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Diogenes

OSE is a long way from developing its car, and I doubt wikispeed will be delivering a low cost people's car any time soon. Possibly never. Already there has been interest in trying to emulate a unimog, a notoriously expensive but rugged vehicle. And on the youtube feed, a video interviewing someone from Mobius Motors was just uploaded. I hadn't heard of them, but they make a car for less than $6k, built for Africa.

Here's what I gather is the holy grail vehicle for transforming lives:

-Simple mechanics, no 'brain,' or need for complex diagnostic tools. Beginners can learn it with the help of documentation.
-Low cost of less than $6000, similar to Mobius. Semi-affordable for the poor and the developing world.
-High ground clearance, AWD, and skidplate, similar to Mobius or unimog. Appropriate for agricultural uses, rural uses, and degraded infrastructure uses.
-High horse power, similar to a unimog. Suitable for agricultural and business purposes.
-Modular components compatible with OSE's industrial tools, similar to Wikispeed. To slash down cost and supply chains.
-Can carry at least 4 adults or 2 adults and three children or two adults and cargo. Suitable as a passenger or cargo vehicle.
-Street legal and safe, similar to wikispeed. Allows it to fulfill its purpose as a passenger vehicle.
-Doors and a roof, rain proof. Suitable as a passenger vehicle in all climates.
-High mileage, and/or compatible with many fuels. Future proofed against rising fuel costs and diminishing fossil fuel supply.

So, what if we worked backwards? What if we started by picking an old production vehicle, and then added in OSE elements as they became available? For example, picking like a Type 2 VW Van and then adding in a power cube element, or a different OSE engine once it became available, or had documentation for creating a high ground clearance portal axles, making it AWD, mounting a skid plate, and things like that? Eventually everything could be phased out and replaced by OSE components. Note, I only picked a VW Van because of its simple mechanics, size (can be converted to a pickup, mass transit, or cargo vehicle), and that there's a lot of them. If the engine was to be replaced entirely, newer vehicles that don't run could be used. It should be a ubiquitous vehicle though, so that a large supply of ones that no longer run could be had for next to nothing. A vehicle with an engine in the front is probably better anyway, for aerodynamics.

If we were replacing everything but the frame and body, no one would even be able to tell that they had cheap OSE guts. And they'd be street legal and as safe as the parent model.

Diogenes

What's with the push for a steam engine power cube for vehicles? I assume this would be coupled to a wood gasifier. But I really think a gasifier should be a static application, producing electricity and denser hydrocarbon fuels like propane or diesel at home in conjunction with a solar concentrator and maybe a furnace to thermally decompose the wood. Home made sustainable fuel allows the range and power of diesel and gasoline vehicles without lugging around heavy equipment.

It would be incredibly cool if the truck could haul around a self-contained fuel trailer, though, I'll grant. Like, the ability to drive 300 miles or so, then stop and charge for a week or two, refilling its own fuel. If you're going to be pulling around a gasifier and steam generator anyway, you might as well put on your angular oversized shades and do the impossible. If something like that was made a reality, you'd essentially be liberating millions of people by giving them shelter, and limitless electricity, water, mobility, and opportunity.

Robotbeat

The beauty of the gasifier is the ability to modify an existing internal combustion engine to run on woodchips. I seriously doubt a steam engine will be superior to an internal combustion engine for this purpose. And, of course, you could run it with common gasoline or possibly methane. Electric cars aren't that difficult to build on the small scale especially if you use cheaper batteries. the drawback there of course is the fact that the batteries don't last very long. If there was an easy way to recondition old lead acid batteries again and again essentially forever then a do-it-yourself electric car might be the best choice for small commutes. In any case making the powertrain modular is a necessity. But I disagree with the requirements of high horsepower and all-wheel-drive because these run counter to a sustainable and low cost for operations vehicle.

Diogenes

What kind of suspension is desirable for the OSE vehicle? Can a rod and wire mill make coil springs? Leaf springs seem most easy to replicate on OSE equipment.

