That's why golf balls have dimples! Now that would be interesting to see, a TB with dimples like a golf ball on the inside.
good point, someone should have thought of this...or maybe they did and found a bad side to it.
Quote:
Originally Posted by dirt bike dave
That is the theory, but I've seen parties with advanced knowledge report that a shiny surface does little if anything to promote air flow.
Basically, there is a 'boundry layer' - a thin area of turbulent air near the surface, and it matters not whether the surface is polished smooth or not.
Bottom line is it may not be worth the trouble to polish.
ever hear of the concorde? did you know that before every flight they would wax the skin of the aircraft with a polish to reduce parasitic drag and to further streamline it? how does that theory tie in there????
also, as a pilot I can tell you on my airplane (Piper PA-22) and a much faster airplane (Mooney M20J) that an aircraft with smoother skin (ie. flush metal rivets vs. rounded rivets) will generally cruise 1-2 knots faster. with a good wax on all smooth surfaces you will see another 3-4 knots. howard hughes puts this into good perspective with his HB-1 Racer. He acheived a world top speed record back in the '30s by elimitating drag by shaving the rivets to create a smooth skin aircraft. also, it may help to note the finish of the aluminum he used to further help eliminate drag.
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Last edited by Raptor05121; 06-26-2009 at 07:44 PM.
From the aove link, mainly talking about intake ports:
"Furthermore, polish is not only unnecessary, it's actually harmful, in two ways. The first concerns the airflow itself. The experience of countless engine builders, plus research by Superflow, Boeing, and various members of the Society of Automotive Engineers, indicate that a smooth surface is not necessarily the slipperiest where air is concerned. Ever notice that an airplane's wings are not shiny smooth, but rough? The rough surface reduces air drag, and the wing glides through the air easier. Olympic bobsled teams stick sandpaper-like skateboard grip tape to the sides of the sled and the tops of their helmets for the same reason. Air tends to get lazy on a smooth surface. It's called the "boundary layer effect," and it refers to the fact that an ultra-smooth surface accumulates air pressure next to it. This pressure is really stagnant air, and it effectively obstructs airflow. A slightly roughened surface eliminates this boundary layer and increases airflow. The second way polish is bad concerns combustion. Intake tracts don't just flow air, remember. They flow an air/fuel mixture, whose behaviour is quite different from plain air. The same lazy air boundaries that constrict a polished port's airflow also make fuel "drop out" of suspension in that air. The mixture then enters the cylinder less thoroughly mixed, and poor combustion and reduced power result. For this reason, most builders glass-bead the port walls instead of polishing them. The slight roughness creates tiny eddy currects which keep fuel droplets suspended in the port airstream. Good combustion is thus ensured."
BTW, I was building models of Concorde and flying with my dad many years before you were born. So, um, yeah I've heard of Concorde.
Perhaps the wax and mirror smooth surfaces have a bigger impact on lift than they have on drag.
And flush rivets vs. non flush - would be interesting to see a side by side comparison with two identical planes, one with flush and one without. Thjere are many other factors that influence top speed and cruise speed besides flush vs. non flush rivets. Frontal area, for example. Those Mooney's are pretty small.
Ever notice that an airplane's wings are not shiny smooth, but rough?
Is the author a pilot and/or designer? 100% of the many, many planes I've flown in or just admired from the ground has wings as smooth as a baby's bottom.
Good research and all, but motorcycles and trucks are apples and coconuts here..
On the Concorde, they wax the body, not going anywhere near the wing. So it has nothing to do with lift.
If you would like to see the comparison, start reading on the Hughes HB-1. It was first built with rivets, and Hughes then told them to shave the rivets. I know movies aren't believeable, but in "The Aviator" released a few years back theres a good scene on it.
And who says Mooneys are small? Sure they might not house us 6'2" pilots very well, but I love 'em!
Last edited by Raptor05121; 06-26-2009 at 09:45 PM.
When I think of Alex working on his truck and from his latest projects, it makes me want to post this:
Alex, engines are complex. I wouldn't be taking your truck's engine apart unless you started out on at least going to the junk yard, and finding a broken 4.2/3.8l v6, and start from there.
well the good news is that when i do a project, i do it with you guys in mind so i can tell you if its worth it or not to put a knife in the electrical socket!!!
anywhos, taking a TB off isnt considered "taking the engine apart". i live 4 miles from a JY and have sources to another V6 as a backup, but luckily i dont need to right now.
and believe me. judging from how bad you miss the 10th gens, ill offer to sell you mine if i ever screw up
Yeah, the inside of a TB and the outside of a plane are more alike.
Sure they are! We should all wax the inside of our intake and exhaust systems because of the similarities to the Concorde!
BTW, are we even sure the wax on the Concorde body had anything to do with speed?
FWIW, these leads were mentioned in my 'motorcycle only' apples to coconut link...
"The experience of countless engine builders, plus research by Superflow, Boeing, and various members of the Society of Automotive Engineers, indicate that a smooth surface is not necessarily the slipperiest"
Last edited by dirt bike dave; 06-27-2009 at 09:22 AM.
Intake tracts don't just flow air, remember. They flow an air/fuel mixture, whose behaviour is quite different from plain air.
Gotta respectfully call you out on that. That was true with carburetors and TBI systems, but not port injection. The fuel is spraying right at the backside of the intake valve, the intake tract is only passing air (and crankcase fumes when the PCV is open) (and exhaust when the EGR is open).
__________________
2003 F150XL 4.2 short cab/bed 4x2 5 speed manual 3.55 LS
all in all
its still going to be a v6.....never a v8
There is only about 20 Hp difference between the 4.2 and the 4.6 anyway
The 4.2 in my Son's 98 is kinda peppy compared to my 97 4.6. But it is because of the exhaust I have on mine, it kinda robbed some power from it.
I love the sound, and don't care to go very fast anyway
all in all
its still going to be a v6.....never a v8
true...but I didn't buy mine. Dad bought it new and handed the title over to me for my graduation present, so I'm not complaining. Its an EXCELLENT first vehicle compared to others (I'm sure) and maybe some years down the road I'll be looking for a SCrew. All in all, this is a great mod-based vehicle.
Thanks Manual, no thread is complete without a ATHF picture....
true...but I didn't buy mine. Dad bought it new and handed the title over to me for my graduation present, so I'm not complaining. Its an EXCELLENT first vehicle compared to others (I'm sure) and maybe some years down the road I'll be looking for a SCrew. All in all, this is a great mod-based vehicle.
Thanks Manual, no thread is complete without a ATHF picture....
Ever since JBMX posted that pic... I loved it ever since... especially for some of the stuff I say/do... haha
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