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Bourke-Vaux's Engine.

NickD on Sat September 13, 2003 2:26 PM User is offline

Year: 20??
Make: Constant pressure
Model: XXXXX
Engine Size: 29 CID

From BigChris:

"It gets curiouser and curiouser! It appears the Bourke-engine.com site contains some obsolescent information but is primarily intended to sell you some ebooks and entice you into joining a spam mailing list. Don't be tempted, don't give them your email address! I made that mistake and within ten seconds got an ad for the Jackpot City Online Casino.

A little more digging turned up an outfit that has actually built and tested the Bourke engine and has now moved on to another design that they feel has more potential. The following url is a good starting place to begin reading and then use the buttons on the left side of the page to learn even more."


http://www.constant-pressure.com/News.htm

Moved it here Chris, unit of issue, "Big". interesting topic.

Sun'N'Fun is sponsored by the EAA, so must be a strong aircraft homebuilders item.

700*F EGT is quiet impressive, can run from 1,200-1800*F in a standard aircraft engine. But I see their engine is way over square, I am sure they had their reasons for that, probably the practical excursion of the yoke. Looks like they dumped the high CR deal and went to conventional ignition and they may benefit from OMC's loop charging design, that patent is long gone. See they want an air flow and an ignition design engineer to contribute time, ha, with a woman interest, may have to concentrate on making a couple of bucks.

Just wonder the the bigs guys aren't interested in something like this, they spent billions on the Wankel and that two cycle turbo charged engine from Australia. The former could never get the fuel economy, the later could never meet NOx requirements.

Different engine approaches are always of interest to me, but for some reason, we always go back to the 4 stroke piston-crankshaft, valved design. Still feel the turbine engine is the best and has a long history in the aviation field, the question is to make it cheap. Some thought on using ceramic rotors that can be molded by the millions.

Bigchris on Sat September 13, 2003 5:36 PM User is offline

Good "move" Nick! Bourke was obsessed with lean mixtures and ultra-high compression in the range of 24 to 1, but many fuels are too unstable to work at those pressures and diesel fuel couldn't be used unless it was atomized by fuel injectors. Bourke's successors found that the engine could be made much more stable and capable of using a wide range of fuels by using a more moderate CR and conventional ignition. No doubt the costs of development prototypes pushed them toward conventional carbs first with fuel injection to come later. The guys I pointed you to are looking for a magneto system for their engine so the ignition timing requirements are probably ultra-simple, because of the extended TDC available with the scotch yoke design.

Since they are pushing ahead with a flat four, I wonder if they ever considered mimicking the R4 configuration to give them a "pancake four"?
Seems like that would have it's place in aircraft applications...

NickD on Sat September 13, 2003 6:36 PM User is offline

So what you are essentially saying Chris, is that this engine is quickly reverting back to everything that was learned in the last hundred years or so about two and four stroke engines. The four stroke engine is still supreme over the two stroke, so maybe valves should be added and why not direct fuel injection?

So what this leaves than is just the Scottish yoke. I can see problems with that as well, as it is still a reciprocating engine, and that yoke appears to be a lot of mass swinging back and forth.

Somewhere in the back of my mine, I recall a similar fixed rod connected to a rotating member that converted rotating to linear motion, could have been in an old mechanical calculating machine, or in a tuning mechanism in an old military radio, or perhaps in a 40's mechanical analog computer. Ha, so much of that stuff back then, was intriguing just to watch it work. Have to give that some thought, but that would be simpler than the yoke with not nearly the mass. The fixed rod has to be maintained to maintain the TDC dead zone for complete combustion before the piston moves. With something like that, any 4, V-6, or a V-8 engine configuration could be used.

Food for thought.

Mitch on Sat September 13, 2003 6:45 PM User is offline

Maybe they don't want to make an R4 aircraft engine because of the association with the R4 compressor and its problems. Perception drives a lot of business decisions.

It seems to me that I remember the R4 being desribed as using a "modified" scotch yoke mechanism.
I can't find anything on that right now, but I kinda remember seeing an eccentric crank type thingy with forks on it that engaged the pistons.

NickD on Sat September 13, 2003 7:03 PM User is offline

This is all I have on it, not very clear, but shows the forks, bet Tim has one or two laying around that can be taken apart. Ha, let's put our heads together and develop a new engine.




The original post started off with the R-4, to the Bouke and back to the R-4 again. Something about design thoughts that leads you into a circle.

Edited: Sat September 13, 2003 at 7:05 PM by NickD

Bigchris on Sun September 14, 2003 12:15 PM User is offline

I used to attend design review meetings like that. I referred to them as "high-speed circle-jerks".

Thats a much better picture than anything I could find. On rethinking the pancake four as an engine I realized that that configuration would create balance problems unless you used two separate crank throws offset by 90 degress from each other. That might be doable but you'd lose the simplicity and cost effectiveness of driving both scotch yokes from a single pin. I can hear it now...pow pow chuf chuf pow pow...

NickD on Sun September 14, 2003 2:51 PM User is offline

There is a question as to if the pistons of the R-4 follow the same curve path as the Scottish yoke. If one does it, all four should, but I doubt if a radial design would be practical for an automotive application if even an aircraft application. Even with brand new radial engines the lower cylinders would load up with oil smoking up the airport when first started.

Just a concept thing to see if that large yoke could be eliminated and perhaps even come up with an in-line four. Balancing can always be done, somehow.

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