Matthew Perez, a Mechanical Operations Technician for the Virginia Tech Transportation Institute, sent me some details of a design he’s working on, he was a little tired of seeing only electric motorcycles when someone mentioned alternative fuels and he thought he would come up with something that would carry him back and forth to work, a trip of 10 miles each way so he developed this air powered motorcycle concept.
The AirHead engine is the center of his design, everything else seems to be doable and Matthew has much of it worked out. The compressed air is held in 4 standard SCUBA tanks, the frame and suspension all pretty much as you would expect.
So what about the engine? Since Matthew sent a lengthy explanation, I’ll let him do the talking:
I designed it from the ground up removing all the things that rob an engine of power. There is no charging system, no oil pump, no transmission and most importantly no over head valves. Everything rolls on sealed ball bearings. The gears in the bottom end for the balance shaft and gear reduction are in an oil bath and the output is essentially direct drive. Omitted from this design was an external dry clutch pack but will be included in consecutive revisions. The cylinder is offset as opposed to centered over the crank for a better rod angle on the power stroke. The cylinder and rings, since they don’t need to support the heat of combustion, will be a composite or ceramic setup most likely. Possible additions will be an air jet supplied by the exhaust tubing which sprays the oil bath on the cylinder walls if needed for cooling and wear resistance. Intake/exhaust is controlled by electronic 24vdc solenoids. This allows the motor to be extremely versatile as well as a 2 stroke having a power stroke every revolution.
The solenoid valves serve many functions. The bike is setup as a drive by wire system. The ecu reads input from front and rear wheel speed sensors, the throttle and the two crank sensors and determines pressure, time and duration. There can be predetermined power level settings which will restrict the max pressure anywhere from 150psi to 750psi. During engine braking only the exhaust valve will be operated and can create back pressure based on bike speed, throttle position and brake pressure. The solenoids are the life-blood of this design. Without them you would not be able to have 700+psi entering the engine because a typically poppet valve/spring setup could not hold this pressure.
In addition to the engines normal function there are plans to use it as an air compressor driven by an onboard electric motor which can be plugged in. During this process the operations of the solenoid valves will be reversed allowing the engine to pressurize the tanks. To reach tank pressures an additional booster piston may need to be added to the assembly. The on board electric motor would also be used for regenerative braking to recharge the battery.
Another interesting point is the rear brake:
There is no rear brake pedal and the rear brake is actuated by the Ecu based on a few inputs. Front and rear wheel speed, front brake pressure and the chassis attitude based on a 3 axis accelerometer mounted in the ECU. This removes all foot controls from the rider as well as giving the Ecu control over rear wheel traction.
As with all design concepts like this, the real test occurs once you begin making hard parts and find out if things work as planned. There is obvious work to do here but it shows some interesting lines of thought.
Any air powered machine, in order to be practical, before actual performance is even considered, is some sort of on board compressor, Matthew took that into consideration here. The ability to recharge high pressure cylinders anywhere along normal roads and streets is pretty minimal. If you have that, then the air engine needs to give you enough performance to make the design worthwhile, his targets are 100 mile range and, for short periods, the performance of a current liter bike. Considering the engine is still purely theoretical, we’ll have to wait and see.
Matthew designed this bike to meet his short range commuting needs which is a natural place for any of the alternative energy motorcycles we’ve seen so far. Once you get out of the city or commuter environment, the old liquid fueled internal combustion engine is hard to beat and it gives the developers of these motorcycles a goal to shoot for. We’ll keep watching to see how these plans work out.
iliveforcurves says
I like the idea of storing energy as compressed air instead of an electric battery. There are no big batteries to replace with all the problems of disposal or recycling. I know of a French company that has made a compressed air powered car but this is the first time I’ve heard of anything like this in the U.S. I think part of the reason is the NIH (not invented here) syndrome.
scritch says
Since this type of engine is essentially the same as a steam engine, minus the heat, why not use double-acting pistons?
Walt says
Interesting idea. I’m wondering how much potential energy is unleashed as a diving cylinder’s contents are channeled through the motor. I found this on Wikipedia: “So a 12 litre cylinder at 232 bar would hold almost 2784 litres (98 ft³) of air at atmospheric pressure. In the US and in many diving resorts you might find aluminum cylinders with an internal capacity of 0.39 ft³ (11.1 liters) filled to 3000 psi; Taking air pressure as 14.7 psi, this gives 0.39 x 3000 / 14.7 = 80 ft³.”
