Brief:
About four years ago I got a WRC2 for a student rocketry contest. I've since flown it six times, most recently just a month ago, and it has worked perfectly each time. It's a real kick to be able to push a button and watch your rocket respond by kicking out the main parachute.

Details: The WRC2 receiver (the onboard part) is quite large. I put mine in a 5.5" diameter rocket, and at 3.25" across (and fairly tall), it'd be a very tight fit in a 4" tube, though you might make it work. The fact that it's so large makes it mostly impractical as an upper stage ignition device (most upper stages are less than 4" diameter). It might make a nice airstart initiator, though.

Construction:

The WRC2 receiver requires 11-14 volts. I see in the first review that Al rigged a 12v supply. I wrote to Jim Amos (the maker) for advice, and he told me that people generally used a 9v in series with a pair of AA cells, so that's what I used. It looks ugly, but it works. If I'd known then what I know now, I might have gone with something more like Al's more elegant setup.

Setting up and using the unit is pretty straightforward. There are standard screw terminals for the power supply, an on/off switch, and for two outputs. The outputs can be used for a variety of purposes. I have them connected to my deployment charges (more later). When powered up, the receiver beeps continuity for the output terminals, just like an altimeter does. The transmitter is a small plastic box with a removable lid. You need to install the battery shortly before use - there is no on/off switch for the transmitter. My only complaint about the unit is that it is difficult to have to keep inserting and removing the batteries, and since there are wires from the box to the lid (which holds the pushbuttons), I'm concerned about the constant stress to the wiring. An on/off switch would be a nice addition. No problems so far, though.

Finishing:
The first unit that I received was apparently defective. After much fiddling, I could eventually get it to work, but only if the transmitter was right next to the receiver, and on the right side of the board. I asked Jim Amos about it, and after verifying that I had it set up correctly, he quickly and easily replaced the unit with a working one. I have great confidence in Missileworks products and service.

When I got the replacement, I tested it the same way I did with the first unit. I attached a couple of LEDs with a resistor on one leg to the output terminals of the WRC. Then power up the transmitter, pressing the reset button on the circuit board before closing the lid (per the directions), and then the receiver. Press button one, and watch the corresponding LED light. Press button two, and watch that LED come on. I did some range testing on the ground, and had good contact out to quite a long distance. I've never had an out or range problem (though I've only flown the thing to 3300 feet).

Construction Rating: 5 out of 5

Flight:
I used mine in conjunction with a standard altimeter. The altimeter was the primary device for apogee deployment, with output one of the WRC2 used for a backup apogee charge. The WRC2 was the primary device for main deployment, with the altimeter set to back that up at a low altitude. In no case did I need the backup charges - both the altimeter and the WRC2 fired their charges properly on all six of my flights. Once the altimeter blew the apogee charge, I waited until an appropriate altitude, and then pushed button two to fire the main charge. Once the main was properly deployed, I fired the backup apogee charge on channel one to avoid landing with live deployment charges. I could have fired the backup apogee charge as soon as the primary apogee charge had blown, but I did not, because that would risk knocking the main parachute out while still up near apogee. I strongly recommend using this sequence of events when using a radio control in conjunction with an altimeter for deployment.

Flight Rating: 5 out of 5

Summary:
Overall, I'm very pleased with the WRC2. They're out of production, but there must be quite a few of them floating around out there - if you can pick one up, it's worth it. There's a rumor that Jim Amos plans to release a newer model. If there were a smaller version, I'd buy it immediately and use it in my day-to-day rockets. Unfortunately, the size of the WRC2 means it's really only practical in large rocket. I'd love to see a smaller version (and put an on/off switch on the transmitter box, please). I love flying the thing - it's really really fun to push that button and pop your main chute on command.

Overall Rating: 4 out of 5

Other:
One surprise about the unit is that the two buttons/outputs are not the same. Button one/output one works as you'd expect it to: you push the button, and a second or two later, output one becomes energized. Release the button, and it turns off again. Button two/output two works differently. When you push the button, the output becomes energized, and it latches on, which means that it remains energized until you either power down the unit, or press the reset button on the receiver (the part that's in the rocket). You cannot (as far as I know) turn off output two from the ground once you've turned it on. In addition, according to the manual, if the unit goes out of range, after an hour of no contact with the transmitter, output two will energize on its own. I've not tested that function. Both the latch and the out-of-range feature are designed to make the unit more useful for activating tracking devices. None of that interferes with the use of the unit for deployment.