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Initial altitude exceeds max. alt.


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Hi,

 

I've been trying to make a file for the Socata TB20 "Trinidad".

Everything seemed fine untill I got the message: : "Initial cruise altitude (FL120) exceeds maximum altitude"   over and over again. (See attached picture).

Maximum altitude is set to FL200, as it is in the real aircraft.

I'm only able to compute the flight if selecting "max altitude" as initial cruise altitude.

But then the flight takes about 4 hours, instead of 2. The initial altitude indicated: -1ft

 

I think it's just a stupid error from my side, but I'm not able to find it by myself.

If someone needs more information or screenshots I'll upload them asap.

 

Regards,

 

Richy

 

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Hi,

Show your aircraft file. Maybe you are referencing to a wrong aircraft type. You are showing here only the type file but not the actual aircraft file in use. It should be the PH-MLL.txt file.

Rgds

Reinhard

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Hi Richy, are you creating a performance file for the TB20 from scratch? In that case we'd need to see the actual .txt file itself to see if there's an error in the data format. If you attach it to a post that'd be the best way to get help, or if you'd prefer you can PM me. I'm away travelling for a couple of days with only an ipad, but I'm sure there are other folks who could offer help. Jon

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Richly, I don't have a laptop so can't run PFPX, but there's only data present up to 12,000ft. Best will in the world but I can't see how PFPX could correctly plan up to 200 if there's no data available to it.

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Forgot to mention I just changed the certified ceiling from FL120 to FL200, since I only fly the real plane without oxygen (+due to the lack of a turbo). But with certified ceiling FL120 the same error occured. 

The only difference compared to the SR22T.txt file I see are the isa-10 and isa+10 cruise figures. But Socata doesn't have those figures included in the POH.

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Gents,

 

Somehow the TB20.txt file is working fine in PFPX now. I didn't touch the certified ceiling anymore (so it's still FL200 now), but instead I'm using the "altitude/FL capping" function inside PFPX. Till now it works fine.

In fact, I didn't change anything in the text file.

I'll inform you when bugs are found.

 

Feel free to use and/or modify the file, since Flight1 is releasing the TB20 "soon":D

 

Many thanks for your support!

 

Richy

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For the ones who wanted to use the file, I've corrected the fuel capacity and added a LRC option.

Socata TB20.txt

 

EDIT***

 

I'm still getting the error message every now and then. FL090 is the max I seem to get out of it at some routes. I'm using the latest navigraph and all the MEAs & MAAs are checked and validated.

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Hi,

This section is wrong:

[DATA]
   ISA;   3086             
   MAX;   20000
   OPT;   9000
 


 

It should read like this:

[DATA]
   WGT;   1400
   OPT;   9000
   MAX;   20000

 

Weights must be in KG as configured and OPT must be befor MAX. As the link to the PDF in this forum doesn't work anymore, I had to find it out by trial and error. Maybe the admins can repair this link:

Wrong link

Topic

 

Rgds

Reinhard

 

 

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Good catch! Or a stupid error from my side :P

So you didn't get the same error as me, since you were talking about trial&error?

 

I'll test it asap and I'll let you know.

EDIT***

 

That seemed to be the problem! I can even enter FL190 now! PFPX doesn't even have the performance figures for those altitudes:lol: 

 

Many thanks!

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Hi,

 

I found now the describing document. I have luckily archived it on one of my harddisks. I upload it here for reference. It was done by user BW901. Many thanks for it.

I got the same error as you when I used your template. Then I selected MAX and I found, that PFPX was not planning higher than FL80. Then i compared your template to others and then I saw the difference.

 

Rgds

Reinhard

 

PFPX Aircraft template Notes.pdf

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Richy,

I think Reinhard has covered the obvious points but for what's it's worth my summary of what to look out for are:

1. Do not mix KG and LB. They must be constant throughout the profile, for both aircraft weight and fuel burn.

2. I don't know how PFPX works if you provide data up to 12000 and then tell it your max altitude is FL200? It's got nothing to iterate between above 120, I would suggest you limit the PFPX envelope to 12000 feet if that's the only data you have.

3. There are 2 ways PFPX handles cruise data. First is to only include ISA data and then provide an adjustment, the second is to provide data for different ISA variance. You've gone down the first route, but in that case I think the first line after the [DATA] tag should start "   WGT;" rather than "   ISA;". If you've got no data below 2000ft (the TB20 manuals available online provide climb and cruise from 500ft to 12500ft) you don't need to include the MinCruiseAlt and CruiseModeBelow flags, as there's nothing for it to reference.

4. For descent I'd strongly suggest that the data lines run from ground up, so the 2000ft data first, up to 12000ft. I know some of the profiles bundled with PFPX have descent tables with decreasing altitude, I have found that this can cause problems. If everything, hold, climb, cruise and descent has altitude data in increasing values it seems to work fine.

Finally I'm not sure how PFPX works with data for just a single weight value. Personally I'd do a "dummy" weight at min weight as well (same values as the max weight data) you've included. That way at least PFPX is able to "iterate" for the full weight range, even if there's no actual change in performance as the weight changes. This may be over cautious but you know 100% that PFPX is actually calculating based upon your instruction.

I must take a look at that old guideline note that I wrote a couple of years ago, and improve and expand it! Thanks Reinhard for digging it out.

Jon

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