@@stianmathisen4284 most of the surfaces in an engine never contact one another, they ride on a thin film of oil and any amount of metal-to-metal contact should be considered a mechanical failure. larger contact surfaces = way more oil shear forces = more losses. the main reason modern car engines are moving to thinner and thinner oils is because the engine oil viscosity contributes a huge portion of the total frictional losses
The sliding box section of the yoke design would make lubrication a lot more difficult to achieve effectively than with standard plain bearings on a normal crank pin.
as a new comer marine engineer cadet, i have to say that the sliders that are being used on the 2 stroke low rpm diesel engines, are made of white metals, that are cheap and are the first to wear out, so damaging of the engine can be avoided. In those engines are vertical, but yoke sliders are on the side, something that will incise friction and wearing out. Because of that i am very interested to see with what they came out to stope that problem.
Not really, it would be feeding oil to the crank and thus the square itself through feed holes, exactly like normal cranks. And voila. Have it squirt oil just before and after the lead and end corners of each slide surface of the square, the same way we use piston skirt squirters. Just have it squirt the slides instead. Bam done. The early Scot design probably only relied on paddle oiling like push mowers so it's no wonder it failed.
@@ShogunAutoworks it slows the wear out, but yes, if it is lubricated properly, then the life spend will be increased to that of a piston' s spring, or even more then that.
There could be needle bearings the same that are used in some high horsepower cam applications. However, there could be a round design instead of a square crank design.
There is still significant friction against the cylinder of the scotch yoke design: the off-centre force from the crank pin on the yoke causes a torque, just like in the connecting rod, which in turn torques the piston inside the cylinder. The force on the cylinder wall can be reduced by increasing the piston length, similar to how the lateral forces are reduced by lengthening the connecting rod.
No , the short edges of the scotch yoke's "square" run up and down linear bearings ( 9:40 648 & 650 in the diagram are bearings) in the crankcase walls. This eliminates side loads on the piston. i.e. The square also acts as a crosshead , as used in steam engines and large (ship size) diesels For some reason most commenters fail to understand this
I think you are missing the fact that the off-axis force still exists. So you will need restraint against rotating of the yoke due to the moment (torque).
@@paulgee-i7j Got it, so you have more reciprocating sliding surfaces and more reciprocating mass. You also have much more difficulty in maintaining tolerances which is why such designs have only been used commercially in low speed applications such as diesel ship engines. You just moved the problem (which has long ago been solved) to a more problematic location. YAY! I love designs that rattle themselves apart due to problematic tolerancing requirements!
I am a pilot. Although I spent most of my career flying jets, perhaps my favorite piston aircraft engine is the Lycoming IO-360. It is a 6 liter, 4 cylinder engine. How do they manage to make a smooth 4 cylinder engine that big? It's an air cooled boxer. The secondary balance problem was solved a long time ago, 23 million Volkswagen Beetles can't be wrong.
boxers are very suitable for larger displacement due to their inherent good balance. vw beetles were built to spec so are not the pinnacle of engineering, just good enough. a boxer 6 is even better than a boxer 4, ie porsche.
lol i was thinking the same thing, this design but in boxer engine would get rid of many problems he talks about, and if you make lets say, a 8 cyl boxer, with two pistons per rod assembly, you get rid of the weakness in the bottom rod cap
You not only have sliding friction but also every moment of movement places a different direction of sheering force on that slot as you convert circular motion into lateral motion.
We had a horizontally-opposed Scotch-yoke engine designed three decades ago. Each piston was double-ended (you still need to keep that yoke from moving, there _are_ side forces!) with the yoke in the middle. We never got around to building it, but in my retirement I may do so. Gotta make it a four to keep the balance even close enough to live with!
@@klausbrinck2137 And it's added friction... That whole thing about no sideloading on the piston is unfortunately not true in the configuration that was shown in all the animations. Adding linear bearings to keep the yoke from moving sideways would take out a lot of that, but it would add friction at yet another point. It's a case of saving friction in one place and loosing it in three others. So sorry, but I can't see how this would be able to revolutionize engine design. People have tried it before, and will try again as everyone is certain that no one else understands just how great their particular idea is. And there's nothing wrong with people trying to refine ideas, but it become stupid when you have to ignore science for your idea to make sense.
Thanks! As always you manage to explain things in a manner that it makes them look simple even if I know they are not. The best automotive channel from my point of view.
Scotch yoke engines make more sense as a boxer engine I remember reading a article on how it would change engines forever and that was 20years ago still waiting.
As mentioned in the video, there are still inherit issues with the Scotch/Yoke engine that is still keeping it in engineering development. Until then, a conventional piston mechanism is still the preferred choice for mass production and applications.
The Scotch crank has been arround for ages . It's ONLY advantage is that the piston moves sinusoidaly . Greater reciprocating mas more sliding friction , a total non starter that should remain a historic curiosity .
The yoke needs a tail guiding section below the connection to the crank to overcome piston ossilations within the bore from the forces of power stroke and compression strokes. The line of force moves from one side of the yoke/crank connection on every cycle.
Came here to write a similar thought. The forces on that large "see saw" will cause huge friction on the piston to bore area. Adding more stabilisation to counter that just makes the friction elsewhere increase .
do you have any concrete evidence that their claims of the superiority of their engine is not baseless, and they aren't just sitting around twiddling their thumbs saying "working on it" while drawing a wage until the invested money runs out?
I don't and neither does anyone but society is built on the concept of innocent until proven guilty. No one has said proof for thousands of different companies but we can't go arresting based on assumptions without proof. Ps it goes the other way too. Do you have concrete evidence they're doing what you claim? Or any other company. You also don't have concrete evidence that I'm not a thief but you can't barge into my house because you can't get a search warrant based on a hunch that I'm a thief.
That's the way most startups work. They have an idea and maybe a few patents, and they burn through capital until they have something worth selling. It's a speculative investment; most of them fail but some make it big or at least get bought out profitably. If you don't like the idea, don't invest in them.
The most important part is getting rid of the far more severe sliding-friction in the cylinder/piston -interface... High combustion temperatures let metals get soft, and ease the destructive effects of sliding friction. Friction doesn´t come from nowhere, it simply leaves the cylinder, and goes somewhere, where the situation is far more under control, cause it´s cooler.
