hydrogen's second coming on the road?
Jerry Schneider
- Jerry Schneider -
Innovative Transportation Technologies
http://faculty.washington.edu/jbs/itrans
Jerry Roane
Here is what happens when the hydrogen tank is intentionally lit. This
image looks like the Hindenburg to me. If the imposed leak is closer to
the cabin it would look just like the Hindenburg. When cars wreck the
initial configuration is not maintained nor are the wheels always
pointed down. If I hear that Hindenburg history rewrite one more time I
may toss my lunch.
Jerry Roane
Bruce A. McHenry
o. 617 5007005
m. 202 460 1492
Walter Brewer
Bruce A. McHenry
Bruce
Bruce,Remember Quarterback Joe Naymath,(sp), has a Journalism degree!Walt Brewer
----- Original Message -----From: Bruce A. McHenrySent: Monday, April 30, 2007 9:18 PMSubject: [t-i] Re: hydrogen's second coming on the road?
I tried to write to the author to complain about this piece but emails sent to don.sherman and donald.sherman (@nyt.com ) bounced. The email follows:
Don,Shame on you! You perpetuate the hydrogen myth by reviewing vehicles but fail to probe the chemistry of hydrogen production. Would you please instead ask questions like: What are the ways to make hydrogen? What are the optimal efficiencies given the governing thermodynamics? What efficiencies are likely to be obtained? What does this mean for the price point of H2 vs other fuels or uses of the electricity? If you were to examine these questions instead of doing yet another puff piece about H2 vehicles funded in large part by federal grants, you would actually be doing readers a service instead of positioning eye candy for the auto makers and legislative proponents with only the most rudimentary appreciation of chemistry.Sincerely,Bruce McHenry
On 4/30/07, Jerry Schneider <j...@peak.org > wrote:
http://www.nytimes.com/2007/04/29/automobiles/29INTRO.html
- Jerry Schneider -
Innovative Transportation Technologies
http://faculty.washington.edu/jbs/itrans
o. 617 5007005
m. 202 460 1492
--
www.discussIT.org
a.boender
http://video.google.com/videoplay?docid=-481439206989688493&q=who+killed+the+electric+car+duration%3Along
This article in the NYT fits perfectly in the picture of the subtle play. They distract attention by luring people and especially journalists into
a future far away that allows fossil fuels to continue to be used without change.
Walter Brewer
Jerry Schneider
request to st...@nytimes.com or dire...@nytimes.com or you can send
a message to the Public Editor asking that it be forwarded to a particular
reporter.
http://www.nytimes.com/top/opinion/thepubliceditor/index.html
Ian Ford
wind, and plant sources. Since solar and wind don't produce a
transportable fuel, and since they are intermittent, a massively
decentralized energy storage medium is needed. I think the idea of
hydrogen fulfilling that role is still valid, and it may one day be the
least expensive medium.
Although there is hype and distortion, don't forget the original ideas
are still valid. Science News recently reported an advance in lower cost
fuel cell membranes; if/when there are complementary advances in
conversion efficiency and storage, the whole idea of vehicles running on
hydrogen will become very reasonable from a cost standpoint. On the
other hand, advances in battery cost, weight, recharge speeds and
lifetimes will ALSO fulfill the same need, so it seems that either one
could replace fossil fuels for vehicles.
a.boender wrote:
> I believe the hydrogen hype was created to kill the electric car.
> http://video.google.com/videoplay?docid=-481439206989688493&q=who+killed+the+electric+car+duration%3Along
> This article in the NYT fits perfectly in the picture of the subtle
> play. They distract attention by luring people and especially
> journalists into
> a future far away that allows fossil fuels to continue to be used
> without change.
--
Ian Ford i...@ianford.com 505.246.8490
Axisbase: 100% .NET database server and application development tool
Download free from www.ianford.com
Jerry Roane
You bring up an excellent topic about energy mix. It would make the most sense to use fossil fuels to bridge the lulls in renewable energy. This of course would require planning and that we not burn every molecule of fossil fuels before we convert. Rather than use elaborate processes to store energy for the lulls it would make the most sense to preserve fossil fuels for this purpose. We will not instantly run out of oil because when God put it down there he made it increasingly harder to get it out. This will naturally taper down production easing the transition to the next solution. Running out of easy access oil is probably the best thing that could happen to us. I predict that the hard to extract oil will be the gap filler for renewables. I do not believe that farm grown fuel will work out in a free market. It could exist in a distorted economic model like we have now. As time goes on processes will advance so it is premature to predict the winner in two decades but the starting point for crops is a 1% energy conversion to liquid fuel from real-time sunlight. Solar panels at 40.9% conversion efficiency will have a lead especially if you consider the cost of the real estate and lost food production. Both these numbers should rise as they are worked on so the 1% may go to 5% and the 40.9% may go to 80%. Crops just have a long way to go. I include crops grown in water pools too in my assessment. Enzymes are a crop just smaller and more of them.
One good point is the wind is much more constant than you may be aware. This is wind at 100 feet plus elevation not surface wind. Also solar panels compliment wind in their cycles. Hydrogen will need many times improvement to be a reversible energy storage solution. They need to give up on the gold plated platinum plates as a non-starter. I have heard rumors of no platinum solutions that sound plausible. Time will tell. The Automotive X Prize threw out hydrogen in their rules because the panel decided it was too far out in the future when cost was considered with performance.
Jerry Roane
a.boender
The rare fuel cells in laptop's and cell phones are DMFC's running on methanol
Hydrogen is the opposit of an energy carrier.
You cannot store it
You cannot transport it.
So Shell wants to produce it at the gas station.
The whole thing makes no sense, maybe Shell profits from it but I suspect that it will be only indirectly or by way of government subsidies.
A fuel cell does make sense.
I like the zinc-air fuell cell.
I like the story of the methanol economy best of all
Has any of you read George Olah's book on the subject?
Guala Luca
cheers
Luca Guala
-----Messaggio originale-----
Da: transport-...@googlegroups.com per conto di a.boender
Inviato: gio 03/05/2007 20.57
A: transport-...@googlegroups.com
Cc:
Oggetto: [t-i] Re: hydrogen's second coming on the road?
Jerry Roane
The internal combustion engine in practice is extremely inefficient. It is even more inefficient the way traditional geared transmissions have utilized it. Attached is where the energy goes in a traditional car. This is from the oil and gas industry not me. It is easy to confirm this information. Simply put your palm on the radiator cap of your car after driving for a while and you will feel where the bulk of the energy is leaking. You can see from this graph that the thermal efficiency of the engine is poor. There are those on this list enamored with the gains that can be made by upping the compression ratio and feeding the internal combustion engine diesel oil instead of gasoline but the upper limit on that is a 50% efficiency converting diesel 139,000 BTU/USgallon to rotation of the crank shaft. To add to the misery internal combustion engines are rated on a dyno at laboratory conditions at full throttle and the load is applied to slow the engine to the different RPMs via the dyno loading. This paints a much more rosy picture of the engine's true performance. In reality engines are sized based on how the car feels as it accelerates. Thus the marketing phase "fun to drive". That puts a 300 hp engine in a car that needs 22 hp to maintain speed on the highway. What that oversizing of the engine does is the engines are now running barely off the idle circuit. If you measure the distance your foot is from the floorboard on the accelerator pedal with a ruler you will see that as you drive you rarely push the throttle down more than a few millimeters. This causes the vacuum in the intake manifold to be very high (as in low pressure) which is overkill for trying to atomize the liquid droplets and get them to combine with the air to make the explosive mixture. This over pumping of the vacuum is just wasted effort and wasted energy. This is just one part of the inefficiency of an engine at a low percentage throttle opening. What is totally counter intuitive is liquid fueled engines are most efficient at fully open throttle. This is the most overlooked phenomenon in the automotive press. The magic of the Prius is they pick a smaller gas engine that has to run closer to full throttle when the computer asks for more power. They can do this because the electric motor and battery pack tucked under the seat backs of the fold down rear seats provides the acceleration instantaneous power on takeoff. In the TriTrack we use a linear motor for this function and because this high-dollar motor is shared by all who use that guideway the high cost of this performance is spread thin and is only pennies rather than have millions of people buy 300 hp engines like now. The other information that is totally passed over in the press is the continuously variable transmission. I worked on the Daryl Hillman CVT in 1979 and it achieved a 98% efficiency with a 4:1 to 1:1 continuous range. This was my first engineering job right out of college. As you can see from this chart the slush filled hydraulic transmission or grease filled manual transmission wastes much more than 2% of the energy. Even the rear end differential wastes more energy than you would ever imagine. The rear end gears are throwing very thick grease around in that closed chamber wasting energy like it just came gushing out of the ground. (which it used to do) With a three wheeled car there is no place to add a differential and waste that energy. As a simple illustration of how much energy a differential wastes read the mileage rating of a pickup truck and then compare that to the four wheel drive version of the same vehicle. The only difference is the added dead weight of yet another rear end and the energy waste that the gears rubbing and grease tossing does.
Fuel cells are not all that efficient but once electricity is generated or moved to the vehicle it is very efficient in getting rotation where you want it when you want it and throttling electric motors is VERY efficient. The fact that the car is now an electric car is why fuel cells come out looking good. I contend you can get electric power to the car with lower cost solutions like ordinary rechargeable batteries but that is another discussion. If the cost of the raw materials of fuel cells could be drastically reduced then they would work fine for making cars electric.
The advantage methane or propane has for a feed stock for fuel cells is those fuels can be delivered easily with what we have. The elephant in the room is the purity of the gas has to be extreme for the fuel cell to last any time at all. In the real world nothing is that pure so even if they solve the gold plated platinum plate cost problem they still have to deal with the purity issue. If they try to use natural gas as a feedstock they will need to put a lot of energy into getting the purity high enough as natural gas is "natural" and it is not even close to being a pure single gas but is a combination of hundreds of gaseous things that have to be refined and filtered. This is where we get helium for our balloons as one stray impurity in natural gas. The problem with using non-hydrogen as the feed stock is the extra stuff has to be blown into the atmosphere. Lots of carbon atoms and oxygen atoms in various combinations with other impurities. Not a pretty picture. Fine for a lighter sized fuel cell for a cell phone that gets tossed every other year but not a good choice for a high power device sized to move an iron based SUV.
As for developing an entirely new technology electric cars have been around as long as ICE. GM has made electric cars continuously since the beginning. You don't hear about these cars but GM has made them all along. The electric portion of the car is a done-deal it is the black box that delivers electricity on board the vehicle that has to be developed. The TriTrack strips out this portion and divides up the trip into its sections. For launch and catch we use a large expensive ground based linear motor that it hardwired with physically large copper wires to the city power grid. This 230 hp motor is the largest power requirement and so the delivery of this energy is via a moving magnetic field that is pushing a paddle under the car's belly. The street motor drops off when the car comes off the street so it is sized and powered for the street section of the journey. This 10 hp motor with intentionally heavy lead based batteries (been around for over 100 years and stable technology) powers the safe speed travel to the door of your trip. On the middle of the guideway section there is a higher-tech battery and/or fuel cell that will power the car at constant speed at about 81.5 hp. The duration of this supplied energy is between .7 minutes and 5.3 minutes for most cities. This extremely short energy delivery parameter allows the fuel cell storage to be very small. So small in fact that an ordinary battery can do the same job with no trouble. In this application the fuel cell would need to be so cheap that children's toys at Christmas would be using fuel cells instead of Energizers. I don't see that happening so the chances of a fuel cell powering the TriTrack in the middle section of guideway is slim and none for the next few years. I am open to the advent of improved fuel cells but we are not married to the idea like some large corporations and governments seem to be.
