After starting to unintentionally hijack a different thread, I figured it was finally time for a thread of its own. Last night, I [somewhat] successfully tested a modified airsoft "Automatic Electric Gun" (AEG) gearbox-based cannon with a couple pieces of bb ammunition. The ROF was too fast, the batteries depleted too quickly, the gearbox cracked itself in multiple places, and I have a hole in the wall that I need to patch this weekend. The system fit within a volume equal to that of approximately four or five 12g CO2 cartridges. However, it was able to penetrate balsa at a decent distance (suggesting that I need a weaker drive spring). The test system I ran last night is driven by (I believe) a 220-size motor with some serious gear reduction (it's somewhere around 600:1). At the output, there is a pinion with teeth on only about 120 degrees of its circumference which engages a fiberglass-reinforced plastic rack of a length sufficient to facilitate compression of the spring, which is coaxial to the "bolt" that imparts the kinetic energy to the bb. I'm going to have to set up a bond graph/block diagram/transfer function (maybe I should have been a systems engineer) and then develop a CAD model for a design that performs accordingly, however the limiting factor remains the dependence upon batteries and whether or not there is any net reduction in overall weight. Even assuming that I would have the time to work on this in ernest besides all the other projects I've already decided to take on, it'd be some time before I could have anything ready that I would feel comfortable (or safe enough) to demonstrate or use. However, if this all works out as something more than a proof-of-concept, it'd be possible to use a solid state switch on one end of a radio channel and hold down the button while firing once every four seconds until ammunition runs out or batteries become depleted. This, of course, is an electro-mechanical system but the idea has casually been tossed around (sometimes tongue-in-cheek) of using an electromagnetic (coilgun) cannon system or even something to directly convert electrical energy into mechanical kinetic energy (railgun). While the lattermost is something I don't foresee anybody being able to successfully implement in our hobby for at least some time to come, what do you folks think of the other electric cannon concepts?
I'd definitely be interested in seeing if electric cannon technology can be developed further. If they could be made efficient, I think it would be a great boon to the hobby.
I haven't weighed what I built but I'd guess that it could be brought down to about the weight of a rock-the-boat regulator for a single barrel cannon. Ultimately weight is part of what I'd have to find out (in conjunction with how much added weight that enough batteries would be).
sounds interesting. I am not too concerned about rate of fire, as we could always control that out if need be. Take some pictures good experimenting -Greg
has this come any farther?... I dabbled a little bit in Airsoft .. and through looking at all the aftermarket parts for AEG's I had often considered adapting to RC naval combat... but they would have to be really really really downstepped on power.. but upstepped in strentgh of the firing gearbox to accomidate the firing of a bigger heavier projectile a good gearbox and motor combo with a large oversized piston could power 3 or 4 barrels ... ROF can be altered with gearing and voltage when I was playing Airsoft ... a typical AEG could run an entire day on a 1700ish MAH 7.2V battery pack... I'm sure a 4200MAH 7.2 could keep a BIg gun Cruiser or smaller in a few battles... only requiring the BB's reloaded a fast gun boat would probably require a Battery change each battle I would also bet that even with a 7.2 pack added, an elec setup would weigh less then a full CO2 system.. add in brushless and Lipo combonations and you could very much drop some weight ... hell even outfitting a reliable 1/144 PT boat would be possible... but not exactly cheap AEG parts are also WAY easier to come across then relying on a few people that can make good CO2 cannons...
Ever since I found this hobby again this thought popped in my head from my Airsoft days.. Have any fast gun clubs been denied access to a pond due to the "concern" for ammunition used? ie. the metal bb's. I know that they aren't lead but they do stick around. The airsoft bb's are 6mm if I recall right which is about .22 compared to the .177. But you can get "bio degradeable" airsoft pellets which means they will degrade when around weather. I know if they get wet they are still shootable in an AEG it is being exposed to water for weeks on end is what makes them go to powder. If this hasn't not ever been an issue well it is moot. Now this is not using AEG technology it is using their pellets. I know for a fact they at 350+ fps can go through the bottom of a pop can so balsa should be no issue even at lower fps.. just not sure at our fps. The other is their hop up system a type of system which would put a back spin on the pellet thus giving it greater range. But it seems for my limited seeing of battles online (read no personal experience) that most encounters are close and personal. Plus the hop up system has greater impact on increasing range as you increase the fps the pellets go. Does anyone know what the FPS of most Fast Gun set ups? Since we determine charge based on psi of hte CO2 it would be more difficult to ascertain that. A simple chrono rectifies that issue mind you, but I would think that the fps of our rigs may have issues registering on a chrono.
I once weighed some plastic and aluminum airsoft ammo and some 1/4" steel balls used in big gun (just a hair over 6mm), and found that the airsoft was much lighter than the regular steel. IIRC, it was 1/10 of the steel. This means that while it will work just fine above water, it will lose energy quickly and have less ability to score holes below the water line. I am not aware that my club has had any pond troubles due to the ammunition we shoot. The few issues we've had have been with shooting in the first place, not so much with what we shoot.
Say What? Steel isn't biodegradable. Sure it corrodes and becomes one with the pond muck but they aren't biodegradable.
I haven't so much as touched this path of development since that brief bout of experimentation with it last year. The main hinderance I can foresee with developing a usable electromechanical (as opposed to electropneumatic/pneumatic) cannon system is in devising a system in a way that functions with a sufficiently consistently low power consumption while being sufficiently durable for the operational environment and using enough off-the-shelf parts and sufficiently loose tolerences to not limit manufacturability to only a handful of individuals. Right now, finishing a ship and arming it (relatively conventionally) is my current priority over any more-involved hands-on development work (although I do hope to have time to spare to work on adding to the plans library soon).