You get the benefit of longer dwell at tdc and a few other things on top of that. Scotch yoke engines aren't exactly a new thought, the first ones built were the Bourke engines iirc. They're quite interesting, and it's without doubt a feasible concept. Iirc some larger companies experimented with some such rather recently because the longer dwell time/slower movement around TDC was supposed to have advantages for HCCI engines or something like that.
The slider bracket would have to have a guiding groove andthe guide square have guide nub. Starting this would require a starter on the crank and timed firing. It seems rather extensive withmore draw backs for mass production. The lower crank case would need testing as well
Funny in 1976 my father and I built a 2 cylinder apposed Brouke scotch yoke engine. We used a roller bearing on the crankshaft, but on our first crankshaft the rod journal was to small and it sheared off. Second try we used a Kawasaki 100cc crankshaft. I believe that an apposed 4 cylinder may solve some of the balance issues. We were able to get 10,000 rpm underload but were unable to spin it faster due to it having a carborator and a distributer out of a 1960's VW. Using modern direct injection and ignition this may actually work.
if you like new engine ideas, you may like the liquid piston engine. It seems to have a lot of potential, by being able to run in a variety of fuels, with high efficiency, and being simple and light weight. There is not much videos about it, so if you find it interesting, you could make a video about this engine, and at the same time help the engineers by making their job known.
It does sound interesting, but at the same time the company and people there have too many... "questionable" stuff behind them. I'd love to be proven wrong, but there're too many signs that it's an intentional scam, just to grab investors' money.
@@dirtyclanner2250 they are developing the engine from 2004, with the final design been made in 2016. From then, they are involving it, trying to make it more efficient and more powerful. They have a small museum with their previous designs and fully workable prototypes, and in their website, their looking for new engineers, so calling it a scam is a huge claim for which there are no evidences.
@@reedhanson5945 they have relish. It is all in their website. Also don't say that something is a crap before it get tested. The LP engine doesn't need more lubrication oil then a usual engine, because the friction that is experiencing is mostly rolling friction.
The LP engine would be great for small aircraft but I am skeptical if they will ever make an engine that does not need overhauled frequently. The Achilles heel of the design is the seals, not at the tip like on a normal rotary but on the sides of the rotor.
I think the Scotch yoke rod should slide between rails, to keep it straight and in linear motion. Now the force of combustion will try to tilt it and the piston, which is much worse than pushing into the cilinder wall. Great idea though!
Yes, real Scotch yoke engines do have rails to constrain the "big end" of the yoke, which are omitted in this video. They are visible in the small model engines shown in this video, and in the Alfadan patent drawings also shown in this video.
I see a torque at the piston in that configuration. Much more than in the traditional design. I would guess that this would greatly increase wear an the potential of engine failure. In the traditional design, the piston is pushed against one side. But in the here presented design, the piston will get tilted. Seems like a bigger problem to me.
Yup, not only that but you might need a longer piston head to reduce the moment-induced forces at the corners, increasing the contact area of the piston walls and increasing friction. Then there's the arm which would probably need to be much wider to survive the bending moment without fatiguing. Then he also says there are fewer parts because there's no hinge between the head and the arm, conveniently forgetting that those extra parts have just been shifted down to the sliding block connection. In general mechanical engineers like to say that they prefer rotation over sliding wherever possible for reliability. There's so many practical reasons why this theoretically better engine just isn't better. Engine builders haven't just been ignorant this whole time, they've converged on the conventional design for good reasons.
@@excrubulent In addition to that, bearings, or anything round, is easier and cheaper to manufacture. Sorry for spelling errors, i usually speak german ^^'
@@darysparta9676 first of all "piston axial torque" isn't a thing. Not sure what you are referring to. Regardless he said the secondary forces are "much less pronounced". He did not say anything was eliminated.
It seems one would want roller bearings inside the slot. Is there a hidden problem with that? And maybe a hydraulic mechanism to keep contact with both sides of the slot (kind of like hydraulic lifters) as it wears?
This does nothing to reduce piston side forces, they're still there just the same as the geometry is still the same. It does dramatically increase reciprocating mass though, so I guess that a plus? Quite literally the only 'benefit' I can see here is better balance, but there's much better ways to resolve that problem.
Just looking at the scotch yoke design, I would expect it to be a better proposition in horizontally opposed engines, simply becaues each cylinder will support the straight movement of the yoke assembly, also able to optimise the strength of the yoke on both thrust surfaces without adding extra material. I would also expect this layout to reduce any balance issues. Surprised the likes of Porsche and BMW (Motorcycles) havent tried this in their boxer engines.
Boxer engines are a subset of horizontally opposed engines that don't use the same crankshaft pin so wouldn't work like you say. If I'm understanding what you're saying correctly. This would work on some flat engines, but not on boxer flat engines which are what Porsche and Subaru use.
Very interesting. So Alfadan didn't actually "reinvent the connecting rod" (their words not the video presenter's), they refined an existing design. I hope they succeed in bringing their technology to market.
@@nenume00 Alfadan is a scum 100%. They just want investors to give them money. The owner will take all those money and deliver nothing. The money will go to his own pocket to finance his car, his boat, his mistress etc. Thus the mentioned in marketing material engine will never happen. Never.
Scotch yoke.... I'm in Perth Western Australia and two different local companies made versions of an engine known as the Bourke Engine (USA 1960's). Bottom line frictional losses were too high, as was wear. LOL. I typed this as your video started... You covered most of it in your video. However.... One was Sarich Technologies...Circa 1987. I forget the other, but That company was owned by a then friend's dad. This was 43 years ago. Just Saying ! P.S. I enjoy your videos. Thank you for making them!
I'd say that it's dangerous to croudfund any engineering endeavour unless you know exactly what you're building, how it's going to be built, with minimal unknowns. This is why we see other things like software struggling. People don't realize that there are things that we don't know that we don't know and it directly impacts everything about a product. Not just cost, but timeline, design, and required resourcing at the time, forget macro-economic conditions.
Plenty of stuff is crowd funded at the start. The difference here is the crowd is the general public. I think this is a bad investment but I don't think there's anything nefarious or reckless in this offering
It would make sense to use the scotch yoke in an opposed cylinder design to get around some of the strength issues the yoke has. Also, a plain rotational bearing has the same sliding friction as a linear sliding bearing (apart from the direction reversal). Making it work efficiently is just a matter of getting the fluid dynamics of the lubrication right. They make it work for piston rings.
Lubrication nowadays involves much more than just the fluid and basic surface treatments. There are nanoparticles for coatings, solid lubricants, electromagnetism, all sorts of bizarre alloys and ceramics, self-lubrication, ... (search for anything about tribology for more info) but the technology used in mass production is still lagging behind.
