HUNTER HPA HYBRID CONVERSION KIT – WHAT IT IS AND HOW DOES IT WORK

HUNTER is a hybrid HPA engine designed for installation in electric gun replicas equipped with V2 and V3 gearboxes. It is called a hybrid for it combines the best features of electric drives along with the performance and capabilities of HPA systems. It allows to transform the drive of a gun replica from purely electrical to gas. Depending on the length of the barrel and the set pressure, it may serve as the drive for replicas intended for CQB as well as the strongest sniper rifle replicas.

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HUNTER replaces the cylinder and piston assembly. In contrast to other such solutions, the kit uses some of the elements from the conventional AEG system. Its main characteristic is the use of pinions and electric engine to open the valve, which is the base for any HPA conversion kit. Power offered by such combination ensures seamless work in each pressure range as well as simplifies the construction. What distinguishes the functioning of HUNTER from AEG systems are, besides excellent performance, negligible forces affecting the elements within the replica. It is not possible to damage the construction, its front-end is not subject to any strain whatsoever. Furthermore, the functioning of pinions in HUNTER conversion kit at the highest permissible pressure corresponds just to a fraction of work on springs with the lowest denominations. Thanks to this solution as well as the design that prevents jams described below, damaging the pinions becomes almost impossible.
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The development of the engine was accompanied by a concept of creating a malfunction-free device. The developers based their work on the result mentioned in one of the interviews by the creator of AK rifle, Russian doctor of technical sciences, Mikhail Timofeyevich Kalashnikov (Михаил Тимофеевич Калашников)

“…I could pour a handful of sand into the rifle, retract the bolt latch and shoot!”

Of course, in case of replicas, or HUNTER itself, we ought not to take this statement literally. This idea is reflected in the technical assumption for fitting movable parts within the device. Components that perform the stroke movement are loosely fitted, their place of contact has been nullified to a minimum while the surface was polished so as to reduce friction. The core of the conversion kit may deviate from the working axis without causing complications in the functioning of the entire system. It is impossible to block this motion.

CURIOSITY

During prototype works the creators conducted a test where HUNTER was tested grease-free in semi- and full-auto modes at -10°C. No problems were detected in terms of functioning even after several thousand shots fired. Despite the obtained results, using HUNTER without lubrication can cause damage to the o-ring, therefore it is not recommended.

While writing about the design of HUNTER, one should specify the materials and technologies used for its production. All components are manufactured with the use of modern CNC machines operated by a highly qualified team of specialists with several decades of experience. Due to its functional attributes, the developers resigned from materials such as aluminum and, in their place, decided in favor of high-class bronze, constructional steel, stainless steel and hardened steel used, among others, by both mining and arms industries. Plastic components made of graphite-based polymer were applied in convenient places enabling such application. Its characteristics ensure high durability, wear resistance and exceptional self-lubricating properties. In case of the most extensively exploited points within the system, the creators took advantage of the technology of removable leading edges that allows to replace potentially worn-out components. Tungsten carbide with extreme properties was used in these places. Due to basic parameters such as ultra small sinter grain, high density and hardness ranging between 92 and 93 HRA, details made out of this material are almost indestructible. Another interesting part is the core of the conversion kit. In addition to the fact that each piece is manually polished for a smooth surface and suitable fit of components, it is also subject to PUK precise welding process. Bonding metals in accordance with this technology is conducted under a microscope, which ensures unprecedented accuracy and top-tier quality of welds.
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WHAT DO WE GAIN BY USING THIS SOLUTION

Using drive gear yields an abundance of benefits. The basic is the already mentioned seamless operation at any pressure range. Due to a large stock of power, resulting from the use of an electric motor, for HUNTER there is no difference whether it operates at 3 or 11 bar. At the same time, such excess makes power consumption several times lower when compared to AEG replicas. Imagine that you own a light car in which you install a very powerful engine. It rides perfectly and, at the same time, it does not burn much fuel. Thus, you can successfully apply batteries with smaller capacities. This is however not a requirement. The kit may be also charged by batteries with higher capacities, the only difference here will be a longer duration of discharge.

