Let’s take a break from some of the more depressing subjects out there (eg, labor strife) and talk about something cool. Once again, science has proven its awesomeness with a “nanostructure surface” that can make metals repel ice. This would be huge for aviation in so many ways.
Thanks to the Ideas Market blog over at the Wall Street Journal, I found out about this paper put together with the thrilling name “Liquid-Infused Nanostructured Surfaces with Extreme Anti-Ice and Anti-Frost Performance.” Sounds thrilling, right? Let’s talk more about what it actually means.
Airplanes and ice have a love-hate relationship. Airplanes hate ice, but ice loves cozying up to a wing or a tail and causing all kinds of problems. Airplanes are built in very specific ways to ensure that the wings can provide enough lift for the aircraft at various speeds. When ice builds up on a wing, it disrupts the airflow by altering the shape of the wing surface. Even minor changes can have a major impact on lift. The list of accidents due to ice is very long, but some of the more famous are the Air Florida accident at Washington/National and the American Eagle crash over Roselawn, Indiana.
Icing can be a problem at any stage of flight. Before departure, it’s incredibly critical, and that’s why airplanes will “de-ice” before taking off. Have you ever sat at the gate and all of a sudden seen a nasty liquid being sprayed over the aircraft? That’s deicing fluid. Sometimes, it will happen at the end of the runway right before takeoff. Different airports have different ways of dealing with it and the various conditions will impact how often it needs to happen and where. The fluid is meant to melt any ice that might be on the airplane. There is also an effort to use “anti-icing” to create a temporary barrier to prevent ice from forming again. In severe icing conditions, this may not work for very long. As we saw with the Air Florida accident, waiting too long in bad weather can very easily result in disaster.
In the air, it’s a different story since it’s not very easy to find a way to spray the airplane up there. There are three ways to de-ice in the air. Some airplanes (like the one that crashed in Indiana) use de-icing boots that sit on the leading edge of the wing. They inflate to break the ice and then it blows off in the slipstream. There is also a system that uses “bleed” air, meaning it takes air that is diverted off from the engine. The heat is used to melt the ice. Additionally, there are mechanical heating systems that can heat the wings to melt ice.
All of this is no fun and it’s costly. The deicing systems add weight to the aircraft. The need to deice on the ground snarls traffic and delays aircraft left and right. This doesn’t even address the issue of disposal of the deicing fluid. It’s a real mess. So if there’s a way to prevent ice from forming and have it built into the wing, then there should be a huge market for it.
What is being proposed is the use of what they call “SLIPS” — slippery, liquid-infused porous surfaces. Catchy acronym. But, um, what? Well, a previous study gives a little more light into what this is. You start with a “nanostructure surface,” which is really something very, very tiny with little itty-bitty holes in it. Then you infuse a liquid into the holes that naturally does not mix with water. You’ve all done the experiment as a child putting oil and water together only to see them stay separate, right? It’s that idea. So when water comes into contact with this surface, it will be repelled and ice won’t form.
Yes, the idea is simple and extremely awesome. And apparently, it works in some very cold temperatures. These SLIPS are just applied to metal surfaces, so they don’t require any special type of metal. The potential for something like this is tremendous.
I’m sure we’re still fairly far out from having a workable application, but the idea should have bean counters and ops folks alike salivating.