- Check the orientation of the slide valve. I’ve installed this valve backwards a couple of times myself. Make sure the hexagonal end is closest to the launcher.
- Leak in the bike pump. When using a bike pump to pressurize the launcher, sometimes the foot/check valve in the bike pump or the hose or chuck will leak. This leak allows the pressure below the yellow QEV diaphragm (in Figure 2, step #8) to become lower than the pressure above the diaphragm and in the black pipe. This prevents the QEV from sealing properly. This is a rare occurrence, but we have added a ball check valve to the kits starting 4/2016
- Leaks in the slide valve assembly. Check for leaks and reseal per process 2. above.
Diaphragm within QEV sticks. Sometimes, when using a bike pump, the QEV diaphragm (in Figure 2, step #8) will fail to seal the outlet, and the air will leak out the launch tube with each pump, sometimes making the rocket slowly slide up and off the launch pipe. There is one super-easy trick that almost always works if the QEV diaphragm fails to seal. First, with the slide valve in the “Launch” position, complete one stroke on the bike pump. This will build up pressure in the hose of the bike pump. Next, slide the valve to the “Pressurize” position. The sudden inrush of pressure built up in the pump hose will almost always seat the QEV diaphragm. We have found that the more you launch, the more the diaphragm gets broken in. Now, pump up the chamber normally. Here’s a video showing the process: https://www.youtube.com/watch?v=rrQ52e9Pwwg&feature=youtu.be
QEV “honks” like in the video above, and the pressurized line trick demonstrated in the video doesn’t get it working. Sometimes, there can be debris that settles on the top sealing face of the QEV diaphragm. We have had a couple instances of some strings of teflon tape that have come loose and started to blow out of the system with each launch. The QEV is threaded together, and can be disassembled to check the diaphragm surface. Even though the QEV is new, it can still have a bit of debris in it from the factory causing it to not operate correctly. The QEV can be taken apart without removing it from the wood stand by following the directions below.
If needed you can take the QEV apart carefully and make sure it’s super clean inside. See pictures below for details:
1. So, you don’t need a vise to open the QEV. as you already have the launcher fully assembled, you can use the black pipe as a wrench when you unscrew the QEV. Angle the launch tube horizontal, so when you are loosening the cap, you are pushing downward toward the floor, like this using an adjustable wrench:
2. Or like this with pliers:
3. Once the cap is loose, it is usually easiest to unscrew it completely when the the orange tube disconnected. To disconnect the tube, push inward on the blue ring, which releases the teeth gripping the tube, then you can pull out on the orange tube. Once you have the cap removed, it looks like this:
4. You can now remove the diaphragm from the body of the valve and inspect the seat. It should look like this:
Check for anything across the surface of this inner gray circle.
5. I usually put the diaphragm in the removed cap, as it is somewhat greasy with petroleum jelly. Check the top flat face for debris, which may get stuck in the grease. This one is clean:
6. Reinstall the diaphragm in the body of the valve in the orientation shown below:
7. Next, check the seal between the QEV cap and the valve body. It’s a clear silicone ring, which can be difficult to see in the grease. It looks like this:
8. Now thread the cap back on to the body by hand. Loosen the wingnut and flip the launch tube to the opposite side of the launcher, and tighten the wing nut. Now you can tighten the cap while again pushing downward toward the floor. You can again use an adjustable wrench like this:
Or you can use pliers like this:
It’s super simple to connect your Air Rocket Launcher directly to an air compressor. Instead of attaching the Schrader valve/Check Valve to the “Launch” side of the slide valve, screw in a 1/4″ NPT Male Quick Connect Compressor Fitting. Set your compressor output pressure to about 100 psi. Slide valve back towards the compressor to launch and then forward towards the launcher recharge. Launcher will be ready immediately for the next launch.
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- Invite friends to see the launch of your rocket, loan your launcher to your local school or better yet, help a teacher do a launch day with their class.
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