i suppose i should give a brief explanation of what i'd like to do and, though i'll keep my list short, truth be told i likely have more questions than anyone would want to read in one sitting.
basically i plan on designing an air propelled bicycle. i am looking at using a gast air motor and thinking of using two tanks of a as of yet undetermined size. i want to keep this relatively basic partly for aesthetics and because this is my first crack at air power. i've not decided whether i'll use a bike gearset. i've not set range or top speed goals yet and this leads me to my first question.
1) realizing many variables play a part i wonder if i can hope for more than a few miles range and a top speed approaching twenty miles per hour 2) what different types of regulator are being used 3) are there threads in this forum, books for the non-engineer, any other sources for the fundamentals- again, for the non-big brains.
in case i hadn't made it clear i'm not an engineer and big math equations make me car sick. i have had decades of experience repairing and tinkering with automobiles and motorcycles however so i hope i'm not utterly over my head.
i'd be more than happy to answer any questions and take any general advice on this project.
Post by Uncle Buddy on May 9, 2016 19:16:08 GMT -8
Few miles range is tops, especially with Gast air motors. There are ways of getting unlimited range but that's what the rest of this forum is about and I don't personally know who has proved it yet.
Nothing wrong with Gast but it's a non-expansive motor using more or less the displacement of the air and dumping it mostly unexpanded into the atmosphere, pressure unused or partially unused. The advantage of commercial air motors is that they have huge torque for their size and weight. But they use 30 cubic feet per minute free air equivalent per horsepower put out, or even more. I assume you're talking about piston air motors, which is the only way to go. Piston air motors give maximum torque at zero-plus speed, so they are perfect for air cars. Also good for climbing if not undersized for the load, because the car slows down and the torque increases. Like the old steam car book said, an expansion engine with 20 hp will surpass a combustion engine with 80 hp because of the better torque characteristics, especially notable on starting and climbing.
However, it's so easy to make an air engine from off-the-shelf actuators, valves, etc. But the only air car I made (big enough to sit in) used an old piston air motor and the starting power was amazing. Just a go-kart made from a riding lawn mower chassis. Other things to consider, I was once able to buy an old golf cart chassis very cheap, but never got around to doing anything and now I'm gone, I'm a ghost to this project. Something with four wheels gives you a lot more flexibility in my opinion.
Regulator. You'll be filling up at a scuba shop or something with high pressure air, for range, and regulating it down to working pressure. With really efficient engine you'd get 30 to 50 miles per fillup carrying the maximum practical number of tanks. With non-expansive air motor you'll get maybe 10 miles or less, just a guess. When I bought air in rented cylinders from welding shops they said I had to buy my regulator from them or they wouldn't do business with me, this was for their own protection in case I was going to try and put 3000 psi through an old junk regulator. I know nothing of regulators, mine was new and worked perfectly. We know they waste all that pressure but if allowed to warm up again to ambient temperature in an intermediate drive tank at working pressure, a lot of the energy will be replaced by the environment.
Books--see my website aircaraccess.com. All but one of the books is free now and recently I also gave them to archive.org which will be their permanent home because this earth is not my permanent home.
Hi Ecosse, If you want to stick with a bike I would suggest you look closely at Cory`s, and take onboard what Unc`s just written. Ambient heating and expansive working are very important. Even 50% cutoff of air will almost double range.
Hey Uncle and Chris thanks for your input. Let me first say that just about 30 minutes ago I downloaded several of Uncle's books and look forward to my new reading assignments. I stumbled upon Gast and was attracted to them because, as a novice, it seem well engineered and built and a bit of an idiot-proof intro to powering a vehicle with compressed air. Their torque claims seemed attractive and given the motor's light weight and compact size, compared to the ICE and steam engines, seemed like a good choice for a bike. I will now seriously look into building a piston motor following Uncle's suggestion.
Currently I am settled on a bicycle for a few reasons but understand it poses packaging issues. Every design solution causes another problem doesn't it? I am considering the use of bike gearsets if they can withstand the power hoping this could help range and top speed.
The matter of what regulator to use, what type of valve to use, where to source tanks and what kind, and where to fill up are all showing up on my radar now.
Clearly I need to learn about the importance of heat and what relevance motor designs and size have. Again, I'm trying to keep my ambitions within reach of my resources, knowledge, and goals but I also want above all else to have a well engineered and moderately practical effort.
These are vane motors. Notice it took a lot of looking on the catalog page to figure this out. This is typical of modern pneumatics for industry, the minimum of useful information is given, in case someone out there is trying to learn something. We are not supposed to be learning how compressed air works, we are supposed to be buying stuff.
Look for piston motors but if you study the materials of Terry Miller, you'll see how easy it is to build your own air engine from pistons (actuating cylinders) that can be bought from industrial suppliers.
