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Car Forum / Mazda / Mazda Miata / May 2008CW values for the NC
I've been reading an article on cars and their CW values and what it means for efficiency. The article is in German but I thought the figures given for the MX-5 may be interesting so here it goes. Top down: 0.45 cw Soft top up: 0.39 cw Hard top up: 0.37 cw At 150 KMPH The Hard top uses 0.3 litres of gas less than the soft top per 100 KM. With the top down 1.4 litre extra gas is used per 100 KM (also at 150 KMPH). This can of course also be translated to possible top speeds but the article does not do that - it only comments that no one drives top down at more than 150 KMPH (Sort of making me "no one" as I do - it's loud but otherwise fine). http://www.autobild.de/artikel/autos-im-windkanal_666465.html http://www.autobild.de/mmg/mm_bildergalerie_668619.html?tab=0&page=15&bid=0&m=&e=&i= http://www.autobild.de/mmg/mm_bildergalerie_668619.html?tab=0&page=16&bid=0&m=&e=&i= http://www.autobild.de/mmg/mm_bildergalerie_668619.html?tab=0&page=17&bid=0&m=&e=&i= No real surprise that the soft top is a little less smooth or that top down is even worse when it comes to smooth airflow. Here are some other figures (also from the article): The ten most efficient 1. BMW 5er 0,26 1. Mercedes S-Klasse 0,26 1. Lexus LS 460 0,26 1. Toyota Prius 0,26 2. Audi A4 0,27 2. BMW 3er 0,27 2. Mercedes E-Klasse 0,27 2. Mercedes C-Klasse 0,27 2. Mercedes CL 0,27 2. Porsche 911 0,27 And the ten less efficient 1. F1 Race car 1,2 2. 2 Mercedes Actros 0,81 3. 3 Morgan Roadster 0,6 4. 4 Land Rover Defender 0,59 5. 5 Hummer H2 0,53 6. 6 Mercedes G-Modell 0,52 7. 7 Morgan Aero 8 0,51 8. 8 Jeep Wrangler 0,49 9. 9 Jeep Commander 0,41 10. 10 Chrysler PT Cruiser 0,38 Kind regards Bruno Biggest Irony in all of that is the model name of one of the cars on the 'worst' list; Morgan Aero 8! That's pretty funny. Biggest surprise was the F1 car. That just does not jive with common sense and logic. Seems to me that they have horribly tiny frontal areas and there's no flat / blunt surfaces. Maybe I just figured it out; the ground effects intentionally abut a whole bunch of air, with the resulting force of that air pushing the car downward in order to keep the car on the ground. Hmmmmmmm, I could be right!?! In effect these cars need the huge HP to utilize the air to keep them stuck down! Can you imagine how fast these buggers would be with aero aids that allow them to slice thru the wind? Chris 99BBB > Biggest surprise was the F1 car. That just does not jive with common sense > and logic. Seems to me that they have horribly tiny frontal areas and [quoted text clipped - 7 lines] > Chris > 99BBB The aerodynamics on the F1 cars produce so much down force that the Indy cars can theoretically be driven upside-down as long as you keep the speed above 81 mph, since roughly 81 mph is when the down force equals the weight of the car. They produce roughly 2 times their weight in down force once they hit 118 mph. From Wikipedia: The cars' aerodynamics are designed to provide maximum downforce with a minimum of drag; every part of the bodywork is designed with this aim in mind. Like most open wheeler cars they feature large front and rear aerofoils, but they are far more developed than American open wheel racers, which depend more on suspension tuning; for instance, the nose is raised above the centre of the front aerofoil, allowing its entire width to provide downforce. The front and rear wings are highly sculpted and extremely fine 'tuned', along with the rest of the body such as the turning vanes beneath the nose, bargeboards, sidepods, underbody, and the rear diffuser. They also feature aerodynamic appendages that direct the airflow. Such an extreme level of aerodynamic development means that an F1 car produces much more downforce than any other open-wheel formula; for example the Indycars produce downforce equal to their weight at 190 km/h (118 mph), while an F1 car achieves the same downforce:weight ratio of 1:1 at 125 km/h (78 mph) to 130 km/h (81 mph), and at 190 km/h (118 mph) the ratio is roughly 2:1. Therefore, theoretically, F1 cars can drive upside down from 130 km/h (81 mph). Keeping it on topic, can you imagine how the Miata would drive with that kind of down force? You would obviously