This article and thread has got some major Tai’s Model vibes [1]
A fundamental principle of aeronautical engineering has been overturned
41–50 of 143 posts
Re: A fundamental principle of aeronautical engineering has been overturned
#42Earlier quoted context omitted.
> "...like Formula 1" Or projectiles like bullets and missiles. A sniper bullet with nanoscale textured surface that's able to go x% farther due to reduced drag seems plausible.
On a metal as soft as copper I imagine that texture'll last about 30 minutes after it's issued to the soldier.
Once the box magazine is loaded, it's not like the individual cartridges are being handled heavily.
Deer season involves a lot of loading and unloading a rifle (for those of use without removable magazines who are also bad at finding deer), and the bullets don't come out of it appreciably worse for wear. And that's for lead-free soft annealed copper ammunition. If you aren't being aggressively careless with your ammunition, it's not getting a lot of friction and scratches.
Re: A fundamental principle of aeronautical engineering has been overturned
#43Any competitive sailor or foil-racer knows that the underwater surface has the least friction and best laminar flow when sanded with fine-grid sandpaper, around 1000 to 1500 grid. It always surprised me that this was not true in air and airplane wings were supposedly best when glossy. So now it turns out that this is indeed not true, and airfoils also benefit from micro-roughness for lowest friction. Now the surprisi…
I wonder how quickly airlines will adopt sanded/rough wings. It's also interesting that the efficiency of winglets were known for quite awhile but only somewhat recently have nearly all airliners adopted them.
Re: A fundamental principle of aeronautical engineering has been overturned
#44Klaus Savier is a longtime efficiency experimentalist, and opted for unpolished paint circa ~1990. His initial goal was weight reduction but numbers showed the finish had aerodynamic benefits.
I'm intrigued by the methodology of the wind tunnel: using magnets to more precisely measure and to avoid interference from guy wires...
Re: A fundamental principle of aeronautical engineering has been overturned
#45This reminds me of the Dimple Car Experiment from Mythbusters.
Re: A fundamental principle of aeronautical engineering has been overturned
#46If the application method is as rudimentary as sandblasting, it sounds rather simple to retrofit to existing aircraft. If it works as they state it does, it's a virtually free same-day fuel efficiency boost. However, I did not see what the actual net improvement was. When they talk percentages, they are talking only about "in the transition zone". They say the coefficient improves throughout, but in theory, it could…
What I've seen is a more structured texture applied with plastic films. https://www.lufthansa-technik.com/en/aeroshark One company claims up to 4% less fuel use. https://mako.aero/insights/delta-partners-with-mako-to-test-...
They allude to this alternative tech in the article, and I think it will stay the dominant approach because the far finer dimensions of the new tech talked about in the article, even if integrated into a film using glass beads as they also did, appears to be intrinsically much more susceptible to rapid functional degradation. It's about or less than the thickness of dirt / grime / bug goo. But tests will tell.
Re: A fundamental principle of aeronautical engineering has been overturned
#47If the application method is as rudimentary as sandblasting, it sounds rather simple to retrofit to existing aircraft. If it works as they state it does, it's a virtually free same-day fuel efficiency boost. However, I did not see what the actual net improvement was. When they talk percentages, they are talking only about "in the transition zone". They say the coefficient improves throughout, but in theory, it could…
Paint and finish on an airplane has to account for a lot more than aerodynamics. So you need to build it from the ground up as that coating could be the difference between the surviving daily temperature fluctuation for 10000 trip vs 1000 trips
Re: A fundamental principle of aeronautical engineering has been overturned
#48Golf balls.
Re: A fundamental principle of aeronautical engineering has been overturned
#49Any competitive sailor or foil-racer knows that the underwater surface has the least friction and best laminar flow when sanded with fine-grid sandpaper, around 1000 to 1500 grid. It always surprised me that this was not true in air and airplane wings were supposedly best when glossy. So now it turns out that this is indeed not true, and airfoils also benefit from micro-roughness for lowest friction. Now the surprisi…
I wonder how quickly airlines will adopt sanded/rough wings. It's also interesting that the efficiency of winglets were known for quite awhile but only somewhat recently have nearly all airliners adopted them.
It’s probably operationally easier to keep surfaces smooth than to keep them a specific amount of roughness.
Re: A fundamental principle of aeronautical engineering has been overturned
#50Earlier quoted context omitted.
I wonder how quickly airlines will adopt sanded/rough wings. It's also interesting that the efficiency of winglets were known for quite awhile but only somewhat recently have nearly all airliners adopted them.
It’s probably operationally easier to keep surfaces smooth than to keep them a specific amount of roughness.
yeah. what are the effects of too much roughness? may be safer and easier to maintain at smooth than at a specific roughness spec