• Same as before, cheap and simple to make
• Simple to re-use with minimal prep and limited number of parts required (i.e. no o-rings and liners etc.)

Construction Results:

New lightweight nozzle with longer divergent cone. All aluminum construction as 50+ tests of previous aluminum nozzle show no wear with bates grain. The forward closure seen above is a separate delay chamber which eliminates the need for o-rings and washers.

This is what it looks like before assembly. In order from left to right: 

• Forward delay chamber with ejection charge holder- The ejection charge is held in place with a little ball of wadding
• Ejection delay- The grain is made with the rolling technique but the key to its success was suggested by a fellow Arocket list member. He suggested wrapping the delay in kraft paper and epoxy. This provides a durable delay insulator that holds up well for the entire delay burn.
• Delay Closure- threaded inside and out, this compresses the epoxy/kraft paper roll of the delay element and eliminates the need for any additional sealing features such as o-rings etc. A small hole in the aft end allows the delay grain to ignite.
• Grain- Same rolling technique as before, but am now using Dextrose (http://www.nakka-rocketry.net/) with the KNO3 since it is easier to work with than sucrose. This is shown wrapped in a wood glue/Kraft paper liner but I think I will start using the epoxy in the future since I am doing it for the delay element now anyway.
• Casing- Same 1/2 inch aluminum tube with .049 inch wall. 7/16 thread on the inside of both ends using a tap.
• Nozzle- Turned on drill press with new "loose bed" technique. I clamp a cutting tool to the drill press bed, put the part in the chuck and lightly push the loosened bed into the part. This allows me to create the angle and even round shapes as well. New technique for threading these parts is to place the die on the drill press bed while the part is still in the chuck. I then hand rotate the chuck while putting a little downward pressure. This insures a perfectly straight thread. Also doing it with the tap for the casing to insure it starts properly.

Closeup of the nozzle, OK I am pretty proud of this particular piece!

Of course, now I have an even better one found here!

Conclusion:

I ended up with a lightweight motor that has a consistent delay element. Delay time will be modified as necessary by drilling a hole into it to the required depth. Now that the delay element is working consistently, it is time to put it in a rocket! I will post the results here later.

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