Talk:Car/Kinentic Vehicles Proposal - Revision history

ChuckH at 15:56, 28 February 2012

2012-02-28T15:56:00Z

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	From zero to 30 mph, the hydraulic motor is working at better than 90% efficiency, which is better than my current transmission-and-differential system. However, at full power at top speed, motor efficiency drops to 60%. What's worse is, high RPM efficiency drops further when power is reduced; cruising at 60 mph (80% of full RPM) my car currently requires about 8 hp (1/4 of maximum engine power) at the crank, but with this hydraulic motor at that RPM and torque, efficiency drops to 50%...and that's not including pumping losses through the valves and hoses, or the inefficiencies of the pump itself. In cruise, this hypothetical hydraulic drive system will be less than 50% efficient at converting engine rotation to wheel rotation. The complete system efficiency is even worse, because since in order to equal the performance of a 32 horse engine with mechanical transmission, the hydraulic system will need more horsepower, which means a bigger engine, which increases weight and lowers fuel efficiency.		From zero to 30 mph, the hydraulic motor is working at better than 90% efficiency, which is better than my current transmission-and-differential system. However, at full power at top speed, motor efficiency drops to 60%. What's worse is, high RPM efficiency drops further when power is reduced; cruising at 60 mph (80% of full RPM) my car currently requires about 8 hp (1/4 of maximum engine power) at the crank, but with this hydraulic motor at that RPM and torque, efficiency drops to 50%...and that's not including pumping losses through the valves and hoses, or the inefficiencies of the pump itself. In cruise, this hypothetical hydraulic drive system will be less than 50% efficient at converting engine rotation to wheel rotation. The complete system efficiency is even worse, because since in order to equal the performance of a 32 horse engine with mechanical transmission, the hydraulic system will need more horsepower, which means a bigger engine, which increases weight and lowers fuel efficiency.

	From the hypothetical to the documented, using the Power Cube BOM and the princehyd.com and briggsandstratton.com web sites, that pump and motor combo can give us 12.11 GPH and 3000 psi at 24.33 hp--but let's throttle down slightly to 12 gph at 24.11 because it makes the math easier. The Wolverine CMM50 georotor motor looks like a good choice for a drive motor; it's the right pressure flow and RPM range for the Power Cube and OS Car, if we use two of them in series we can have two wheel drive and won't need a differential...so cut the pressure in half ('cause there's two of them) and subtract 100 psi for back pressure and the drag of the rest of the hydraulic system valves, hoses and fittings (why 100 psi? Because I don't know exactly and deducting 100 psi makes the math so easy) and looking at the CMM50 efficiency chart on princehyd.com (Prince makes Wolverine) we find those motors can take in 12 GPM at 1400 PSI (each, in series) and put out 457 inch pounds of torque at 888 RPM, which is 6.44 horsepower each, total for two is 12.88 hp...24.11 hp in, 12.88 hp out = about 53% efficiency at full power. And since this car isn't going to need 12.88 wheel horsepower to cruise, hopefully it will need half that, which at those revs drops efficiency even further.		From the hypothetical to the documented, using the Power Cube BOM and the princehyd.com and briggsandstratton.com web sites, that pump and motor combo can give us 12.11 GPH and 3000 psi at 24.33 hp--but let's throttle down slightly to 12 gph at 24.11 because it makes the math easier. The Wolverine CMM50 georotor motor looks like a good choice for a drive motor; it's the right pressure flow and RPM range for the Power Cube and OS Car, if we use two of them in series we can have two wheel drive and won't need a differential...''(comment: actually plumbing two hydraulic motors in series simulates a solid axle: same number of revolutions on each shaft. You want to plumb them in parallel to act like a differential. [[User:ChuckH\|ChuckH]] 16:56, 28 February 2012 (CET))'' so cut the pressure in half ('cause there's two of them) and subtract 100 psi for back pressure and the drag of the rest of the hydraulic system valves, hoses and fittings (why 100 psi? Because I don't know exactly and deducting 100 psi makes the math so easy) and looking at the CMM50 efficiency chart on princehyd.com (Prince makes Wolverine) we find those motors can take in 12 GPM at 1400 PSI (each, in series) and put out 457 inch pounds of torque at 888 RPM, which is 6.44 horsepower each, total for two is 12.88 hp...24.11 hp in, 12.88 hp out = about 53% efficiency at full power. And since this car isn't going to need 12.88 wheel horsepower to cruise, hopefully it will need half that, which at those revs drops efficiency even further.

