That was an excellent and well reasoned response.
I stopped watching Mythbusters when I realized they are more interested in having fun and getting ratings than using real science or controlled experiments.
I stopped watching Mythbusters when I realized they are more interested in having fun and getting ratings than using real science or controlled experiments.
Re: No Engine/Driveability Change
Some folks would beg to differ, I can think of a few people I know who would consider that car undriveable.
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'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.Starhalo
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 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.
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.
That was an excellent and well reasoned response.
I stopped watching Mythbusters when I realized they are more interested in having fun and getting ratings than using real science or controlled experiments.
There are two types of aerodynamic (or hydrodynamic) drag: boundary layer (viscous) drag and wake (pressure) drag.
Aerodynamicists already did one better than the Mythbusters several years ago by adding low drag NACA duct shaped protrusions (not ducts) at the back edge of the roof of a car which lowered the drag considerably. They 'trip' the flow into mild turbulance at the rear window controlling the wake. I thought at the time to sell adhesive strips to apply above car rear windows, but realized quickly that the reason they didn't put them on cars at the factory was styling - and they would have been hard to sell in the carefree 80's when I saw them. Maybe now is the time?
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 ).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.
That's quite an impressive speed. But why does someone scream? :shrug:
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.