Robotbeat, appreciate the comment, why do you say AWD and high HP are not sustainable? For many conditions they are a necessity, like in Africa. You make a good point, though, for a commuter car role it should be able to switch down to a single power cube and 4x2 to avoid needless drains on fuel. But then again AWD are usually RWD until the extra traction is called for, so maybe just have a second power cube attachable by a quick attach plate for rapid upgrading to 'heavy duty' mode?

I actually figured out that the car is intended to be hydraulic powered. Which has significant implications. No driveshaft, no traditional transmission, and hydraulic power delivery to all four wheels is possible fairly cheaply by two hoses. Much higher torque power, less weight, higher efficiency, and runs easily on a powercube. I'm intrigued, although I still think a gasifier/steam generator/steam engine is a bridge too far.

Bastelmike

Diogenes wrote:

Much higher torque power, less weight, higher efficiency, and runs easily on a powercube.

Not really true!

- higher torque power: only if the hydraulic motors are oversized which adds to cost and weight and further reduces efficiency

- less weight: maybe, it depends

- higher efficiency: no, definitely not. Poorer in efficiency than mechanical transmission and poorer than electrical transmission like a diesel locomotive

Hydrostatic transmission is something for people who aren't capable of designing a mchanical drivetrain

Bastelmike

Diogenes

The US EPA claims that a series hydraulic hybrid is 50% - 100% more efficient than traditional automobiles. That's what I was basing the higher efficiency on. What are you talking about specifically as a more efficient alternative to a hydraulic system?

Are you in favor of not using powercubes at all? If powercubes are to be used it makes sense to have the vehicle hydraulically propelled, would it not?

Robotbeat

Interview go like the tractors that already needs hydraulic power then hydraulic power is not it all idiotic but is a wonderful design decision in my perspective. the progress so far in the tractor shows that it cuts down on Development time and costs significantly.

BoilermakerBen

I feel adding a hydraulic system is definitely a step ahead. It relieves the dependance on an age old system and the mentality linked with it. I'm sure it will open up more areas of innovation. There are many ways to pressurise fluids without the need for an internal combustion engine or even rotational motion. More immediately though, pressurised fluid seams to be a much more efficient way of energy storage and a hydraulic system would enable the use of it. I think the end goal in this respect would be powering a motion vehicle with a non motion energy origin.

Some other good features I could see with hydraulic setup.
-Optimising the energy output of an engine by having it run at a static and optimal RPM.
-Reduce amounts of moving parts in the car, less drivetrain.
-Consistent torque delivery because of static power levels (pressure).
-Reduced noise.

Nick

Ben,

How about a free piston steam engine for developing the hydraulic power? I blogged about the idea a while ago here at OSE http://blog.opensourceecology.org/2009/01/steam-dreams/ never really got much interest, though I still think its a solid idea worth investigating.

Matt_Maier

Yeah, hydraulics is probably the way to go with modularity being so important.

Diogenes

About modularity. Even if we can manage 100% more efficiency than standard vehicles, which is a pretty bold goal in itself, a power cube presently has 18 bhp. It's possible to make really heavy vehicles run on as little as 30 horse power, judging by mid 60s vehicles with simpler mechanics than today's, but I think the vehicle will need its own power cube design. The idea of it being plug and play is essential: modularity is very important for ease of design, but I'm not so sure that universal modularity is as important. Is it really a cardinal sin to have variants on the open source technology for specific vehicle designs? It doesn't look like an open source IC engine is even considered important to the GVCS, anyway. I don't really see that as being OSE's problem since the GVCS doesn't require it, but I think an earnest attempt at an OS Vehicle Kit will. I'm worried about the efficiency of having at least two engines for the vehicle.