	In brief (hah! about time I did something brief) the Power Cube (or any fixed displacement hydraulic pump system) is a poor power source for a road car, because of its severe performance and fuel economy handicaps. [[JackMcCornack]] 2/23/12		In brief (hah! about time I did something brief) the Power Cube (or any fixed displacement hydraulic pump system) is a poor power source for a road car, because of its severe performance and fuel economy handicaps. [[JackMcCornack]] 2/23/12

ChuckH at 16:15, 27 February 2012

2012-02-27T16:15:49Z

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	In brief (hah! about time I did something brief) the Power Cube (or any fixed displacement hydraulic pump system) is a poor power source for a road car, because of its severe performance and fuel economy handicaps. [[JackMcCornack]] 2/23/12		In brief (hah! about time I did something brief) the Power Cube (or any fixed displacement hydraulic pump system) is a poor power source for a road car, because of its severe performance and fuel economy handicaps. [[JackMcCornack]] 2/23/12

			* My sense is that hydraulic drive doesn't change this basic truth of getting power from an IC engine to vehicle motion: you need a wider range of speed at the wheels than the engine can handle, so you need a transmission of some kind. Porportional hydraulic valves for speed control -- as used in [[Lifetrac]] -- have too much throttling loss for an efficient application. The most common approach is a variable displacement pump (or one pump per circuit, a.k.a. "displacement control" in hydraulic drive parlance). A fairly new approach is the [http://www.innas.com/IHT_CPR.html common pressure rail] system with a [[Stationary_Hydraulic_Power#Hydraulic_pressure_transformation \|flow rate transformer]] per circuit. IMHO it would be very good for the GVCS ecosystem in the long run to develop a simple switch-mode hydraulic transformer; however placing this on the critical path for first-prototype-car development may be too risky. [[User:ChuckH\|ChuckH]] 17:15, 27 February 2012 (CET)

	* I'm glad you can do the math on it (I can't). I totally agree that the Power Cube isn't suitable for a highway-capable passenger vehicle. For numerous reasons. It seems like a good idea to consider Wikispeed's solution, which is to physically position the engine so that it can directly drive a pair of wheels. If we want to go with the 2-passenger 3-wheel configuration we could just put their engine module in front and have one dragger wheel at the back. The only reason to go for a hydraulic drivetrain is if you want to deliver power to physically separate areas, which is nice to have but isn't necessary. - [[Matt_Maier]] 23FEB2012		* I'm glad you can do the math on it (I can't). I totally agree that the Power Cube isn't suitable for a highway-capable passenger vehicle. For numerous reasons. It seems like a good idea to consider Wikispeed's solution, which is to physically position the engine so that it can directly drive a pair of wheels. If we want to go with the 2-passenger 3-wheel configuration we could just put their engine module in front and have one dragger wheel at the back. The only reason to go for a hydraulic drivetrain is if you want to deliver power to physically separate areas, which is nice to have but isn't necessary. - [[Matt_Maier]] 23FEB2012

JackMcCornack: More musings re hydraulic hybrid systems, and a bit on why I favor four wheels

