What is Digg?Sponsored by Travelzoo
Take Advantage of Ridiculously Low Holiday Airfares view!
travelzoo.com - Flights $52 and up for Thanksgiving, Christmas & New Year. But move on it now.
181 Comments
- tinkafoo, on 03/09/2009, -1/+78It's awesome listening to something extremely technical being spoken in a German accent.
- badqat, on 03/09/2009, -2/+76DARPA has paid for itself many times over. However, I suppose we do have them as the root cause of why we're on digg right now.
Granted, two-stroke isn't hip in terms of technology, but even if you're a snob you've still got to admit this is a pretty snazzy upgrade in the tech. - inactive, on 03/08/2009, -2/+71yah yah coooling! the accents made this even more interesting!!
- NSResponder, on 03/09/2009, -2/+54You didn't watch the video, did you? It's not just a horizontally opposed engine, it's a four-piston, two chamber engine.
-jcr - Walshboy, on 03/09/2009, -4/+52So this is what the DARPA initiative is up to. Then how did they end up on the island?
- aircool, on 03/09/2009, -0/+34I like this real world example:
http://pigeonsnest.co.uk/stuff/deltic/napier_delti ... - ryazwinski, on 03/09/2009, -1/+3440% efficiency compared to today's typical 20% - sounds good to me
- DPimp1262, on 03/09/2009, -0/+27That's a problem with translation. His english isn't flawless. What I think he was trying to say is that the design here is like a 2 stroke but with the ability for the exhaust to close before the intake. You can't do that in a conventional two stroke. That should vastly improve efficiency and make sure the engine is much more environmentally friendly. It sounds like quite the motor.
2 stroke engines are theoretically twice as powerful as their four stroke counterparts. The problem has always been efficiency and this seems to fix that. It would be very interesting to see if this motor makes it to production. - mastersmite, on 03/09/2009, -2/+29it isn't just a horizontally opposed engine. did you even watch the video? there are two pistons in each cylinder. i like the idea behind it, but some of it seems a bit off. i guess the guy was only talking about 2 stroke engines, but i know on most 4 stroke engines, the exhaust valves do close before the intake valves...
- portnoy, on 03/09/2009, -0/+26Two stroke engines have always been killer. Since they fire on every cycle instead of every other cycle they act as if they have twice the cylinders that a four stroke engine has. Add to that with this engine there are two pistons per cylinder and wow. Add to that the reduced weight because of the inherent balancing of forces and this thing looks really cool.
- inactive, on 03/09/2009, -1/+25Typically rejectionist comment fr/an apparently out-of-work `New York Times´ anti-Regnery book "critic." (You know, the ones who never read the book before critiquing!)
- inactive, on 03/09/2009, -2/+20Sweet. Eat that, Mr. Wankel!!
- GiJoeBob, on 03/09/2009, -0/+17You are referring to the Boxer engine I assume. Yes they have opposed pistons, this engine however has two more pistons on the outside of the typical Boxer setup, doubling the power in almost the same amount of space.
Did you even watch the video? - Neraph, on 03/09/2009, -4/+20First, the design at present only really works well as a diesel. With opposed cylinder engines, you have a very hard time finding an optimal spark plug placement to make this work well as a gasoline engine.
Second, with opposed piston designs like this, you're essentially relying upon fresh intake gas to push out exhaust gas, which isn't really the way fluid dynamics work. With a normal engine, the piston itself pushes exhaust gases out of the cylinder.
Third, modern gasoline engines use variable valve timing in one form or another precisely because there isn't an optimal opening/closing timing for the valves across the entire rev range. This design can't vary the timing at all because it relies on ports rather than valves, so it's going to have a relatively low redline. One of the advantages of this engine design would be that the pistons don't have to move as far as they would in a regular engine in order to extract power, which would allow you to raise the redline, but because the intake design is static, you can't really take advantage of this. - Samurai77, on 03/09/2009, -0/+14Watch the video.
- morphkons, on 03/09/2009, -0/+13Neraph
Welcome to Digg I see you joined today. Where did you learn so much about "fluid dynamics" in just 24 years on this planet?
Actually the fresh intake gas pushing the exhaust out is exactly how fluid dyanmics works in a two cycle engine. The opposed piston variant eliminates the need to loop scavenge and allows for the exhaust port to both open and close first: not possible in single piston (per cylinder) two cycles.
Four cycle engines need variable valve timing to overcome their inherent design weakness of flow restriction at the valves. (fluid dynamics) FTV - The opposed piston layout allows huge peripheral ports on both intake and exhaust. No restrictions.
If this design can pass the unburned hydrocarbon emissions tests, and produce 40% efficiency in a package light enough for aircraft applications it has a place and might well see production. - 1randomnumber, on 03/09/2009, -0/+13It can be done, but it's not feasible in passenger engines. They do harness the heat at stationary plants, and I suppose it's technically possible in VERY large mobile equipment. However, dealing with a steam/condensate system in a standard vehicle, as well as having somewhere to put said turbine, and dealing with the weight of it, creates more problems than it fixes. Also, I assume you want things like heat in your car when it's cold outside, etc. In that case, the steam turbine would be unused as long as you had the heat running.
