Bourke engine viability?

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stirlingk

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Cass256 The Bourke engine was way ahead of its time. It was designed from the principles of high pressure, high temp, fast complete lean combustion that does not produce CO2 and is very economical, and has a great power to weight ratio. Before you would even think about using this type of engine in an aircraft it would need a massive lot of operational reliability testing in varying environments etc, etc. I am hoping one day soon to build one specifically for a paramotoring application, but that may never happen.
FYI - the write up on the 'bourke engine' in Wikipedia is very biased and bags the engine without really understanding it. There is a lot of misinformation surrounding this engine, yet it is not an unproven theory, there are functioning bourke engines currently in existence, and they are amazing!
 

Aesquire

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For me, the Scotch Yoke is the deal breaker.

And I ran one of those shapers, too. RIT has a few in the classroom/shop and there were some scattered around Rochester, usually stuck in a corner with other obsolete tools.

The Scotch Yoke is a patent go around from the early Age of Steam. Those pesky proprietary cranks! ( sarcasm, it's a clever variety of motion changing tech from the days of manual looms and long before triple expansion steam engines )

Because the way the reversals of force increase in magnitude and severity as RPM increases, it's a slow speed, high maintenance solution to changing linear motion to rotary. Clever, yes. The precision needed no different than a traditional crank set, but unlike simple plain bearings, there's a serious problem with tolerance stacking.

Or in layman's terms, it's a sliding, banging, jerking mess of vibration and hammering. Could be a perfect solution for a mechanical arm needing sealing against vacuum or toxic gasses, but at, say, 10,000 RPM to get the power to weight ratio you need for flight, it tends to self disassemble.

If you can find a successful design using a Scotch Yoke for something other than a Steam Chest... ( the valves for a steam engine ) I'd be thrilled to see it. It was quite the new hotness in the 19th century.

Rather popular with Sterling engines, too.
 

Cass256

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Cass256 The Bourke engine was way ahead of its time. It was designed from the principles of high pressure, high temp, fast complete lean combustion that does not produce CO2 and is very economical, and has a great power to weight ratio. Before you would even think about using this type of engine in an aircraft it would need a massive lot of operational reliability testing in varying environments etc, etc. I am hoping one day soon to build one specifically for a paramotoring application, but that may never happen.
FYI - the write up on the 'bourke engine' in Wikipedia is very biased and bags the engine without really understanding it. There is a lot of misinformation surrounding this engine, yet it is not an unproven theory, there are functioning bourke engines currently in existence, and they are amazing!

I've found there's a lot of "bagging" on this engine without curiosity of the running principles.

As such, over the last few years I've been working on building a prototype research model to examine the thermal vs. kinetic output of specific fuel/air mixtures at specific compression ratios. Once I can prove detonation is more thermally efficient (+figure out the mixture where it occurs) I plan on building a rotary engine.

I've got the first prototype under construction, I'm just stuck needing 600$+ in raw materials right now... :/
 

Cass256

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For me, the Scotch Yoke is the deal breaker.
Agreed, it's a relic of an age past for sure. I believe it was used for ease of manufacturing, honestly. Pistons & jugs were much easier to make than rotary engines in the 40s.

The concept it provides of constant volume combustion is intriguing to me, though. LiquidPiston seems to claim something similar is giving them "more efficient combustion cycles".
 

PMD

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Yeah, another dreamer and schemer engine. You will note that SEVERAL proof-of-concept engines have been built and run and NONE of come anywhere near the fanciful claims of the original designer. In the world of 2 cycles, the efficiency of sucking into the crankcase (or under-piston space), reversing flow, transferring to the combustion chamber, turning it around and spewing it out are not very efficient - even though a regular piston-port 2 cycle SI engine can have phenomenally good power density. IMHO the first BIG red flag is the assertion that the piston stops at TDC. EVERY galldanged piston bloody well stops at TDC for rather obvious reasons. The difference in geometry between an articulated connecting rod vs. a scotch yoke makes such a claim ludicrous. Letting an aspirated charge compression ignite without any timing control is another that makes the claims quite questionable (as the pre-TDC cylinder pressures while facilitating detonation would not be controllable to manage BMEP curve to best take advantage of crank geometry vs. time (i.e. RPM). Believe it or not: there IS actually a solution to that particular problem that is well proven
( SmartPlugs - Daily Bea ).
I know the inventor and have driven his engines - a genuine genius and has done MUCH more that I can't discuss in public to revolutionize ICEs).

