I was wondering why you don't use compressed air instead of co2.I was wondering that because with air you could pump it up when ever with 2000-3000 psi and a regulater you would think that you can get more shots.
The Co2 bottles are at high pressure also, and we use a regulator to get the pressure down to around 140-150psi so that the 3000 psi CO2 doesn't blow up the plastic gas lines
It is pretty much a support issue. Unlike paintball, model warship combat does not have companies willing to pay for HPA compressors. The cost of a compressor usually is higher than an individual is willing to pay. That leaves scuba tanks as the lowest cost means to refill an hpa bottle. Doable, but somewhat of a hassle at a pond especially when the tank runs low and everyone else is using easily available CO2. Pound for pound, liquid CO2 has more energy than hpa. To get the same number of shots as CO2, the HPA tank is usually larger or requires a higher pressure. That eliminates hpa for many of the medium and small ships due to space limitations. HPA offers advantages over CO2 such as a constant pressure no matter the outside air temperature. HPA will not freeze a bottle if a lot of air is used. Even those advantages are not enough to offset the disadvantages of hpa over co2.
It's not just a matter of support. HPA bottles actually store much less usable propellant than their equivalent CO2 bottles. Paintballers prefer HPA because it is less likely to freeze their regulators during rapid fire. Our ships can avoid that problem simply with a properly installed anti-siphon tube. This allows us to benefit from the greater propellant storage of CO2. For comparison, I ran my Viribus Unitis (Big Gun) on both HPA and CO2. The 48cu.in. HPA bottle was good for ~15 to 20 minutes of fighting, roughly 1000 rounds of ammo, from a good fill. My 20oz CO2 bottle was good for twice that, and still had a couple oz of CO2 left over to bleed and cool the bottle to ensure a good next fill. The same concept applies to the fill tanks, too, but even more pronounced. A properly installed CO2 tank will fill bottles with good liquid CO2 until it is completely empty. A Scuba tank fill station will only top off the first bottle it is used to fill, then its pressure drops slightly. Every fill after that reduces its pressure more, reducing how much gas each person gets. That's on top of the difference in propellant density I mentioned earlier. If you really want to use a compressor, consider using a low-pressure compressor instead. A 12v bicycle compressor, run off a SLA battery and using a pressure-actuated switch to shut it off at the correct pressure, was the original propellant mechanism used in Big Gun ships during the 70's and 80's. It is the origin of our rate of fire restrictions, and is still perfectly functional technology today.
with co2 its more like 10 seconds and no physical effort to speak of. You arent doing a good job of selling hpa if that is what you are trying to do.
Interesting idea, Darren... I don't use one on a ship, but it'd make the one I carry in the car more uber
Sounds very interesting... Kotori and I tried putting a compressor on our first warship, a Scharnhorst way back in 2004. One of the big problems was that the brushed DC motor on the compressor kicked out a lot of electrical noise. When Scharnhorst fought in the 2004 Campaign Game, it caused more trouble for the Axis team than the Allies because of that electrical noise. A brushless motor should help a lot. You may want to gear it down to the same RPM the brushed motor achieved, so as not to overspeed or overheat the compressor. Also look into sound silencing mounts and enclosures. Those compressors are really loud and obnoxious on the water if you don't do anything to make them quieter.
By weight and volume, what would be more effiecient: a 20 oz Co2 bottle, or a brushless compressor with equivilant battery life?
Methinks that there are so many variables it would be an unequivocal "it depends." Some small ships can run on a disposable CO2 cartridge and do not have the weight and space allowance for the pump and extra electrical supply. Many large ships have electricity to spare, they get if "free" from their ballast. I do like the idea of converting an air pump to a brushless (I have a brushless water pump that is very low current draw that I am planning on installing in a ship). You could use the speed controller to get the RPMs in the right zone, I am thinking. A motor and pump CAN take up less space, and, probably weight, than a 20oz CO2 bottle and regulator, but you would probably want a volume tank / master accumulator for the system, which would use up some of that volume, but could be a pipe in the bilges, so not as wasteful of criticlal space. Cheers,
I'm thinking I might use such a system in my ship I'm building, Jean Bart... Where would one get the compresser?
the problem can be crudely bounded (or more accurately calculated but that takes more time than a cursory bounding)... consider 9oz by mass of co2... at 165psi (1.137e3 kPa) (absolute (150psi gauge) and 10C that is about 12L of co2. ignoring some minor differences in the gasses (for our purposes, mass of air per shot, actual available co2 if isothermal vs actual installed condition, etc) you need to generate about the same volume of compressed air at the same temperature & pressure, starting with, for the sake of simplicity, 101.3kPa of air. if you make the isothermal assumption for the compressor, the math becomes easy. if you take that math, factor in motor and compressor inefficiencies, you end up with a battery requirement to get in the ballpark of 9oz co2 of about 5Ah at 6V... now the real process will not follow the isothermal curve, further driving up the battery requirements... Now adding in extra capacity so you don't kill the battery by fully cycling it every time, you end up with a 6V 12AH battery + compressor + accumulator volume to replace one 9oz co2 cylinder + regulator.
