Air Powered Bike Range 

Ok next step: wood or coal fired steam boiler

7:10 sounds like an asthmatic Darth Vader doing the cycling.

the attitude with which you accept and overcome small failures is the reason for you huge successes. you really inspire me to not give up on things when I hit a snag. Thanks Tom, you really are an inspiring guy.

"Oh, that's a lot of power" - traveling at10 km/h :)))

Next up: Nuclear reactor powered bicycle

This project looks like a lot of fun. One idea: you should add more piston stages cascaded in series, so you can recover some of the energy in the exhaust venting.

It’s impressive how much time and effort you put into your content

If you were to revisit this project you may want to take into consideration that there is a difference between the volumes of the extention and retraction because the retraction has has slightly less volume due to the air cylinder shaft retracting into that area

That bike sounds disturbingly familiar with me challenging any serious incline... ;)

Now it is time to get even more impractical and make an electric-pneumatic hybrid bike by adding a battery powered air pump. You could then add a roof on it with solar panels to power the whole system. If you made a snappy enough video of it, you could make a killing on kickstarter.

Loving the diagrams and calculations Tom. Super fun to watch

Great video. So much can be learned from something you know is not the best idea, just even the knowledge gained from improving a bad idea can be applied somewhere else. Brilliant, keep making and pushing ideas.

Your projects are some of the best on RU-vid.

I want to see a v8 engine of the mini 3d printed compressed engines. That would be so satisfying to watch. This bike is a really cool concept, keep up the good work.

"Like with every vehicle, the more power you output, the less range you have." The SR-71 would like to have a word.

Thanks so much Tom, I very much enjoy your projects and videos.

Your air powered bike is begging to be displayed somewhere worthy. What an awesome project Tom. Cheers!

Sounds much better than the explosive popping from the last video... Anyhow, 400 meters seems like a good guess... :) nobody actually does these guessing things I think.

Very interesting! We take for granted lipo power density sometimes! Also can I say it looks like the new vids have been picking up a lot more views recently? That's awesome!

"If the exhaust pressure is at 2 atm, it effectively halves the range." This is why compund expansion engines exist, so as to utilize this exhaust pressure to further extract energy from the pressurized gas

How about CO2? Stored as a liquid good high pressure, plenty of gas relatively cheap

You should try a vane motor, they're used in most rotating air tools. Very efficient.

Hi Tom, you can find used carbon fiber SCBA tanks that the fire fighters get rid of. They fill to 4500 psi or 310 bar! You may be able to find one for very cheap at a pellet rifle store. They can usually fill them there too. Theres a chance that a dive shop may have them as well. And either will have used steel and aluminium tanks for even cheaper.

Wow! Thats was a good development even though its little. People like you makes this world goes to the moon. Keep it up man

Now to add a steamboiler and making it triple expansion.

I'm guessing 100 meters. Edit: Well, I'm impressed ;)

Thank you for your research! Fun to watch your build.

Fantastic test and build. Excellent build and video mate!

The sound this bike makes is exactly how i breathe after I run for 10 minutes.

It sounds like me riding when I am out of Salbutamol.

This is the content i subscribe for Other channels lack such a detailed Mechanics!

very interesting tom. Thank you for the calculationa dn very well produced video

You need to find a carbon fiber air tank that firefighters use. Our tanks can be pressured up to 4500 psi and they are lightweight.

The regulator is expanding air to a lower pressure without extracting any useful work in the process. Variable valve timing (with no regulator) would allow you to extract a much larger fraction of the energy.

Another issue you might face using a scuba tank is the regulator. A scuba diver uses about 15l of air per minute near the surface, or 5 times that at 40m depth. That requires the regulator to be submerged in order not to cool down too much to freeze shut. In air heat transfer from the environment is a lot lower and a regular scuba regulator might well freeze at the rate you're taking air out of the tank.

Haha that wide shot where the the sound is the same volume but you can see how little ground is covered for all that huffing and puffing. Funny, and totally awesome.

Maybe the key is to put the air tank on a trailer. That will fix the center of gravity problem and possibly allow for a larger, heavier tank.

Why don’t you add air compressor to the pedals, so when you pedal you’ll be slowly adding more pressure to the tank to extend the range? Or even connect it to the bike tyres?

This is very interesting, and I learned a lot about how pneumatic cylinders, etc worked. Especially interesting was the efficiency loss when the exhaust pressure was greater than the atmospheric pressure. Many Thanks! PS a steam powered variant would be great, I can imagine strapping the boiler on the back!!

you have given valuable datas to make a decision . thanks for your detailed R&D and explanation.

The input pressure regulation is wasting the excess energy, full pressure + variable intake timing would do better for economy

Love your stuff!! Keep it up. Curious what would happen if you drilled a Few more exhaust holes on the return stroke side of the cylinder.