Sorry for the long version but you asked a fundamental question about why the ICE should be taken out back and shot. As an extreme fall back position we could always drop a 2 stroke snowmobile engine in the TriTrack and skip all the high flutin' electronic control but safety would suffer and the air pollution would be worse. 100% electric is superior on all measures.
Jerry Roane
Jerry Schneider
>The Ballard fuel cell used in the mercedes is fueled by methanol.
>The rare fuel cells in laptop's and cell phones are DMFC's running on methanol
>Hydrogen is the opposit of an energy carrier.
>You cannot store it
Yes, you can.
>You cannot transport it.
Yes, you can.
a.boender
Natural gas is the most common source together with coal presently to fabricate hydrogen.
Methanol is not natural and is easier to fabricate than hydrogen or ethanol and the most common source to fabricate methanol is natural gas.
There are many alternative sources. The best alternative source is CO2.
Methanol is toxic, but it is to be found in every household and causes rarely any accidents.
Guala Luca
first of all, thank you for the image you sent, I will use it in my presentations since it's a lot better than the one I use now!
You say an ICE can reach 50% efficiency. I would stop that at around 35-40% according to my information. And this is for almost-stationary engines like cargo ships, certainly not for land vehicles. When engineers pre-dimension the ancillary systems of an ICE for a land vehicle, the first rough calculation is that as much energy as goes into useful work will have to be dissipated by the cooling system, and another as much will exit right out of the exhaust as heat and kinetic energy of the exhaust gases.
By the way, the original post mentioned methanol as a fuel, not methane: you discuss using methane or propane to power a fuel cell. As far as I know, at the moment methane is not used directly in fuel cells, but it is used to extract H2 (producing CO2 in the process). Then H2 is used to feed the fuel cells. Alternatively, there are fuel cells that can use methanol directly as a fuel.
I have some idea of the low efficiency of the ICE from my studies and work, but I am aware that also the fuel cells are no big deal. Do they reach 50% efficiency in real life use? Hardly. This is the reason of my question. The "entirely new technology" I refer to is not the electric motor, I know that that has been around for a long time: I was refering to the fuel cell and its management system. Do we really need to develop this technology if its aim is to use methanol as a fuel? Methanol used in a fuel cell produces exhaust gases which pollute roughly as much as if the same stuff is burnt in an ICE. Unfortunately methanol, which is a liquid at ordinary temperature and pressure, is a VERY toxic substance hence my question about its use.
You mention a number of features about ICE that made me wonder a bit: grease filled manual tranmission, torque converter, rear axle differential, 300+Hp engines and vacuum to vaporize fuel droplets. This all refers to technology of the last Century! I refuse to believe that the average US car does not employ electronic ignition, front wheel drive and a proper mechanical gearbox in oil bath. I haven't seen grease filled gearboxes since I quit restoring pre-WW2 bikes!
As for needing 300+Hp to pwer a car, that's a marketing problem. European cars do very well with less than 100 Hp, although car makers are doing their best to convince the customer that more power and more weight and bulk is needed every year. This trend will reappear in electric cars too, just give the marketing people some time to sharpen their new knives.
As for the use of throttle to parzialize the power of an engine: that's a problem that entirely accrues to spark ignition ICE. Diesels don't need a throttle valve. The Prius engine goes around the problem by blowing out some intake air before injecting the fuel, thus allowing to use larger intake ducts (less pumping losses) and a higher compression ratio. In some way, it is a bit like the dreaded snowmobile engine you mention, which begins compression only when the ports are closed by the piston. The trouble of the 2 stroke engine is that nobody at my knowledge has yet come out with a reliable device to inject fuel after the ports are closed. The most promising design was the Australian Orbit, but it has fallen into some very deep drawer from which it has not been taken out again.
the dyno power curves are usually taken at different values of throttle openings (or injection pump delivery if Diesel) to get what is known as the "hill diagram". The best efficiency of an ICE is usually obtained not at full throttle, but at around 75-80%, and very near the max torque RPM. Then the customer only gets to know the boundary of this diagram, that is, the curve that describes the full throttle performance at various REVs values. The rest of the diagram is blanked out for some reason.
As for a three-wheeled vehicle not needing a differential (sorry if I am replying to your notes in sparse order) that, of course, has nothing to do with the fact that the vehicle is powered by an ICE or whatever else. The Morgan three wheelers of the 30's and 40's had no differential, nor did the Iso-BMW Isetta micro car of the 50's. Rather I would point out the fact that an electric motor can be placed directly into the wheel and a very efficient electronic control can take the place of the differential by powering separately the motors in each wheel of a vehicle with as many wheels as you please to put in it.
cheers, Luca
Michael Weidler
Jack Slade
a.boender
CH4 is natural gas and CH3OH is methanol.
Guala Luca
You capture CO2 (how? what energy efficiency?), then you add H2 which you obtain from electrolysis of water (theoretical energy efficiency 66%; true efficiency about 50-55%) to obtain CH3OH (what energy efficiency of the process of making CH3OH from CO2 and H2?) then you burn CH3OH in a fuel cell and spit back your CO2 in the atmosphere. What is the advantage of going through all this in respect to using H2 directly in the fuel cell?
Luca
Inviato: ven 04/05/2007 21.41
A: transport-...@googlegroups.com
Cc:
Oggetto: [t-i] Re: RIF: [t-i] Re: hydrogen's second coming on the road?
Michael Weidler
a.boender
by hydrogen fuel cells that produce water instead of smog and greenhouse
gases -- is a big mistake, according to George Olah, winner of the 1994
Nobel Prize in chemistry.
Olah, whose research in the chemistry of hydrocarbons has led to
high-octane fuels and more easily degradable hydrocarbons, is now
director of the Loker Hydrocarbon Research Institute at the University
of Southern California. He argues that storing energy in the form of
methanol, not hydrogen, could end our dependence on fossil fuels and
transform carbon dioxide from a global-warming liability into an
essential raw material for a methanol-based economy. Olah lays out his
plan in a new book, Beyond Oil and Gas: The Methanol Economy, published
last week by Wiley-VCH.
Technology Review: Why methanol?
George Olah: Methanol in its own right is an excellent fuel. You can mix
it into gasoline -- it's a much better fuel than ethanol. And we have
developed a methanol fuel cell.
Methanol is a very simple chemical that can be made in a very efficient
way. It is just one oxygen atom inserted into methane, the basal
component of natural gas; but methanol is a liquid material which is
easily stored, transported, and used.
TR: What's wrong with hydrogen fuel cells?
GO: Even today you could put a pump dispensing methanol at every
gasoline station. You can dispense it very well without any [new]
infrastructure. For hydrogen, there is no infrastructure. To establish a
hydrogen infrastructure is an enormously costly and questionable thing.
Hydrogen is a very volatile gas, and there is no way to store or handle
it in any significant amount without going to high pressure.
TR: But methanol is a way of storing energy, not a source of energy like
gasoline. Where will the energy come from?
GO: The beauty is we can take any source of energy. Whether it's from
burning fossil fuels, from atomic plants, from wind, solar, or whatever.
What we are saying is it makes a lot better sense, instead of trying to
store and transport energy as very volatile hydrogen gas, to convert it
into a convenient liquid. And there's a fringe benefit: you really
mitigate carbon dioxide in the atmosphere.
TR: How do you make methanol?
GO: One approach is to produce methanol by converting still-existing
huge reserves of natural gas, but in entirely different, new ways.
Today, methanol is made exclusively from natural gas. Natural gas is
incompletely burned, or converted, to synthesis gas, which can then be
put together into methanol. Now we have developed ways to completely
eliminate the use of synthesis gas.
The second approach involves carbon dioxide. We were co-inventors of the
direct methanol fuel cell. This fuel cell uses methanol and produces CO2
and water. It occurred to us that maybe you could reverse the process.
And, indeed, you can take carbon dioxide and water, and if you have
electric power, you can chemically reduce it into methanol.
So the second leg of our methanol economy approach is to regenerate or
recycle carbon dioxide initially from sources where it is present in
high concentrations, like flue gases from a power plant burning natural
gas. But eventually, and this won't come overnight, we could just take
out carbon dioxide from air.
(it continues, just google methanol economy yourself)
Gary Penn
a.boender
It is extremely accessible and gives a view on all different possibillities for energy in a systematic factual overview that sheds light on the cofusing profusion of daily front page news.
It is the best book I have read in years.
Yes Gary, I agree we should not expect one solution to the energy crisis. The answer is a lot of everything and only very very little petroleum.
Jack Slade
Gary Penn
Natural_gas). Close enough for government work? Or cooking dinner?
a.boender
Daryl Oster
source so any mistake can be reported to the source for repair.
People who make good charts are not always capable of doing math, nor are
they always technically literate, and ecen if they are, they may make
careless mistakes. The chart "gasgone.jpg" supplied by Jerry is incorrect.
It is true that a typical engine has an efficiency of 38%, so 62% is waste
heat. It is also true that typical mechanical losses are 16%, and typical
running gear loss is 10%. AND these typical losses are improperly accounted
for in the chart.
The 16% is applied to the 38% thermal energy remaining -- NOT the original
100%
The 10% is properly applied to the net engine work remaining after thermal
and mechanical losses are accounted for NOT the original 100%.
The math properly done:
100 units - 62 units of loss = 38 units of energy
38 units * 0.16 = 6.08 units of mechanical loss
38 units - 6.08 units = 31.92 units of energy
31.92 units * 0.10 = 3.192 units transmission loss
31.92 units - 3.192 units = 28.728 units left to propel the vehicle
NOT 12 UNITS as stated incorrectly in the graph.
ALSO, the 100 units assumed in the start ignore the energy required to mine,
refine, and transport the fuel.
The 28.728 units of propulsive energy are then wasted on:
* Heating up the air (aerodynamic resistance is about 75% of steady state
resistance at freeway speed).
* Heating of the tires (rolling resistance is about 25% of steady state
resistance at freeway speed).
* Heating up the brakes (= Acceleration energy, and this is very little if
on a long trip, OR a lot if in stop and go traffic conditions).
* Change in potential energy (the altitude change between origin and
destination may be positive or negative). This energy is recovered (or
lost) during a return trip.
So we have an additional loss of 28.728 units of energy, and the actual
typical net total transportation energy efficiency is zero!!! AND this is
ALWAYS true!!
Really the important number to measure is relative energy use -- NOT
efficiency. The reason is that 100% efficient transportation would use ZERO
energy (perpetual motion), and this is NOT possible.
Transportation energy use is properly compared on a passenger basis or on a
unit of cargo basis (either cubic unit, or mass unit). To make a valid
comparison, the travel time, travel conditions, and route must be the same.
Daryl Oster
(c) 2007 all rights reserved. ETT, et3, MoPod, "space travel on earth"
e-tube, e-tubes, and the logos thereof are trademarks and or service marks
of et3.com Inc. For licensing information contact: POB 1423, Crystal River
FL 34423-1423 (352)257-1310, e...@et3.com , www.et3.com
Jerry Roane
Sorry for the slow response. I had a lightning hit on my Octane SGI computer and I just now got it back to functioning. I was sweating bullets because I do my most productive work on my UNIX boxes.
http://www.chevron.com/products/prodserv/fuels/bulletin/fuel_economy/
You need to correct Chevron. That is their graph.