@@panvomacka9079 Modifying the Scotch Yoke in order to improve its problems with friction and structural issues seems to be more important than this. For example the inner slider could use a gear that rolls over a "serrated" surface and its shape could be slightly elliptical so it only touches one side at any moment. Another example is the article "Design of Scotch yoke mechanisms with improved driving dynamics" which proposes the use of springs to regularize the input torque.
The Scotch yoke actually tends to _degrade_ efficiency in practice. Since the piston spends more time being near TDC, and the sliding motion between the yoke and guide, more energy is lost as heat.
To have no side loading, there would have to be another sliding guide below the crankshaft for the piston assembly to slide in which means even MORE friction
Yes it seems that triangle would otherwise rock x degrees if it wasn't supported in some sort of guide... If the connection to the piston is solid, to keep the triangle moving I a vertical plane, rather than the usual wrist pin, seems there would be rotational forces there, that would end up cracking the connection to the piston... unless it's heavily reinforced, but that would be more reciprocating weight....
1:49 It's still at an angle, it's still trying to "flip" the rod or tilt it to one side. you talk about the friction losses from the first engine, but what about that block trying to slide around inside the rod
I love this guy. I love that he spent time explaining to people the realities of developing an engine as a segue from his analysis on the engine. Such a great channel.
To mitigate the "small thin" section weakness, make the entire area ROUND. Not flat. A flat surface is more friction. You can make the shape using a cylinder all the way around, and this increase strength (since cylinders are stronger) and also less surface area contact yet same result.
What about adding multiple rollers to the top and bottom of the square part of the crankshaft journal and pressurizing oil the same way from the inside of the crank.
The main advantage I see with this design is balance and harmonics. Wear rates are very good on conventional piston engines that are 'properly' designed, due to advancements in materials/chemical engineering and manufacturing processes. Small engines are pushing loads of turbocharger boost and surviving (like AMG mercedes 4 cylinders), while milder engines (like Toyota's newer 2.5 liter) survive many miles of abuse and minimal maintenance.
Having watched 25mm thick steel rip like tissue paper, as well of having connecting rods blast new channels through engine blocks, I would suggest that scotch yokes remain with the early low power toys of yester years.
I always love your work, and great job as always. I especially love your break down of what is and isn't a scam because of just how bad it really is out here. Free idea for the next April Fool's day: explain breathing and then add blinking so people know how to do both at the same time.
I'm wondering if the rectangular slot is a modeling simplification, or if changing it to rounded ends (like a pill) would make the slot a bit stronger x) Unless the square bit slams into the slot's sides and a flat surface is desirable ?
Hater's gonna hate. You don't have to explain yourself. Thank you for the interesting and informative videos. The vast majority of us appreciate you sharing your knowledge and cool new technologies.
The combustion forcing the piston to one side of the cilinder will not be completely gone on this desighn. The "rod" is still only supported by one side when combustion pushes down on it, so there is going to still be some torke generated.
Where can I give you 100 thumbs up? In all seriousness, this video is great. Many people don't understand the complexities of developing anything. This is sometimes a failure of the press. On a related note, I would like your take on things like Liquidpiston or the Omega 1 engine. Purely from a technical standpoint.
The force angle is there on both types. If you take for example the moment when the crank shaft is at 90°, the little square which the force acts upon is not directly below the center of force. Therefore the twisting force still remains. This does not solve anything.
8:43 i knew this would be Alfadan's new engine tech since back then they said "we revolutionized the connecting rod" while they where working with Mahle but not showing anything to it before they get enough validation data just the "soon TM" glad to know this thing was still trucking along and thanks for the follow up mate!
could you dive deeper into the Taurozzi Engine, aka the Pendulum Engine? It seems to solve the piston friction alltogether, but at the cost of more mass on piston rods, altough the pistons themselves are much lighter.
Neat theory, but more moving parts = more things that could break. I also think that would add a lot of weight the rotating assembly. Not to mention packaging inside the block, I don’t think a rod that wide would clear the bottom side of sleeve or other parts of the block when piston is at TDC, at least on a larger stroke engine. I could see the square inside the rod wearing out very quickly as well.
Rotating crank journals are still sliding friction, they just are sliding in a circle. The reason early designs failed is their rods sliding surface wasn't being pressure oiled, as modern cranks and thus rod journals are. Lastly, we could build these and eliminate PRIMARY IMBALANCES if we combined this design in a BOXER engine. You're welcome ;)
Just from looking at this configuration, it apears to me that there is still a torque force where the piston and con rod join, since there is only resistance on one side of the slot; probably mitigated by constraint of the cylinder barrel, but that would then create piston:cylinder friction again... I'd also think the sliding friction under load might be a great deal more difficult to overcome than it it seems... Obviously thpugh, this is just eyeball impressions, so could be completely wrong. 🤷♂️
I am glad you present these alternative technologies. We have to accept that most of them won't pan out. You can't be an entrepreneur without having unreasonable faith in your product. Sometimes it works, mostly it doesn't. Either way, it is nice to see what is out there.
Hey, I think you should analyze and do a video about the Commer ts3 Engine, a really unique op two stroke diesel like no other, and talk about the benefits and drawbacks about its design!
In large diesel engines, side-loading on the piston walls is eliminated by having a straight intermediate shaft between the piston and crank, which allows the side-loading to be shifted to a separate bearing set. Can't do that on small engines since it adds a bit more than a piston stroke length to total crank case height.
Nice video as always, keep it up and don't mind the people that complain ilogically after barely understanding what your videos explain, and for free. Someones do only see what they want. Thanks for the content.
I have an early Bosch power saw that uses that arrangement to drive the blade back & forth. It was my granddads then my dad's now I've got it ! Still working perfectly. They definitely don't make them to last like back then, has to be around 90 years young.
I remember back in the day, the original Alfa Romeo GTA from the 1960s and 1970s had a sliding block rear end (might have be an option for racing use) to help locate the rear axle. From my understanding wear and maintenance issues were the main problems. This video reminded me of that setup.
A partial solution is to make this engine a boxer design, thus, the surface in the bottom of the rod & piston will no longer be thin. This doesn’t resolve the sliding motion, but it does solve the strength issue. The triangle is the strongest shape and this would make a diamond shape piston rod combo.
