Hello all I plan on putting 3 of these on my VU. I purchased the parts, put it together in like 15 minutes, and test fired it. All I can say is Wow. I know the Kips do around 9 or 10 scfm at 150 psi, but I wanted a little more, you can never have enough right? So after reading Brian K's article on the MWC site using Clippard parts. I went thru the Clippard catalog and purchased some parts. I'm using only Clippard parts, nothing else. I'm able to get 35 to 36 scfm at 150 psi, and now I really like the guns. Can't wait till the Feb or Mar battle when the VU is done, maybe I will finally do some damage to Dons NC. Like enough to sink it, you see it has been battling for almost a year now, including at Nats, and has not been sunk yet. Here are some pictures of it.
so you like the mouse valves? I see that the setup will expose the mouse valve to the water if you sink, will that hurt it or dose it not matter? reason I ask is I was planning on using 12 of them on a manifold for the firing valves on my ship
I purchased the bottle which came with the valve, and regulator from. http://www.battlersconnection.com/ But you can get from also http://www.bderc.com/ Others have been using the mouse here in Florida and Georgia without problems. Nice thing is that they are around $15 new from Clippard. And the other 2 parts are $20, so for $35 you get somthing that blows away a Kips.
What is the compairison in weight and size to the KIPs? It looks like it is a lot bigger, might not fit in smaller ships. Looks like a lot more brass too. But pictures without a ruler it's hard to tell.
After a point more flow rate won't do you any good. Using a MJAV-2 is more flow rate than you can use. So you are wasting your time and money. Spend your time on target practice, it will do you more good.
Well what is that point, do you know? Also since its my time and money, and I'm willing to spend it is all that really matters, right? I don't mind trying different things, since I got most of the parts at the local recycle store for $2 or $3 dollars each, besides the actuator and poppet. The poppet, actuator, and mouse are 3 inches long. But it sounds like I'm wasting my time I'm told.
I've heard that high flow is good for firing multiple fast-gun cannons at the same time. One will fire before the others, causing the air to flow out that cannon more easily. The high flow helps the other cannons maintain pressure long enough to fire. This setup should help with double or triple sterns in a VU. Of course, thats just what I've heard, I have no actual experience with fast-gun cannons.
In general, a Kip solenoid will provide enough flow to fire a cannon as hard as required. The hardest you need to fire a cannon is so that a bb has enough power to penertrate at pretty much any angle after traveling about 10 inches under water. After 10 inches under water, even the most shallow down angled cannon will be below 1" and hitting hard area. A cannon down angled less than ~6 degrees will not pentrate the water surface, but will bounce or skip. If you can do ~230 fps on the bench you are in good shape. More bb velocity will simply not do anything. Also attempting to get high flow rates into cannons can have some negtive effects on relibilty. A higher gas flow rate, could result in not enough CO2 for a sortie. (depending on bottle size) Also high flow rate can hammer the piston and spring pretty good- depending on design. You might have piston or T deformation from the impact, or the spring may get squished. If you find you are lacking gun velocity, it is often more productive to look at the cannons. For instance, a small brurr from the cross pin being shot, can result in much reduced velocity, and loss of accurcy too. Barrel dents will have even more effect. If you don't have a cronygraph, the "coke can" test can be used. If you can shoot though both sides of a undented coke can, your velocity is rather well above 230fps. High flow guns can also create problems with the bottle regulator. In high rate of fire situations, the bottle or regulator might freaze resulting in loss of pressure to the cannon. I would not attempt to tweak the tripples as hard as the sidemounts. Most of the time stern guns only need go though a bow wave. And the harder you tweak tripples, the more tempermental they become about fireing at once. (probibly due to varations in bb size more than anthing else) It is normaly required to down tweak twin cannons somewhat, and tripples somewhat more.
I am a little confused. It looks like you are using a single MJV-2 valve (and MAT-2) to feed three cannons at once, with the mouse valve as the trigger. Is this correct? If so, tell me how it works. I've been thinking about doing something similar on future Age Of Sail projects, like the 74-gun HMS Bellerophon.
As you see it, it was just a test setup. Using one of the mouse valves fed by the Mar-1 regulator (0 - 100 psi), that you see attached to the left side of the mouse. The mouse is then attached to the single acting air pilot actuator (MPA-5), I used the larger version, because for the (MJV-2) it only requires 10 psi to open, while the smaller (MPA-3) needs 30 psi, which turns the mechanical poppet valve (MJV-2) into a air operated valve like the PAV-3 but with 3.5 times the volume of flow of the PAV-3. The large volume chamber on the far right is the high pressure input (150 psi) that feeds into the right side of the MJV-2 poppet. When the mouse is triggered, it opens the poppet with the CO2, and you get the high pressure out of the top of the MJV-2 poppet. I tried a much smaller volume tank, and saw no difference in operation. I tried it this evening with 1 gun, and it worked fine, tomorrow I plan on trying it on the Roma's tripples.
The nice thing about the clippard mouse valves is that they should supply enough flow to fire 3-4 cannons using actuators reliably. You can use the same setup for a variety of ships that way... Carl
I think you'll find that smaller volumes with higher pressures are more efficient, and also work faster. In all my MJV-2 cannons (Big Gun "Arizona"-type cannons) I used an MPA-3, and it worked just fine. I've seen photos of folks in the Queen's Own 1/72 scale club using MPA-7's on their MJV cannons and I just think what a waste. The clippard mouse valves are great for MPA 3's, MPA 5's, and MPA 7's. I once saw someone try to actuate three MPA 7's with a single SMAV (a positively microscopic mechanical valve) and there was a 2 second delay during which he had to hold down the trigger, in order to fire. Once he switched to a mouse valve, he could tap the trigger and they'd all take off. How does this setup do with rate of fire?
