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jlcortes! I remember You saying something about gp7 desmosedici. Did you mean the desmodromic valve system or something else? Well it would cure the problems that NC Cams is talking about, i think...
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I have absolutelly no doubt that NC Cams' posts are not meant to deter people, and that they are genuinely intended to be a 'realistic' point of view.
When I read them however, I also get a slight feeling of pessimism.
The problem with text-only conversation is the lack of tone in the writers voice which would, in spoken conversation, convey a lot of information to the listener.
We've all seen discussions that get seriously out of control on the many forums on the net, simply due to missunderstandings.
On the subject of Jlcortex's project, well, many people speak of 'Dreamers' and 'Doers'.
The idea being that Dreamers are bums, they get nothing done, wasting their lives and Doers lead busy and productive lives, an unfortunate point-of-view that is prevalent in our society.
I have my own twisted version of this.
I believe in Dreamers, Doers and Dreamer-Doers.
The Dreamer is an idea's man(or woman) who uses his brain to invent and theorise, while never actually making anything(or only a little). Examples would be Leonardo Da Vinci, Einstein etc.
Most dreamers struggle in life unless recognised for their brains or lucky enough to be in a job they really enjoy, or as lecturers at colleges/universities etc.
Doer's are the people that appear to have tons of energy, most are skilled craftsmen and produce beautifull work, these people are usually employed to do the manual work for the Dreamers. I can't right now think of any famous Doers, though I am sure the list would be expansive with a little research.
The Dreamer-Doers are the people that combine the above qualities, they are blessed with both bright idea's and manual skills. Examples would include the Wright Brothers, Isaac Newton, Michael Faraday, Nikola Tesla etc etc.
These people are usually very successfull in life.
The famous people used as examples above are only indicative, the businesses and companies all over the world are filled with them, from the corner locksmith or engineering firm, even the local bakery or the girl in the office, right up to NASA or Bell Labs etc. Most have a mixture of all three types.
Note that not one of the above groups is better than the other, many things we take for granted every day simply would not exist if just one of the three groups above also didn't exist.
I see Jlcortex fitting nicelly into the third group, the Dreamer-Doers. He has a dream and he's doing something about it, himself. I have no doubt that he will have a finished engine as it is apparent he has the skills. Whether the engine lives up to his dream is only limited mostly by his drive, less so by money.
I, unfortunatelly, fit mostly into the first group. I'm always coming up with idea's. I have piles of scrapbooks filled with scribbles and sketches.
I do have a little bit of doer in me, but most of the time the doing bit never seems to get done because I've moved onto dreaming about something else!
It is frustrating at times.
I'm sure all the famous people mentioned above were told they were wasting their time, that the things they are now famous for couldn't be done.
If everyone in the history of human kind believed the problems they were told lay ahead of them, we would still be living in caves!
Or would we? Someone probably told the first caveman it couldn't be done!,
that fire only came from lightning strikes, that a rock would never crack grain or open a nut.
Imagine going back in time and telling an 18th century sailor that humans will travel the sea's in days instead of months, he'd tell you it couldn't be done.
"Ofcourse it can! It just hasn't been done YET"
Edit: EEP! I had Michelangelo as a dreamer, ofcourse I meant Leonardo.
Last edited by RotaryNut; 06-13-2007 at 12:01 AM.
jlcortes! I remember You saying something about gp7 desmosedici. Did you mean the desmodromic valve system or something else? Well it would cure the problems that NC Cams is talking about, i think...
Some historical perspective into my "reality based" replies:
I spent nearly 7 of the first 10 years of my engineering career answering tech inquiries - mostly by phone - of guys whe called a major race engine parts supplier. After 5 years of anwering essentialy the same questions, I got the urge to catalog the info so I wouldn't have to answer these "basic" questions. Even then, guys would call and ask the same questions, over and over - even though most if not all the queistions were already answered in the catalog. At what point does ANYONE get tired of answering the same questions the same way????
Eventually I moved on and gravitated toward more technical aspects of engine parts engineering. This eventually included learning how to design cams. That progressed into a need to have to gind them. Why? Because you couldn't GIVE away the engineering unless you could make them. Since there are no schools out there to teach either, dreaming necesssited studying which evolved into doing.
The realities of business set in BIG TIME, when you have to spend in the vicinity of $100K or more to take a dream into a reality. Dreaming turns into pessimism when business is slow and you get the inevitable "all you have to do is's" thrown at you by someone who's never done it before. It gets even more challeging when payrolls and/or tax payments are due.