Jerry Roane
Guala Luca
your maths is correct and the resulting overall efficiency in the graph was in fact quite pessimistic even for an energy wasting ICE.
> So we have an additional loss of 28.728 units of energy, and the actual
typical net total transportation energy efficiency is zero!!! AND this is
ALWAYS true!!
> Really the important number to measure is relative energy use -- NOT
efficiency. The reason is that 100% efficient transportation would use ZERO
energy (perpetual motion), and this is NOT possible.
> Transportation energy use is properly compared on a passenger basis or on a
unit of cargo basis (either cubic unit, or mass unit). To make a valid
comparison, the travel time, travel conditions, and route must be the same.
Efficiency answers the question "how much energy do I get for the amount I pay?" For example, I pay 100 $ of chemical energy in the form of petrol, and get 28.728 $ in the form of mechanical energy to use as I wish. I can spend it to power a mega-wheel 4WD rock climber or a mobile coronaric unit. In the end it all ends up in heat, OK, but in the first case, I may have had a lot of fun, in the second, I may have enjoyed myself less, but I may have saved some human life. That's entirely my business, of course, and the engine designer should not waste too much time thinking about that.
cheers, Luca
Daryl Oster
Good point about efficiency being useful to compare different conversion
processes like conversion of energy. And energy conversion is an important
parameter in calculating energy used in transportation. And I see we agree
that energy consumption is the important parameter in transportation.
I am often guilty of using the misnomer "transportation efficiency", or
"efficiency of transportation". Since 100% "efficient" transportation uses
no energy at all, transportation efficiency is a misnomer (division by zero
is undefined, multiply by zero always results in zero...), so we must be
more careful to refer to energy amount and form to accomplish a
transportation task in a given time interval -- in this way valid comparison
is possible.
You also bring out the most important issue -- economic. Who cares if a
particular energy conversion process is 99.99999999% efficient; -- the real
issues are: How much energy is needed? How much will the energy cost? How
much money to recover the infrastructure costs? How much labor? How much
time? How much to clean up any pollution? How much risk? ... etc.
If there are two solar powered transportation modes capable of conveying a
load from point "A" to point "B" in "T" units of time; with one mode
requiring only one unit of energy and using a source with an overall
conversion of solar to propulsive efficiency of 1%;
AND the other mode requiring 99 units of energy provided with an overall
propulsive efficiency of 99%, we have the same requirement of solar input,
and the same transportation output.
Now if one could combine the 99% efficient solar energy converter with the
mode that only required one unit of energy, then we would have about four
orders of magnitude improvement in transportation energy effectiveness
compared with the 1% efficient energy converter with the mode requiring 99
units of energy.
Hydroelectric (HE) power plants can convert as much as 86% of the potential
energy in a flow of water between two elevations into electrical energy.
There are linear motors capable of as high as 97% efficiency in converting
to vehicle kinetic energy. If the distance from the HE plant to the linear
motor is reasonable, the transmission efficiency can exceed 90%. So we have
in existence energy conversion efficiency as high as:
0.86 * 0.90 * 0.97 = 75% efficient.
On a passenger mile basis, ETT consumes less than 1/50th as much energy at
the most efficient cars, trains, or aircraft in present commercial use.
Kirston Henderson
> There are linear motors capable of as high as 97% efficiency in converting
> to vehicle kinetic energy.
Daryl,
I know that in some cases of linear motors used in some machine tools,
etc. that permit very close (a few thousandths of an inch) inter-pole
spacing. Some really good permanent-magnet rotary motors with small
inter-pole spacing offer about 95% efficiency.
In almost any case of linear motor use for transportation vehicle
propulsion that I am aware of, the inter-pole gaps need to be much larger to
account for mechanical tolerances and resulting miss-alignments, resulting
in lower motor efficiency. Could you cite a current transportation case
that achieves an 97% efficiency?
Kirston Henderson
MegaRail®
Daryl Oster
You are correct, most LEMs are sensitive to airgap, and typical efficiency
values of LEMs used for transportation are in the high seventies and low
eighties. I did not intend to imply that there are any transportation
systems with linear motors operating at 97% efficiency, only that such
efficiencies were proven in practice. Thank you for pointing that out.
Rotating electric motors are generally more efficient (due to better gap
control). In the mid 1980s I worked for a company called Unique Mobility
(now named UQM Technologies) http://www.uqm.com/ , and was involved in the
design of a planetary reduction transmission for an electric motor that
weighed 8.0lbs and produced 40HP at 10k RPM. The motor was designed by
Unique employee Gene Fisher, and we measured energy conversion efficiencies
as high as 98% (before the gearbox) As I recall, the air gap was about .010
inch. The controller wasted about 3 times more energy than the motor
(electronics were not as developed in those days).
Keep in mind that there have been large rotating electric motors (400hp)
built that use superconductive elements that have demonstrated 99.7%
efficiency, and that is accounting for the cooling energy to keep the HTS
cold. Also, using HTS to contain magnetic flux results in much less gap
sensitivity. I am not an expert on such matters, but am in contact with
those who are.
Daryl Oster
(c) 2007 all rights reserved. ETT, et3, MoPod, "space travel on earth"
e-tube, e-tubes, and the logos thereof are trademarks and or service marks
of et3.com Inc. For licensing information contact: POB 1423, Crystal River
FL 34423-1423 (352)257-1310, e...@et3.com , www.et3.com
> -----Original Message-----
> From: transport-...@googlegroups.com [mailto:transport-
> innov...@googlegroups.com] On Behalf Of Kirston Henderson
> Sent: Monday, May 07, 2007 1:40 PM
> To: transport-...@googlegroups.com
Kirston Henderson
>
> Kirston,
>
> You are correct, most LEMs are sensitive to airgap, and typical efficiency
> values of LEMs used for transportation are in the high seventies and low
> eighties. I did not intend to imply that there are any transportation
> systems with linear motors operating at 97% efficiency, only that such
> efficiencies were proven in practice. Thank you for pointing that out.
>
> Rotating electric motors are generally more efficient (due to better gap
> control). In the mid 1980s I worked for a company called Unique Mobility
> (now named UQM Technologies) http://www.uqm.com/ , and was involved in the
> design of a planetary reduction transmission for an electric motor that
> weighed 8.0lbs and produced 40HP at 10k RPM. The motor was designed by
> Unique employee Gene Fisher, and we measured energy conversion efficiencies
> as high as 98% (before the gearbox) As I recall, the air gap was about .010
> inch. The controller wasted about 3 times more energy than the motor
> (electronics were not as developed in those days).
Daryl,
The direct-drive, permanent-magnet motors used in our MicroRail vehicle
wheels are about 95% efficient and that is pretty good efficiency. These
motors have a very small inter-pole gap. Our system does not use any
gearboxes.
I have seen presentations by several other companies in recent months
wherein they were proposing large linear-motor propelled system. As far as
I can remember, not one of them mentioned motor efficiency in the
presentations. I would really like to know approximately where such
efficiencies run. My gut feeling from my knowledge of physics and electric
motors tells me that it is nothing to brag about.
Kirston Henderson
MegaRail®
Guala Luca
Jay Andress
--
new contact info: jay.andress @monomobile.com or andress.jay @gmail.com
Jerry Roane
Most linear motors are inductive which makes the moving piece low cost. The problem is that it wastes a little energy to induce eddy currents in the plate that is repelled down the guideway. We are working on a solution to this efficiency issue but it is too early to announce our approach. The off the shelf units run in the 80s for efficiency and at 9.3 seconds of boost from the linear motor in the guideway if we go with the immediate off the shelf solution we loose approx.1 cent worth of electric power for each launch. Our motor that moves the car in the middle is a round motor for now, with high efficiency and small gap. What we think we bring to the table with our patented extrusion guideway process is dimensional accuracy where we can control the gap between the two halves of the motor. The extrusion process naturally gives a smooth trajectory that a linear motor can use to improve the energy efficiency of the system. Either way we are incredibly more efficient than any liquid fueled system but it would a nice feather in our cap to improve the efficiency and get that extra penny in the bank.
230 hp * .2 wasted for .00258333 hours = .1188 hp-hour or .08861 kw-hour or at 10 cents/kwhr =$ .00886 full retail, 22% less than a penny. A Hummer H2
http://trucks.about.com/cs/suvreviews/a/hummer_fuel04.htm
with $3.00 gas goes another 149.7 feet on $.00886 worth of gas. The large and heavy linear motor is applied directly to the lighter moving part which is why it is so much better. Improving the linear motor efficiency will be icing on the cake.
Jerry Roane
Daryl Oster
The Strickland site is a great find -- some good and valuable work -- though
obviously there is a strong rail bias. There is plenty of information that
proves that trains in the US use almost as much energy on a passenger mile
basis as the typical automobile - this data is ignored (transportation
energy data book, available online at http://cta.ornl.gov/data/index.shtml .
If one is to compare peak efficiency at crush capacity for rail, then one
must also consider that any car can carry at least double the amount of
seats minus one if operated at crush load. For example, I have seen photos
of more than a dozen passengers crushed into a VW bug. I have seen first
hand five on a moped.
Daryl Oster
(c) 2007 all rights reserved. ETT, et3, MoPod, "space travel on earth"
e-tube, e-tubes, and the logos thereof are trademarks and or service marks
of et3.com Inc. For licensing information contact: POB 1423, Crystal River
FL 34423-1423 (352)257-1310, e...@et3.com , www.et3.com
> -----Original Message-----
> From: transport-...@googlegroups.com [mailto:transport-
> innov...@googlegroups.com] On Behalf Of Guala Luca
> Sent: Monday, May 07, 2007 3:26 PM
> To: transport-...@googlegroups.com
Jerry Roane
I noticed his conclusions came up with -- ride a bike. I would like to see a repeat of your information with references that takes bicycle energy via the human food chain to counter the idea that we can bicycle our way out of this mess. Farm energy being the difference in fertilizers, food handling and processing to create the extra BTUs we need to power our travel with our legs. What I have noticed on all these topics that ridership is the key pro or con. That crush number is in the third world if you read the fine print. I prefer not to be crushed to make the difference between 5 cents per mile and .1 cents per mile energy cost. I have no faith in the numbers because they ignore the miles those vehicles do empty unlike the Oakridge numbers. The biggest discrepancy is the door to door trip. If you are riding a rail line from one city to another you still have to pay for other modes of transportation to get you where you really meant to go. You may even backtrack to get to your true destination. Implied in this message is the clear preference of the public to ride 1.2 passengers per grouping of seats. I tend to believe the Oakridge National Lab information more than an advocate for heavy rail. I did put my name on the list to get the next edition. Thanks for the link.
The more shocking entry will be to include the accompanying graphs that show the various air pollutants for each of these transportation modes. Especially ocean shipping. Again real ridership drives this whole thing. Rail advocates are justified in showing a strong ridership because they advocate we ride so I cannot fault them completely. If rail travel was as fast and cheap and door to door as cars then it would not need advocates. What the energy portion of rail shows is that steel wheels on metal guideway is pretty good at moving things with low energy. The big box concept that comes along is a negative. If they can break the rail advantage apart from the big box negative then they have PRT/dual mode.
