11% More MPG With No Engine/Driveability Change
- Thread starter StarHalo
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Marduke
Flashaholic
Another example is the new bicyclist uniforms. Key areas are textured to reduce drag. They didn't do the whole uniform though, as drag would have increased.
BTW, I've never seen another thread bring out so many aerodynamicists and aerospace engineers before. :wave:
BTW, I've never seen another thread bring out so many aerodynamicists and aerospace engineers before. :wave:
Myself,
I stopped watching it when I stopped getting cable. The red head Kari Byron :wave:definitely kept my scientific interest up regardless of the subject or it's treatment. (I will not put "that" imodicon up, I will not put "that" imodicon up........)
No offense, but I'm not sure the graphic presentation of getting more lumens out of a flashlight would garner enough ratings to continue the show. But perhaps they could label it as a public service and support it with a designation as a non profit organization. Meanwhile charging a fair fee to the people with shows that actually make money and people actually watch. Something fair like the equivalent of their total production costs to stay on the air. After all it is the publics airwaves they should pay to use them for other than for "public service.":devil:
StarHalo
Flashaholic
I'm not sure where this comes from; they carefully described wake drag, illustrated it with dimpled vs non-dimpled golf balls, went to a wind tunnel and illustrated large scale non-/dimpled golf balls and a small scale non-/dimpled car model, went to a water tow lab and repeated with the models, assembled the full scale car, did multiple runs with base/clay base/clay dimpled each to generate averages, used a solenoid-controlled separate fuel cell to be weighed, etc..
I'm sure it would be possible to just show all the needed math and computer simulation results then roll credits, the three-minute show is over. But many people wouldn't buy it, they want to see it actually done and to grasp the science. I think the Mythbusters do a fantastic job at that, at least partially evidenced by the fact that no one else has bothered to do an entire dimpled car before..
Right, but could you have predicted a decade ago that the hot thing now would be Honda Civics with giant spoilers and comic-book body panels? Again, hypermilers struggle just for single-digit MPG improvements; returning an added 10%+ from thin air would be very desirable to this growing niche group..
Yeah, style influences many things, and puts to bed many good design ideas. I've always loved Mooney aircraft because they came out with a straight vertical tail even though the "in" and modern thing was a swept tail. The swept vertical of a Cessna 152/172 is less efficient than a non-swept one, but it looked better. Style sells.
And yes, I know the early Cessnas had non-swept verticals.. so don't get on my case about that.:nana:
I think there might be too many variables to compare including the fact that one is a high wing design and the other is a low wing design. While a vertical tail may have been ideal for the Mooney, that design may have proven less efficient on a Skyhawk. Also, I think it all depends on what the design specification is meant to accomplish. Maybe a straight tail would have provided more longitudinal control but at the sacrifice of speed and economy. Obviously fighter aircraft and airliners don't have swept surfaces due to aesthetic reasons. It's a conglomeration of design compromises.
I'm thinking Lux may have just been stating that in general terms, especially in the area of repeatability. Obviously it's just a TV show so they're not going to be able to provide 50 test samples. While I realize that most of their experiments are lacking the full scientific process, it's still entertaining and in most cases close enough for government work, as they say. The dimpled car data variation in this case was large enough that it's conclusively an advantage. Maybe after further tests the percentage could change to 9% or 13% but it's clearly beneficial on a car this size and general shape.
FlashCrazy
Flashlight Enthusiast
On anything less than a couple hundred miles per hour, the straight tail is more efficient. Basically you can get away with less area for same amount of lift (which is what the vertical does, lifts sideways to give a yawing force). The Mooney's tail, consequently, has less area than it would've had to have if it were swept. Less area.. less profile drag. Induced drag may be similar, but that comes into effect mainly during operation of the rudder. Yes, all of this is simplified... I won't get into lift-to-drag ratios, roll-coupling, etc., but on these "slow" and small airplanes (more correctly, at these low Reynolds numbers), a straight tail is more efficient ... high wing, low wing, or whatever. That does bring up the point of induced drag due to a blunt tip at the end, but I'm only talking about a straight leading edge... the rear of the fin is swept forward to keep the tip area small, to reduce vortices. That also keeps the bulk of the area closer to the fuselage to keep roll coupling to a minimum (lowers the mean aerodynamic center of the tail). Anyway.. yes you're right.. certainly there's a multitude of design factors to consider.
