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-   -   What do I not know? (https://www.pprune.org/jet-blast/563669-what-do-i-not-know.html)

carlrsymington 28th Jun 2015 01:19

What do I not know?
 
There is plenty I do know,but if it could be weighed it would a lot less than the weight of what I don't know.
On this basis, I would love to know why every airliner is not being modified to have serrated edges at the exit of their engines.
I don't understand what they do but why has everyone not got out the tin snips?
I understand winglets & the cost ($ ? 300k) v return.
Is there no fuel saving? just noise reduction?

ChrisVJ 28th Jun 2015 01:33

According to some stuff I saw the edges were a attempt to modify or diminish noise but turned out not to be effective, certainly not effective enough for the extra expense.

megan 28th Jun 2015 05:48

What Boeing has to say

Boeing Frontiers Online

Patent

http://patentimages.storage.googleap...0030213227.pdf

Espada III 28th Jun 2015 07:28

I was under the flight path into MAN last week at a sports day and by far the noisiest planes were 737s, mainly but not exclusively from Ryanair. We were no more than one mile from the threshold. Airbus machines were noticeably quieter and the quality of the noise was better also. Far less whiny.

Wingswinger 28th Jun 2015 07:36

I'm sorry but a jet engine's not a jet engine unless it leaves a reheat plum the length of the aircraft and air-ripping, thorax-vibrating noise behind it. Airline engines are girly.

Flightmech 28th Jun 2015 10:12

What do I not know?
 
I agree. At the very least we should go back to 707s with unhushkitted JT3s or 1-11s with water-injected Speys. Smoke on...go. Proper noise :-)

Tankertrashnav 28th Jun 2015 10:29

The VC10 was surely the best example. Inside the cabin one of the quietest aircraft you could fly in, whereas on take off everybody on the ground within 10 miles was having their fillings loosened!

(edited at 1035 - snap dixi!)

dixi188 28th Jun 2015 10:30

And the VC-10

west lakes 28th Jun 2015 10:56

Huh
The four RR Olympus engines of a Vulcan as it does a vertical climb over Manchester airport!
Not much to beat that

om15 28th Jun 2015 11:15

Sixteen RR Olympus on four Vulcans departing Akrotiri on a hot day, two going high and two staying low, most amazing sound ever.
A stream of Lighnings in reheat was also pretty enjoyable.

Kitbag 28th Jun 2015 11:16


The four RR Olympus engines of a Vulcan as it does a vertical climb over Manchester airport!
Not much to beat that
Except perhaps the four reheated RR Olympus of Concorde?

VP959 28th Jun 2015 12:35


Sixteen RR Olympus on four Vulcans departing Akrotiri on a hot day, two going high and two staying low, most amazing sound ever.
A stream of Lightnings in reheat was also pretty enjoyable.
Reminiscent of hot days stuck down at Gata popping out of the cabin to look up at the purple glow from Lightnings going vertical over our heads. Somehow the noise of a Lightning always seemed more earth-shaking to me than that of the Vulcans, something to do with them rotating to near-vertical on departure I think.

racedo 28th Jun 2015 12:49

Nimrod departing Gatwick in Summer 2003...................earth shook.

ehwatezedoing 28th Jun 2015 15:51

Apparently Saturn V's lift off were quite something! :eek:

con-pilot 28th Jun 2015 16:15


Originally Posted by Wingswinger (Post 9026907)
I'm sorry but a jet engine's not a jet engine unless it leaves a reheat plum the length of the aircraft and air-ripping, thorax-vibrating noise behind it. Airline engines are girly.

Well I don't know, ever hear a BAC-111 takeoff on a calm, cold morning? Now that will shake your fillings lose. :}

As for afterburner (re-heat) equipped aircraft, have not heard anything that could touch a B-58.

For overall noise, the B-36.

con-pilot 28th Jun 2015 16:21


Originally Posted by ehwatezedoing (Post 9027343)
Apparently Saturn V's lift off were quite something! :eek:


Oh hell, you have a winner there that wins hands down, nothing can compare to the noise of a Saturn V. The noise that thing makes tears at your soul, your whole body vibrates and that is when you're three miles or so from the launch site, maybe more as I have forgotten.

charliegolf 28th Jun 2015 16:57

Saturn V. Did I dream it, or is it the case that thousands of nearby birds just upped and dropped dead when they lit the candle? If yes, why? Air pressure changes?

CG

Loose rivets 28th Jun 2015 17:19

Sumburgh, standing (in polished shoes) on the edge of the grass waiting for a green light to cross. Why was I waiting? There, to the north, a black dot was steadily becoming four black dots. I looked south to Sumburgh Head cliffs and lighthouse, wondering when he was going to overshoot - I refused to believe the Vulcan was going to land. I was right, but it was around 20' and right beside me as the wheels were being tucked away.

Concorde used to hammer one's chest, but this was beyond imaginable - the sound seemed to be emulsifying me organs. I needn't have worried about the cliffs, as suddenly I was looking at the tops of the wings.

Just one of those magic moments.


Looking back, it's astonishing to think an airline could just set up in somewhere like Luton and make the noise those 1-11s did. I sometimes stayed with S-I-L not a mile from the end of the runway. Powder used to spill from widening cracks as they took off.

I was gone by then, but told that a bunch - more like a hoard - of Vauxhall workers turned up at the airport and explained why this noise was going to stop. I think the explanation involved the items they were carrying.

The night ban came soon after that and when I went back to LGW, the silence on the night airwaves was astonishing.

Shack37 28th Jun 2015 17:23

Experienced many a Vulcan departure from St. Athan early sixties after a major srvicing at the MU. BEs, 2 Wing mess being adjacent to Rway and of wooden structure, vibrated mightily as did plates and cutlery etc.


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