Issue with 777 and Topcat (N1 discrepancy)

[Airline2Sim 489]

I'm afraid TOPCAT ain't up to much for performance with the T7. 

 

The real Boeing OPT says for your takeoff:

 

V1 175

VR 180

V2 180

 

SEL TEMP 54C

 

%N1 91.8 for TO, I don't have the numbers for TO2.

 

TOPCAT gives:

 

163/169/173

 

46C

 

97.7%

 

Miles out! 

 

PMDG's 92.1 N1 setting is pretty much on the money, however.

[Mephic 129]

Thanks Ben. 

I'm sure I would be unhappy if I bought it specifically for triple 7, fortunately works for NGX like a charm. 

I am going to look into TOPER calculator as I plan to get 300 expansion anyway and TOPCAT didn't cover it. Hope they did it better. 

[whoispankaj 51]

You guys should really make a performance calculator... And the mobile/iOS/Android version tooo...

[pcubine 143]

I use TOPCAT to get in the ballpark as far as assumed temperature, derates, flaps and margin are concerned. If there is enough margin left I will enter the temperature, derates, and flaps into the FMC. If the V speeds are close, I am satisfied. I use the V speeds calculated by the FMC. I don't even look at N1.

 

The current version of TOPCAT is 2.74. Development on the product has stopped and I don't believe it will ever be resumed. There are no "newer" profiles for TOPCAT. What comes with the Program is the end of the road.

[Airline2Sim 489]

Thanks Ben. 

 

I'm sure I would be unhappy if I bought it specifically for triple 7, fortunately works for NGX like a charm. 

 

I am going to look into TOPER calculator as I plan to get 300 expansion anyway and TOPCAT didn't cover it. Hope they did it better.

 

In fairness to TOPCAT they did only ever say the 777 profile was beta. TOPER is not exactly on the money either, from the testing I've done.

[ILYUSHIN_IL62 0]

Yeah it's too bad, such potential with that program.  I guess there is no profile out there for the -300ER is there?

[thepilot 562]

Haven't flown the 737 in a while but I recall there's a slight discrepancy in the N1% as well.

 

What is the best solution to get around this? I now try to match the N1%, but may use a different ATM (e.g. +40°C in TOPCAT and +45°C in the FMS to get the same value), as I think that is what counts.

 

If you ask me, what is really missing from PMDG addons is some sort of comprehensive peformance calculator.

[downscc 1,327]

 

 

If you ask me, what is really missing from PMDG addons is some sort of comprehensive peformance calculator.

 

I agree, and I've read comments from one of the developers musing how he would like to do that but they are been very busy with new products.

 

As for matching N1...., just take what TOPCAT offers with a grain of salt.  It is not a professional product whereas the NGX was developed based on Boeing licensed data.