Wednesday, September 19, 2007

Early Dual Burn Motor Test

This is a video of a static test that I conducted back in 2005 when I first got involved with the Sugar Shot project. The dual burn concept is not new, but I haven't heard of any amateurs pursuing it. At this size, I don't think you'd realize much benefit. However, in a slightly larger motor, such as the one that we are currently constructing, you begin to see some real benefits. The concept is similar to staging, but in some ways simpler to execute. One of the major difficulties is that the first half of the casing and the nozzle are subjected to twice the heating that they would have to endure in a two stage design. The motor that we are currently working on has the potential to reach nearly 50,000 feet, which is considerably higher than you would expect to go with a "standard" motor that expends all of it propellant close to the ground in denser air. Despite some minor problems, I considered this early test to be successful. The o-ring on the upper bulkhead was damaged, and I didn't have a replacement. That resulted in a small leak during the 2nd burn. However, there were several key things that did seem to work. Most notably:
The first propellant grain burned properly and ignited the epoxy plug .

The epoxy plug burned through without igniting the second propellant grain.
The burnt remains of the epoxy plug did not obstruct the nozzle.
The mid-bulkhead did not seem to have a significant effect on the 2nd phase thrust.

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