Another advantage is the implementation of nozzle motion in a manner known from AEG platforms. HUNTER accepts all NBU nozzles available for sale and their motion is generated through a slightly modified tappet. Thus, it does not waste gas to move the nozzle and obtains a favorable pressure – FPS ratio. Ensuring proper sealing on the connection between the nozzle and the hop-up bucking does not constitute a problem. All service solutions known from AEG platform designed to seal the system may be also applied upon installing the HUNTER engine.
Another advantage of this construction, and also a benefit for the owner, is the use of mosfet systems, designed to ensure control over HUNTER. The user is not required to use a dedicated driver. Upon making a selection he is able to rely on his own experience and knowledge, preferred parameters and the size of his wallet. He can also use the already existing systems. A requirement is to equip mosfet with ACTIVE-BRAKE feature. If it does not contain it, it cannot control the conversion kit. Depending on the mosfet, there is an opportunity to shoot in either single fire, continuous fire or burst mode. More information can be found further below.
It is worth underlining the fact that anyone who can perform electric replica servicing will be also able to properly install and commission HUNTER. Shimming, electric engine thrust setting and treatments related to running current installation remain unchanged. There is no need to program the device. The only case when this may be needed is the installation of an advanced mosfet driver. The mechanical part of the conversion kit was calibrated in-factory. Propeller dosing is implemented through a tank, the volume of which is adjusted manually via reduction located inside. The time of opening of the valve is selected mechanically to ensure that the conversion kit releases all of the gas each time, even using the full volume of the tank. During the shot the supply is cut off, thus preventing distortion of the propeller dose. Thus, installing the HUNTER engine does not require knowledge beyond the scope of electric replicas.

ELEMENTS REQUIRED FOR PROPER FUNCTIONING OF THE KIT

GEARBOX SHELL

HUNTER fits in almost all V2 and V3 gearboxes. The exception are V2 versions with additional reinforcement in the area of the pinions and the spring guide.Installation in such cases is possible yet requires more advanced modifications.

PISTON/SPRING/CYLINDER/HEADS

HUNTER replaces these components. You can remove and forget about them.

MOSFET

Due to its manner of functioning and scope of work, HUNTER requires to stop the system in resting position immediately after firing a shot. The effect of partial spring tension known from AEG platform is unwanted here. It may contribute to incorrect propeller dosing, firing empty shots, deterioration of trigger response, etc. Therefore, do not use the conversion kit without a mosfet equipped with a brake and do not turn off this feature, even in systems in which this option is available. This also applies to the use of full-auto mode in electric replicas not equipped with cycle detection.

– ADVANCED MOSFET SYSTEMS

The most preferred type of drivers are those equipped with pinion cycle detection. This solution allows to take full advantage of the possibilities offered by the conversion kit. Thanks to thorough control over the mechanism, they provide the ability to use the device in semi-auto, full-auto as well as burst mode along with its derivatives. Such systems are often equipped with extensive options. It is important to remember to never deactivate the ACTIVE-BRAKE feature and do not use PRE-COCKING. The reason for the first condition is described above and the effect of initial spring tension constitutes an integral feature of HUNTER. The total work of the core of the conversion kit closes at a distance ~10 mm and the opening of the valve is turned on by the core at around half of this distance. Due to the combination of this correlation with the phenomenal responsiveness of the system due to low overload, the shot is fired almost immediately after the pull of the trigger. The use of PRE- COCKING could also contribute to firing empty shots and unnecessary loads on the conversion elements.

