What Makes Jet Engines Whistle? Options

[Ranger]

Hi Everyone.

I know Engines are bound to make noise but what is it that gives Jet Engines there characteristic Whistle and High Pitched Sound?

I think it happens when you pinch their boobs.

[27driver]

I think it happens when you pinch their boobs.

Dude...nothing can whistle when you pinch their boobs. Do you know how difficult that is? No way...

[Spirit MD-81]

Nothing sounds as good as an MD80 or a DC-9! Whenever I see videos of them, the sound of the engines get stuck in my head, the MD80 and DC-9 are like no other. You can actually hear the engines drop and rise in throttle in those classics during aprroach, and can hear the idle, as well as the many differant tones, and sounds of the engines. That is why I like the MD80 so much-becuse of the great sound. Well, it's 11:28PM, time to hit the sack, good night everyone, and have a good night, good bye!

Ladies & Gentlemen, I hope you enjoyed your flight, thank you for flying A Wake Air, have a good night.

Thought I'de like to make a little joke, my mood is lifted.

[AspiringPilot]

Well correct me if Im wrong but I think the sudden suction of hundreds of pounds of air causes the wind to whistle moving at such sudden speeds.
-Aspiring Pilot

[VSA380]

Does anyone know why the 757 makes that sort of grunting noise on take-off?

Dan

[gatorbuc99]

Does anyone know why the 757 makes that sort of grunting noise on take-off?

Dan

As for why the 757 RR engines make that growling buzzsaw sound, I'm no expert on engines but i would say its a combination of the full nacelle type, the shape and density of the fan blades, how much play there is in them, the number of compressor stages, the bypass ratio. The list could go on, the P&W powered versions sound about 90% identical to C-17's(90% engine similarity). Also the tips of the blades are usually going supersonic but since pressure has a direct influence on the speed of sound its not "breaking" the sound barrier even though the tips may be moving at 800mph. The sound is especially influenced by the chord of the blades and how many there are. The more blades there are the more it sounds like a buzzsaw in general, which is why the GE 110/115B and RR A380 Trents are so quite, that and the fan is massive compared to the core, the wide chord blades dont have to turn as fast to get the same thrust. If they had conventional blades they would have a really loud horrible buzzing sound.

[Magnum]

Here is an interesting video on jet engine operation. Good sound. Watch the graphics on the right side during run.


http://www.rolls-royce.com/education/schoo...ey02/flash.html

[gatorbuc99]

Here is an interesting video on jet engine operation. Good sound. Watch the graphics on the right side during run.
http://www.rolls-royce.com/education/schoo...ey02/flash.html

Nice animation, Magnum, thanks alot for the link...good stuff.

[VSA380]

QUOTE(VSA380 @ Jul 1 2006, 03:03 PM)

Does anyone know why the 757 makes that sort of grunting noise on take-off?

Dan




QUOTE(Mcchord_AFB_Airman @ May 24 2006, 12:17 AM)

As for why the 757 RR engines make that growling buzzsaw sound, I'm no expert on engines but i would say its a combination of the full nacelle type, the shape and density of the fan blades, how much play there is in them, the number of compressor stages, the bypass ratio. The list could go on, the P&W powered versions sound about 90% identical to C-17's(90% engine similarity). Also the tips of the blades are usually going supersonic but since pressure has a direct influence on the speed of sound its not "breaking" the sound barrier even though the tips may be moving at 800mph. The sound is especially influenced by the chord of the blades and how many there are. The more blades there are the more it sounds like a buzzsaw in general, which is why the GE 110/115B and RR A380 Trents are so quite, that and the fan is massive compared to the core, the wide chord blades dont have to turn as fast to get the same thrust. If they had conventional blades they would have a really loud horrible buzzing sound.

ahh sorry must of missed it when i was skim reading it

Dan