Recent shooting of the breeze at the build session...

Discussion in 'Big Gun Southeast' started by Tugboat, Jan 22, 2014.

  1. Tugboat

    Tugboat Facilitator RCWC Staff Admiral (Supporter)

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    For those who weren't present, we discussed The Rules. We decided that the WWCC rules set, lightly modified, would make an excellent basis for the BGSE rules. Changes that were mooted about:
    Get rid of the 3/16" cannon. Basis for this: It's a whopping .05" bigger in diameter than the easily available BB cannons. No good reason to have a separate gun size that's so close. We discussed the possibility of letting ships that under the WWCC rules rate a 3/16" cannon have a slightly higher rate of fire than the ships that use a BB cannon as the rules are, to represent the greater firepower of the larger guns. Not too much faster, though.
    Limiting pump power. The WWCC rules stipulate that battleships are limited to any number of pumps with two 1/4" outlets. The three of us agreed that this rule is based on old technology and that if left as-is would result in a bunch of non-sinking warships if they used modern pumps, given that currently available fast gun pumps are moving more than 2 gallons per minute through a 1/8" orifice. We wanted to make the standard easy to verify and test without taking ships apart or needing a special test rig. What we propose is limiting the actual power used by the pumps to a specific wattage, checked using a clamp-on ammeter, or an inline ammeter (or wattmeter, we can all do basic P=IE math, the end result is measuring the power). Any means of moving the water out of the boat is good, be if a centrifugal pump, positive displacement pump, magnetohydrodynamics, or an old-school chain pump. If someone wants to carry enough CO2 to run a gas-powered pump, I suppose we'll have to write a new rule.
    Those are the changes I remember. The optional 1/2" extra hull depth rule stands, but the extra depth is optional, not mandatory.
    Changes to the carrier rules were discussed, but as no one is running a carrier and we had boat work to do, it was not pursued at that meeting.
    Thoughts?
     
  2. NickMyers

    NickMyers Admin RCWC Staff

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    Obviously I am not part of the group, but I would comment on your pump restriction proposal. To me it seems to read as ' He who can spend the most money on power efficient design/parts and efficient flow, wins'.
     
  3. Anachronus

    Anachronus Well-Known Member

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    So would a trained ant bucket brigade be legal? :D
    ;P
     
  4. Tugboat

    Tugboat Facilitator RCWC Staff Admiral (Supporter)

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    I would agree, Nick, but we're limiting the pump power pretty severely... we're talking like 40 or 50W max per pump. Not a whole lot of advantage that an unobtainium pump can buy for you in that range. And given that I'll be selling the identical small pumps that I use myself for like $10 (no motor), I don't expect anyone to have a massive advantage (note: I will be refining the design of the small pumps for flow vs. power used, so anyone who cheaps out with one of my pumps will not be suffering any more than I am). At 50W per pump, that's less than $10 for the nicest brushless motor you can buy in the power range, most likely, running on a 10A ESC which again is less than $10. I fully agree that someone who spends time working on smooth flowpaths will eke out a slight advantage, but nothing insurmountable for other players to deal with. We'd be talking about fractions of liters per minute, at most.

    @J - it would be, but we'd find a way to measure the calories burned by the ants and convert it to watts...
     
  5. Anachronus

    Anachronus Well-Known Member

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    Or we could calculate the amount of work done over a given time couldn't we? It might be easier than counting calories. :)
     
  6. Beaver

    Beaver 2020 Rookie of the Year Admiral (Supporter)

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    If you could train ants to bucket brigade water out of a ship, I would come all the way down to LA to see it. :)

    Beaver
     
  7. AP

    AP Member

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    Was measuring flow rate too difficult?
    The reason I ask is because the idea behind displacement as a determiner of pump capacity was to simulate the larger damage control abilty of ships with heavier equipment and larger crews.
    As one earlier post suggests, there will be improvements to tech that will make some pumps better than others. If discharge rate is FIXED, the only benefit to a better pump is the savings in power - hardly a game changing advantage.
    Pumping water into a can is fairly easy as a test, unless someone doesn't want water in their hull....
     
