Sunday, 17 July 2011
I have been sick with a cold for the last few days so haven't been able to do much. Saying that I finished sealing all the plumbing and started pressure testing. When i first pressurised the system there were a few leaks, which i had been expecting. They were all due to not tightening the respective fitting after the mock up. I did have an issue with the fill solenoid leaking. This was because solenoid valves only hold pressure in one direction, and when filled (with no fill pressure on the other side) there is a big pressure difference. I fixed the problem by adding a check valve to the outlet to the no gas can flow back through the valve. It still leaked a little but i think this is because there was not sufficient pressure in the system for the check valve to be completely engaged. I also had a more concerning issue with the main pressurisation solenoid leaking. I took the solenoid apart and found a small metal shaving logged in the solenoids teflon seal. I pried it out but the valve still leaks. Its hard to tell if it leaks any less because its is a little leak. I will try smoothing out the seal as there might still be a small gap. I dont really know how the metal bit got there as it was a new solenoid and all i did was plum it into the argon tank. If that tiny fragment of metal of which i have no clue of its origion did that much damage i am concerned what the manny more fragments i know are in the run tanks will do to the drain solenoid. I started to fill the nitrous tanks with water but then the batteries in the relay box flattened to the point where i couldn't operate two solenoids at once. I also had a few issues with the wireless system. The first problem was that when i tried to toggle some of the relays too quickly the commands the controller was receiving got out of sync. This usually only happens when I send a malformed command (for example f01 instead of f001). I believe I reached the limit at which the xbees could communicate so they were dropping characters. Because of this i really need to rewrite the command that is sent. I was thinking of either adding a checksum or a terminating character. A checksum would be more robust but it will be difficult to implement unless the ardwino has a checksum library. I also had a wired problem where the xbee would not connect in the workshop but was working fine in the study. It seemed to fix itself eventually but was concerning that i couldn't identify any problem. So anyway i will wash out the tanks next chance I get then i can mount the engine and flow test the injectors. I am think that the first test I run will be a few second run with no instrumentation. I haven't done any work of the sensors yet but am keen to have a test fireing soon, so the first test will likely be without any sensors. I am not expecting the first test to go perfectly and there will likely be a few issues I discover when live firing.