Question: What about either multiple air tanks or a multi-chambered tank with a system to switch from one chamber to the next as a way to keep a more consistent pressure throughout the run. Either a pressure regulated selector or a timed clockwork style of system to achieve the same result. Higher initial pressure would be required to see any real gain though. I think.
Tom's air engine project has been hands down my favourite home-made science video series to follow on TH-cam for years. This thing started as a curious fun project and is slowly turning into a slick usable design
I work in bottle engineering, and part of the test we perform on the samples we make is a burst test. A 300ml bottle for highly carbonated products if well blown, can easily reach up to 15bars before bursting (not that i would reccomend reaching that pressure, as we do it with a proper machine that uses water instead of air). A 1500/2000ml falls a bit short of 12bars. Anyway. Beware that by making the hole on the bottom of the bottle, you are definitely weakening the overall resistance of the base, i would try to pressurize the bottle by adding another valve to the cap instead. Keep up experimenting!
Just for the record in the water rocket community its well known that 120 psi is generally where these 2 liter bottles tend to explode. 100 psi is about the upper safe limit you would want to pressurize, 60 psi is almost entirely safe and 80psi is about the upper end of that. Though these are rough figures they should apply about the same. It's also worth noting, its generally not dangerous, just loud, its a little bit of thin plastic, the most it'll manage to do is scare you pretty badly. Unless it sends something flying somehow.
@@killingtimeitself You even try a SodaStream bottle? Not quite as light, but they can handle a LOT more pressure. I've had mine up to 175 psi(12 bar) with no issues... which sort of sucks because I was trying to pop it to scare somebody. I later watched a video from the good folks over at Beyond The Press who had one up around 25 bar(360 psi) before it burst with deformation appearing to occur somewhere near 20 bar(290 psi).
@@dw7444 i've seen wrapped and reinforced 2l (carbon fiber and kevlar iirc) that can do upwards of a thousand PSI, if you really wanted to maximize thats probably the way, though im sure that increases weight by a minimum of tenfold.
For people that don't like mixed unit conversations: 15bar = 218psi 12bar = 174psi 8.3bar = 120psi 6.9bar = 100psi 5.5bar = 80psi 4.1bar = 60psi And for people that haven't seen the metric light yet, 1bar = 1 atmosphere
I love seeing your creative approaches to optimizing something so small, the redesigns, and all the quasi-microscopic changes that go into yielding a slightly higher efficiency each revision. This is probably one of my favorite series!
Contrats on the video, the quality of your content is insane. As a mechanical engineering student, I realize the amount of hours you put into every single video is absolutely insane. Keep up the hard work! Well keep supporting!
Wow, the progression between all of your pneumatic engines is impressive. I love the simplicity of the mechanical feedback loops, they are so clever! Great videos as always Tom.
This was so incredibly cool. I love the graphs, the animations, the slow-mo, and the mechanical nature of your projects. I can't wait to see what comes next! This air piston series has been incredibly fun to watch so far.
I absolutely love this series. It is the definition of engineering. Literal years of R&D with many challenges and setbacks, the evolution of tools, equipment and materials used, all to improve design and efficiency. Keep up the great work Tom!
OH! I just read your bio and realized that you have a degree in aerospace engineering! I'm a highschool student and this series has really really interesting to me and actually kind of inspired me to look into and go after aerospace engineering once I graduate from high school and I didn't even realize that that's exactly the path that you took lol. Thank you for making this series, it's truly an inspiration to me and I would bet many many others as well.
5:45 you can make it so that TDC actually corresponds to high crank leverage angle by offsetting the cylinder from the crankshaft. Also do note that you can't really expand to atmospheric pressure because then exhaust would not occur. With a bottom discharge port design, the piston compresses the air on its way up, so higher expansion volume just means there's less intake resistance so bigger charge of air can enter. It makes it more powerful, not more efficient.
his seal design means there is little to no compression on the upwards stroke, though. exhaust at atmospheric pressure is done by the piston pushing the air down around it's sides and out as it moves upwards.
The 10x performance increase is just incredible. Optimisations like that are game changing. I bet you get approached by model airplane manufacturers and stuff soon if not already
@@Guenther-Eichingerinterestingly, that's not as crazy as it sounds. There are actual prototypes for air-powered cars that get similar efficiency to electric vehicles, and would potentially be cheaper and easier to build (not to mention much more encouragement friendly than lithium batteries)... One day you might actually see pneumatic cars on the road 😁
I wonder if having the cylinders offset would be a better option than having the curved rods. Traditional aircraft engines as well as BMW motorcycle engines (which I think were actually for aircraft originally) are also built with offset cylinders. With this miniature 3D printed design it might not even make a difference that could be measurable but might make for a good test. With the bore and especially the stroke, the change in curved rods to going with straight rods may show a difference in the torque as well as reduce the friction on the piston walls with the rods parallel to the pistons and cylinder walls and also reduce any air loss due to the pistons riding slightly cockeyed in the cylinders due to the rods being connected to the crankshaft at a small offset distance. Great work, Tom! I really like the content that you present on your channel.
It’s great when you release a new video on your air engines, it’s been really wonderful seeing the progress you’ve made over the years on this… great work Tom!
Absolutely tickled by the extremely elegant pneumatic manifolding and mechanical design going on here! One of the best explanations online about how a regulator works too. Great work!
Man, oh man, the sound of that 2cyl engine at the end was plucking at my heart strings, it sounds fantastic! Makes me want to build a desktop version just play with the throttle!
A simpler solution is to have 2 supply tanks, the later (and smaller) at a lower pressure to match the engine. This allows the main tank to be connected via the constant pressure valve. The run tank needs to be large enough to absorb the oscillations. The main tank can then be refilled on a long duty cycle of the supply compressor, starting just before the 2 tanks equalise and stopping at the max SWL of the main tank This system, (called cushioning), is used in high temperature heating systems. It allows the water to be held at a constant high pressure without boiling. The second tank has to be large enough to contain the volume increase of the water due to expansion. When the water is in a sealed loop, a primary tank is not always needed.
That air powered mini 1/2 VW is beautiful! Quite keeping to tradition of the home built aircraft and sounded stunning. When you pushed the air up and let it go, I was in awe. Keep it up!
it’s so weird yet amazing to have watched your videos for almost 6 years now and be able to watch as you spread your wings and share your creativity and intelligence with the world. you inspire an unimaginable amount of people with your videos and it’s absolutely beautiful to see your community grow! it’s you and a handful of other youtubers that are guiding the next generations into the world of engineering. thank you tom stanton for the amazing videos!
Tom, I am beyond impressed. I'm very proud of you and your resilience to the strange issues that came up, and am so glad that after each time you were seeking an answer or improvement and found it, every single time. You have to be one of my favorite TH-camrs and I love watching you and the things you create. Seriously, great job. Keep up the good work, and have fun designing the airplane for this badass engine!
You totally hit this one out of the park Tom, been following you for years and this series is an instant watch. The sound of the boxer air engine was insane and ik sure you can manage increase the efficiency of the single piston more. Would love to know the theoretical limit of it to compare as well!
