So I have heard old rumors of someone making a gun so effective that it scared the builder (safety concerns) and they destroyed the plans. This leads to the question of effective gas usage. 1. 1/8 tubing to bottom of T, brute force method 2. 1/16 to bottom of T, takeoff just below the magazine feed to feed the back of the magazine (shared gas) 3. 1/16 to bottom of T, dual ports on clippard with the second feeding the back of the elbow. There are many other configurations, but the basic test should be a straight mag to an o-ring and barrel. 150 PSI to that setup and you should have the optimum gun. If that setup blows through 10 soda cans, is this a danger or just folk-lore? What about two clippard valves, one to feed the T and magazine, and the second to the back of the elbow? Wouldn't this scenario give the BB at the o-ring the "punch"? Single lines to each gun so there is not shared gas feed? Multiple bottles? I also know, test, test, test. Would rather get some feedback from others first before I build 10+ guns to test.
I'm thnking that it is getting possible to have enough gas flow to keep accelerating the bb down the barrel after it pops through the o-ring. The cannons themselves, especially the Stalknaker interrupter design, are not the limiting factor for gas flow. Up until recently, gas flow was limtied by regulators and gas hose size. With ships moving towards larger diameter and/or multiple hoses, gas flow has increased the bb velocities, but stayed within the limitations of our safety equipment. A very recent trend since middle of last year is the use of two solenoids per cannon to open up that choke point in the gas system. Although I personally think it is overkill (one solenoid per cannons has consistantly given me 240 - 260 fps, IMO enough to travel through 4" of water and still make a below), to use two solenoids, I have to be curious what kind of fps a two solenoid system can do. Personally, I know of one person who has designed an efficient bb cannon that could exceed 300 fps. Although that sounds great, the cannon had a slow rate of fire that would have been a disadvantage in fast gun. My goal upon moving to 1/8" feed hose was to boost rate of fire without compromising fps. A well tweaked 1/16" hose fed cannons worked well to make holes but seemed to be to slow of rate of fire. The 1/8" hose fed cannons do not need the tight tweak and kept the rate of fire I wanted.
So a spurt gun setup should be the most efficient, as one just needs to pressurize the magazine. This would be the base line? Then it becomes an issue for rate of fire? Watching some of the guns at NATS this year, some were extremely high volume with a BB in there "somewhere". We were calling them "alien guns", you could hear their fire due to the volume expelled on each shot. Not efficient by any means (had high tank volumes).
I've witnessed and done testing with radar guns on lots of different styles of guns. The fasted tested was 270 fps, back in 07. I hear lots of how much faster my guns are than your guns, but when tested not that fast. This included a test on a guy (there have been a few) who claimed he had 300+ fps guns. Only 255 fps, but his regulator might have been low he thought. Maybe those 300 fps guns are done using a PSI over 150. When you get to NATS, gets tested and find out you're at 175 PSI, then get the PSI down to a legal level your super fast guns go back to normal. It's a good idea to have a test gage in the local group to check your stuff more than once per year. I have not tested every combo of gun yet. Could be something better out there. I took one of my guns that was at 250-260 with a single small Clipard hose and added a 2nd small hose. Same speed. I changed to a single large Clipard hose, lower speeds 240ish, oddly enough. I used two solenoids, one to the bottom cap with a large Clipard hose, one to the back of the breach with a small Clipard hose. Also 240ish.
I'm thinking that this might be overthinking it. The most efficient cannon I have seen was a negative pressure bb cannon built by Mark Jenks. Pretty sure he said that the cannon would get just over 100 shots from a 12 gram cartridge. That cannon is probably the most efficient to date anywhere. But it also had a slower rate of fire compared to our cannons. It is a balancing act between gas efficiency and fps. One has to go down to improve the other. Although I have wondered how much gas is wasted after the shot is fired and the bb has exited the barrel. While battling in Treaty with the 2 round per second rate of fire limit, I notice gas does not last as long probably due to holding the fire button down longer than needed to help time the 2 rounds per second. Usually I need to make a concious effort to tap the button instead of pressing it while battling in Treaty. In fast gun battles, the gas feels like it lasts longer, again probably because I have to tap quickly to get the fast rate of fire which limits how long the solenoid stays open. So what if there was a circuit that would automatically close the solenoid around 0.1 seconds after it opens? Would that save some gas?
