|| Mark |
| Date :
|| 2002-01-24 19:19:21
| Subject :
|| Re:Mini Myers Initial Tests comment and digression
Larry Cottrill wrote :
>There is certainly nothing wrong with seemingly 'crude' construction materials and methods for experimental purposes. If I had no welding skills and just wanted to make noise, threaded pipe would be an ideal material -- for the mini spark plugs I use, you wouldn't even need to build up a mount, just drill a 7/32 inch hole and thread it with the tap! Couldn't be simpler. I think the conduit is perfect for my skill set (you do have to watch those fumes while welding, of course!). What would really be nice would be to have a good collection of scrap lengths of chrome-moly aircraft steel in various sizes. Sometimes, the ideal thing would be double-butted Reynolds bicycle tubing (also basically chrome-moly). Chrome-moly is the most weldable material on earth, hands down. I like using pieces of spent 12.5 gram CO2 cylinders (also high-strength steel) - the 'neck end' is a wonderful, smooth nozzle that you can trim back to any area ratio you want, though of course you don't always get the 'ideal' shape you're after, in every case.
>I don't think I've ever lost anything meaningful by building small in terms of learning from the experiments. My only continuing gripe is not getting anything to run without constantly piping air in -- if you want pressure-driven constant-burn liquid-fuel combustors, I'm your man! Yeah, things would probably be more successful on a larger scale, but on the other hand, if I do get something workable, scaling up will be a shoo-in. Building small means minimal tools (I have no shop of my own -- my little bench vise isn't even bolted down to anything!) and minimum lineal inches of weld to get something built. But, those aren't the only reasons to think small, and that relates to your DynaJet tale of woe:
I agree with the premise of small, the little jets I built were astronomically hard to get to run. I couldn't decide if it was starting and stopping because of too much or too little fuel or the valve or some or a combination of variables to get me in the ballpark. Once you have put up with untold frustration and months of pondering, a normal sized pulsejet is like moving from a really hard school to a really easy school. Little puslejets are nice though, and anyone can find scrap stuff to experiement with. I also tapped and threaded my spark plugs and that is not very hard for anyone to do.
I tell you though, you could sit endlessly thinking, but the good stuff often comes out of experimentation. And too, experimentation can be fun so don't deprive yourself of all that fun and HARD WORK.
This is not to say you shoudn't think about something before trying it, you could really have a bad day of failures, but there is no subsitute for experimentation.