Post by SANDMAN on May 4, 2008 0:50:04 GMT 8
SYSTEMA Revolution: Benefit of a Shorter Piston
Introduction
We've received some comments in the past from keen-eyed users that our PTW's piston is shorter then TM pistons, and as we deploy the same piston in the Revolution, the question of "why" naturally arises. In this white paper we will examine why shorter pistons do not negatively affect the output power in the Revolution, and what other benefits it brings.
Bigger piston = More Power: Myth or Facts?
First of all, a bit of myth busting: traditional wisdom says the bigger the air volume inside a cylinder (by either increasing bore with bore-up cylinder kits, or increasing stroke by using longer pistons such as PSG-1), the higher the power. This is only partially true. In older TM design, bigger air volume is actually needed to fight air leaks more so then anything else. This can be proven mathematically: traditional TM cylinder at ~23.75mm I.D. with a stroke of ~47mm will provide approximately 20,800 mm3 of volume. However, the longest barrels used in Version 2 Mecha Box (M16, at 509mm length), even assuming it is not a tight-bore barrel (say, 6.5mm I.D.), only has approximately 16,900 mm3 of volume. Even considering increased frontal pressure against the BB during firing, air leakage around the BB, and other void area (such as inside the nozzle or hop-up), there are still plenty of air available. Therefore, what we've found out over the year is that efficient use of the available air is far more important. By creating a better air-seal around critical components such as piston head or nozzle, the additional air volume is no longer necessary (you can almost say it would be wasted). Therefore, we decided to reduce the piston travel so that we can gain other benefits.
Fact #1: Lower Power Consumption
The benefits from a shorter piston may seems trivial but are often considered extremely important to expert gunsmiths. First of which is power consumption. By increasing air-seal efficiency and shortening the stroke, the Revolution's piston does not have to travel as far compare to a TM piston. This means the duration of motor operation on each stroke is now shorter. Because the spring tension does not change (we are using air-seal efficiency, not stronger springs, to compensate for the shorter stroke), each cycle in the Revolution will now consume less energy then a comparably configured TM mecha box. On many highly customized AEGs with minimal space for battery storage, reduced power consumption is highly desirable.
Fact #2: Faster Trigger Response
Secondly, by reducing stroke length we can also improve trigger response time. Naturally, if the piston takes less time to withdraw, then the time delay between the player pulling the trigger vs. the AEG actually firing will be reduced. In some hair-splitting situation during skirmishes, even a 0.05 seconds of delay could mean the difference between hitting and missing your target.
Fact #3: More Durable Mecha Box
Thirdly, shorter piston travel also improves reliability. Since we did not change the sector-gear's diameter, it retained the same circumference length thus shifting the ratio between the sector gear's "engaged" and "disengaged" duration (i.e. whether the sector gear is pulling the piston or just free-spinning). Compare to a traditional TM setup, the Revolution's sector gear spend more time disengaged (free-spinning). During full-auto operation, this gives the piston more time to "fire" (reset itself to the forward position) before the sector gear engages it again. Combined with the short-stroke nature (which also reduces "firing" time), the chance of the Revolution's sector gear prematurely engaging the piston (against the wrong tooth) is significantly reduced. Since premature engagement of the sector gear is the #1 cause of catastrophic failure in upgraded mecha box, the Revolution's short-stroke design will significantly improve its reliability. This is particularly noticeable if the user experiences a jam during full-auto firing. Because of back-pressure build-up, a jammed gun will slow down the piston during its forward movement. However, since the sector gear remains at the same rotational speed, the chance of premature sector gear / piston engagement is now increased. The Revolution, compare to traditional TM setup, allowed for a larger margin of error during such events because its sector gear has a longer free-spin duration.
Fact #4: Wider Shoulder for High ROF Setup
Finally, the different engaged vs. disengaged ratio in the Revolution also enables expert gunsmiths to achieve more reliable high rate-of-fire (ROF) operations. In many extremely high ROF setup (in excess of 35 rounds per second), gunsmiths must take careful consideration of the necessary time for the piston to return to the forward position after its "released" by the sector gear (we call this action the "firing stroke"), against how fast the sector gear can re-engage the piston after each "release" (we call it the "window"). Basically, if the "window" closes before the "firing stoke" completes, the sector gear will engage the piston on the wrong tooth causing catastrophic failure. Some gunsmiths loosely refer to these incidents as "timing error". Generally, in high ROF setup, "timing errors" are far more common because the "window" is only marginally larger the the piston's "firing stroke" time. By shifting the ratio of the sector gear's engaged vs. disengaged time, we were able to lengthen the window, thus allowing expert gunsmiths more shoulder room to push their limits.
Conclusion
In conclusion, by improving the Revolution's efficiency, we can afford to shorten the piston's size / travel without any negative impact to the maximum power output. Though this change, we can then lower power consumption, improve trigger response, and creates a more reliable mecha box setup. In the end, it is the pursuit of perfection that prompted our engineers to leave no stone un-turned, bringing the highest performance to our loyal users.