2012-02-26T00:50:41Z

More musings re hydraulic hybrid systems, and a bit on why I favor four wheels

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	From the hypothetical to the documented, using the Power Cube BOM and the princehyd.com and briggsandstratton.com web sites, that pump and motor combo can give us 12.11 GPH and 3000 psi at 24.33 hp--but let's throttle down slightly to 12 gph at 24.11 because it makes the math easier. The Wolverine CMM50 georotor motor looks like a good choice for a drive motor; it's the right pressure flow and RPM range for the Power Cube and OS Car, if we use two of them in series we can have two wheel drive and won't need a differential...so cut the pressure in half ('cause there's two of them) and subtract 100 psi for back pressure and the drag of the rest of the hydraulic system valves, hoses and fittings (why 100 psi? Because I don't know exactly and deducting 100 psi makes the math so easy) and looking at the CMM50 efficiency chart on princehyd.com (Prince makes Wolverine) we find those motors can take in 12 GPM at 1400 PSI (each, in series) and put out 457 inch pounds of torque at 888 RPM, which is 6.44 horsepower each, total for two is 12.88 hp...24.11 hp in, 12.88 hp out = about 53% efficiency at full power. And since this car isn't going to need 12.88 wheel horsepower to cruise, hopefully it will need half that, which at those revs drops efficiency even further.		From the hypothetical to the documented, using the Power Cube BOM and the princehyd.com and briggsandstratton.com web sites, that pump and motor combo can give us 12.11 GPH and 3000 psi at 24.33 hp--but let's throttle down slightly to 12 gph at 24.11 because it makes the math easier. The Wolverine CMM50 georotor motor looks like a good choice for a drive motor; it's the right pressure flow and RPM range for the Power Cube and OS Car, if we use two of them in series we can have two wheel drive and won't need a differential...so cut the pressure in half ('cause there's two of them) and subtract 100 psi for back pressure and the drag of the rest of the hydraulic system valves, hoses and fittings (why 100 psi? Because I don't know exactly and deducting 100 psi makes the math so easy) and looking at the CMM50 efficiency chart on princehyd.com (Prince makes Wolverine) we find those motors can take in 12 GPM at 1400 PSI (each, in series) and put out 457 inch pounds of torque at 888 RPM, which is 6.44 horsepower each, total for two is 12.88 hp...24.11 hp in, 12.88 hp out = about 53% efficiency at full power. And since this car isn't going to need 12.88 wheel horsepower to cruise, hopefully it will need half that, which at those revs drops efficiency even further.

	In brief (hah! about time I did something brief) the Power Cube (or any fixed displacement hydraulic pump system) is a poor power source for a road car, because of its severe performance and fuel economy handicaps. [[JackMcCornack]] 2/23/12		In brief (hah! about time I did something brief) the Power Cube (or any fixed displacement hydraulic pump system) is a poor power source for a road car, because of its severe performance and fuel economy handicaps. [[JackMcCornack]] 2/23/12

	* I'm glad you can do the math on it (I can't). I totally agree that the Power Cube isn't suitable for a highway-capable passenger vehicle. For numerous reasons. It seems like a good idea to consider Wikispeed's solution, which is to physically position the engine so that it can directly drive a pair of wheels. If we want to go with the 2-passenger 3-wheel configuration we could just put their engine module in front and have one dragger wheel at the back. The only reason to go for a hydraulic drivetrain is if you want to deliver power to physically separate areas, which is nice to have but isn't necessary. - [[Matt_Maier]] 23FEB2012		* I'm glad you can do the math on it (I can't). I totally agree that the Power Cube isn't suitable for a highway-capable passenger vehicle. For numerous reasons. It seems like a good idea to consider Wikispeed's solution, which is to physically position the engine so that it can directly drive a pair of wheels. If we want to go with the 2-passenger 3-wheel configuration we could just put their engine module in front and have one dragger wheel at the back. The only reason to go for a hydraulic drivetrain is if you want to deliver power to physically separate areas, which is nice to have but isn't necessary. - [[Matt_Maier]] 23FEB2012


			There are other reasons for a hydraulic drive train. With more sophisticated pumps and motors, the efficiency losses might compare well with the efficiency losses of a transmission/differential drive system, and hydraulic drive could be lighter than the mechanical drive, and it brings forth the possibility of energy storage for acceleration and braking (hydraulic regenerative braking) as described on the Hybrid_Hydraulic_System wiki page (which Matt_Maier has been keeping current). I've been doing math and research for the last couple of days, coming to a conclusion (there's not much time left for me) on the best layout for this prototype car, and I've decided four wheels is better than three...and the future hydraulic hybrid is part of why. The Power Cube itself is another reason, and though I dont think the PC is ready for a car in its current state, I think it has great potential. Besides, Marcin likes the power cube, and he's smarter than me by scads.

