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tthew-man

A Question About Reverse Thrust

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Does anyone know how fast reverse thrust is meant to respond (not the reverser deployment time but the spool time), as well as what the max N1 is supposed to be, on the -200LR?  I'm under the (perhaps mistaken) impression that the response time is a bit too slow on the LRX, and that the max N1 is too low.  For clarification, I'm getting a max N1 of about 55, whereas I thought it was supposed to be in the high 70's or low 80's.  Can anyone enlighten me?

 

Thanks,

 

Matthew Gauff

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@Peter James Normally reversers spool up to about 70 or 80% N1 of max normal power..... if it's too low, and there was some actual mistake made, you can up it in your aircraft.cfg maximum reverse throttle number to like .29 or something will bring it way up to about 70 or 80% (I have had to do this to many flightsim airliners). I don't own the 777 by PMDG yet, so can't say for sure.....

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@Peter James Normally reversers spool up to about 70 or 80% N1 of max normal power..... if it's too low, and there was some actual mistake made, you can up it in your aircraft.cfg maximum reverse throttle number to like .29 or something will bring it way up to about 70 or 80% (I have had to do this to many flightsim airliners). I don't own the 777 by PMDG yet, so can't say for sure.....

 

With due respect to Peter, do NOT do this to your PMDG 777. Bad idea.

 

a ) The reverse thrust is modelled faithuflly.

b ) Messing with aircraft cfg files can have undesired consequences for advanced add-ons.

 

As for the OP's question: I don't recall having any issues with reverse thrust. Look into the manuals and see what they say about the reverse thrust N1, if you find a disparity between the book figure and what you;re seeing, sing out and we'll take a closer look..

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Yeah as far as messing with the .cfg file....  that's the first thing I would have done had this been a freeware aircraft or something else, but with advanced airliners like this..... not a good idea.  Unfortunately, I exhaustively poured over all the documentation that came with this wonderful plane and did not see anything relating to reverse thrust N1, although I did find another issue: reversers are supposed to be available as soon as the mains touch down, and the autothrottles are supposed to disconnect.  Instead, they remain at "idle" and I'm unable to select reverse thrust promptly.  I tried changing the "A/T manual override" to "always" and that seems to have helped, but I'm still concerned about reverse N1.  Here's a video that shows an N1 in the high 70's on an RTO.  Although it's a simulator I'm pretty sure it's a level D and has all the capabilities that a 777 would have:

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I also found an FAA document (although it's for the -200ER I assume the two are pretty similar) with graphs about N1 speed at various stages (takeoff, TR deployment and while TR's are deployed) of flight, and according to it (the graph is on the last page of the document) some TR's are deployed at around 55% N1, and some reach as high as about 75% while TR's are deployed.

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My comment is reverse thrust seems too strong.  I only need reverse idle and auto 1 to stop/slow to taxi after landing and it seems like too short of a distance.  Is this normal?  I've seriously never had to use more than idle reverse.  

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My comment is reverse thrust seems too strong. I only need reverse idle and auto 1 to stop/slow to taxi after landing and it seems like too short of a distance. Is this normal? I've seriously never had to use more than idle reverse.

Landing light on a long runway, auto brakes 1 should be fine.

 

Auto brakes command a constant deceleration. The use of thrust reverse will therefore not reduce landing distance, only reduce the load on the brakes.

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