Introduction
We've received some comments in the past from keen-eyed users that our PTW's piston is shorter then TM pistons, and as we deploy the same piston in the Revolution, the question of "why" naturally arises. In this white paper we will examine why shorter pistons do not negatively affect the output power in the Revolution, and what other benefits it brings.
Bigger piston = More Power: Myth or Facts?
First of all, a bit of myth busting: traditional wisdom says the bigger the air volume inside a cylinder (by either increasing bore with bore-up cylinder kits, or increasing stroke by using longer pistons such as PSG-1), the higher the power. This is only partially true. In older TM design, bigger air volume is actually needed to fight air leaks more so then anything else. This can be proven mathematically: traditional TM cylinder at ~23.75mm I.D. with a stroke of ~47mm will provide approximately 20,800 mm3 of volume. However, the longest barrels used in Version 2 Mecha Box (M16, at 509mm length), even assuming it is not a tight-bore barrel (say, 6.5mm I.D.), only has approximately 16,900 mm3 of volume. Even considering increased frontal pressure against the BB during firing, air leakage around the BB, and other void area (such as inside the nozzle or hop-up), there are still plenty of air available. Therefore, what we've found out over the year is that efficient use of the available air is far more important. By creating a better air-seal around critical components such as piston head or nozzle, the additional air volume is no longer necessary (you can almost say it would be wasted). Therefore, we decided to reduce the piston travel so that we can gain other benefits.
Fact #1: Lower Power Consumption
The benefits from a shorter piston may seems trivial but are often considered extremely important to expert gunsmiths. First of which is power consumption. By increasing air-seal efficiency and shortening the stroke, the Revolution's piston does not have to travel as far compare to a TM piston. This means the duration of motor operation on each stroke is now shorter. Because the spring tension does not change (we are using air-seal efficiency, not stronger springs, to compensate for the shorter stroke), each cycle in the Revolution will now consume less energy then a comparably configured TM mecha box. On many highly customized AEGs with minimal space for battery storage, reduced power consumption is highly desirable.
Fact #2: Faster Trigger Response
Secondly, by reducing stroke length we can also improve trigger response time. Naturally, if the piston takes less time to withdraw, then the time delay between the player pulling the trigger vs. the AEG actually firing will be reduced. In some hair-splitting situation during skirmishes, even a 0.05 seconds of delay could mean the difference between hitting and missing your target.
Fact #3: More Durable Mecha Box
Thirdly, shorter piston travel also improves reliability. Since we did not change the sector-gear's diameter, it retained the same circumference length thus shifting the ratio between the sector gear's "engaged" and "disengaged" duration (i.e. whether the sector gear is pulling the piston or just free-spinning). Compare to a traditional TM setup, the Revolution's sector gear spend more time disengaged (free-spinning). During full-auto operation, this gives the piston more time to "fire" (reset itself to the forward position) before the sector gear engages it again. Combined with the short-stroke nature (which also reduces "firing" time), the chance of the Revolution's sector gear prematurely engaging the piston (against the wrong tooth) is significantly reduced. Since premature engagement of the sector gear is the #1 cause of catastrophic failure in upgraded mecha box, the Revolution's short-stroke design will significantly improve its reliability. This is particularly noticeable if the user experiences a jam during full-auto firing. Because of back-pressure build-up, a jammed gun will slow down the piston during its forward movement. However, since the sector gear remains at the same rotational speed, the chance of premature sector gear / piston engagement is now increased. The Revolution, compare to traditional TM setup, allowed for a larger margin of error during such events because its sector gear has a longer free-spin duration.
Fact #4: Wider Shoulder for High ROF Setup
Finally, the different engaged vs. disengaged ratio in the Revolution also enables expert gunsmiths to achieve more reliable high rate-of-fire (ROF) operations. In many extremely high ROF setup (in excess of 35 rounds per second), gunsmiths must take careful consideration of the necessary time for the piston to return to the forward position after its "released" by the sector gear (we call this action the "firing stroke"), against how fast the sector gear can re-engage the piston after each "release" (we call it the "window"). Basically, if the "window" closes before the "firing stoke" completes, the sector gear will engage the piston on the wrong tooth causing catastrophic failure. Some gunsmiths loosely refer to these incidents as "timing error". Generally, in high ROF setup, "timing errors" are far more common because the "window" is only marginally larger the the piston's "firing stroke" time. By shifting the ratio of the sector gear's engaged vs. disengaged time, we were able to lengthen the window, thus allowing expert gunsmiths more shoulder room to push their limits.
Conclusion
In conclusion, by improving the Revolution's efficiency, we can afford to shorten the piston's size / travel without any negative impact to the maximum power output. Though this change, we can then lower power consumption, improve trigger response, and creates a more reliable mecha box setup. In the end, it is the pursuit of perfection that prompted our engineers to leave no stone un-turned, bringing the highest performance to our loyal users.