I have a few components in the fmc which i am unsure which information to enter:The cg, cost index, n1 temperature to calculate thrust (ifly 737ng). How do I calculate this data.

The best place to find answers for your questions would be on the iFly support forum: http://ifly.flight1.net/forums/default.aspCoG is given by the configuration tool.

CG (Center of Gravity) can be calculated a number of ways in FS (most easily with the iFly config tool). You can also do it manually by counting how many ticks (forward or backward) off dead centre the CG marker is on the fuel/payload window in the FS menu, but this is kind of tricky since the scale is about 1/4th of what you'd expect so you have to blag it a bit, thus it isn't the easiest way, or very accurate unless you have an Ariane FSX 737, which do have some cool tricks up their sleeve where this is concerned. On a real aircraft, the CG info will be on the loadsheet, which is handed to the crew by the ramp agent or loadmaster, although this is increasingly being replaced by an electronic system sent directly to the pilot's laptops when they are planning the flight, which is where you can simulate things more realistically in FS by using something such as TOPCAT, which is a payware product that allows you to simulate the loading and take of planning more like it is done in the real world. TOPCAT (take off and landing performance calculation Tool), can be found at the link below, although you can buy it from several online stores (think it cost me 15 quid):http://www.topcatsim.com/Cost Index is easy, but it will help you if you know what it actually is, so here goes.... CI is an index between the cost of operating an aircraft (in terms of hours and stress on the engines) versus the cost of fuel (as in literally how much fuel you will use for certain ways of flying the aeroplane, i.e. fast or economically, etc). The value range for the Cost Index on an NG is from 0-500 (on Classic 737s such as the 300/400/500 it was from 0-200). If you put 0 in the CI box, your NG will will try to fly as economically as possible using things such as LRC (long range cruise) mode etc to operate the engines in the most economical way, if you put 500 in the CI box, your NG will not give a crap about saving fuel and will instead go as fast as it can in order to save time (although it will limit itself to airspeed safety margins, such as a maximum speed of 330 knots in the descent, and any speed limits that you put in will still be adhered to). There is a caveat to all this though. It can actually be more economical to use a high CI, since your aeroplane will get up to cruise altitude quicker, where it can throttle back to cruise settings much sooner, and with the engines at higher climb settings, but as a result actually climbing much faster, they will spend less time at those higher thrust settings, thus putting less wear on the engines. Because of this, you will find that most airlines tend to go for somewhere around the 100 value for CI, although you can change the CI value en-route, for example, 500 on the climb, then 50 on the cruise etc, etc. Personally I just leave it on 100.N1/temp settings are usually automatic when you enter the correct value for Outside Air Temperature (OAT), and they are automatic for other things that alter the N1 too, for example, CLB-1 drops N1 by three percent for a ten percent thrust reduction, CLB-2 drops it by another ten percent, but both of these gradually increase to full power setting automatically with a target of 15,000 feet, where they will be completely back to normal.Nevertheless, you can override them with your own settings, by 'fooling' the FMC with different temperature inputs. By default, the CFM engines on a 737 are rated to give their full 'as advertised' thrust settings when the temperature is at or below ISA+15C. At a higher temperature than that, they will put out less thrust because the air is 'thinner', i.e. less dense. What that means is that when you have a long runway or a light load on your 737, and the temperature is below the value mentioned above, you can 'lie' to the FMC by putting in an outside air temperature (OAT) value that is much higher than it actually is in reality, so that the FMC will alter the way it works the engines. This is called entering an 'assumed temperature' (called a 'Flex temperature' on Airbus FMCs). Incidentally, this kind of thing is usually to blame when people say 'my 737 doesn't work