I've calculated it would require approximately 37 pounds of force to unseat a 9/16" ball valve @ 150 PSI (rough calculation.... You engineering types.. please don't brow beat me[B)]) The required travel is .1875" (3/16)
Yup; you got it. In Big Gun the only flow that matters is what comes out of the 'buna?' ball valve. The buna trigger needs pressure not flow. I'm sure you could do this with a regular electronic actuator. But I have no idea how much torque it would require. My guess is quite a bit. But, I really have no idea.
It seems as if an electric plunger type actuator would do the job. I just haven't been able to find one with a similar size / configuration to the MPA-7 that could be attached in place of the MPA-7 and function about the same way.
Cool. Additionally it can be instantaneous; because once the valve is open it doesn't close until the accum is empty. & it closes naturally without help, right? SO, you need a solenoid to deliver a 40lb 3/16" punch. If you assume the solenoid has momentum & the ball is lightweight; I'd bet its doable. Hey you physics nutzz.. step up in here anytime.
Yes, the buna ball will return to seat on it's own. I'm not sure if it will remain open until the accumulator is empty though?? Now that you mention it, if the solenoid had a little free stroke before contacting the buna ball assy. it would carry kinetic energy, which should reduce the force requirement... but that is way beyond my calculating capability[V]
40 pounds? Hmmm... let me do some looking and asking. Getting 40 pounds with a 6V system will be... interesting. Most small solenoids are rated in ounces. I found some car door solenoids that are rated for 40#, but they're 12V and I'd bet that dropping the voltage by half would not help output.
Hmmm... wow, yeah. I remember one guy in the WWCC who triggered torpedo cannons directly using a servo, instead of an MPA actuator. He said he couldn't pump it up more than 100 PSI otherwise the valve wouldn't open. He has since switched to using an MPA-5. I don't know if 40 lbs is really necessary to open a Big Gun ball valve. MOST big gun cannons (except the ones I build) have a valve aperture of 3/8" to 1/2".
Exactly, I wouldn't think you need 40 lbs if you build up enough momentum ie.. add weight & speed. But I'm not a mech engr; so don't listen to me.
I'm sure the 40 lbs is probably overkill.. or more of a worst case scenario. Like Kotori said, the hole is a bit smaller than the ball. It is still a substantial amount of force required from a small package. Aren't the MPA-7s made with a 5/8 diameter bore? If they are, they only deliver approx 46 lbs of force @ 150psi I'll look it up when I get a chance.
Right you are Tugboat... so with a 7/8 bore... that's about 90 pounds of force @ 150psi It would take a mighty beefy electric soleniod to supply that much force.[]
Having zero experience with big gun cannon (yet), I can't say how many big gun guys run their cannons at 150#, though. From the reading I've done, many have to reduce their pressure in order to pass the foam test. You might not need nearly as much pressure as the system is capable of reaching...
But those solenoids are very quick, and they have a reasonable mass. Lets say the solenoid weighs .5 oz (never weighed one, but seems reasonable) and lets say (I really have no idea..) it can travel 300 mph. (who knows) That's 10lbs impact on the ball. (ASSUMING I REMEMBERED MY PHYSICS CORRECTLY... IF I'M WRONG>>>> STOP ME NOW) So, if we can increase the weight of the pin to 5 oz & assume only small drop in speed... --> That's ~93lbs applied to the ball. The 4.5oz difference is ~1 cu.in. of iron to be attached to any moving part of the solenoid. ---- I think I've jumped off the deep end to theoretical land. I'd just use the existing design, save yourself all the hassle.
I guess it would be easiest to just do it this way: use an RCE200 to trigger an EV-3-6-H valve to supply air to a MPA-7 to push open the buna ball valve But you can't say the discussion wasn't a lot of fun[]
Can anyone answer just one last question: How much force would it generate if we were to have a rabid gorilla with some type of random decoration strapped to his head (preferably a heavy one -- 3-4 lbs) launched from a 17 ft long rubberband into the end of the buna valve?? For this purely hypothetical situation lets assume the gorrila accelerates to 63 MPH before leaving the rubberband, the relative humidity is between 40-50%, no head wind, and the gorilla is flying feet first, with a coefficient of drag of approximately .42, with a distance of 7 feet between being released by the rubberband and the point where he recieves blunt force trauma from the buna valve. This all assumes that the ship is large enough to accomadate this weapon system. Disclaimer: The proceeding is intended purely for entertainment purposes. Any similarity between this situation and an actual situation are coincidental. No actual gorillas were harmed due to the typing of this very funny comedy material. If the hypothetical gorilla had a name, it would have been changed to protect the innocent.
AAAHH.... Piss off! [:0] I'm going to go sob alone in my corner & play with my friends... (all me of them.) [V] [][][)]
No torque; it's a linear motion, not rotary. Most solenoids pull, you'd need to push. Mounting would be the big challenge, I think. Look up specs on what the MPA-7 does & find a push solenoid that can do the same. JM
Unscrew the MPA-7 & just TRY to push the rod when the accumulator is pressurized. Then, try to hit it with a hammer & see if you can get it to open... JM
The site doesn't say... However, isn't it just a little pneumatic pushrod? So wouldn't it be the same pressure as the CO2 behind it? So 150psi? Which is why the accumulator pressure is usually a little lower, so there is a pressure difference?