If we wanted to win the energy war we would slow our cars down and kick BTU butt but then we would have to build more guideway and waste everybody's time going slow. Our car at 88 mph and four seated passengers gets the energy equivalent of a crush zone train. Check out this train -- http://www.interet-general.info/IMG/bangladesh-train-2.jpg
Jerry Roane ;-)
Eric Baumgartner
| Service | Source figure(s) | Average energy usage | Typical passenger load | All seated | Crush Capacity | |||||
| MJ/km | L/100 km | mpg | Passengers | Passenger-mpg | Passengers | Passenger-mpg | Passengers | Passenger-mpg | ||
| gasoline equivalent | gasoline equivalent | gasoline equivalent | gasoline equivalent | gasoline equivalent | ||||||
| Diesel bus in local and express service in Vancouver, BC, Canada | BC Transit 1994/95 fiscal year operating statistics: 29,161,885 L diesel fuel for 45,582,954 vehicle-km. All buses 40' except for a small number (<3% of fleet) of 60' | 24.3 | 76 | 3.1 | 25 | 78 | 34 | 105 | 90 | 279 |
| Mode | Passenger-miles per gallon |
|---|---|
| Rail | 
600
|
| Trolleybus |
230
|
| Diesel bus | 78
|
| Scooter/light motorcycle | 75
|
| Smart fortwo cdi | 74
|
| Toyota Prius | 72
|
| Ford Explorer | 21
|
eri...@shaw.ca
Jay Andress
@monomobile.com or andress.jay @gmail.com
Jerry Roane
We are at the same place on motors. I am wishing to use the Unique Mobility rotary motor with a traction drive tire on the middle section of the guideway. I am using a roller coaster linear motor for the launch that lasts 9.3 seconds so I can stand the inefficiency of the off-the-shelf version. I do have to disagree with one statement in your post mostly on principle. "You cannot do it." Of course it can be done. The difference is the time, money and effort to make it happen is a variable that is hard to predict. I can think of ten ways to maintain the gap I am sure you can too if you put your mind to it. I once worked for a French parent company making computerized credit cards and they kept using the phrase "that is impossible" when something was difficult. I finally figured out that the translation they learned was incorrect. We got that straightened out so they quit saying that everything that we were about to do was "impossible".
The heaving is just motor control and is not inherently a part of the operation of a linear motor. Electronics can easily feather in the power applied to slow or speed a vehicle. That part is a piece of cake.
I am curious on your expected drag using a 50 hp motor running it maxed out at 50 hp at 100 mph. If you have a regular car shape with a regular car frontal area it would appear that 50 hp is not quite enough to run 100 mph. Will you have sufficient cooling air on hot days to run flat out all the time? What efficiency loss do you simulate using a traction wheel?
Jerry Roane
Jay Andress
Jerry Roane
At the risk of posting too many in a day---
The cars hit the ramp at 40 mph
The frontal area is 14.285
The Cd is .14 for the wheels out version
The only speed allowed on the guideway is 180 mph
The horsepower to operate the car at 180 mph is 81.5 hp
This power applied for 6 minutes moves the car 18 miles which traverses most cities in a generally straight line.
The power suppled for this 6 minutes is all the energy storage system needs to store for 18 miles and then it gets a whole new charge.
The acceleration of this car from 40 mph to 180 mph is .69 Gs this somewhat arbitrary figure results in a 1,500 foot long linear motor
(initially I had a 1,000' long linear motor but I caught a lot of grief for the higher acceleration so I compromised (I hate that!!!) )
I have three sources for the linear motor one of them is your source another one is from China and the third one is still confidential.
I talked with the company that used to be called Unique Mobility and they have the motor you mentioned but we were wanting to have them create a larger version of their standard motor. If that falls flat the Prius electric motor is 78 hp which is very close to our 81.5 requirement. Let me be clear here--- the TriTrack is in development and not every last detail is completed but each parameter is framed and bracketed. If I could not find a large enough single motor I would simply use two of your motors and not use them at full output. I do have a thermal plan for keeping these efficient motors cool. The good news is that the more efficient the motor the less thermal transfer you need as I am sure you know.
Your frontal area explains your energy levels. 100 mph is not all that fast on a guideway. My Prius goes 100 mph and gets excellent mileage doing it. We are so trained by our conditioning that 100 mph is scary fast when in fact it isn't unless the pavement is wet. Drafting will not get you anywhere unless you join the forms into one form then you have to beef up the structure to hold back the inertia of all the following cars. That 60% lower figure is false for safe operation. If you have wind tunnel data on that following distance I would be interested in that information. The military report I found on high speed trains shows that each added car adds .1 to the Cd and since my drag coefficient is below .1 it would be worse to draft than to run in clean air. (non-turbulent air) The EPA is funding a study right now on Mac Trucks and the gap between the cab and the box. That EPA study will shed light on the idea of a poor aerodynamic form following another poor aerodynamic form. The simulation I saw of these setup shows a tornado forming between the cab and the box that goes up above the cab several feet. If you stand on an overpass and let trucks go under you you will feel this funneled air blast. I see no reason this tornado would not form on boxy cars following a few inches apart. The litigation you get into on the first crash of a following car will end your company so why take the risk for so little gain? Does this help fill in the gaps? There are a few other subtle alterations to these gross numbers like the air hockey effect of the car underbelly to the guideway and the traction of the drive wheel sucking off some of the power that will be refined as we go along. If I do a wheels retracted car the Cd is .07 tested in the engineering basement at UT Austin. The full report of the wind tunnel test in on the web site. I won a nickel from Dr. Goldstein who bet me my drag coefficient was not that low going in. The drag number was derived in the 1920s I just brought it back out and dusted it off.
a.boender
At 11:57 AM 5/3/2007, you wrote:The Ballard fuel cell used in the mercedes is fueled by methanol. The rare fuel cells in laptop's and cell phones are DMFC's running on methanol Hydrogen is the opposit of an energy carrier. You cannot store it
Jerry,Yes, you can.You cannot transport it.Yes, you can. - Jerry Schneider - Innovative Transportation Technologies http://faculty.washington.edu/jbs/itrans
I mean of course in a economical way.
In a way that makes sense.
I have 160 liters of matural gas in my car, it takes me around for 400 km.
If it were just air under the same 200 Bar pressure it would take me in a compressed air car at least 100 km.
Hydrogen has to be carried under at least 300 Bar and if you leave it for a week a lot of it has escaped right through the container.
Or you can cool it down and that it also a big hassle.
Use methanol and you will not have any of those problems.
Arnest
Guala Luca
cheers, Luca
rot...@zahav.net.il
explains their arrow shape array.
Oded Roth
http://www.transportationet.com
Jerry Roane
In a direct measurement device like is installed on the dashboard of my Prius, it tells me the instantaneous power use of the drive train. I can follow dangerously close to a much larger semi-truck and the calibrated instrument does register a slight decrease in energy required to move the car but any energy gain that is obtained by following way too close to a semi is instantly lost if the gap between the two vehicles is disturbed by a wind gust or an incline change. Then the power has to be applied to maintain the gap and all gains are more than lost in the Prius following the Mac truck story. I can show you the instrument and take video if someone is interested. The applicable storyline is to have a Prius follow a Prius and record the dashboard instrument showing power expended. To approximate this take the relative area of the Mac truck and divide it by the area of the Prius except fluid flow dynamics are nothing like linear so it is a poor approximation. I get 50.3 mpg if I don't follow trucks. If I follow trucks I get less. How can it possibly be that you save half the power if the instrument says otherwise. How you feel on a bike has little to do with the power you are converting from expensive agricultural products. A slight increase in power output feels like a lot when you are near max output. The gym my wife joined once had a watt meter on the bike machine. It gave a direct reading of power output as you pedaled. That instrument applied to the bike would allow you to collect data points to close the scientific loop of hypothesis - prediction - experiment - white paper with one more open question in the last paragraph - funding - hypothesis etc. ;-) http://en.wikipedia.org/wiki/Scientific_method
Jerry Roane
Walter Brewer
airstream momentum deflection, from the bird ahead?
Walt Brewer
----- Original Message -----
From: <rot...@zahav.net.il>
To: <transport-...@googlegroups.com>
Sent: Wednesday, May 09, 2007 1:38 AM
Subject: [t-i] RIF: [t-i] Re: Linear Motor Efficiency
> Flocks of wandering birds know the aerodynamic rules - It
Walter Brewer
built between railroad track rails while following a railroad car at some
high speed.
Cheating? Wonder how many BTU the train used compared to the biker?
Walt Brewer
----- Original Message -----
From: "Guala Luca" <gu...@systematica.net>
To: <transport-...@googlegroups.com>
Sent: Wednesday, May 09, 2007 12:14 AM
Subject: [t-i] RIF: [t-i] Re: Linear Motor Efficiency
Guala Luca
If the wing extremity vortex of the bird in front of you is centered around your body (I am supposing that "you" is a bird) you get a net decrease in drag. If you also choose the correct distance, the vortex does not influence your wings so you do not have to spend more energy to stay in flight. Birds know all this.
Also prop airplanes used to fly in similar formations but in the case of prop planes the advantage was not as great as for birds for two reasons: one is that a crash between two airplanes generally results in the death of all the occupants, which is not the case with birds that are much more resilient. The second is that if the propeller is on the nose of the airplane, it will lose efficiency by screwing into a vortex therefore increasing the power necessary to stay in flight.
cheers
Luca
-----Messaggio originale-----
Da: transport-...@googlegroups.com per conto di rot...@zahav.net.il
Inviato: mer 09/05/2007 10.38
A: transport-...@googlegroups.com
Cc:
Oggetto: [t-i] RIF: [t-i] Re: Linear Motor Efficiency
Jay Andress
Walter Brewer
written evidence on this subject?
Agree the parasite drag flow is very small, but so is the wing tip vortex;
probably less than 1/20 wing span. The downwash flow sheet is as wide as the
whole wing span.
Also these factors oscillate zero to max. for a flapping wing. Are birds
clever enough to stay in the zero downwash zone?
Walt Brewer
----- Original Message -----
From: "Guala Luca" <gu...@systematica.net>
To: <transport-...@googlegroups.com>
> Flocks of wandering birds know the aerodynamic rules - It
Guala Luca
About birds being clever enough to etc etc... the answer is yes, they are. It doesn't take so much brains, which birds it is well known are not much endowed, but sensors ont he skin and the appropriate and appropriately fast feedback system, which I am aware is monitored by the cerebellum, not by the main brain.
Millions of year of evolution made (most) birds pretty efficient flying machines. For example, a bird knows when the wing is stalling by feeling the feathers raise on the top side of the wing. If you consider how sensitive the hairs of your arm are to a breeze, you can imagine how precisely a bird can control stall.
cheers
Luca
-----Messaggio originale-----
Da: transport-...@googlegroups.com per conto di Walter Brewer
Inviato: mer 09/05/2007 17.14
A: transport-...@googlegroups.com
Cc:
Oggetto: [t-i] Re: RIF: [t-i] RIF: [t-i] Re: Linear Motor Efficiency
Guala Luca
I find it rather unfair from you to bring out the "scientifical method" in this discussion. Much of science (though not all) is about making experiments. I have been experimenting drag forces and the mechanics of locomotion for about 25 years, using a very precise instrument: my own body. It does not give digital metric readings, it cannot be connected to a computer (it could not at the time of my experiments, it can now) but I assure you, it was able to tell me exactly the best spot to stay behind a bicycle in order to have a HUGE advantage in power consumption. I could tell not only the different effect when changing position, but even when going from behind a short cyclist to behind a taller one (unfortunately, me being rather tall, I was often chosen to stay in front). It was not merely a feeling: when you race for 4-5 hours you can't rely on feelings. Only experience tells you how to interpret those "feelings", how to behave and what are the results.
