news5.htm
This page will include progress reports, notes, random brain farts, and other ramblings.
The near flight weight engine is now ready for testing. It weighs just under 2 lbm and I hope to get about 8 lbf thrust at 120 mph airspeed. We'll find out.
Six parts now make up this engine. The flame holder is flanked by the aft-body and the fore-body. In front are the inlet cone (subsonic) and the two fuel lines. The bodys are made from tinplate wine cans bought for 99 cents each. They are interconnected by tinplate from a mineral spirits can that has been brazed in place and shaped. Three small screws hold the bodies together and another three hold the flame holder inside the aft-body. The flame holder has three tinplate alignment fins which also hold the inlet cone. The fins are brazed to the pilot can.
Here are the two fuel lines in place. While the picture is not clear they are both shower-head type fuel injectors. This means that they just have holes drilled in them. The fuel will dribble to squirt rather than spray.
Inlet. The inlet cone is a styrofoam egg from the craft shop.
The assembled engine has a total height of 28.5 inches and a diameter of just over 4 inches.
I'm looking at building a mount either on my car or on my truck to hold the engine into the wind far enough ahead of the front seat so I can see up the tail pipe. I will light the engine then drive into the wind. Since the winds have been running 40-60 mph lately I should have no trouble getting 120 mph airspeed. If all goes well I will add an airspeed indicator and thrust carriage to measure these.
Today I tested the engine. The results were less than hoped. I had too much swirl so the fuel went to the outside and the flame to the inside. When I overcame some of this I found that the fuel lines were too long and the fuel was boiling/pulsing. I also got into "buzz." Test report to be written up as TR-3.
Last week I had a chance to visit with the guy who designed and built the ramjet shown in the Windspire helicopter advertisement. That engine was quite heavy (about 5 lbm) and built in 1952 as I recall). He's about 75 and is now into U-shaped pulsejets. I gave him a paper copy of the ramjet portions of my ARLA work and he suggested that I write a book. Once I get my first engine flying I may stop testing for a while and write that book.
The following web site was brought to my attention, for which I am quite grateful. This set of sims is from Georgia Tech under the supervision of Professor John Olds, a very pleasant gentleman. I haven't tried this software so I can't describe it.
http://atlas.cad.gatech.edu/~jebradfo/index.html
After much thought and discussion I have decided to post William T. Decker's "Practical Ram Jet Design," 1954, as soon as I can scan and OCR it. This will probably take me about two weeks. A search for Mr Decker, Decker Engine Works, and/or any of his known relatives has turned up nothing. If anyone knows who his relatives are I would be more than happy to contact them.
I consider the posting of the paper a tribute to his pioneering work. His paper describes a much shorter design for a ramjet as well as some guidelines on the longer versions I have been working on.
This Page created May 11, 2000
Last Updated Sept 4, 2000