Not saying the idea isn't used, for example, the refinery that I work at has a 30,000 horsepower Power Recovery Turbine that uses flue gas to send power back into the plant. But that turbine is the size of a bus, so it's a bit different.
Awesome idea, and on large things it's good, but on cars, the amount of heat generated, compared to the amount of heat harvestable, is kind of nil.
/is a mechanical engineer (with an electrical minor) - inactive, on 03/09/2009, -0/+13Not when it's YOUR physics professor speaking in a crazy German accent. I hope i pass that class... :(
- duewydo, on 03/09/2009, -0/+13"Granted, two-stroke isn't hip in terms of technology, but even if you're a snob you've still got to admit this is a pretty snazzy upgrade in the tech."
I disagree. Although for current generation RV equipment we are seeing a push for a cleaner 4 stroke. This is based of old designs and really we are all stuck in a paradigm. There is this concept that 2 stroke is dirty and for stroke is cleaner, but that is comparing a 2 stroke using technology originally developed in the early 1900’s. New 2 stroke can far outpace any 4 stroke, in power, longevity and clean operation. Don’t believe me? Take a look at modern train engines. These are diesel 2 stroke turbo fed direct injection technology. Although there is a lot more to it then just the engine to make this possible but I would argue that trains are some of the most efficient forms of transportation. This being weight and distance to fuel consumption.
The push for 4 stroke in RV is due to two factor. Longer life and operation, but mostly governmental mandate because of environmental issues. There is a push against moving to 4 stroke because it just cannot produce the same power to weight ratios as two stroke can. I love my 4 strokes but it is about time we move on from century old technologies.
As an example of stuck in the past. GM has finally moved away from the 350 v8 platform around 2000 for their LS platform. The 350 is a modified 235 v8 that was originally developed in 1954. So I own a 1998 chevy pickup with a 350 vortec. That engine is based off a modified, modified, modified 235 v8 from 1954. That is sad. Almost 50 year old technology. My 1988 chevy pickup motor blew. I got a 350 block that has a manufacture date from 68 and built a motor and stuck it in my 1988 EFI (TBI) pickup. That same motor would work in my 1998 pickup if I made a couple mods, (roller cam and swapped heads, or it would direct bolt in if I swapped EFI systems.) where is the innovation?
Long story short, There is a lot of potential to 2 stroke technologies through innovation. - FulcrumVitesse, on 03/09/2009, -1/+13I'm not a mechanic, but I can tell from the accent that this engine is pure genius. Now to make one that actually runs...
- alanhlake, on 03/09/2009, -2/+14Now, if all automotive engineering were done by a government bureaucracy, we would have...
- LiquidIse, on 03/09/2009, -1/+12I remember the days when the frontpage was full of these gems.
- joebaloney, on 03/09/2009, -4/+15"f/" vs "for " only save two spaces.
- stk198323, on 03/09/2009, -0/+9Everything to save money, get better efficiency and lower volume per horspower is welcome!
What do you propose, that we build military helicopter with untested hydrogen motor right away? - clinko, on 03/09/2009, -3/+122 Things he dances around that most people who know engines immediately thought:
1. What is the compression ratio (Paraphrased)?
If he doesn't have a "Head", then the other cylinder slightly moving or the piston rods slightly warping due to heat could be a real problem. Granted, this happens in normal engines, but here you have 2x the change on a hot vs. cold engine.
2. How is it cooled (paraphrased)?
A) He says it will be oil injected on the base of the cylinder? What? That's a revolution right there if he can pull that off. Forget the engine design. If it's 2 stroke, odds are that they'll just mix the oil with the fuel like all other 2 strokes. Not really eco-friendly.
B) He says there will be a smaller area to cool, so it will be easier... Ok... Sort of losing me. Think CPUs, a small area with a lot of heat needs a HUGE fan and cooling fins (relative to the area). Without running water around the cylinder, upping the weight, I seriously doubt that it could be air cooled. - duewydo, on 03/09/2009, -2/+11dead mule
- haentz, on 03/09/2009, -0/+9To be precise, it's an Austrian accent. Not that it matters...
- AlexanderBlue, on 03/09/2009, -0/+9sharks with lasers, funded by DARPA.
Silliness aside, DARPA competitions and projects result in some really great innovation. - jeffiek, on 03/09/2009, -1/+10invented the Model-T in 1989
- brstilson, on 03/09/2009, -1/+9Rotary engines are still more efficient.
- duewydo, on 03/09/2009, -0/+7“but i know on most 4 stroke engines, the exhaust valves do close before the intake valves...”
Actually. Not to be a smart ass but I think most modern 4 stroke employ a trick where the exhaust valve overlaps the intake valve or remains open for a moment while the intake is opening in an attempt to do a little exhaust scavenging. Most 4 strokes I work with the cam timing has some amount of overlap. The more overlap of the valve timing the more power potential. Production cars don’t utilize a lot of overlap as that causes a couple issues. Decreased fuel efficiency, emissions issues, and lastly poor idle. - S1ngular1ty1, on 03/10/2009, -0/+7Watch the video.
