Project
1115 Static tests

Results

• Four identical engines were static tested with epoxy / Kno3 nozzles. Each engine produced a pressure graph and fired with no problems. The main difference between this set of tests and the 1108 tests was a small structural modification to strengthen the nozzle assembly and a reduction of fuel in the engine by 1 inch or 5% of the total. The purpose behind the fuel reduction was to create a more comfortable buffer between the PVC rupture pressure and the chamber pressure to increase engine reliability.
• All engines fired perfectly and the nozzles produced smoke for 12 seconds after engine burn out. The main problem noted was a reduction in overall thrust. With a Pourstone nozzle and a .7" throat, 140 lbs. of peak thrust was common. With the epoxy / Kno3 nozzle and a .7" throat, only 75 lbs. of peak thrust was achieved. Of course, the overall fuel amount had been reduced by 5% but I believe the major contributor of the loss to be the epoxy / Kno3 nozzle's excessive erosion. Unfortunately, there was no way to tell how much nozzle eroded because the nozzle burns completely after the engine cuts out.
• Even with the nozzle erosion, all engines came in as solid J's.
• This was also the November launch for the San Diego Rocket Society. James Grover from Grover Aerospace was there and launched three rockets with a variaty of engines.

• Click on graphs to view pressure curves.

• Static 01 - 985 Newton seconds.
• Static 02 - 1093 Newton seconds.
• Static 03 - 1160 Newton seconds.
• Static 04 - 1039 Newton seconds.

Construction

• Engines had a 2" PVC nozzle section 3.25" long and a 2" PVC fuel section 19.5" long. Each engine had a 2" PVC cap on the forward section of the engine. Nozzles were made from West Systems Epoxy and Kno3 to a 35/65 ratio. Nozzle throat was .75" long and .7" in diameter.

Pros

• I'm sure this design is very reliable.
• Inexpensive.
• Easy to construct.
• Easy source of smoke that is self igniting.
• Engine igniters worked perfectly.

Cons

• HUGE reduction in overall performance. Only 75 lbs. of peak thrust for a 5.5 lb. engine. I'd like to see at least 100 lbs.

Pictures

• Nozzle molds and PVC nozzle retaining sections.
• PVC nozzle retaining sections showing shoulders to hold in epoxy nozzle.
• A view of the small convergent section and the divergent section of the nozzles.
• Close up of the divergent cone.
• James Grover's first flight with an AP J300.
• Static 01 sequence showing transition to smoke.
• Static 02 sequence showing transition to smoke.
• James Grover's second flight with an L600.
• Static 03 sequence showing transition to smoke.
• Static 04 sequence showing transition to smoke.
• James Grover's third flight with an L1300.
• We found this spent military flechette rocket in the desert.
• Markings on the side of the engine.
• Markings on the side of the warhead section.
• Check out these kick-ass spring loaded fins.
• Rifled nozzle to spin the exhaust. Sweet.

Video

• Static test 01 pressure reading.
• Static test 02 pressure reading.
• Static test 03 pressure reading.
• Static test 04 pressure reading.
• James' first flight.
• James' second flight.
• James' third flight.

CAD Drawings

• 1115 engine design - .dwg file.
• 1115 engine design - .pdf file.

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