			I posted my full length 3 vs. 4 essay on the Car/Design_Criteria discussion page, at http://opensourceecology.org/wiki/Talk:Car/Design_Criteria
			[[JackMcCornack]] 2/25/12

Matt Maier at 05:00, 24 February 2012

2012-02-24T05:00:02Z

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	In brief (hah! about time I did something brief) the Power Cube (or any fixed displacement hydraulic pump system) is a poor power source for a road car, because of its severe performance and fuel economy handicaps. [[JackMcCornack]] 2/23/12		In brief (hah! about time I did something brief) the Power Cube (or any fixed displacement hydraulic pump system) is a poor power source for a road car, because of its severe performance and fuel economy handicaps. [[JackMcCornack]] 2/23/12

	* I'm glad you can do the math on it (I can't). I totally agree that the Power Cube isn't suitable for a highway-capable passenger vehicle. For numerous reasons. It seems like a good idea to consider Wikispeed's solution, which is to physically position the engine so that it can directly drive a pair of wheels. If we want to go with the 2-passenger 3-wheel configuration we could just put their engine module in front and have one dragger wheel at the back. The only reason to go for a hydraulic drivetrain is if you want to deliver power to physically separate areas, which is nice to have but isn't necessary.		* I'm glad you can do the math on it (I can't). I totally agree that the Power Cube isn't suitable for a highway-capable passenger vehicle. For numerous reasons. It seems like a good idea to consider Wikispeed's solution, which is to physically position the engine so that it can directly drive a pair of wheels. If we want to go with the 2-passenger 3-wheel configuration we could just put their engine module in front and have one dragger wheel at the back. The only reason to go for a hydraulic drivetrain is if you want to deliver power to physically separate areas, which is nice to have but isn't necessary. - [[Matt_Maier]] 23FEB2012

Matt Maier at 00:17, 24 February 2012

2012-02-24T00:17:41Z

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	In brief (hah! about time I did something brief) the Power Cube (or any fixed displacement hydraulic pump system) is a poor power source for a road car, because of its severe performance and fuel economy handicaps. [[JackMcCornack]] 2/23/12		In brief (hah! about time I did something brief) the Power Cube (or any fixed displacement hydraulic pump system) is a poor power source for a road car, because of its severe performance and fuel economy handicaps. [[JackMcCornack]] 2/23/12

			* I'm glad you can do the math on it (I can't). I totally agree that the Power Cube isn't suitable for a highway-capable passenger vehicle. For numerous reasons. It seems like a good idea to consider Wikispeed's solution, which is to physically position the engine so that it can directly drive a pair of wheels. If we want to go with the 2-passenger 3-wheel configuration we could just put their engine module in front and have one dragger wheel at the back. The only reason to go for a hydraulic drivetrain is if you want to deliver power to physically separate areas, which is nice to have but isn't necessary.

JackMcCornack: added a discourse on hydraulic drive issues for road cars.

2012-02-23T21:22:22Z

added a discourse on hydraulic drive issues for road cars.

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	* One of the reasons active hydraulic suspensions weren't popular in car racing was the danger of getting sprayed by 3000psi hot oil. At that pressure it gets injected straight into your body; right through the skin. Kind of dangerous.		* One of the reasons active hydraulic suspensions weren't popular in car racing was the danger of getting sprayed by 3000psi hot oil. At that pressure it gets injected straight into your body; right through the skin. Kind of dangerous.
	* I figured the power cube(s) would go in between the front wheels, the passengers behind them, and then a single rear wheel. The ones we have now are kind of bulky, tho. A 2 foot cube is hard to fit anywhere. But that's probably okay; I figure we'll need a new power cube model for a passenger vehicle anyway. Getting up to 70mph will probably require a redesign for significantly higher flow if not for additional reasons. - [[Matt_Maier]]		* I figured the power cube(s) would go in between the front wheels, the passengers behind them, and then a single rear wheel. The ones we have now are kind of bulky, tho. A 2 foot cube is hard to fit anywhere. But that's probably okay; I figure we'll need a new power cube model for a passenger vehicle anyway. Getting up to 70mph will probably require a redesign for significantly higher flow if not for additional reasons. - [[Matt_Maier]]


			Thanks for the links, Matt, and the insight...I followed the links you gave and got some examples.

