very technical mag valve questions

[Chris Nearchos]

okay, so i was sitting in a physics final today and really got the brain cells firing. really just cant shake this thought and need to get some info to work it out. if anyone has any answers to the questions, please by all means post up.


and I guess i better state where this is going just to get a bit of intrest. this will either turn into a new valve for mags or even a whole new marker. and I do have to add that its operation isnt something that i have seen any marker on the market do.


and yes, i know if i spent a good couple days searching around i could find the answers. but with finals going on right now, I cant spend that kind of time atm.


Q) what is the general pressure excerted onto the ball in the breech when the bolt makes contact?

Q) what is the general output pressure excerted onto a ball by the air when being fired?

Q) what is the max spring pressure the internal spring lip in a mag body can take on?

Q) why must one use a sear and standard on/off in a mag? oh no! looks like i will be going outside the box.......

Q) how much output air pressure (for a standard mag valve) is needed to counter act the force of the spring and to move foward?

Q) how far forward must the bolt be from locked position, for the firing action to work properly?

Q) what is the resetting time on a mag bolt? (lvl 7 in mind)




now yes, i already know that the pressure is different due to the pressure/velocity settings. But in general, what would these figures look like?

thanks for the help ahead of time,
-Chris

[athomas]

okay, so i was sitting in a physics final today and really got the brain cells firing. really just cant shake this thought and need to get some info to work it out. if anyone has any answers to the questions, please by all means post up.


and I guess i better state where this is going just to get a bit of intrest. this will either turn into a new valve for mags or even a whole new marker. and I do have to add that its operation isnt something that i have seen any marker on the market do.


and yes, i know if i spent a good couple days searching around i could find the answers. but with finals going on right now, I cant spend that kind of time atm.


1. Q) what is the general pressure excerted onto the ball in the breech when the bolt makes contact?

2. Q) what is the general output pressure excerted onto a ball by the air when being fired?

3. Q) what is the max spring pressure the internal spring lip in a mag body can take on?

4. Q) why must one use a sear and standard on/off in a mag? oh no! looks like i will be going outside the box.......

5. Q) how much output air pressure (for a standard mag valve) is needed to counter act the force of the spring and to move foward?

6. Q) how far forward must the bolt be from locked position, for the firing action to work properly?

7. Q) what is the resetting time on a mag bolt? (lvl 7 in mind)




now yes, i already know that the pressure is different due to the pressure/velocity settings. But in general, what would these figures look like?

thanks for the help ahead of time,
-Chris

1. I don't know the exact spring constant, but I'm estimating the force exerted on the ball is around 15 lbs for a level 7 mag and between 1 and 5 lbs for a level 10 mag with the middle spring.

2. Behind the ball pressure never reaches above 60psi in a mag.

3. What do you mean "spring lip"?

4. Sear holds the bolt in place. Without the sear holding the bolt in place it would pop like a cork and release the air in the chamber, which it does when the gun is fired. The on-off pin closes the air inlet before the bolt is released so that a controlled volume of air is released.

5. Its not the force to move the spring, but rather the force needed to fully compress the spring that is needed. A bolt spring that is uncompressed only takes a fraction of a lb of force to move, but as the spring is compressed more energy is stored up in the spring. Therefore, as it compresses, more and more energy is needed compress it further. For example (not real numbers) if it takes 2lb to compress the spring 1/8", it will take 4 lbs to compress it 1/4", and 6 lbs to compress it 3/8". This is actually part of the problem. We need lots of force to full compress the spring, but need a gentle start to keep the ball from being crushed. This is why the level 10 bolt was developed with a smaller starting piston for a gentle start and a larger final diameter to provide power to fully compress the spring.

I don't know the actual air pressure at the minimum cycle setting.

6. Most breaches are about .750" across. The bolt must cross this distance to properly seal the barrel when firing a shot.

7. I can't remember this one.

[Spider-TW]

okay, so i was sitting in a physics final today and really got the brain cells firing. really just cant shake this thought and need to get some info to work it out. if anyone has any answers to the questions, please by all means post up.


and I guess i better state where this is going just to get a bit of intrest. this will either turn into a new valve for mags or even a whole new marker. and I do have to add that its operation isnt something that i have seen any marker on the market do.


and yes, i know if i spent a good couple days searching around i could find the answers. but with finals going on right now, I cant spend that kind of time atm.


1. Q) what is the general pressure excerted onto the ball in the breech when the bolt makes contact?

2. Q) what is the general output pressure excerted onto a ball by the air when being fired?

3. Q) what is the max spring pressure the internal spring lip in a mag body can take on?

4. Q) why must one use a sear and standard on/off in a mag? oh no! looks like i will be going outside the box.......

5. Q) how much output air pressure (for a standard mag valve) is needed to counter act the force of the spring and to move foward?

6. Q) how far forward must the bolt be from locked position, for the firing action to work properly?

7. Q) what is the resetting time on a mag bolt? (lvl 7 in mind)




now yes, i already know that the pressure is different due to the pressure/velocity settings. But in general, what would these figures look like?

thanks for the help ahead of time,
-Chris

1.& 5. I have never seen the spring constant either. You would have to take a known weight like athomas said and measure the response. The actual firing force held by the sear will be the area of the level 7 stem end times about 425 psi, but the required starting force will be just a little more than the minimum compression from the spring.

2. I would take athomas' number.

3. Once you figure out the spring constant, you can figure about .75 inches displacement and call that maximum force. The actual problem is that the failure will normally be from fatigue, so you need to consider the fabrication method and number of cycles you expect from a lifetime if you think you will be pushing the design further.

4. It's reliable. Electronic or mechanical sequencing of the on/off and sear as separate devices would lead to complications and expense for little payback. New electronics and components might be equal in the end though.

6. Looking at the power tube geometry, you probably get full flow when the bolt stem clears the power tube spacer by about 1/8", so that's about 3/8", but the bolt is moving forward and you won't get full effect until the dump chamber has emptied and the ball has entered the breech. The way the mag is setup, if it doesn't reach the breech, it probably didn't have enough pressure for good velocity anyway.

7. Use an RT fired mag as the maximum cycle time and take off the x-valve recharge time of 30 ms. Say 20 bps, for 50 ms cycle time and subtract 30 ms for about 20 ms bolt out and return. Ballparking of course.

[Chris Nearchos]

thanks

thanks for the help fellows. Very much appreciated.

and as for the "spring lip" I am refering to is the "lip" in the body that stops the sprig where it should be held.



hmm, maybe tom or one of the AGD techs could ring in on some of the hard figures.

thanks again fellows,
-Chris