- TLNEditor, on 03/09/2009, -2/+9horse
- Ju1c3, on 03/09/2009, -1/+7in response to you number 2 answer part A. oil is already injected onto the base of the cylinders in our regular engines. honda has been doing it since at least 1989.
- JayTee44, on 03/09/2009, -0/+6I had the same idea too- only I thought of it just before you did.
- 4degrees, on 03/09/2009, -0/+6ja ja, naturlich!
- heiroglyph, on 03/09/2009, -2/+8So that was why Hugo had trouble getting the bus running...
- Nickolassc, on 03/10/2009, -0/+5I feel your pain man. What is it with crazy physics professors. Imagine Boomhower from king of the hill as your physics professor talking into the board, and only writing down equations while making inside jokes about quantum mechanics. He would always frown when we didn't laugh, so we started fake laughing to spare his feelings.
Ah, physics. Good times. - stegro, on 03/09/2009, -0/+5You know that DARPA is part of the government, right?
- Schmich, on 03/10/2009, -0/+5Djerman endjineering ja!
- portnoy, on 03/09/2009, -0/+4And why is that? Although the future will be electrics and fuel cells, internal combustion engines will also be around for some time. There is no reason for us to limit ourselves to just one powerplant technology.
- Otto, on 03/09/2009, -0/+4No, because both the pistons are then applied to the rotation. The inner one pushes, the outer one pulls.
- 80hd, on 03/09/2009, -0/+4Vwere still vworking on it :D
- nanixi, on 03/09/2009, -0/+4German engineering in da house!
http://www.youtube.com/watch?v=FB_PFMl0Azo - rotundo, on 03/09/2009, -1/+5I understand what you're getting at, but if you truly believe that then you also must disbelieve in the possibility of economic growth at all in a closed system, no? The idea is that they have developed tech that has grown the GDP more than the investment. There's nothing impossible about that, is there?
- heiroglyph, on 03/09/2009, -0/+4Wow, very cool find.
That one is from 1946, but according to the manual ( http://pigeonsnest.co.uk/stuff/deltic/delticintrod ... ), it was used in German boats before that.
So why didn't they become more popular (there must be a catch he's not talking about) and why does this guy have so little info?
The only thing he did was to cut it down from three cylinders, not a big leap. - rotundo, on 03/09/2009, -0/+4I believe that the rotary engine has better power-to-weight ratio and is more responsive, giving it an edge in sports-car applications, but that it tends to be less fuel efficient and have worse emissions, which is why it never really caught on. I always liked the idea of them, but in practice they just don't seem to be a great trade off:
http://en.wikipedia.org/wiki/Wankel_engine#Advanta ... - duewydo, on 03/09/2009, -0/+4You are using old 2 stroke design concepts. He mentioned direct injection; this means adding oil to fuel is not going to work.
In old 2 stroke design the mix is drawn into the crank before going into the combustion chamber. There oil and fuel mix works, here there is no fuel or mix in the crank. This means that a turbine must push the air into the combustion chamber and fuel is direct injected once the air is compressed. Direct injection is becoming very popular in diesel. The diesel 2 stroke direct injection is not as popular on smaller displacement engines because they are hard to start as you need a spinning turbine to force air in.(much the same problem you have on a jet turbine) but if you look at trains and boats you will see that it is a very successful and reliable platform. The exhaust turns a turbine or turbo and that pushes air directly into the chamber and then fuel is direct injected.
The crankcase has its own oil sump, like a normal 4 stroke car engine. I could see that design just having a dry sump on the outer pistons. A lot like what they do with high performance 4 stroke engines. My Suzuki ltz400 sport quad has two oil pumps and an oil reservoir. Pumps oil into the oil galleries and then pumps the oil back out of the sump and into the oil tank. So oiling isn’t an issue. “dry sump”
Now the heat problem you speak of, I see none. There won’t be 2x the heat. Even if there was more heat that just means that they would need a larger capacity on the cooling system side. That design could have a water jacket and have a water pump, much like what you would see on a 2stroke RV type motor. Example would be what you would see on a snowmobile engine where they have "jugs" for the cylinder. The jug includes the head, cylinder, and water jacket in one cast.
http://www.howstuffworks.com/diesel-two-stroke.htm
http://en.wikipedia.org/wiki/Dry_sump
http://www.grc.nasa.gov/WWW/K-12/airplane/cooling. ... - BrogMaN, on 03/10/2009, -0/+4I also had an incomprehensible physics teacher. Cheuk was his name, he's Chinese and teaches the class how I imagine a Samurai would. It's hard to explain, but the way he structures his sentences and the pauses and emphases he adds makes it sound as if we were physics soldiers, not students. It was equally hilarious and frustrating. It was difficult to hold in my laughter at times, but I could barely understand what he was saying so I ended up failing the class.
- tinkafoo, on 03/09/2009, -2/+5"Wankel" is funner to say.
-
Show 51 - 100 of 184 discussions
© Digg Inc. 2009
— Content created and posted by Digg users is 