PDA

View Full Version : Trent 900 Centrifugal forces (A380)


F/O UFO
1st Mar 2009, 20:20
Hi, I was just wondering if anyone has any facts and figures about the centrifugal forces generated when the Trent 900 runs at full thrust?

Also, can anyone enlighten me as to the construction of the engine casing- and how it can manage to withstand a fanblade break?

The RR website is lacking very much in stats, the only information I have is from the EASA.

Any help would be muchg appreciated

F/O UFO
2nd Mar 2009, 20:16
Okay, does anyone have any good tech specs on trent 900? I am looking for weights of fan blades, centrifugal/ centripetal forces, fan blade construction, outer casing construction...

any help would be great

lomapaseo
2nd Mar 2009, 20:42
centrifugal forces are reacted against the rotor disk and produce stresses. The idea is to make the disk thick enough to keep the average stresses way below the yield strength of the material and allow for margins with the UTS of 50% or more.

Assuming everything remains in balance the aircraft and passenger never feel centrifugal force no matter how big the engine.

In a blade out situation the unbalance forces created by the remaining blades still spinning react against the bearing supports and ultimately the engine mounting and the wing. These forces as direct loading are quite large but are easily accomodated with a couple of square inches of solid metal between the engine and the wing. Unfortunately the cyclic effect is enough to make your teeth rattle

The forces generated against the case when a blade comes loose are not realistically calculable since they are determined by the rate of decelleration (several micro-seconds) and even then are only felt extremely locally by the case material. The containment itself is closely related to a ballistic impact event (like a bullet against armour) and is pretty much an energy balance between the case material potential energy and the blade moving at about half the speed of sound. The idea here is to make the impact last long enough to use the potential energy in the case material and not have it shatter.

F/O UFO
2nd Mar 2009, 21:12
Thanks alot lomapaseo.

I was gunna try and calculate the centripetal/ centrifugal force generated, however that looks hard accuratly- because of the changeing length and weight of fan blade. Approximatly how much does a fan blade on a Trent 900 sized engine weigh? I watched a programme on how they are hollow in parts.

Back Seat Driver
2nd Mar 2009, 22:51
F/O UFO
It might look a little like this.
<object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/mY6KnPfR5xc&hl=en&fs=1"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/mY6KnPfR5xc&hl=en&fs=1" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed></object>

beachbumflyer
3rd Mar 2009, 01:22
Guys,
The centrifugal force does not exit. Ask a phisics professor and he will
prove it to you.

Loose rivets
3rd Mar 2009, 04:29
Mmm...can't seem to find one, you'll have to do.


We're all ears.

Mark1234
3rd Mar 2009, 06:03
It's a centrepital(sp?) acceleration (or so my phisics teacher kept telling me - never really quite got it..) but when you stop accelerating it into a circular path, the sh*t hits the fan - or did the fan hit the ?? :E

Perhaps we can just say it all goes a bit pear shaped..

F/O UFO
3rd Mar 2009, 07:59
yes, centrifugal force is ficticious, however it is usefull when looking at the foces perpendicular to the centre of motion.

Haha, I think the fan hits the Sh**