SuseJ772
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Turbulence & Its Effects On The Tail And Elevators

Mon Aug 22, 2005 11:59 pm

Alright, I have read post after post regarding turbulence, and I am finally willing to believe that wings aren't going to snap off  Smile However, at this point what I am more interested in our the stress factors placed on the tail and elevators? It would seem to me that just like the wing, there would be great force placed on these particular components, but I thought I read in another post someone saying in a passing comment that there is not much force placed on these elements? Is that true? Thanks!
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FredT
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RE: Turbulence & Its Effects On The Tail And Elevators

Tue Aug 23, 2005 1:04 am

Define "a great force"? There are forces on the tailplanes. That is what they are there for, to create the forces which enable stable and controlled flight. For large aircraft, these forces are large. Turbulence can increase those forces further, but the aircraft is designed to withstand them.

(And yes, you can create larger forces than those intended during the design phase on most components of an aircraft - just before anyone mentions AA587).

[Edited 2005-08-22 18:04:40]
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SuseJ772
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RE: Turbulence & Its Effects On The Tail And Elevators

Tue Aug 23, 2005 8:33 am

I guess what I meant by a great force is something that can cause catastrophic separation of the tail components. I've seen the "g-ratings" the wing can withstand, what about the tail components? I've also seen the numbers on how much flex/bend the wings can withstand, what about the tail components? To put it in less scientific terms, is the wing or the tail components more likely to snap off? I know that might seem really simplistic, but that is the type of discussion I am looking for.
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FredT
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RE: Turbulence & Its Effects On The Tail And Elevators

Tue Aug 23, 2005 5:38 pm

They are certified to the same load factors, i e designed to withstand the same multiple of the calculated maximum loads. The answer is that neither is likely to break and that wings and tailplanes are just as safe.

No offense, but would you by any chance be part of the crowd who are scared of flying or is the reason for you asking something else? Just so we can answer your questions better...

Cheers,
Fred
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SuseJ772
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RE: Turbulence & Its Effects On The Tail And Elevators

Wed Aug 24, 2005 3:23 am

Quoting FredT (Reply 3):
No offense, but would you by any chance be part of the crowd who are scared of flying or is the reason for you asking something else? Just so we can answer your questions better...

FredT that is a very interesting question. I'm 23-years old, and in the past four years, I have flown 137,099 miles (yeah, I'm anal retentive). Ever since I was young I have always been fascinated with flying, yet at the same time afraid of it. My three biggest fears in life are 1.) claustrophobia, 2.) heights and 3.) lack of control - you pretty much combine those into one thing and you have flying. Yet, I have always had a desire to become a pilot (professionally at one point, and now just as a hobby). I know, its strange isn't it. Over the years I have become a lot more settled with my flying due to in large part Tech/Ops (I've been reading for about three years now) and the brilliant answers by SlamClick, StarlionBlue, and the rest. I have come to realize the wings aren't going to snap off, certain noises during take-off/landing are normal, and the list goes on and on. But very rarely do people talk about the tail, and stress applied to it and so that is the source of my question.

When it really gets down to it, I understand the tail is certified to certain load factors just like the wings, but what I was trying to figure out is does the tail and elevators "bend" like the wings do, or is most of the stress factors placed on a plane applied to the wings?
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FredT
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RE: Turbulence & Its Effects On The Tail And Elevators

Wed Aug 24, 2005 5:00 pm

Great, now we are on the same page.  Smile

Any stress applied to any structure will cause flex in the structure. In a stressed skin structure, much of the stress is absorbed by the skin buckling. This can even be visible in an aircraft! Most of the stress on wings, elevators etc is absorbed by the spars bending.

So yes, the fuselage, landing gear, elevators, vertical tail etc all flex just like the wings as loads are applied. This is a Good Thing(tm). As long as a structure can flex, it won’t break!

The largest force by far on an aircraft is the lift and it is applied to the wings. In the air, the entire aircraft is resting on the wings.

If you get the chance and haven’t already, do go flying! Most people scared of heights aren’t bothered when flying, claustrophobia isn’t an issue when you have windows with the best view in the world all around you and controlling the aircraft should abolish any feeling of letting go of the control of your life.  Smile

Cheers,
Fred
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Starlionblue
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RE: Turbulence & Its Effects On The Tail And Elevators

Wed Aug 24, 2005 11:39 pm

Quoting SuseJ772 (Reply 4):
When it really gets down to it, I understand the tail is certified to certain load factors just like the wings, but what I was trying to figure out is does the tail and elevators "bend" like the wings do, or is most of the stress factors placed on a plane applied to the wings

As FredT says, it all bends and twists. If you fly a long, thin airliner where you can see down the aisle (752 for example), you might see the fuse twist during turbulence.

Quoting SuseJ772 (Reply 4):
Over the years I have become a lot more settled with my flying due to in large part Tech/Ops (I've been reading for about three years now) and the brilliant answers by SlamClick, StarlionBlue, and the rest

While I am flattered to be mentioned in the same breath as SlamClick, and I am gratified that my contributions are useful, it should be remembered that SlamClick is a professional pilot instructor with 40+ years experience, and I am but a freakishly aviation interested groupie who sits in the back a lot. Big grin
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
gmidy
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RE: Turbulence & Its Effects On The Tail And Elevators

Thu Aug 25, 2005 3:13 pm

Don't forget turbulence is a constant gust so to speak of air ie unstable air, moving maybe in the opposite direction to the aircraft this interupts the airflow causing the "bump" you feel, the Airbus aircraft wings are bent to angles as far as 30 degrees and do not snap if you want to test this theory get a bendy type of metal such as steel ruler, attach it to a lever device or vice or something similar to hold it in place now try and snap it. Off topic Airbus also fire frozen chickens at the cockpit windscreen at 300mph to test the hit resistance..

[Edited 2005-08-25 08:16:52]
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FredT
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RE: Turbulence & Its Effects On The Tail And Elevators

Thu Aug 25, 2005 4:46 pm

For those who are not familiar with it, the frozen chicken story is an industry joke turned urban legend...
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Starlionblue
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RE: Turbulence & Its Effects On The Tail And Elevators

Thu Aug 25, 2005 10:15 pm

Quoting FredT (Reply 8):
For those who are not familiar with it, the frozen chicken story is an industry joke turned urban legend...

Indeed. The chickens are, in fact, thawed first.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
SuseJ772
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RE: Turbulence & Its Effects On The Tail And Elevators

Fri Aug 26, 2005 3:59 am

Quoting Starlionblue (Reply 6):
While I am flattered to be mentioned in the same breath as SlamClick, and I am gratified that my contributions are useful, it should be remembered that SlamClick is a professional pilot instructor with 40+ years experience, and I am but a freakishly aviation interested groupie who sits in the back a lot. Big grin

I guess that must have been why I mentioned him first.  Smile Nevertheless, you've been very helpful.
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