need a lot more power to drive your car that starts to "weigh" well over 4000 pounds at highway speed. Cornering would be even more fun than ever! :-) Pat Why doesn't someone do that? Drive an F1 car upside down! That could get a crowd excited! Chris 99BBB >> Biggest surprise was the F1 car. That just does not jive with common >> sense and logic. Seems to me that they have horribly tiny frontal areas [quoted text clipped - 43 lines] > > Pat > Why doesn't someone do that? Drive an F1 car upside down! That could get a > crowd excited! > > Chris > 99BBB I wondered that myself. It would require either being able to smoothly climb a wall and onto the ceiling at over 81mph, which could be tricky or even impossible. (Leon?) The other possibility that I see is to have the car hooked onto the ceiling with a mechanism of some sort that releases once enough speed has been attained. That would require building a ceiling that will work as well as a road, assuming that one does not already exist. I would want to see the second option tested without a driver first, though a short and straight drop onto the roof at 90 mph or so might not be nearly as bad as some of the wrecks that occur during racing at much higher speeds. Losing a F1 car in an experiment would not be the greatest thing, but various people spend millions of dollars on silly things every day. Pat > I wondered that myself. It would require either being able to smoothly > climb a wall and onto the ceiling at over 81mph, which could be tricky > or even impossible. (Leon?) How about an oval track, only vertical? Shoot down the straight to build up speed, enter a vertical curve at the end which continues until you're upside down and headed back the other direction. Vertical curve at the other end takes you back to the ground on the original straight. That would be a hoot to watch. They could build the grandstand in the middle. miker > How about an oval track, only vertical? Shoot down the straight to build up > speed, enter a vertical curve at the end which continues until you're upside > down and headed back the other direction. Vertical curve at the other end > takes you back to the ground on the original straight. That would be a hoot > to watch. That would be very cool. I am no expert at physics, but is seems like the cars should be able to do it given a properly designed, and probably very expensive track. Not sure the drivers would approve. They could build the grandstand in the middle. > miker That would make wrecks far more interesting when they occurred top-side. As the cars either dropped below speed or lost enough body panels, down from the ceiling they would come, raining flaming fuel and debris on the crowd. After my one and only trip to the Indy 500, I am not completely against the idea. (I am glad that I went, BTW, once) It would make the event quite a bit more interesting to me and I don't think that I would ever miss a race on television. ;-) Pat >> How about an oval track, only vertical? Shoot down the straight to build up >> speed, enter a vertical curve at the end which continues until you're upside [quoted text clipped - 3 lines] > > That would be very cool. Not as cool as a m?bius strip racetrack...  SignatureGrant Edwards grante Yow! Why are these athletic at shoe salesmen following visi.com me?? >>> How about an oval track, only vertical? Shoot down the straight to build up >>> speed, enter a vertical curve at the end which continues until you're upside [quoted text clipped - 4 lines] > > Not as cool as a möbius strip racetrack... If someone is going to try it with a F1 car they had better do it quick. I believe regs are going to reduce downforce considerably in 2009. It would need a strong ceiling. The downforce used at some tracks is huge. >>>> How about an oval track, only vertical? Shoot down the straight to build up >>>> speed, enter a vertical curve at the end which continues until you're upside [quoted text clipped - 8 lines] > I believe regs are going to reduce downforce considerably in 2009. > It would need a strong ceiling. The downforce used at some tracks is huge. That's where the moebius strip track has an advantage: once the field is spread out enough, you'll have cars on both sides of the strip and the downforces would cancel. Perhaps the staring lineup could be split so