With the MPA-5 it fires as fast as I can press the button. I would rather use the MPA-3 since it is smaller and lighter, I just was not sure how fast it would fire.
A true statement and a good question. So lets figure it out, or at least take a stab at it. This is for a fast gun cannon, why? cause thats what I fight. First the point of increasing the flow rate is to make the bb see 150psi for its entire trip down the barrel. To do this you must input enough gas to make up for the volume being added to the system as the projectile moves down the tube. This happens at a varying rate since the projectile starts from a stop and moves to whatever the muzzle velocity is in the length of the barrel. So basically the worst case here would be just before muzzle exit when the bb has just achieved the final muzzle velocity but isn’t out of the muzzle yet, in one more instant it would be but for now pretend its not. Anyway it would be at that point that the rate of volume increase would be the greatest and the highest flow rate would be needed to keep up and keep the pressure on the projectile. We will start by making some assumptions about fast gun cannons to get to a reasonably close answer. Assume the barrel length is 5 inches and has an ID of 0.19 inches (this is the ID of a standard 0.25 inch copper pipe that is often used for barrels as well a magazines and other gun parts, for the tight tolerance stainless steel barrels this would be smaller and would lead to a lower flow rate needed so we shall use this as it will be more of a “worst” case) Since we are assuming a muzzle velocity of 230 fps as the max velocity needed for effective combat we will use that as the muzzle velocity. We want the rate at which the volume is increasing in time. The easiest way to get this is an area times a velocity, in our case the area of the barrel (0.0238in^2) and the velocity of the bb (165600 inches/min or 230ft/sec*12in/ft*60sec/min) which results in a volumetric flow rate of 3947 in^3/min or 2.28414 ft^3/min. But that’s in ACFM not SCFM so we need to convert it. Assume temperature is held constant throughout this process, its not but that just makes its more complex and all we want is a rough idea anyway. To convert from ACFM to SCFM is a little tricky cause you need to know the psia that the SCFM is for. From what I’ve read the conversion to use is: (psiaRating/psiaActual)*SCFM=ACFM So a valve rated at 25.5917 SCFM at 14.7 psia would give the required 2.28414 ACFM at 150 psig (164.7 psia) A valve rated at 3.2798 SCFM at 100 psig (114.7 psia) would also give the required 2.28414 ACFM at 150 psig (164.7 psia) These numbers are a rough estimate as to what should work, this doesn’t take into account flow losses and other things happening as gas flows from the valve to the breech so the actual values needed are probably a little bit higher. That and our guns aren’t perfect gas guns and never will be. Having a huge flow rate should let you increase your rate of fire but there are limits on that due to what the gun and control system and user can input as well as practical battling concerns, after all you probably don’t want to dump all your ammo in 30 seconds. Also it does let you pressurize the volume behind the bb faster which decreases the time between hitting the button and the bb leaving the muzzle. But effectively there is a limit to that too. I may have goofed something up in the calculations, fair warning. Yawn...time for bed.
I think the single biggest limiting factor in those cannons is the 1/16" ID gas line. Whenever I design a cannon for my Big Gun ships, I try to keep the cross-sectional area of the gas-flow paths the same throughout the cannon. So the cross-section of the ball valve equals the cross-section of all the barrels equals the cross-section of the distribution manifold. The MJV-2 valve (and MJV-3) both flow enough air to fire a 1/4" ball bearing at well over 160 FPS, using a MAT-2 and 5-6" of barrel (after the bend). I'd be willing to bet that you could fire at least two Fast Gun cannons from your setup, without any noticeable decrease in performance.
I'm using 1/8 in line feeding into the bottom of the gun, I only use the 1/16 for the magazine feed. Right now I keep them detuned during battle so that I do not damage peoples boats. I was going for a more reliable gun, this way they still fire hard, but at the same time I have not had any jamming. In my Nelson I was finding I was only shooting off about 1/2 the BB's, and the gun got jammed, it was like I had inconsistant CO2 flow. I'm just trying different things to see what works best.
There is a fundamental difference in how fast gun cannons operate and how big gun ones do... the fast gun cannons are (as we term them here) a high pressure, low flow cannon (although extra flow always helps) whereas the big gun cannons tend to be a lower pressure, high volumetric flowrate design. I've run quite a few fast gun multiple cannon setups, and the biggest trick with them is to prevent cross talk between the cannons. Cross talk is caused by one cannon firing before the other, dropping the others pressure enough to not fire reliably. I have dealt with that in only one way that truly worked every time. That was an independent accumulator tank for every cannon (or a large enough one for them all that one gun worth of co2 is negligable compared to the whole volume). I have tried running larger tubing to the classic fast gun cannons and have not noticed much difference (a little bit, but not much). Another thing that I have noticed is that too short a length of tube from the accumulator tank can adversely affect the firing. I suspect (but lack the instrumentation to prove) that the low pressure wave coming back from the first cannon that fires needs to be delayed before reaching the accumulation chamber in order that it not affect the other cannon that fires a split second later. This is a balancing act because longer tube means slower refire rates (along with larger accumulator) but more reliable operation to a point. (everything in moderation) My yamato, with tripple sterns was a great, reliable setup. I ran two large accumulator tanks, run off two separate CO2 tanks (allowing effectively twice the refill rate of a single tank) the outer two cannons were fired off of one accumulator tank, the inner cannon off the other. I tried running them all off one tank but was not happy with the fussyness. I switched to the aforementioned system and they ran perfectly. (this setup even works well in the canister style tirpitz cannons I made for fast gun last year, although they are a bit easier to tweak consistently as the compression seat is tied together via a cross bar) Keep up the experimenting, that is the only way we find out better ways to do things.
