So many good idea in this thread - I'm going to try to provide add some thoughts across the different aspects for consideration: Armor: I think it would be fun to have variations in armor thickness that were more or less consistent with the way the ships of the period were constructed but simplified to a standard range of thickness similar to some of the discussion on the size of projectiles - so for example thickness 'A' for armor that was 8" or greater, thickness 'B' for armor less than 8" down to 4", and thickness 'C' for armor under 4" down to 2". This limited spectrum could also be applied in a way to simulate the taper that some armor belts had. It would also be good if we could correspond the performance of the guns to the ability to penetrate armor. So for instance guns that are in the large caliber group (12" and up range) could penetrate armor in the 'A' thickness (8" or thicker armor) guns that are in the medium caliber group (less than 12" down to 8") would have difficulty penetrating the same level of armor, etc. As for references to where and what armor thickness ships had I think one of the typical sources from the period (i.e. Janes Fighting ships) could be used reliably.
Love that idea. It would require a fair bit of engineering and prototyping to get a standard of what size cannon can do what. Of course at the 1/72 scale one could easily incorporate the AEG (automatic electric gun) mechanisms of a cheap airsoft gun. And by cheap, we are talking $30ish bucks, or about the same price as just the gun assembly of a fast gun without the solenoids. Plus having the firing switches and all of the electronics. Having a cheap manual spring one of those myself, I know they can put a lightweight 7mm plastic bb through ¼” balsa. They ARE designed to fire accurately over a distance so in close as PDN’s were designed it wouldnt be an issue. It would just be a matter of barrel sizing to the appropriate ammo.
yeah me and another guy were talking about trying to use an AEG design on fastgun boats. ended up stumbling on another design using an accelerator motor that may work too. but I think the electric accelerator motor design would be better suited to large/medium caliber main guns on cruisers and BBs because of the power draw of the accelerator motors. the idea being that you'd have a 30 second or whatever reload period, then turn on your accelerators and fire off another salvo, then shut them down for another 30 secs. like a pitching wheel for baseball. similar concept. and it'd be scalable for larger calibers, wouldn't have to carry gas, and wouldn't have to worry about the complexity of a pneumatic system.
Well that's interesting indeed, I've looked at airsoft mechanisms but not sure how small they can go - what ever we come up with I'll be happy so long as I can pull that 'death blossom' maneuver mentioned between two ships! I wonder if an air-soft mechanism could be adapted to for different pressures (smaller/larger orifices) or maybe a relief hole in the tubing to a gun that would blead off some of the pressure. Could multiple an airsoft mechanism be located in a ship and serve pressurized air via flexible tubes? On a completely separate topic - over the weekend I was thinking about how debilitating damage to the funnels was during the pre-dreadnaught period - burning coal in the fireboxs of the boilers was largely aided by natural draft—there being no or weak forced draft. The taller the funnel or smokestack, the greater the draft and hence the more efficient the combustion of the fuel. Start putting holes in the stacks and draft and efficiency goes way down. For instance the Russian ship Tsesarevich had it's funnels damaged during the battle of the yellow sea - and the damaged funnels greatly increased her coal consumption and reduced her speed to from 16kts to only 6 knots.
So I did all of the physical calculations to make an AEG for a fastgun cannon and it's.... debilitating. you need a chamber of about 100 cubic cm to get the pressure spike you'd need to make a foster breach gun work. it's about 1.5 inches in diameter by four inches long. plus the driver motor, the gears, the huge, powerful spring, etc. I'm sure you could do it with a completely different design, but arming foster breech secondaries with an AEG module powering a fastgun is a huge volume hog. the Boats I would want to build are approximately the same size as my fastgun boats, and when I was doing a sanity check the other day, the only way to make the secondaries work is with CO2 right now. If you try it, start from scratch and I would suggest basing any AEG design on an airsoft pistol mechanism. those are compact and reliable. The Main guns though, that's where I would experiment. ton of size and room to explore. Electric wheel accelerators can be super compact, velocity-adjusted, and you can shut them off to conserve power when not firing, which would also be a good reload time regulator
So what about having 1 AEG to deliver air to the secondary's on one side of the ship utilizing a multi-port valve - every actuation of the AEG rotates the multi-port valve to the next position (similar to how the cylinder in a revolver rotates)? That would still leave some work to do on the loading of the projectile but maybe there's an easy-ish solution for that? Instead of having multiple AEG's to trigger the Arduino could trigger one of those 9gm servos to effective 'open' a breach letting a round in and return to normal position 'closing the breach" prior to firing the AEG ? Could someone recommend an AEG pistol that I could buy to take apart for experimentation?
Assuming it's possible remote mount the AEG's and deliver air to the guns via tubing - I did some mock-ups: first one is the USS Monterrey (BM6) (~1090mm in length at 1/72 scale) it has a shallow hull but looks like it would be wide enough to accommodate at least 3 AEG's (no motors for the AEG's but I tried to allow for how big I think they would be. The second pic is of the the USS New York (ACR-2) which is ~1600mm in length and very deep hull - 9 AEG's would not be a problem - pretty sure I could fit in 12 - 15! There are some open source AEG gearbox components and looking at the position of the gears, I feel pretty comfortable saying that the orientation of the motor could be rotated to be more lined up with the air chamber (so longer but overall more efficient to mount close together and less wasted space). Perhaps there's an opportunity to design an AEG gearbox that off the shelf spare part components could be dropped in making the total assembly cheaper overall.
