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Old 06-20-2018, 03:25 AM   #1 (permalink)
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Rude Efficiency Comparison Formula

Editing to accumulate comparisons of 'pissed off Francis number' : Looking at door frame decals, owners manual and fueleconomy dot gov. is best, other sources are difficult.

yesterday a pretty woman let me see the data plate on her 2016 Smart ForToo, i hope I remembered them right, so:
(capacity 472/GVWR2723)*(39hwy*7.7gal) = .1733 payload fraction*300 mile range = 52 hmm I like her better than her cars efficiency.

[score 85 city] Stock Honda Insight G1 2001ish, revised EPA stats;
(capacity 400lbs/ GVWR 2325) * (revised city epa 48mpg * tank size 10.4 gal) = payload fraction 17.2% * range 499.2 = city francis number of 85

[score 105.8 hwy]Stock Honda Insight G1 2001ish, revised EPA stats;
(capacity 400lbs/ GVWR 2325) * (revised city epa 60 mpg * tank size 10.4 gal) = payload fraction 17.2% * range 615 = highway francis number of 105.8

[score 133 hwy]above vehicle, Removing spare tire n tools 20lbs, IMA coils to batteries 130lbs, lead acid battery to a123s 20lbs modifies payload fraction to 570/2325= 21.7% with no range credit 615 = 133 francis number

[score 156.56 hypermiler] Unit 02 Natalya
GVWR - capacity= implied Curb Wieght, 2325 - 400 = 1925
Unit 02 Natalya lists curb weight of 1878, 2325 - 1878 = 447 capcity; 447/2325 = 19% payload fraction * (79.26mpg * 10.4) = 19% * 824.3 = francis number of 156.56

[score 46 ?] Tesla model 3, short range small battery pack
5710-4469 = 1241/5710 = .21 X 220 = 46

[score 91?]Lexus 2018 Lexus GS 350
4830-3726 = 1104/4830= .22 x 400 ish = 91

[score 65 ?]Toyota Mirai Hydrogen fuel cell
Payload 4 people etc 860??? / curb weight 4078.5 lbs * epa range 312mi
equals 21% for a francis number of 65

[score 141 ?]Prius stock model ? non plug in
3915-3050 = 865/3915 =.22 x 640 = 141

Prius 2007 modified to plug in modded 'Planetaire'
2921 lbs curb weight listed, oddly less than stock with more batteries, 3915 - 2921 = 1000; 1000/3915 = 25.5 % claiming 191mpg with electrical support, spec says 11.9 gal tank, (a complaint says 7?) = 25.5% * ( 191.1 * 11.9) = 25.5% of a range of 2272.9 = francis number of 579.5 , or my rusty French says his mileage includes stopping for electrical recharges which is time and availability in the desert, efficiency not a fair comparison.

MV-22 Osprey
52,600 lbs - 33,140 lb = 19460 lbs capacity/ 52600 = 36.9 % * range 879 knmi = 324

Boeing_CH-47_Chinook
50,000 lbs - 24,578 lb = 25422 lbs capacity/ 50,000 = 50.8 % * range 400 knmi = 203
in this case I don't know if these numbers are at constant altitude, but at short range and high altitude, vertical lift is a binary issue so payload fraction I hold as more important than range since you can switch to a C130
Lockheed_C-130_Hercules
155,000 lbs - 75,800 lb = 79200 lbs capacity/ 155,000 = 46.4 % * range 2,050 nmi = 953
Some multiplier for cost of vehicle plus say 3 years of average operations would improve the 'Francis Number' but there is not much sanity to war or fancy cars.



older notes:
(payload fraction X range) + burrito heat recovery cogeneration, restated:
((max allowable Gross weight-Net or tare or empty or Curb weight)/max allowable Gross weight) x range = number + (waste heat utility) call it the 'pissed off Francis formula'?
this info should be in owners manual/govt agency, but info online is poor autotk website lists both weight numbers but differing with single numbers else where :
Small RV with hot water heating from engine
???? we should be living in our cars for efficiency??


Last edited by FormulaLosAngeles; 07-25-2018 at 12:08 AM..
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Old 06-20-2018, 02:58 PM   #2 (permalink)
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The most efficient small Combustion engine is at the university of Wisconsin, where gasoline is thrown down the throat of a direct injection diesel with 45% EGR, resulting in low particulate and low emissions avoiding a catalytic convertor or ammonia treatment. This more matches the crude oil refining fractions, and would be a possible fix for all those recalled diesel cars parked in the desert. Engine weight to power is obviously heavier than pure gasoline conventional engines. This rude formula attemps to capture these tradeoffs. Similarly a Tesla is available with heavier battery packs for long range, same trade off.
a recent thread here "Total Power efficiency between a Hybrid and EV? Who wins?" reflects the cradle to grave analysis, although it depends on EPA kw per mile and some complexity. In early 1990 I went to see Paul Macrready talk at the Ontario CA Electric vehicle association, to razz him about my calcs that greater CO etc came from electrics than IC, but the first think he told us was a rough calc that said the samething! which took the wind out of room full of EV zealots, but then the speech move on to details of EV-1 and the mania went on to todays EV mania, Wherein it is complex to know how each additional pound damages efficiency because it depends on the driving cycle, let alone the cradle to grave analysis that might include the concrete CO for the foundation of the wind generator...
This is why I came up with payload fraction times range, it captures tradeoffs and reflects utility. It depends on driving cycle but could be matched to EPA city versus highway or the average of both by fuel tank size. Battery pack utilization versus pack longevity is variable. Definition of empty weight and gross weight is variable too, Tesla has no spare tire, and if you add more brakes and stiffer suspension gross weight allowable can go up until you cannot climb a hill. So maybe a hill steepness for a length of time at max gross should be part of EPA numbers. In anycase it gets too complex for anyone to have enough time to debate the truth, similar to data revisions of employment, inflation, money supply, GAAP accounting. So this rude version had its origin in the MV 22 Osprey versus a plain old helicopter, where the expensive and exotic is sold as better, but is so inefficient that people had to travel on roads and get blown up by IEDs.

