Peter wrote:
Why doesn’t everybody use fuel injection?
Gravity feed to a single carb is about the simplest and least troublesome fuel system that exists and with it the engine also starts immediately every time, even with the no battery Armstrong Method when necessary. The slightly higher fuel burn is a non-issue to me by comparison, about $4/hr or say $200/year for my usage to have a simpler, easier to maintain engine.
My current plane has two fuel pumps, I’d surely prefer none.
Why doesn’t everybody use fuel injection?
The bowl is not a necessity for a carburetor though, in fact it is useless when trying to fly upside down. It’s only there to mitigate variations due to varying supply pressure of fuel. Small “household” engines typically use a diaphragm carburetor, which is a compact, combined pump and metering system and has no need for a bowl, and works in all directions. Then there is the simple ventury/needle carburetors used in RC and also in some large airplanes, notably Ellison and Rotec. They call it “throttle body injectors”, probably because it sounds way cooler than “carburetor” They are still carburetors though, only without the bowl.
The basic principle is the same in all. A venturi with high velocity, lower than ambient pressure air sucks out fuel and breaks it up into tiny droplets. This is captured exceptionally well in that video. One can literally see the large droplets “explode” into a mist.
Our ground school teacher having Aircraft General Knowledge has said he’ll use (parts of) that video in the next course.
Slightly long winded, but pretty cool
Been around all kind of engines since an early age (whatever that means…), and never realized to the full that the air basically stops in the throat, probably less so on a multi-cylinder at hi revs.
Good find!
This channel can steal a life, it’s so good!
Very cool. Weber in action.
Some amazing high-speed footage in this one. They make a transparent version allowing you to see the whole sequence.