Adjusting the Spring Tension



You may find that you need to adjust the spring tension of the stager. This can be achieved by trimming the bottom of the FTC body and pushing it down against the bottle flange again. This will increase the spring tension. Trim a couple of mm at a time.



Notes



1. You may find that the dimensions of your FTC are such that the inner part of the quick connector does not move freely. You can apply a coat of silicone grease on the inside of the FTC body and the springs to help it move better. If this does not work you may need to get different FTC from another manufacturer.



2. Though the clear vinyl tubing says it is rated to 50psi, the actual burst pressure is a lot higher. It will easily handle 200psi+.



3. If you find that your nozzle does not lock properly into the stager, you can fix it by modifying the quick connector.



4. What if the sustainer is too light to keep the stager locked? See 'locking tab' below.



5. What if I can't get T8-FTC? - FTC is commonly available and can be ordered on line, but you could try making your own tubing by rolling up and gluing PET plastic together. As long as the dimensions of the tube are correct you don't need to use FTC.



6. In order to use this stager as shown here, you will need to construct the booster in such a way that it has a bottle neck at either end. This can be achieved either by splicing the bottles together or joining them with a Robinson coupling.



7. The sustainer will normally need to be supported with additional bracing to prevent the sustainer bending over and snapping the staging mechanism. This is normally required for most staging mechanisms anyway.



8. The stager could be damaged if the booster lands directly on it. The sustainer support can be used to protect the stager.



9. The springs you used should all be the same diameter so that when they are inside the FTC body they don't thread themselves into one another.



10. If you don't like the idea of using tape to attach the split FTC, you can try gluing it. Tape allows you to pull the stager apart if you need to.



11. If you find there is a tiny leak around the flexible tubing, it will likely stop once pressure is applied.





Using the Stager



To use the stager, simply fill the booster with water and place it on the launch pad. Fill the sustainer with water and push the sustainer nozzle into the stager and let the sustainer's weight lock the stager.



Locking tab



If the sustainer is not heavy enough, you can insert a locking tab in the space between the collar and the inner part of the quick connector. This is in the gap of the shorter piece of FTC. Tie this locking tab with a string to the launch pad. When the rocket launches, the locking tab will get pulled out, but acceleration will keep the sustainer in the locked position until the booster runs out of thrust.



The locking tab is just a small block of plastic or wood that is just thick enough to fit between the collar and the flange on the quick connector.



