Thanks
Andy
Max continuous thrust
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AJW
- Posts: 197
- Joined: Wed Sep 23, 2009 5:41 pm
Max continuous thrust
I was sat on one side of a rather thick wall with a Conway running at max continuous thrust on the other side a short while ago which got me wondering when that thrust setting would be used.....Would any of you pilot types be able to help? Would it ever be used for instance; transatlantic if you needed to get somewhere fast? Or as a ToGa setting? Or an engine failure? When would you use absolute max thrust?
Thanks
Andy
Thanks
Andy
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Tonkenna
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Re: Max continuous thrust
Max Continuous was used for several reasons:
It could be used in the climb to either get to height quicker or (counter-intuitivley) to save fuel though what you would actually set is Operational Essential Power... there is a difference and if I get time I will explain later.
It could be used in the cruise if an engine failed in order to maintain height as long as possible. If you lost an engine above the 3-engine height you would set Max Cont, and then gently drift down to the 3-eng stabilisation ht and continue at that.
You would not use it in the cruise on 4 engines as you would easily exceed VNO/MNO.
Max Continuous Power is not the equivalent to TOGA... on a Go Around on 3 or 4 engines you would set 96% were as on T/O with the loss of an engine you may set full power (ie 100% or whatever you get - possibly a bit more or a bit less). Most Take-offs were not at full power btw.
So it is more complicated than just a simple choice of a power setting... Max Continuous is still fairly hard on the engine and whilst there isn't a time limit you would avoid sitting at it for a long time if possible... but it was there to be used if required. Normally in the cruise you would be at 92% HP RPM or less and at altitude you would be power limited anyway on HP RPMs so that you did not surge the engine...
Max thrust is generally used when you need to get away from the ground in a hurry eg go around from below a decision height, engine failure or even worse a double-engine failure... we have to do a full power take-off every now and then (every 10 or so T/Os) to check the engines... but there is a time limit on full power.
Blimey.. I could go on, but I have to shoot...
I may revisit this when I have more time as this is all a bit disjointed...
Tonks
It could be used in the climb to either get to height quicker or (counter-intuitivley) to save fuel though what you would actually set is Operational Essential Power... there is a difference and if I get time I will explain later.
It could be used in the cruise if an engine failed in order to maintain height as long as possible. If you lost an engine above the 3-engine height you would set Max Cont, and then gently drift down to the 3-eng stabilisation ht and continue at that.
You would not use it in the cruise on 4 engines as you would easily exceed VNO/MNO.
Max Continuous Power is not the equivalent to TOGA... on a Go Around on 3 or 4 engines you would set 96% were as on T/O with the loss of an engine you may set full power (ie 100% or whatever you get - possibly a bit more or a bit less). Most Take-offs were not at full power btw.
So it is more complicated than just a simple choice of a power setting... Max Continuous is still fairly hard on the engine and whilst there isn't a time limit you would avoid sitting at it for a long time if possible... but it was there to be used if required. Normally in the cruise you would be at 92% HP RPM or less and at altitude you would be power limited anyway on HP RPMs so that you did not surge the engine...
Max thrust is generally used when you need to get away from the ground in a hurry eg go around from below a decision height, engine failure or even worse a double-engine failure... we have to do a full power take-off every now and then (every 10 or so T/Os) to check the engines... but there is a time limit on full power.
Blimey.. I could go on, but I have to shoot...
I may revisit this when I have more time as this is all a bit disjointed...
Tonks
Please check out my Flickr account: http://www.flickr.com/photos/zz330/
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AJW
- Posts: 197
- Joined: Wed Sep 23, 2009 5:41 pm
Re: Max continuous thrust
Thanks for the info Tonks, very helpful and interesting