Posted on 05/14/2007 11:59:24 AM PDT by antiRepublicrat
The chopped-off tail is actually better. It is called the “Kamm Effect”. Also, the tail cone on the shuttle helps the flight stability of the 747/shuttle combo.
See:
http://en.wikipedia.org/wiki/Wunibald_Kamm
Even the column heading is screwed-up. Is it backwards?
Toyota Prius: 60 City? 51 Highway ?
Manual transmission, right?
BTTTT
You two need to apply to boeing as GENIUS aircraft designers : flat tails like semitruck rear doors instead of tapered tails like ALL aircraft have had all these years, whoda thunk it! In fact, it was the inventor of the tapered tail dymaxion car(google), Buckminster Fuller, who opined that maybe the only sin is ignorance; willful, deliberate ignorance.
For typical American drivers, diesels make much more sense than gasoline-electric hybrids.
A small, light car with a small diesel engine and a manual transmission can be very efficient.
Thanks for the pic. It looks a bit goofy as an overall aerodynamic form but they had the right idea with the tapered tail. Google DYMAXION CAR, Bucky Fuller(fellow architect)had it right 74 years ago : apply the fish form to cars as well as aircraft. Thus the partial vacuum acting on flat rear surfaces is eliminated with the tapered tail.
In the movie : Flight of the Phoenix, starring Jimmy Stewart, you see the clam shell tapered tail. If it works on a 300 mph aircraft, why not a 70 mph semitruck?
What I envision then is either an inflated balloon or open, stretchable weave parachute that deploys at above 35 mph and then re-collapses onto the back doors below 15 mph, as the semitruck slows to a stop in tight traffic(not a solid clam shell). A long, curved pyramid form.
The 9’x10’frame then swings 270 deg to the side upon loading/unloading, like another rear door. If this boosts mileage from 7 mpg to 10 mpg then at $50,000/yr for diesel fuel, that’s an annual savings of about $15,000. Manufacturing/installing this aerotail would be far less than that.
Lights? Embedded LEDs. Length? Say from 10’ to 20’ to the tip. There’s another variation : TWO balloon “tits” on each rear door that zip together w/magnets : top and bottom furrows like a woman’s nipples pressed together, making the ideal curved pyramid shape at highway speeds.
Anyway, explosive decompression of recollapsing air around the sharp rear edges of semitrucks cost them money from the aerodrag of turbulence/karman vortices/suction. Fish have known this for hundreds of millions of years, these other 2 ****s on this thread don’t understand that...yet....
It was used for delivering beer — we take that series here.
Isn’t Toyota the Mnfr. who measures bhp by stripping the serpentine off the engine? I wonder how many get away with this.
Have you taken fluid mechanics? There are a lot more variables at work than just “a tapered look”. Note that Toyota uses a Kamm design on the Prius and most race cars are “Kamm-ish”. Lots of wind tunnel testing for those.
I have several patents on my work, but I did not work for Boeing. Just IBM and GE. Not a genius yet.
Andy
BSME,1979
That is a lot of tonnage moving down the road on the relative cheap. If I want to smoke the tires and go from 20 to 60 in a blink I can, and the more I lay on it the better the fuel efficiency. I hate it when a slow accelerating vehicle like a Prius gets in my way.
For even more fun, try calculating how much additional time you will spend during a month of commuting at 55mph compared to 70mph. Then take your gas savings and divide by those extra hours to find out how much your free time is worth.
At 1,000 of freeway driving, people will spend an extra 3.5 hours per month driving if they limit themselves to 55mph rather than keeping up with traffic at 70mph. And they will save 5 gallons of gas by getting 25mpg instead of 22.5mpg at the higher speed.
So they are effectively pricing their free time at (5 gal * $3.50 per gal / 3.5 hours) = $5 per hour.
The higher-mileage vehicle means even less money saved due to driving slower, so your time becomes worth even less. Driving a Prius slowly might mean giving away your free time at a rate of $3 an hour.
Also notice none of these numbers are with the AC turned on.
The purpose of a standardized estimate is to allow meaningful comparison of one item to another. Vehicles are tested with the same parameters in order to make it an "apples-to-apples" comparison. With EPA estimates, you can accurately predict that a Honda Civic will get much better fuel economy, all else being equal, than a Hummer H2. You cannot predict that you will get 42 MPG (or whatever it is) just because that's the EPA estimate.
The EPA estimates have always come with a disclaimer which explains that your actual mileage may vary. That's because the EPA has no way of knowing what speed you will drive at, what pressure you will maintain your tires at, what altitude you will drive at, how often you will get your oil changed and your air filter checked, etc. There are lots of variables affecting fuel economy.
Breathless accusations of some kind of eeeeevil conspiracy are for drama queens who have nothing important to do. The EPA estimates were never any such conspiracy, but a standardized estimate meant for a more intelligent and less paranoid public.
The beauty of ultra-cap systems in hybrids is that they can absorb energy much faster than batteries. So where the Prius can only recapture 10% of the acceleration energy using regenerative braking, the Mini QED using ultra-caps can recapture 85% of that energy.
That will take most of the penalty out of fast starts and stops.
Cross winds were a problem, as he was towing it behind a Winnebago. This was duly reported to Toyota, who used it to figure average Prius MPG.
I used to have a rule of thumb that I could set the cruise and drive 9mph over the limit with impunity as long as I was not standing out in the crowd, i.e., passing everything in sight. Now I tend to judge more by the traffic flow than the speedometer.
In this case, the comparison to regular cars was flawed, the hybrid mileage highly inflated, which would lead people to buy hybrids instead of regular cars based on false information. It also gave people unreasonable expectations of fuel savings that they hoped would more than pay for the extra price of the hybrid. If the sticker says the hybrid gets 20 mpg more than the regular car and it really only gets 5 mpg more (regardless of what the driver actually gets in either, it's relative), you're screwing a lot of people.
Breathless accusations of some kind of eeeeevil conspiracy are for drama queens who have nothing important to do.
There's no conspiracy, just growing pains in dealing with hybrids.
You're right. My comments were aimed at the general population of people who generally moan about EPA estimates being inaccurate.
In this case, their testing methodology simply doesn't work well. Also, I'm mystified by the EPA's decision to base fuel economy estimates on emissions data, rather than a simple measure of fuel flow rates. Why not just measure what you're measuring directly?
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