Basically, my vision is a non running donor vehicle, with a power cube variant plugged into the engine bay, and an OS hydraulic hybrid powertrain installed for the base unit and prototype. Then upgraded to portal axles, a skidplate, and toggling AWD for the primary variant vehicle mission, then upgraded to a self sufficient (except food) motor home for a third vehicle mission. And eventually using OSE elements to phase out the body and frame with aluminum and carbon fibre, the suspension, the electrical system, the trailer, and all the rest of it.

That way, the prototype is developed for three vehicle missions on one single donor vehicle and one (more powerful and appropriate) powercube. Thus keeping costs down. A donor vehicle that doesn't run could be as little as $500, and a more powerful powercube could be only a bit more expensive. Maybe $2400 instead of $1600 (as of powercube 6).

Another thing I'm not sure about is the low PSI, of 3k. Then again, I don't have a doctorate in fluid dynamics. :P

Bastelmike

@Diogenes, Matt_Maier
Indeed, I am in favor of not using power cubes for car and truck. Does it make any sense to have a car with two or four power cubes installed. It increases maintenance costs, and the small powercube IC engines will be shorter lived than a large car engine or especially a truck diesel.
And with a truck, IMO it's ridiculous to use 5 - 10 powercubes. I doubt that anyone would buy such a truck.

Also its not useful to design a much larger power cube because you can't handle it without a crane.
Having a car wit powercubes is no advantage - noone is willing to change powercubes daily and most cars aren't out of use for longer periods.

@Diogenes, Robotbeat, BoilermakerBen

The efficiency I have been talking about is the efficiency of the power transmission, i.e. how much of the mechanical energy the motor produces is delivered to the wheels.

For mechanical drivetrains with a gearbox this efficiency is 90-92%, and this is constant for varying forces and speeds.

Hydraulic pumps and motors have efficiencies under optimum conditions of ~90% each. Thus combined efficiency is 81%. And the efficiency of pumps drops a lot if operated below maximum hydraulic flow. Similarly the efficiency of a motor drops if not operated with full torque. And cars are typically not operated under full load most of the time, so transmission efficiency in a car averages much below 80%. Thats the math with hydrostatic transmission

There's no reason to use hydraulics, mechanical or electrical is clearly superior.

Bastelmike

Diogenes

Well, the thing about hydraulics, it seems, is that you only need a lot of the power of an engine for acceleration, and you need much less engine once you're cruising. Hydraulics offers a way to accelerate quickly without a huge engine, by allowing one to store energy without batteries for acceleration and get regenerative braking in the deal to boot. So even if hydraulics is somewhat less efficient in power transmission (I'm not a specialist so I don't know about those details), it seems to make it up with interest in fuel savings, a smaller engine, fewer parts to fail or maintain, simpler mechanics (important for DIY systems and empowering the poor), and on and on.

Matt_Maier

@Diogenes

Marcin seems to be focused on an external combustion engine as the eventual in-house power source. I can see benefits to internal or external...or even electric motors. However, I think that producing and maintaining an engine is a step up in complexity. The tolerances in materials and fit/finish that an engine requires put them into a different level in terms of required infrastructure and expertise. Kind of like tires. Sure, you can kludge together something that looks like a tire if you have rubber and a way to work with it, but you're not going to get anything like the performance one would normally expect from even a cheap COTS tire. I think OSE needs to work its way up through lower levels of complexity. Eventually we'll get to things like scratch-built engines, but focusing on that now would just be a distraction.

@Diogenes

I can see your hypothetical progression there, but I can only see it working for a specific sub-section of vehicles. It would have to be a work-oriented vehicle in the first place, like a truck. At a minimum you'd need body-on-frame, a wide track and as much interior volume as possible. Gradually replacing all the subsystems would probably introduce more cost and complexity than necessary. If you have to tear the car apart to install a series-hydraulic system (engine, tubes, motors, etc) then you might as well do a bunch of other work while the vehicle is disassembled. If you phase it out you have to tear the vehicle apart several times and then put it all back together several times. Also, it seems like you'd only be preserving the subsystems that are the easiest to build from scratch in the first place. Why keep the frame and suspension when those are the things that are just simple hunks of metal that you could fabricate on your own anyway?