And nothing is better than scarceness of a resource if you want to learn how to save it. When you have 50 Hp you can waste a bit of it. Or do your calculations roughly. When you have 1/3 of Hp on the tap you must find every way to save it and believe me, there are ways.
If racing bicycles were allowed to be of any shape, and have aerodynamic appendices, they would probably look like recumbents... without a fairing! For the simple reason that when you rely on so little power even the added weight of a nose cone can bee too much on a typical European race course, which includes lots of hill climbs (and phisical limitations to the speed you can achieve coasting downhill). Of course if the race was held on a flat course, things would be a lot different.... and a lot duller!
the reason why a bird is round and a truck is square is simple: it's about internal space. Birds do not usually ingest lots of square objects and they do not have to maximize their volume under constraints of length, width and height. In the case of airplanes, a very tough compromise must be found so that in some case the aerodynamic guys have it their way and the plane comes out with a round fuselage (e.g. Boeing 747 Cargo) while in others the mechanical team has its way and the airplane comes out square shaped (e.g. Lockheed Hercules).
there is another reason of course: birds and airplanes move in a 3 dimensional environment, trains, trucks and cars don't. The effect of the road or track surface underneath is significant. The best aerodymanic shape running on a flat surface is HALF of a rotation solid. Refer to aerodynamics books for this.
Your Prius is shaped (apparently) very well in aerodynamic terms - if you look it from the side - but it has slab sides and a hatch tail. Why? Because if the sides were round it would have an unacceptable headroom. And even with all its nice aerodynamical shape, the designers had to add a spoiler to the rear, which cuts the rear windscreen horizontally in two. That spoiler is needed to prevent the turbulent wake from the hatch back to creep up the roof and spoil all the cute aerodynamic job. The Prius is not an aerodynamic shape the way aeronautical engineers mean it: it's a blunt shape, although certainly not as blunt as a truck. To make it truly aerodynamical it would have had to be longer and/or lower, which would have made it pretty much unsellable.
If you want to know more about aerodynamics, I can point you to several books. Theoretical and experimental aerodynamics is an old science. some books written in the 30's and 40's are still studied at University courses (well, they were in the 80's) but I am sure you know a lot (although I realized from some past statements of yours that a quick look at H. Schlichting's classic book on boundary layer theory could do you some good). However, I invite you get out of your lab and do more experiments: jump on a human powered vehicle and go FAST !
cheers
Luca
-----Messaggio originale-----
Da: transport-...@googlegroups.com per conto di Jerry Roane
Inviato: mer 09/05/2007 16.10
A: transport-...@googlegroups.com
Cc:
Oggetto: [t-i] Re: RIF: [t-i] Re: Linear Motor Efficiency
Jerry Roane
From-- http://www.howstuffworks.com/framed.htm?parent=question658.htm&url=http://www.ent.ohiou.edu/~et181/hpv/hpv.html
The Human Engine
Consider now the human engine. In 1983 Douglas Malewicki gave a landmark paper at the International Human Powered Vehicle Association Scientific Symposium, in which he presented a graph showing the maximum duration of human effort for various steady power levels. This graph has been reproduced below for convenience. Notice from the graph that an average "healthy human" can produce a steady 0.1 horsepower for a full eight hour period, while a "first class athlete" can produce 0.4 horsepower for a similar period. Note that each data point on the curves represents an exhausted human. No more power is available without some rest and recovery. Thus at 0.4 hp the "healthy human" becomes exhausted within 10 minutes! Try to decide where you fit in this curve.
Note that in the power equation the units of power is watts (W), however we can apply the conversion 0.1 hp = 75 W (approximately) in reading the graph. Once you have decided the steady power level that you can comfortably apply at the pedals, it would be of interest to know the velocity that you will achieve at steady state when all other parameters are maintained at constant values. Unfortunately the steady state power equation above cannot be solved explicitly for velocity, thus we will develop a root finding technique to solve this problem in a forthcoming exercise. This first exercise introduces modular programming using functions, and is much less ambitious:
Now lets say you are Lance Armstrong and you can sustain .4 hp for 8 hours and you win the race. Now lets compare a set of 4 novice riders competing in a relay race against Lance at .2125 hp for 8 hours before they all drop from exhaustion. The difference in human effort between the two is .1875 hp. Now compare this difference between winning bike and loosing bike the total you have to pull from is less than the cigarette lighter in your car. My point is that bicycles are extremely energy limited and even if you feel like half your energy is being saved by drafting that is still an insignificant amount of power when you apply it to a PRT or dual mode car. The energy you gain by drafting a bicycle would not push one rear view mirror on a PRT or dual mode car at useful speeds. If four bike riders equal one car's worth of draft then the maximum total for Lance has to be under 1.6 horsepower and more like 1/10th of that for the gain from draft otherwise the following bike would be instantly sucked up into the tail of the lead bike. Now apply this draft power to your PRT at .16 hp and there is a first approximation of the gain of drafting. A wind tunnel test is required to get an answer.The biggest difference in PRT or dual mode aerodynamics and airplane aerodynamics is we do not want lift and we are going subsonic. To get the data on fuselage at subsonic speed you have to go back in time to the 1920s when that was the state of the art and hundreds if not thousands of men were working in the problem and they used wind tunnels to rectify their pontification to the measured reality. If you want to learn about Class C airship body forms with the optimal aspect ratio for volume per drag just look at the shadow cast by the TriTrack or look up the study done by the US Navy in 1929.
More importantly safety trumps saving even a full 1.6 horsepower so the idea of putting human lives at risk just to pick up some stray energy is dangerously flawed. The following-close reduced collision idea is even worse for a string of cars more than two. The collision would have a whiplash effect so the further back in the wreck the more severe the forces on the undercarriage of the car and the worse your neck will snap back and forth. One neck brace would counter the energy cost savings 1000 fold once it made it through the court system. The beefing up of the undercarriage and added weight would waste the rest of the energy gain.
Jerry Roane
Guala Luca wrote:
Jerry Roane --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "transport-innovators" group. To post to this group, send email to transport-...@googlegroups.com To unsubscribe from this group, send email to transport-innova...@googlegroups.com For more options, visit this group at http://groups.google.com/group/transport-innovators?hl=en -~----------~----~----~----~------~----~------~--~---
Guala Luca
> Thus at 0.4 hp the "healthy human" becomes exhausted within 10 minutes! Try to decide where you fit in this curve.
> My point is that bicycles are extremely energy limited and even if you feel like half your energy is being saved by drafting that is still an insignificant amount of power when you apply it to a PRT or dual mode car.
> The biggest difference in PRT or dual mode aerodynamics and airplane aerodynamics is we do not want lift and we are going subsonic.
> To get the data on fuselage at subsonic speed you have to go back in time to the 1920s when that was the state of the art and hundreds if not thousands of men were working in the problem and they used wind tunnels to rectify their pontification to the measured reality. If you want to learn about Class C airship body forms with the optimal aspect ratio for volume per drag just look at the shadow cast by the TriTrack or look up the study done by the US Navy in 1929.
> More importantly safety trumps saving even a full 1.6 horsepower so the idea of putting human lives at risk just to pick up some stray energy is dangerously flawed.
cheers, Luca
Jerry Roane
I think we are together on these points. I do have one other very minor
point that there is not a length restriction but more of a swept width
as you corner on streets restriction. Examples stretch limo and maglev
train
Automotive fashion is fleeting. The "looks funny" phase lasts between
two years and never, for most body styles. Presently the art majors
design car bodies and the aero guys get a crack at it last. I propose
the government legislate minimum requirements for Cd and let the aero
guys slug it out with the art guys to produce car shapes that work well
enough to be allowed on the public roadways. Usually I am a right
winger but on the topic of auto aero I believe it will take legislation
to push fashion in the right direction. If all the car bodies have to
meet minimum requirements for not wasting money and energy then it will
be an even playing field. Creativity in styling will be tempered with a
dose of measured engineering reality. The corners you knock off will
not be missed. It is usually dead volume in almost all cars. The human
form is not a box and your head is not attached from your left shoulder
when sitting in the driver's seat. A legislated Cd of .16 would be a
good starting point for the discussion. It would cost the government
zero dollars to pass this law plus the cost of paper. It would save the
world millions if not billions in downstream benefit.
You are correct about better forms in more recent NASA work. The better
forms have a more bulbous middle shifted forward and the tail sucks in
some before the tip. The best way I can describe this shape is to use
imagination to morph a blue whale shape onto a class C airship. The
shapes are very similar but from a "looks" ;-) standpoint I like the one
I use. It will come out of the one piece mold better than that more
complex shape NASA has developed. From a patent standpoint it is
similar enough that it is still covered by the patent claim. You have
to be considerably different to get around a patent claim. You can't
just knock off a design and pull here and tuck there. The patent claim
is broader and covers both. The guideway slopes away from the car body
making the 3D exit of air from the body more like 3D flight. Closed or
covered guideway will have a disadvantage on energy efficiency because
the air is more trapped. At slower speeds it makes essentially no
difference.
Jerry Roane
snip
Guala Luca
> A legislated Cd of .16 would be a
good starting point for the discussion. It would cost the government
zero dollars to pass this law plus the cost of paper. It would save the
world millions if not billions in downstream benefit.
> The guideway slopes away from the car body
making the 3D exit of air from the body more like 3D flight.
Sorry for nagging you here, but I think the guideway DOES make a difference
cheers, Luca
Jerry Roane
I ain't asceered! Actually I am acting in the best interest of the
automakers so the mob does not do that to them and their dogs for
blowing the planet and creating future oil wars. Have you seen "Who
Killed the Electric Car"?
The idea of creating an engineering metric piece of legislation is so
all the car companies would be on a level playing field. They would be
able to design anything they wanted AS LONG AS it was a good design. I
see no harm in that. They have to design new cars all the time, if they
want to sell anything. The difference is that because they all have to
do better at the same time the "looks funny" part of aerodynamic design
would be lessened. The CAFE standard is the same idea but poorly
implemented. Rather than legislate downstream parameter like "fleet
mpg" The actual engineering performance metrics should also be included
so car fashion can be pushed into the 21st century.
I saw the diesel engine manufacturer's lobby guy at an EPA summit. He
was so full of shit his eyes were brown. First he stood up in the
convention and told us how the engines were so clean they couldn't
measure them. Later he told us that the diesel engines could not meet
the next bump up in air pollution performance. He came across as an
advocate with no technical backup which I guess is what a paid lobbyist
does.
My dog would piss on their feet. He pees on everything else. ;-)
On a side note-- I went to see the Disney 3D movie Meet the Robinsons.
It had PRT cars in the future scene and the main car they traveled in
time had a top similar to the TriTrack. You should take your kids, or
grandkids, or neighbor kids as an excuse to go see this cute movie.
More importantly the wind tunnel testing was done with the guideway
under the car but not touching the car. The stinger holding the car was
supported from the articulating mechanism that can measure aircraft
pitch yaw and roll while the guideway was supported from below on a
special table that we constructed. The interaction of the guideway and
the car body was the main point of study. I have lots of pictures and
memories of the interaction of the air as it flows over the body nose
and splits along the triangular guideway without making eddy flows. If
you are interested I can send you all the pictures I have of the two
days we spent testing the solid aluminum 1/12th scale model. They fill
up a CDR. Attached is one image of the group. What is not obvious in
the image is that the body is mounted from the rear (dog joke here) and
the guideway is mounted from below and they do not touch in the middle.