I don’t know how to proceed from here to calculate the energy available. The practical value of the whole system will depend on the the energy available in the tanks and the motor’s efficiency in converting it into torque/horsepower (range and power) and the energy required to fill the tanks with air compressed to 200-300 bar in the first place. We don’t know about the motor yet, but I’ll bet we’ve got people on this list smart enough to figure out the other factors.
Bazuzeus says
Wow… you’ll look so “green” with this bike… well at least for 7.3 miles ^^
Jorge Pullin says
Well, the most advanced types of containers for compressed air have energy densities comparable to a lead-acid battery. So it appears this technology has a long way to go,
http://en.wikipedia.org/wiki/Compressed-air_energy_storage#Energy_density_and_efficiency
There are lots of people out there playing with this technology, e.g.,
http://compressedaircars.homestead.com/Aircars.html
Matt says
Well guys this is my design here and range obviously is the biggest concern when talking about these concepts. The bike holds the 80cuft as mentioned at 3000psi. The key to the system is variable pressure. The cylinder is large at 720cc but the small “combustion chamber” volume and timing the charge is key. Having full control over the air is where its at. Ive only been on this project for 2 months so I know there are plenty of details to work out. Thanks for looking.
Mechanicaldan says
An air engine isn’t the most efficient method of energy conversion, batteries are better, but I don’t think that’s the point. Coal + losses = electricity + losses = compressed air + losses = forward motion. Likely this is a design/control exercise of a new air engine design.
The ECU mapping will be a pain to get right. With the engine at rest, the intake solenoid needs to open enough to get the piston to move downward, and with a single cylinder, starting the motor backwards could occur if the crank stopped on the upward stroke of the piston. If luck allows the crank to stop on the downward stroke of the piston, then the intake needs to close just as the piston reached BDC and the exhaust remains open hoping there is enough crank momentum to carry the piston back past TDC. This is why the engine will need a clutch, and hopefully not an electric motor to start the air engine. Will an alternator be connected to the engine to run the ECU and solenoids, or will the battery be constant drain and require charging also?
I feel a constant expansion rotary type motor or engine would be much better to use for an air application. Something like a rotary vane or quasiturbine arrangement. You could mount one of these types of motors directly into the rear wheel, and get rid of the clutch, chain and sprockets and starting problems. Of course, that’s also more difficult than just putting a engine in a frame and connecting it to a readily available wheel with a chain and sprocket.
Being at a very early design stage with few details, there are lots of questions, and likely very few answers.
It is interesting and thought provoking.
nortley says
Compressed air motors worked well enough on torpedoes, even better when the air was heated between tank and motor. Another use for that air reserve might be to direct some of it to an active suspension which would allow the rider to hop over traffic obstacles.
Tim says
It is interesting. What if there were pedals to manually provide compressed air to augment the system? Is that even a practical consideration?
Matt says
Thanks for all the comments. Mechanicaldan you are very right and all are very real concerns. The inital idea is that on decel when the ecu senses no throttle input the exhaust valve would be held open as a sort of “freewheel”. The on board electric motor would be used in a regen braking arrangement to both charge the battery and provide some braking forces. Stopping does have the issue of motor position. The motor has two crank position sensors and once the rpms are to a certain point it can stall the motor but this really isnt the best solution. Another idea is using the E-motor to ensure the cranks position is proper. Without the Emotor it would be a tough problem because shutting both valves will add un-needed stress. These are all issues that have to be addressed but farther down the list to sort out after the decisions are made as to the feasibility of the motor layout and so on.
Jorge, yes you are correct but that is only part of it. You have vehicle life, complexity, weight and so on. The simplicity of the air motor is greater(and much less expensive) than an electric motor and controller. The environmental impact of the production of batteries is a consideration. The potential hazzards of the different design in a crash.
jokermtb says
I believe White Castle is interested in sponsoring an Air Powered vehicle….
Tin Man 2 says
Great project, very thought provoking. I look forward to updates as the plan moves along.
todd says
This is really cool. I had an Air Hogs plane that had all mechanical valves. It worked great and had a flight duration that would rival a capacitor powered plane. Altitude was far better because of the lighter weight.
