Hi, Can I make a 1 1/2 unit spurt gun for the I-400? Looking through IRCWCC rules it says a 1 1/2 unit single shot gun is allowed, doesn't say about a spurt. Can't find MWC or Treaty build rules anymore, the old shortcuts I have are no longer valid, I've been away tooooo long! Second, since there is no gun on the forward casing, just the catapult, the plan was to have the muzzle sticking out of the front of the catapult. I don't know if that would be considered 'super structure' or not, but is it a structure about the deck Thanks, for any input, Jay
MWC rules totally allow it. In 2012 I had the honor of being the first ship shot by Frank Falango's I-400... He was running submerged near me, and I yelled 'How cool is that!? It really runs!', and then he surfaced... and I yelled 'OMG! It really surfaces! How cool is that!?' and then he shot me with his spurt gun, and I yelled 'OMGZZ!!! It actually shoots! How cool is that!!?!'. And we were both happy. So there you go. I believe that Frank mounted his inside the superstructure, facing forward. Totally awesome to see in action. A testimony to his build skills, I was happy to get holed by it
Very cool, Thanks Tugs. Is there a link to the MWC rule set, so I have a copy to refer to? Are there links to pics of Frank's boat? That would be cool to see. Thanks, Jay
Submarines are only 1 unit in MWC. That particular one is 1.5 units in IRCWCC, which, appears to allow having a 1.5 unit spurt (15+10bb for 25bb I think). But I'd ask on the IRC mailing list first if I were you. MWC Rules: http://www.mwci.org/rules.shtml IRCWCC Rules (out of date) : http://www.ircwcc.org/files/Forms/R...nHTML.html IRCWCC Mailing list: http://groups.yahoo.com/neo/groups/IRCWCC/info There are pics of franks boat in the pictures section that I took at 2012 MWC Nats. http://www.rcnavalcombat.com/Forum/tabid/58/aff/584/aft/442782/afv/topic/Default.aspx and even a video: http://www.youtube.com/watch?v=msPEG3bxnmo
I'd run a half-unit pump. You never know how diving stresses will change the fit of the balsa. True it presses IN, but if you've fit the balsa to a compound curve, it could gap a corner. Or, the pressure could crack a spot and push some seepage in.
Yeah, that rule needs fixed. They meant to ban using a ballast pump from also being used for damage control. Not to ban a regular DC pump from doing damage control.
Hi Jay, Spurt guns are allowed in the I-400, which is a 1.5 unit sub under IRCWCC rules. I built a self-draining spurt cannon for my first attempt at the I-400 using a BC hull I'd deepened. I proposed a completely new set of rules for sub construction that was posted here and on the IRCWCC forum years ago. It solved the problem of potential balsa hull implosion (which could easily occur in only a couple of feet of water), by making the upper hull, free flooding extremities of the lower hull and the ballast tanks penetrable. My I-400 had short free-flooding bow and stern sections on either end of the solid pressure hull. The hupper hull was cut out like a normal IRCWCC hull. The ballast tanks were amidships on either side of the hull and were penetrable. Penetration of either ballast tank would result in partial to full flooding of the tank depending on how high the hit was. There would be a severe list to that side, rendering the rudder useless. The opposite ballast tank would then be almost completed exposed and a penetration of that tank would ensure a sink. I think we discussed this when planning construction using the new I-400 hull. Your advice was to put the ballast tanks in bow and stern, which would free up a lot of space in the pressure hull, In that case penetration of either tank could cause the sub to stand on end with bow or stern exposed. Penetration of the exposed end would result in a sink.
Hi Bob, I remember those conversations and the ideas you had for construction of subs but I thought we were conversing more with the Treaty guys as opposed to IRCWCC. I have just been gone for so long from the forums that I can't find any of the rule sets that I had referred to before. I have finally got the garage, (which I had to have built first), to the point where I can start working on boats again. I am pooling the collective sub knowledge in the office and am hoping to begin some work on the I-400 in the New Year. The custom battery packs I had thought about were not too successful, charging became an issue unless I wanted to remove the batteries from the casing each time, although the new batteries that Strike has will solve that I think, as long as they can be hooked up in parallel and I can’t see why they couldn’t. The biggest issue I foresee for me personally is the cannon. I have never built one and although I have an idea for a 5 shot spurt gun in my head, that doesn’t mean it will work out. The idea of a self draining cannon is appealing, having a barrel full of water would lessen the hitting power of the cannon I think. Did you have any kind of valve to seal the drain hole when the cannon fired? I will pass on anything we figure out to you if you’ld like.
Bob, I remember seeing those rules a while back after being shown them by one of our local battlers who has your old I400. I am wondering how you came to the conclusion that the balsa would implode in only a few feet of water? Frank F. had one of the new I400 hulls at nats in NC last year and I don't recall him having any issues with imploding balsa despite having IIRC, a single ballast tank inside the sub.