The body shape is accurate within .001" and was cut on a combination of
hand lathe and CNC lathe. There was one flaw that I had to primer over
when I was working the lathe and someone asked me a question at the same
time I got a cell phone call and as I turned around to answer the
question I turned the hand crank the wrong direction cutting a .001"
ring around the middle of the model. After a few hours of primer
buildup and sanding I had the mistake repaired. The next level of
sophistication in the wind tunnel would be to do a 1/4 scale in the
large wind tunnel at UT Austin J. J. Pickle. That much larger wind
tunnel was being repaired at that time. If I did a 1/4 scale car (5
feet long) I have designed a guideway with moving belts to simulate the
guideway surface being one speed and the car being another. John
Harding of the US DOT railroad side did not believe any of my data and
he insisted that the guideway had to move like they did at a Virginia
university on the USDOT funded study of the US high speed train. The
guideway would be rubber belting and the motors to drive the guideway at
speed were air motors with high RPM capability. I had a spot reserved
for the large wind tunnel after a Cessna model but got distracted by
other things. I know the belts simulating the guideway surface speed
would higher fidelity but since I have had zero funding support that
will have to wait. Maybe that car maker's lobby could fund the wind
tunnel test at 1/4 scale with the moving guideway surface. hehehe Dr.
David Goldstein oversaw the team doing the wind tunnel testing and he
knows what he is doing. He developed the microgroove skin for airplanes
and I was spouting off about microgrooves as a way to reduce drag and he
pulled out a roll of the stuff he had developed earlier. I was truly
impressed.
I am waiting for the check to clear and permission to announce about the
street version. Big things a brewin'
Jerry Roane
Daryl Oster
You have your team of world class athletes take terns drafting one another
on standard (unaerodynamic) bikes, and I (a non athlete) will ride an
aerodynamically efficient HPV like the Varna
http://www.varnahandcycles.com/hpv/hpv2.htm
on a 200 mile race with no one to draft. BTW, a good athlete can achieve
83mph on the Varna on flat ground in no wind conditions.
An aerodynamic vehicle like a varna still imparts quite a bit of energy to
the air. It would do only little good for one varna to draft another -- the
reason is that the efficiency would be reduced due to unsteady airflow --
increasing the drag coefficient.
Daryl Oster
(c) 2007 all rights reserved. ETT, et3, MoPod, "space travel on earth"
e-tube, e-tubes, and the logos thereof are trademarks and or service marks
of et3.com Inc. For licensing information contact: POB 1423, Crystal River
FL 34423-1423 (352)257-1310, e...@et3.com , www.et3.com
> -----Original Message-----
> From: transport-...@googlegroups.com [mailto:transport-
> innov...@googlegroups.com] On Behalf Of Guala Luca
Daryl Oster
shear between the tritrack vehicle and the guideway, and this will
substantially reduce the efficiency. The way to test this in a windtunnel
would be if the guideway surface moved in relation to the vehicle at the
wind speed (like a couple of conveyer belts set at a 60 degree angle - tough
to do).
Daryl Oster
(c) 2007 all rights reserved. ETT, et3, MoPod, "space travel on earth"
e-tube, e-tubes, and the logos thereof are trademarks and or service marks
of et3.com Inc. For licensing information contact: POB 1423, Crystal River
FL 34423-1423 (352)257-1310, e...@et3.com , www.et3.com
> -----Original Message-----
> From: transport-...@googlegroups.com [mailto:transport-
> innov...@googlegroups.com] On Behalf Of Guala Luca
> Sent: Thursday, May 10, 2007 6:11 AM
> To: transport-...@googlegroups.com
Daryl Oster
> -----Original Message From: Jerry Roane; Sent:May 09, 2007 12:36 PM
> To get the
> data on fuselage at subsonic speed you have to go back in time to the
> 1920s when that was the state of the art and hundreds if not thousands of
> men were working in the problem and they used wind tunnels to rectify
> their pontification to the measured reality. If you want to learn about
> Class C airship body forms with the optimal aspect ratio for volume per
> drag just look at the shadow cast by the TriTrack or look up the study
> done by the US Navy in 1929.
The old airships are not even close to optimum -- there have been many
significant gains in subsonic aerodynamics of bodies of revolution.
Submarines are one area, and there are several others too. Modern forms
generally maximize the length of laminar flow along the body, and cusp the
trailing edge to minimize wake while maximizing pressure recovery. By
contrast, the 1920s and 1930s forms were based on turbulent flow dynamics,
and the pressure recovery was not optimized. Another big difference is that
an airship is ALWAYS facing into the relative wind and never operates in a
side wind -- therefore they can be designed with little need to conserve
dynamic force to allow for angular momentum and avoid flow separation when
operating at an angle of attack to the relative wind.
> Guala Luca wrote:
>
> If racing bicycles were allowed to be of any shape, and have
> aerodynamic appendices, they would probably look like recumbents...
> without a fairing! For the simple reason that when you rely on so little
> power even the added weight of a nose cone can bee too much on a typical
> European race course, which includes lots of hill climbs (and phisical
> limitations to the speed you can achieve coasting downhill). Of course if
> the race was held on a flat course, things would be a lot different....
> and a lot duller!
Stupid racing rules are the reason -- HPV races have no rules that limit
shape or structure -- most other races have rules that say "no farings" or
"must use a diamond frame of standard design".
It is well known that structurally a shell is much more mass efficient than
a space frame -- the radius of gyration is much greater for a given amount
of material; for this reason, and also for aerodynamic reasons I do not
agree with your guess.
> there is another reason of course: birds and airplanes move in a 3
> dimensional environment, trains, trucks and cars don't. The effect of the
> road or track surface underneath is significant. The best aerodymanic
> shape running on a flat surface is HALF of a rotation solid. Refer to
> aerodynamics books for this.
This is not true -- a half revolution would have much more shear force in
the boundary layer under the vehicle and above the road surface. The ideal
shape will minimize the amount of area subject to this shear force between
road and vehicle. Also, a half revolution body will have high lift force --
another problem for a road vehicle.
> -----Messaggio originale per conto di Jerry Roane
> I never see birds following nose into tail ...
Land based birds draft single file -- just watch the penguin movie ;-D
Daryl Oster
train philosophy, and/or continue a life of aerodynamic sin so prevalent in
the world.
Platoons rely on other vehicles aggregated and going to the same location --
(sounds like a train, and subject to most of the same limitations UNLESS
very complex, precise, (and expensive) controls are employed.
Much of the time, the demand is far from peak, and most of the time vehicles
will NOT naturally group between common origins and destinations.
Platoonoing is CONTRARY to the main tenets and philosophies of PRT --
individual vehicles from random origins and to random destinations safely
sharing a common guideway at minimum expense.
Platoonoing has more disadvantages:
For a given capacity; shorter vehicles, in noise to tail platoons, impart
far greater loading on a span than longer aerodynamically shaped vehicles
operating with consistent spacing. The loading applies to both vertical
force and horizontal force of side wind or curve.
Vehicles in a platoon require more wait time to aggregate platoons.
More power is required for the lead vehicle, (or lone vehicle) -- increasing
the power supply requirements to several times greater than if vehicles of
the same capacity were aerodynamically optimized on an individual basis.
Any vehicle may be called upon to lead a platoon (or operate individually),
therefore the motor must be sized at double or triple the size of the
average need, and up to 10 times bigger than an aerodynamically optimized
vehicle of the same capacity.
Longer time interval for a merge to take place -- a merging vehicle must
wait for the entire platoon (train) to pass before a merge can occur (or the
platoon must split -- involves precise position and individual velocity
control that is contrary to fixed design speed approach (natural bank angle
no longer possible, etc).
Laminar drag force is about half of turbulent drag force. Laminar flow over
a platoon cannot be expected due to the boundary layer disturbance between
vehicles in the platoon; therefore the sum of drag of a platoon will always
be greater than the same number of vehicles individually optimized for the
lowest individual aero drag.
In short, platooning PRT vehicles offers negative benefit to cost ratio
compared with vehicles aerodynamically optimized individually.
Daryl Oster
(c) 2007 all rights reserved. ETT, et3, MoPod, "space travel on earth"
e-tube, e-tubes, and the logos thereof are trademarks and or service marks
of et3.com Inc. For licensing information contact: POB 1423, Crystal River
FL 34423-1423 (352)257-1310, e...@et3.com , www.et3.com
> -----Original Message-----
> From: transport-...@googlegroups.com [mailto:transport-
> innov...@googlegroups.com] On Behalf Of Guala Luca
> Sent: Wednesday, May 09, 2007 2:19 PM
> To: transport-...@googlegroups.com
> Subject: [t-i] RIF: [t-i] Re: RIF: [t-i] Re: RIF: [t-i] Re: Linear Motor
> Efficiency
>
Guala Luca
> You have your team of world class athletes take terns drafting one another
on standard (unaerodynamic) bikes, and I (a non athlete) will ride an
aerodynamically efficient HPV like the Varna
http://www.varnahandcycles.com/hpv/hpv2.htm
on a 200 mile race with no one to draft. BTW, a good athlete can achieve
83mph on the Varna on flat ground in no wind conditions.
I got the point that Jerry R. made, and I agree with him, that you cannot extrapolate the result for one class of vehicles and apply it to another class. HPV's are very underpowered vehicles, their performance require some tough compromises. Motorized vehicles can do with some simpler aerodynamics.
the subject of aerodynamic HPV has been discussed thoroughly elsewhere and of course everyone agrees that the traditional bike is hardly the best design, but for a few tough conditions (for example very steep hills and off-road). In some races in Norway, recumbents were allowed to race along with traditional bikes several years ago. Even the earliest recumbents were a lot faster than traditional bikes on the flat and downhill, but they were slower uphill, not only for the extra weight (merely the seat is about 5-10 times as heavy as a racing bike saddle - although a lot more comfortable) but also for the less efficient riding position. Then recumbents started to get better designed and lighter... and started to win consistently. Therefore they have been banned again!!!
> An aerodynamic vehicle like a varna still imparts quite a bit of energy to
the air. It would do only little good for one varna to draft another -- the
reason is that the efficiency would be reduced due to unsteady airflow --
increasing the drag coefficient.
ciao, Luca
Guala Luca
> It is well known that structurally a shell is much more mass efficient than
a space frame -- the radius of gyration is much greater for a given amount
of material; for this reason, and also for aerodynamic reasons I do not
agree with your guess.
ciao, Luca
Jerry Roane
Small point and then I will shut up for the day. The velocity vector
of a 12 mph side wind combined with a 180 mph forward velocity. Is
pretty much a 180.4 mph wind on the front at an angle of 3.814 degrees.
In the wind tunnel you puff smoke to look for actual evidence of what
you mention. Since I have the advantage of playing in the wind tunnel I
can give first hand observations of smoke flowing over the TriTrack and
guideway combination. I have pictures of some views of the smoke
flowing over the entire body form but since I was there with 6 other
observers and experimenters I did not see any turbulence on the whole
body. The separation may actually be on the tip of the tail on the rear
of the car but in the wind tunnel the stinger was big enough that it
occupied the volume where the phenomenon you speak of might have
happened if the stinger rod had not been in the way. As a control we
did observe all these things on the outrigger wheel fenders. I do have
photographs of the turbulence leaving the rear edges of the fender and
outrigger tire. In the testing I removed the outrigger wheels and the
team made more measurements. End results -- the two outrigger tires had
essentially the same drag as the entire car body. The difference in
volume being huge between the 20 foot long body shell and the encased
tires.. Unlike a stunt airplane the fuselage stays flat with the
terrain and the wind does not blow up or down. The side wind is only in
the X-Y plane for the most part. We twiddled with the angle of attack
and it made no difference that could be seen at 1/12th scale.
