A aviation & planes forum. AviationBanter

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » AviationBanter forum » rec.aviation newsgroups » Piloting
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

Engine-out procedures and eccentric forces on engine pylons



 
 
Thread Tools Display Modes
  #1  
Old May 23rd 07, 12:23 PM posted to rec.aviation.piloting
Mxsmanic
external usenet poster
 
Posts: 9,169
Default Engine-out procedures and eccentric forces on engine pylons

Long ago it occurred to me that a twin-engine jet running with one engine out
might be putting tremendous eccentric stress on the plyon and mounting of the
running engine (meaning stress not aligned with the normal thrust vector of
the engine). Today it occurred to me that this might not be true if the
pilots adjust the attitude of the aircraft so that it is flying straight
forward. The adjustments would create opposing forces that not only keep the
aircraft in level flight but also realign the stress on the running engine, as
if there were still two engines and symmetric forces on the pylons.

Does this make sense? If so, are there limits to how far an aircraft can fly
out of trim in such a way as to put unusual stress on engine pylons (even with
all engines running). For example, does yawing sharply in a large jet put
unacceptable stress on the pylons?

--
Transpose mxsmanic and gmail to reach me by e-mail.
  #2  
Old May 23rd 07, 01:50 PM posted to rec.aviation.piloting
Bob Moore
external usenet poster
 
Posts: 291
Default Engine-out procedures and eccentric forces on engine pylons

Mxsmanic wrote
For example, does yawing
sharply in a large jet put unacceptable stress on the pylons?


You should see what those pylons do in heavy turbulence!
The only stress is on the pilot who looks at them. :-)

Bob Moore
  #3  
Old May 23rd 07, 02:14 PM posted to rec.aviation.piloting
BDS[_2_]
external usenet poster
 
Posts: 149
Default Engine-out procedures and eccentric forces on engine pylons


"Bob Moore" wrote...

You should see what those pylons do in heavy turbulence!
The only stress is on the pilot who looks at them. :-)


My wife and I were on a flight a few years back in an A300 IIRC and we were
in seats that gave us a clear view of the engine on the left wing. I was
casually looking out at it when I noticed that it was oscillating back and
forth quite noticeably and considerably, and we were only in light chop at
the time. My first impression was HOLY #$%&! quickly followed by the
realization that since it hadn't come off yet it must be normal.

Judging by how much it was moving around you would have thought it was held
on with bungee cords.

BDS


  #4  
Old May 23rd 07, 03:50 PM posted to rec.aviation.piloting
Bob Moore
external usenet poster
 
Posts: 291
Default Engine-out procedures and eccentric forces on engine pylons

BDS wrote
Judging by how much it was moving around you would have thought it was
held on with bungee cords.


Nope! Back in my B-707 days, the engine was attached to the pylon
with just three bolts about the size of your forefinger, and each of
these bolts was designed to break-away and release the engine before
it could do damage to the wing.

Bob Moore
  #5  
Old May 23rd 07, 05:03 PM posted to rec.aviation.piloting
Mxsmanic
external usenet poster
 
Posts: 9,169
Default Engine-out procedures and eccentric forces on engine pylons

Bob Moore writes:

You should see what those pylons do in heavy turbulence!
The only stress is on the pilot who looks at them. :-)


I've seen engine nacelles swaying merrily to and fro (along the wing axis) in
turbulence but I didn't know if twisting forces applied to the pylons would be
so easily tolerated.

As it is, modern pylons, so seemingly frail and so apparently inviting of very
concentrated stresses as they hold the engines way out in front of the wing,
always look like an invitation for trouble to me. But I suppose if they are
engineered properly they can hold, rather like that glass walkway that the
Havasupai recently built out over the Grand Canyon.

--
Transpose mxsmanic and gmail to reach me by e-mail.
  #6  
Old May 23rd 07, 05:04 PM posted to rec.aviation.piloting
Mxsmanic
external usenet poster
 
Posts: 9,169
Default Engine-out procedures and eccentric forces on engine pylons

Bob Moore writes:

Nope! Back in my B-707 days, the engine was attached to the pylon
with just three bolts about the size of your forefinger, and each of
these bolts was designed to break-away and release the engine before
it could do damage to the wing.


