Simviation Forums

When you sit behind the engine in for example a 757, will you still hear the buzzsaw as when you sit in front?  :-? Thanks!

Simple answer, no...

Compare these with same camera and videographer

http://www.youtube.com/watch?v=XXewTuW0lpU

http://www.youtube.com/watch?v=V30hvar0o_8

737NGs have the same issue.  We once paid to upgrade on AirTran so we could be more comfortable and get some sleep, but it was too loud.

Simple answer, no...

Compare these with same camera and videographer

http://www.youtube.com/watch?v=XXewTuW0lpU

http://www.youtube.com/watch?v=V30hvar0o_8

You cannot compare the two videos. This noise is caused when the engine is at or close to max power setting due to temperature or loading. The vast majority of take offs are reduced power take offs to save engine life. No two aircraft will or are unlikely to choose the same take off power setting for the a fore mentioned reason.

Matt

I just wanted to know because we're flying in December... I'll just find out when we go.

BTW we're sitting right above the engine, not in front or behind. 

Simple answer, no...

Compare these with same camera and videographer

http://www.youtube.com/watch?v=XXewTuW0lpU

http://www.youtube.com/watch?v=V30hvar0o_8

You cannot compare the two videos. This noise is caused when the engine is at or close to max power setting due to temperature or loading. The vast majority of take offs are reduced power take offs to save engine life. No two aircraft will or are unlikely to choose the same take off power setting for the a fore mentioned reason.

Matt

It still proves the point however.  You will always get a Buzzsaw in front of the engine while having a rumble behind, power setting dependent.  Compare virtually any takeoff video of being in front of the wing vs behind and you will get the same results.

Simple answer, no...

Compare these with same camera and videographer

http://www.youtube.com/watch?v=XXewTuW0lpU

http://www.youtube.com/watch?v=V30hvar0o_8

You cannot compare the two videos. This noise is caused when the engine is at or close to max power setting due to temperature or loading. The vast majority of take offs are reduced power take offs to save engine life. No two aircraft will or are unlikely to choose the same take off power setting for the a fore mentioned reason.

Matt

It still proves the point however.

Look at the weather in said videos. It is for the most part sunny and hot. Find a video of a take off on a day when it is cold and wet, you are most likely not to hear this sound.

Um...

http://www.youtube.com/watch?v=knIDhewHxOo

http://www.youtube.com/watch?v=DmCJpQ-rQYc

http://www.youtube.com/watch?v=a5iPQz3GBYw

Look at the weather in said videos. It is for the most part sunny and hot. Find a video of a take off on a day when it is cold and wet, you are most likely not to hear this sound.

Um...

http://www.youtube.com/watch?v=knIDhewHxOo

http://www.youtube.com/watch?v=DmCJpQ-rQYc

http://www.youtube.com/watch?v=a5iPQz3GBYw

I did not say it would not happen. If it does happen it is due to the power setting, that being up near to max power. Due to aircraft weight a reduced power take off will not be used. The reason you do not hear it at the rear of the aircraft is because it is high power intake resonance. It occurs at around 96%. A reduced power take off can go as low as 89%, but is normally around 93-ish%, at that setting you will not (normally) hear it, though humidity can also play a factor.
The correct name for this is "fan loading noise"
The fan of a high-bypass turbofan engine has a relatively high loading. Each blade in the fan is operating at a high lift coefficient. Under these conditions, pressure on the front surface of the fan blade is much lower than the pressure on the rear of the blade. This difference in pressure comes together at the trailing edge of the blade. The difference results in a pressure disturbance. This pressure disturbance is the source of the fan noise and as such is linked to the power setting the crew have selected for a take off run. When I do a "trim run" (max power run up) it can also be heard, but again not always as temperature and humidity also play a factor as does the lack of ram effect.

Matt

Ok... So I should be able to hear it because we're sitting kind of in front of the engine (AAL B763 with GE CF6s). CF6s have a very slight buzzsaw so I've heard... 

[quote]
Ok... So I should be able to hear it because we're sitting kind of in front of the engine (AAL B763 with GE CF6s). CF6s have a very slight buzzsaw so I've heard...

Well, just in the case he uses full throttle...   ::)

[quote]Well, just in the case he uses full throttle...

Well come on... It's not real... 
You don't care about sound restrictions and reduced power takeoffs and crap like that in a virtual game... 

[quote]Well come on... It's not real...