			* Technically anything can be "low speed high force" if you gear them properly :-)

			True, but with a gear pump a la the Prince SP20B16 used in the Power Cube, you only get one gear, and in most machinery (including mobile agricultural machinery) you gear that gear to be 'low'. If you gear it for high speed (highway speed rather than furrow speed) then force goes down accordingly. One -could- make a car work with hydraulic drive and a gear pump, but it would be like driving a car with only one gear and a hydraulic clutch: if you geared it low you'd still be able to go fast (if you had the horsepower) but you'd be spinning the motor way outside its efficient RPM range, if you geared it high for high efficiency cruising, you'd need huge gobs of engine torque to get away from stop signs, because low RPM power recovery would be so inefficient.
			There's an "Overall efficiency" pressure/rpm/efficiency graph on page 9 of the <steerable hydraulic wheel motor> pdf link on the [[Hybrid_Hydraulic_System]] page; it's percentages are quite typical of fixed displacement hydraulic motor graphs, regardless of size. This graph assumes a variable displacement pump (it's a wheel motor for big equipment) so it assumes the pump will deliver variable pressure at variable gallons per minute (high pressure at low revs) but it's valid for fixed displacement pumps (such as the Power Cube) too, if you cut the pressure off at the max pressure at max RPM. So, draw a horizontal line across the graph at 2000 psi and let's gear it in a car so 100% RPM is 75 mph, and let's power the pump with the engine in my own high mileage car (32 hp diesel).

			From zero to 30 mph, the hydraulic motor is working at better than 90% efficiency, which is better than my current transmission-and-differential system. However, at full power at top speed, motor efficiency drops to 60%. What's worse is, high RPM efficiency drops further when power is reduced; cruising at 60 mph (80% of full RPM) my car currently requires about 8 hp (1/4 of maximum engine power) at the crank, but with this hydraulic motor at that RPM and torque, efficiency drops to 50%...and that's not including pumping losses through the valves and hoses, or the inefficiencies of the pump itself. In cruise, this hypothetical hydraulic drive system will be less than 50% efficient at converting engine rotation to wheel rotation. The complete system efficiency is even worse, because since in order to equal the performance of a 32 horse engine with mechanical transmission, the hydraulic system will need more horsepower, which means a bigger engine, which increases weight and lowers fuel efficiency.

			From the hypothetical to the documented, using the Power Cube BOM and the princehyd.com and briggsandstratton.com web sites, that pump and motor combo can give us 12.11 GPH and 3000 psi at 24.33 hp--but let's throttle down slightly to 12 gph at 24.11 because it makes the math easier. The Wolverine CMM50 georotor motor looks like a good choice for a drive motor; it's the right pressure flow and RPM range for the Power Cube and OS Car, if we use two of them in series we can have two wheel drive and won't need a differential...so cut the pressure in half ('cause there's two of them) and subtract 100 psi for back pressure and the drag of the rest of the hydraulic system valves, hoses and fittings (why 100 psi? Because I don't know exactly and deducting 100 psi makes the math so easy) and looking at the CMM50 efficiency chart on princehyd.com (Prince makes Wolverine) we find those motors can take in 12 GPM at 1400 PSI (each, in series) and put out 457 inch pounds of torque at 888 RPM, which is 6.44 horsepower each, total for two is 12.88 hp...24.11 hp in, 12.88 hp out = about 53% efficiency at full power. And since this car isn't going to need 12.88 wheel horsepower to cruise, hopefully it will need half that, which at those revs drops efficiency even further.

