From Polarstar we have the JACK Drop-in HPA Engine for the S&T TAR-21.
The JACK™ was designed to answer the demand for an affordable, high performance HPA (High Pressure Air) conversion for AEG's. The system is a drop-in cylinder replacement that is universally compatible with a wide range of gearbox versions that have center-line nozzles.
Similar to its sister products, the JACK™ replaces the original gearbox components with a programmable pneumatic system allowing for higher performance and greater reliability over a gear driven system. Although economically priced, the JACK™ still retains the same performance and quality you have come to expect from PolarStar products.
The JACK™ has only one moving part, the nozzle, which acts as its own poppet valve. Similar to the Fusion Engine™ and F2™ poppet, the nozzle is only piloted by the solenoid to open air flow through the poppet with none of the firing air coming from the solenoid itself. This design lets the JACK™ send a higher flow of air down the barrel than systems that only use a solenoid as the firing valve.
User Manual: https://cdn.shopify.com/s/files/1/0023/7466/4301/files/JACK_Instructions_080721.pdf?v=1628356512
All kits come with an FCU, Switchboard, Wire Harness and any additional components needed to convert the specific airsoft rifle model for which the kit is configured.
Polarstar Supplied Test Results: (Test Configuration: 6.05x375mm Barrel, Location: United States of America)
Velocity: 500fps w/ .20g @ 130psi - The JACK™ allows for easy velocity adjustment by changing input pressure and does not require different nozzles to reach its full velocity range. Using a standard M4 as an example, velocity can be adjusted from below 280fps and up to approximately 500fps with a .20g BB. Velocity can vary per model as longer barrels will increase the maximum velocity while shorter barrels will decrease it.
ROF: 30rps - The maximum cyclic rate of the JACK™ is affected by several factors such as the operating pressure as well as quality of the magazine and BB's used. However, 30 rounds per second is achievable in most standard configurations.
Air Efficiency: 1000+ shots from 13/3000 @ 1.5J w/ .28g - Although not a critical requirement during development, JACK™ does boast some highly respectable figures in this category. This is made possible by its intelligently laid out design which minimizes dead volume resulting in better air flow, faster response and less air used per shot.
