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by Bill Mills
1998 saw the release of the Nova 700, a new paintgun from Air Star. Since its release this unique paintgun has been growing in popularity due to its all weather CO2 performance and simple maintenance requirements. Air Star has followed up by introducing new models, the Super Nova, and E.T. versions of the Super Nova and original Nova 700.
The Super Nova looks very similar to its predecessor. Both have cylindrical receivers with a shroud over their barrels. The Super Nova can immediately be identified by the shorter foam patting on its shroud, and porting near the muzzle. This feature is cosmetic, as the barrel remains unported. The Super Nova is also distinguished by a 45-style grip frame and bottom-line mounted regulator.
The regulator is angled slightly downward which prevents liquid CO2 from entering it by gravity separation. On the front of the regulator is an adjustment screw, covered by a vinyl dust cap. The adjustment screw sets the pressure for the guns operation. Speaking of which, the Nova series paintguns operate at only 95 psi, which is lower than every other paintgun on the market. While many may argue about pros and cons of low-pressure operation, it is definitely gentler on the paintball, and makes less noise. The other distinct advantage is that CO2 rarely gets below 95 psi, no matter how cold your tank is. This means that you don’t need an expensive compressed air system to use the Nova.
Low pressure also means large volumes of gas are used. Because of this the hose going from the gas-through 45 frame to the receiver is a macroline. The thicker size is necessary for high transfer rates. The low pressure also means that the line won’t overpressure. If you’ve ever been in the middle of a firefight and suddenly everyone on the field knew wear you were because of the “Psssssst!” of your microline blowing out, you can appreciate that.
On the Nova 700 the gas line fed into the grip frame. On the Super Nova it has been moved to the rear of the receiver. This change in placement seems minor at first glance, but makes a big difference in the holdability of the ‘gun. The hose does not get in the way as easily.
The rear of the receiver has also been changed. In the Nova 700 it contained the regulator and a simple expansion chamber. In the Super Nova, it is a large chamber that takes advantage of Dicer technology. To under stand Dicer, It’s important to understand how an expansion chamber works. An expansion chamber stabilizes gas pressure by evening out its temperature. The two key features of a good expansion chamber are a large amount of contact area between the metal and gas, and a large amount of metal to have stored heat to transfer (thermal capacitance). Rather than achieving this with conventional complex machining, the Dicer system is a simple approach. A large chamber is filled with metal beads. The gas flows through it with plenty of contact area for heat transfer, and there is plenty of metal to store heat.
From the Dicer chamber, air is routed two places, to the trigger frame, and also forward into the spool valve. The spool valve is what sets aside the Nova line of paintguns from all others. While most paintguns on the market are clones or modifications of earlier concepts, the Novas are based on a different valve structure, one that comes from industrial pneumatics.
The spool valve is a cylinder with a
disk at its rear. The disk fits inside the receiver and acts as a
ram. When air pressure is applied to either side, it can be moved
forward and back. Because it is designed with radial symmetry, all
of the wear surfaces are spread over 360 degrees. In industry, spool
valves have been well proven to require little maintenance.
The spool valve is the workhorse in the Nova, while a smaller pilot valve
in the trigger frame controls its position. The cylindrical portion
of the spool extends into an airspace called the accumulator. The
accumulator is sized to hold the amount of gas needed to fire one paintball.
Known as the ABS for short the Articulated Barrel System is another feature unique to the Nova paintguns. Rather than a bolt feeding each paintball and sealing the breech, the ABS includes a barrel that slides back and forth in a fixed shroud. The barrel moves forward under spring pressure to allow a ball to fall into the chamber. A small ring around the rear of the barrel seals to the interior of the receiver forming a pneumatic ram. When the spool valve is in the forward position, waiting to fire, the air pressure ducted from the accumulator feeds the ABS and pulls the barrel back around the ball, sealing the breech so that the Novas can fire from a closed breech position (closed bolt would be a bit of a misnomer since there is no bolt).
While there are minor components in the regulator and trigger assembly that move, the two key components that move during each firing cycle are the spool and the barrel.
When the sliding trigger on the Nova is pulled, it actuates the pilot valve inside the trigger frame. The pilot valve in turn moves the spool valve to its rear position. In the rear, the spool valve blocks the flow of gas into the accumulator, and at the same time opens the vent between the accumulator and the barrel. The gas in the accumulator then expands, propelling the paintball out of the barrel. Once the ball exits the barrel, the pressure inside the accumulator is depleted, and the air in the ABS can now escape out the barrel through the accumulator. With the air pressure relieved, the ABS spring moves the barrel forward to await the next ball.
The timing in the Nova design is unique. Most paintguns either have a bolt that is linked directly to the parts which actuate the valve, or the sequence of bolt movement and valve operation is handled mechanically or electronically. Any errors in this timing can result in gas blowback in the feed tube, or balls being chopped in half. The elegance of the solution Mike Wood designed for the Nova series is that it is feedback based. The barrel does not move forward until the paintball has left the muzzle, allowing the pressure in the accumulator to drop. Because of gas flow rates, the barrel stays forward long enough for a ball to drop into the breech without being chopped.
