Takeoff Distances

[Brian Metcalf]

Does anybody else have issues with the takeoff distance calculations?  

0' pressure alt, 30°C, 2200lbs and 0kts wind gives me 760 roll and 1335 over 50' obstical

0' pressure alt, 30°C, 2197lbs and 0kts wind gives me 946 roll and 1700 over 50' obstical

Something seems off with the calculations.

[Jeffrey Ross]

Let me ask a question first, what should the T/O roll distance be and the distance to clear the mythical 50ft obstacle in your examples? 

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[Brian Metcalf]

The data for 2200lbs is correct to the performance data in the POH.  I would think the 2197lb info being only 3lbs different should be very close to 760 and 1335 instead of being vastly different...

I used the C172S to create the profile for my aircraft and added the custom numbers from my POH into the system.

[Apps4av Support]

Please send your database file and will check

Regards,

Apps For Aviators Support,

We encourage users to use the Forum for all questions. Any updates to the forum will help other users, who might have similar questions.
Forum: https://groups.google.com/forum/#!forum/apps4av-forum

To view this discussion visit https://groups.google.com/d/msgid/apps4av-forum/b0f7e540-1d8f-4ffd-bc53-ea775dc7c065n%40googlegroups.com.

[Brian Metcalf]

Are you talking about my POH or a database file from AvareX?

[Apps4av Support]

The database file which appears under documents as user data. If you are using the default aircraft then you don't need to and I can look. But if you have customized it then I need the database 

Regards,

Apps For Aviators Support,

We encourage users to use the Forum for all questions. Any updates to the forum will help other users, who might have similar questions.
Forum: https://groups.google.com/forum/#!forum/apps4av-forum

To view this discussion visit https://groups.google.com/d/msgid/apps4av-forum/28716432-5da4-4c32-a28e-776db70d8f0cn%40googlegroups.com.

[Brian Metcalf]

I attached the database file.  Let me know if you need anything else.

[Brian Metcalf]

As I play with it some more, I've added the full POH numbers for all altitudes and temps available (uploaded new user.db).  If I only have 1 of 2  not match the table I get a result I expect.  If I make more than 1 not match the table numbers I get an unexpected result.

alt        -     temp     -     lbs        -     distance

1000   -     30          -     2200    -     830    -    Book Number

1000   -     27          -     2200    -     814

990     -     27          -     2200    -     982

990     -     30          -     2200    -     829

990     -     30          -     2205    -     831

990     -     27          -     2205    -     983

1000   -     30         -      2300    -     923

1000   -     27         -      2300    -     1007

990     -     30          -     2300    -     979

990     -     27         -      2300    -     1006

1000   -     30         -      2400    -     1015    -    Book Number

1000   -     27         -      2400    -     994

990     -     30          -     2400    -     1014

990     -     27         -      2400    -     1035

On Friday, April 24, 2026 at 4:52:28 PM UTC-4 app...@gmail.com wrote:

[Apps4av Support]

There is an error in your tables: alt=5000, temp=0, weight=2200 appears twice, with values 965 and 1295 

But regardless, I am working on improving the interpolation.

To view this discussion visit https://groups.google.com/d/msgid/apps4av-forum/d1308cd2-f914-4db7-80b8-7a5960cbac5an%40googlegroups.com.

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[Brian Metcalf]

I was pulling the source and going to help out with this and realized you had already pushed updates for this.  I went through and compared it to another app I have and am getting really good numbers.  Awesome job on this!