R/C Naval Combat

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Originally posted by Kotori87

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. :o

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For small gun you have to shoot just a hair over 250 fps to have the same energy that a 1/4" steel ball bearing has going 150 fps. But thats not very realistic since people don't tend to have their eyes at point blank range to an armed cannon (if you do it could be argued that you deserve to lose it, well that or the ability to procreate, or both). Anything the shot does to get to your eye will rob it of energy(bouncing off a deck,skipping off the water, potential energy, air resistance, etc) so by the time it gets to your glasses its lost some energy. Man in the water situations are where its most dangerous but thats why if someone goes in the water you make sure your guns aren't aimed in that direction. And you always unpin/pin your guns right at lakeside/on the water. If you follow the established safety rules there isn't a problem with current gun velocities and the safety glasses we use, least not on the small gun side of things. However I am curious what velocity is required to go through 2" of the blue foam with a small gun cannon, its still not realistic to test every gun before every battle but I am curious.

I would think testing of cannons would happen a couple times per year or if the cannon(s) are challenged. The test would be the same for everyone, if the guns fail you don't compete its should be that simple. I don't see the point of a ship suffering that much damage if it can be prevented.

We test the guns before the first battle of the event. If someone feels their guns have become hot later during the event they check them again. We use the honor system not only for the guns but the speeds. It is very refreshing to hear a captain state that he thinks his guns are firing a little too hard or that his ship seems to be running a little fast and they call to check their own ship.
I guess one of the things that gives us the time to check these things is that we don't count damage, plus with the rate of fire rule we don't patch as much damage. Less time in the pits and more time on the water, wow what a concept.
One other thing that we put in front of everything is, "SAFTEY". Treat every gun like it is loaded. The fun naturally follows. And for me, and I hope others, this is a hobby. I do it to have fun.
The 2 inch foam works for us. It's cheap and it's easy. Will it work for others? I don't know. Will it help in keeping someone from getting hurt? One can only hope.
Great thread.

It would be good if the person in question stepped up on there own, but it most likly will not happen. So that leaves a challenge, but if you don't have any foam at the lake, not much can be done.

Thanks again for the input. I've discussed this with several captains now and the concenus is to have a standardized testing method... either before season and /or for lakeside... to keep everyone "honest"... let's be real here... it should be a bunch of guys having fun out there.... right?

Chris, We challenge our own boats, and "It is good" to see it. It is really niece when people police themselves.

Getty... that translates into what I think would be the best outcome. Have an opening season checklist and then let the captains "police" themselves..... it would make life easier.

Do you guys only tweak your guns at the start of the season???

No buI also think that testing before any major event would be a good idea.

You have to consider this... our season lengths could be as long as four months to as little as two days up here. Why do you think we chat so much online? :)

True but something like this must be watched for no matter the length of the season.

Velocity.... not tweaking.... I can't think of any captain in the past three years that once their cannons worked they left them alone.

Tweaking changes your velocity, the more you tighten down the nut the harder the cannons shoot(the faster the shot goes). Tweak them to hard and your rate of fire goes down (really the response time from triggering the shot to it firing increase but that hurts your rate of fire), tweak them to had and your guns just wont fire(and you might find a leak or two in your system).

The velocity required to shoot through 1/32" balsa depends on:

1) Angle of impact.
2) Amount of water bb travels through.
3) How hard the balsa is.

With nice soft fresh balsa (no patches), at right angles, above the water line (no water), something like 130 fps will go though.

With 180 fps you can pretty much penterate at any angle above the waterline, with fresh balsa.

Hard balsa will require more velocity, but I have not tested that.

Shooting though water requires a lot of velocity. Guns with shallow down angle will require more velocity, as they must go though more water to reach a given deapth. A 6 degree down angle sidemount will need to go through about 10" of water to hit 1" below waterline.
If the angle of impact is bad, it will require something like ~220fps to make a hole, in a consistant fashion.

Things get worse with you consider shooting though bow waves and such, as even more velocity is required.

As a practical mater, the limit of 150 psi to the cannons, pretty much limits upper velicity to 240 fps.

These numbers are all for bbs and 1/32" balsa (Sig contest grade) with a layer of silkspan on each side- which will pass a 8" drop test.

Also:

The idea that lower velocity will result in a "safer" is a bit of a misconeption. BBs at the velocity we shoot at can dammage one thing on a person that maters, eyes. No mater what velocity you use to go though balsa, you will still dammage eyes. No way around it.
If the guns "sound bad" people will treat them with respect, and be carefull. It they sound "weak" people will be careless.
So hard shooting guns are less likly to cause injury to eyes.

Granted they hurt more when you shoot your foot. But that just reminds you to treat them with respect.

Note also, you _will not_ shoot through saftey glasses with RC warship bb cannons. I have tried with pellet rifles (with pointed pellets @625 fps), and they just will not go though.

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Originally posted by Chris Easterbrook

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.

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Thanks for the info.

Good points Snipe and Special! Appreciate the input and clarification..... some things here to wrap the noddle around.

If there is nothing further to add?

moving forward with suggestions..... thanks all.