Its interesting to me that at cruise engine settings...you are in the correct RPM range to create the buzzsaw sound, but you can no longer hear it. Throughout the cruise the engines will still be going 'grrrrrrrr'. You can notice it especially on a 757 during cruise, you can't really hear it anymore...Jump to post
Thats what I'm getting at. Chevrons on the 787 was a surprising example of prioritising noise suppression over fuel consumption. That case is especially strange considering the engines were probably also within current noise regulations without the chevrons.... And although yes it is correct to say ...Jump to post
And...if we were to come up with some new technology that boosted fuel effiency by 20% but took us back to pre hush kit 727 sound levels (acceptable in the 70’s apparantly), would we ease noise regulations to accomodate it?
My question is long winded but hopefully you can see where im going!
Hi I was looking into unducted fans the other day and it got me thinking... Where is the line drawn between increased fuel efficiency and noise? Fuel efficiency is obviously crucial, and in an age where were spending tens of millions in R&D to eak out a 5% advantage...is a subsequent 10% increas...Jump to post
Here goes: Forgetting tire limits and runway length, what do we reckon would be the maximum speed of a commercial turbofan powered plane on the runway if it was to never liftoff? I randomly wandered this the other day, did a google search but to no avail. There must be a maximum speed at which engin...Jump to post
Interesting, thank you for the replies! So aquaplaning/hydroplaning DOES happen occasionally. It seems like if an aircraft were to start sliding to one side I can't imagine the nosewheel steering having enough authority to correct. I've searched youtube hoping for some examples but haven't found any...Jump to post
What stops planes from aquaplaning in wet conditions? I know that the rudder can minimise this above a certain speed and add stability, but I am surprised it doesn't seem to happen more often. Aircraft tires seem remarkably simple (in comparison to automotive tires). Am i missing something?
Yep, 'Combustor Howl', caused by combustion instability. Same thing that causes that bassy sound during startup when the igniters are switched on. Shame we won't hear it anymore: the noise stems from a less than perfect combustion regime. See here for full paper (Paywalled). http://proceedings.asmed...Jump to post
Yes Masi1157 Thanks for the relevant interesting reply! I always thought it sounded like a 'resonant' type of sound. However I didn't think 'resonant' sounds would pitch up and down in a chamber with a fixed geometry, ie a jet engine combustion chamber, but rather have a fixed note that fades in and...Jump to post
Actually that's not true at all. All sound is generated by some type of physical process, we can actually 'predict' what type of sounds certain processes will generate. There is a whole field dedicated to researching this, and its useful. The way my voice sounds is a result of the complex interplay ...Jump to post
Hi All I've noticed that all Trent engines make a distinctive 'wooing' noise under certain circumstances. The sound only occurs whilst advancing throttles through the lower rpm range and will stop as soon as throttles are left static, it never occurs whilst retarding throttles through the same rpm r...Jump to post
Feels good to finally join after a decade+ of observation!
My question is...how likely is it that GE will attempt to beat the GE90 thrust record any time soon? Could a test GE9X be 'turned up to 11' and put out a few 1000lbs extra...just for bragging rights of course!