His science explanation makes my head spin. Lots of effort into this thing with less than stellar results.

I finally got a chance to watch this particular video. It reminds me of when I used to launch my RC sailplanes with a Pepsi bottle containing two bars. LOL thanks for sharing your knowledge and I wish you had your brain

You need 2 pistons so you can get torque for the full rotation. You might even be able to fit 4 pistons

wow, it even sounds like me when i'm on a bike.

I love your ideas! Brilliant! Awesome bike!

I really thought you was going to edit a fast forward for us to see you go like road runner peeeeeowm , great video

This is much better than Elon Musk’s air powered Tesla!

Me: Wow this guy loves to work with air! Me when I realized we *Breathe* _Air_ : ಠ_ಠ

Wow! Amazing!

Always quality video productions, thank you so much. I am wondering if an off-the-shelf air tool such as a drill or die grinder could be used in place of the pneumatic cylinder. I have been curious about alternative energy storage as with compressed air or elastic power for a long time now, especially practical, real-world use as you are exploring.

You need a 7L 4500 psi cylinder!)

Just need small tank of liquid nitrogen. And evaporate it as you want.

well done.. i learnt a lot

I like how I dont understand the machine stuff but I still like to watch

I stay with my suggestion: Add regenerative braking to increase the range! :D

0:33 Where were you standing when the high pressure cylinder arm snapped that bolt?

This is really cool. Innovative!

Cool project! For SCUBA I was building a similar thruster that was to se 2 cylinders for better efficiency. (like the compressors use). 1 high pressure going from 150-75 then 1 low pressure 75-10.

I think you need a composite scuba diving bottle at much higher pressure!

Yeah nice about that range on the scuba tank but honestly I don't care. What I DO want to see is you using that full 300+ bar to go zoom real quick!

A lovely project. Good experimental analysis as well. One thing not discussed was differential volume and force of the air cylinder. Any double acting cylinder with a single ended rod exerts less force while retracting than extending. This is due to the area of the piston rod. Your cylinder has a rather thick rod compared to the piston diameter, so the difference is fairly large. In terms of you pedalling the bike, it is like having one leg stronger than the other. Because of the mechanical constraint of your drive train the distance travelled is equal for both cylinder strokes. The power, however is more when extending than retracting. In the hydraulic boat steering industry in which I was employed we eliminate this differential cylinder effect by using cylinders with double ended rods, so the power is identical in both directions.

this is nice this is something what i need for my bike

Could some creative valve timing be used for regenerative braking?

One add a furnace and water or something like that :D

The rear wheel acts as a flywheel because of the fact that it is connected directly to the engine. Since this is the case, you could make the bike more efficient by utilizing the momentum of the rear wheel and connect a one way valve from the intake of the piston to the exhaust and use the pressure from the intake to push piston back up

Great analysis

Could you run the air through a turbine and gearbox and power the bike like that? Would it be more efficient?

Sounds like a couple of asthmatics having a good time!

Make it so the bike pumps air into a tank and releases it for a boost just an idea, love your videos.

You forgot to add that the estimated travel distance was greatly reduced due to not being able to keep the bike going straight forward because of the slow pace it had. Keep up the good work mate! Even though I am a new subscriber I feel like I've been watching your videos for a long time.

Try powering it with liquid nitrogen or liquid CO2. Might need a heater to keep the cylinder happy.

Sounds like Ivor the engine - probably before your time 🤣

Mint. Thomas the tank bike. Just needs a pump or home brew compressor that works when peddling to recharge the tank. Brilliant job by the way.

Silly me. I commented on the first air-powered bike video before watching this one. This video answers pretty much all of the questions I posted on the first. At the end of the video, you compared energy density and performance between the air powered bike and your electric bike. You also effectively answered the SCUBA tank question. Thanks for that, I had a suspicion that the math wouldn't work out, but you actually did the math (er, "maths" so sorry). Something you also mentioned which I think many commenters in the last video did not consider, was mass. Not only does it take a lot of material to contain such extreme pressures, compressed air weighs a lot more than just "air." I think many people have a common-sense concept that air is weightless. Thank you for explaining that it isn't. Comparing energy densities, however, one bit was left out: Comparison to carbon based fuels. You mentioned this in your atmosphere powered RC car. There's a reason we're having such a hard time moving away from gasoline/petrol, diesel, coal, and the like. They're very energy dense. A litre of petrol will do much more work than the equivalent mass of even the most efficient battery, and much much more than the equivalent volume of compressed air, given the limits of the technology required to compress and store that air. I own more than one motorcycle, my littlest one has a very small fuel tank, and will go about 110 miles/175 km before refueling. Eyeballing the size of the tank on your air bike, I expect if I had that much volume as gasoline/petrol, I'd get something more like 400 miles/ 645 km. So... one hundred times more than your theoretical maximum? Oh, also at much higher speeds, say 70-80 kph (it is a really small bike).