I’ve ofter played with the idea of a motor powered by dry ice pellet sublimation, or maybe liquid nitrogen. Pretty much a steam engine at lower temperatures.
As far as starting goes, the energy of stopping could initiate a recoil starter. When you were ready to start again, you would press a button (electrical or mechanical) to release the stored energy and start the motor. A centrifugal clutch would be helpful.
I hope someone (Air Hogs?) gives this guy some some seed to get a bike built.
-todd
GenWaylaid says
Walt,
The maximum energy in the tank is the product of the tank volume and the change in pressure as it is discharged. E=V(P_0 – P_1). For this bike, V = 80 cuft = 2260 L, P_0 = 3000 psi = 20.7 MPa, P_1 = 0.1 MPa. Therefore E = 46.7 MJ = 13.0 kWh. However, bear in mind that the conversion efficiency will be very low, definitely below 50%. Perhaps only 3-4 kWh is actually available to move the bike. That compares favorably with any ~$10000 electric motorcycle you could buy today, but charging efficiency for compressed air would be much lower.
Redman says
Definitely a neat concept. And while I prefer the look of a naked bike, one would think that a fully faired version would improve aerodynamics and translate into greater range.
Wave says
A very nice concept! As an engineering student I find this extremely interesting. One thought that I would have, is that if you have a sufficiently high-torque electric motor to move the bike and rider from a standstill, you could presumably do away with the clutch entirely. You would not need a large battery or a very large motor, just enough to get the piston of the air engine to TDC in forward motion when starting from rest. A regular motorcycle starter motor would be sufficient, and could be disengaged once the air engine has started. Regen braking could recharge this small battery. I realise that you’re trying to do away with electricity as much as possible to simplify the design, but I think that some sort of electric start would be beneficial. Either that, or the rider could simply scoot it forward at every traffic light to get it going!
Also, if you have one would the dry clutch be manually controlled? I’m thinking that a motorcycle rider would tend to slip the clutch far too much to be optimal, as really you only want the clutch to engage until the correct crank position is reached, if I understand correctly. Steam engines seem to have overcome the problem of starting position without clutches or external assist, perhaps you could take inspiration from them? I assume that with a single cylinder it would have to be double-acting to allow pure air-powered starting from every engine position.
Paulinator says
Yup, this is really cool – and timely. I just read about a Chinese control on stocks and production of rear-earth metals needed for (you guessed it) hi-tech batteries and electric motors.
When I was a paper-boy I had a tiny little CO2 powered engine that worked great with piston ports and a check valve in place of the glow plug (that the piston tapped at TDC). A key to it’s performance was good airflow over the in-line warming coil and the cylinder’s heating fins. Just think about all the heat that is squeezed out of 80 cu ft of air when compressed to 20 bar at room temperature. Universal gas law factors in pressure, volume and HEAT. Let the system pull that heat back in from the atmosphere and significant improvements will be realized.
Matt, for the engine I’d consider using a material that has low weight, excellent heat transfer, easy processing and attractive cost. Any ideas?
David/cigarrz says
@ Tod I agree, seed money has been wasted on far worse ideas. I have seen the air car on TV and the air hogs so on the face of it maybe a motorcycle is a very workable scale. I am still working my way through the mental gymnastics concerning the motor and controller but its as worthy a project as electric power
Matt says
Redman, im not worried about aerodynamics because this vehicle is aimed at lower speed around town travel(at first). So fairing would be extraneous since the losses will be out of its speed range. I do have the ability to add several more tanks at the downfall of increased weight due to framework needed to protect the tanks. 160-200cuft is very possible and fairings might be a consideration just to hide them.
Wave, the clutch was mainly as a safety feature. with a motor that is directly coupled to the drive and completely controlled by the ecu there needs to be some sort of method to decouple in. I think in a post above i mentioned the Emotor could be used to “nudge” the bike from a stand still. The current setup is only single acting but its also only a first revision. I have toyed around with several ideas and nothing is off the table yet. The current direction Im toying with will incorporate some rotary action but im not saying much more until my first concept is drawn up. I have to keep some tricks up my sleeve 🙂
Paulinator. The heat generator by compressing the air in the tanks will have to be monitored and dealt with for sure. When the air expands it will cool and hopefully cool the solenoids as well as some other things possibly through heat exchangers. The drawings above are slightly simplified from some other concepts i have in mind. As far as materials go i would really love to use composites but im not sure that any resins will hold up so it would potentially be a composite cylinder with ceramic coatings. But again the piston engine may turn out to be the wrong avenue all together but i need to travel down it a ways before I decide to turn around and some of the additions that i havent mentioned will certainly make a difference.
