Ben wrote:Hey, congrats on the sucessful run. The L:D is a bit unfavorable, but it is always nice to verify that a design is sound. As I mentioned in e-mail, and as Mark implies, you may be doing yourself a disservice with propane. I take some responsibility for encouraging you to get a propane setup.
Thanks. I knew it had to be sustainable, somehow, and the success with the Elektra I by lengthening it was the best indicator of what was likely to work. It's interesting how the smoothness of the design as a whole works out with the numbers. My first grab at the Reynst point at L/8 was apparently perfect for the Lady; on the Elektra I it turned out to be L/12; and on the Elektra II it is almost exactly L/10, right in the middle. You could make a schedule of Reynst engines on that basis, I guess, like a sort of Catalog of Design Geometries, for whatever good that would do you. That's one thing I love about this sport; you learn something new just about every time out. The bad thing about it is there is a lot of failure between successes. But, of course, that sweetens the success when you find it.
The only reason I decided to go with propane is it's a vapor fuel you can get refilled anywhere. The use of vapor fuel, of course, has one sterling advantage: You don't have to design a carburetor at the same time you're trying to work out the design for your jet (the remaining option, spraying pressurized fuel in through the wall of the chamber of a pulsejet, is too unsavory to me to merit further consideration ;-). Thus, you isolate two sets of variables so they can be worked on [more or less] independently. Of course, there are better vapor fuels, but none as accessible as propane, and none that are both better and cheaper, that I know of.