The idea that of running a scotch yoke at 15 or 20k is simply NOT what you will do without a tremendous amount of structure to contain the operating (or failure) loads. Another red flag for credibility.

Regarding the idea of making a smaller, newer Napier Deltic has been around for a while, but piston/combustion chamber vs. available injection components does not scale very well. The real answer is something like the stillborne Gemini or research 3 cylinder from Achates Power.

If you really want to think outside of the box, think barrel arrangement rather than Napier Deltic (or better yet Junkers 223) use the PROVEN tech that worked for Dynacam and put opposed pistons into a barrel configuration (actually has been done...see "Fair Diesel" if you can find any links/reference anywhere - IIRC Dr. Fair is a ME Prof so somewhat credible).

To the OP's idea of making his own engine: While it CAN be done by replicating proven designs by almost anyone with some good machining or subcontracting skills - to take a design from concept to workable has taken the OPOC examples I showed above from 1892 until now and STILL not a regular production item for cars, trucks and airplanes. If you have another century to go and many millions of bux - go for it. If not, go over to aeromomentum or somewhere similar and buy something more-or-less off the shelf that has PROVEN will do what you need.
 

Tiger Tim

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For me, the Scotch Yoke is the deal breaker.
Years ago I was trying to design the simplest possible expansion engine. The kind of thing I could slap together in my apartment with a hack saw, drill and a set of files. No illusions of changing the world, just something unique I could say I designed myself. Somehow I always ended up at a Scotch Yoke in it somewhere and would have to move on to the next idea.
 

Niels

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If you're not familiar with this type of engine, here's an article and here's everything else you could want to know.
What are your guys thoughts on this type of engine?

I think the idea of using detonation for power is genius, and if the claimed performance specs are anywhere near true (weighed 38lbs, 30cu in. making 76hp at 10k rpm, burns 1gal/hr at 6500rpm ) it could be revolutionary not only for aviation, but the motor industry as a whole.

Would it be worth it to pursue designing a one-off of this design? As far as I can tell, the problem everyone's run into with the engine is fuel delivery. A standard carb just doesn't work, and the original #001 engine ran with a constant velocity carb. I think this would be a great candidate for FADEC, though I'm not confident I could pull that off myself. It supposedly runs very lean, giving it great efficiency. Burning less gas would be a major benefit in my plane, since I can only hold 10 gal.

If I were to pursue making one for my plane, do you guys have any suggestions for parts manufacturers/mechanical engineers that could help?
It will be fun to scheme and the essential parts have run well but not in same engine.

Some clever ,well educated engineers from Esso lubrication laboratory near Southhampton UK was allowed
money ,time and workshop to make an X Parson Epicyclic fourcylinder fourstroke.

Time was around 1970-1975.
And desribed in technical magazines.


It was low mass but not easy to put in a car.
They went one bridge to far as they put a rotary Cross valves on top of each cylinder and never got lubrication OK.
The four cylinder X engine never ran smooth as is was fourstroke.As a two stroke crosshead with under piston scavenge pumping and a sidevalve on each cylinder it will run as an electric motor or a V8 FS.
To see if it is realistic let us agree on horsepower and rpm.May I suggest 80 horsepower and 40 rps?
The detonation engine is researched many places and is termed Homogenuos charge compression ignition.
Problem is that the motor can have faboulos efficiency at low load and extremely high maximum pressures when doing hard work.Do not combine novel ignition with relatively new mechanics and do not bet on making a living from it.
Good luck and I am starting sketching now.
 
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Aesquire

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The Atkinson Cycle engine in current Toyotas shows great efficiency, at the cost of power. Other versions with turbosupercharging may make for a better power to weight ratio.

Efficiency, pounds of fuel per horsepower, is the name of the game for car fuel economy performance, but runs heavier with a larger displacement. For aircraft, you also figure pounds of engine per horsepower, so without the complications of boost, may not be optimum.

( in my version of layman's terms, the Atkinson Cycle engine "wastes" some displacement to get more efficient combustion. Correct/enlighten me on that, please. )
 

aeromomentum

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The idea of the Atkinson cycle is to have a larger expansion stroke than compression stroke. We are limited on the compression ratio due to knock, octane and other things. But having a larger expansion ratio extracts more power for the given amount of fuel. Most modern car engines that use the Atkinson cycle do so by just holding open the valves during part of the compression stroke and this also increases pumping losses a little.