David. I do have a simplified non-adjustable version that i first started working out. It involves essentially “triggers” which fire the solenoids depending solely on engine position(with mechanical advance) and a throttle governing pressure regulator. This would eliminate the ecu from engine control at the expense of possible efficiency gains. Its very likely that early prototypes will see very simplified control systems.
I know the main benefits of a system like this will not include range, that’s a given with current technology, but technology will never improve if different ideas are pursued. Compressed air is an easily attainable source for every consumer and that’s the big focus and selling point. Anyone can plug in an air compressor and convert their electrical energy(be in from wind, solar, water, coal and so on) into its storage in air tanks. Finding a way to efficiently put that to use for travel is what i’m after and I appreciate all the commentary that this has brought. I think an air powered bike is not only feasible but it will out last its electric counterpart and be much less expensive to produce and maintain making it an easy jump off point.
Greg Jetnikoff says
If you were a bicycle rider you would know that even at modest lowish speeds air drag plays a real part so a working fairing would extend the range substantially ( including REAR fairing , the forgotton drag). beyond as little as 24kph drag becomes noticeable and the only real limit on speed is air drag.
What about a glass ( perhaps whisker reinforced) cyl in a carbon composite barrel with a ceramic or high temp plastic ( again reinforced) piston.
A novel idea if you have a clutch to overcome the piston position … a simple “kickstarter” if you use a clutch.
Or a twin opposed config with common pin . In a “two” stroke one cyl would be always be in “power” position. Not high electronics required to supply air to the correct solenoid.
The drawing also shows huge tyres. Great on a megabike but not necessary on a commuter bike and they have WAY too much rolling resistance. If fact higher pressure narrower and lighter tyres would be a huge advantage.
Great basic idea though. Any alternative avenue in currently worth exploring. Does it qualify for the TTXGP ( not being electric)??
todd says
Check out “CoolPoly” for thermally conductive plastics – yes, plastic heat sinks:
http://www.coolpolymers.com/dseries.asp
-todd
Greg Jetnikoff says
Actually I just had another thought. Considering the expansion involved, does this engine release heat or does it get ridiculously cold ( read freezing). Has anybody played with this sort of motor. It may actually need a reverse heat flow and under those conditions you would be getting more power from the heat obtained from the surroundings. Ie you may need , say heatpipes in the head to transfer heat IN. Or have I missed something.
WRXr says
Why not go fully pneumatic and install air shocks rather than a hydraulic for and rear dampener. I believe the BMW HP2 GS uses a pneumatic rear dampener and post war Sunbeams used to have Pneumatic forks
Harry Mallin says
@Greg Jetnikoff – no, this bike would not qualify under the TTXGP Technical Rules, because currently only electric bikes are allowed. However, if someone wanted to amend the rules to suggest the inclusion of air-powered bikes, it is now possible, as TTXGP just put its rules up on a wiki for public input. Go to the website for more info.
Matt says
Greg, you are right that aero does play a part at all speeds but for the majority of 0-30mph the addition of fairings i believe would be negligible. I havent had a chance to do any fluid simulations on the bike but my hope is partially that breaking up the air will help reduce the drag on the back end(since the bike is so short) but really not too high up on my concern list since the body is an easy change. The tires, you are also right there. The drawing is a concept to attract attention. An agressive “beefy” looking bike in my eyes demands a little more attention than something running on tiny rolling stock. My commute(which is what this was planned for) is about 10 miles of windy back country roads and i make the most of my tires. For the masses this would not be ideal but thankfully in the real world that is a very simple change.
I like the glass idea, i will have to do some more research into it.
And yes I do believe lower temps and condensation will be prevalent in the design and heat less of a concern. Even with different materials at hand there will still be heat generated by the friction of the seal in side the cylinder. Whether heat will need to be removed or added to the cylinder hasnt been determined yet. The solenoids will need to be cooled and my hope is that the cylinder temps will be low enough that i can use the difference between the two to help balance things out through conduction.