Tom, you could improve efficiency even more by keeping the head design with no upper expansion area like you have now; and simply increasing the stroke volume to the point in which the expansion ratio is sufficient to your liking & DOESN'T have that high pressure delta when it goes to exhaust from the ports. And also finding a way to ensure that there is no compression stroke, only expansion, like a Miller-cycle on steroids. Not to mention the extra crank leverage you would receive with the stroke increase, would allow a larger, slower prop, etc. Please upvote this so Tom might see it, I am 100% sure I am correct about what I'm saying. Thanks.
I think the exhaust is the issue with the engine as you point out, there is a big compression stroke! if the expansion happens and the air in the cylinder is at 1atm at BDC then no air is going to leave the exhaust port, as the piston starts moving up there will be a tiny bit escape before the ports get covered but most of the air gets re-compressed and wastes most of the energy. the exhaust port should be in the piston and opened by the crank shaft, when the piston gets to the top it should close.
@@Hootie811 I think he is avoiding a compression stroke by having seals that don't work without pressure. When the valve opens and high pressure air flows in, the seal is pressed outwards against the cylinder walls. Then when the pressure is released, the seal springs back away from the wall, allowing the air to move past as the cylinder moves back up.
@@robertbackhaus8911 That's a neat design. Its funny how many actual engine concepts he manages to cover (by accident or not) just by developing these. I was wondering if he was going to try and implement some scavenging though I wouldn't see it being effective at all.
I was wondering whether higher engine rpm, from using a shorter stroke/bigger piston and a geared-down prop, would help efficiency. But I'm way over my head in the science!
@@robertbackhaus8911 I have also been thinking and testing of another way of doing this. You use a tilting piston that would seal just a slight bit before the valve opens, and the friction would also be *very* low, since the absolute only contact area that the piston has over the whole cylinder is just the seal, and that contact area is even less when it tilts. You would also reduce the amount of moving parts doing that aswell
Here is another point to increase your efficiency significantly: make the exhaust air leave the cylinder all the way up to the TDC. The reason your version with larger air volume was less efficient is because at the point where the exhaust openings were actually working the air pressure dropped to about ambient pressure so only little air could escape. Thus most of the air got compressed again by the piston going up, eating up all the energy gained on the way down. Of course this needs a timed valve (think combustion engine), which is a challenge on its own...😁
@@xmysef4920 There needs to be an excess in pressure, though. Otherwise the air won't get pushed out. I think the valve needs to controlled by the position of the piston: it needs to open when the piston is at the lowest position up until the piston reaches the highest point.
The engine already does this, you need to check his earlier videos. The rubber o-ring on the top of the piston deforms to seal the cylinder as the pressure increases on air inlet, and then returns to its original shape as the pressure decreases at the bottom of the stroke, so air can move around the piston as it moves up the cylinder, it isn't sealed during this part of the cycle. There is no compression on the upward stroke. Y'all are coming up with solutions to a problem that this design doesn't have.
This whole Pneumatic Engine series has been fantastic from start to finish and I feel like at this rate, you're going to come up with some inline 4 design that uses air-injection and electronic control to get the maximum possible efficiency!! I cannot wait to see where this goes, as this is super exciting work!!
What you see with the higher pressure and lower output is well known to pcp air rifle users as valve lock. There comes a point where the pressure in the tank is too high for the “hammer” or opening device to open the valve freely. From the looks of your graph, I think 85 psi may be the sweet spot
Right....much of the physics going on here are well known in the PCP community and surprisingly flat power curves can be achieved with a well tuned gun. It would also be beneficial for the air engine to use a two stage design much like the steam engines on ships where a 'Hi-pressure' cylinder then exhausts into a 'Lo-pressure' cylinder that's sized proportionally to efficiently use the lower input pressure. Steam has a much higher expansion ratio than compressed air so the benefits would be much less....still it seems wasteful to exhaust ANY pressure when the onboard supply is so limited. Entertaining experiments with the air engines Tom!
@@recoilrob324Or give it an exhaust manifold to get tome scavenging going, essentially create less than atmospheric pressure in the cylinder before the exhaust closes. Very much doable with flexible airhose on the twin cylinder. Might be interesting
I absolutely love this series. You're doing God's work. I bet you've single handedly inspired dozens of not hundreds of future mechanical and aerospace engineers.
@@ghostwhite1648This is false. You're referencing a meme called the "jet fuel hoax" which purports that jet engines use fuel to start an air compressor which then somehow produces the required power to continue running without fuel. Another variation of this meme says that 90% of the input of the engine is compressed air while only 10% is fuel. In fact this is a misinterpretation of the way that fuel/air mixture works. Combustion of kerosene in air is limited by the Oxygen content of Air, which is 20% O2 and 78% Nitrogen. By volume, only about 10% jet kerosene can be used before all the Oxygen is used up. The combustion heats the air which causes it to expand, which then drives the turbomachinery to compress more fresh air into the engine, this compressed air is then burned with fuel to repeat the cycle. So no, compressed air is not where the energy is coming from, it's where the energy from combustion is converted from chemical energy to heat energy and finally mechanical energy of expansion. Now let me blow your mind! This meme is ALSO a misrepresentation of the work of Viktor Schauberger, the Austrian scientist responsible for early experiments in vortex fluid dynamics. Viktor Schauberger discovered a mechanism to use hot, humid air and a cold sink, usually a cold water tank or body of water like a river, to rapidly compress ambient air to drive a turbine. This is using the opposite process of implosion rather than explosion used in combustion engines. Implosive engines still require a heat difference or humidity difference to operate because only systems that are not in thermodynamic equilibrium can perform mechanical work. The "repulsine" was Viktor's name for this type of cold implosion engine, and he was conscripted by Nazi Germany to construct prototypes for the Nazi war machine. It's unknown how successful this project was, but the principle behind the design is sound, as long as there is a cold reservoir sink available to dump the exhausted, condensed air. Without that temperature difference there is no source of energy to perform the mechanical work of compressing the air.
I was showing one of my friends this channel in my engineering class, and the professor overheard and came over and said he was a fan of the channel too. So congratulations on making content so good that teachers of the subject watch it for fun
Man, i love this series. Could you try to push the engines (even the old ones) to the breaking point? Does it give insight into the engines? No. Would it be cool? Yes.
I just got a 3d printer and have been printing for the last month party due to your videos. It's so much fun. I've even started designing my own models as well. Thanks Tom.
You could consider prototyping a version with an offset crankshaft. Like you showed at 6:28, you'd get a more favourable crank angle to make better use of the high pressure air. This would approximate an Atkinson-like cycle, except unlike a combustion engine compression losses aren't a thing.
I think you scrapped the larger expansion version a little too early. I'd come back to it and play around with cylinder offset, so the connecting rod is already past TDC when the air impulse comes in. I sure would like to see the results of that!
See: triple expansion steam engine. All ya gotta do is get the piston diameters matched to the previous stages exit air pressure & the efficiency goes way up.