Another and maybe a better choice is an opposed piston engine with different phasing of the crank shafts. There is still a weight penalty since you are not "using" all of the possible cylinder volume but less pumping loss and no cylinder head weight. I think cheapracer was working on one of these in the past.

Then there are the turbo compound engines like the Wright R-3350 Turbo-Compound radial engine.
 

PMD

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The idea of the Atkinson cycle is to have a larger expansion stroke than compression stroke. We are limited on the compression ratio due to knock, octane and other things. But having a larger expansion ratio extracts more power for the given amount of fuel. Most modern car engines that use the Atkinson cycle do so by just holding open the valves during part of the compression stroke and this also increases pumping losses a little.

Another and maybe a better choice is an opposed piston engine with different phasing of the crank shafts. There is still a weight penalty since you are not "using" all of the possible cylinder volume but less pumping loss and no cylinder head weight. I think cheapracer was working on one of these in the past.
Since we are definitely on the "alternative engine" bandwagon, there is a really good writeup on Atkinson on Wiki: Atkinson cycle - Wikipedia

Opposed piston, opposed cranks all use different phasing of cranks to allow the exhaust to open first, dumping cylinder pressure before the inlet ports ( using forced air ) start filling from the other end. A quick search of Achates Power provides a lot of images and information.

Now we get to the REAL crux of the matter: spark ignition and aspirated charges have detonation limits. Compression ignition does not (thus how to solve the problem in a simple way....once again, see Achates).

It is all a matter of perception. The "wasted" intake cycle is more critical thermodynamically in a 4 stroke cycle. In 2 stroke cycle it is just not an issue. The ability to pack the cylinder to the pressure (mass, density) that you would like is far more flexible today using external pumping devices and controls. The resultant temperature can be either wasted in CAC or dropped by aqueous aspiration. As mentioned, with CI detonation simply not a concern. So, instead of trying to mimic the monkey motion conceived 140 years ago we can exploit the technology of the day to make the best compromise - and please keep in mind virtually ALL engineering and engines involve compromise.
 
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jedi

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I am interested in designing an engine from scratch, not necessarily using off the shelf parts, and I know this is no small task/journey. Do you have any advice where I could start with this? Should I go get a mechanical engineering degree? Should I try to find other people who might be interested in working for me designing this? I'd like to create an RC scale version for bench testing, using CNC milled parts or something similar.
Cass256 and any others interested in detail discussion please PM me for further voice discussion. Single channel simplex communication via keyboard does not facilitate efficient communication.

My subject of interest eliminates the Scotch Yoke and the rod and crank while allowing for variable compression, under piston oil cooling and no head cooling issues.

My resume includes Detroit Diesel, MSME from U of Mich. Williams research and General Motors turbine development and many years of general following of various engine projects. I am not by any means an expert on the subject but my 61 plus years of experience and impressions are yours for the asking.
 

Sockmonkey

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In my opine,

The Epicyclic Parson's would be a more viable project.

The video shows a single cylinder, which is easiest test
article, if you or a lurker is sufficiently interested.



Good luck chap.

The nice thing about that one is that you can have the under-piston scavenging chamber separate from the crank, and do a perfectly balanced boxer configuration two-stroke.

Now this fellow is an idea of my own.
oeuScRZ.gif

Reciprocating cylinder liners to balance the motion of the pistons and open and close the ports. Both using the epicycle crank motion. Moving them in opposition effectively doubles the stroke length without needing to enlarge the crank assembly.
 
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PMD

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Sockmonkey:

Interesting concept but would only run for a short period of time as the inner (moving) liner has no cooling path to outer (cooled) liner. Needs actual contact. Also no way to cool the piston unless there is a TON of oil flowing through the "crankcase" area.
 

Sockmonkey

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Sockmonkey:

Interesting concept but would only run for a short period of time as the inner (moving) liner has no cooling path to outer (cooled) liner. Needs actual contact. Also no way to cool the piston unless there is a TON of oil flowing through the "crankcase" area.
From what I've read, you can get sufficient heat transfer from a moving liner to the outer piston walls via the oil film if the tolerances are close enough.
 
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