WRX, i didnt want to spread the air out for other functions besides the motor. There was really no reason to redesign any suspension components for this design. Ive owned bikes with air assist suspensions and antidive and honestly i prefer and simple, lighter conventional setup.
again thanks for all the comments/suggestions, please keep them coming
Spartandude says
Due to thermodynamics you will get more efficiency if you allow heat (energy) from the surroundings to heat the cylinder and air tanks during use. The friction generated by the piston will not offset the extreme drop in temperatures that the engine will be faced with. Any time you expand the volume and drop the pressure you will have a corresponding drop in temperature. You will need to manage your heat transfer for this engine to insure that it does not frost and choose your oil bath lubricant carefully to insure the viscosity at the temps reached does not detrimentally affect performance.
One could do the heat transfer with air fins or with a radiator, but the latter would have issues with fluid choice. Oh, maybe have the lubricating oil circulate through the radiator, into the oil bath then up the cylinder walls.
Personally, at only 10 miles, I say efficiency be D***ed, keep it simple. I would insure my compressor dried the air really well, run mechanical links to operate the valves, thermally isolate the oil bath and run down the merry road.
Check out ToughMet for a really cool bearing material that may allow options for linkages without lubrication.
I like the concept and wish you luck.
Thanks kneeslider for this find. It is the first concept in a while that got my brain working.
Justin says
Maybe you could use the scuba tanks as the frame or the frame as the air tank, but the development costs would be high. I love this idea and you deserve to get support for it.
AJ says
I wonder if you could have some kind of scavenging pump after the power stroke to reuse the pressure and make it a closed loop system. We are really not looking for high performance here,the equivalent of a 50cc scooter like i use for inner city commuting would be perfect, 30mph top speed.
Walt says
Matt,
Any thought to creating a multi-stage motor? That might enable you to extract more energy from the compressed air, in the reverse of the way a two-stage compressor works. There’s interesting information in the links Jorge Pullin provided above.
Matt says
walt, yes i have and thats part of my un mentioned development:) There was an initial idea of a smaller piston and a larger piston which would essentially be used to recompress the air while plugged in but could be used in reverse of that. Im affraid that the losses would be too great in terms of using that to drive the vehicle but i have a few other ideas for multi-stage motors that i will release when the time is right.
Justin, i want to shy away from using the tanks as a structrual component for safety reasons. The stresses associated with a pressure vessel are fairly easy to control but once you add in the associate frame stress you introduce a problem.
AJ, once the high pressure air enters the cylinder it has “explosive decompression” as it achieves atmospheric pressure. While you could potentially recapture some air by keeping the exhaust valve closed for part of the stroke or under decel it would be at a very low psi and probably not very effective. Also it takes HP to compress the air so any power used for that is being taken away from another function. It is a great idea but physically impractical.
todd says
I’m thinking you probably won’t need lubrication. You won’t have any fuel vapors that wipe cylinder walls clean or combustion process that burns it off/acidifies the oil. You could use self lubricating polymers for the cylinder and ceramic or carbon, graphite bearings. Gears could be simple nylon. I think you’d just need a little light grease (lithium or graphite powder) for the gears. Oil would cause too much parasitic drag with little benefits.
Self lubricating polymers: http://www.cipcomposites.com/index.cfm
-todd
pabsy says
Matt
What a great project and great comments, its just for projects like this I visit kneeslider
Justin has a great idea to use the tanks as frame and they don’t require service or removal, additionally the idea furthers your commendable drive for simplicity
Taking this one step further why not build a single frame/ tank from say a 10″ (about) diameter pipe backbone-chassis style
The tube would go from headstock to butt to swing arm with just one curve of about 15″ inner rad. A quick calc and I think you would be suprised at the mount of volume versus the 4 tanks currenly, every inch in outside dia yields big volume dividends
Cap the ends and weld on the ancillaries such as headstock, motor mounts etc, you can even plate the inside for a reserve chamber
In any case great project and love the motor concept
Pabs
Shawn says
This is great. I never was that happy with the thought that the future would be with electric vehicles. My main concern was with the battery as the storage and energy unit. The life of a battery is limited, the manufacturing proccess of a battery uses materials that are not easily recycled and then power output (distance per power output) is limited. This concept has huge potential. This has me very excited. Now I’m looking forward to the future
Matt says
Thanks for all the great comments.
Todd thanks for that link. the CIP300 looks like a very promising material. It has a very broad temp range and its dimensional stability is great for this application.
