Thread: Ambitious newby

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  1. #81
    By firing on both sides at the same time i think you will be fighting the laws of physics. Equal Pressure on oposite sides at the same time will have double pressure in the middle?????? something will go bang as each side will be fighting greater residual pressure moving back out on climb surely?
    If the nagging gets really bad......Get a bigger shed:naughty:

  2. #82
    Who said anything about both sides at the same time?

  3. #83
    You do seem to have missed what I think is the most unique feature of my engine, the fact that it fires on both sides of the pistion essentially making it a one stroke cycle engine.
    Ah I read this as both at the same time??????????
    If the nagging gets really bad......Get a bigger shed:naughty:

  4. #84
    Nope, just one side at a time, but because each side has a 2 stroke cycle each piston fires on every stroke.

  5. #85
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Last Activity: 5 Hours Ago Has been a member for 9-10 years. Has a total post count of 2,149. Received thanks 237 times, giving thanks to others 5 times.
    It's still basically a two stroke, as each piston/cylinder takes two strokes to complete it's cycle. Just because you've stuck two opposite each other doesn't make it a one stroke!

    As for the original equipment question, a milling machine with a 4th axis will manage most of the bits, however you're also probably going to need a lathe for some bits.
    What you buy, will depend entirely on what size you want to build your prototypes.

  6. #86
    I said it's "effectively" a one stroke as each piston has power on each stroke. Obviously there are two strokes per cycle but each piston is doing both strokes at the same time(compression on one side, power on the other). I'm not talking about opposing cylinders/pistons, I'm talking about two combustion chambers per cylinder for a total of 8 combustion chambers, just so we're clear.

    Eventually I want to build a full size model and I don't know if I'll have the money again so I want to buy the best I can right away.

  7. Hi Brett, I'm a Newbie here to, so a hello to you.

    Your post really grabbed my attention as I am an Automotive Engineer who has spent the last 20-odd years in and around engine development (10 at Lotus Engineering, the rest spread fairly evenly amongst Jaguar, Land Rover and Perkins Diesels). I have worked on both the theoretical side - carrying out engine and vehicle simulation, as well as the practical side of performance and emissions testing. I have a love for weird and wonderful engines of all kinds and despite all the evidence I have seen to the contrary in the last 20 years, I still retain a small hope that we will someday find a better solution to internal combustion than the Otto-cycle.

    I have been really reluctant to inject some more reality to this post, especially in the light of the way it has been delivered to you and I'm afraid, received in previous posts, but my advice to you is please, please only look at the building of this engine as an interesting and diverting hobby and please do not even remotely consider any commercial applications for this engine, it has far too many flaws (even with computer controlled injectors) to get close to the performance of a conventional design mechanical injected design, let alone the state of the art computer controlled engines now being built.

    The forces of Diesel combustion are quite frankly beyond a yoke of ANY design, the crankshaft was chosen many, many years ago as the best solution to convert linear to rotary motion, even before the internal combustion engine came about and for good engineering reasons. These were learned the hard way, by experimentation, breakage, the odd fatal injury and constant redesign. Take a look at early steam engine development, you'll find it nearly, if not totally, impossible to find a new way to convert linear to rotary motion.

    I could go on with reasons for this designs impraticality, but I think enough has been said already and I think you would find the following much more useful than what could be construed as continued "nay-saying". If you do want to look at practical realities and ideas regarding the Infernal Confusion Engine, I can strongly recommend getting yourself a Bosch Automotive Handbook if they still do it new. Used copies are going from 17 to 199!!!! mine cost me 16 20 odd years ago! This explains(explained?) a lot of the (then current) technologies concisely. Also treat yourself to a copy of the "Heywood" Internal Combustion Engine Fundamentals book (17-160 from Amazon) and read through that to get an idea of what you are up against when dealing with internal combustion. These were and probably still are, very much referred to in the industry. I've been very ill and out of the industry for the last 6 years, so things may have moved on book wise, but the chemistry and physics will still be the same!

    I would also once have recommended you contact the R&D department at Lotus for their ideas on it, When I was there 1990 to 2000, it was not uncommon to receive such requests for help and we would reply in a polite and professional manner even if the ideas were totaly crack pot and I have to say we really did get some weird stuff! If you are lucky and some of the "old boys" are still there, you might get some plain and simple advice for free! On the other hand things have changed there so much since I left, I'm not sure what response, if any, you would get now.

    I would seriously start with small do-able jobs such as conventional 2 and 4 stroke models and see what issues there are in making those work properly before you embark on the task of an unproven design. You are on a massively steep learning curve, take it steady and keep it real!


  8. #88
    Quote Originally Posted by BikerAfloat View Post
    you'll find it nearly, if not totally, impossible to find a new way to convert linear to rotary motion.
    There is one the steam engine fanatics are playing with

    Mount your drive shaft on a couple of bearings.

    Extend it forwards and mount a plate with more bearings so it is free to spin on the same axis.

    Bend the shaft behind the plate. Tie the plate so it can wobble but not turn.

    When the shaft turns the edges of the plate reciprocate so you can make an engine.

    The transmission forces are horrendous but you can use monster bearings to compensate.

    There are lots of movies on the web and they are quite fascinating to watch because you can go on adding cylinders 'til the cows come home.

  9. #89
    Thanks for the advice Geoff. I didn't consider your post naysaying because you backed it up with facts and real experience. I looked but could not find any information on the limitations of the scotch yoke. The books you recomended sound like exactly the kind of thing I would be interested in. I don't mind a steep learning curve as long as the information is available. It seems like all the books or websites I have found are either ridiculously simplistic or very specialized. I don't have my heart set on this design I just think that simplifying is the answer to many complex problems, a philosophy I believe Lotus has always embraced as well. Thank you very much for your insights and I hope to chat with you more. This engine is not my main motivator for getting into machine work it is just something to discuss while I wait for the funds. I also plan to purchase a 1970s Datsun Z(I'm afraid Lotuses are a bit cost prohibitive here in the US) and rebuild an engine from a 1980s 280ZX turbo to swap into it. I don't know if head shaving is a bit advanced for a newby like myself but I may try it. I am just the type of person who likes to create things and metal seems like a wonderful thing to create with.

  10. #90
    Click image for larger version. 

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    I came up with a variation on the yoke that I think could solve some of the issues with not being able to deal with the stresses of a diesel motor. Instead of an open yoke that the crank slides in it has a round insert that spins inside the rod and off center on the crank. The diameter of the crank is half the stroke of the engine. I'm not sure if this increases or decreces the stress on the crank but the sliding and hitting of the yoke is gone.
    Last edited by brsanko; 01-09-2012 at 02:50 AM. Reason: Trying to add picture

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