I quizzed Dr. Goldstein at length about the Virginia test with the
moving surfaces. (simply three conveyor belts on three air die
grinders) He did not feel it would make any difference in the
measurements. My guess is his opinion carries more weight. John
Harding on the other hand held strongly to your opinion that the
guideway belts are required. It was John Harding who single handedly
killed the USDOT effort to even look at elevated guideway cars. You can
thank him for $3.00 gas with no hope of a national solution. His name
most likely will be memorialized in the receptacle that accepts the
parking trolley. ;-)
Jerry
Daryl Oster wrote:
> snip
>
> Another big difference is that
> an airship is ALWAYS facing into the relative wind and never operates in a
> side wind -- therefore they can be designed with little need to conserve
> dynamic force to allow for angular momentum and avoid flow separation when
> operating at an angle of attack to the relative wind.
>
>
snip
Daryl Oster
The improvements offered by HTSM, linear motors, and the need for a "one
network" solution indicate that this mechanical option will not be likely
used for ETT, but you may find it interesting:
The ETT patent discloses the use of low power rotary motors powering large
flywheels operating between two tubes in the ETT guideway to propel the
vehicles AND also recover and transfer energy from inbound vehicles to
outbound vehicles via contact means. This would only work well for
relatively low (for ETT) speeds below about 300mph; it would also require
much more maintenance and replacement of wear surfaces.
Also disclosed in the ETT patent document is the need to keep the resultant
acceleration force closely aligned and balanced across the center of gravity
(CG) of the vehicle. If a LEM force is not applied along the CG of the
vehicle, it will react pitch or yaw forces into the suspension; and cause
higher peak suspension forces and displacements, and/or motor misalignments
and increase the gap requirements (and cost, and complexity).
Just by surveying existing state of the art in LEMs and constrained by the
capabilities of HTSM, we are confident that through proper design we can
maintain LEM gaps sufficiently low to result in efficiency greater than 90%,
and likely as high as 97% WITHOUT use of superconductor elements. NOTE:
HTSM uses superconductive elements, and the use of SC motor elements too
could result in motor efficiencies as high as 99.7% with presently proven
technology.
The use of SC in the acceleration/deceleration LEMs for ETT is only
justified in the case of design speeds over about 600mph. (NOTE: the
kinetic energy of a 1200lb ETT capsule traveling at 600mph is about the same
KE of a 40T truck moving 70mph.) At a design speed of about 1800mph, the
use of SC motor elements becomes necessary to avoid too much motor waste
heat being rejected to the capsule.
Daryl Oster
(c) 2007 all rights reserved. ETT, et3, MoPod, "space travel on earth"
e-tube, e-tubes, and the logos thereof are trademarks and or service marks
of et3.com Inc. For licensing information contact: POB 1423, Crystal River
FL 34423-1423 (352)257-1310, e...@et3.com , www.et3.com
> -----Original Message From: Jay Andress
Jay Andress
Bruce A. McHenry
Platoons rely on other vehicles aggregated and going to the same location --
(sounds like a train, and subject to most of the same limitations UNLESS
very complex, precise, (and expensive) controls are employed.
...
Platoonoing has more disadvantages:
For a given capacity; shorter vehicles, in noise to tail platoons, impart
far greater loading on a span than longer aerodynamically shaped vehicles
operating with consistent spacing. The loading applies to both vertical
force and horizontal force of side wind or curve.
,,,
More power is required for the lead vehicle, (or lone vehicle) -- increasing
the power supply requirements to several times greater than if vehicles of
the same capacity were aerodynamically optimized on an individual basis.
Any vehicle may be called upon to lead a platoon (or operate individually),
therefore the motor must be sized at double or triple the size of the
average need, and up to 10 times bigger than an aerodynamically optimized
vehicle of the same capacity.
Longer time interval for a merge to take place -- a merging vehicle must
wait for the entire platoon (train) to pass before a merge can occur (or the
platoon must split
-- involves precise position and individual velocity
control that is contrary to fixed design speed approach (natural bank angle
no longer possible, etc).
Laminar drag force is about half of turbulent drag force. Laminar flow over
a platoon cannot be expected due to the boundary layer disturbance between
vehicles in the platoon; therefore the sum of drag of a platoon will always
be greater than the same number of vehicles individually optimized for the
lowest individual aero drag.
In short, platooning PRT vehicles offers negative benefit to cost ratio
compared with vehicles aerodynamically optimized individually.
Daryl Oster
http://www.twitt.org/BIRDS.htm
And other researchers have shown that the aerodynamic advantage of v
formation of birds is due to increased lift efficiency rather than reduced
parasite drag -- the angle of the v is much wider than would produce
parasite drag reduction, and there is a timed wing flapping interaction that
takes place to maximize the recovery of lift from the tip vortexes. This
reduces the induced drag.
Daryl Oster
(c) 2007 all rights reserved. ETT, et3, MoPod, "space travel on earth"
e-tube, e-tubes, and the logos thereof are trademarks and or service marks
of et3.com Inc. For licensing information contact: POB 1423, Crystal River
FL 34423-1423 (352)257-1310, e...@et3.com , www.et3.com
> -----Original Message-----
> From: transport-...@googlegroups.com [mailto:transport-
> innov...@googlegroups.com] On Behalf Of rot...@zahav.net.il
> Sent: Wednesday, May 09, 2007 4:39 AM
> To: transport-...@googlegroups.com
Bruce A. McHenry
You seem to worry about the 180 mph speed.
I do not understand why 9.3 seconds of a ramp that is 1500 feet long would not fit inside Downtown New York City.
http://en.wikipedia.org/wiki/New_York_City 322 square miles 8 million potential paying customers who cannot get home quickly.
Going faster keeps two cars from sharing the same span and going too slow would really skyrocket costs because it would need to be overbuilt.
The latest project you would be interested in is moving water in the desert with .07 Cd tank cars that are blow molded.
... If we pack them into platoons the guideway structure has to get exponentially more expensive
Daryl Oster
> -----Original Message From: Bruce A. McHenry
> Sent: Thursday, May 10, 2007 5:08 PM
>
> You are right, except for the bit about being expensive. Sure, IT is
> costly to develop but once the logic is worked out, it can be mass
> produced for much less than the fuel savings.
> Otherwise, I don't have an issue with the most of rest of your post
> because it is predicated on the assumption that cars going to the same
> destination must be joined at the origin. From what I understand of the
> underlying physics and the components already under development by OEMs
> (active brake, steering, communication and even accident avoidance), it is
> reasonable to expect that vehicles can be made to hook up and break up
> while moving at freeway speeds.
I do not have a problem with retrofitting existing cars for platooning on a
road (as with the California PATH program) mainly to increase capacity and
secondarily to reduce drag a little, although I consider it far better to
concentrate on individual aerodynamics, and to keep the space between
vehicles at a consistent maximum to minimize the chances of a converge
failure. The objections in my post mainly relate to guideway constrained
PRT, and not road based ITS.
>> For a given capacity; shorter vehicles, in noise to tail platoons,
>> impart far greater loading on a span than longer aerodynamically
>> shaped vehicles operating with consistent spacing. The loading
>> applies to both vertical force and horizontal force of side wind or
>> curve.
> What is your evidence? I expect that even an incomplete elimination of
> frontal and rearward exposed areas would eliminate a larger source of drag
> than a laminar flow along the sides of the vehicles.
Evidence -- simple visualization and elementary calculation:
Consider two systems moving the same amount of vehicles per hour that weigh
one ton. On system #1 with spaced platoons of 10 vehicle of 10 ft length
with 300' spacing between vehicles, and the other system #2 with even
spacing of one vehicle every 40'.
For a 100' guideway span, the system #1 will place 10 tons on a 100' span,
system #2 only 2 tons. A 5:1 difference in span load, resulting in a much
higher structural requirement and higher cost for system #1.
The same applies to wind loading or curve loading on a given span -- the
noise to tail operation will increase the dynamic side load on any given
span, and / or block more wind and thereby react the load to the structure.
In the case of a suspended PRT, with vehicles able to crab into a side wind,
the side load on structure can be reduced even more.
>> More power is required for the lead vehicle, (or lone vehicle) --
>> increasing the power supply requirements to several times greater
than
>> if vehicles of the same capacity were aerodynamically optimized on
an
>> individual basis.
>
> Daryl, if you are saying that the lead vehicle needs a bigger engine, you
> are correct if the followers are all-electric with small batteries and the
> roadtrain is climbing a mountain. (Please avoid the word 'platoon' -
> vehicles 'platooned' in the misconceived AHS trial which did not even
> attempt to address ramps and intersections - the critical congestion
> areas.) But this is a special situation.
> Most cars on the road today cruise on the highway at 10-20% of max power
> (unless they are going over 75MPH, which they should not). This is an
> engine operating point about 2/3 of max efficiency. My back-of-the-
> envelope calculation says that most of today's cars could tow as many as
> five (engine off) mid-size sedans which add a marginal fuel consumption
> around 100 MPG.
>
> ICEs are already sized about 10X the average need. Putting out 2X or 3X
> as much power to pull 3-5 streamlined followers will not require much
> modification. Of course, we are talking about cruise. Each car could be
> able to attain cruise, dock and climb typical hills using its own juice
> whether hybrid or all-electric. One would obviously choose battery or
> engine size depending on where one drives.
Again, I am not referring to present automobiles, but to an optimized PRT
system designed to minimize transportation cost at a given design speed and
capacity on a given route. The necessity to size the motors larger than
needed results in greater cost and weight for the vehicle that is not
optimized individually for aerodynamic efficiency, but relying on being in
part of a group. As for cars on the road, will the lead vehicle be
compensated for punching a hole in the air for the following vehicles?
Also, consider the electric supply needs -- much more power needed in a
concentrated area for a platoon than space vehicles optimized for minimal
individual aero drag.
>
> Splits could be done but even if they were not, that would not impede
> traffic flow. Shladover cited the most bothersome case: on and off ramps.
> To see why that is not a problem, imagine that roadtrains of length 6 cars
> are already the norm in congested traffic. That means about 6 cars enter
> a ramp in the space formerly required by 2 cars. Capacity is tripled. In
> most places, congestion vanishes until demand picks back up ( e.g.
> commuters notice that the traffic is flowing smoothly and stop getting up
> at 5am). Once that happens, it would be unthinkable to go back to
> independent vehicles.
I am not advocating manually controlled vehicles, only that vehicles be
optimized for the highest aerodynamic efficiency on their own without the
need to rely on the presence of other vehicles to achieve energy efficiency.
The system capacity being the same in either case.
>> Laminar drag force is about half of turbulent drag force. ...
>
> If you are right about this, then I have a lot of backtracking to do! I
> wish I'd taken fluid mechanics so I could be more precise but it seems to
> me that a low Cd reduces turbulent drag sharply (and compromises interior
> volume in ways that would be unacceptable to many buyers, not least of
> transit) but does not prevent transfer of energy into pressure waves at
> both front and back of an individual vehicle. I would be grateful for
> some rules of thumb about the energies involved in the various components
> of drag from anyone with a firm grasp of the theoretics.
Both you and Jerry R apparently misunderstand the term "turbulent flow".
