I can't think of any way to justify the time and effort put into this engine, I'm kind of sad that I wasted the time reading this article, as are the people at the show that bothered to stop and look at it. Novelty at best. Complete waste of time at worst.
The purpose is for model vehicles. I have seen many scale model jets powered by real jets engines, scaled down. People who have the money to do this type of thing do it because they find it interesting and a challenge. I have watched these jets flown remotely at real speeds of 200MPH. Now that is a feat. Is it practical or important? Well, frankly no. Is it interesting and a challenge. Well, yes. Just discovering the issue with the oil is interesting. Who knows, there might even be a practical use for this knowledge in the future.
You are absolutely right, and the solution with cross-hatching of the walls of the chambers did not go unnoticed, and may serve some purpose in the future. My point was simply that the time and money could have been spent on something more productive and gained a better insight into something. This is old technology and certainly not something they were modeling to find a better way to do something. They were just having fun, and that's ok, because many advances in technology happen when trying to accomplish a different goal.
I would be curious to know if some kind of synthetic oil would have worked better in this situation, maybe we should get out of this, that oil may not be the best solution for lubricating, or that explosions and pistons are not the best way to propel things at this scale.
I totally agree, TJ, I was a little harsh in my first post, and I did admit subsequently that there is something interesting here, but I like to see new and exiting useful technological advances here. The problem they overcame with the cross-haching is, I suppose a Design News kind of item.
@akwaman: Cross-hatching is actually the typical surface texture for cylinder liners. The plateau-honing process described here is common. (Actually, it's more common to use a three-stage process rather than a two-stage process; the third stage cleans up the excess material left in the "valleys" after shaving off the "peaks"). You can find out way more than you ever wanted to know about cylinder liner surface texture here.
What's mainly interesting here is the small size of the engine. As a materials guy, I'd also be interested to know what the liner material is. I'm guessing it's probably gray iron, but not all iron is created equal. We've found that the cross-hatch pattern you achieve depends not only on the honing stone, but also on the microstructure of the iron.
As the document I have linked to shows, quantifying what a "good" hone pattern is is a very difficult task.
Yes, I too am astonished that the cross-hatching cylinders here is so celebrated. This was discovered and implemented by engine makers decades ago. That is the reason engine reboring and honing has pretty much disappeared. Now when they fix a car, they leave the basic block alone.
As for oil not scaling...seems an invented problem to me. They make lots of oils for very fine machinery. The cross-hatching was not necessary simply becasue they couldn't find oil for it, that's just the proper way to make an engine cylinder and bore.
Not to pick on the original "purpose" post [I most definitely am not]. I often think about those who are hypercritical of auto racing... "for what purpose?" they ask again and again... to get nowhere, round-n-round, in a big polluting hurry. Well I am one of a growing number of people that COMPLETELY understands why, what, and how this all has a purpose. I like the auto racing example because it exemplifies itself in some of our cars every day. When relatively strapped for cash I bought a 1996 Dodge Intrepid for my family hauler and grocery getter. It had 4-wheel independent suspension, loads of safety features, disc brakes on all four corners, a very low cg, Z-rated Low-Pro tires, cast aluminum wheels, short ratio steeting, the list goes on... NONE of those features came to the 4 door sedan without the tried and true venue of auto racing. Comparing that machine to the leaf spring carbeurated P.O.S. that was my dad's family hauler and grocery getter circa 1977.... YUP, there's a purpose. Oil chemistry and film retention technology are both HUGE factors in today's world as we up the power density on engines of any/all cylinder configs. While I agree that this project has limited applicaiton, the value of the lessons learned from it are yet to be calculated. Great posts, everyone!
George Leopold's talk at last week's Design & Manufacturing Minneapolis helped restore astronaut and engineer Gus Grissom's role in the beginnings of NASA, and outlined how Grissom played a pivotal role in winning the Space Race.
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