Building a circuit to turn the solenoid off after 0.1 sec should be pretty easy. I imagine it could be added to the BC firing boards with just a little bit of software. I've got firing board design with variable delays coded in for Battlestations and Treaty. Although the software works on the breadboard I have not taken it to final form and tested with actual guns. Because one of the modes is continuous fire at 2 rounds/second, the software has to turn off the gas and it has a turn off time built in. I think I have it set more like 0.2 - 0.3 seconds right now, but testing could indicate that is too much. My concern is the on time will vary for each gun type and maybe each gun. So one gun might be fine with a 0.1 second on time, while another might need 0.12 seconds to reliably fire each time. Provisions could be made to change the on time, but it would require some more code and probably an additional component on the board (trim pot). I know the Treaty rules would allow the automatic timing, but would fast gun rules?
Fast gun does not allow automatic firing ... one round per push of the button only. Heh. Was thinking 0.1 seconds based on how quickly I can fire a cannon and still have it not misfire. To date, we've measured my best rate of fire at 11 rounds per second (0.09 seconds open solenoid dwell time). Even at that rps, the cannons didn't miss a beat which makes me think that 0.1 seconds of dwell could be enough time for the cannon to fire. Of course not everyone is that quick, nor may have high flow cannons, or may have tweaked the cannons very tight, so more dwell time could be built in to ensure no misfires. Mark, an adjustable dwell time would really make the board an all format, all purpose type of board that can be tweaked to fit all the various types and gas layouts of each ship/cannon type.
The boards that BC sells could easily be modified through software to close the solenoid after a set amount of time. (There could be provisions to adjust the amount of time needed through some sort of hardware interface but that is extra parts and $$) Like you mention not all guns have the same timing which makes standardizeing something like this pretty hard. Programming them to function as an "automatic cannon" or with ramping like the paintballers have would be rather trival as well. (again you would have to assume that all cannons only need the gass off for a set amount of time between shots.) I think it would be smart to put some sort of automatic fire/ROF rules into fast gun but I doubt that would stand a realistic chance of passing. (Something like an automatic system is allowed to fire up to 6-7? shots/sec, semiauto operation would still be unlimted ROF. I'm afraid of getting old and slowing down!) If you're wondering, the ROF control boards that BC sells limit the ROF with the "OFF" time between shots since it is impossible for the board to know when the shot was actually fired while the solnoid is in the "ON' state. It isnt perfect but probably still significantly more consistent than counting. (especially when the adrenalin is flowing)
Re: control boards A fast gun friendly approach would be to have your control board accept inputs and count the number of inputs received. The board would then send the same number of outputs to the firing solenoid, regulated by time as desired. This would be similar, but not quite the same as used in electronic paintball guns. A dwell time of 0.1 seconds would probably be sufficient for most cannons, but wouldn't work very well in overtweak or hang fires. I think I'll stick with Team Delta. About Lou's question - there are really many questions. If the rumor you heard is the one I've spread, there are no plans to destroy. There are prototypes ... out there. If your goal is "efficiency" in terms of minimum amount of gas for maximum effect, 1/16" hose is fine. The most efficient cannon design for gas consumption is one which does not pressurize the magazine when it fires. James Foster has such a design and it works well. Others would disagree based on his previous Nats performance. I think that it works fine, but ... it does not have that intimidating noise factor that we all love. If your goal is raw power, 1/8" hose and solenoids is your answer, ala Mr. Beckett. Your Iron Duke can't carry a big enough CO2 bottle for that. The associated reality is that due to diminishing returns, as Bob noted in his tests, you really won't get *that* much more velocity, you'll just waste that much more gas. You can only get so much acceleration out of a 5" barrel. Hope that's informative, Chris
Heya Chris, welcome to RC Naval Combat. Totally agree on getting best efficiency from using the 1/16" hose cannons. Even so, high flow design with an 1/8" hose is not too bad. Usually I get a full 50 round magazine from 1 oz of CO2. That is acceptable to me and enough to run the Verite PDN (three cannons) on a 3.5 oz bottle. The ID should be good with a 5 oz bottle (same as the Region 3 IDs). Now if someone was going to go dual solenoids ... yeah, may need a bit more CO2 capacity. Heh.
I really need to make a fast-gun event to see the hardware differences if nothing else, Oh hanging out with new battlers would be a plus too
Will have to do a few different setups to see what works best in my ship. Thanks for all in replying.
So Mike, if I send you a switch board with an adjustable on time, will you test a couple of different cannons and cannon setups and then post the results?
