Aircraft.cfg Jet engines and adjustments N1 N2 ratios

[Jetblst 23]

Ok,

 

So I have got the hang of Fuel Flow Scalar, Thrust Scalar, Inlet Area etc.  I finally have the Engines on my Beechjet running like they do in the RW aircraft.  Fuel flow, Spool up, etc.

 

The one thing I cannot seem to tweak is the N1 N2 Ratio.  Right now they virtually mirror each other (in sim)  which simply is not the case in reality.  

 

What needs to happen is that N2 should not be spinning near as fast as N1 see photo.

 

 

Is or are there any edits I can make in the aircraft.cfg file?  Or is this an air file thing?

 

Thanks so much.

[Mariopilot 9]

Hi!

 

N1 vs. N2 and their idle/max values are .AIR controlled.Since Aircraft.cfg can only control rated N2, be sure to match it in the.AIR or great confusion is created as to what the actual idle value is...

TBL 1502 should do the trick. Also, note that you are likely going to affect thrust output!!

[Jetblst 23]

So if I understand you right, they may effect thrust output but I could then go back and re visit or re work the adjustments I made in the Aircraft.cfg file, however Id be then close to all the parameters I am looking for?

[vololiberista 205]

You need to study tables 1502 to 1507 in the air file. You say you have sorted the spool up time. Have you done that in table 1505? If that table has a convex curve it's wrong.

When that is correct go on to tables 1503 and 1504 to sort out your cn2. Then adjust your cn1 to the cn2 numbers in the other tables. For all this you need performance tables for the engines and also engine limitation tables.

Bear in mind that n1 will catch n2 up as the engine accelrates.

[Jetblst 23]

Ok

 

I sorted out the spool up time via the Aircraft Config.  It was close to the real aircraft so no further need to adjust that.

 

Not sure what you mean by convex curve.  Did you mean via Air Wrench?

 

I did about as much trial and error as I could via Air Wrench.  

 

I just downloaded a fairly good copy of AIRED.  I am starting to see what you are talking about.  

 

I have cruise, power, fuel, etc Real World charts for the Beechjet as I fly it professionally.  

 

My main goal here is not to re-engineer things but simply to adjust N2 while having N1 behave properly.  May not be able to be done.

[vololiberista 205]

Ok

 

I sorted out the spool up time via the Aircraft Config.  It was close to the real aircraft so no further need to adjust that.

 

Not sure what you mean by convex curve.  Did you mean via Air Wrench?

 

I did about as much trial and error as I could via Air Wrench.  

 

I just downloaded a fairly good copy of AIRED.  I am starting to see what you are talking about.  

 

I have cruise, power, fuel, etc Real World charts for the Beechjet as I fly it professionally.  

 

My main goal here is not to re-engineer things but simply to adjust N2 while having N1 behave properly.  May not be able to be done.

I prefer aired to airwrench as it is less complex. Before you do anything to n1 you must get CN2 correct. For a convex curve in 1505 think of a surfer's favourite wave tube. It looks a bit like that. Then table 1503 start with your throttle values and then calculate cn2 for different altitudes. Then in table 1504 calculate the cn2 values for mach.  Do a search for how to and you'll find long discourses on how to do it. It's complicated to get it right. Only when you've got cn2 correct move on to n1.

[Jetblst 23]

LOL

 

Ya I saw some of your posts over on FS Developer.  It does look complicated.

 

Ok.

 

On Aired I was doing great until I went back for a second look and everything came up unknown.  Any ideas why?  All the numbers were in HEX etc.  ??

 

Im a complete newb at this but I have to learn somehow.

 

Hopefully the searches will reveal what I am looking at, what the numbers mean etc.  Thanks Vololiberista

[vololiberista 205]

LOL

 

Ya I saw some of your posts over on FS Developer.  It does look complicated.

 

Ok.

 

On Aired I was doing great until I went back for a second look and everything came up unknown.  Any ideas why?  All the numbers were in HEX etc.  ??

 

Im a complete newb at this but I have to learn somehow.

 

Hopefully the searches will reveal what I am looking at, what the numbers mean etc.  Thanks Vololiberista

Sounds like you just pressed the wrong key. Editing aired is a slow process bit by bit. So it's a bit tedious. But, you can see where you are. From those posts on FSDeveloper and others you can see that it is not a simple undertaking. Do a spreadsheet with the calculations and graph it so you can see what the curves look like before putting them into the air file.

[Jetblst 23]

Nope not simple at all.  But looks fun!  If one can call it that.

 

My search so far has only turned up debates about who is right and wrong etc not too much by way of this is how...

 

I have plenty of data already as I have taken notes and photos of the N1 N2 relationships during actual flights at all altitudes etc.  Plus I have cruise charts 

for the aircraft as well as my own notes of fuel flow and power settings down low (5,000) etc.

 

Is there any documents that define what each number means?  I have the flow chart and explanation from Mudpond.  I get the big picture.

 

What would be useful is to know what the numbers mean in each array. 

 

Again I am a newb here and not a programmer or engineer so Im not at that point to sit down and toss in equations.

 

Thanks a lot for your tips though.

[Jetblst 23]

Hmmm  Ive had a little success.

 

What I did was I figured out how to update the airfile.  I found using Mudpond Airupdate helped but ultimately Aired is easiest now that I know how the numbers must be formatted

 

So I used 96% for all numbers in my 1503 and 1504 files where the existing numbers were over 96%.  I know this is incorrect.  BUT, it DID limit my N2 to 96%.

 

That was positive.

 

Now to figure out the rest.

[vololiberista 205]

Who is right or who is wrong? What you must do first is to establish your n2 throttle relationship in ISA sea level conditions. Extend that to cn2 at given altitudes using the correct formulae. Again using additional formulae create table 1504 which is cn2 v mach. Once you're happy with those numbers you can then begin to calculate the relationship of cn1 to cn2 referenced in the other relevant tables. The given formulae are correct.

[Jetblst 23]

ok thank you.

[Jetblst 23]

Hi!

 

N1 vs. N2 and their idle/max values are .AIR controlled.Since Aircraft.cfg can only control rated N2, be sure to match it in the.AIR or great confusion is created as to what the actual idle value is...

TBL 1502 should do the trick. Also, note that you are likely going to affect thrust output!!

 

That was correct 1502 did do the trick for N1.  I was able to finally get N1 to produce 104% on takeoff.  That is what the EFC computers do.  I still had the problem with N2.

 

What I did was to go through and start setting numbers to max N2 output of 96% or at least that is the limitation.  In my RW experience I dont see it get close to that.

 

Anyway I was able to set 1503 and 04 up with 96% at max throttle settings.

 

 

This was probably not the prefered way, but it works.  I also have my aircraft config setup correctly too so that the aircraft handles almost like the real thing.  VERY close now which is ultimately what I wanted.

 

Still working out high altitude parameters but so far everything is close.