Ok. Closed out silicone barrels and opened up what the real issue is. Velocity control. How do we test for it? I've heard Buddy's story about the guy with the Yamato that fired way to hard and was ripping fiberglass and SS apart. I've heard what you can do to make undetectable modifications to your bb's.... it's not pretty. I think that if we can figure out a way to standardize testing and make it more about what speed your bb's shoot out... it would be more benificial to the sport as a whole. Any thoughts or concerns? Perhaps you would like to share a story...
Chronograph would do it. My roommate at RMC had one for his airsoft guns to tweak them down a bit...and since we're both engineering nerds we ended up calculating the force they'd hit with and other such nerdy things. I think you can probably find one online that'd work quite well. If you guys like the chrono idea I can explain more on how it'd tell you exactly how much force the BB is impacting the target with. http://www.redwolfairsoft.com/redwolf/airsoft/Category?menu1=8 I would recommend either the 1st or 4th chronos shown on this page. Send me an email with your number Craig, I'm now in province!
Guys, there is no veloicty problem. Those that maintain there is, are telling fish stories. (undetectable modifications to bbs are BS) At 150 psi, bb cannons have enough power to shoot though water, and a hull skin. If you lower the velocity, you will shoot through less water, to still be able to go though a hull skin. If you _must_ have a lower veloicty, a lower pressure would be the best manner to do so. Else you will be checking every cannon every sortie of every battle. Given that cannons have a veloicty disturbition, that varies with the gun type and bb quality. You will have to do more than one measurement per gun. To make it practical, everyone would need a veloicity measurement device. And people whine about the cost of this hobby allready. So buy that chronograph, you will find things out. Then measure how much veloicity it takes to shoot though a hull skin 1" down. (it takes more than you think) But do not make changes until you know what you are talking about.
Is it I have spoken to two gun smith freinds of mine that said they could mods to guns that would be very difficult to detect. Unless you know what to look for or have some very good testing equipment yo would never know.
It's not worth getting into any of it. The deal is.... we should have a level playing field out there. People are worried about panels getting torn out... equipment being damaged... fiberglass gettin' shredded... that's not worth it to me. Unless the captain who doesn't want his boat stepped on.... run over.... blowed up.... then well.... everyone should fire with the same amount of "umph". I think that is fair. The current ruleset has no testing standard for these "eventualities", it may be high time that there was. Chris did you have some thoughts on how tests could be preformed? Anyone?
Modification to the _guns_ are easy to do. But you can only get so much out of a cannon. The velocity of a bb cannon is related the the pressure you put in. Minor modifications won't change that much. There really is no "magic" change to a cannon that will make it fire much harder. People have been trying for years. The upper limit on a bb cannon is about 240 fps to have any kind of realibilty in combat. You can achive more than that on the bench, but it is not possible on the water. For good shooting with shallow angle side mounts (~7 degrees down angle) you need about ~220 fps, to shoot though hull skin 1" down. The bb has to travel though alot of water before it hits the hull. So you have maybe 20 fps "extra" above what is required. But the bbs have a bell curve distrubition in their veloicity. So you tweek your gun to 230 +/- 10 fps (due to bb varation) and you will have enough power to shoot below, but not be tweeked so hard the guns will jam. The reported cases of some yammato shooting though 1/8" (or 1/4" the story varies) is pure bunk. To shoot though 1/8" aircraft grade 5 ply birtch, takes 1000fps. 625 fps will crack it, but won't go though. It is simply impossible to get that kind of velocity out of a bb cannon with 150 psi in. I have no doubt that many people have had their suppersturcure beat-up and some thin stuff shot though. And I have seen several fiberglass hull shot though. However, in the case of the hulls, the amount of glass in the impact location often apears to be lacking. If you guys want your suppersturcture not go get dented. Fine. Use lower velocities. But don't run around spreading rumors.
I'm not sure where you're coming from with this specialist. Check with Buddy. He will verify the "rumor" about the Yamato as he was the one who came forth with the info in the first place. A discussion was had on these forums about it as well... As far as 1/8" versus what we use in fast gun 1/32 balsa... there would be some difference. Me personally? My NC was damaged by a ship with questionable but rules-wise sound cannons. No one says anything but there is no need to fire harder than is needed to penetrate the balsa. In three encounters with said ship I had five ribs cracked. Not a good track record. In retrospect I should have stayed clear, but, was unaware there was anything to worry about until I reskinned my ship. So. It is out there. Mods beyond the rules exist. I'm not concerned for my ship or SS... shoot it up.... I hope to give as good as I get.... that's what this sport is all about. If someone does something on purpose... and for the simple reason of seeing more carnage on the water... I'm not interested in that. I'm sure there are others who would agree. Let's also think of safety here. We are firing live rounds. Anyways. Let's get back to figuring out a way to test for this.
I would agree with that all a canon has to do is punch threw 1\32 balsa not destroy superstructure or turrets, what if that hit a person on shore you really could hurt somebody
So according to Specialist's numbers you would be ok with cannons shooting at ~220 fps since thats whats needed to put a hole in 1/32" balsa an inch below water if your guns are at ~7 degrees? What velocity were the guns of this "super" yamato shooting at? Was it over 200fps, 250fps, 300 fps? And what are you building super structure out of that it is getting destroyed so badly?
Some superstructures are being made out of fiberglass, some made out of a high density plastic called sintra and others made of wood. There are other materials being used out there but up here they are the most common.