I'm going to elaborate a bit on my last, to make sure my reasoning is clear: big equation you're going to need to use is P1V1=P2V2 in order for your projectiles to launch, it will need to have a certain critical air pressure. That air pressure is approximately 12 atmospheres for a foster breech gun, your P1. So that means that you will have to measure the volume of your gun, and ALL of your hose lines (mine was 8 cubic cm). that is your V2. (8cc)(12atm)=(1atm)(V1). solve for V1. that is the size of your required cylinder. this volume will also have to include all of your hose lines if you do a master cylinder. Another compounding factor--the more exit ports you have on that single large AEG, the more critical the timing will be. this is very similar to why the wires on the explosive plates that detonate nuclear weapons have to be the exact same length from the power source. they all have to fire at exactly the same time. tweaking the guns would be *PAINFUL* which is why I suggest you either run with a modified aeg pistol system, and not a module to a conventional fastgun cannon. it will have a far smaller chamber volume and be more compact. and also why I suggest you not consider a master/bussed system-- it has all of the disadvantages of CO2, but with worse performance and troubles. If you need an example, get an aquarium air pump and connect it to a splitter and have it feed different air stones at different depths. So with those AEG pistol cores you have in there, I'm assuming you're going to mount them in the casemates. that's *about* how much room fastguns take up in a hull, so that's not a bad start. no tank, but batteries. that part's gonna be cool. If you're going to go the AEG route, try to use as much of the system in situ as possible. it may seem like a pain to do so, but the math is not in your favor because every extra bit of volume represented by hoses will reduce your velocity significantly.
and again, the accelerator wheel system does not require compressed anything, and just has two motors, one to accelerate the bb, and the other to feed it from the hopper
Anvil, thank you for the information and explanation - I think it would be interesting to do some tests on different possible armor material and the minimum pressure required to perforate.
AEGs are an interesting possibility. There are both benefits and obstacles. The two biggest benefit is the lack of CO2. The biggest obstacle is that AEGs aren't intended for small-caliber steel projectiles like bbs. They usually shoot 6mm plastic projectiles, with a relatively high surface area and low mass. Thus it is easy to accelerate to very high velocities with a simple spring-driven piston. I would be very curious how well the same setup would work using either .177" bbs or 1/4" balls.
You're right in that Kotori, but don't expect things to go smoothly with AEG unless you minimize the V2. Whomever wants to make it work will face serious challenges. Now, interesting point you bring up, but with a twist: delete the cylinder and just have that piston directly hit the BB to propel it? That may work. similar mechanism to the AEG re: skip gears etc. The Air of an AEG is just there to transmit work (velocity) to the object (BB). so that compressed air is just an inefficient middleman. Delete that middleman and I think you could do something really cool there!
Oh hey btw, if ya didn't already know, you can do the penetration tests without building guns. you can take a rod of the same diameter, round off the striking end (to duplicate a ball round), and drop test like in fastgun. your relevant equations would be using a set distance. Gravity being Gravity, you can get the same kinetic energy. However, Momentum, which is more appropriate for penetration, may not be 100% accurate because the equation is more mass-dependent. (Kinetic Energy, joules)= [(Mass, kg)*(Velocity, m/s)^2]/2 (Momentum, kg*m/s)=(Mass, kg)*(Velocity, m/s) All you have to do is crank out the KE of your projectile. Say for a 1/4" BB, you have a 10 gram round(this is a guess), moving at 45.72 meters per second (approx 150 fps) that yields like 10.45 joules of Kinetic energy. I would just get a rounded-end brass rod of the same diameter, and adjust the equation (your drop height) to reflect the kinetic energy of the 1/4" BB.
Yes, mass and surface area is a problem and I think using sabot's probably isn't practical =) what I would like to figure out is range and ability to penetrate different types of skin, particularly various thicknesses of aluminum foil. Low power might be less of a problem against essentially weaker armor. Lower power might also stop my wife from saying "you're gonna shoot your eye out"! I'm interested in exploring some alternative setups instead of the typical balsa for fun McMaster does have fairly light hollow aluminum balls in various sizes except.....they float...and they are corrosion resistant, .....and shiney....
Hell I don’t mind being a guinea pig and buying a cheap AEG to test with. Ive got 4’ of tight bore steel tube to play with too.
Dark, go for it, I've got one of those cheap pistols on the way too - but have been looking the larger components for rifles - and maybe increasing V1 will help compensate for a V2 that's not ideal.
when you guys do think of designing a system to use that AEG pistol mechanism, take a look at how the airsoft ARs feed from the mag. you could easily pull that off and index it using a pololu geared motor. So, on the topic of armaments, looking at the ships of that era, I think Torpedoes might be worth a discussion as a close-quarters tool, especially for the ships that had bow-mounted tubes that were above the water. 1/4" or 3/8" BB maybe? It'd be not-hard to rig a pressure plate with a spring-loaded piston that could just shoot out at a balsa-smashing-but-not-dangerous-on-the-bench velocity. And with Armor types, Whomever brought up the difference between Mild steel, Nickel Steel, Harvey, and Krupp cemented, there is a Formula for the difference between them! so you can pretty readily build a chart for the different armor types and thicknesses to accomplish a sort of parity. The big question then would be for ships like the Jalopy Battlecruisers, where they had a super-compartmentalized hull with a sloped deck armor or something else weird to protect their vitals. and yes, I woke up for some weird reason at 3:30 in the morning. Figured since I'm up, I might as well do something productive like looking up armors and such.