This is such a cool project Tom! I had an Free flight air hog plane as a kid that had a pneumatic motor. Always thought it would be cool if you could make it R/C. Keep up the great work!
I wonder is a Radial engine more efficient than a conventional V Engine (If not wrong, Radial engine pretty much not used anymore after WW1, with the usage only being for legacy designs)
love the series, always gets me motivated to also try some air engine designs. For me with boxer engines having the connectingrods offset induced a lot of friction because of them wanting to spread and jamm. So offsetting the cylinders instead helped a lot although I always used a plastic crank and not even a circular one which probably amplifies the problem.
Awesome seeing an air engine again from you! Your videos on them are very interesting and are relaxing to watch. I also think you should try to make an opposed piston engine (where the pistons meet in one cylinder) because they're really cool and crazy efficient.
But I suspect, that the gears (especially when home made) that are necessary to combine the two crancshafts of an opposed piston engine will "eat" any additional efficiency. 😲 But it would be good fun. And to push it to the top, why not building a "Deltic" air motor?
I am no mechanical enginner but the issue you where discussing with the crank angle reducing torque and therefore making the engine less efficient is often solved by offesting the crankshaft to one side meaning at top dead centre the piston has a tiny crank angle in this case when the pressurised air is injected.
id also love to see some more common engine designs to be replicated, like an inline 4 (or inline 5 because its cool) or a v6. would be super super cool to hear what it sounds like
Love this series! I wonder if an offset crank would make any difference. They do this in road cars to change the angle of the crank when in the power stroke. Might reduce friction in your system too.
@@PrograError An i2 engine would have the cylinders sit side-by-side in a row like in a typical 4-cyl engine in a hatchback or sedan. What Tom built here was a Flat-2 or "Boxer-style" 2-cyl, most Boxers are 6-cyl in cars like the Porsche 911 where the pistons meet on the down stroke like a boxer punching his fists together before a fight in the ring. Unlike a true Boxer engine, what Tom built has the pistons alternating places so when one piston is at Top Dead Centre, the other is at Bottom Dead Centre (thing like two men working a saw on a tree - one pushes away as the other pulls towards).
Not sure if you factored this, but in the high residual volume engine, the air expands to atmospheric pressure and will therefore not exit the exhaust ports after the initial flow between the ports opening and BDC. When the piston hits TDC, the cylinder will already be at almost the same pressure as the air supply so you won't get very much air flow in.
Have you thought about switching from a standard propeller and a toroidal propeller? Less cavitation and more efficiency might equal longer more steady flight? I'd be very interested in the results of such a test.
I am also very curious. Intuitively I would guess the toroidal propeller would do better in a low power, low weight situation like this. But then again I've never seen a horizontal toroidal in the air before, only vertical
I actually dont think it would be so. First of all you usually only puncture a small hole on such a canister, so even though it may very well be 800 PSI internally, the operating pressure of the engine would never effectively reach that unless completely stalled. Also as CO2 is released from such a capsule, it is cooled and the vapor pressure drops. There used to be RC engines that ran on CO2. Of course valve spring etc maybe have to be adjusted, but structurally I think it can handle it no problem depending on what polymer you print with etc.
@@ET_AYY_LMAO Well 800psi in a volume of 14cc, at 100psi it has a volume of 112cc. That's 112ml, Tom is using 2,000L bottles at 100psi. Even at 60psi it's 186ml of volume.
somethign about when an engine "just sounds right" is so captivating. you can feel and hear if your car is not okay. you can try to start it and immediately tell something is wrong. And you can hear from the last twin cylinders in this video that it is WORKING
11:42 curious if u made that 180* out of phase, so both piston goes up and down at the same time, canceling each other momentum and maybe made it vibrate less
Eugh - I love these air-engine videos so much but this one was GREAT. The noise of that two-cylinder was incredible, and the THRUST! Holy heck! I'm not a particularly emotive person, but I was babbling and whooping with excitement watching this, for some reason. Great video, amazing engines, well done this chap. Gold star. Made my week, if not my month.
Very clever design. The quality of your prints is very nice too. I'm building/designing and printing a 1/4scale 51 Chevy Pickup truck. You've inspired me to consider converting the inline 6 cylinder engine to run on air.
I worked as a mechanic on modern cars and one of the more interesting innovations that you can possibly apply with little effort is the offset crankshaft design used on engines like mazda's skyactive. Might be a simple way to squeak out a little more efficiency where it matters
That is simply amazing. The best engineering-related project on TH-cam. And I bet you can optimize this thing to double it's current efficiency again! There is so much that can still be improved, in a positive way.
With the level of engineering done on these engines, I would love to see you tackle something like a compressing tank, something maybe with a spring that will keep higher PSI for longer by pushing a piston into the tank as air is used.
Tom, transfer the exhaust gas from one cylinder to the other (you will need a larger 2nd cylinder though to make it worthwhile). Also, use a cam to open the inlet port, that way you can time it at TDC so the cylinder is not being filled with any compressed air until it is on it's downward stroke. * if you used an exhaust driven 2nd cylinder you will have to time this so it''s also on the downward stroke at point of exhaust expulsion. LAUNCHER IDEA, if you make a launch system, be it hand or grown baised, you can rig it so the prop runs from a second air supply until it leave the launch device, this way the 2lt reservoir is not being used until it's in-flight & the air being expelled from the external supply could add prepulshion at point of release.
I'm very excited to see this take flight! Have you thought of a single cylinder setup with air intakes to the top and bottom? You can use a gear and bearing setup where you have the rotating motion of the gears, using the same thing bikes have to allow for one direction of rotation you can have both up and down strokes power the prop. It would need to rotate a circular crank-ring which attaches to the prop of the airplane, since it would make it much easier to run those gears and the bearings needed. I think 2 would be all that's necessary. The bottom piston rod would allow air into the cylinder through a small hole in the rod itself. A hollow rod also allows for lighter weight and stronger, overall, design. Since you have a crank-ring you could have that move valves instead that rotate and help air enter more quickly and efficiently with less weight overall. The crank-ring will rotate then rotate small valve plates with holes in them, allowing for air to flow into the bottom cylinder. The top cylinder too, if you want, with no need for the small rod on it. The rotating valves just need to be close enough to have the air flow in quickly at just after top/bottom dead center. Middle dead center would end up being your air vent valve, although if you place the correct valve placements on the rotating valve plates then you can have that be the exhaust as well until intake is needed. You would need rods that have gears on them to rotate the valve opposite to the crank-ring. Or just gears in-between.
I use such bottle as an air container for inflating tubeless mtb tires. I put around 8 bar in them regularly, and in mtb forums there is and opinion that 10 bar is safe, and they could handle 12 bar easily. Knowing that i still use eye protection and put a blanket or rag on them to reduce the shrapnell just in case. Got an mtb tire blown of the rim by high capacity 8 bar industrial compressor ( the pressure gauge was broken hence tire explosion) . That was a life changing experience, and taught me to respect anything presurized ( the ringin in my ears lasted two days).