climb the real one does', since you have to put the right temps into the FMC to get it to perform like the real thing.What actually happens on entering an assumed temp, is that the FMC will lower the N1 setting when you engage the TOGA (Take off/Go around) lever (arm the autothrottle and press Control+G in FSX). This might not seem to make sense, since you would think in high temperatures the plane would need to really ram the throttles open to get going fast in the thin air, but although it does need to get going fast, swamping the engines with warm thin air would not do that, so the engines suck it in a bit slower to prevent that happening. You do all this fancy trickery on the 'N1 Limit' page of the FMC, and the FMC itself does all the calculations for you.The easiest way to find that data in FS, is to look on the weather page, but you will find that using the 'weather brief' page in something like the payware Active Sky Evolution will make things a bit easier, as it will give you temps at various altitudes. But in simple terms, so long as you stick the right temperature in from what FS is telling you it is on the ground, it should work okay. Raise the value a bit for a reduced thrust take off (make sure you have plenty of runway or a light load though!).The range of assumed temperatures you can enter on an NG is from 16 up to 75, but in practice, 30-55 is a more normal range that is used on a practical basis. At the lowest settings, the engine will be flat rated at its advertised thrust setting, and then correspondingly less power will be used with anything above that. The main reason to do it is to reduce engine wear and tear when you have a light load or plenty of runway to spare, but it can also reduce the chances of picking up FOD (foreign object damage), from dirty runways, since there is less likelihood of something being sucked into the engine when it is operating on a bit lower power (not something you have to worry about in FS). Note too though, that a reduced thrust take off does actually use more fuel; even though you are theoretically using less fuel by reducing the thrust, the engines are not being used at full efficiency when you enter bogus values into the FMC, so you use more fuel.What you can see from all this, is that apart from the CG setting (which does need to be correct to have the LNAV and VNAV work properly), most of the other stuff is merely interesting to simulate, and it doesn't actually matter a lot on a simulated FS aeroplane where you have no maintenance costs and fuel is free, although it could potentially make your cruise slower.Also of interest, but not really something you can do in FS easily:You can actually do something called a 'double derate' take off on the real NG. This is when you enter an assumed temp and also alter the flat rate thrust value on an engine via the FMC on the 'N1 Limit' page (not always simulated in all FS FMCs and often locked out from being changed on the real aeroplane too, unless you are an engineer and know a few tricks such as simultaneously pressing the same keys on both FMCs to enter various hidden modes on the FMC). The real purpose of derating the engines is so that different models of CFM can be fitted on one (or both) sides of the aeroplane and then matched to the thrust values of the other engine (if they are oddly rated). The 600 series NG is one where this happens, since it has derated CFM engines.Thus you can alter the thrust ratings for both engines, and enter an assumed temperature value too, to get a 'double derated' take off). Note that unless you know what you are doing, this could be extremely dangerous, since you will effectively seriously underpower the aeroplane. Of course in Fs it is not 'dangerous', but you could still bugger up your install, so I would regard this as simply of interest rather than something to try and instead leave those thrust values alone.Some NGs also have an option called 'Bump Thrust', which is where the engines can be pushed beyond the normal values for take off in order to boost the aircraft off the runway using part of the thrust reversing mechanism (since the NG and Classics effectively have slightly vectored thrust from the way the engines are fitted onto it pointing down a bit). This is a customer option only and it cannot be used in conjunction with assumed temperatures. You probably won't see this simulated on an FS 737, although you never know, PMDG might go for it!Have fun!Al

