factors that affect FPS

[eleven]

based on mp5 upgrade of airsoft press..(page 71),

many people believe that batterry power does not does not matter in semi-auto, that as long as the motor has enough power to pull the piston then a shot is satisfactory completed.this concept is totally wrong, as said before a guns fps is partly determined by how fast and powerful the piston is moving forward.With enough battery power the motor can afford to pull the piston and the spring fast and hard.in return the spring will be much more powerful in its return movement and will push the piston harder.

can anyone enlighten me pls..i believe this is true since if you apply the theory regarding force and impulse the decrease in time to release the piston maximizes the momentum of the piston as it moves forward.

i'm in a debate in other forum so i want to ask some clarification here.tech gurus,physics scholars pls help..thanks.

[Tom_Keeler]

I was always under the impression that it was only dependent on the spring myself, but I don't really know for sure.

[Kid]

The motor turn the gears which pull the piston back, then it is released.

There is no reason that how fast it is pulled back would ever affect how hard and fast the spring brought it forward.

The only thing it would affect is ROF. Being how fast the piston is pulled back.

Once it is pulled back, it goes forward again, losing all momentum from going backwards.

spring, barrel, piston head, nozzel, cylinder.
thats about it

[Dirty Deeds]

The ONLY way this would be true, is if you could get a strong enough and fast enough pull from the motor to create what we call "valve float" in the automotive industry.

This is when there is so much force compressing the spring that it will actually be compressed farther than it is supposed to be compressed, and leave whatever is compressing it for a split second, because of irregular force.

Sorry best I can describe it, after being up since 2:00pm yesterday. Chances are you would only acheive this with a stock spring, high speed gears, high speed motor, and an over power battery such as a 12V. And even then you'd probably get more FPS by adding a bearing spring guide to a stock gun, and it would last longer too

So in short, Droc is dead on, just missing the bearing spring guide for spring pre-compression.

[MMMiles!]

Originally Posted by Dirty Deeds

The ONLY way this would be true, is if you could get a strong enough and fast enough pull from the motor to create what we call "valve float" in the automotive industry.

This is when there is so much force compressing the spring that it will actually be compressed farther than it is supposed to be compressed, and leave whatever is compressing it for a split second, because of irregular force.

And even if this was possible, I don't think you'd particularly want your piston to attempt to float freely in your mechbox. I doubt you could even get enough power in your system for this to occur, though.


Short answer, eleven: no, your battery does not affect your fps. This is an airsoft myth that just keeps getting repeated.

[Mantelope]

Potential spring energy is defined as E=1/2kx^2 where k is the spring constant and is specific for a specific spring. When the sector gear disengages with the piston, the piston's kinetic energy comes to a stop nearly immediately. If the sector gear is moving infinitely slowly then the piston's kinetic energy when the sector gear disengages is 0, and then the spring's energy is converted to kinetic energy. The only way this can be impacted by the speed with which the gears pull the piston back is if the momentum of the piston when the sector gear disengages is enough to continue moving against the spring and thus increase the x in the spring equation. Since the mass of the piston is so damn low compared to the force with which it is pulled by the gears, I'm going to wager that the situation I've described has practically zero impact on the muzzle velocity of a BB.

[ILLusion]

The only thing the battery/motor does is pull the piston back. On release, it's all up to the spring to perform the forward movement / compression cycle.

[eleven]

for every action there is an equal and opposite reaction...a ball would bounce back harder if you release it with more force.. im thinking if it can be related to the spring that is pushed back and hard and released instantly..

secondly, to lessen the force of a moving object..you need to decrease the time and vice versa..where time is in respect responsible for the release of force.

imagine starting a car..the faster you release the clutch..the faster you go gaining momentum.the principle of gas expansion can also prove that time is responsible for greater force.the instant release of pressure in gas-gun propels the projectle faster with more energy.this can also be true that the faster pull the spring the harder it can go forward.

this is not to say i'm fighting with this theories...so please dont make this a reason to flame..just a friendly discussion guys..

maybe some guys form airsoft press can say something..

good day to everyone

[Mantelope]

But it doesn't matter how fast the piston goes back as long as it starts going forward at the same point. The spring possesses the same potential energy at that point no matter how fast or how slow it's compressed.

[foxtail]

To help you out I went out and tested things for you since I have shit loads of stuff.

My
M16A3 with a 7.2v 1500 mil bat = 389,385,391 fps with .20's
M16A3 with a 8.4v 1500 mil bat = 390,388,386 fps with .20's
M16A3 with a 8.4v 3300 mil bat = 384,388,392 fps with .20's
M16A3 with a 9.6v 600 mil stick = 390,385,284 fps with .20's

same gun same fps range.

[eleven]

thanks for the data its making me believe your right..do you have a 9.6 volts w/ higher mah rating..because the flow of current has something to do with it.

good day bro

battery has ZERO effect on fps. All it effects is ROF.

[The Saint]

Next time this comes up, just tell them to find a door knob. Turn the knob and release it. No matter how faster you turn the door knob, as long as you just let go and always at the same point, it will spring back with the same amount of force every time.

[Dirty Deeds]

Originally Posted by eleven

for every action there is an equal and opposite reaction...a ball would bounce back harder if you release it with more force.. im thinking if it can be related to the spring that is pushed back and hard and released instantly..

secondly, to lessen the force of a moving object..you need to decrease the time and vice versa..where time is in respect responsible for the release of force.

imagine starting a car..the faster you release the clutch..the faster you go gaining momentum.the principle of gas expansion can also prove that time is responsible for greater force.the instant release of pressure in gas-gun propels the projectle faster with more energy.this can also be true that the faster pull the spring the harder it can go forward.

this is not to say i'm fighting with this theories...so please dont make this a reason to flame..just a friendly discussion guys..

maybe some guys form airsoft press can say something..

good day to everyone

You are comparing Apples and Oranges here, a clutch harnesses the power of your engine. Yes there are springs in the pressure plate, however these are for applying force to the clutch plate, which in turn puts force on your flywheel, therefore the quicker you you release the clutch pedal the quicker you harness the power of the engine, hence the quicker take off or launch.

You have 6 guys telling you that the battery has nothing to do with FPS, 6 guys who I believe know their stuff. Do you need more convincing look at Illusions profile http://www.airsoftcanada.com/member.php?u=603

I'll quote what you should be looking for:

Occupation:
De-virginizing gearboxes since 2002

Nuff said.