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Which tool for take-off performance calculation?

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Garbage In - Garbage Out is always a problem in writing expert system programs such as this. An expert system is a rules based model of the problem you're trying to solve. The programmer can limit inputs to the "relevant range" of acceptable practice but then if it changes the program is obsolete or needs to change the assumptions. The alternative is to write in an "expert" option but IRL, everybody's an expert and we're back to gi-go. When writing programs for true expert users I opt for a combination of both that queries the user for an input but warns him/her when and if something's a little "off". You know - something like "Are you completely out of your fricken mind? Just exactly how many passengers do you want to kill?" will usually give 'em a heads up.

 

As far as how much information to present in your output fields it again depends on the level of interaction you're expecting from the user and whether or not he/she is expected to manually verify the results being presented. If the program is being used in a time critical section of flow then "management by exception" is appropriate. MBE highlights or presents only that information requiring attention from the user. Presenting date in green for good or red for danger is an example.

 

Many expert systems are used in optimization decision making known as parametric sensitivity testing. The program uses a range of inputs and prepares a solution matrix that can show all possible solutions or limit itself to only those solutions that fall within a relevant range of acceptable or standard practice. Instead of looking at a snapshot of the problem, the program runs a movie. The truth is though - unless your qualified through training, education or practice to make the decision promised by the software, you shouldn't be using it in the first place.


Rick Bertz

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I don't like topcat. No sense in calculations! using utopia v1.2 and waiting for aurasim! in only use topcat for the NGX and nothing more


Jason Cardeira

Banner_FS2Crew_Beta_Tester.jpg

 

 

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It's not as accurate as it should be, but I wouldn't throw it out entirely.  It gets the job done for now.


Kyle Rodgers

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For now, if you want just for 'enough' data for takeoff rather than 'extremely precise' one, I'd recomment get used to manual calculation using 'the documents'..

 

I really tried hard to understand takeoff performance recently, but all the methods results different output.

Manual calculation using FPPM, the excel sheet for 777, Utopia.. All different output with same data.

(Utopia is based on 'experience' record according to readme file in it - so I think it is generally acceptable for PMDG, too.)

 

But ultimately, I realized that with these calculations(including FMC calculation that does not care about RWY length), there's no way to get perfect V speeds without getting TODR, ASDR.. (maybe I'm wrong at some part of this..)

 

So if you want a 'complicated result' with 'simple' method, TOPCAT is your answer.

(But I doubt that buying this program is worth for everyone because the update for their whole product  is a little bit slow.)

 

I do use manual calculation, and double check with Utopia when I fly T7. Both two results have no big differences, so I'm happy with this. (I know the actual V speeds will be less than these values but it is acceptable for me..)

 

Hope this helps you to decide.  :lol:

(If my English is readable though  :wacko: )


Peter Chang

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Thanks for the additional information guys. I went for TOPCAT. I tried UTOPIA but got inconsistent results.


- TONY -
 

 

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Is Topcat still supported?

I don't believe anyone knows. I know it's not supported by the TOPCAT Forum since it has been a read-only forum as of Jan 2015. Support tickets can be submitted here - http://flightsimsoft.com/support/. Maybe you will receive a reply. I think TOPCAT is dead in the water. What you have is what you are going to get.


Michael Cubine
xVxT6x.jpg

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TOPCAT only has a 'beta' profile for the 200LR/F, no 300-ER. 

 

For what it's worth, I have access to a real world 777 EFB (300-ER/F/200-LR in GE and RR engines) and have tested it against both the TOPER and TOPCAT calculators. The results varied wildly, as you might expect. The TOPCAT one spat out the most accurate results in terms of speeds and margin but the derate N1 figures were a long way off and were up to 10 or 15 degrees lower than the real one. Using these figures we managed to drag the gear through the lights at Dublin on the departure - whoops. 

 

The 777 FMC automatically generated V speeds are incredibly accurate however, within a knot or two of the Boeing EFB for 'balanced' field conditions. Great job, PMDG.


airline2sim_pilot_logo_360x.png?v=160882| Ben Weston www.airline2sim.com 

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In several cases at EDDF in the 777F with at TOW of about 650000 lbs. TOPCAT has returned flaps 5, D-1,assumed temperature of 30 and a margin of about 2000 ft. Enter D-1 and 30 on the thrust limit page and flaps 5 on the takeoff page and the FMC will not provide any V-speeds. Sometime TOPCAT is totally out to lunch.


Michael Cubine
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Is Topcat still supported?

The fact that the 777 data is still beta and still incomplete tells me it's not being worked on. It seems a shame to abandon such a good product, especially as it links with PFPX.

ki9cAAb.jpg

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I looked for "Topper" and was reminded of a TV show I forgot all about from my early childhood.  Finally found Toper at SimMarket and careful review of product revealed that it doesn't do fixed derates (TO1, TO2)...., well that isn't worth 10EUR. I guess the best thing going is Topcat to get you in the ballpark then the FMC as a final check.

 

I've been using Topcat for about  a year and it's mostly in the ballpark, as for B77W I just use the 777F calcs. Too bad there's nothing better.


Dan Downs KCRP

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I looked for "Topper" and was reminded of a TV show I forgot all about from my early childhood. Finally found Toper at SimMarket and careful review of product revealed that it doesn't do fixed derates (TO1, TO2)...., well that isn't worth 10EUR. I guess the best thing going is Topcat to get you in the ballpark then the FMC as a final check.

 

I've been using Topcat for about a year and it's mostly in the ballpark, as for B77W I just use the 777F calcs. Too bad there's nothing better.

It does do fixed derates now. They haven't updated the product description


~William Genovese~

  Boeing777_Banner_Pilot.jpg         KAB200_sig3.jpg

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It does do fixed derates now. They haven't updated the product description

I do not have Topper yet, but I had a quick look at their support forum and the developer looks to be active and updating. That is a good sign. Having all variants of the 777 and 737 and only 10 usd each is very fair and I plan on buying it soon. Nice to have 739 and 773 profiles, Topcat does not have these. I did notice in my years of using Topcat it is obsessed with flaps 5 no matter your weight so I always did flaps 15 and it put out realistic numbers. Will hold me over to buying Topper in the next month or so. - David Lee

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