  8. jstod

    jstod Well-Known Member

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    AP is right measuring amount discharged seems a bit easier. Also AP most pumps are removable so if someone is worried about water in their hull pull the pump out and test in tub of water :)
     
  9. mike5334

    mike5334 Well-Known Member

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    A better, faster flow rate test is the one developed by Bob H in the MWCI. Essentially, leave the pump in the ship. Pour water in the ship. Let the pump run until the water is pumped out. Shut the pump off. Pour 1 gallon of water inside the ship. Turn on the pump and time how long it takes to pump out that gallon of water. Flow rate can easily be figured with 60/number of seconds=gallons per minute.

    The beauty of this test is 1) pump stays in the ship, 2) accounts for any loss in efficiency in the pump system, and 3) is quick and easily repeatable.
     
  10. Gascan

    Gascan Active Member

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    We need to bear in mind two things: model warship combat is a competition, and therefore competitors must abide by rules to have a fair competition; and model warship combat is a hobby, and therefore must be fun for all participants. Big Gun Southeast is in that delicate formative stage where the rules have not been established. A few months ago I came up with a mission statement that I'd like to include, although I can't seem to find the text right now.

    My experience with big gun has entirely been with the WWCC, the first big gun club. Asides from the scale, there are three defining features that all big gun clubs share, in Texas, California, Australia and every big gun club I know of. The gun chart, the armor chart, and the speed chart are used to determine the arms, armor, and speed of every ship based off their historical statistics.

    There was a recent discussion in 1/96 Battlestations about simplifying the gun chart by eliminating calibers near in size to .177" bb and redrawing the divisions between cannon calibers to better represent the ships that were expected to be built. I think the standard big gun chart accurately represents the different ships that are commonly seen on the big gun battlefield, so that part may not be needed. Still, there is no effective difference between 3/16" and .177" that I have ever seen. I can think of only two reasons to keep 3/16" ball bearings: the big gun cannon chart is one of the three constants across every big gun club and other boaters may come visit with boats armed with that size cannon.

    The WWCC allows up to 1" extra depth added if the builder so desires. Most other clubs allow up to 3/8" extra depth added if the builder so desires. Because our models are semi-scale despite our best efforts and because we aren't using them to collect hydrodynamic data to perfectly recreate or scientifically study the naval battles of WW1 and WW2, I support allowing a small fudge factor. I'd rather see a bunch of semi-scale boats fighting than one or two museum masterpieces. If a builder must add depth to successfully build a model, he will also suffer the reduced maneuverability that comes with it. At least he built the boat he wanted and is now able to join the fun.

    Carriers are one of those interesting things that can add a bit of variety to the usual battleships on the pond. The problem is that we can't fly scale torpedo bombers off the flight deck and damage an opponents ship. I've seen them armed with 1/4" cannons based off their tonnage or the number of planes they carried. One could launch a dummy plane 3-6' to strike another ship and score a big chunk of points. Kotori suggested running them as cargo boats, to discourage them from getting too close to a battleship (just ask HMS Glorious what happens). The final conclusion was, as Tugboat said, to not make any decisions yet. It's not worth spending the brain power until someone actually wants to build a carrier.

    The biggest question on my mind is how to regulate pumps. The current WWCC rules (1, 2, or 3 x 1/4" dia. pump outlets based on tonnage) are very simple to check at the pond. The problem is that they work with older, weaker pumps. Most fast gunners put 50-100% more flow through an outlet half the diameter! Larger outlets would make ships with such pumps nearly unsinkable. Setting a flow limit will take care of most of the trouble, but is going to be really messy and troublesome to measure. That is the big reason why WWCC moved away from flow rates only a few years after being founded. A current or power limit would be easier to measure, but may still lead to variations in pumping capacity. I am open to hear all ideas for simple and effective methods of limiting or measuring pumping capacity.
     
  11. irnuke

    irnuke -->> C T D <<--

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    Hey guys...
    Big gun format isn't my cuppa, so take my 2cents for.....well, 2 cents.
    Anyhoo: My biggest beef w/ fast gun currently is the pump wars. The hobby was founded around the idea of shooting ships up and watching them sink purty. Super pumps mean less sinks. So what I'd suggest for your ruleset is a gpm limit / test as others have stated. "A 1 unit pump moves a maximum of x gpm. A 1/2 unit pump moves a maximum of y gpm."

    Good luck with this!!
     
  12. jstod

    jstod Well-Known Member

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    I think your best bet for the time being since you have so few members to start would be to keep the WWCC pump outlet rules but insist on using Strike or BC or Tug pumps with the same stock motors with no alterations to make them faster and limit the number of pumps to the same number of outlets. Simple fix to the rule problem without getting into complexities. both Strike and BC have their discharge amount listed if I am not mistaken.
     
