My hyrbid will NOT fire
Posted: Thu Oct 25, 2012 10:26 pm
Im absolutelly 100% positive Im fueling this thing correctly. I built a VERY large PVC hybrid.
I have a slightly odd shaped chamber (lots of steps) so I filled the cannon chamber with water all the way to the burst disk and it came out to be 408 cubic inches (6700CC/ML) I built a volumetric propane log with a matching pressure gauge to the one on the launcher. It happened to be 3.57 Cubic inch (58cc) from the first cutoff valve to the male air fitting. 100/95.8=1.0438 or 4.38 CC fuel per 100 CC chamber im told is optimal or stoich for propane. 67 (100)cc is my chamber so I need 67(4.38cc) fuel or 293.46 cc. Since my fuel meter came out to 58 CC I need 293.48/58=5.05 bar of propane in my meter. 5.05 * 14.7 = 74.235 PSI absolute or -14.7 to read ~ 60 psi on my gauge....
I finished these calculations, screwed the cap on my chamber, installed a burst disk of Nashua aluminum Foil Insulation tape. Put 60psi in my fuel meter and filled the cannon with the 1x charge... Boom ... 4 times with 100% reliability... Next I pressurized my log to 60 PSI fueled the cannon, repeated again for 2x. Charged the Cannon to 1 bar on the same brand/type of gauge I used on the meter.... Nothing. no light no anything. I tried pumping more air in up to 30 PSI with the same fuel and it still wouldnt light. I started letting air out and held down the trigger while doing so and One time as a fluke in lit, it was so spectacular to launch a 3 oz slug of potato at 500 Miles per hour into a tree! I didnt know a potato could cut wood like an axe!... However, the celebration didnt last... after a dozen attempts I can not get this thing to light. any ideas folks?
I have a slightly odd shaped chamber (lots of steps) so I filled the cannon chamber with water all the way to the burst disk and it came out to be 408 cubic inches (6700CC/ML) I built a volumetric propane log with a matching pressure gauge to the one on the launcher. It happened to be 3.57 Cubic inch (58cc) from the first cutoff valve to the male air fitting. 100/95.8=1.0438 or 4.38 CC fuel per 100 CC chamber im told is optimal or stoich for propane. 67 (100)cc is my chamber so I need 67(4.38cc) fuel or 293.46 cc. Since my fuel meter came out to 58 CC I need 293.48/58=5.05 bar of propane in my meter. 5.05 * 14.7 = 74.235 PSI absolute or -14.7 to read ~ 60 psi on my gauge....
I finished these calculations, screwed the cap on my chamber, installed a burst disk of Nashua aluminum Foil Insulation tape. Put 60psi in my fuel meter and filled the cannon with the 1x charge... Boom ... 4 times with 100% reliability... Next I pressurized my log to 60 PSI fueled the cannon, repeated again for 2x. Charged the Cannon to 1 bar on the same brand/type of gauge I used on the meter.... Nothing. no light no anything. I tried pumping more air in up to 30 PSI with the same fuel and it still wouldnt light. I started letting air out and held down the trigger while doing so and One time as a fluke in lit, it was so spectacular to launch a 3 oz slug of potato at 500 Miles per hour into a tree! I didnt know a potato could cut wood like an axe!... However, the celebration didnt last... after a dozen attempts I can not get this thing to light. any ideas folks?