I had an episode of airgun shooting, it seems that a lot of concepts are similar to your air powered engines, like smaller power output while operating on the highest pressure levels. Anyway, love the series and your content for years already. Thanks for that!
You can use compression springs inside of other compression springs to provide a precise, desired pressure. When doing this, you can use a bushing of a variable length on one end of the inside spring to more precisely tune the overall spring pressure provided by the entire spring stack or column.
It sounds like a 2 stroke motor which is really awesome. Your design acts very similar to one as well with a reed valve for air intake and using ports on the side of the cylinder to exhaust.
...and then there's me, instantly thinking about whether or not a radial 5/7/9 cylinder air engine could be built based on your cylinder design, how amazing it would probably look and sound and if a simple power control could be implemented using just a small ball valve on a servo after the regulator or if ithe engine would stall just a bit below its normal working pressure... Superb videos, just waaaay too few of them for my taste :D Always a nice start into the day when I see there's a new one. This channel combines quite a few of my interests.. engineering, electronics, RC, aircraft of various designs, ... Keep up the good work!
you should use graphite lubricant so it can run smoother also don't use oil because for some reason 3d printed plastics absorb oil and once it touches oil it is going to be oily forever
At 6:04 your explanation of why the engine with no "expansion volume above the piston" is more efficient is incorrect. The left engine initially transfers 10CC of high pressure air into the "expansion volume" without producing any useful work on the piston which is at TDC whereas the engine on the right is using the entry of the high pressure air to push down on the piston transferring energy to the prop. In this phase it is operating in a constant pressure regime. Once the engine on the right has 10CC of air in the cylinder above the piston it is now in the same state as the left engine (volumetrically, not crank angle) but it has already done some work unlike the left engine. Both engines can now expand the air to atmospheric pressure doing exactly the same amount of work, albeit with different pressure/time profiles due to the difference in crank angle. Obviously the right engine would need a longer stroke to achieve the same 3:1 expansion given that it started its (adiabatic) expansion phase later in the stroke. The torque/time profile will also differ but ultimately the energy out per stroke is force x distance regardless of how its metered out over time. The lost energy in the left engine is a result of friction losses as the air travels at high speed past the valve from the 60psi reservoir into the 15psi, 10CC "expansion volume" above the piston.
Thank you for making interesting stress free content. Perfect for jump starting my brain this morning. I appreciate the effort you put into making videos for us.
After watching all the videos Bro just made me realize that I wasn't wasting time in school learning physics. Way too impressive, creative and inspiring. I hope your channel grows quickly.
Gobsmacked! Thank you Tom Stanton for a quarter hour of quality edutainment. Engineering, R&D and persistence shown on video brilliantly. (*thanks also to Incogni for helping out)
Your videos are part of the greater TH-cam science content, and it's making math, science, and engineering more interesting to the masses. Keep it up, man.
Here's a project idea: add a schrader valve to a bike frame's down tube so the entire down tube can be an air tank. Fill it at home and it can refill your tyres several times without a pump. It only adds the weight of the air it holds and the hose, so it's probably lighter than a mini pump too. Unlike a mini pump, this would also be capable of getting the bead back on a tubeless tyre.
![ร้อยพ่อพันแม่ - WanMai [Official MV]](http://i.ytimg.com/vi/XY2pNYASEbg/mqdefault.jpg)
The first 100 people to use code STANTON will get 60% off of Incogni: incogni.com/stanton
Have a look at the engine Richard Pearse used in his aircraft
Question: What about either multiple air tanks or a multi-chambered tank with a system to switch from one chamber to the next as a way to keep a more consistent pressure throughout the run. Either a pressure regulated selector or a timed clockwork style of system to achieve the same result. Higher initial pressure would be required to see any real gain though. I think.
th-cam.com/video/fE_LjQ4IBQQ/w-d-xo.htmlsi=JYrUbne4WU5eEHE3
integza built one with magnets intead of a ball valve
What about using an *_offset cylinder_* to compare power & efficiency vs a "standard" configuration?
The sound of that twin cylinder was mighty impressive Tom
That was pleasant sound indeed
10:1 is a extremely good engine. That's why it sounds so good.
he should make a v12 version and build a wwii fighter with it
Sounds like a diesel under load
Like a revving motorcycle.
Tom's air engine project has been hands down my favourite home-made science video series to follow on TH-cam for years. This thing started as a curious fun project and is slowly turning into a slick usable design
This! :)
Couldn’t agree more. I can’t begin to describe my excitement of seeing this video in my feed 😂
For sure. I have loved this entire series. Can't wait until we can see these improvements on a plane or whatever he decides to put them in.
Agree
Yeah! I love the determination to see it through to become a viable motor
I love the twin cylinder that you built. I want to see you build a 6-cylinder radial engine just for the heck of it. Would sound amazing!
Or a 12cil? 2 inline 6cyl 😂
I work in bottle engineering, and part of the test we perform on the samples we make is a burst test. A 300ml bottle for highly carbonated products if well blown, can easily reach up to 15bars before bursting (not that i would reccomend reaching that pressure, as we do it with a proper machine that uses water instead of air). A 1500/2000ml falls a bit short of 12bars.
Anyway.
Beware that by making the hole on the bottom of the bottle, you are definitely weakening the overall resistance of the base, i would try to pressurize the bottle by adding another valve to the cap instead.
Keep up experimenting!
Just for the record in the water rocket community its well known that 120 psi is generally where these 2 liter bottles tend to explode. 100 psi is about the upper safe limit you would want to pressurize, 60 psi is almost entirely safe and 80psi is about the upper end of that. Though these are rough figures they should apply about the same.
It's also worth noting, its generally not dangerous, just loud, its a little bit of thin plastic, the most it'll manage to do is scare you pretty badly. Unless it sends something flying somehow.
@@killingtimeitself You even try a SodaStream bottle? Not quite as light, but they can handle a LOT more pressure. I've had mine up to 175 psi(12 bar) with no issues... which sort of sucks because I was trying to pop it to scare somebody. I later watched a video from the good folks over at Beyond The Press who had one up around 25 bar(360 psi) before it burst with deformation appearing to occur somewhere near 20 bar(290 psi).
@@dw7444you could always wrap it in packing tape
@@dw7444 i've seen wrapped and reinforced 2l (carbon fiber and kevlar iirc) that can do upwards of a thousand PSI, if you really wanted to maximize thats probably the way, though im sure that increases weight by a minimum of tenfold.
For people that don't like mixed unit conversations:
15bar = 218psi
12bar = 174psi
8.3bar = 120psi
6.9bar = 100psi
5.5bar = 80psi
4.1bar = 60psi
And for people that haven't seen the metric light yet, 1bar = 1 atmosphere
I love seeing your creative approaches to optimizing something so small, the redesigns, and all the quasi-microscopic changes that go into yielding a slightly higher efficiency each revision. This is probably one of my favorite series!