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Old 06-20-2018, 03:26 PM   #3 (permalink)
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Cost to 'consumers' in a formula would need capital and operating cost/ versus payload quantity and volume. The above rude formula takes that out by using payload fraction.
The open question of why water injection was not used instead of catalytic convertors does point at 'Rockerfellers et al control science/media/law' and dictated that we would have to burn more fuel, and buy platinum. If effect we are forced to buy at the 'company store' as a kind of disguised shell game of slavery. The CARB approvals do show aftermarket water injection approvals, but only in the sense that test showed they did not make things worse than stock, not in the sense that the catalytic convertor could be removed and the engine leaned out. Water being rapidly heated if frozen, to reduce the warm up cycle is regulatory excuse that might need to be overcome. Attempting to cook on exhaust has been a recent experiment for me and a recent thread here about the new Prius. It does seem to require a custom header that maximizes surface area contact as my water heating and burrito cooking has not gone so well.
Likewise for EV people, building wind generation without a concrete foundation is where subsidies if any should be going instead of subsidizing the EV cars at all of our expense. In effect another case of all of us being forced to buy at the company store shell game. But this is something out of our league here, similarly to arguing about cap and trade being keenly supported by renowned environmentalist moralists Goldman Sachs. The most effective things we can do here is to get CARB approval for vast improvements to cheaply purchased old cars, that would be subversive to the company store, and help people directly.
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Old 06-22-2018, 10:29 PM   #4 (permalink)
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I think I understand "burrito heat recovery cogeneration". What is "pissed off Francis formula"?

Quote:
???? we should be living in our cars for efficiency??
Indubitably.

Not sure what taking the ratio of payload to tare weight achieves. I had a Type II panel van that weighed less than a ton with a 3/4 ton payload, while the Clark Cortez motorhome I once had had a tare weight of 7500lb and a payload of 800lb.

With range — an electric vehicle weighs just as much when exhausted, while a fueled vehicle is lighter by the weight of the fuel.
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Old 06-24-2018, 04:40 AM   #5 (permalink)
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thank you for considering the implications, multiplying payload fraction by range prevents claiming only the good statistics in advertising, and hiding the bad statistics, since it combines all the factors, however rudely and imperfectly. (non propulsive heat recovery utility is not really numerable at this time , but that does not mean we should not exploit that which we cannot measure well). The numbers might show it is better to take the bus, but we knew that, and we don't want to take the bus.
It is meant to be a comparison number we can rapidly collect, and even if not perfectly defined or accurate, it can show gross comparisons of utility which may be so great as to render the need for perfection irrelevant. An 'Acid Ratio' in accounting is similar and refers to previous acid testing of gold purity. If your payload fraction is low, you lose some efficiency, be it from a diesel iron block or scads of batteries etc. If your range is terrible you have either poor utility or poor efficiency. multiply the two and the truth cannot be hidden. The weight and range should in the glove box manual for safety reasons by law and the car can be weighed at low cost.

there was an error in the formula which I edited to this below, ((max allowable Gross weight-Net or tare or empty or Curb weight)/max allowable Gross weight) x range = number + (waste heat utility) = non dimensional number or score. An airplane might have an 'Oswald number' made up by .. Oswald. I'm francis, I'm old enough now, I made up a number, I get to name it the Francis number because I am pissed off about bad design that hides by omitted disclosure, which is the definition of fraud.

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Old 07-06-2018, 05:41 AM   #6 (permalink)
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Freebeard "I had a Type II panel van that weighed less than a ton with a 3/4 ton payload, while the Clark Cortez motorhome I once had had a tare weight of 7500lb and a payload of 800lb." "With range an electric vehicle weighs just as much when exhausted, while a fueled vehicle is lighter by the weight of the fuel. "

It would be interesting to get some stats on these examples. I am collecting more in the first post.
The nomad movement on youtube describes using Sterilite plastic storage and non built in appliances to save wieght and money in DIY RV conversions.

I guess if the EPA milage is tested much less than full allowable gross weight in a heavy hauler, there might be some distortion, but if the Epa is consistant in comparative underloading then not so bad. Yes fuel weight does change, the Brueget range equation accounts for this elegantly in aircraft, but in vehicles it depends on the drive cycle, I don't even know if the GWVR or EPA treats fuel load consistently so for the moment I hope it is on average no big deal.

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