Ribs busting from BB impact does necessarily mean that the guns are firing to hard. A very thick fiberglass rib can shatter into chunks if it is just glass and no fiberglass matt backing. Some areas of a model are not consistently strong as other areas. The mid way point of a bow at the waterline is weakest there as it is difficult to get sufficent matt in that area. I seen small chunks shot off but not cause water to leak in. The rule of thumb is to back the ribs with a wood backing and resin it in place to provide strength and keep the rib from snapping. Worked on my Swampy Bismarck for a good 9 years of hard combat. My Yamato is much thicker glas but alos has a more layers of fiberglass mat lining the hull so it' ribs are very strong but the armored stringer is weak as there is hardly any backing there. There's a standard of measurement in place already and pressure does dictate mostly how hard a cannon will shoot a bb. If a muzzell has too tight a tolerance or the breech is too tight the build up of normal pressure can shoot the barrel clean away from the breech which I have seen happen a few times. If there is..was..an incident than there's been no word of issue since. If it was tried then maybe it no longer is. Superstructures will get damaged under normal pressure firing velocity anyway. My Bismarck...Swampy foam..Yamato...fiberglass, have been damaged repeatedly. Warspite has chips off the corners of it's tower and rear superstructures but it's made from glass with little matt backing. Voided areas or bubble areas inside the structures will crack or chip. Edges will always chip from a hit. Balsa will eithr eat the bbs or pass them through...lol. Not all hulls or superstructures ARE made TOTALLY invincible to bb impact. Repeated impacts on thick plastic will shatter after a while. I've seen a velocity radar gun once used. Works pretty good. I am sure it's been tested already on cannons..does anyone know what the average velocity of a bb coming out of a standard cannon is?
I hope you don't mind an outside opinion. I seem to recall that one of the Texas big gun guys has fought both big gun and fast gun. He reported that the fast gun cannons hurt more when hit, which suggests that they are more powerful. Big gun cannons are perfectly capable of putting holes in balsa that is four times as thick. Didn't the Treaty guys institute a foam penetration test using 1" foam, which is half the thickness used by big gun clubs? They are still able to sink ships just fine. Reducing power will reduce wear on hulls, and more importantly, improve safety. Why not limit the power of cannons?
Anecdotal evidence does not count. Measure and test, then decide. At MWC Nats last year we did some velocity testing of several types of guns. They ranged from ~200fps to 247fps at hard tweak. Not surprisingly, the hardest guns were home made. Bart Purvis did testing several years ago against extracted teeth. With his guns, you would need to be below 45psi to avoid shooting teeth in half. At that pressure, the guns could not be made reliable. Big Gun 1/4" cannon shoot much harder than our BB guns. The energy is more than double.
You know the ship damage is one thing. The thing I don't want to see is someone getting hurt. How many times have you had to tell someone at an event to put their saftey glasses on? Ships can be repaired. We've been testing with I think 2" blue foam. Thanks guys,
You're right,anecdotal evidence, especially when it's also hear-say, isn't good evidence. A 1/4" bb weighing 1 gram fired at the absolute maximum allowed velocity of 50m/s (about 164fps) has 12.5J of energy. A .177" bb weighing 0.4 gram fired at 75m/s (about 246fps) has 11.3J of energy. Fast gun balsa is 1/32" thick, big gun balsa gets up to 1/8" thick. Is there some reason you need to fire at almost the same energy when the armor is only a quarter as thick? Is it difficult to reduce the power of a cannon or would it require many people to replace their equipment? Is 200 fps sufficient to penetrate 1/32" balsa at 1" down? At first I was butting in without thinking much. Now I'm curious, because I don't understand why you don't want a limit on cannon power.
I agree the real issue should be safety, but who wants to repair damage that could be prevented by limiting the power of cannons, I would be courious how much pressure is needed to penatrait 1\32" balsa, then allow for a small increase over that and then put a upper limit in place. That will make the hobby safer and damage much more manageable.
Sitting back listening.... I can't really follow the math Sorry guys.... not my best subject in school. But, it seems that a 2" inch foam by gettysburg was mentioned. What were the results there? Everyone can weigh in on this the more info we have the better informed postition we can have. Thanks for the comments guys... keep em coming.
As I said earlier, we used 2" blue foam. If the bb's go through the guns are shooting too hard. We have no problem making holes in balsa. Above on and up to 1" below the water line. Our guns no longer damage super structure or fiberglass. As far as pressure, I think Mike Deskin had 110 lb springs for his regulator. Please don't quote me on that but, I am pretty sure he was using them. I think the reason the group I am in doesn't have a problem with D-tweaking is because for us, it is less about the competition and more about the ships, the history and having fun. Thanks for talking about this. My fear is someone getting hurt and it's side effects. What happes to our insurance, what happens to the ponds? It is hard to say what would happen but, I don't think much of it would be good. Thanks again, good topic, very interesting thoughts.
Hmmm... Safety... That brings up another interesting point. Most official "safety glasses" are rated "Z-87+". The test for receiving the Z-87+ rating is to shoot the glasses with a 1/4" ball bearing moving at exactly 150 FPS. Now, the safety glasses have to stop the projectile in order to pass, so they can *probably* stop a shot with more energy, but it's not guaranteed. If I remember correctly, the Big Gun velocity equivalent of 2" blue foam is 165 FPS. Doesn't that make you the least bit nervous, knowing that your cannons are firing with more energy than your safety glasses are rated for? And that's not even considering the possibility of multiple shots hitting at once.
True enough Carl I will be useing safty glasses for a consruction site. Is there any specific type of foam you guys use Gettysburg? I will pick some up when I find out what type of foam to use and start doing some tests, does anyone in halifax have a reg that can be adjusted? If so can I borrow it for the test?