Contrats on the video, the quality of your content is insane. As a mechanical engineering student, I realize the amount of hours you put into every single video is absolutely insane. Keep up the hard work! Well keep supporting!
Wow, the progression between all of your pneumatic engines is impressive. I love the simplicity of the mechanical feedback loops, they are so clever! Great videos as always Tom.
The amount of work behind these projects is simply amazing. Well done!
It's only a matter of time before Tom creates an air powered V6
i was just thinking about traing to make a v6
This was so incredibly cool. I love the graphs, the animations, the slow-mo, and the mechanical nature of your projects. I can't wait to see what comes next! This air piston series has been incredibly fun to watch so far.
I absolutely love this series. It is the definition of engineering. Literal years of R&D with many challenges and setbacks, the evolution of tools, equipment and materials used, all to improve design and efficiency. Keep up the great work Tom!
OH! I just read your bio and realized that you have a degree in aerospace engineering! I'm a highschool student and this series has really really interesting to me and actually kind of inspired me to look into and go after aerospace engineering once I graduate from high school and I didn't even realize that that's exactly the path that you took lol. Thank you for making this series, it's truly an inspiration to me and I would bet many many others as well.
Your animations are really helpful and high quality, I wish more DIY orientated engineering channels had them
High quality animations?
I farted
Yeah the whole thing was cgi, I'm glad it's still watchable. Tom def has a good team
@@HaloNeInTheDark27 yeah @ 1:11
@Bctran02 nice
5:45 you can make it so that TDC actually corresponds to high crank leverage angle by offsetting the cylinder from the crankshaft. Also do note that you can't really expand to atmospheric pressure because then exhaust would not occur. With a bottom discharge port design, the piston compresses the air on its way up, so higher expansion volume just means there's less intake resistance so bigger charge of air can enter. It makes it more powerful, not more efficient.
Offset crankshaft is a good idea👍
his seal design means there is little to no compression on the upwards stroke, though. exhaust at atmospheric pressure is done by the piston pushing the air down around it's sides and out as it moves upwards.
Agreed on cylinder bore offset - came here to suggest that very idea.
I came here to suggest the offset crankshaft too.
They used that trick in the 50s to cheat on car racing.
Isn't that called a desaxe engine?
The 10x performance increase is just incredible. Optimisations like that are game changing. I bet you get approached by model airplane manufacturers and stuff soon if not already
Now make a radial engine version of it with even more cylinders!
A Pratt & Whitney r-4360 wasp
Exactly what I was thinking
But he just told you that the double-cylinder engine is half as efficient as single-cylinder!
@@Rhannmah MOH POWAH BAYBEE
Air powered P47!
@@Rhannmah You can bring facts, science, math to ameritards... but never expect them to accept it.
We sure have come far in the compressed air engine technology!
Pumping up you car before going to work 😂😂
@@Guenther-Eichinger Lol!
We? Please explain to the world your contribution.
@@Guenther-Eichingerinterestingly, that's not as crazy as it sounds. There are actual prototypes for air-powered cars that get similar efficiency to electric vehicles, and would potentially be cheaper and easier to build (not to mention much more encouragement friendly than lithium batteries)... One day you might actually see pneumatic cars on the road 😁
@@ShainAndrews"we" as in the general sense.
I wonder if having the cylinders offset would be a better option than having the curved rods. Traditional aircraft engines as well as BMW motorcycle engines (which I think were actually for aircraft originally) are also built with offset cylinders. With this miniature 3D printed design it might not even make a difference that could be measurable but might make for a good test. With the bore and especially the stroke, the change in curved rods to going with straight rods may show a difference in the torque as well as reduce the friction on the piston walls with the rods parallel to the pistons and cylinder walls and also reduce any air loss due to the pistons riding slightly cockeyed in the cylinders due to the rods being connected to the crankshaft at a small offset distance. Great work, Tom! I really like the content that you present on your channel.
It’s great when you release a new video on your air engines, it’s been really wonderful seeing the progress you’ve made over the years on this… great work Tom!
Absolutely tickled by the extremely elegant pneumatic manifolding and mechanical design going on here! One of the best explanations online about how a regulator works too. Great work!
Maybe after the Kegrocket is ready you could make an air powered Kegdrone 😛
Man, oh man, the sound of that 2cyl engine at the end was plucking at my heart strings, it sounds fantastic! Makes me want to build a desktop version just play with the throttle!
Tom, never stop making videos! They're so much fun to watch and see you overcome challenges through analyzing little details that add to efficiency
Seeing the huge difference with the last flown design is just insane. Can't believe how far your designs have come
A simpler solution is to have 2 supply tanks, the later (and smaller) at a lower pressure to match the engine.
This allows the main tank to be connected via the constant pressure valve. The run tank needs to be large enough to absorb the oscillations.
The main tank can then be refilled on a long duty cycle of the supply compressor, starting just before the 2 tanks equalise and stopping at the max SWL of the main tank
This system, (called cushioning), is used in high temperature heating systems. It allows the water to be held at a constant high pressure without boiling. The second tank has to be large enough to contain the volume increase of the water due to expansion.
When the water is in a sealed loop, a primary tank is not always needed.
That air powered mini 1/2 VW is beautiful! Quite keeping to tradition of the home built aircraft and sounded stunning. When you pushed the air up and let it go, I was in awe. Keep it up!
it’s so weird yet amazing to have watched your videos for almost 6 years now and be able to watch as you spread your wings and share your creativity and intelligence with the world. you inspire an unimaginable amount of people with your videos and it’s absolutely beautiful to see your community grow! it’s you and a handful of other youtubers that are guiding the next generations into the world of engineering. thank you tom stanton for the amazing videos!
Tom, I am beyond impressed. I'm very proud of you and your resilience to the strange issues that came up, and am so glad that after each time you were seeking an answer or improvement and found it, every single time. You have to be one of my favorite TH-camrs and I love watching you and the things you create. Seriously, great job. Keep up the good work, and have fun designing the airplane for this badass engine!
Couldn't agree more - Great work Tom.
You totally hit this one out of the park Tom, been following you for years and this series is an instant watch. The sound of the boxer air engine was insane and ik sure you can manage increase the efficiency of the single piston more. Would love to know the theoretical limit of it to compare as well!
Tom, you could improve efficiency even more by keeping the head design with no upper expansion area like you have now; and simply increasing the stroke volume to the point in which the expansion ratio is sufficient to your liking & DOESN'T have that high pressure delta when it goes to exhaust from the ports. And also finding a way to ensure that there is no compression stroke, only expansion, like a Miller-cycle on steroids. Not to mention the extra crank leverage you would receive with the stroke increase, would allow a larger, slower prop, etc.
Please upvote this so Tom might see it, I am 100% sure I am correct about what I'm saying. Thanks.
I think the exhaust is the issue with the engine as you point out, there is a big compression stroke! if the expansion happens and the air in the cylinder is at 1atm at BDC then no air is going to leave the exhaust port, as the piston starts moving up there will be a tiny bit escape before the ports get covered but most of the air gets re-compressed and wastes most of the energy. the exhaust port should be in the piston and opened by the crank shaft, when the piston gets to the top it should close.
