Hello all:

 

I am having trouble understanding the tables provided by PMDG Simulations respecting reduced thrust. Sometimes I create t/o issues and while I understand the concept, but I don't understand the variables or when I should choose reduced thrusts. 

I certainly don't understand the FMC N1 LIMIT page where I have T/O derate choices and climb choices.

Does someone have a reading link I may go to for help? --- or if there is an "expert" who can teach me here I would give you an email address where we can hook up outside of this forum.

 

Thank you

 

Mike Chute

 

 

 

I certainly don't understand the FMC N1 LIMIT page where I have T/O derate choices and climb choices.

 

Running an engine at redline all day is going to reduce its life.

 

Think of it like this:

Go outside and run as fast as you can.  You're not going to last very long.

Now, go outside and run at a slower pace.  You'll run a lot farther.

 

Same thing with engine wear:

Running the engine without reducing the thrust stresses it more than is necessary.

Reducing the thrust limit to a level that is still safe for takeoff allows the engine to operate with less stress.

 

So, using reduced thrust, where able, helps to cut engine maintenance costs.  Obviously, maintenance costs in the sim are not an issue, but the option is there for those who want to simulate this.

 

If you want realistic calculations for reduced thrust (it's done on a per-runway basis) you'll need a tool like TOPCAT.

As I said in my post, I understand the concept but unfortunately I can not afford another payware solution. I was looking for someone who has referred to the PMDG manual and can work me through the tables therein so I can choose the correct t/o rates on the FMC myself. Thank though for you analogy

 

Mike Chute

You can determine max reduce thrust through FCOM tables easily.

Have you looked at this spreadsheet? It has performance calculations for 737-600,700,800 and 900.

 

http://forum.avsim.net/topic/405110-free-alternative-to-topcat/?hl=%2Bautoland#entry2656819

The link above unfortunately doesn't seem to work however it leads to a revised excel sheet created by Frederic FURST with permission from Lasse Kronborg and it looks promising. Thank you for this

 

Mike Chute