Give an engine more points of possible failure, it will possibly fail more frequently. Always interesting to see anything innovating, whether it's old or new, revisiting them is always a good experience! Especially with evolving machining and tech!
If they claim that they have solved the fundamental problems in the design, and it turns out later that they lied and they haven't, it's a scam by definition. Only time will tell.
With this design the top of the piston design can change 4 valve per cylinder = the top of the piston should be rectangular with round corners What u think ? Make a 4 cylinder motorcycle engine
There will be a side friction anyway, not on cylinder walls but on "rod" outer walls. It will be necessary to prevent a rod-cylinder assembly from tilting. Bourke cross was preventing that by placing two cylindrs in oposing positions.
Wow! I actually dropped an email 2 years ago or so to D4A to cover balance in case a Scotch yoke would be used exactly after watching the Alfadan video. No idea if it had any impact but still nice that it's actually here ;-)
Besides increased friction, If part of an inline 2,3 or 4 there is probably going to be a weakness on the bottom of the slide when pulled down when the other cylinders fire pulling it down. It would have to be a lot thicker at least... then you end up with a lot more mass than a conventional piston and conrod design... which brings its own performance hitting issues. I'm not seeing many advantages... and far more disadvantages.
I think you would still get the cylinder wear/friction problem because the force of the piston will still be sideways. Think of it like holding a long 2 by 4 horizontally against your abs, and trying to push on a box with one end. The force will still be transfered at the angle. It doesn't matter what you do in-between.
what I love is all the people WITHOUT engineering degrees or knowledge in the comments of this channel "I dont think it's worth doing because blah blah blah" "I see problems with blah blah blah, conventional engines don't have that" "they'd have to blah blah blah before they could blah blah" THIS IS THE POINT OF RESEARCH AND DEV people. This is what engineers do. This is WHY people invest in these projects. It's always a risk, but it could pan out very well. Even the engineers don't know how it's going to work until you actually start trying to make it. You can't buy parts for something that doesn't exist. You can't refine something that doesn't exist. You can't troubleshoot something that doesn't exist. You have to design and machine EVERYTHING yourself. The reciprocating 4 stroke engine has been in CONSTANT development for over 100 years by a TON of manufacturers and designers. And even then it took a LONG time to work out problems like head gasket sealing. For a long time in the world of cars it was just accepted that head gaskets had to be resealed all the time. Early race cars often didn't even finish because they couldn't seal the head properly for long. There's a reason they work so well now and it's not that the design was the absolute best it could have been out of the box. If you're trying to compare almost any new design to the reliability, ease of maintenance, cost, efficiency, size, etc. of something that has had literally lifetimes of time invested into it and hundreds of billions of dollars, OF COURSE it's going to come up short initially. How is that so hard to see? It's the same people who said electric cars would never venture out of the city, and just look at them now. Jeez you people are sooo unimaginative and stuck in a box. And in a world where more is possible than ever lol, how does that work? Maybe open your minds and use your brains and you could actually help with some of these things instead of just naysaying
The wrist pin friction losses are just moved to the sliding square and the piston is obviously still loaded at an angle
Yeah i was thinking the same thing
Yes I see a lot friction there.
Would that sliding square be set in roller bearings, both top and bottom?
there is also a lot more weight.
@@rob5944 Even if, that would add more moving parts and reliability would probably suffer.
It can be a balance king but at the same time it become friction king. The contact surface is enormous
Large friction surface means lower friction!
@@stianmathisen4284explain please
@@stianmathisen4284 most of the surfaces in an engine never contact one another, they ride on a thin film of oil and any amount of metal-to-metal contact should be considered a mechanical failure. larger contact surfaces = way more oil shear forces = more losses. the main reason modern car engines are moving to thinner and thinner oils is because the engine oil viscosity contributes a huge portion of the total frictional losses
Why not put four bearings, one at each corner of the slider. That would eliminate the sliding friction.
The contact surface is smaller. 2-times diameter vs 3.1415926535... times
The sliding box section of the yoke design would make lubrication a lot more difficult to achieve effectively than with standard plain bearings on a normal crank pin.
Mitigation through soaking the crank in the oil sump halfway or more? Yes more detergent and stringent oil change intervals I believe
as a new comer marine engineer cadet, i have to say that the sliders that are being used on the 2 stroke low rpm diesel engines, are made of white metals, that are cheap and are the first to wear out, so damaging of the engine can be avoided. In those engines are vertical, but yoke sliders are on the side, something that will incise friction and wearing out. Because of that i am very interested to see with what they came out to stope that problem.
Not really, it would be feeding oil to the crank and thus the square itself through feed holes, exactly like normal cranks. And voila. Have it squirt oil just before and after the lead and end corners of each slide surface of the square, the same way we use piston skirt squirters. Just have it squirt the slides instead. Bam done.
The early Scot design probably only relied on paddle oiling like push mowers so it's no wonder it failed.
@@ShogunAutoworks it slows the wear out, but yes, if it is lubricated properly, then the life spend will be increased to that of a piston' s spring, or even more then that.
There could be needle bearings the same that are used in some high horsepower cam applications. However, there could be a round design instead of a square crank design.
There is still significant friction against the cylinder of the scotch yoke design: the off-centre force from the crank pin on the yoke causes a torque, just like in the connecting rod, which in turn torques the piston inside the cylinder. The force on the cylinder wall can be reduced by increasing the piston length, similar to how the lateral forces are reduced by lengthening the connecting rod.
No , the short edges of the scotch yoke's "square" run up and down linear bearings ( 9:40 648 & 650 in the diagram are bearings) in the crankcase walls. This eliminates side loads on the piston. i.e. The square also acts as a crosshead , as used in steam engines and large (ship size) diesels
For some reason most commenters fail to understand this
@@paulgee-i7j Ok, so they just shifted the uneven force and friction from the cylinder wall to the crank case wall. My point still stands.
It would probably not be a 1 cylinder engine.
I think you are missing the fact that the off-axis force still exists. So you will need restraint against rotating of the yoke due to the moment (torque).
@@paulgee-i7j Got it, so you have more reciprocating sliding surfaces and more reciprocating mass. You also have much more difficulty in maintaining tolerances which is why such designs have only been used commercially in low speed applications such as diesel ship engines. You just moved the problem (which has long ago been solved) to a more problematic location. YAY! I love designs that rattle themselves apart due to problematic tolerancing requirements!