In aerodynamic study there are several flow regimes, it seems you two are
confused with the use of the terms turbulent flow and detached flow -- they
refer to different things. (This is a common misunderstanding.)
Laminar flow refers to flow with no substantial formation of a "boundary
layer" Turbulent flow with an established boundary layer is still smooth
and attached, but there is a relatively thin layer that has velocity
variations across the boundary layer -- this is referred to turbulent flow.
Smoke will NOT show any difference in laminar and turbulent flow. Wool
strings a couple inches long taped to the surface will align with the flow
direction in BOTH laminar and turbulent flow. Buffeting or indication of
separated flow is NOT apparent in turbulent flow. Florescent oil placed on
the aerodynamic surface is used to determine if flow is laminar or
turbulent. If flow is caused to transition from laminar to turbulent, there
will be a significant drag increase, however no separation or flow
instabilities will be evidenced. If flow is further disrupted, it will
again transition to separated flow where the boundary layer becomes unstable
and has large fluctuations in thickness and velocity profile -- buffeting
and smoke introduced into the airflow will be disrupted. In addition, wool
tufts on the surface will point in random directions and not be aligned with
the airflow indicating random eddy currents and chaotic flow (this is
defiantly turbulent conditions -- but is referred to separated flow NOT
turbulent flow).
Laminar flow is supported by: a favorable velocity / pressure gradient(a
function of a precise mathematically derived shape); precise shape tolerance
(no bumps, waviness, roughness, chips or scratches on the surface --
especially near the leading edge); and a Reynolds number in a given range
for the aerodynamic surface.
Once flow across a surface transitions from laminar to turbulent, it will
not transition back (unless the boundary layer is removed through pinholes
or slots in the surface by suction, or acoustically modified).
Surprisingly, in some conditions, fully established turbulent flow is more
resistant to separation than laminar flow.
Yet other flow regimes are: compressible flow, choked flow, shocked flow,
phased flow, pulsed flow, superfluid flow, etc.
>
> While I think ETT for inter-city travel is very sexy (and I'm still young
> and foolish enough to be all in favor of that sort of thing), it seems to
> me that you have not argued this based on evidence.
Apparently you have not paid much attention to ETT or this group the last
several years -- if anyone on this group knows of someone who has derived,
accumulated, and shared more concrete evidence about a transportation system
proposal with this group, please let me know. If you lack evidence on ETT,
I believe most on this forum (and several other forums) would agree that it
is not my fault. If you want to see some evidence on ETT, I suggest you
start by reading the ETT patent document available on www.et3.com.
We (now more than 60 licensees world wide) have accumulated more than 30G of
data that relates to every aspect of ETT, and we can back up every claim
with fact and scientifically valid calculation and data. If I make a
mistake (I do from time to time) I am quick to admit it and correct it. I
hope you take the time to try to find any mistakes that others have missed,
or point out any evidence conflicting with what we claim or present.
Also note that I place full contact data at the bottom of every post I make.
> I know the argument about low Cd design but would like to see the same
> designers come up with effective Cd numbers for trains on the same
> guideway. Jerry Roane and I talked about this two years ago wrt TriTrack
> but, as far as I know, he has not run a sim or done any wind tunnel
> testing. Roane is also very focused on cross town runs (think NYC, not
> Dallas - Ft. Worth) and I think this is also a mistake. The total value
> of a network increases as an exponential function of its size. 180MPH
> only makes that more true.
There is plenty of aerodynamic data available on trains, and their drag
characteristics, the same applies to cars and aircraft in close formation.
Guala Luca
ciao
Luca
Guala Luca
> In the wind tunnel you puff smoke to look for actual evidence of what
you mention. Since I have the advantage of playing in the wind tunnel I
can give first hand observations of smoke flowing over the TriTrack and
guideway combination. I have pictures of some views of the smoke
flowing over the entire body form but since I was there with 6 other
observers and experimenters I did not see any turbulence on the whole
body.
Of course, this being a small scale model it works with an entirely different Reynolds number from the real thing. I doubt you will be able to get laminar flow for a significant length of the full-scale fuse, which may be just as well since a laminar flow boundary layer can be very unstable while a turbulent boundary layer may remain "glued" to the fuse for a long distance.
> As a control we
did observe all these things on the outrigger wheel fenders. I do have
photographs of the turbulence leaving the rear edges of the fender and
outrigger tire. In the testing I removed the outrigger wheels and the
team made more measurements. End results -- the two outrigger tires had
essentially the same drag as the entire car body.
I once asked you if the TriTrack had to be symmetrical: why not have two wheels aligned under the body (but not symmetrical with the fuse) and only one outrigger? I was not joking. I was being serious.
cheers, Luca
Daryl Oster
Daryl Oster
(c) 2007 all rights reserved. ETT, et3, MoPod, "space travel on earth"
e-tube, e-tubes, and the logos thereof are trademarks and or service marks
of et3.com Inc. For licensing information contact: POB 1423, Crystal River
FL 34423-1423 (352)257-1310, e...@et3.com , www.et3.com
> -----Original Message-----
> From: transport-...@googlegroups.com [mailto:transport-
> innov...@googlegroups.com] On Behalf Of Guala Luca
> Sent: Friday, May 11, 2007 4:12 AM
> To: transport-...@googlegroups.com
Jerry Roane
1. Center of gravity would not be in the center.
2. The driver would not have full view of the car's width. The three
wheeled off road toys had to be banned in the US from all the death and
injury as a result of the young drivers not realizing how wide their
vehicles were. They would take the front wheel between trees and the
rear wheels would not fit causing a crash. With the steerable front
wheels out where you can see them you won't at least have this problem.
They are as wide as a Chrysler pick up truck and the rear wheel is the
rear bumper giving a wide long stance for a three wheeler. Soon I will
announce another big deal and in that one I add a wheel just to fit in.
It will be a worthless wheel but the rules trump measurements on occasion.
Another point on the interaction of the guideway -- It is only 14.5
inches wide. On super duty pickup trucks the rear view mirrors are
bigger than that. For some reason if you have a large personal truck
your eyes must get proportionally bigger and need a pair of wider and
taller rear view mirrors. ;-)
Here are the wool threads in the wind tunnel. You will notice the
movement of the thread that trails the wheel. You can see slight
movement of the very last thread on the body that is down on the
stinger. I have seen a lot of Formula One car wind tunnel reports. The
open wheel produces quite a bit of drag and they have tried to figure
out a way to get the tires to be less drag but they usually end up
concluding that they just hang out there and that is the best they can
do. In a rain storm nobody can see because of the spray so they stop
the race. Not an option for those who want to get home from work. What
you are saying about the top of the tire is true and because air drag is
a square of the velocity the top of the tire is big time drag while the
lower portion relative speed is less but the squared term overpowers the
gain the lower half contributes. The fender design needs to hug the
tire (minus mud thickness) and try to find the shape of the smoke as it
flows over the form. The fender is more drag than no fender but it is
more hospitable to the following cars. Frontal area is about all you
can do to reduce drag on the wheels short of retracting them. In the
water tank version we don't have wheels and we slow the mini-tankers to
70 mph. That keeps multiple cars off the shorter spans made for this
weight and brings us down to 2 hp. Easily powered by a battery and
small motor for the 170 mile trip with energy packets delivered along
the way via the battery mule. The reason I do not use electrified
guideway is someone will get killed if I do and the graphite gunk that
will build up would be undesirable. I don't want a big black dust
streak flowing the flow lines down the car body. I guess you could
study the graphite dust deposit for aerodynamics class.
Some of the smoke images show what looks like very chaotic flow. Those
images are where the oil that was on the hot wire got too thick and when
the hot wire was zapped with electric power to burn the oil and produce
smoke it lit the oil of fire and it is burning as it creates the chaotic
flow. The excess oil photos have to be understood as to what was
causing the chaotic flows as the oil burned past the car. By the end of
the day the car was coated with oil and the basement of the WRW
engineering building in the heart of UT Austin was filled with burned
oil smoke. Not very environmentally friendly. ;-)
The concept of using the wind tunnel is all the speculation and all the
vocab words mean nothing. The stinger sends out a precise force
measurement that is data logged in the computer. This was also hand
calibrated against bureau of standards gram weights to make sure the
delicate strain gage was accurate and linear. This wind tunnel was no
cheap setup and occupies the whole basement of the building. The flow
looks tame the the photos but if you stick your hair in the flow it will
give you a new do.
Although the images of the car show a mag wheel with spokes there is a
clear hub cap for aerodynamics. People love their wheels. I can't take
that from them. By adding a clear hubcap I get the look of mags with a
smooth airflow. The main difference is these tires are motorcycle
flat-track tires with a pointed tread and no grooves. (I know
blaspheme) This one in my lap measures 3.065" wide. When we get into
production I will mold my own tire rather than use an already tooled
semi standard tire. I can cut another 1/2 inch width off this design
without changing the road foot print because this one is designed for
hard banked turns will excessive lean of the motorcycle. It is a very
soft rubber compound that makes up some for the lack of width. At 25
mph it will be fine. At 180 it is dangling in air not turning (I know
you were concerned about spinning). In the solar version we retract the
wheels and front axles and then we get the full .07 Cd air drag on the
guideway shape.
Bruce I do contend that building Guideway in the city is cheaper than
signal timing. Show me one city where they have sped up anything
screwing around with light timing. The best you can do is speed one
direction. Every other direction goes back to chaos. If you use
priority vehicles then even the one direction is toasted. Light timing
is an inductive laggy control system. I can see how you could suck up
some of the lag with your approach but it is not a total solution but
something smart folks could do next week if given the authority.
5 guideways move a maximum of 138,461 people per hour. In real life
45,000 per hour in your own personal space 1.3 people per car. New York
City would take 58 hours to evacuate to NJ on only 5 guideways. Since
New York is the city of walkers you won't even need that hey?
Jerry Roane
Michael Weidler
Daryl Oster
> -----Original Message From: Jerry Roane
> The fender is more drag than no fender but it is
> more hospitable to the following cars. Frontal area is about all you
> can do to reduce drag on the wheels short of retracting them.
Jerry,
Fixed gear aircraft greatly benefit from wheel fairings -- slightly
increased frontal area, but reducing total gear drag to less than half.
Guala Luca
Jerry Roane
The tag line from Reuters--
"It just didn't do it very quickly"
We intend to put that cliché on its ear. It is the old warn out line
that reinforces the myth that car's can't be better. They always use
illustrations like this one to reinforce to the public that cars are as
high tech as mankind can get so you might as well go buy one and hope
they figure out a way to produce fission soon. You will notice that all
these cars look amazingly like each other. This is the automotive
fashion that was mentioned earlier. What these slow speed races do
demonstrate is that we can do better. The reporter just negated the
entire effort in one tag line in his mind. Aerodynamics is lost on 15
mph cars as in this race and weight reigns supreme. Sad part is weight
actually is a small component (not zero though) where aero is the
overriding component at speeds that people drive in exurbia and
suburbia. With good aero you can go faster than present cars and still
use a lot less energy and still drive 1.2 (or 1.59 according to the US
DOT) passengers per car. A reporter who is looking for a contrasting
tag line will have to come up with something besides speed, air
pollution or energy efficiency to use. Most likely this same reporter
will say These cars are fast and use no oil but they look funny. He is
sure to come up with a negative because that is the pattern and rhythm
they use on all technical pieces. Even the lifts in tone of the voice
follow a prescribed pattern ending as this one did.
Nice cars though!
Jerry Roane