That's where I put mine after seeing Frank's ballast tank. I think he went with thin (but reinforced) ribs, relatively close together, to support the balsa by avoiding long unsupported sections.
Balsa would probably be OK in a couple of feet of water but pressure differentials can be more significant than you would expect. When I worked as a diver I was told it was possible to get a pulmonary embolism by holding your breath at a depth of 4' and surfacing. One of my med school profs who worked with the fleet diving unit said that was possible. I wouldn't trust balsa sheeting to be reliable at a depth of 6' or more. Imagine a 6' tall column of water the same area as the sheeting panel between two ribs. That's quite a bit of weight.
I don't think that Frank dove his deeper than 2 feet, maximum. I certainly wouldn't trust balsa at 6 feet of depth, that's asking a lot from 1/32", like you say. I think it would be possible (the embolism in question), as the diver would be inhaling air at the pressure 4' down and then surfacing. I've been doing a bit of (decidedly non-technical) reading on underwater physiology work done as related to the SeaLab project. Fascinating stuff and braver men than I doing open-water diving. I liked to stay inside my sub where it was warm and relatively surface-pressure most of the time.
When we were talking about the construction of boats, Dave and myself did an experiment in my basement. Two pounds of lead weights, one square of balsa supported by what we figured was close to the size of the windows and a one square inch piece of wood. When we put them together, the result was a hole in the balsa. That equates to 4 feet of depth. As it turns out the window size was too big by about 1/2 inch in both length and width. Now I get that results will vary, the quality of the balsa is huge, the stuff we used may have been a couple years old and the weight didn't go crashing through, it took a bit of time. The sub will be moving and therefore the pressure will vary some too. This all being said, it doesn't really mean that at 4 ft down the balsa will cave in but it does put some doubt in place. I suppose I can sheet the Sri Ayuthia and put in into the pool next year, see what happens. That is the only real way to do a proper test. J
warm?! inside a sub? Maybe by the SSMGs... not up in the cone on TMOW (in the N. Atlantic). Average temp in my torp. room was 52-58F. I stood watch with long johns on underneath, wearing my boat coat, and a watch cap. brrr
LOL Mike, everywhere I stood watch we were reasonably toasty (or worse when the A/C got shut down for Rig for Reduced...) Even the Cone wasn't bad, I was battle stations port battery captain my last deployment, although admittedly that was in the Adriatic most of the time.
Jay, I don't think a bow spurt gun is practical because the bow rises too much to get the barrel at or below horizontal. The catapult is too small to accomodate a barrel let alone a standard Foster style beach. That's why my first I-400 had a stern gun. Spurt guns for the I-400 or a DD/Gunboat (i.e. Sri Ayuthia) are easy to make. Use a T-fitting with the barrel and breach at one end of the horizontal T and the magazine at the other. The mag should slope upwards at about 5-10 degrees.That ensures H2O will drain out of the barrel when the sub surfaces - worked fine on my I-400. If your spurt gun is to fire all BBs at once connect the breach directly to the mag. If you want a repeater put an interrupter pin in the lower arm of the T with the breach and mag installed horizontally above. The interrupter pin has to be tapered to a point, so it will drive upward into the line of BBs and those toward the breach will be fired, while the rest stay in the mag. To work well the BBs need to be alligned above the pin so where two touch is directly above the pin's point. By varying the length of the chamber between the center of the pin and the beach O-ring you can fire different numbers of BBs. I've built spurt guns that fire 3 BBs at a time, giving 5 shots with a 1.5 unit spurt gun, and 5 BBs at a time giving 3 shots with a 1.5 unit spurt gun. Test firing at 12" range with 3 BBs per shot produced ragged holes about 1/2" in diameter in 1/32" balsa. 5 BBs per shot made holes between 1/2" and 3/4" wide. Remember that I designed them to go in the bow or stern casemates of the CL Profintern and engage stationary battleships shooting at magnetic shore targets in IRCWCC Campaign. The ends of 5" long spurt gun barrels would be ~7" from both bow and stern. The spurt cannons were to be angled down to hit the water 12" from the end of the gun barrel, hopefully causing a large hole on or below the waterline of the battleship. The armamet should also be effective against convoy ship models but with the range increased to avoid hull to hull contact, which is forbidden.
Awesome, thanks Bob!! I will give that a go, we shall see what I come up with I can picture it in my head, so I am farther ahead than I was. J
I have a 1 unit spurt on y I 400 mounted in the hanger so I can reload with out takeing off the deck but I think u can split the 1 1/2 unit gun in to a full unit spurt and a 1/2 unit spurt 1boww and 1 stern I also tested it in a pool at the nc nats it was an old pool with wire mesh so I lost radio signal and it went to the bottom of the pool 8feet down when I opened up the deck not a drop of water inside ship worked perfect all week not realy effectef but did score some hits and had a great time leif goodson did score 3 hits on it but they were 2 on the deck rim and 1 just below the 3/8 deck rim but it was deep enough to just stick ond not go through RA RA,