@@Hootie811 I think he is avoiding a compression stroke by having seals that don't work without pressure. When the valve opens and high pressure air flows in, the seal is pressed outwards against the cylinder walls. Then when the pressure is released, the seal springs back away from the wall, allowing the air to move past as the cylinder moves back up.
@@robertbackhaus8911 That's a neat design. Its funny how many actual engine concepts he manages to cover (by accident or not) just by developing these. I was wondering if he was going to try and implement some scavenging though I wouldn't see it being effective at all.
I was wondering whether higher engine rpm, from using a shorter stroke/bigger piston and a geared-down prop, would help efficiency. But I'm way over my head in the science!
@@robertbackhaus8911 I have also been thinking and testing of another way of doing this. You use a tilting piston that would seal just a slight bit before the valve opens, and the friction would also be *very* low, since the absolute only contact area that the piston has over the whole cylinder is just the seal, and that contact area is even less when it tilts. You would also reduce the amount of moving parts doing that aswell
Here is another point to increase your efficiency significantly: make the exhaust air leave the cylinder all the way up to the TDC.
The reason your version with larger air volume was less efficient is because at the point where the exhaust openings were actually working the air pressure dropped to about ambient pressure so only little air could escape. Thus most of the air got compressed again by the piston going up, eating up all the energy gained on the way down.
Of course this needs a timed valve (think combustion engine), which is a challenge on its own...😁
Perhaps a small extra checkvalve? So it opens as soon as there isn’t an excess in pressure
@@xmysef4920 There needs to be an excess in pressure, though. Otherwise the air won't get pushed out.
I think the valve needs to controlled by the position of the piston: it needs to open when the piston is at the lowest position up until the piston reaches the highest point.
Maybe a spring loaded valve in the piston head? Valve is open up to ~1.5bar, but closes at higher pressures. Might be hard to do at such small scales.
@@toolscientist cam shaft, my dude. Making it save more energy than it steals is the trick.
The engine already does this, you need to check his earlier videos. The rubber o-ring on the top of the piston deforms to seal the cylinder as the pressure increases on air inlet, and then returns to its original shape as the pressure decreases at the bottom of the stroke, so air can move around the piston as it moves up the cylinder, it isn't sealed during this part of the cycle. There is no compression on the upward stroke. Y'all are coming up with solutions to a problem that this design doesn't have.
This whole Pneumatic Engine series has been fantastic from start to finish and I feel like at this rate, you're going to come up with some inline 4 design that uses air-injection and electronic control to get the maximum possible efficiency!! I cannot wait to see where this goes, as this is super exciting work!!
What you see with the higher pressure and lower output is well known to pcp air rifle users as valve lock. There comes a point where the pressure in the tank is too high for the “hammer” or opening device to open the valve freely. From the looks of your graph, I think 85 psi may be the sweet spot
Right....much of the physics going on here are well known in the PCP community and surprisingly flat power curves can be achieved with a well tuned gun. It would also be beneficial for the air engine to use a two stage design much like the steam engines on ships where a 'Hi-pressure' cylinder then exhausts into a 'Lo-pressure' cylinder that's sized proportionally to efficiently use the lower input pressure. Steam has a much higher expansion ratio than compressed air so the benefits would be much less....still it seems wasteful to exhaust ANY pressure when the onboard supply is so limited. Entertaining experiments with the air engines Tom!
@@recoilrob324Or give it an exhaust manifold to get tome scavenging going, essentially create less than atmospheric pressure in the cylinder before the exhaust closes. Very much doable with flexible airhose on the twin cylinder. Might be interesting
I absolutely love this series. You're doing God's work. I bet you've single handedly inspired dozens of not hundreds of future mechanical and aerospace engineers.
Can confirm.
Too bad compressed air already fuels commercial airplanes, but you’re not supposed to know that
@@ghostwhite1648This is false. You're referencing a meme called the "jet fuel hoax" which purports that jet engines use fuel to start an air compressor which then somehow produces the required power to continue running without fuel. Another variation of this meme says that 90% of the input of the engine is compressed air while only 10% is fuel.
In fact this is a misinterpretation of the way that fuel/air mixture works. Combustion of kerosene in air is limited by the Oxygen content of Air, which is 20% O2 and 78% Nitrogen. By volume, only about 10% jet kerosene can be used before all the Oxygen is used up. The combustion heats the air which causes it to expand, which then drives the turbomachinery to compress more fresh air into the engine, this compressed air is then burned with fuel to repeat the cycle. So no, compressed air is not where the energy is coming from, it's where the energy from combustion is converted from chemical energy to heat energy and finally mechanical energy of expansion.
Now let me blow your mind!
This meme is ALSO a misrepresentation of the work of Viktor Schauberger, the Austrian scientist responsible for early experiments in vortex fluid dynamics. Viktor Schauberger discovered a mechanism to use hot, humid air and a cold sink, usually a cold water tank or body of water like a river, to rapidly compress ambient air to drive a turbine. This is using the opposite process of implosion rather than explosion used in combustion engines. Implosive engines still require a heat difference or humidity difference to operate because only systems that are not in thermodynamic equilibrium can perform mechanical work. The "repulsine" was Viktor's name for this type of cold implosion engine, and he was conscripted by Nazi Germany to construct prototypes for the Nazi war machine. It's unknown how successful this project was, but the principle behind the design is sound, as long as there is a cold reservoir sink available to dump the exhausted, condensed air. Without that temperature difference there is no source of energy to perform the mechanical work of compressing the air.
@@taylorwestmore4664 TLDR a YTer made a compressed air engine. We know the military is 25-100 years ahead of what we are given.
@@taylorwestmore4664 UFOs aren't real still too right? And the water in flint didn't have lead?
I was showing one of my friends this channel in my engineering class, and the professor overheard and came over and said he was a fan of the channel too. So congratulations on making content so good that teachers of the subject watch it for fun
What an honor to be following the development of this. Really impressive Tom
Man, i love this series.
Could you try to push the engines (even the old ones) to the breaking point?
Does it give insight into the engines? No.
Would it be cool? Yes.
It would allow to find the breaking point of the engines, and possibly make them more reliable and durable at those higher pressures.
@@BasedMan There's a lot to be learned when something fails. Something about, fail in every way possible in each iteration to improve the fastest.
I mean, it would definitely help define the upper boundary of the working pressure
The sound of that twin cylinder was mighty impressive Tom. The amount of work behind these projects is simply amazing. Well done!.
I just got a 3d printer and have been printing for the last month party due to your videos. It's so much fun. I've even started designing my own models as well. Thanks Tom.
You could consider prototyping a version with an offset crankshaft. Like you showed at 6:28, you'd get a more favourable crank angle to make better use of the high pressure air. This would approximate an Atkinson-like cycle, except unlike a combustion engine compression losses aren't a thing.
Yes I thought of this exact thing too. He should definitely try that
It’s been really fun to watch the progression of the engines. Keep up the good work, and the content coming.