			In brief (hah! about time I did something brief) the Power Cube (or any fixed displacement hydraulic pump system) is a poor power source for a road car, because of its severe performance and fuel economy handicaps. [[JackMcCornack]] 2/23/12

Matt Maier at 23:12, 18 February 2012

2012-02-18T23:12:13Z

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	* Technically anything can be "low speed high force" if you gear them properly :-)		* Technically anything can be "low speed high force" if you gear them properly :-)
	* I've been collecting research on hybrid hydraulics for a while now. [[Hybrid_Hydraulic_System]] [[Research_Development#Design]]		* I've been collecting research on hybrid hydraulics for a while now. [[Hybrid_Hydraulic_System]] [[Car/Research_Development#Design]]
	* My mistake. It was a UPS truck. [http://www.epa.gov/otaq/technology/research/demonstration-vehicles.htm EPA Hybrid Hydraulic Program] [http://www.nfpa.com/Events/PDF/110323_Future_of_HHVs-IFPE_keynote_5.pdf presentation on HHV's]		* My mistake. It was a UPS truck. [http://www.epa.gov/otaq/technology/research/demonstration-vehicles.htm EPA Hybrid Hydraulic Program] [http://www.nfpa.com/Events/PDF/110323_Future_of_HHVs-IFPE_keynote_5.pdf presentation on HHV's]
	* One of the reasons active hydraulic suspensions weren't popular in car racing was the danger of getting sprayed by 3000psi hot oil. At that pressure it gets injected straight into your body; right through the skin. Kind of dangerous.		* One of the reasons active hydraulic suspensions weren't popular in car racing was the danger of getting sprayed by 3000psi hot oil. At that pressure it gets injected straight into your body; right through the skin. Kind of dangerous.
	* I figured the power cube(s) would go in between the front wheels, the passengers behind them, and then a single rear wheel. The ones we have now are kind of bulky, tho. A 2 foot cube is hard to fit anywhere. But that's probably okay; I figure we'll need a new power cube model for a passenger vehicle anyway. Getting up to 70mph will probably require a redesign for significantly higher flow if not for additional reasons. - [[Matt_Maier]]		* I figured the power cube(s) would go in between the front wheels, the passengers behind them, and then a single rear wheel. The ones we have now are kind of bulky, tho. A 2 foot cube is hard to fit anywhere. But that's probably okay; I figure we'll need a new power cube model for a passenger vehicle anyway. Getting up to 70mph will probably require a redesign for significantly higher flow if not for additional reasons. - [[Matt_Maier]]

Matt Maier at 23:11, 18 February 2012

2012-02-18T23:11:26Z

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	For example, can someone provide a drawing of where the Power Cube goes in a streamlined two passenger three wheeled car? All my sketches end up either unstable in roll, or with worse aerodynamic drag than four wheeled variants. - [[JackMcCornack]] 18FEB2012		For example, can someone provide a drawing of where the Power Cube goes in a streamlined two passenger three wheeled car? All my sketches end up either unstable in roll, or with worse aerodynamic drag than four wheeled variants. - [[JackMcCornack]] 18FEB2012

