Yostumpy Posted May 28, 2008 Share Posted May 28, 2008 Hi I've got an over active mind, and too much in my head!!!! (OR MAYBE NOT ENOUGH) Is it feasible, (not that i'm going to try to build one), seeing as a deisel engine is HIGH COMPRESSION, to have a small but powerfull donkey engine in the back linked to a very high out compressor, and run a deisel engine on compreesed air. Obviously the fuel pump would need to be replaced with an air regulator device. Would the engine need an eccentric crank so it didnt have a dead spot when initially starting off? I know that on this forum more than any other some of you guys create the most amazing things from string and sticky back plastic. I also know that the French ( I think) are hoping to have a production small car running on compressed air very shorttly. just a thought! Quote Link to comment Share on other sites More sharing options...
muzaz Posted May 28, 2008 Share Posted May 28, 2008 I dont think it will be feasable... never heard of air driven vehicles... hydraulic yes tho, usually its heavy plant like cranes etc Quote Link to comment Share on other sites More sharing options...
Bull Bar Cowboy Posted May 28, 2008 Share Posted May 28, 2008 One of the golden rules of physics .............. 'you cant get something for nothing' Even if it were possible , then the engine driving the compressor would need to be more powerful than the diesel due to the conversion losses ..............so you would achieve absolutely nothing apart from the extra weight of an engine that would require even more HP then the original.................own goal really....... TBH this suggestion is even worse than the clown who wanted to NOS a 300tdi .......... Ian Quote Link to comment Share on other sites More sharing options...
rtbarton Posted May 28, 2008 Share Posted May 28, 2008 No chance. If anything you'd need to feed the compressed air into the inlet manifold and modify the valve timing to omit the compression stroke. I wonder if it would work if the cylinders 1 & 4 and 2 & 3 were connected by pipes? I'm too tired to work it out at the moment. I think Tata are devolping a compressed air driven car, I started a topic on the International forum. Quote Link to comment Share on other sites More sharing options...
LandyManLuke Posted May 28, 2008 Share Posted May 28, 2008 "the 'wrong end of the stick' award goes to......." Yes tata and a french company are jointly developing a compressed air engine, but the principles of that, and what you're suggesting, are at polar opposites to each other. Quote Link to comment Share on other sites More sharing options...
TRMV8 Posted May 28, 2008 Share Posted May 28, 2008 I feel this should be one to shelve keep it till your about 65+ give it to the grand kid's to solve when they come round Quote Link to comment Share on other sites More sharing options...
Yostumpy Posted May 28, 2008 Author Share Posted May 28, 2008 OOOOPPPS!!!!!!!!! that told me then!! daa dee daa! Quote Link to comment Share on other sites More sharing options...
TRMV8 Posted May 28, 2008 Share Posted May 28, 2008 Never mind move on to your next great idea????? Tim Quote Link to comment Share on other sites More sharing options...
Kim Horsevad Posted May 28, 2008 Share Posted May 28, 2008 If you really want to do something weird and un-conventionel, then what about making some kind of stirling engine, running of the heat from the exhaust? Quote Link to comment Share on other sites More sharing options...
Night Train Posted May 28, 2008 Share Posted May 28, 2008 Very large diesel engines are started using compressed air See here. Also blank gunpowder cartridges were used to as starters in the same manner, blasting the expanding hot gases into the cylinders. They were called Coffman starters. In the original film 'Flight Of The Pheonix' The crashed plane was restarted using Coffman cartridges. It's not such a daft idea but as has been said it takes more energy to make the compressed air then you would get out of the engine. Quote Link to comment Share on other sites More sharing options...
pugwash Posted May 28, 2008 Share Posted May 28, 2008 does anyone know anything about the six stroke engine that some crazy Yank was building? Bascially on the "third cycle" of a disel engine you inject water into the cylinder which immediately flashes to steam from the residual heat of the engine and you therefore get more power- because the water is also cooling the engine you also can stick a load more diesel in. More power all round basically. To laymans eyes it sounded like a feasible concept- anyone else know anything about it? Quote Link to comment Share on other sites More sharing options...