I am a pilot. Although I spent most of my career flying jets, perhaps my favorite piston aircraft engine is the Lycoming IO-360. It is a 6 liter, 4 cylinder engine. How do they manage to make a smooth 4 cylinder engine that big? It's an air cooled boxer. The secondary balance problem was solved a long time ago, 23 million Volkswagen Beetles can't be wrong.
boxers are very suitable for larger displacement due to their inherent good balance. vw beetles were built to spec so are not the pinnacle of engineering, just good enough. a boxer 6 is even better than a boxer 4, ie porsche.
lol i was thinking the same thing, this design but in boxer engine would get rid of many problems he talks about, and if you make lets say, a 8 cyl boxer, with two pistons per rod assembly, you get rid of the weakness in the bottom rod cap
@@daos3300 porsche makes flat sixes, not boxer sixes.
@@midnight.a3 how so?
@@midnight.a3 nope
You not only have sliding friction but also every moment of movement places a different direction of sheering force on that slot as you convert circular motion into lateral motion.
Scotch yoke sounds like a British breakfast dish.
Great work. Love this channel.
😂😂😂👍🍳
It does.
Something grey, disgusting and that gives you heart attacks.
It's actually the non-rotating centre of a Scotch Egg 🤣
Deep fried scotch egg made out of mars bars and heroin... probably
1.7m investment, nothing to show, the only 2 employees taking a 100K a year salary. No seems legit.
We had a horizontally-opposed Scotch-yoke engine designed three decades ago. Each piston was double-ended (you still need to keep that yoke from moving, there _are_ side forces!) with the yoke in the middle. We never got around to building it, but in my retirement I may do so. Gotta make it a four to keep the balance even close enough to live with!
Use rails on the right+left of the yoke.
Could it be possible to use gears to increase the strength and reduce sliding friction?
What engine was that? I've only heard of a 2 stroke design and that it never made mass production.
Bourke engine, look it up.
@@klausbrinck2137 And it's added friction...
That whole thing about no sideloading on the piston is unfortunately not true in the configuration that was shown in all the animations. Adding linear bearings to keep the yoke from moving sideways would take out a lot of that, but it would add friction at yet another point.
It's a case of saving friction in one place and loosing it in three others. So sorry, but I can't see how this would be able to revolutionize engine design. People have tried it before, and will try again as everyone is certain that no one else understands just how great their particular idea is.
And there's nothing wrong with people trying to refine ideas, but it become stupid when you have to ignore science for your idea to make sense.
Thanks! As always you manage to explain things in a manner that it makes them look simple even if I know they are not.
The best automotive channel from my point of view.
Thank you so much for your support. I sincerely appreciate it.
Scotch yoke engines make more sense as a boxer engine
I remember reading a article on how it would change engines forever and that was 20years ago still waiting.
As mentioned in the video, there are still inherit issues with the Scotch/Yoke engine that is still keeping it in engineering development. Until then, a conventional piston mechanism is still the preferred choice for mass production and applications.
Not a boxer, you mean a flat engine - a boxer, by definition, needs to have separate rods
It’s vapour ware.
I read about the scotch yoke in 1974, still waiting. 😅
The Scotch crank has been arround for ages . It's ONLY advantage is that the piston moves sinusoidaly . Greater reciprocating mas more sliding friction , a total non starter that should remain a historic curiosity .
Have you heard of the Wankel rotary engine it is cool and people are working on making it more efficient with better seals
The yoke needs a tail guiding section below the connection to the crank to overcome piston ossilations within the bore from the forces of power stroke and compression strokes. The line of force moves from one side of the yoke/crank connection on every cycle.
The yoke runs on rails on its left and right (not shown in the animations here)...
It's called a crosshead but yeah
Came here to write a similar thought. The forces on that large "see saw" will cause huge friction on the piston to bore area. Adding more stabilisation to counter that just makes the friction elsewhere increase .
Another piston seems like the ideal "stabilizer".... it's other shortcomings, not withstanding...
@@jamesgeorge4874 an additional piston is probably best, a flat 8 seems like the most logical configuration
do you have any concrete evidence that their claims of the superiority of their engine is not baseless, and they aren't just sitting around twiddling their thumbs saying "working on it" while drawing a wage until the invested money runs out?
I don't and neither does anyone but society is built on the concept of innocent until proven guilty. No one has said proof for thousands of different companies but we can't go arresting based on assumptions without proof. Ps it goes the other way too. Do you have concrete evidence they're doing what you claim? Or any other company. You also don't have concrete evidence that I'm not a thief but you can't barge into my house because you can't get a search warrant based on a hunch that I'm a thief.
That's the way most startups work. They have an idea and maybe a few patents, and they burn through capital until they have something worth selling. It's a speculative investment; most of them fail but some make it big or at least get bought out profitably. If you don't like the idea, don't invest in them.
im not convinced the complexity of the sliding friction interface is worth a minor improvement in vibrations.
You're underestimating harmonics and balance
The most important part is getting rid of the far more severe sliding-friction in the cylinder/piston -interface... High combustion temperatures let metals get soft, and ease the destructive effects of sliding friction. Friction doesn´t come from nowhere, it simply leaves the cylinder, and goes somewhere, where the situation is far more under control, cause it´s cooler.
You get the benefit of longer dwell at tdc and a few other things on top of that.
Scotch yoke engines aren't exactly a new thought, the first ones built were the Bourke engines iirc.
They're quite interesting, and it's without doubt a feasible concept. Iirc some larger companies experimented with some such rather recently because the longer dwell time/slower movement around TDC was supposed to have advantages for HCCI engines or something like that.
if it was worth it, it would be used all over the place
The slider bracket would have to have a guiding groove andthe guide square have guide nub. Starting this would require a starter on the crank and timed firing. It seems rather extensive withmore draw backs for mass production. The lower crank case would need testing as well
Funny in 1976 my father and I built a 2 cylinder apposed Brouke scotch yoke engine. We used a roller bearing on the crankshaft, but on our first crankshaft the rod journal was to small and it sheared off. Second try we used a Kawasaki 100cc crankshaft. I believe that an apposed 4 cylinder may solve some of the balance issues. We were able to get 10,000 rpm underload but were unable to spin it faster due to it having a carborator and a distributer out of a 1960's VW. Using modern direct injection and ignition this may actually work.
if you like new engine ideas, you may like the liquid piston engine. It seems to have a lot of potential, by being able to run in a variety of fuels, with high efficiency, and being simple and light weight. There is not much videos about it, so if you find it interesting, you could make a video about this engine, and at the same time help the engineers by making their job known.