	Technically anything can be "low speed high force" if you gear them properly :-)
			* Technically anything can be "low speed high force" if you gear them properly :-)
	* I've been collecting research on hybrid hydraulics for a while now. [[Hybrid_Hydraulic_System]] [[Research_Development#Design]]		* I've been collecting research on hybrid hydraulics for a while now. [[Hybrid_Hydraulic_System]] [[Research_Development#Design]]
	* My mistake. It was a UPS truck. [http://www.epa.gov/otaq/technology/research/demonstration-vehicles.htm EPA Hybrid Hydraulic Program] [http://www.nfpa.com/Events/PDF/110323_Future_of_HHVs-IFPE_keynote_5.pdf presentation on HHV's]		* My mistake. It was a UPS truck. [http://www.epa.gov/otaq/technology/research/demonstration-vehicles.htm EPA Hybrid Hydraulic Program] [http://www.nfpa.com/Events/PDF/110323_Future_of_HHVs-IFPE_keynote_5.pdf presentation on HHV's]
	* One of the reasons active hydraulic suspensions weren't popular in car racing was the danger of getting sprayed by 3000psi hot oil. At that pressure it gets injected straight into your body; right through the skin. Kind of dangerous.		* One of the reasons active hydraulic suspensions weren't popular in car racing was the danger of getting sprayed by 3000psi hot oil. At that pressure it gets injected straight into your body; right through the skin. Kind of dangerous.
	* I figured the power cube(s) would go in between the front wheels, the passengers behind them, and then a single rear wheel. The ones we have now are kind of bulky, tho. A 2 foot cube is hard to fit anywhere. But that's probably okay; I figure we'll need a new power cube model for a passenger vehicle anyway. Getting up to 70mph will probably require a redesign for significantly higher flow if not for additional reasons.		* I figured the power cube(s) would go in between the front wheels, the passengers behind them, and then a single rear wheel. The ones we have now are kind of bulky, tho. A 2 foot cube is hard to fit anywhere. But that's probably okay; I figure we'll need a new power cube model for a passenger vehicle anyway. Getting up to 70mph will probably require a redesign for significantly higher flow if not for additional reasons. - [[Matt_Maier]]

Matt Maier at 23:11, 18 February 2012

2012-02-18T23:11:03Z

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	I'll try to find a place to list the trade-offs we need to consider before we start turning wrenches.		I'll try to find a place to list the trade-offs we need to consider before we start turning wrenches.
	For example, can someone provide a drawing of where the Power Cube goes in a streamlined two passenger three wheeled car? All my sketches end up either unstable in roll, or with worse aerodynamic drag than four wheeled variants. - [[JackMcCornack]] 18FEB2012		For example, can someone provide a drawing of where the Power Cube goes in a streamlined two passenger three wheeled car? All my sketches end up either unstable in roll, or with worse aerodynamic drag than four wheeled variants. - [[JackMcCornack]] 18FEB2012

			Technically anything can be "low speed high force" if you gear them properly :-)
			* I've been collecting research on hybrid hydraulics for a while now. [[Hybrid_Hydraulic_System]] [[Research_Development#Design]]
			* My mistake. It was a UPS truck. [http://www.epa.gov/otaq/technology/research/demonstration-vehicles.htm EPA Hybrid Hydraulic Program] [http://www.nfpa.com/Events/PDF/110323_Future_of_HHVs-IFPE_keynote_5.pdf presentation on HHV's]
			* One of the reasons active hydraulic suspensions weren't popular in car racing was the danger of getting sprayed by 3000psi hot oil. At that pressure it gets injected straight into your body; right through the skin. Kind of dangerous.
			* I figured the power cube(s) would go in between the front wheels, the passengers behind them, and then a single rear wheel. The ones we have now are kind of bulky, tho. A 2 foot cube is hard to fit anywhere. But that's probably okay; I figure we'll need a new power cube model for a passenger vehicle anyway. Getting up to 70mph will probably require a redesign for significantly higher flow if not for additional reasons.

JackMcCornack: Added a sig to previous response

2012-02-18T21:09:27Z

Added a sig to previous response

← Older revision		Revision as of 21:09, 18 February 2012
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	*All in all, the weight given to the other important (indeed more important) factors of the design will determine where efficiency factors rank, but there's a point when efficiency factors get low enough that there's no use bothering with the OS Car at all.		*All in all, the weight given to the other important (indeed more important) factors of the design will determine where efficiency factors rank, but there's a point when efficiency factors get low enough that there's no use bothering with the OS Car at all.
	I'll try to find a place to list the trade-offs we need to consider before we start turning wrenches.		I'll try to find a place to list the trade-offs we need to consider before we start turning wrenches.
	For example, can someone provide a drawing of where the Power Cube goes in a streamlined two passenger three wheeled car? All my sketches end up either unstable in roll, or with worse aerodynamic drag than four wheeled variants.		For example, can someone provide a drawing of where the Power Cube goes in a streamlined two passenger three wheeled car? All my sketches end up either unstable in roll, or with worse aerodynamic drag than four wheeled variants. - [[JackMcCornack]] 18FEB2012