Air Star Nova FAQ
V1.00 By Bill Mills All content, except where noted, Copyright 1999. All rights reserved.
The Nova series paintguns are produced by Air Star, and distributed by National Paintball Supply. They were designed by paintball player and pneumatics design engineer Mike Wood. Prior to an interest in paintball, Wood patented a number of inventions, including the CO2 powered T-Shooter that is used at sporting events to launch hot-dogs and T-shirt to audiences.
What models are available?
Air Star produced the original Nova 700, the second generation Super Nova, and Electronic Trigger (ET) versions. The 700 can be easily identified when compared with the SuperNova by several distinguishing features:
45 degree feed port
"Heavenly Body" color fade anodizing
Top center mounted sight rail
Vertical feed port
Angled sight rail
Bottom Line mounted regulator
What Features make the Novas unique from other paintguns?
The Nova paintguns operate at a very low pressure - 95 psi, and instead of a bolt, they feature an Articulate Barrel System (ABS), the barrel moves back around the ball, sealing the breech. The internal components of the Novas are pneumatically actuated (there is no hammer) and are radially symmetrical, which in conjunction with the low pressure means the internal seals have a long service life. The low pressure requirement also means that CO2 is an excellent power source, since regardless of amount of shooting, or outside temperature, a CO2 tank rarely delivers less than 95 psi gas pressure.
How do the Novas work?
The gas entering a Nova first goes through a pressure regulator that is adjusted to output around 95 psi. In the Nova 700, the regulator is mounted in the rear of the receiver on the central axis, in the Super Nova, it is mounted in a bottom-line, with a macroline hose leading up to the rear of the receiver. From the rear section of the receiver the air is routed into two places. One path supplies gas to the spool valve, while the other feeds the pilot valve. The spool valve is the Nova's main valve, controlling the gas used to move the articulated barrel, and to fire the paintball. The pilot valve is a small 4 way valve located inside the trigger frame. The trigger is held on a rod, which slides forward and back in the frame, when pulled back, it actuates the pilot valve. The gas through the pilot valve then moves the spool valve from the rest position to the firing position. When the spool valve is at rest its front is blocking the connector passage to the breech. This allows a full 95 psi charge to build up in the airspace known as the accumulator. 4 gas ports lead from the accumulator, around the breech area to the front of the receiver. When the accumulator is charged, gas pressure through these ports pushes the articulated barrel to its rear position, sealing the breech. When the trigger is pulled, the pilot valve actuates the spool valve. The spool valve moves rearward. In the rear position it cuts off the gas flowing into the accumulator, and allows the gas in the accumulator to rush out into the breech, firing the paintball. Once the paintball has left the barrel, the pressure in the accumulator drops to the point that the gas pressure holding the articulated barrel back is overcome by the barrel spring, and the barrel moves forward. This opens the breech and allows the next ball to feed. This gas pressure feedback system assures that the barrel will not move until the ball has been fired, preventing barrel movement from causing accuracy problems.
How do you field strip the Novas?
The Novas are amongst the fastest and easiest paintguns to field strip. In its normal rest state, gas pressure holds the articulated barrel system shut, and prevents its removal. Pulling the trigger back, and locking the safety (or switching the safety switch to constant-on in the case of the ET models) fires one shot, clearing the breech, and depressurizes the ABS. With a very slight twist (about 1/16 of a turn) the ABS is unlocked, then removed with a pull. This provides full breech and barrel access for cleaning. Further disassembly of the Novas is a bit complex to be done in the field, and is best done in a workshop (bench stripping). Opening the receiver to remove the spool valve components, and even removing the trigger frame from the receiver is a not a task for the casual user, and is best left Air Star service techs. Fortunately, due to the simplicity of the Nova's internal structure, and to the low wear caused by low pressure operation, bench stripping a Nova should never be required. For airsmiths who do decide to bench-strip a Nova based paintgun, construction of appropriate press tools to remove internal components is important. Uneven force applied to the delrin components can cause deal damage and valve damage.
How does the ET work?
As with all electropneumatic paintball guns, an electrical current activates a solenoid (a magnetic coil that pulls or pushes a rod to cause mechanical movement) to control the movement of gas. Electropneumatic control has become fashionable in paintball because of the very short and light trigger pulls possible with an electronic switch. The Nova's designer, Mike Wood found that solenoid valves large enough to replace the 4 way trigger valve of the Nova were to bulky, and required too much power to be practical. Instead he chose a light, compact Clippard solenoid valve to actuate the 4 way valve. The ET Novas feature a slightly different trigger frame than the normal Nova 700 and SuperNova. A third gas channel routes gas to a solenoid valve in the front of the frame. The trigger rod is replaced with a slightly narrower rod. When the solenoid valve is actuated it applies pressure on a small 6 mm wide pneumatic ram. The ram pushes the link rod causing it to actuate the 4 way pilot valve. Since the link rod is placed where the trigger rod sits normally, the trigger rod is replaced with an aluminum sleeve that slides back and forth on the link rod. A return spring keeps it forward at rest. At the rear of its stroke it contacts and actuates a microswitch that is wired to the 9 volt battery inside the .45 frame, the safety and the solenoid. Because the timing of the Novas is handled with gas pressure, there is no need for electronic control circuits. The safety switch has 3 positions. Off - will not fire. On - will fire when the trigger is pulled. Constant on - fires and holds the breech open to allow articulated barrel system to be removed, this is the same as pulling the trigger and locking the safety on a mechanical trigger Nova. The Electronic Trigger can be adjusted to a pull length of less than 0.5mm.