Yostumpy Posted May 28, 2008 Author Share Posted May 28, 2008 Never mind move on to your next great idea????? Tim a few years ago I had an idea It was basically to see if it was possible to blow up the tyres of my mountain bike with helium. The theory was that as rotational weight of a bicycle wheel is v.important, as roughly an ounce off the wheels =a pound off the frame theory, so if the helium negated the weight of the tubes, then a big help. Well! oh how the lads laughed, sound familiar, so I thought Bo.....x. I telephoned BOC and explained my theory, saying if it worked then maybe some spin off for advertising in races, mags etc, and then waited for the laughter. THERE WASN'T ANY.!!!!!!!!!! Hang on a moment, and I'll put you through to our man in the R+D department they said. Well after a long discussion it was discovered that one of their researchers was a keen cyclist, and he'd had a similar thought a year or so before, but on his racer. and it was found that the butyl tubes were far to porous for helium, and he had a go with latex tubes but eventually gave up on the idea! So what maybe silly idea to most, could have been thought about and researched before by someone else! SO DO NOT SCOFF!!!!!!!!!!!!!!!!!!!!!! Quote Link to comment Share on other sites More sharing options...
muzaz Posted May 28, 2008 Share Posted May 28, 2008 maybe he should have filled them with hydrogen, its even lighter thinking about it, you could make a car work on compressed air, but not by keeping the orignal setup, ie engine coupled to gearbox, gearbox coupled to diffs.... but another system where you do without the gearbox and instead couple the engine to a compressor, and feed the air to an airmotor driving the diff... I would imagine the vehicle to be extremely noisy tho! Hydraulic will be a better bet, its closed loop Quote Link to comment Share on other sites More sharing options...
rtbarton Posted May 28, 2008 Share Posted May 28, 2008 maybe he should have filled them with hydrogen, its even lighter thinking about it, you could make a car work on compressed air, but not by keeping the orignal setup, ie engine coupled to gearbox, gearbox coupled to diffs.... but another system where you do without the gearbox and instead couple the engine to a compressor, and feed the air to an airmotor driving the diff... I would imagine the vehicle to be extremely noisy tho! Hydraulic will be a better bet, its closed loop You'd be better with a motor per wheel with traction control rather than a diff Quote Link to comment Share on other sites More sharing options...
Superpants Posted May 29, 2008 Share Posted May 29, 2008 Compressed air has been used for locomotives in places where fire is an issue- paper mills and mines. They solve a lot of the problems of trying to make an electric motor operate in an explosive atmosphere. Not sure if they are still built for these purposes. They are effectively the same as a steam engine, rather than a diesel engine (as a steam engine is basically working on an expanding fluid where energy has been given to it outside of the engine). Some museums (eg science museum) run their steam engines on compressed air for demonstration. Quote Link to comment Share on other sites More sharing options...
Lara Posted May 29, 2008 Share Posted May 29, 2008 How about a Landrover powered by Szilard's engine, and with Maxwell's Demon sat in the boot! Look it up!! Lara. Quote Link to comment Share on other sites More sharing options...
muzaz Posted May 29, 2008 Share Posted May 29, 2008 You'd be better with a motor per wheel with traction control rather than a diff This is something similar we just got at work...hyd motor on each wheel, no probs with traction at all...something tells me its an expensive setup but its interesting, its so compact you can gain lots in ground clearance.. I really like those tyres! Quote Link to comment Share on other sites More sharing options...
Astro_Al Posted May 29, 2008 Share Posted May 29, 2008 a few years ago I had an idea It was basically to see if it was possible to blow up the tyres of my mountain bike with helium. The theory was that as rotational weight of a bicycle wheel is v.important, as roughly an ounce off the wheels =a pound off the frame theory, so if the helium negated the weight of the tubes, then a big help. SO DO NOT SCOFF!!!!!!!!!!!!!!!!!!!!!! Yostumpy - aren't you confusing rotational inertia with weight here? Nothing wrong with ideas - keep 'em coming! Al Quote Link to comment Share on other sites More sharing options...