Pabsy, i agree that the volume obtained by a frame/tank would be far greater than using these tanks but the ability to use composite tanks has its own benefits. I really want to shy away from the pressure vessels as a structural component at least initially but its not out of the ball park. But having said that a 10″ back bone tank would cause a rethink on motor mounting which is not an issue, but also raise a weight concern. If i were to use steel with an adequate wall thickness it would be on the order of 30-40lbs/ft. Considering the fact that the wall thickness will no longer be consistent. I do think on a production level these might be considerations but unfortunately at this stage it is much easier to keep the tank/frame as separate members and utilize available parts when possible.
Peter Lankreijer says
The project looks really nice! Keep up the good work.
One comment on the “green” side of the concept. In the comments, it is compared to electric concepts but there is a big difference in total efficiency.
Offcourse, in the bike itself it is as green as it gets. The problem is to get the compressed air. Air compressors are about the worst pieces of engineering there are. For my work, I had to ventilate compressor rooms on offshore-vessel. The efficiency is in the range of 5 – 10 %. This is not the loss, but the efficiency itself. 90 to 95 % of the energy is converted to heat! The concept will use more fossile fuels than a conventional engine.
pabsy says
Hi Matt
Yup definetley several ways to go depending on your goals, I thought with capacity / distance travelled bieng a major issue this might be an option to add capacity with the lease amount of added weight
I sphere would be the most efficient shape but presuming you dont want to ride around on a big old ball a big ass tube would be the next best thing for not only weight but integrity
Not sure what you mean about wall section it would be very even, aluminum would be great but if that were such a good idea they would use them in scuba tanks, porous maybe ?
In terms of complexity though if you factor in the balance of components, this would be the least complex.
great stuff keep us posted
Thom says
Would it be possible to use the engine as a compressor during decel only? That would give a measure of “engine braking”, and usefully increase range, don’t you think? I assume with electric solenoids and computer control, it wouldn’t be too difficult to work out how to do it… Just a thought.
joe says
In India sometime in 2007 they designed and produced a small air powered car.In fact, I think they already use some of them as Taxis.
Matt says
joe, yes i know about the air car. i think i mentioned it somewhere here. The car has the advantage of holding several large tanks and they have an on board gas powered compressor.
Thom, yes you could but the pressure gained by using the engine to compress air under decel would be less than useful I would think. It was initially on the table but regenerative braking by use of the Emotor to charge the electrical system seemed like a better use of the energy.
Pabsy, the comment about wall thickness was from the bending of a tube to make the frame. From your comment i thought you were saying a large diameter tube that was bent over a large radius for the back bone. If there was no bend this wouldnt be an issue but the weight is still there. Typical scuba tanks are aluminum(cold extruded). A smaller majority of them are steel. Composite tanks arent really used as far as i know for diving.
Peter, thanks for the comments. It was never my intention to have this bike directly compared to an electric bike by means of efficiency. They are really two very different ends of the spectrum in so many aspects except the Alternative arena. Price to produce, weight, longevity and so on. The end design(hopefully) will be multiple stages to increase efficiency. Most likely 3 or more stages and unfortunately probably double acting engine which complicates things a little(if it stays with this style engine). I still have several ideas to play with but the 5% efficiency number seems a good bit lower than whats possible(hopefully). There is an inherent inefficiency in charging batteries in an electric vehicle but both the EV and air powered vehicle would initially be charged off the power grid. Without a finalized motor concept I have no idea what the price to charge will be or range so there is really not anything to give a valid comparison between the two.
Scotduke says
Very interesting idea – in the mining industry compressed air locomotives have been used in some underground coal mines where there is a risk of gas in the rock strata. Range is an issue with these locomotives and I don’t think tehre have been any manufactured for some years so the technology would be somewhat antiquated.
todd says
I’m a little out of my league with this question but;
If you add water to the compressed air would it act as an additional propellant against the piston? The expanding air would force the piston down the cylinder but water (having greater mass) would transfer some of the kinetic energy of being shot out of the nozzle to the piston. I’m sure it would complicate your exhaust and there might be a potential for water lock-up at TDC if it wasn’t all evacuated. Hmm.
-todd
Matt says
todd, since there is never a compression stroke there should be no issue of hydro-lock but i think water would only slow things down. Since air cools when it expands you would potentially have a freeze issue. Im not really sure that adding water to the mix would help out all but I dont know that for sure. Its certainly an interesting idea.