It does sound interesting, but at the same time the company and people there have too many... "questionable" stuff behind them. I'd love to be proven wrong, but there're too many signs that it's an intentional scam, just to grab investors' money.
LP is just another crap ass rotary engine with high SA/vol and low efficiency. theres a reason they havent published any efficiency numbers yet
@@dirtyclanner2250 they are developing the engine from 2004, with the final design been made in 2016. From then, they are involving it, trying to make it more efficient and more powerful. They have a small museum with their previous designs and fully workable prototypes, and in their website, their looking for new engineers, so calling it a scam is a huge claim for which there are no evidences.
@@reedhanson5945 they have relish. It is all in their website. Also don't say that something is a crap before it get tested. The LP engine doesn't need more lubrication oil then a usual engine, because the friction that is experiencing is mostly rolling friction.
The LP engine would be great for small aircraft but I am skeptical if they will ever make an engine that does not need overhauled frequently. The Achilles heel of the design is the seals, not at the tip like on a normal rotary but on the sides of the rotor.
Fascinating that the source of secondary imbalances in a standard layout are clearly visible as the two models reciprocate.
nice scotch yoke, next: geared piston
Why bother with geared pistons. Wankel engines is where it's @ m8!
@@markusluftner8418 a Wankel is basically 3 geared pistons in one
@@hansdietrich83 No, its' 3 very inefficient geared pistons in one.
@@markusluftner8418 So 3 geared pistons in one, then.
@@Ijusthopeitsquick no 3 oilfillercaps in 1 scavege pump
I think the Scotch yoke rod should slide between rails, to keep it straight and in linear motion. Now the force of combustion will try to tilt it and the piston, which is much worse than pushing into the cilinder wall. Great idea though!
Yes, real Scotch yoke engines do have rails to constrain the "big end" of the yoke, which are omitted in this video. They are visible in the small model engines shown in this video, and in the Alfadan patent drawings also shown in this video.
I see a torque at the piston in that configuration. Much more than in the traditional design. I would guess that this would greatly increase wear an the potential of engine failure. In the traditional design, the piston is pushed against one side. But in the here presented design, the piston will get tilted. Seems like a bigger problem to me.
Needs a cross head to control the rotation of the yoke.
Yup, not only that but you might need a longer piston head to reduce the moment-induced forces at the corners, increasing the contact area of the piston walls and increasing friction.
Then there's the arm which would probably need to be much wider to survive the bending moment without fatiguing.
Then he also says there are fewer parts because there's no hinge between the head and the arm, conveniently forgetting that those extra parts have just been shifted down to the sliding block connection.
In general mechanical engineers like to say that they prefer rotation over sliding wherever possible for reliability. There's so many practical reasons why this theoretically better engine just isn't better. Engine builders haven't just been ignorant this whole time, they've converged on the conventional design for good reasons.
@@excrubulent In addition to that, bearings, or anything round, is easier and cheaper to manufacture.
Sorry for spelling errors, i usually speak german ^^'
As a mechanical engineer I can say this channel is top notch. Those animations just incredible. Visualization is the key to teaching. Amazing work!!!
as a mechanical engineer you should recognise this design doesn't remove the piston axial torque he mentions initially
@@darysparta9676 first of all "piston axial torque" isn't a thing. Not sure what you are referring to. Regardless he said the secondary forces are "much less pronounced". He did not say anything was eliminated.
It seems one would want roller bearings inside the slot. Is there a hidden problem with that? And maybe a hydraulic mechanism to keep contact with both sides of the slot (kind of like hydraulic lifters) as it wears?
This does nothing to reduce piston side forces, they're still there just the same as the geometry is still the same. It does dramatically increase reciprocating mass though, so I guess that a plus? Quite literally the only 'benefit' I can see here is better balance, but there's much better ways to resolve that problem.
Just looking at the scotch yoke design, I would expect it to be a better proposition in horizontally opposed engines, simply becaues each cylinder will support the straight movement of the yoke assembly, also able to optimise the strength of the yoke on both thrust surfaces without adding extra material. I would also expect this layout to reduce any balance issues.
Surprised the likes of Porsche and BMW (Motorcycles) havent tried this in their boxer engines.
Boxer engines are a subset of horizontally opposed engines that don't use the same crankshaft pin so wouldn't work like you say. If I'm understanding what you're saying correctly. This would work on some flat engines, but not on boxer flat engines which are what Porsche and Subaru use.
Very interesting. So Alfadan didn't actually "reinvent the connecting rod" (their words not the video presenter's), they refined an existing design. I hope they succeed in bringing their technology to market.
They did?? Where? We all would love to actually see something
@@nenume00 Alfadan is a scum 100%. They just want investors to give them money. The owner will take all those money and deliver nothing. The money will go to his own pocket to finance his car, his boat, his mistress etc. Thus the mentioned in marketing material engine will never happen. Never.
Scotch yoke.... I'm in Perth Western Australia and two different local companies made versions of an engine known as the Bourke Engine (USA 1960's). Bottom line frictional losses were too high, as was wear. LOL. I typed this as your video started... You covered most of it in your video. However....
One was Sarich Technologies...Circa 1987. I forget the other, but That company was owned by a then friend's dad. This was 43 years ago. Just Saying ! P.S. I enjoy your videos. Thank you for making them!
Hello Neighbour- keep cool
I'll never tire of your presentation style, broad vocabulary, and ability to convey complex concepts. So cool! Bravo!
I'd say that it's dangerous to croudfund any engineering endeavour unless you know exactly what you're building, how it's going to be built, with minimal unknowns. This is why we see other things like software struggling. People don't realize that there are things that we don't know that we don't know and it directly impacts everything about a product. Not just cost, but timeline, design, and required resourcing at the time, forget macro-economic conditions.
Exactly!
Plenty of stuff is crowd funded at the start. The difference here is the crowd is the general public. I think this is a bad investment but I don't think there's anything nefarious or reckless in this offering
@@d4a USE WHEELS!
It would make sense to use the scotch yoke in an opposed cylinder design to get around some of the strength issues the yoke has.
Also, a plain rotational bearing has the same sliding friction as a linear sliding bearing (apart from the direction reversal). Making it work efficiently is just a matter of getting the fluid dynamics of the lubrication right.
They make it work for piston rings.
Lubrication nowadays involves much more than just the fluid and basic surface treatments. There are nanoparticles for coatings, solid lubricants, electromagnetism, all sorts of bizarre alloys and ceramics, self-lubrication, ... (search for anything about tribology for more info) but the technology used in mass production is still lagging behind.