Did you mount the piston with bearings? To prevent power loss.

methanol fuel cell bike it's... even rationally))🤔

The effectiveness of this project was inversely proportionate to the entertaining value of this video. Keep inventing !

Brilliant. A way to make it more efficient is to be able to reverse the piston valves so when you are going downhill you can recover energy or even the way F1 cars recover energy, when you brake you also reverse the piston and compress more air back into the cylinder. This is just talk from someone inexperienced like myself though. Hats of to you for making this in the first place

Cant wait for reaction wheel drone pt 2

Love your work tom. Please grace up with plutonium powered windscreen wipers next 😁. Cheers

Tom: The more power you output, the less range you have SR-71: Am I a joke to you?

The trick to extend range in pressurized air vehicles is to use really high pressure bottles, then a first pressure drop to chill the air near freezing point of moisture in ambient air (or well under, but it requires a rotating brush to remove the building up ice). In such a way you can recover energy from ambient air to increase pressure of the plenum before reducing it again to activate the piston. Other than that, short stroke pistons with big bore are preferable, since they have bigger force with less pressure, thus decreasing both friction losses and exhaust losses. Applying a diffuser on the exhaust port decreses a little dicharge pressure for a little more bonus

i should be study mechanism II since i have the partial exam on tuesday but instead here i am, watching a guy being the engineer i will never be.

Get the exhaust to go into another smaller valve/piston, that's has its gear ratio and all that jazz set accordingly. Then you can get the pressure closer to atmospheric for less loss. Also a valve like that isn't the most efficient design, but good work, love your content.

This video was recommended to me from a Tom Scott video.

They do make smaller pony bottles for emergency scuba divers. Also, gearing would change everything on any alternative powered vehicle. Excellent job 😉

But you have to take into consideration, that airpowered trams were roaming quite well in Paris by the end of the XIX century, as well as airpowered cars in mines at the same time. Sure, their range was limited as well, but they've had an advantage of having a better mass/power ratio due to a larger air reservoir, that in addition was transported on rails, and had pumping stations. Of course, the primary need for airpower was to produce less smoke, and electricity proved superior in this regard as soon as it became available. Paris tram suffered from another problem - due to pressure drop, the air reservoirs were freezing, with a coat of ice building over them. An external heating was needed to prevent this.

Sounds excited.

Great comparison

bet you cant supercharge your bike tom: "hold my catapult"

loved it!!!!!

Look just get a 5,000 psi tank, mount it with the valve facing backwards, and when you are ready to go, reach back and knock the valve off with a 20 ounce framing hammer. The real engineering challenge here is mounting the framing hammer to the bike with wire tether so you don't lose it. Oh and making the tank easy to remove since you will have to replace it every time you knock the valve off. I would have done the range and power calculations for you, but I don't have a envelope or napkin. You're welcome.

you should trick out your homemade ebike with more small projects like the abs system! (Ex. power steering, dashboard, gyroscope.)

Air or pressure powered vehicles actually did see success in one field. Fireless steam trains, these were used for shunting and short transport at factories throughout much of Europe during the turn of the century, the reasoning behind them is that the factory usually already had it's own steam engine so for work around it there was no need for the train itself to carry one. The train would then instead of a boiler just have a huge tank for storing steam or pressurized air and recharge at the factory's steam engine.

Cool, very cool.!

The pneumatic cylinder looks quite large and the amount of air used per cycle seems quite low. If I aim for a lower estimate than what it looks like then the diameter of the piston is 30mm,stroke length is 200mm and is operating at a constant pressure of 6.85 bar(100psi). Formula used for calculating amount of air used is Q(litres) = Area x stroke length x 10 to power of - 6(as using mm) x [6.85bar + 1bar(assumed exhaust pressure)] This comes to pi x 15mm(squared) x 200mm x (10 to power of - 6) x 7.85bar = roughly 1.1 litres. That is just for the forward stroke and return stroke will be slightly less when deducting the piston rod diameter from piston diameter but per cycle comes to just over 2 litres. I feel like the stroke length and piston diameter is likely more based on what it looks like so this number would be even higher if that is the case. I noticed when operating at 100PSI the video states that 1 litre of air is used per cycle which seems really low considering how big it looks. Perhaps I'm completely wrong in my assumptions but just seemed low. Can anyone help me clarify this?

I work for festo. They did this experiment 30 years ago and got 700 metres out of a tank at 6 bar pressure. Air is extremely inefficient, costing up to ten times more than the price of electricity. Vds and vsc compressors have increased this efficiency to 25%. By adding heat retrieval from the compressor we can improve the efficiency to 10%

I came here to see a test of an air powered bicycle, instead I got a Physics lesson. GOOD SHOW, Mate! CHEERS.