A ridiculous (and probably a nonsense) question

[Mister_Penetrator]

I am sure nobody has ever asked this kind of question here before, but is it possible to convert a jet engine (from boeing 707, 727, 737, or etc.) into a siren (such as by replacing the the flight rotors with the rotors of a siren)? I know there are probably going to be some of you guys laughing your heads off at this question, but I just thought I would ask and see what the responses are.

[Midwest Siren]

well at the speeds the rotor would rotate it would be like 1100 htz and that would be way too high pitched.

[Nelso90]

A jet engine is already a siren. It has rotor blades going right across stator blades. In fact, the effect is so great, manufacturers have made serrated fan blades to try and counteract the effect. I would know, not only does my Dad work for the airlines, but those damn planes come over like every 2 seconds!
Here are those fan blades I was talking about.

[SoundOff]

The axial flow compressor might give a "chopper" effect if you think of the stator and rotor blades arrangement.

Look very closely at the animation

[Travis]

As Nelso already stated, turbofan engines are already sirens. If you ask me, the CFM's most closely resemble sirens, as the harmonics of that particular engine used on the Airbus A318/319 "sing."

[cdvtripleseven]

Why would a jet engine need to be a siren.
The things are loud enough as they are.

[Elliott]

A jet engine is already a siren. It has rotor blades going right across stator blades. In fact, the effect is so great, manufacturers have made serrated fan blades to try and counteract the effect. I would know, not only does my Dad work for the airlines, but those damn planes come over like every 2 seconds!
Here are those fan blades I was talking about.

The idea has crossed my mind as well. I have been working on the GEnx Engine (FETT)which basically has the same size fan as the GE90. That size engine is usually on the Airbus to my knowledge, and I dont even want to imagine the noise of a low-alt flyby. But man, imagine slots on the fan case!

[SirenMadness]

Airbus? I thought that they use the quietest engines possible to obtain by their budget. To my knowledge, high-bypass engines are not that loud, especially if they are a modern product by GE!

[Travis]

High bypass fans are quieter and more powerful. And the CFM engines that Airbus uses are very quiet...but you can still feel them quite well in the cabin. Jkvernon will be posting my example video here in a few seconds. It isnt the complete version, just enough to let you hear those whiny engines of the A318. They sound great on startup as well as spool up. Once up to takeoff power they aren't that great sounding, but they are quiet! Even in the rear of the cabin where I was sitting. They are considerably more quiet than the CFM version used on the 737-300's+ I've been on. (They dont just rattle and roar like the 73's do)

http://www.youtube.com/watch?v=-1vzYhgo5_g

[Nelso90]

I did not know the 318 used CFM engines. I thought they were PW6000's. Anyways, those things are quiet! On the 319's and 320's, the 56 series engines sound the same during taxi as the video, but then that whine turns into a piercing scream as N1 and N2 come up to speed, then it really gets noisy as C1 spools up a few seconds later. When C1 kicks in, you really start to feel the push. It's almost like really bad turbo lag. But the noise from C1 isn't the siren effect, it's actually small sonic booms coming off of the blade tips.