@Bastelmike

The existing power cube design is sized more-or-less appropriately for the tractor and maybe a couple other things, particularly stationary production machines like the CEB press. It's not appropriate for a vehicle that is supposed to either move at high speeds or carry heavy loads long distances. If for no other reason its power-to-weight ratio is pretty horrible. I think the concept is sound, tho. Eventually there will be a range of power cubes, with larger ones being the most obvious next step. The useful thing about hydraulics is that you can build the "transmission" right into the engine module because hydraulic pumps are actually pretty small. That way you can always move the power cube, even if it's heavy, because you can just run hydraulic lines from it to a crane and move it while it's running. You can't do that with a mechanical transmission. I don't think the efficiency gain is going to come from switching the power cube between vehicles every day. That will definitely be an option that will become efficient for operations that involve lots of single-use vehicles (like if you have a telehandler that sits around for weeks but is super useful every now and then). I think the efficiency gains will be realized through ease of procurement and maintenance. Standardization doesn't mean anything when you only have to do one thing. It is valuable when you have to do a lot of things. Obviously the average (first world) person can afford to buy a $10,000 power source that sits idle for 23 hours of the day; that's not a barrier so they won't get much benefit from the modularity feature. The benefits will accrue to the system as a whole and to a certain extent to the organizations that get a lot of work done.

@Bastelmike

The hydraulic system can be more efficient than a mechanical system if it is a hybrid with regenerative braking. The engine and the braking system will charge an accumulator that will take care of low-speed high-torque situations (most of what happens). A real-world test of package delivery trucks returned something like 80mpg. I think the EPA did it. You can google it and it should be on the wiki somewhere. The reason to use hydraulics is modularity and consolidation of the supply chain. All the functions of a vehicle, aside from the electrical necessities like a spark, can be provided by hydraulic power (torque, braking, suspension, etc). More importantly, by the same hydraulic components, or at least components that are largely identical. The same can't be said for mechanical systems.

BoilermakerBen

I have only done limited reading on the power cube, but isn't a power cube just an internal combustion engine hooked up to a hydraulic motor? I think it is supposed to be a modular and transportable power source to power all machinery on a farm. I'm going to assume that when power cube is mentioned here you are talking about putting an integrated engine-hydraulic system and not a big, bulky steel framed cube that can only be lifted by a machine.

@Bastelmike
Drive line efficiency is not linear and is mostly varied on engine power output. Sure the 2012 model tiny FWD hatch backs with their multi millions of dollars worth of R&D put into them may have a low 8% loss on average. But this is typically over 15% with most cars, more for RWD, AWD and multi diff trucks. I think more then 25% loss in some vehicles. As far as I know, drive line power loss is from friction, drag and inertia. All of these variables comes from moving parts, so by reducing the amount of moving parts, in thoery we are reducing power loss. Specially using fluid clutches and gearing. However I am definitely no expert in this field, so maybe fluid pump/motor do have more loss over a typical mechanical drive line.

There is also the effiecency of the engine itself, being at a static RPM. When storage tanks are full the engine is simply turned off. The erratic nature of car engines in itself is very inefficient. Engines could be developed for a static RPM with huge efficiency. I reckon you could get away with engines 20% the capacity of the ones today using a fluid system. But, I could be wrong xD

@Nick
A free piston system could work to pressurise a storage tank. I think it is the first compression method ever invented, but that doesn't mean it won't work. It would need research and development to see it is viable over other means. A steam engine on a vehicle I think is a bad idea mainly becaase of lack of space needed in order to fuel the steam engine. Steam engines should stay at a home in my opinion. The engine on this car could be power by syngas, biofuel or alcohol which can be produced at home (maybe including a steam engine). The storage tanks can be replenished at home also, using a power cube perhaps.

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