kaddyuk
Posts: 3697
Joined: Thu Nov 08, 2001 1:04 am

How Does Gyroscopic Rigidity Affect A Turbofan?

Fri Dec 03, 2004 8:24 am

Just a question that I asked myself that I couldnt answer...

Does gyroscopic rigidity affect an engine and its frame? If so, How? and When and what can it effect?
Whoever said "laughter is the best medicine" never had Gonorrhea
 
PhilSquares
Posts: 3371
Joined: Sun Mar 28, 2004 6:06 pm

RE: How Does Gyroscopic Rigidity Affect A Turbofan?

Fri Dec 03, 2004 8:58 am

The biggest area affected is the fan section. On the PW 2000/4000, the outer fan ring and fan blade tips have been the subject of several ADs. When the 4000 first entered service on the -400, there was substantially much more fan tip erosion than expected, some of this was attributable to FOD, but there was an issue with gyroscopic effects on the N1 section.
Fly fast, live slow
 
SATL382G
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Joined: Sat Aug 14, 2004 12:02 am

RE: How Does Gyroscopic Rigidity Affect A Turbofan?

Fri Dec 03, 2004 9:54 am

OK, what is gyroscopic rigidity?

Is this related to the ovalization problems the first 747s had?
"There’s nothing quite as exhilarating as being shot at and missed" --Winston Churchill
 
kaddyuk
Posts: 3697
Joined: Thu Nov 08, 2001 1:04 am

RE: How Does Gyroscopic Rigidity Affect A Turbofan

Fri Dec 03, 2004 10:12 am

http://www.howstuffworks.com/gyroscope.htm

I know what it is, but its god damned hard to explain it... I hope that by reading that article you might find an answer :S
Whoever said "laughter is the best medicine" never had Gonorrhea
 
411A
Posts: 1788
Joined: Mon Nov 12, 2001 10:34 am

RE: How Does Gyroscopic Rigidity Affect A Turbofan?

Fri Dec 03, 2004 3:15 pm

This slight problem has manifested itself on several aircraft, but only to a rather minor degree.

Nacelle 'pod-nod' on the Lockheed TriStar, for example.
Altho initially caused by VIGV oscillations, the entire nacelle gets to a movin' and sure can look rather odd to the unwary passenger.
 
avt007
Posts: 1989
Joined: Mon Jul 10, 2000 4:51 am

RE: How Does Gyroscopic Rigidity Affect A Turbofan?

Sat Dec 04, 2004 1:50 am

Gyroscopic forces are blamed for ripping the engines off the Airbus that lost its' vertical stabilizer.
 
MD11Engineer
Posts: 13916
Joined: Sun Oct 26, 2003 5:25 am

RE: How Does Gyroscopic Rigidity Affect A Turbofan

Sat Dec 04, 2004 2:41 am

On many modern jet engines, esp. the PW4000 series, the reverser cowl supports the engine housing and gives it additional rigidity especially on rotation to prevent it from bending under the gyroscopic forces of the shaft. This feature is called a load sharing cowl and incorporates additional latches. You can´t run the engine with the c-duct open.
If the load sharing latches are not properly adjusted or closed in the correct sequence, on rotation the fan or the rear turbine stages can touch the fan case, respectively the turbine housing. You can see it by irregular wear on the rub strip in the fan case.

Jan
Je Suis Charlie et je suis Ahmet aussi

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