Peter Lankreijer says
Matt,
Thanks for your reply. I was aiming at the comments of other people that were comparing the concept with electric vehicles. The efficiency I mentioned is not the efficiency of your bike, but the efficiency to compress air using the power grid. A compressor is generating a lot of heat by compressing air.
Greg Jetnikoff says
Had another thought ( possibly a bit late now) With a single cyl motor the crankcase to maintain atm pressure will have to be completely open and allow complete in and out flow to avoid loss due to lowered differential between both sides of the piston ie crankcase pumping). An opposed piston setup with the same DISPLACEMENT ( not necessarily the same bore or stroke , may allow a more closed ( but not sealed due to blowby pressure buildup) crankcase . In that case you may as well use staged pressure drop . This would also allow less cold problems as each cyl would share the temp drop and also increase the surface area for heat flow to the cyl. The real trick would be the correct calculation and shaping of the chamber/manifold between the two cyl . That would also give an oportunity to introduce heat to the expanded air from the first cyl before it enters the second .
Maybe even two expansion chambers if you use bottom of stroke exhaust ports to use the sonics of the blowouts.
This is a seriously interesting idea overall, I like it .
Compresses air is the biggest hurdle ( or at least it’s production) We need some ideas on that one as well to reduce energy use for it’s production. Waste energy ideas anyone?
Mark Speed says
I love this concept but RANGE is the real goal. And I think lots of the comments about aerodynamics and small engines are eluding to that unsaid goal.
I don’t think starting is an issue. I know the old steam locomotive always seemed to start up the direction the engineer wanted- so study them a bit.
I also agree that you want warm (or hot) cylinders and especially heads. This will help the [cold air – yes it will be very cold] to expand further. Don’t add water, you don’t want ice!
I like this ideas ’cause you can re-fuel MUCH quicker than electric (and you don’t have those nasty batteries to dispose of after 5 years). Maybe solar can be used to pump up the tanks (a little) while it sits for 8 hours a day in the sun???
Matt says
Hey mark. Solar panels on the body were an initial idea for daily recharging as most bikes sit out during the day. I also had the idea of solar charging stations located at parking locations. This would allow for much larger solar panels. I dont know enough about solar panels to really know what will work or not. I know the small dash boar units put out very low current which obviously isnt enough to generate the HP needed to compress the air at these levels so its one of the things on my “want” list.
I am still trying to work out engine details but no real progress has happened yet. I have a few directions I am heading and as soon as I make any real measurable progress I will try to update some pictures.
fred harmon says
Yes, it would work, I’ve thought about this design or at least the general concept, but being a scuba diver I would be concerned about that 360 cu. ft of potentially explosive pressure- my brother has a scba tank he uses in confined space recovery classes he teaches and its a scarey thing to look at- its ripped open like a twisted coke can.And park in the shade, cousin, the sun will make that a bomb. So, protect the first stage valve, paint it white, bring it on, I volunteer! Keep up the good work kneeslider! My only complaint is you are toooo looonnng between fresh articles, Im gobbling ’em up like a starving man, only to have to wait for my next tidbit! Hey, do you accept articles from readers? I’ve got a cat in the neighborhood y’all might be wanting to check out! Thanks for all you do-Fred Harmon. fharmon@wowway.com
kneeslider says
@ fred harmon: “My only complaint is you are toooo looonnng between fresh articles, I’m gobbling ‘em up like a starving man, only to have to wait for my next tidbit! Hey, do you accept articles from readers?”
Fred, I hear you. Unfortunately, there are times when the offline world intrudes and demands huge time commitments, something which I am facing right now. I am doing my best to keep up the pace but it may be just a little while before we are back to normal.
If you have an idea for an article, send me a few details in the contact form. I’d be happy to take a look.
Matt says
thanks for the comment Fred. I did some calculations on pressure change due to temps. I dont remember the exact numbers off the top of my head but I think it was around 60degree change in bottle temp was around 100psi. The tanks would need to get very hot before any real danger was possible from increase in pressure. That, burst discs and the fact that air heats up when its compressed, but when sitting still they will cool and the pressure will drop, i dont see it as a real issue.
Tank safety is extremely important though and thats why i felt the need for the frame to surround the tanks.
No exciting development on this as of yet. I am playing with multiple ideas but none have really won me over just yet.