I got a "piston air motor" from a surplus mail order catalog once and it didn't seem to do anything. Finally figured out that it was a vane motor. Vane motors do not have the torque characteristics of piston motors, they need rpm. Piston motor has its greatest torque when starting from absolute zero rpm. So your car comes to a hill and tries to slow down, but when it slows down, the torque goes up... get it? Piston air motors are absolutely perfect for wheeled vehicles. Leroy Rogers' converted gas engine would pick up the front wheels when starting up the car. Bill Truitt had to put a limiter on his, it was so powerful it was scary to drive. I built a go-kart with an old riding lawn mower chassis and it started so fast I could barely steer it... this is headed up a steep hill.
I have just posted three videos on homemade air engines on archive.org along with all my other stuff from the site. One of the videos is from Terry Miller, one is my torquerack engine--super simple and no crankshaft--and the other is my compressor to air engine conversion. I should have uploaded these videos a long time ago, but my modem just recently got good enough to do it.
At archive.org, search "pneumatic options". The videos and most of the other stuff is listed on the results page.
Look for piston motors but if you study the materials of Terry Miller, you'll see how easy it is to build your own air engine from pistons (actuating cylinders) that can be bought from industrial suppliers. I have just posted three videos on homemade air engines on archive.org along with all my other stuff from the site. One of the videos is from Terry Miller, one is my torquerack engine--super simple and no crankshaft--and the other is my compressor to air engine conversion. I should have uploaded these videos a long time ago, but my modem just recently got good enough to do it. At archive.org, search "pneumatic options". The videos and most of the other stuff is listed on the results page.
This Terry Miller video is a MUST SEE! Do yourself a favor and take the time to download it to your own flashdrive for future reference. Notice he continues to repeat that the energy source is the kinetic energy of air, I cannot over-emphasize that is exactly what is his energy source.
I believe this video is about 25 years old. What has happened to the development since that date? Nothing in the public eye.
Unc, is it possible to create a link directly to this video in archive.org? Is so, why not spread that link near and far, I mean there are several energy forums on the internet and mechanical forums also. I say, shotgun the link far and wide. Send me a link, I know of some academic locations where some young engineers might find this very interesting to view.
Terry Miller is a true prophet and a very accomplished builder, notice he does not brag because he is totally confident in his abilities which are proven in this video. His knowledge is thorough, which gives him the ability to explain in simple terms.
Like most prophets, the harvesting of his labor fruit will occur after he has passed on from this earth. If anything else, viewing this video will get your motivator in gear to get to work! Seeing him motoring in the fast lane got my blood pumping! At the end, watch the motor in action.
Unc has a pdf photocopy of the complete specs and dimensions for the earlier version aircar#1.
Do yourself a favor and spend 30 minutes in the Terry Miller air car classroom. I tip my hat to his know-how and genious!
Post by Uncle Buddy on May 13, 2016 19:37:49 GMT -8
Terry was one of my early inspirations and I was lucky enough to meet him. I even got to drive Air Car One in circles at the 1985 Wichita Energy Exposition for two days.
After showing Air Car One, the patent vehicle, from coast-to-coast, Terry was pretty much burned out and not making any money. But in the 1990s he formed a partnership with a jewelry shop owner in Joplin named Toby Butterfield and they put together the cars shown in the video. This attracted the technical press, not just local newspapers. The equipment including the big air station was all donated by the corporations who saw Terry's track record, and all they wanted in return was a decal on the side of the Spirit of Joplin air car. Terry wasn't afraid to ask for things. As you say, he was knowledgeable, a lifelong technician. He was a retired tech school instructor, an aircraft electrician.
But Terry had diabetes and was easily bored and not very interested in making money, he mostly wanted to teach. He and Toby's interests grew apart and Terry gave his share of the project to his daughter who wasn't very interested. Toby hired a local engineer who scrapped everything and started over by converting a Honda 500cc V-twin motorcycle engine to run on air. When this project also fell dormant, he sold this engine to the University of Washington who used it for a cryogenic car that ran on liquid nitrogen. When this project was long dormant, I bought this engine and took pictures of it. My book Air Engines also has an interview with the engineer and his drawings of the rotary valve he made for it.
But the most important thing I want to repeat is that Terry taught us how simple and easy it is to run a piston engine on compressed air, anyone can build one. My torquerack engine was all made by hand, and my two-stage engine needed only one bit of machining done. Terry taught to keep the speed low and then high tolerances and lots of machining aren't necessary.
The other thing I learned, at the Energy Expo in Wichita, is that people love air cars. There is something intrinsically exciting and interesting about running a car on air, while people kinda know intuitively that electricity is scary and not to be trusted. I mean, where are we gonna put the dead batteries, much less find the lithium for new ones?