Have loved this series from the start… kinda hope you never stop improving this. Fantastic effort and engineering!
A 10:1 thrust-to-weight ratio is pretty incredible. It would be cool to have remote controlled throttle on this as well!
You should think about changing this 180 ° V engine design to a 2-cylinder boxer to reduce the insane vibration that this thing has.
Your inlet valve operation working with a pin on the piston head is absolutely brilliant.
my man out here reinventing the diesel engine
Huh?
Not really, although CNC Milling a DIY One would be AMAZING
*open source mini diesel when*
You do such a good work that it looks easy. I cant imagine the amount of time you have put into this amazing high quality content.
I think you scrapped the larger expansion version a little too early. I'd come back to it and play around with cylinder offset, so the connecting rod is already past TDC when the air impulse comes in. I sure would like to see the results of that!
See: triple expansion steam engine. All ya gotta do is get the piston diameters matched to the previous stages exit air pressure & the efficiency goes way up.
This is such a cool project Tom! I had an Free flight air hog plane as a kid that had a pneumatic motor. Always thought it would be cool if you could make it R/C. Keep up the great work!
I love this series! Makes me want to try making my own 3d printed air engines.
Oh god now you have to make a radial air engine. I bet it will sound heavenly. Astounding work as always Tom!
I wonder is a Radial engine more efficient than a conventional V Engine (If not wrong, Radial engine pretty much not used anymore after WW1, with the usage only being for legacy designs)
Your teaching abilities are amazing. It is so cool how you manage to take me along with your way of thinking!
love the series, always gets me motivated to also try some air engine designs. For me with boxer engines having the connectingrods offset induced a lot of friction because of them wanting to spread and jamm. So offsetting the cylinders instead helped a lot although I always used a plastic crank and not even a circular one which probably amplifies the problem.
Awesome seeing an air engine again from you! Your videos on them are very interesting and are relaxing to watch. I also think you should try to make an opposed piston engine (where the pistons meet in one cylinder) because they're really cool and crazy efficient.
But I suspect, that the gears (especially when home made) that are necessary to combine the two crancshafts of an opposed piston engine will "eat" any additional efficiency. 😲
But it would be good fun. And to push it to the top, why not building a "Deltic" air motor?
YEAH!@@g.j.647
I am no mechanical enginner but the issue you where discussing with the crank angle reducing torque and therefore making the engine less efficient is often solved by offesting the crankshaft to one side meaning at top dead centre the piston has a tiny crank angle in this case when the pressurised air is injected.
I think a v8 engine would be very cool to see, you could also experiment with flatplane and crossplane crankshaft designs!
id also love to see some more common engine designs to be replicated, like an inline 4 (or inline 5 because its cool) or a v6. would be super super cool to hear what it sounds like
@@luukvanoijen7082 inline 5 would be awesome
Love this series! I wonder if an offset crank would make any difference. They do this in road cars to change the angle of the crank when in the power stroke. Might reduce friction in your system too.
I wonder if that might have been the "failure point" for the I-2 Engine (not sure what that config is called, so I based it on the V type engine)
@@PrograError An i2 engine would have the cylinders sit side-by-side in a row like in a typical 4-cyl engine in a hatchback or sedan.
What Tom built here was a Flat-2 or "Boxer-style" 2-cyl, most Boxers are 6-cyl in cars like the Porsche 911 where the pistons meet on the down stroke like a boxer punching his fists together before a fight in the ring.
Unlike a true Boxer engine, what Tom built has the pistons alternating places so when one piston is at Top Dead Centre, the other is at Bottom Dead Centre (thing like two men working a saw on a tree - one pushes away as the other pulls towards).
An offset crank might help indeed, would love to see a camshaft as well with inlet and outlet but probably too hard on miniature scale in plastic.
Not sure if you factored this, but in the high residual volume engine, the air expands to atmospheric pressure and will therefore not exit the exhaust ports after the initial flow between the ports opening and BDC. When the piston hits TDC, the cylinder will already be at almost the same pressure as the air supply so you won't get very much air flow in.
Fascinating Tom! Always worth the wait, your videos. Looking forward to seeing it on an aircraft - fuel much cheaper than the wallet-emptiers I fly! 😀
How did you reply 1h ago when the video was posted a minutes ago
Thats a damn good question
@@Keberal_kanobro broke the fucking matrix, proof that we live in a simulation
@@Keberal_kano Patreons probably get early access to an unlisted video
@@Keberal_kano He probably had early access through Patreon
Have you thought about switching from a standard propeller and a toroidal propeller? Less cavitation and more efficiency might equal longer more steady flight? I'd be very interested in the results of such a test.
I am also very curious. Intuitively I would guess the toroidal propeller would do better in a low power, low weight situation like this. But then again I've never seen a horizontal toroidal in the air before, only vertical
That amazing sound in the two-cylinder version...
Please please please make a two cylinder engine at 45 degree offset instead of 180. I would love to hear a harley air hog engine
Woah pls make a v8 next or radial maybe?
Oh man a radial would be awesome!
Bert Ponds famous Hoosier Whirlwind was a 3 cylinder radial using a crankshaft rotary valve.
Babe wake up Tom Stanton posted
Hi Tom! I was wondering if you could run these engines of a 12g CO cartridge?
Well, a CO2 cartridge is about 800-900 psi. Considering Tom is running 100 psi, that's quite a jump.
I actually dont think it would be so. First of all you usually only puncture a small hole on such a canister, so even though it may very well be 800 PSI internally, the operating pressure of the engine would never effectively reach that unless completely stalled.
Also as CO2 is released from such a capsule, it is cooled and the vapor pressure drops. There used to be RC engines that ran on CO2. Of course valve spring etc maybe have to be adjusted, but structurally I think it can handle it no problem depending on what polymer you print with etc.
@@ET_AYY_LMAO Well 800psi in a volume of 14cc, at 100psi it has a volume of 112cc. That's 112ml, Tom is using 2,000L bottles at 100psi.
Even at 60psi it's 186ml of volume.
somethign about when an engine "just sounds right" is so captivating. you can feel and hear if your car is not okay. you can try to start it and immediately tell something is wrong. And you can hear from the last twin cylinders in this video that it is WORKING
11:42 curious if u made that 180* out of phase, so both piston goes up and down at the same time, canceling each other momentum and maybe made it vibrate less
Great series! Keep going for that topic i love it!
Eugh - I love these air-engine videos so much but this one was GREAT. The noise of that two-cylinder was incredible, and the THRUST! Holy heck! I'm not a particularly emotive person, but I was babbling and whooping with excitement watching this, for some reason. Great video, amazing engines, well done this chap. Gold star. Made my week, if not my month.
So it runs of a gas... 0:15
I know what he meant is just a joke before anyone takes it too seriously
Been a year to your comment, guess no body took you serious 🥲
Here to make him famous
0:42 just fit a compressor on it duh 🙄
🐻🍍
Real
Then how would you run the compressor? Genius
you use tanks which are plastic soda bottles, aluminum , and in the old days brass.