@@vitordelima don't believe the spiel on an oil bottle , Castrol Magnetec 🙄
Indeed, but opposed cylinders mean 2 heads, which already complicates the engine a lot, so it could ruin the "game changer" potential of the engine
@@panvomacka9079 Modifying the Scotch Yoke in order to improve its problems with friction and structural issues seems to be more important than this. For example the inner slider could use a gear that rolls over a "serrated" surface and its shape could be slightly elliptical so it only touches one side at any moment. Another example is the article "Design of Scotch yoke mechanisms with improved driving dynamics" which proposes the use of springs to regularize the input torque.
Someone has never heard of a hydrodynamic wedge...
The Scotch yoke actually tends to _degrade_ efficiency in practice. Since the piston spends more time being near TDC, and the sliding motion between the yoke and guide, more energy is lost as heat.
The way you explained scam and what is not scam was amazing. I love you! Lmao 😂🤣😂🤣
To have no side loading, there would have to be another sliding guide below the crankshaft for the piston assembly to slide in which means even MORE friction
Yes it seems that triangle would otherwise rock x degrees if it wasn't supported in some sort of guide...
If the connection to the piston is solid, to keep the triangle moving I a vertical plane, rather than the usual wrist pin, seems there would be rotational forces there, that would end up cracking the connection to the piston... unless it's heavily reinforced, but that would be more reciprocating weight....
1:49 It's still at an angle, it's still trying to "flip" the rod or tilt it to one side. you talk about the friction losses from the first engine, but what about that block trying to slide around inside the rod
I feel like if we had the technology to mitigate the friction from this thing we would already have better engines at that point lol
That Scotch Yoke design will be forcing the piston to rock in the cyclinder, thus trying to grip it.
A lot
I love this guy. I love that he spent time explaining to people the realities of developing an engine as a segue from his analysis on the engine. Such a great channel.
To mitigate the "small thin" section weakness, make the entire area ROUND. Not flat. A flat surface is more friction. You can make the shape using a cylinder all the way around, and this increase strength (since cylinders are stronger) and also less surface area contact yet same result.
What about adding multiple rollers to the top and bottom of the square part of the crankshaft journal and pressurizing oil the same way from the inside of the crank.
The main advantage I see with this design is balance and harmonics. Wear rates are very good on conventional piston engines that are 'properly' designed, due to advancements in materials/chemical engineering and manufacturing processes. Small engines are pushing loads of turbocharger boost and surviving (like AMG mercedes 4 cylinders), while milder engines (like Toyota's newer 2.5 liter) survive many miles of abuse and minimal maintenance.
i have one downside, friction, there are two extra friction surfaces where oil can't realy come without verry complicated oil channels
I can't believe this man just had to explain to people what scam means
Is there a good reason the scotch yoke inside block cant be a circle? Rolling inside the shafts block inside of sliding?
Having watched 25mm thick steel rip like tissue paper, as well of having connecting rods blast new channels through engine blocks, I would suggest that scotch yokes remain with the early low power toys of yester years.
7:57 correction: the piston rings are sliding the walls, and sometimes the piston skirts do that too
Gives a whole new meaning to forcing a square peg in a round hole
what if we replace this sliding block with a loosely spinning wheel? would that reduce the friction?
I love it when armchair internet engineers get triggered by an engine design outside the norm
Friction: Im gonna have to stop you right there
I always love your work, and great job as always. I especially love your break down of what is and isn't a scam because of just how bad it really is out here.
Free idea for the next April Fool's day: explain breathing and then add blinking so people know how to do both at the same time.
There is force pushing the piston to both sides of the cylinder depending of the offset of the sliding part to the vertical axis of the rod.
I'm wondering if the rectangular slot is a modeling simplification, or if changing it to rounded ends (like a pill) would make the slot a bit stronger x)
Unless the square bit slams into the slot's sides and a flat surface is desirable ?
The ends of the slot aren't contacted and are purely structural.
@@TheShamefurDispray okay, thanks !
Wow brate, the knowledge and the visuals, very very informative and well put together! Svaka čast!
Maybe some kind of needle/roller bearing setup in the rod big end would be the way to go?
I’m excited to see this! I’d love to see you cover other alternatives to traditional engine configurations.
All I see is more weight, more friction, more complexity, lubrication problems, and maaaaaayyyyyyybe a slight increase in power
Hater's gonna hate. You don't have to explain yourself. Thank you for the interesting and informative videos. The vast majority of us appreciate you sharing your knowledge and cool new technologies.
The combustion forcing the piston to one side of the cilinder will not be completely gone on this desighn. The "rod" is still only supported by one side when combustion pushes down on it, so there is going to still be some torke generated.
Became a financial advice video from an engineering video 😂😂
I need a car guy friend like you! I love the way you talk and think and disect everything to do with cars! Good video as always!
Where can I give you 100 thumbs up? In all seriousness, this video is great. Many people don't understand the complexities of developing anything. This is sometimes a failure of the press.
On a related note, I would like your take on things like Liquidpiston or the Omega 1 engine. Purely from a technical standpoint.
The force angle is there on both types. If you take for example the moment when the crank shaft is at 90°, the little square which the force acts upon is not directly below the center of force. Therefore the twisting force still remains. This does not solve anything.
8:43 i knew this would be Alfadan's new engine tech since back then they said "we revolutionized the connecting rod" while they where working with Mahle but not showing anything to it before they get enough validation data just the "soon TM" glad to know this thing was still trucking along and thanks for the follow up mate!
could you dive deeper into the Taurozzi Engine, aka the Pendulum Engine? It seems to solve the piston friction alltogether, but at the cost of more mass on piston rods, altough the pistons themselves are much lighter.
Neat theory, but more moving parts = more things that could break. I also think that would add a lot of weight the rotating assembly. Not to mention packaging inside the block, I don’t think a rod that wide would clear the bottom side of sleeve or other parts of the block when piston is at TDC, at least on a larger stroke engine. I could see the square inside the rod wearing out very quickly as well.
Rotating crank journals are still sliding friction, they just are sliding in a circle. The reason early designs failed is their rods sliding surface wasn't being pressure oiled, as modern cranks and thus rod journals are.
Lastly, we could build these and eliminate PRIMARY IMBALANCES if we combined this design in a BOXER engine.