CG (Center of Gravity) can be calculated a number of ways in FS (most easily with the iFly config tool). You can also do it manually by counting how many ticks (forward or backward) off dead centre the CG marker is on the fuel/payload window in the FS menu, but this is kind of tricky since the scale is about 1/4th of what you'd expect so you have to blag it a bit, thus it isn't the easiest way, or very accurate unless you have an Ariane FSX 737, which do have some cool tricks up their sleeve where this is concerned. On a real aircraft, the CG info will be on the loadsheet, which is handed to the crew by the ramp agent or loadmaster, although this is increasingly being replaced by an electronic system sent directly to the pilot's laptops when they are planning the flight, which is where you can simulate things more realistically in FS by using something such as TOPCAT, which is a payware product that allows you to simulate the loading and take of planning more like it is done in the real world. TOPCAT (take off and landing performance calculation Tool), can be found at the link below, although you can buy it from several online stores (think it cost me 15 quid):http://www.topcatsim.com/Cost Index is easy, but it will help you if you know what it actually is, so here goes.... CI is an index between the cost of operating an aircraft (in terms of hours and stress on the engines) versus the cost of fuel (as in literally how much fuel you will use for certain ways of flying the aeroplane, i.e. fast or economically, etc). The value range for the Cost Index on an NG is from 0-500 (on Classic 737s such as the 300/400/500 it was from 0-200). If you put 0 in the CI box, your NG will will try to fly as economically as possible using things such as LRC (long range cruise) mode etc to operate the engines in the most economical way, if you put 500 in the CI box, your NG will not give a crap about saving fuel and will instead go as fast as it can in order to save time (although it will limit itself to airspeed safety margins, such as a maximum speed of 330 knots in the descent, and any speed limits that you put in will still be adhered to). There is a caveat to all this though. It can actually be more economical to use a high CI, since your aeroplane will get up to cruise altitude quicker, where it can throttle back to cruise settings much sooner, and with the engines at higher climb settings, but as a result actually climbing much faster, they will spend less time at those higher thrust settings, thus putting less wear on the engines. Because of this, you will find that most airlines tend to go for somewhere around the 100 value for CI, although you can change the CI value en-route, for example, 500 on the climb, then 50 on the cruise etc, etc. Personally I just leave it on 100.N1/temp settings are usually automatic when you enter the correct value for Outside Air Temperature (OAT), and they are automatic for other things that alter the N1 too, for example, CLB-1 drops N1 by three percent for a ten percent thrust reduction, CLB-2 drops it by another ten percent, but both of these gradually increase to full power setting automatically with a target of 15,000 feet, where they will be completely back to normal.Nevertheless, you can override them with your own settings, by 'fooling' the FMC with different temperature inputs. By default, the CFM engines on a 737 are rated to give their full 'as advertised' thrust settings when the temperature is at or below ISA+15C. At a higher temperature than that, they will put out less thrust because the air is 'thinner', i.e. less dense. What that means is that when you have a long runway or a light load on your 737, and the temperature is below the value mentioned above, you can 'lie' to the FMC by putting in an outside air temperature (OAT) value that is much higher than it actually is in reality, so that the FMC will alter the way it works the engines. This is called entering an 'assumed temperature' (called a 'Flex temperature' on Airbus FMCs). Incidentally, this kind of thing is usually to blame when people say 'my 737 doesn't work climb the real one does', since you have to put the right temps into the FMC to get it to perform like the real thing.What actually happens on entering an assumed temp, is that the FMC will lower the N1 setting when you engage the TOGA (Take off/Go around) lever (arm the autothrottle and press Control+G in FSX). This might not seem to make sense, since you would think in high temperatures the plane would need to really ram the throttles open to get going fast in the thin air, but although it does need to get going fast, swamping the engines with warm thin air would not do that, so the engines suck it in a bit slower to prevent that happening. You do all this fancy trickery on the 'N1 Limit' page of the FMC, and the FMC itself does all the calculations for you.The easiest way to find that data in FS, is to look on the weather page, but you will find that using the 'weather brief' page in something like the payware Active Sky Evolution will make things a bit easier, as it will give you temps at various altitudes. But in simple terms, so long as you stick the right temperature in from what FS is telling you it is on the ground, it should work okay. Raise the value a bit for a reduced thrust take off (make sure you have plenty of runway or a light load though!).The range of assumed temperatures you can enter on an NG is from 16 up to 75, but in practice, 30-55 is a more normal range that is used on a practical basis. At the lowest settings, the engine will be flat rated at its advertised thrust setting, and then correspondingly less power will be used with anything above that. The main reason to do it is to reduce engine wear and tear when you have a light load or plenty of runway to spare, but it can also reduce the chances of picking up FOD (foreign object damage), from dirty runways, since there is less likelihood of something being sucked into the engine when it is operating a on a bit lower power (not something you have to worry about in FS). Note too though, that a reduced thrust take off does actually use more fuel; even though you are theoretically using less fuel by reducing the thrust, the engines are not being used at full efficiency when you enter bogus values into the FMC, so you use more fuel.What you can see from all this, is that apart from the CG setting (which does need to be correct to have the LNAV and VNAV work properly), most of the other stuff is merely interesting to simulate, and it doesn't actually matter a lot on a simulated FS aeroplane where you have no maintenance costs and fuel is free, although it could potentially make your cruise slower.Also of interest, but not really something you can do in FS easily:You can actually do something called a 'double derate' take off on the real NG. This is when you enter an assumed temp and also alter the flat rate thrust value on an engine via the FMC on the 'N1 Limit' page (not always simulated in all FS FMCs and often locked out from being changed on the real aeroplane too, unless you are an engineer and know a few tricks such as simultaneously pressing the same keys on both FMCs to enter various hidden modes on the FMC). The real purpose of derating the engines is so that different models of CFM can be fitted on one (or both) sides of the aeroplane and then matched to the thrust values of the other engine (if they are oddly rated). The 600 series NG is one where this happens, since it has derated CFM engines.Thus you can alter the thrust ratings for both engines, and enter an assumed temperature value too, to get a 'double derated' take off). Note that unless you know what you are doing, this could be extremely dangerous, since you will effectively seriously underpower the aeroplane. Of course in Fs it is not 'dangerous', but you could still bugger up your install, so I would regard this as simply of interest rather than something to try and instead leave those thrust values alone.Some NGs also have an option called 'Bump Thrust', which is where the engines can be pushed beyond the normal values for take off in order to boost the aircraft off the runway using part of the thrust reversing mechanism (since the NG and Classics effectively have slightly vectored thrust from the way the engines are fitted onto it pointing down a bit). This is a customer option only and it cannot be used in conjunction with assumed temperatures. You probably won't see this simulated on an FS 737, although you never know, PMDG might go for it!Have fun!Al

