The next stage in the parabolic solar collector thing is to have the fluid circulating. I want to have it run through the collector, then down a hose into a tub of water and then back. Measuring the heating rate of the water will give me a better value for the power.
For this, I clearly need a pump. And can I find a pump? Clearly not. For simplicity, I think I want one that has garden hose fittings on both ends. Sump pumps usually have that on one end, but the other end doesn't have any fitting at all. (Maybe I could disassemble one to find out, but I can't find any to do that with either.) I bought a drill pump for like $6 but it was too wimpy to be useful.
Not that it has to be that powerful. According to the back of my envelope, I only need about 60 gph in the worst case. Typical sump pump numbers are 10x that. I could probably do it myself by putting a squeezable diaphragm inline and stomping on it. What a lot of work, though.
But I have feelers out on craigslist and freecycle, so in the meantime how about something else? I know, I can try to make a much larger stirling. What'll I use for the piston? Oooh, brill idea: a cut off bike pump!
Take 2: And can I find a pump? Clearly not.
Maybe I'm just too cheap. Or maybe I haven't figured out the right workaround. Or maybe I'm asking for too much. All of these questions (plus a couple other things I'm stopped on but aren't worth describing) has my brain in vapor lock. I am unable to move on anything.