Cadet asked me something yesterday

[Dragon 3-2]

Yesterday at my meeting and asked me something that in my entire lifetime of being involved with avaition ( 19 out of 21 years } I had never thought of or considered. Needless to say I couldnt answer him.

So now I am asking all of you guys; What gives an aircraft engine its sound, be it Prop or jet.

[Ned]

I would reply "air," as neither a prop nor a jet can make a sound in a vacuum.

[SarDragon]

All sound comes from changes in air pressure from different vibration sources. For airplanes, we have several different, but related, methods.

Propellor noise is from the cyclic "beating the air into submission" as the prop rotates.

Reciprocating engine noise is mostly from the cyclic release of combustion products through the exhaust valves.

Jet noise has two interconnected sources - turbine noise, imitating a mechanical siren, and exhaust roar, from the high speed combustion products coming out the tailpipe and making huge pressure changes in the process.

All of the above is an extreme simplification, but that's basically what's happening. Anything that vibrates in air will produce a sound. Some sounds are pleasant, like music. Others are offensive, and even harmful, although some loud music falls into the latter category.

[SarDragon]

I would reply "air," as neither a prop nor a jet can make a sound in a vacuum.

Regarding airplanes that is correct.

More broadly, sound can travel through any medium that can be vibrated. Water and bone come to mind as examples of that.

[BuckeyeDEJ]

Does the propeller in the triangle you don't like make a sound?

(dodging tomatoes)

[Dragon 3-2]

thanks for the explanation guys

[davidsinn]

What gives an aircraft engine its sound, be it Prop or jet.

Money. Lots of it.

[Cadet Dan]

+1  :clap:     

[Dragon 3-2]

That was brilliant Capt  :clap:

[davidsinn]

That was brilliant Capt  :clap:

Thank you. The other option was paperwork.

[Dragon 3-2]

CAP = Complete All Paperwork....or Come And Pay lol



the cadet says thank you btw