Thanks Uncle and tommy both for your input. I'm now taking seriously the prospect of building my own motor based on the advice here but also am considering converting a small steam engine. There are designs by Ray HasBrouck that had piqued my interest when I was more seriously considering steam and wonder if I might be able to use one for air (this one in particular hasbrouck.8m.com/eng4.htm ).
My impression is that the air motor type you guys are recommending may be lighter weight overall (and more efficient?) but a feature of the steam engine adapted to air I perceive is that the power is converted to rotational motion within the unit possibly requiring less machinery, gears, etc thus being more compact. I tried to download the ebook "Air Powered Cars by Terry Miller" but it seems to be unavailable. I did begin to watch the video Uncle linked to but will have to wait until I have a bit more time to watch uninterrupted. Some of the ebooks I've downloaded so far are a bit over my head but admire Uncle for collecting this treasure of info and generously sharing it.
I have to agree with Uncle's assessment of air power's attraction. Similarly to steam (although that frightens some as well), and aside from the rational interest in air power's potential, the right balance of the elegance of good design and the dance of mechanical bits in motion can be mesmerizing. I also think one of the several reasons many are drawn to turn of the century machines is the reminder of the inventiveness possible when a builder/inventor is free of industry standardization and choking regulations; this "underground" movement of air power I think shares that spirit. Call it nostalgia for freedom.
I wouldn't mind studying Terry Miller's early design as well. Really, thanks guys!
Post by Uncle Buddy on May 17, 2016 19:41:37 GMT -8
Thanks for reminding me about the bad link. I'm getting ready to stop hosting the pdf's so won't fix it, but the pdf's are already available at archive.org. Here is a good link for Terry Miller's book:
You are correct that the crankshaft engine is more compact than the rack-and-pinion crankless engine. Probably more balanced too. The rack-and-pinion has constant full torque vs the crankshaft whose torque varies throughout the stroke.
As for steam engine conversions, the steam and air engine work pretty much the same, they are both expansion engines. Air engines have no condenser obviously. Seals might want to be changed from high temperature materials to low temperature materials. The other thing to watch out for is what controls the steam going to the cylinder. I joined a steam engine modeling club once, thinking the members would understand valve gear, but they weren't into those kinds of details. If you expect a really efficient, convenient engine, you need one with reversing gear. That means adjustable cutoff, even to the point where the whole engine is reversible. This also eliminates the need for a reverse gear on your transmission.
Without adjustable cutoff, either it's too powerful and using too much air during cruising, or it's too weak to start the car or climb hills.
after my last post i watched all of the video mentioned above and spent some time reviewing the various postings at archive.org including the one on mr. miller's car. i'm not sure if the steam engine i linked to has a reversing gear although i know some of the other designs incorporate it. been trying to get some info on the hasbrouck yahoo group about that #4 engine (thinking it might be the right size for a bicycle) but no responses yet. can i just say i absolutely hate yahoo group's interface? horrible navigating it.
i'd consider converting a gasoline engine as well if i can find one small enough and that isn't made in china. also, uncle i watched your video demonstrating the torquerack engine and have to say it's a pretty impressive concept. have you developed it further or built others?
could i trouble someone for some leads (manufacturers, distributors, etc) on actuators, valves, and related bits? i don't mind doing my own research but i'm not very confident in my knowledge of what to look for. any tips are greatly appreciated.
i'm sorry for the barrage of questions. perhaps i'll just dive into the info i have now and come back later.
Post by Uncle Buddy on May 20, 2016 23:19:49 GMT -8
There are companies like Graingers where you walk in and start asking questions and they will help you. Machine parts for sale, they want your business. Otherwise there is always Thomas Register which classifies manufacturers by what they make. I don't know if they still have these in the public library, no doubt they have a website but I don't know if it's free.
Armando Regusci has developed the torquerack idea by using chains and sprockets instead of gears. He's the most active of air car inventors that I know of. The next Terry Miller. He lives in Uruguay.
Hi Ecosse. I hope you are making progress wading through all the info.This may muddy the waters a bit! The 4 engine does not have a reverse,and for a bike you don`t need one.I see that many people convert small 2 stroke,ex strimmer, engines to both steam and air power.I would think on air with airline oil in very small doses they would be fine.You could use a valve similar to HasBrouck`s 4 engine;arranging inlet cutoff for 30% stroke. Bear in mind it will automatically start exhausting at about 80% stroke.For a first conversion attempt an eccentric with piston valve will be simplest,as I think in the 4 engine.I know the compression and large clearance volume go against this type of conversion,but the engine should be free;and the fins will take in ambient heat;although it will lose heat of compression. Very cheap,minimal work.
I see the Hasbrouck 4 engine is only 5/8" bore 1/2" stroke.You won`t get enough power out of it. Nice simple design though.I have the book of his engine designs;a clever guy, well worth taking note of.With a bit of thought you could enlarge the design and use aluminium wherever possible to stop overweight for a bike.