NACA cap
De NACA-stroomlijnkap
The NACA hood is a type of aerodynamic hood used to streamline radial engines for use in aircraft and developed by the NACA (National Advisory Committee for Aeronautics) in 1927. It was a major advance in aerodynamic drag reduction. Development and installation costs paid off many times over because of the gains in fuel efficiency that made it possible.
The hood forms a symmetrical, circular wing, unlike the flat wing of wings.
It allows cool air to flow through the engine where it is passed over the hottest parts of the engine, i.e. the cylinders and heads.
In addition, after the air passes through the free-standing cylinders, turbulence is greatly reduced. The sum of all these effects reduces air resistance by as much as 60 percent.
The test conclusions meant that almost every aircraft with a radial engine from 1932 was equipped with this hood.
Source:
https://en.wikipedia.org/wiki/NACA_cowling
The hood forms a symmetrical, circular wing, unlike the flat wing of wings.
It allows cool air to flow through the engine where it is passed over the hottest parts of the engine, i.e. the cylinders and heads.
In addition, after the air passes through the free-standing cylinders, turbulence is greatly reduced. The sum of all these effects reduces air resistance by as much as 60 percent.
The test conclusions meant that almost every aircraft with a radial engine from 1932 was equipped with this hood.
Source:
https://en.wikipedia.org/wiki/NACA_cowling