  13. GregMcFadden

    GregMcFadden Facilitator RCWC Staff

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    On the pump topic. don't underestimate the impact of improved pump efficiency. If you limit current and orifice size to 50W and 1/4" respectively, a 100% efficient pump will move between 7.375 and 9.25 gallons per minute through a single orifice for 50W at 100% efficient. Given that the high pressure low flow fast gun pumps will be in the 5-15% efficient range give or take, and that commercial pumps at the much more realistic specific speed for that limit are available pushing 45% efficiency, I would not be surprised to see 50W pumps pushing> 5.5gpm out of a single 1/4" orifice or ~9gpm out of a pair of orifi. More still if the orifice is graceful and recovers a fraction of the pressure drop at the outlet. If you go to a half inch ID exit, the sky is the limit on pumping ability using only 50W. In the other limit (infinite area) one could consider, for a height change of 3", 50W gets you about 13gallons per second.

    If you do a power limit it will have to be in addition to the orifice limit to be meaningful. even then you would have to plan on seeing some significant increases as the pumps became more efficient
     
  14. Tugboat

    Tugboat Facilitator RCWC Staff Admiral (Supporter)

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    If everyone is okay with limiting pump flow rate, then I'm okay with that, we'd just have to pick a flowrate to limit ships to (adjusted for size, I'd suppose).

    Main thing I don't want: Pumps that flow so much you get no sinks. Easy testing would be nice.

    Oh, as far as the gun chart goes... I would say that we don't need the 3/16" size and think we should write our rules as we discussed, but if someone were to visit a battle with a ship that had 3/16" cannons mounted, I would be fine allowing them to use it as-is.
     
  15. Ace_Austin

    Ace_Austin Active Member

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    Extra depth in the hull: I'm onboard, for some small boats they need it to make them seaworthy/have enough room for systems.
    Pump capacity: Make it a flow rate. Easy, simple. Any number of pumps/locations/discharge sizes. Just all together they have to total up to XXX discharge rate for a ship size. I don't care if you are running a 15HP pump, a 2mA pump or a hampster with SCUBA gear to get the water out. ( Without the ability to propel the ship with the discharge of course) Add water to the hull, put a 1 gallon milk jug at the discharge and time how long it takes to fill it up. Apply some 4th grade math and BOOM. Pump is confirmed legal. Recertify once a year or upon challenge.
    Gun caliber: If you can build a 3/16th gun I say go for it. Larger guns had lower ROF, but more impact on the backside. You can always undergun a mount if it is easier for you. Turning up a ROF does add the capacity to do damage, but alters combat tactics in the wrong direction larger guns required. Battleships didn't get armed with 16" CIWS, so they shouldn't be trolling the pond sounding like it with high ROF guns.
     
  16. Tugboat

    Tugboat Facilitator RCWC Staff Admiral (Supporter)

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    The only ROF change that we discussed at all was for ships that previously mounted 3/16" cannons that went to BB cannons. Honestly, I'm willing to bet that with a loose tolerance barrel, a BB cannon could fire 3/16" ball bearings. Much cheaper to fire BBS from those cruisers, though. And for a .05" difference in diameter, I don't see a good reason for the expense of 3/16" ball bearings.

    The big guns would keep the ROF from the WWCC rules. No argument there.

    I'm okay with measuring capacity.
     
  17. AP

    AP Member

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    Flow rates are SIMPLE to measure, easy to understand, and in common use. If you are looking to standardize, it is a safe route. Many ships run that way and builders are happy to share how. I used cheap "jet boat" motors modded to run 30gph. All day. Every day.

    The closer you are to major club rules, the easier it is down the line.

    I agree, though, with the "reason" sentiment. It's a game. Needs to be fun. It's just that I honestly believe the rate-of-flow chart method is best and easiest. Once certified by a Tech Officer, there's not much reason to mess with it again. If outlets are standardized in your club, say at 1/4", all of you will KNOW ON SIGHT if a pump is too powerful. The streams themselves will tell the tale from meet to meet, and fancy measurements will never be required to see if that 30 foot stream of water really does work in a wattage environment.

    I think rate of flow lends itself to the best overall "historical", simple AND fun experience.