– SIMPLE MOSFET SYSTEMS

The second group of mosfets are the simple systems not equipped with cycle detection, but equipped with ACTIVE-BRAKE feature. Such drivers give the ability to handle the conversion kit only at single fire mode. This option is dedicated to users wishing to use HUNTER for sniper purposes, where full-auto is not required. It should be noted that the possibility of switching the fire mode to continuous fire should be blocked by the user of the replica. The use of this mode may lead to malfunctions similar to those in case of using HUNTER with mosfet without the active brake feature. However, there is a way to use the system without cycle detection, not only in the single fire mode. Such opportunity is ensured by features with programmable BURST time. Smooth operation of the system can be maintained upon appropriate calibration of this parameter. However, it should be noted that modifying the reducer or using another battery may cause the need to re-calibrate the system. With this option it is not advisable to use power sources which significantly change their output parameters in the course of discharge.

GEARS

HUNTER comes with a dedicated module that replaces piston sprockets and fits the standard type AEG-type pinions. To ensure proper functioning of the system it is necessary to have an engine and middle pinion with 18:1 transmission ratio, available in factory-made gearboxes. Due to the design of the conversion kit, it is not necessary to use expensive, reinforced gears. Use of the anti-reversal latch depends on the installed Mosfet driver. It should be removed only if the manufacturer recommends it, in other cases it should remain in place. It is also worth mentioning the ongoing works on the DUAL SECTOR GEAR module. In the future, it will allow to significantly increase the rate of fire offered by HUNTER.

SHIMS

In HUNTER, correct adjustment of pinions is just as important as in the case of electric replicas. The only additional guideline is to ensure that upon shimming of the module supplied with the kit the slide surface corresponds to the maximum extent with the working surface of the core latch. The quality and accuracy of the adjustment will affect the functioning, power consumption and, in extreme cases, the possibility of damaging the unit.

MOTOR

Electric engine used for HUNTER is loaded to a negligible extent. Thus, the weakest engines, such as those installed in most replicas, are sufficient. But there may occur a situation where the brake will not be able to properly stop the pinions in the place designated by the cycle detector. This may result from using batteries with high voltage and power efficiency as well as using continuous fire mode where, after several seconds, the engine and gears are accelerated so that their stop requires using greater force. This problem may be solved by using an engine equipped with more powerful magnets. Producers of mosfets with cycle detection often recommend the use of HighTorque engines when using replicas with weaker springs. In this case HUNTER ought to be interpreted as a spring with extremely low rating and in compliance with the guidelines from the mosfet manufacturer.

BATTERY

HUNTER works with all types of batteries used to power AEG replicas. The suggested type of battery is LiPo. The nominal voltage should be 7.4V or 11.1V. It is also worth underlining that the choice of battery voltage translates into the rate of fire of the kit. With voltage of 7,4V the rate may amount to approximately 18-20 RPS, while in the case of 11.1V – approximately 25-28 RPS. The result depends on the applied power source, parameters and the condition of the electric motor as well as the quality of shimming and mosfet efficiency.

TAPPET PLATE/AIR NOZZLE

HUNTER uses the classic tappet and nozzles designed for AEG systems. The only necessary modification is to shorten the hitch of the tappet’s strip so that the nozzle can return to its free position during the contact between the gear and the core latch, at the latest. A detailed description of this operation can be found in the assembly instruction.

TRIGGER SWITCH/CUT-OFF LEVER/SELECTOR PLATE/WIRING

Due to the construction of HUNTER, electrical components and peripherals of the fire selector cannot be modified. One deviation from this rule is to adapt to the requirements from the manufacturer of the mosfet applied in the replica.

BEARINGS

The functioning of HUNTER does not burden the bearings even in the extent known from AEG platforms, so there are no special recommendations on this matter.

GAS SUPPLY FOR CONVERSION KIT

HUNTER kit is equipped with a supply hose with dimensions of 6/4 mm. It can be supplied only to the rear side of the replica, under the guide rail of the gunstock. It is not possible to enter it through the pistol grip. This is a result of leaving the electric engine and the pinions in place. Ways to lead the hose from the replica are described in the assembly instruction.

Do you have any questions?