RB 211 r.p.m.
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RB 211 r.p.m.
I'm not connected with the industry at all (only by enthusiasm, if that counts).
I've just been to New York from Manchester and return, courtesy B.A. (excellent service, I might add, even for us in Steerage), and whilst we were gently wafting our way back across the Atlantic, listening to the 211's thrumming away outside, the thought occurred - Whilst at cruise, given "Average" everything, weather, weight, altittude, W.H.Y?, what r.p.m. are the engines turning at?
I've just been to New York from Manchester and return, courtesy B.A. (excellent service, I might add, even for us in Steerage), and whilst we were gently wafting our way back across the Atlantic, listening to the 211's thrumming away outside, the thought occurred - Whilst at cruise, given "Average" everything, weather, weight, altittude, W.H.Y?, what r.p.m. are the engines turning at?
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jtr,
Thanks for the reply, but not being in the profession, I don't know what the "N" numbers represent.
I'd be obliged if you could explain.
Thanks. N.Z.
Thanks for the reply, but not being in the profession, I don't know what the "N" numbers represent.
I'd be obliged if you could explain.
Thanks. N.Z.
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Rolls, uniquely in the modern era, use three spool engines.
N1 refers to the Low Pressure shaft (that’s the one you can see at the front and back of the engine)
N2 is the intermediate pressure shaft, and strangely N3 is the High pressure shaft.
They are commonly abbreviated to LP, IP, & HP.
Pratt & GE use two shaft engines i.e. N1 & N2.
I know this is over simplistic but it is outside my area of expertise what with me being a simple Avionic sort of chap, I have no idea why Rolls plough their own, particular, furrow.
N1 refers to the Low Pressure shaft (that’s the one you can see at the front and back of the engine)
N2 is the intermediate pressure shaft, and strangely N3 is the High pressure shaft.
They are commonly abbreviated to LP, IP, & HP.
Pratt & GE use two shaft engines i.e. N1 & N2.
I know this is over simplistic but it is outside my area of expertise what with me being a simple Avionic sort of chap, I have no idea why Rolls plough their own, particular, furrow.
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Well, thanks for the info, guys. I am perhaps fortunate in that I never cease to be amazed at the engineering miracle that is Aviation.
Just based very broadly on the figures given, the N3 shaft in each of the 211's that carried me turned over 4 million in one crossing of the Atlantic.
They performed the same coming back over here, then to my knowledge, performed the same again a few days later bringing me home again!
And as far as I know, they did it a few more times whilst I was there, and are probably still doing it now!
What a lump of kit.!
Just based very broadly on the figures given, the N3 shaft in each of the 211's that carried me turned over 4 million in one crossing of the Atlantic.
They performed the same coming back over here, then to my knowledge, performed the same again a few days later bringing me home again!
And as far as I know, they did it a few more times whilst I was there, and are probably still doing it now!
What a lump of kit.!
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Someone has too much time on their hands!
Not really all that impressive, only takes about 4 revolutions to move 1 metre, consider how much suck, squeeze, bang, blow is going on in your car to do the same at cruise speed.
Takes about 2 revolutions/mt on my car.
Sitting by for technical corrections
Not really all that impressive, only takes about 4 revolutions to move 1 metre, consider how much suck, squeeze, bang, blow is going on in your car to do the same at cruise speed.
Takes about 2 revolutions/mt on my car.
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Hi jtr,
that suck, squeeze, bang and blow is going on in ALL combustion engines, automotive as well as aviation (and all others!).
Just thought I'd mention it!!!
No probs,
Cheers
that suck, squeeze, bang and blow is going on in ALL combustion engines, automotive as well as aviation (and all others!).
Just thought I'd mention it!!!
No probs,
Cheers
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Yeh, ahhh thanks for the heads up FD
The trauma of the SSBB in a recip engine all occuring in the same place was my (unstated) point.
But while you are here, can you tell me why a Roller will give an EPR <1.0 when in idle descent?
The trauma of the SSBB in a recip engine all occuring in the same place was my (unstated) point.
But while you are here, can you tell me why a Roller will give an EPR <1.0 when in idle descent?
Usual disclaimers apply!
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In descent at idle ram pressure will be greater than exhaust pressure so the indicated EPR will be less than 1 (typically 0.9).
At idle on the deck, EPR will read about 1.02.
At idle on the deck, EPR will read about 1.02.
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woderick Working with those in the know apparently:- the design makes them lighter as there are less compressor stages and also because of this they are inherently shorter.
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A couple of points.....
Firstly, EPR in a high speed descent (in my experience) will only get down to 0.97.... Not 0.9, that's REALLY low!!!
And secondly, I believe that the economics of the three spool engine (in addition to the above) come from the fact that more compressor stages are working at optimum RPM with the addition of the intermediate pressure turbine...
BN2A
Firstly, EPR in a high speed descent (in my experience) will only get down to 0.97.... Not 0.9, that's REALLY low!!!
And secondly, I believe that the economics of the three spool engine (in addition to the above) come from the fact that more compressor stages are working at optimum RPM with the addition of the intermediate pressure turbine...
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Yeh, I'm with coldstream on this one. Had checker tell me it was because the outlet pressure sensors are only hotstream (have a look up the back of a trent 772 sometime) I didn't buy it.
