch mechanics. Either way, you're still installing a missile design that you know worked before you put it in the boat, so it will still work in the boat. By the way, did I mention test?
3. I suspect that a propel missile will be lighter than my "chemical" ones, suggesting to me that when they leave your bow may get heavier. See if you can mock something up to test this effect on your boat once you get it to the point where you can sail it. If it's significant, do you have the ability to add something to counteract the effects of a launched missile? (Sliding weight, dropable weight, or perhaps a secondary air bladder or piston at one end of the boat that you could use to re-trim?) Be prepared for this when you're installing your launcher, best case scenario is you don't need to do it, worst case is you have to follow through with what you planned.

There's lots to think about here - I hope I've added more wind to your sail than I took away, but the sooner you start thinking about the hard parts of this journey the faster you'll overcome them when you get there. It's a long road to travel, but it really is worth the effort.