Well, that's certainly reassuring.

--
Transpose mxsmanic and gmail to reach me by e-mail.
  #7  
Old May 23rd 07, 05:11 PM posted to rec.aviation.piloting
Erik
external usenet poster
 
Posts: 166
Default Engine-out procedures and eccentric forces on engine pylons

BDS wrote:
"Bob Moore" wrote...


You should see what those pylons do in heavy turbulence!
The only stress is on the pilot who looks at them. :-)



My wife and I were on a flight a few years back in an A300 IIRC and we were
in seats that gave us a clear view of the engine on the left wing. I was
casually looking out at it when I noticed that it was oscillating back and
forth quite noticeably and considerably, and we were only in light chop at
the time. My first impression was HOLY #$%&! quickly followed by the
realization that since it hadn't come off yet it must be normal.

Judging by how much it was moving around you would have thought it was held
on with bungee cords.

BDS



I love the window seat, but dammit, I cannot look at the wing
ever. "Ok, if it didn't flex like that, it would be brittle
and snap. It's supposed to bounce, it's not supposed to break"

But nothing reassures me.

  #8  
Old May 23rd 07, 05:29 PM posted to rec.aviation.piloting
TheSmokingGnu
external usenet poster
 
Posts: 166
Default Engine-out procedures and eccentric forces on engine pylons

Erik wrote:
I love the window seat, but dammit, I cannot look at the wing
ever. "Ok, if it didn't flex like that, it would be brittle
and snap. It's supposed to bounce, it's not supposed to break"

But nothing reassures me.


I find it helps in cases like these to watch a few videos of wing
loading tests, so you can see really just *how* far those wings can go
before breaking.

http://www.youtube.com/watch?v=6Uo0C01Fwb8

TheSmokingGnu
  #9  
Old May 23rd 07, 08:41 PM posted to rec.aviation.piloting
Richard
external usenet poster
 
Posts: 13
Default Engine-out procedures and eccentric forces on engine pylons


"Erik" wrote in message
...

I love the window seat, but dammit, I cannot look at the wing
ever. "Ok, if it didn't flex like that, it would be brittle
and snap. It's supposed to bounce, it's not supposed to break"

But nothing reassures me.


I find counting missing rivets and watching spinning rivets takes my mind
off the wing flex.


  #10  
Old May 24th 07, 12:10 AM posted to rec.aviation.piloting
muff528
external usenet poster
 
Posts: 304
Default Engine-out procedures and eccentric forces on engine pylons


I love the window seat, but dammit, I cannot look at the wing
ever......


1971 - My very first airline ride -- Delta DC-9 Tampa to Atlanta
The wing looked very solid and very much "one with the airplane" --o--

30 minutes later - My second airline ride -- PanAm 747 Atlanta to LA
I coulda swore that the wings were flapping ~~o~~

I missed a lot of scenery :-)

TP


 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Westland Wyvern Prototype - RR Eagle Engine - Rolls Royce Eagle 24cyl Liq Cooled Engine.jpg Ramapo Aviation Photos 0 April 17th 07 09:14 PM
Saturn V F-1 Engine Testing at F-1 Engine Test Stand 6866986.jpg [email protected] Aviation Photos 1 April 11th 07 04:48 PM
F-1 Engine for the Saturn V S-IC (first) stage depicts the complexity of the engine 6413912.jpg [email protected] Aviation Photos 0 April 9th 07 01:38 PM
1710 allison v-12 engine WWII p 38 engine Holger Stephan Home Built 9 August 21st 03 08:53 AM
Jettisonable Pylons? Jeroen Wenting Military Aviation 3 July 6th 03 05:07 AM


All times are GMT +1. The time now is 02:07 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2023, Jelsoft Enterprises Ltd.
Copyright 2004-2023 AviationBanter.
The comments are property of their posters.