SpudFiles

Yeah, but how do you know whether you fired for 1 second, or 1.01 s, or even .99s - perhaps .9 secs

You can't know for certain, and that will affect the exact figure you get. The first method (timing how long it takes to fire 500) is the most accurate.

@Judgement_arms: I'm not sure that is true. My physics tells me that isn't right. The exact thought train I'm using is too long for a sensibly sized post, but you'll lose as much energy as the BB is going away from the magnet as you'll gain when it approaches.

Energy can't come from nowhere, and unless the magnet provides energy by slowly demagnetising itself (which is a potential source of energy, but not ideal - as a good magnet is expensive), it's not going to work.

However, it could be used for a hop-up system, by using a magnet to pull the BBs upwithin the barrel so that they gripped the top, meaning that they'd gain backspin.

judgment_arms wrote:They say a picture’s worth a thousand words:

This is only a partial solution to the rampant waste of air intrinsic to the cloud and BBMG designs. I know I'm overpromoting the idea, but if you use the concept I proposed, the chamber is *already* pressurised, no dead space and therefore maximum efficientcy

jackssmirkingrevenge wrote:Er... as opposed to just counting the amount of BBs in your chamber before you pulled the trigger compared to the amount of BBs after you let go of it?

It would be easier to count 100 bbs than 500 bbs

edit:@ joannaardway: Shouldnt be too hard to fire for 1 sec with a stopwatch. The only problem I could see with that is the pressure decrease, but I assume a big enough chamber is being used to counter this.
Anyway, who needs to be THAT accurate with ROF predictions?

Again, back to the exact timing issue - short of doing it digitally, you're not going to get exactly 1 second.

Maybe not, though I could hook up a solenoid alve as a trigger, connected to a timer. But I'll just time how long it takes to empty the chamber, it's a lot easier and more accurate to do.
Clide, I'm doing the tests anyway. People should still believe that cell core and ABS shouldn't be used for pneumatics. If not, it's not my problem. I'm just trying to "contribute" in a helpful way.

The only way you are going to get accurate results is by what Joanna said....Buy several packets of 500bbs each,regulate the pressure to what you are going to use(80psi?) then time each test...you will end up with a few time trials, make sure they are in seconds ad them together then divide by how many tests you do and thats a accurate average number.
e.g 500bbs T1 T2 T3
4.7s 5.2s 4.9s add them together you get 14.8
14.8 divide by 3 gives you and average time of 4.93*seconds

Yep. Probably going to do 3 trials at each pressure and average the time, with 70 psi, 80 psi, 90 psi, 100 psi, and 110 psi.

Ok, I agree. They dont sell 500packs of bbs at my walmart but yeah that would definatly be easier if you have them.

The only bad thing about testing abs is that people become more trusting of it when they have solid data, and eventually someone will blow an eardrum out when an abs chamber fails. I would use abs for barrels, but not to contain sustained high pressure.

if your going to just use magnets you should just build a rail gun

Rail guns dont contain magnets. Stop playing so much quake.

no but they do use a magnetic field/force thing i was planning on making one but it was to much work and i dont have enough capacitors

noname wrote:I'm just trying to "contribute" in a helpful way.

I know, and I respect you for that. I'm just trying to prevent you from wasting your time and money on tests that hold virtually no value beyond your specific circumstances.

The BBMG tests would be nice, as there is a distinct lack of useful comparison data.
A good way to collect data for a BBMG would be the homemade chrony that jimmy from Spudtech uses. It would allow you to collect very accurate data for average velocity and rate of fire. It's fairly simple and cheap. If you are interested and not sure what I'm talking about I can try to find a link.

clide wrote:A good way to collect data for a BBMG would be the homemade chrony that jimmy from Spudtech uses. It would allow you to collect very accurate data for average velocity and rate of fire. It's fairly simple and cheap. If you are interested and not sure what I'm talking about I can try to find a link.

jimmy's chrono & rof meter

I don't know if I'd make that, anything I ever make using more than 5 electrical compaonents doesn't work. Might as well give it a try?

noname wrote:I don't know if I'd make that, anything I ever make using more than 5 electrical compaonents doesn't work.

In that case, you're in luck!



Honest, it's really not that complicated.