Quick & Easy Whistle Rockets
This is a simple project that requires very little tooling. It does involve whistle fuel, so it should still be done carefully and with appropriate precautions. The whistle fuel I use consists of 76 parts potassium perchlorate, 23 parts sodium salicylate, 3 parts petroleum jelly, and 1 part red iron oxide. The petroleum jelly is incorporated into the mix with Coleman fuel. The details for making the mix can be found at Passfire.com. You can also add 1 part titanium after the fuel is prepared if you want a spark tail (I used 10-30 mesh spherical). Keep in mind that the titanium makes the fuel more sensitive, so handle it carefully.
These rockets are based on the whistle inserts from Bill Ofca's Technique in Fire, Volume 6, "The 4 Inch Color, Whistle and Report Aerial Shell." The tubes are 3/8 inch ID, 9/16 inch OD, and 3½ inches long. To begin, I ram a plug of ¼ teaspoon of bentonite clay. This is consolidated with 6-7 blows from a deadblow hammer. You'll notice the end of the tube flare out a bit. Ofca's loading technique for the whistle mix is different from most rockets or fountains, but it makes the process pretty simple. I pour about 1 teaspoon of whistle mix into a funnel. I use a bamboo skewer to help push the fuel into the tube. The tube is simply filled to the top in this manner, then I consolidate it with hand pressure only. This process is repeated once more, then the entire amount is pressed firm. I use a one ton arbor press. The tube should be just past halfway full.
The finished tube is now attached to a stick. I use 1/8 inch dowel rods cut to 18 inches. The stick is placed just far enough up the side of the tube to fit 2 wraps of tape. I use ¾ inch nylon strapping tape. All that's left is the fuse. I use a 3-4 inch piece of visco placed into the tube so the end rests against the fuel. This is then securely taped to the stick so it doesn't drop out as it burns. I launch mine from a section of ½ inch CPVC pipe. The rocket takes off a little slow, but accelerates quickly and flies to about 150 feet. The particular pressing technique for these rockets causes them to finish their flight with a nice salute.
