Dan Hopper - a brief bio

I asked Dan to tell me a bit about himself, and he responded with this in an email. -Hal

What to say about me?

Well, back in my younger days (in the late 60's and early 70's) , I built and drove race cars on local dirt and paved tracks. I would notch tubing (black pipe usually) by cutting it at an angle on a band saw and noticed that if I cut it at just the right angle, it would fit pretty well. One of the best metal fabricators I knew told me that the secret to getting a good weld was to get a good fit. All the time I was watching that saw cut, I kept thinking that there must be a mathematical formula for doing this. When a person is busy with racing he just doesn't have time for such trivia, though. While still racing, I started college and eventually earned degrees in Electrical Engineering Technology and also in Business Management. I took all the math courses I could because I found math easy, interesting and useful.

About fifteen years ago, I developed an early version of TUBEFIT. The first versions of it ran on the Radio Shack Color Computer interfaced to a very old HP Plotter.

About 4 years ago I retired from the engineering profession, and built an airplane. It is a Vans RV-7A. Search for Vans Aircraft on the web. My wife and I fly it all over the country and really enjoy it. It is a fast cross country cruiser, and a fun aerobatic airplane also. My interest in airplanes caused me to revisit (and refine) TUBEFIT, in order to possibly build another airplane using 4130 tubing for the fuselage this time.

When I came across this web site, and saw Hal's program that made templates very similar to mine, I asked him some questions about how I could make TUBEFIT print on a modern printer so that other people could benefit from all my efforts. He suggested using PostScript, and sent me some sample files to help me understand how to do it. Hal also offered to post it on this site. If you download and run TUBEFIT you will need a printer that will handle PS files. I think that most of today's printers will do that.

TUBEFIT the program, as of now, is still somewhat primitive, and was developed in a DOS environment. FORTH is the only PC language that I know how to write this program in, so don't ask me to rewrite it in C++ or Visual Basic, etc. Hal has posted the derivation of the algorithm on this web site, and for you programmers out there, please have at it. I would only ask that you give me credit for the basic algorithm if you publish it. If you sell it or use it for commercial purposes, that's another matter.

If you want to use TUBEFIT, please look over the derivation to help you know how it should be used. There are some comments about why the reference lines are there as well as how to cut the tubes.