Laser-generated surface structures create extremely water-repellent metals
Link to Rochester University web page.
Very interesting. I wonder if they tried cooling it and putting it into a wind tunnel and adding moisture? Curving it to an airfoil?
I wonder if they tried cooling it and putting it into a wind tunnel and adding moisture? Curving it to an airfoil?
No, they did nothing of that yet. They are still in a very early stage of their research. In the paper it says that treating a single square inch of metal takes an hour. Also they show all their early results on samples of platinum which is certainly not the first choice of making aeroplanes from 
But it all looks very promising and if it really stands up to the expectations we will get a load of useful products in the future. Like aircraft and cars that need no paint, won’t corrode and never require cleaning. Almost too good to be true!
More importantly – how does this specific surface texturing affect drag, if at all?
More importantly – how does this specific surface texturing affect drag, if at all?
If I understand it correctly, these surface textures are at nanometer scale which is well below the typical surface roughness of usual building materials of aircraft. So if there is a difference in drag, it should rather get lower. What the article does not say either is how the surface reacts to non-water contamination like dust, dirt (e.g. dead insects which are one of the biggest problems of TKS anti-ice systems) and oil/grease. Will a dusty or greasy surface still be able to repel water and ice? How can a dirty/greasy surface be cleaned without damaging the nanostructure in the process?
I don’t believe it will work at all.
The main difference between aircraft wings and a static example is the motion of the water drops or droplets.
On contacting the surface with 100kts or 200kts the impact pattern makes a huge difference.
Same was promised with Lotus Effect Coatings (paint). I did not hear anything from them for a long time as far as aviation is concerned …
How about this patent? : Airplane leading edge de-icing apparatus
(…) A fluid circuit is provided for distributing heat transfer fluid that has been heated to the heat diffuser and includes a counter current heat exchanger for capturing heat energy from the exhaust gases exiting the airplane engine. (…)
Have they actually built this?
It was found back in the 1950s that turboprop engines (which push out plenty of waste heat) didn’t generate enough waste heat for heating leading edges. Only jet engines produced enough heat for that. Piston engines have no chance at all, IMHO.
The jet- and jetprop engines take the bleed air for anti-icing from the compressor stages which reduces the propulsion forces. Q of temperature. One should take the heat somehow from the hot exhaust gases, at least with piston engines (?), that would not reduce the performance.