I guess that's why I just sell flashlights.
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blasterman
Flashlight Enthusiast
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I've seen some older research on this same principle with aerofoils, except the dimples were much smaller in scale. Same effect I guess.
Wind resistance is the biggest cause of reduced fuel economy with cars at highway speed as I recall. Rather than mess with these type of 'hacks', it would seem simplier to simply reduce the over all size of the car and tire width that would result in a more realistic reduction in the coefficient of drag. That means smaller cars, and hell will freeze over first, at least in the U.S..... until gas hits $10 a gallon.
Wind resistance is the biggest cause of reduced fuel economy with cars at highway speed as I recall. Rather than mess with these type of 'hacks', it would seem simplier to simply reduce the over all size of the car and tire width that would result in a more realistic reduction in the coefficient of drag. That means smaller cars, and hell will freeze over first, at least in the U.S..... until gas hits $10 a gallon.
Interesting stuff! Makes sense though since the Mooney was quicker than other designs with comparable power. I think its main rival at the time was the Comanche which had more power but couldn't fly as fast. My dad used to rent a Mooney 231 when I was a teenager and I remember that plane felt like a real hot rod compared to a 182. Back then there was no air traffic to speak of so you can imagine that we had a lot of low level fun.
R@ndom
Enlightened
Sorta like Man vs Wild. Great fun to watch but take it with a grain of salt.
I'm wondering if that's the same as parasitic drag and induced drag...
But what I REALLY want to know, and apparently it wasn't tested, is how the dimples affected the top speed of the car. That information would tell immediately just how the drag changed with the dimples. Unless there's an RPM limiter or governor, or course.
RocketTomato
Enlightened
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Hmmm, interesting stuff here. Would it be possible to make a virtual tail on the back end of the car using air? More plainly what I mean is, could you use a fan blowing out the back end of a car to help control the wake drag more efficiently? Use air to fight air.
jtr1962
Flashaholic
I don't know about using air in that manner but I do remember reading about a vehicle which blew air though thousands of small holes to help create laminar flow. Laminar flow is really the holy grail of vehicle design. Drag from laminar flow increases in proportion to velocity rather than velocity squared as turbulent flow does. If pure laminar flow can be achieved, the implications are staggering, especially for human-powered vehicles. An HPV with pure laminar flow can in theory achieve speeds well over 100 mph (best speed so far under pure human power was 82.3 mph ).
TorchBoy
Flashlight Enthusiast
That's quite an impressive speed. But why does someone scream? :shrug:
Marduke
Flashaholic
It's a method they are researching to control flow on aircraft. However the downside is it's very heavy and expensive.
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Wattnot
Enlightened
And I used to go out of my way to make sure a car I was looking at had NO hail damage!! HAH! Now I'm going to have to seek them out!! 
alpg88
Flashlight Enthusiast
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lmao, no way i'd drive a car like that, even if it was 33% mpg decrease, no way i'm driving golf ball with windows,
btw, there is a guy who pioneered ram implosion wing concept, basically redirecting air flow, creates low pressure in front of the car, wing looks ugly thou, and only works at 50mph an up, some testers got crazy numbers, some very little, all depends on the shape of the wing (which is basically diy). if mechanics of that redirection is researched, and incorporated into cars body , it would be aws.
btw, there is a guy who pioneered ram implosion wing concept, basically redirecting air flow, creates low pressure in front of the car, wing looks ugly thou, and only works at 50mph an up, some testers got crazy numbers, some very little, all depends on the shape of the wing (which is basically diy). if mechanics of that redirection is researched, and incorporated into cars body , it would be aws.