What is Dicer technology?
The Super Novas feature Dicer technology. The rear of their receiver is filled with unevenly shaped aluminum alloy pellets. There is a direct relation between the pressure and temperature of a gas and the volume of the space which it occupies. When one of these variables changes, the other two are affected. With CO2 these changes are especially great, and can cause problems in paintgun performance. One approach to help stabilize the pressure of a gas that has just undergone change is to stabilize its temperature. Expansion chambers allow the temperature of a gas to balance with the ambient temperature by absorbing heat from the metal walls and internal fins if there are any. The two keys of a successful expansion chamber are that it have a large amount of metal to store and transfer heat, and that it have a lot of surface area to contact the gas. The Dicer beads have both, as the gas flows through the airspaces between the beads.
Weren't the Novas recalled?
Yes and no. Some of the Novas were recalled. About 200 Nova 700s were recalled with a safety concern. The recalled Nova 700s can be identified by serial numbers 991 1500 through 991 1787. Additionally, any Nova 700s with lower serial numbers that had been returned to Air Star for maintenance may have had the newer regulator installed, and are affected by the recall. The reason for the recall is that with a change in regulator design there is a potential for failure in an overpressure relief valve. If the regulator fails and overpressurizes, and the relief valve fails, and a person (as one did) is using the paintgun in a partially disassembled state (has the sight rail screw, which locks some of the internal components in place removed), it is possible for the pressure to force the regulator body out the back of the gun. While this failure has only happened in one case which did not result in injury, Air Star has chosen to recall the affected Nova 700s even though the failure requires operator error (removing a vital screw) to occur. For complete recall information, see the Air Star web site.
What are some common misconceptions about the Novas?
* The Novas have all been recalled because they blow up. - FALSE, see above.
* The Novas have only one moving part. - FALSE, the Novas have several moving parts. The articulated barrel, trigger, trigger rod, pilot valve, spool valve, regulator piston, and regulator pin all move. Additionally in the ET models the link rod, link rod piston, and solenoid core all move as well.
* The Nova does not contain a 3 way valve. - This is really a matter of semantics. An Autococker does not contain a 3 way valve either. What is typically called a 3 way valve in the Autococker is called a 4 way valve in the pneumatics industry because it has one input, two outputs, and two exhaust ports. Like the Autococker, the Novas contain a 4 way valve.
* Nothing on the Novas can be upgraded. - FALSE There are a number of alternative barrels available both manufactured by Air Star, and National Paintball Supply under the Pro Line name. The grip frame is attached by an M16 style lug offering a number of grip options, various sights and stocks may also be added.
* Novas have a problem with freezing up on CO2. - FALSE The Novas have excellent CO2 performance. It is not uncommon for water to condense and freeze on the tank and rear of the receiver, or bottom-line regulator when rapid firing CO2 in humid weather. This is because the gas is drawing heat from the metal, and it does not indicate a freeze-up or failure of any of the internal components.
* Novas don't work right on compressed air. - FALSE Novas work just fine on compressed air. However due to their excellent CO2 operation, the chief advantage to using compressed air is that compressed air systems have a tank pressure gauge which indicated how full the tank is.
* Novas are inherently inaccurate because the barrel moves when they fire. - FALSE The barrel is fixed when a Nova fires, and does not move until the ball has left the barrel depresurizing the accumulator.
* The Nova 700 was the first paintgun to feature a moving barrel and the first to not have a bolt. FALSE The NSG Splatmaster featured a moving barrel, neither the 3357 Spotmarker, or the SMG-60 had a bolt.
What comes with the Nova and what do I need to add to make it usable?
The Novas ship with the a barrel plug, instruction manual, appropriate sized hex wrenches, and in the case of the ET versions, a 9 volt battery. Before hitting the field, they need a loader, CO2 tank or compressed air system, and an elbow for the Nova 700s. The neck of a normal loader can slide over the vertical feed port of a Super Nova, and can be secured with a hose clamp, or electrical tape. While a plain loader will work, an agitating loader such as the Viewloader Revolution greatly reduces the risk of a ball break caused by the ABS closing before a ball has fallen completely into the breech.