You're welcome ;)
Just from looking at this configuration, it apears to me that there is still a torque force where the piston and con rod join, since there is only resistance on one side of the slot; probably mitigated by constraint of the cylinder barrel, but that would then create piston:cylinder friction again... I'd also think the sliding friction under load might be a great deal more difficult to overcome than it it seems... Obviously thpugh, this is just eyeball impressions, so could be completely wrong. 🤷♂️
If only someone redefined rotary engine to work perfectly with no flaws
The flaws in all engines is what makes them so interesting.
There is no absolute perfection; only levels of staving off inevitable impending failure.
I am glad you present these alternative technologies. We have to accept that most of them won't pan out. You can't be an entrepreneur without having unreasonable faith in your product. Sometimes it works, mostly it doesn't. Either way, it is nice to see what is out there.
Hey, I think you should analyze and do a video about the Commer ts3 Engine, a really unique op two stroke diesel like no other, and talk about the benefits and drawbacks about its design!
Always happy to see you upload. I always learn so much from your videos. Great job!
In large diesel engines, side-loading on the piston walls is eliminated by having a straight intermediate shaft between the piston and crank, which allows the side-loading to be shifted to a separate bearing set. Can't do that on small engines since it adds a bit more than a piston stroke length to total crank case height.
This is called a cross head, also seen on steam engines where it is mandatory in most cases because the cylinder is double acting.
Nice video as always, keep it up and don't mind the people that complain ilogically after barely understanding what your videos explain, and for free. Someones do only see what they want. Thanks for the content.
it feels illegal to be this early
You'll be arrested and jailed unless you deposit some bitcoin to a suspicious wallet 😂😂😂
I have an early Bosch power saw that uses that arrangement to drive the blade back & forth. It was my granddads then my dad's now I've got it ! Still working perfectly. They definitely don't make them to last like back then, has to be around 90 years young.
way more friction points .This is in the same category with the rotary engine.
And side thrust on the bore...
@@jimrobcoyle that is in the first revs lol
Thanks for the really bad explaination on what investments are, and what a scam isn't.
I remember back in the day, the original Alfa Romeo GTA from the 1960s and 1970s had a sliding block rear end (might have be an option for racing use) to help locate the rear axle. From my understanding wear and maintenance issues were the main problems. This video reminded me of that setup.
This video is wrong in every way.......
17:15 - My favourite quote yet! *"But of course, knowing that..."*
This guy lost all engineering credibility when he backed Alfascam.
This is brilliant. Less the additional material needed to make a triangle versus a rod.
A boxer configuration where 2 cylinders share the same rod will considerably improve the rigidity of the lower part of the rod.
A partial solution is to make this engine a boxer design, thus, the surface in the bottom of the rod & piston will no longer be thin. This doesn’t resolve the sliding motion, but it does solve the strength issue. The triangle is the strongest shape and this would make a diamond shape piston rod combo.
Scotch yokes are widely used in mechanical engineering, maybe there is something that uses it under similar conditions already.
Give an engine more points of possible failure, it will possibly fail more frequently. Always interesting to see anything innovating, whether it's old or new, revisiting them is always a good experience! Especially with evolving machining and tech!
This was all done many years ago in the Bourke engine 1930's
How about a Scotch yoke boxer?
Seems rollers could alleviate the friction issue. Very interesting video! Complements!
Thanks for the video... Please do a video on roller rod bearings like on the honda s600... thanks
A flat 8 is balanced perfectly and gives the smoothest power.
If they claim that they have solved the fundamental problems in the design, and it turns out later that they lied and they haven't, it's a scam by definition. Only time will tell.
With this design the top of the piston design can change
4 valve per cylinder = the top of the piston should be rectangular with round corners
What u think ?
Make a 4 cylinder motorcycle engine
There will be a side friction anyway, not on cylinder walls but on "rod" outer walls. It will be necessary to prevent a rod-cylinder assembly from tilting. Bourke cross was preventing that by placing two cylindrs in oposing positions.
that sliding contact has high friction what about that
Wow! I actually dropped an email 2 years ago or so to D4A to cover balance in case a Scotch yoke would be used exactly after watching the Alfadan video. No idea if it had any impact but still nice that it's actually here ;-)
What about friction in that sliding surface
What about watching the video?
Besides increased friction, If part of an inline 2,3 or 4 there is probably going to be a weakness on the bottom of the slide when pulled down when the other cylinders fire pulling it down. It would have to be a lot thicker at least... then you end up with a lot more mass than a conventional piston and conrod design... which brings its own performance hitting issues.
I'm not seeing many advantages... and far more disadvantages.
I think you would still get the cylinder wear/friction problem because the force of the piston will still be sideways. Think of it like holding a long 2 by 4 horizontally against your abs, and trying to push on a box with one end. The force will still be transfered at the angle. It doesn't matter what you do in-between.
Maybe so, but it would be fractions of the force of a conventional piston/rod/crank arrangement
what I love is all the people WITHOUT engineering degrees or knowledge in the comments of this channel "I dont think it's worth doing because blah blah blah" "I see problems with blah blah blah, conventional engines don't have that" "they'd have to blah blah blah before they could blah blah" THIS IS THE POINT OF RESEARCH AND DEV people. This is what engineers do. This is WHY people invest in these projects. It's always a risk, but it could pan out very well. Even the engineers don't know how it's going to work until you actually start trying to make it. You can't buy parts for something that doesn't exist. You can't refine something that doesn't exist. You can't troubleshoot something that doesn't exist. You have to design and machine EVERYTHING yourself. The reciprocating 4 stroke engine has been in CONSTANT development for over 100 years by a TON of manufacturers and designers. And even then it took a LONG time to work out problems like head gasket sealing. For a long time in the world of cars it was just accepted that head gaskets had to be resealed all the time. Early race cars often didn't even finish because they couldn't seal the head properly for long. There's a reason they work so well now and it's not that the design was the absolute best it could have been out of the box. If you're trying to compare almost any new design to the reliability, ease of maintenance, cost, efficiency, size, etc. of something that has had literally lifetimes of time invested into it and hundreds of billions of dollars, OF COURSE it's going to come up short initially. How is that so hard to see? It's the same people who said electric cars would never venture out of the city, and just look at them now. Jeez you people are sooo unimaginative and stuck in a box. And in a world where more is possible than ever lol, how does that work? Maybe open your minds and use your brains and you could actually help with some of these things instead of just naysaying
I agree with you on balance, however machining cost and wear are going to be an issue.