We've gotten the "all you gotta do's" over and over over the years and more often than not by guys trying to go from hot rodding something to race to that of truly designing and building something to race professionally. There are lots of guys who talk a good story. Making valvetrains live at 5 figure RPM levels is not easily achieved by ANYBODY.
Yes, verbal inflections are lost in message boards. None the less, valvetrain engineering is a tough task, even if/when you KNOW what to do and how to do it. The prior post says volumes - believe it. To those who don't like what I say or how I say it, the information presented can be readily ignored as the reader see's fit. However, if the info helps someone NOT to do something dumb or irresponsible, I've achieved my goal(s).
Desmodromic valvetrains are NOT readily made or designed. Why? Because you not only need a cam to generate an OPENING motion but you also need a "mirrored" cam to provide resisitive force to provide the opposite and reactive CLOSING motion/control.
Since you still need to control the valve on the seat and keep it closed when motion is not occuring, something is needed to keep the valve closed. The cams could be used but, even so, a spring (torsion or compression) still provides the most effective, simple closing/seating device. Making cams do the work over the wide temp ranges of growth is asking a bit much.
Desmo's will RPM quite well when you get it all figured out. Production tolerances is/are a nightmare not the least of which is due to the duplicity of complication involved to grind the cams.
It should be noted however that a new technique called "valve lofting" has been gaining favor in a number of racing applicaitons. This is a situation whare you INTENTIONALLY toss/float the valve over the nose of the cam at the peak RPM ranges. It is NOT easily done and requires a lot of testing and development but it can and is being done. The NASCAR Nextel Cup teams regularly use the technique. THis neat trick violates any and every reason why you'd use a desmodromic valvetrain.
To those who doubt the validity of the lofting concept, tHere have been articles written about it in "Circle Track", "Stock Car Racing" and even "Racer" magazines.
Well i've never said that desmodromic system is easy nor is it simple but it cures the problem of "floating" (I'm sory if i'm wrong, english is not my native language. As "floating" i understand the situation when RPM is so high that normal coil spring is not fast enough to close the valve on time) This is an f1 engine project its basic ideas make it very complicated....
Hi NC cam
I'm taking a stab in the dark here now , NC Cam i would have to say is a senior member of this forum group , age mmmmmm about 55 to 60 years of age. Correct me if i'm wrong NC cams' please.I do not intend for my posts to be optimistic or pessimistic - just realistic.
NC cams , in your wildest dreams as a teenager in your 15 years of age , would of you ever thought you would follower the path your career has taken you ? and do you think with all this R & D research you would of acquired all this knowledge ?
I'm not having a go at NC cams' , guys i'm merely observing his remarks and advise NC cams' gives out to people.
It is great that he is a very active member on this forum and i imagine other forums as well.
Many people in the human history have been labeled crazy in centric people , and many great inventions have been invented through out history.
There have been many people come up with ideas and not complete them , and others pickup where they have left off and complete the works. Does this make them a dreamer or a time waster.
No doubt knowledge is a power tool and may aid someone in solving problems quicker than another person who has to iinduor the hardship of experimentation and find out what makes thing tick.
Guys it is great to see all this input , but remember many different spring control ideas have been exposured out in the race world. Some succeed and some fail.
But the guys that fail i wouldn't be placing them in the dreamer basket.
cheers Guys
ps : Just because something doesn't do what you planned it to do in the first place doesn't mean it's useless. - Thomas Alva Edison
Reply to Igor: Valve "floating" is NOT necessarily detrimental to engine performance IF and ONLY IF you know how to manage and control it. This is where "lofting" has come into play.
Lofting is the intentional "floating" of the valves to gain area under the lift curve. It is done to help maintain low RPM torque via the use of smaller then normal cams. The "lofting" comes into play at high RPM where the small cam starts to lose the ability to feed the engine enough air. By lofting, you gain the area that a larger cam would supply albeit with the use of a smaller, torquire cam. Lofting also reduces fiction at that point when separation actually occures between the follower and the cam.
Reply to FPV: I am in my late 50's. As far as my "dreams" were concerned, I wanted to be involve with automobiles in an engineering capacity almost as soon as I discovered them. I tinkered with cars, models and such throughout my childhood and that got into car tinkering in my teen's. The whole time I was in school, engineering school was the objective/dream. Why? Because learning engineering whould/should enable me to make/build/design faster personal cars.
After I attended my first car race, THAT became the focus. The quest for engineering knowledge was a means to the end - the end being building faster cars. Even when i became an engineer, i got involved with RC race cars. Even never having owned them, my prior chassis knowledge of 'real' cars enabled me to be devestatingly fast with relatively mundane equipment. I both outspent and out tech'd the competition - as an "old mam", I didn't have the reflexes of the kids but I sure had the power, funds and the technology.