that half the cars start on one side and half on the other. SignatureGrant Edwards grante Yow! I've got an IDEA!! at Why don't I STARE at you visi.com so HARD, you forget your SOCIAL SECURITY NUMBER!! > That's where the moebius strip track has an advantage: once the > field is spread out enough, you'll have cars on both sides of > the strip and the downforces would cancel. Perhaps the staring > lineup could be split so that half the cars start on one side > and half on the other. To continue this silly thread.... I have to admit to forgetting what a moebuis strip is, thank you for the reminder. Like to keep that vocabulary thing growing, and that is one of the few things with a name that does not have at least 15 definitions in the English language depending on the context, so I should be able to remember it. How about a Figure 8 Klein Bottle track? ;-) http://en.wikipedia.org/wiki/Image:KleinBottle-Figure8-01.png Pat <snip> >How about a Figure 8 Klein Bottle track? ;-) > >http://en.wikipedia.org/wiki/Image:KleinBottle-Figure8-01.png Well, if you like topology, you can get your own Klein bottle. I have one, though it's not big enough to race on. See http://www.kleinbottle.com/. The problem with math jokes is that most folks don't get them. Jim - sometime mathematician, sometime programmer > See > http://www.kleinbottle.com/. Priceless! Thanks. > The problem with math jokes is that most > folks don't get them. It's the same with classical music jokes (q.v., PDQ Bach's "Concerto for Horn and Hardart" et al.). SignatureLanny Chambers St. Louis, MO '94C > It's the same with classical music jokes (q.v., PDQ Bach's > "Concerto for Horn and Hardart" et al.). That's more of a food joke and one that people should get Automat- ically.... <Ouch!> SignatureXS11E, Killing all posts from Google Groups The Usenet Improvement Project: http://improve-usenet.org > > It's the same with classical music jokes (q.v., PDQ Bach's > > "Concerto for Horn and Hardart" et al.). > > That's more of a food joke and one that people should get Automat- > ically.... <Ouch!> Food joke, NYC joke, whatever. I had the dubious pleasure of "dining" at H&H years before the first PDQ album came out in 1965 (and promptly blew me away, music geek that I am). As a solo instrument, the hardart is a large console with divers objects on top that are struck, plucked, blown into or otherwise abused to produce a chromatic scale. There are also some balloons and a shotgun. The mallets, etc., are obtained by inserting coins that open doors to their compartments. Voilà, the parody is complete. The best part about PDQ Bach is the imaginative titles: Iphigenia in Brooklyn, Royal Firewater Musick, Pervertimento, Serenude, Sonata for Viola/Four Hands, Toot Suite, Fanfare for the Common Cold, and the operas Einstein on the Fritz and The Abduction of Figaro. If you're not a music geek, though, best just go back to your iPod. SignatureLanny Chambers St. Louis, MO '94C And we all here should appreciate "The Stoned Guest", the half-act opera by PDQ Bach which included the off-coloratura "Carmen Ghia". My favorite is "New Horizons in Music Appreciation" (And they're off.....) SignatureKen Lyons '97 Brilliant Black/'90 Classic Red Inside the Beltway >> > It's the same with classical music jokes (q.v., PDQ Bach's >> > "Concerto for Horn and Hardart" et al.). [quoted text clipped - 18 lines] > > If you're not a music geek, though, best just go back to your iPod. > And we all here should appreciate "The Stoned Guest", the half-act opera by > PDQ Bach which included the off-coloratura "Carmen Ghia". My favorite is > "New Horizons in Music Appreciation" (And they're off.....) One of my favorites, Bobby Corno and all! The early Vanguard albums were generally funnier IMHO, though I love the 1712 Overture on Telarc. If you haven't seen a PDQ concert in person, add it to your list of musicological things to do. SignatureLanny Chambers St. Louis, MO '94C >> That's where the moebius strip track has an advantage: once the >> field is spread out enough, you'll have cars on both sides of [quoted text clipped - 13 lines] > > How about a Figure 8 Klein Bottle track? ;-) I've always wanted a Klein bottle. SignatureGrant Edwards grante Yow! ! Up ahead! It's a at DONUT HUT!! visi.com |
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