Geez, when you have some free time, how about a detailed answer. :( Amazing stuff, this FS. :( Ray

Geez, when you have some free time, how about a detailed answer. Ray

LOL, well, he did ask. :( Al

Some NGs also have an option called 'Bump Thrust', which is where the engines can be pushed beyond the normal values for take off in order to boost the aircraft off the runway using part of the thrust reversing mechanism

Alan, are you sure about the bump thrust thing involving anything from the reverser mechanism? Sounds more like the software then lets you go into the an "overrated" thrust regime, nothing more. Could be wrong though, but I can't see a use of the reverser apparatus to actually increase forward thrust at takeoff to shorten the to run itself.And fully quoting one of Alan's "short" posts should be prohibited, Ray. :(

Yeah, I agree that it seems kind of weird it would use the reverse thrust system in any way, but that is nevertheless what I've read in the 737 technical guide, so I presume it must be the case since the author does know what he is talking about. Dunno how though, unless it kicks some air down underneath the thing to boost it off the runway, altering the ground effect in some fashion, but that is just a wild &@($* guess. It might instead re-route some of the bypass air in some funky way, like with blown air on the F4 to increase lift, which is another possibility, again, that's another WAG.PPRUNE thread on the subject: http://www.pprune.org/tech-log/251334-thrust-bump.htmlFrom that it seems more like it would be used to reroute air in the manner of a turbocharger, rather than actually using any kind of thrust itself.Al

I have a few components in the fmc which i am unsure which information to enter:The cg, cost index, n1 temperature to calculate thrust (ifly 737ng). How do I calculate this data.

Short answer:CG calculated from the IFly Config managerCI: low number, slower speed, high number, faster speedN1 temp: Guess at it, use a local temp, or just ignore it, the plane will fly fine without messing with it.Of course this is all in the IFly 500+ page manual :-)