Telekom says
Matt, really interesting work. I wonder about the placing of the tanks. They’ll be heavy, so maybe they would be better placed where an ICE engine normally sits to centralise mass. The bike looks top and front heavy – high COG. Great idea, keep it going and good luck.
rafe03 says
Great new thinking, Matt! Talk about outside the box!
Couple of thoughts:-
— Head off down to your local dive store & have a gander at their tank filling operation. Some of them put the bottles in a water bath to keep the heat of compression under control. They use multi stage compressors (with intercoolers maybe) to efficiently do the hard work.
— Heat is definately a major concern as all that heat that had to be removed during the compression will have to be replaced during un-compression (running) Working in old pulp & paper mills, I’ve seen steam driven pumps (duplex pumps) run on compressed air & it doesn’t take long for them to frost up & then freeze solid. Same with big old steam driven power hammers (used for forging steel)
— The steam industry took many years & had many brilliant minds at work to develop & polish the use of converting heat energy into work. And it still goes on in the pneumatic tools used at your local garage. Look to Atlas Copco, Ingersol Rand, Chicago Pneumatics, etc for ideas.
— See if you have a local model engineer society around you somewhere. Those guys run live steam model locomotives & are pretty knowledgeable about the whole steam thing. They have lots of reference books about the old, really old, & newer steam tech.
— Jules Verne proposed compressed air as a power source & even had a compressed air powered helicopter in one story.
— Marine engineers from past times (& some not so very past!) also spent a lot of brain power & elbow grease trying to improve steam efficiency.
Very interesting idea you’ve got there! Lotsa luck & Lotsa fun!
rafe03
rafe03 says
Just another idea from even further off the wall. How about using CO2 as a power medium? Similar heat concerns as compressed air but at room temterature, it liquifies at about 700 psi so could be stored as a liquid! This would increase the power density inside the bottles considerably while reducing the safety concerns about pressure vessels in an accident.
Hey Matt! Thanks for stirring up the old little grey cells!
Lotsa Luck!
Matt says
Thanks for the comments.
Telekom. Weight is a valid concern but the projected weight of the project is very low. While a high CG isnt ideal the visual CG of the bike is higher than the actual CG. I dont remember right off hand but i think the weight of all 4 tanks was around 40-50lbs full. With the regulators, valving and pipe work being on the low end, the CG is on par with a current standard motorcycle. The suspension and wheels are a fairly large portion of the bike weight(proposed). Nearly 100lbs is wheel/suspension/frame, another 50 for the engine and 100 for all related air equipment. Several of my inital concepts had low slung tanks but i felt tank protection was more of a concern than a slightly shifted CG. The weight bias is slightly forward. I prefer a front heavy(52%) weight bias.
Rafe, those are very good points you bring up and thats something that will need to be addressed for sure. Id like to stay away from C02 simply because one of the main points is being able to just plug in and recharge(even if recharge times are long). I know it takes nearly 45mins to fill an 80cuft scuba tank which equivalent to the 4 on the bike. There is certainly a long list of pros/cons and give/take that need to be weighed out in a QFD. Of course until I have a concrete engine design the rest isnt really a concern.
Years back when i started thinking about alternative energy my first direction was steam, but my ideas were power hogs unfortunately but I really need to look back into the things you mentioned.
Again thanks for the great comments. Hopefully I will have some new ideas to share soon.
Matt
Scott Plourde says
Very thought provoking I love R@D .I would be intrested in building the frame, and chassis for this creation have all the tooling I also think outside the boxs as too say a craftsman. We could build the frame too be the tanks and the swingarm .Also airsuspension for the plush ride all in one tank in the swingarm .At this time I hold a really cool patent on a nodowntube frame built for V-Twins ! You can see the patent if you look up cantilevered frame under patent applications! Keep pushing the dreams until it becomes reality!
kundan bonde says
I am interested in making prototype of air operated engine. So, would you please give me the details about how can I make simple model of air operated engine. Also, please give me details such as design of storage tank, piston, cylinder, connecting rod and information about total assembly.
todd says
I am holding US$10 million for you in Swiss bank account. If you only send me check for 10% of that I release funds in your name. Please hurry…
Right after you give Kundan Bonde all your ideas you should go ahead and post your social security number on here too. Don’t forget your mother’s maiden name.
-todd