Very clever design. The quality of your prints is very nice too. I'm building/designing and printing a 1/4scale 51 Chevy Pickup truck. You've inspired me to consider converting the inline 6 cylinder engine to run on air.
I worked as a mechanic on modern cars and one of the more interesting innovations that you can possibly apply with little effort is the offset crankshaft design used on engines like mazda's skyactive. Might be a simple way to squeak out a little more efficiency where it matters
That is simply amazing. The best engineering-related project on TH-cam. And I bet you can optimize this thing to double it's current efficiency again! There is so much that can still be improved, in a positive way.
With the level of engineering done on these engines, I would love to see you tackle something like a compressing tank, something maybe with a spring that will keep higher PSI for longer by pushing a piston into the tank as air is used.
I’ve been following the evolution of this for a while. This is impressive progress!
Hey Tom, I find this to be your most impressive project yet great work
Tom, transfer the exhaust gas from one cylinder to the other (you will need a larger 2nd cylinder though to make it worthwhile).
Also, use a cam to open the inlet port, that way you can time it at TDC so the cylinder is not being filled with any compressed air until it is on it's downward stroke.
* if you used an exhaust driven 2nd cylinder you will have to time this so it''s also on the downward stroke at point of exhaust expulsion.
LAUNCHER IDEA, if you make a launch system, be it hand or grown baised, you can rig it so the prop runs from a second air supply until it leave the launch device, this way the 2lt reservoir is not being used until it's in-flight & the air being expelled from the external supply could add prepulshion at point of release.
Now make a radial engine version of it with even more cylinders!. The amount of work behind these projects is simply amazing. Well done!.
I'm very excited to see this take flight! Have you thought of a single cylinder setup with air intakes to the top and bottom? You can use a gear and bearing setup where you have the rotating motion of the gears, using the same thing bikes have to allow for one direction of rotation you can have both up and down strokes power the prop. It would need to rotate a circular crank-ring which attaches to the prop of the airplane, since it would make it much easier to run those gears and the bearings needed. I think 2 would be all that's necessary. The bottom piston rod would allow air into the cylinder through a small hole in the rod itself. A hollow rod also allows for lighter weight and stronger, overall, design. Since you have a crank-ring you could have that move valves instead that rotate and help air enter more quickly and efficiently with less weight overall.
The crank-ring will rotate then rotate small valve plates with holes in them, allowing for air to flow into the bottom cylinder. The top cylinder too, if you want, with no need for the small rod on it. The rotating valves just need to be close enough to have the air flow in quickly at just after top/bottom dead center. Middle dead center would end up being your air vent valve, although if you place the correct valve placements on the rotating valve plates then you can have that be the exhaust as well until intake is needed. You would need rods that have gears on them to rotate the valve opposite to the crank-ring. Or just gears in-between.
You're a talented engineer and have such skill in explaining things from principle.
one of the best series on youtube. so cool to see different iterations of this design, and how it improves!
This is a triumph of rc aviation and 3d printing, seriously impressed!
I use such bottle as an air container for inflating tubeless mtb tires. I put around 8 bar in them regularly, and in mtb forums there is and opinion that 10 bar is safe, and they could handle 12 bar easily. Knowing that i still use eye protection and put a blanket or rag on them to reduce the shrapnell just in case. Got an mtb tire blown of the rim by high capacity 8 bar industrial compressor ( the pressure gauge was broken hence tire explosion) . That was a life changing experience, and taught me to respect anything presurized ( the ringin in my ears lasted two days).
Amazing video. Thank you for showing complex engineering, thermodynamics and manufacturing ... Visual!
I had an episode of airgun shooting, it seems that a lot of concepts are similar to your air powered engines, like smaller power output while operating on the highest pressure levels.
Anyway, love the series and your content for years already. Thanks for that!
I enjoy watching the progression of this long-going project so much! Thanks for another great video.
I love how I'm watching this at 01:33 in the morning
You can use compression springs inside of other compression springs to provide a precise, desired pressure. When doing this, you can use a bushing of a variable length on one end of the inside spring to more precisely tune the overall spring pressure provided by the entire spring stack or column.
An "air powered" revolution is just around the corner. This man just needs increased support.
It sounds like a 2 stroke motor which is really awesome. Your design acts very similar to one as well with a reed valve for air intake and using ports on the side of the cylinder to exhaust.
...and then there's me, instantly thinking about whether or not a radial 5/7/9 cylinder air engine could be built based on your cylinder design, how amazing it would probably look and sound and if a simple power control could be implemented using just a small ball valve on a servo after the regulator or if ithe engine would stall just a bit below its normal working pressure... Superb videos, just waaaay too few of them for my taste :D Always a nice start into the day when I see there's a new one. This channel combines quite a few of my interests.. engineering, electronics, RC, aircraft of various designs, ... Keep up the good work!
you should use graphite lubricant so it can run smoother also don't use oil because for some reason 3d printed plastics absorb oil and once it touches oil it is going to be oily forever
At 6:04 your explanation of why the engine with no "expansion volume above the piston" is more efficient is incorrect. The left engine initially transfers 10CC of high pressure air into the "expansion volume" without producing any useful work on the piston which is at TDC whereas the engine on the right is using the entry of the high pressure air to push down on the piston transferring energy to the prop. In this phase it is operating in a constant pressure regime. Once the engine on the right has 10CC of air in the cylinder above the piston it is now in the same state as the left engine (volumetrically, not crank angle) but it has already done some work unlike the left engine. Both engines can now expand the air to atmospheric pressure doing exactly the same amount of work, albeit with different pressure/time profiles due to the difference in crank angle. Obviously the right engine would need a longer stroke to achieve the same 3:1 expansion given that it started its (adiabatic) expansion phase later in the stroke.
The torque/time profile will also differ but ultimately the energy out per stroke is force x distance regardless of how its metered out over time. The lost energy in the left engine is a result of friction losses as the air travels at high speed past the valve from the 60psi reservoir into the 15psi, 10CC "expansion volume" above the piston.
Thank you for making interesting stress free content. Perfect for jump starting my brain this morning. I appreciate the effort you put into making videos for us.
After watching all the videos Bro just made me realize that I wasn't wasting time in school learning physics. Way too impressive, creative and inspiring. I hope your channel grows quickly.
Gobsmacked! Thank you Tom Stanton for a quarter hour of quality edutainment. Engineering, R&D and persistence shown on video brilliantly.
(*thanks also to Incogni for helping out)
Your videos are part of the greater TH-cam science content, and it's making math, science, and engineering more interesting to the masses. Keep it up, man.
Here's a project idea: add a schrader valve to a bike frame's down tube so the entire down tube can be an air tank. Fill it at home and it can refill your tyres several times without a pump. It only adds the weight of the air it holds and the hose, so it's probably lighter than a mini pump too. Unlike a mini pump, this would also be capable of getting the bead back on a tubeless tyre.
I can’t help it, I just gotta hear this as a V8 or Straight6. I need it