One of the first features we spotted on the Super Nova was the change in the feed port. The Nova 700 feed port is on the right hand side, angled at 45 degrees. The Super Nova feed port is vertical, for theoretically faster feeding and to keep the hopper behind cover when the player is leaning out to the right. When we asked Air Star’s Bruce Gillette about this, he said the change was made after the feedback we gave him when reviewing the Nova 700. Additionally, the Super Nova has a smaller trigger guard than the original Nova 700 design. The new trigger guard covers only the trigger area rather than the original cutlass design, which covered the entire hand area. The reason for this change is that trigger guards blocking trigger access from fingers on the grip will not be allowed by most paintball insurance companies in the near future.
E.T. fire Nova….
The Super Nova we were sent to review includes the new E.T. No, it’s not a little candy-stealing alien from a Steven Speilberg movie; the E.T. stands for electronic trigger.
Since a single pilot valve is what initiates the Nova’s firing sequence, conversion to electropneumatic operation should be simple. Since the timing is all in the spool valve, a simple switch and solenoid valve should do the job. Unfortunately, things are not always as easy as they seem, as Mike Wood found out when designing the E.T.
Conventional solenoid valves small enough to fit effectively in a paintgun could not move the volume of air needed to control the spool valve. Undaunted, Wood designed a solution. He used a compact Clippard solenoid valve to drive a bar that would actuate the valve in the trigger frame, in turn actuating the spool valve.
Following the radial symmetry in the rest of the Nova’s design, Wood built a trigger system that wraps around itself. The solenoid valve nestles neatly on the front of the trigger frame, protected by the aluminum block, which holds the trigger guard. It receives its air supply via air channels in the trigger frame. When actuated, it allows air pressure to drive a rod that is in the same position as the Nova’s normal trigger rod. This rod pushes on the pilot valve. With the rod in the way where does the trigger mount? On a metal sleeve that slides back and forth over the rod. In its rear position it contacts a microswitch.
Since all of the timing in the Novas is accomplished pneumatically, there is no need for fancy electronics to drive the E.T. A 3-position rocker switch in the 45 frame links the 9-volt battery to the solenoid and trigger. In its center position it is off, on safety. In the top position the E.T. Nova is ready to fire. The trigger switch is circuited straight to the solenoid. In the lower position, the result is the same as pulling the trigger and locking it in place with the mechanical safety. One shot is fired to clear the barrel, and the ABS is depressurized so that it may be removed for cleaning. A quick twist is all that it takes to remove the ABS from the receiver, one of the fastest barrel releases on the market.
The E.T. also includes a setscrew for the trigger. With the trigger guard and solenoid block removed, an allen screw sets the forward travel limit on the trigger. Dialed close back to the switch the trigger pull becomes minute. Players who like a fuller trigger travel can adjust it forward.
As with any paintgun, the bottom line is how it performs on the field. In an alignment of fates, we had field-tested the Nova 700 at Wayne Dollack’s Fool’s Gold scenario game. We took the E.T. Super Nova to that game’s sequel, Fool’s Gold 2.
We first put a 20-ounce CO2 tank on it, to check the trigger feel. Big difference with the E.T. The light microswitch makes it easy to crank out the paint. We handed it to Paul “Snake Eyes” Sanches of team MIB to try out. Paul was one of our field testers for the Nova 700, and his jaw dropped when he felt the new trigger.
At the chrono station, the Super Nova E.T. dialed in without problem. Using an agitated loader of course made a big difference. Since the Novas have little recoil we found the need to shake the ‘gun after every 3 or 4 shots if the loader was turned off. The Super Nova could handle heavy fire without freezing up, stuttering or dropping velocity. The tank and regulator got icy to the touch, but the Dicer technology kept it going.
Chris Willie was the first to hit the field with the new gun, and unfortunately, it came back in with a problem. The trigger is locked into its sleeve by a setscrew, and ours had slipped. No problem, we just tightened it back down.
There was another problem. When we locked the trigger back down we had let it slide to the rear of its sleeve, which is thin walled. When we tightened it down, it crushed the sleeve in, locking it to the actuating rod. The Nova fired, not because of the solenoid system but because we had inadvertently converted it back to a manual trigger. It just didn’t have that super feel that it had before.
Once we got the E.T. Super Nova on the workbench to check it out, we realized our flaw. A little airsmith work and we’d repaired the trigger sleeve. The rate of fire was back. We spoke to Mike Wood about the problem, and he explained that there were some last minute adjustments made before sending this particular ‘gun for testing, so it did not get all the usual checks and double-checks of one that goes through the normal production line. With the trigger back together, we found the performance we expected. The high rate of fire, accuracy, and velocity stability were all still there.
So with a new generation of Novas shipping from Air Star, we asked Mike what was next. Even though the E.T. doesn’t require electronic circuits, he’s already designed a multi-function controller board to allow select fire/burst and other modes, but it waiting for further paintball industry and insurance company decisions about what firing methods are considered the most safe and responsible.
Novas 700s are appearing more frequently
on fields around the country, and with the Super Nova in paintball stores,
and availability of Electronic Trigger for both versions, they will continue
to grow in popularity. The Nova line is distributed exclusively by
Paintball Supply in South Carolina, and dealers may contact them for
more information, or see Air Star's web site at www.nova700.com.
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