Did I realize that I'd be where I would end up? Essentially, that was my plan from the get go. Become invovled, become good and then (hopefully) win. In spite of NUMEROUS business obstacles in a politically riddle industry, we were able to carve out our niche. Thankfully, people I met along the way gave me opportunities to apply my skills/trade. The "expertise" had to be proven and the respect earned but the knowledge, well, i got that the old fashioned way - I bought, piaid for and learned whatever I coud, when I could.
Success is a product of inspiration and perspiration. The inspiration part is easy to get. The work part depends on how badly you REALLY want it. The SUCCESS part comes ONLY when you work for and truly deserve it.
to NC Cams: Thank You, i get it now.
I've been thinking about these rotary valves sealing problem and i've came up with this. I don't know if the idea is already old but thats something like this:
http://img238.imageshack.us/img238/596/rotaryyy7.jpg
The rotor has a "cone like" shaped center part, which fits the head. there's a weak coil spring on the one end of the rotor, which pushes the rotor against the walls of the head thus creating impassable wall. I have to think about the heat generated by the friction and lubrication of course, but thats the general idea. What do you think?
P.S Sorry for those poor drawings made in Paint, but i don't have any drawing program like CAD or else, and even if i had, i wouldn't know how to use it :P
Igor: your "idea" has merit until/unless you look futher into the realities of first MAKING the part and then having it FUNCTION and then LIVE.
Re making it: the challenge would be to make the female sealing member that the conical member rides in. How to make it is an issue as grinding would surely be mandatory. How to grind a tight, ID and a conical one that MUST closely and TIGHTLY seal against the cone will be the challenge.
When/if you make it, then how do you make it live? To seal, you want FULL circumferential sealing. Yet, that sort of fit is perhaps the worst thing to first achieve and then to lubricate, ESPECIALLY since you're now asking SLIDING friction to be resisted. Sliding rubbing seal durability has been a challenge in the wankel as long as it has been made.
This is also why poppet vavles remain SO popular - they are simple/easy to make and they live/work for long periods because they do NOTh have high force relative sliding motion occurring between the valve face and seat.
IF you can get past the siezing potential of a conically shaped part you propose (which will try to self lock in the female recieving member, by the way - after all, it is not unlike a locking taper in a machine tool spindle), you then have to lubricate the sliding elements (male and female).
Moreover, you also have to generate precisely finished sealing and wearing/rubbing surfaces out of materials that will NOT deteriorate, wear or sieze when hot, corrosive 1400+ Deg F or higher combustion gasses impinge upon the surface that faces the combustion process. Figure that out and you'll have something.
Perhaps I'm sounding "pessimistic" - but sadly, SOMEONE has to bring up these nagging issues of reality that are easily overlooked when folks do daydream sketching/concepting.
I, too, have had some (no many) napkin sketch ideas over the years. However, when you are forced to do a production or operational assessment of the concept prior to making it, or having it design reviewed by peers, i've learned that some "great ideas" are often relegated to the "nice try" heap of life.
Well, with all the facts You just got me familiar with its rather realistic then pesimistic... I'll try to think of something else. Maybe you have an idea how did coates cure the problem? It would be really helpful. And i found a vertical
version of my idea... Here it is. Its the first one i believe... http://www.dself.dsl.pipex.com/MUSEU...aryValveIC.htm
The rest of those are interesting but all, as written here, unsuccesfull
EDIT: Their site says they use "floating seals" What are those? How do they work? I cant find any info on google...
Last edited by IgorWojas; 06-13-2007 at 05:20 PM.
Ok, I found another interesting thing but this time on my PC. This engine actually runs, "lives" as you call it. As i remember the constructor ran it on RC plane and as he said it was a very succesfull project. It doesn't seem like complicated, especially he made it on his own. http://img404.imageshack.us/img404/5160/4stscrvbwx3.jpg
EDIT: Another one, also on my PC (im really delighted by what can i find on my hard drive!!) This was i think a 125 dirtbike mod, i don't know if it ran because the site was in spanish... But it is also a good approach, unluckily very poor quality of the pics. http://img253.imageshack.us/img253/981/hoytrotvqj8.jpg
my electronic fuel injection are ready to be tested. it is originaly designed for dirtbikes and ATVs but it could works in any 4 stroke engine.
it will be ideal for my prototype engine.
i have order some custom enclosures from a rapid prototyping supplier, it is really fun, it is easy to build very complex parts in some days!
Jlcortex
http://www.sportdevices.com/jlcortex/
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