Yostumpy Posted May 29, 2008 Author Share Posted May 29, 2008 Yostumpy - aren't you confusing rotational inertia with weight here?Nothing wrong with ideas - keep 'em coming! Al Well! Thank you young man!! Quote Link to comment Share on other sites More sharing options...
simonr Posted May 29, 2008 Share Posted May 29, 2008 OK, I'm probabluy not going to do myself any favours on the credibility front here....but.... I have a long standing interest in electric vehicles. The main problem with such is the energy density you can get out of any type of batteries. The ones with the lowest weight per Kwh cannot deliver the high currents necessary for decent performance. If you consider compressed air, in carbon fibre bottles, the energy density is much higher than batteries - and they can easily deliver the flow/pressure required for performance. A few years back I designed a multi-stage radial steam engine, intending to build a butane fired, closed loop steam bicycle - but never quite got round to it. The steam motor would work just as well from compressed air - and it actually solves a lot of the problems associated with different rates of thermal expansion, seals and the like. It has a good chance of delivering reasoable efficiency - certainly on a par with eleccy motors. When you compress gas, it heats up. This is the thing which makes a compressed air car hopelessly inefficient. However! If you use that heat to heat your domestic hot water & heating - at least you are getting an efficiency return on it. When you decompress the gas, it causes cooling - so at the very least, your car gets free Air Conditioning! Because you are using much of your waste heat, and the energy to heat the gas as it expands is comming from the environment - all in, the efficiency could be quite impressive! The next step is how to fill up on the road! You build an intensifier. A small air motor which drives a high pressure compressor. You then connect the air motor up to the 'free air' at your local garage. Go grab a coffee and when you come back your tank is at least a bit fuller tha before ! You could use a small wind turbie in your garden to drive a small compressor directly (giving the best energy conversion) to get some of your 'fuel' for free. My motor is ideally suited to being a 'hub motor' forming the wheel rim around the motor. Air, steam and hydraulic piston motors have the advantage that they produce max torque at zero RPM - so it may not need any gearing at all. Si Quote Link to comment Share on other sites More sharing options...
kkk2 Posted May 29, 2008 Share Posted May 29, 2008 Guys anyone watched Planet Mechanics?? They have done the air driven engine and in another episode made a working stirling engine Compressed air motorbike K Quote Link to comment Share on other sites More sharing options...
TRMV8 Posted May 29, 2008 Share Posted May 29, 2008 The only problem with a scooter is by th time you get two 8274's, waffle boards and your Co driver on, your power might be lacking???? Quote Link to comment Share on other sites More sharing options...
rtbarton Posted May 29, 2008 Share Posted May 29, 2008 OK, I'm probabluy not going to do myself any favours on the credibility front here....but.... Si I've been thinking on these lines. You could recharge the receiver to some extent on braking. Compressed air filling stations could be incorporated in buildings that use a lot of hot water, laundrettes, hospitals, eateries and so on. If you have a system with a donkey engine you could feed the heat from the engine to the motors to increase efficiency, also the engine could run at optimum efficiency rather than at a range of speeds. If you run out of fuel it's out with the footpump............................ Quote Link to comment Share on other sites More sharing options...
landroversforever Posted May 29, 2008 Share Posted May 29, 2008 I designed a multi-stage radial steam engine, intending to build a butane fired, closed loop steam bicycle - but never quite got round to it what a bonkers sounding design That has to be the quote of the year Quote Link to comment Share on other sites More sharing options...
simonr Posted May 29, 2008 Share Posted May 29, 2008 Now I'm home from the pub - that does sound quite funny! Si Quote Link to comment Share on other sites More sharing options...
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