More exact formula for density altitude calculation

Akaflieg-Freiburg / enroute

A free navigation app for VFR pilots

https://akaflieg-freiburg.github.io/enroute/

GNU General Public License v3.0

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More exact formula for density altitude calculation #452

Closed Munzijoy closed 3 weeks ago

Munzijoy commented 1 month ago

I read about the discussion of adding a density altitude calculation and, based on https://github.com/charlylima/enroute/tree/feature/densityAltitude I implemented the more exact formula, according to issue comment https://github.com/Akaflieg-Freiburg/enroute/issues/408#issuecomment-2067600299 I also added a dry air approximation, in case for whatever reason, the dew point is not present in the METAR.

The formulas described in https://aerotoolbox.com/density-altitude/ have been used. Note that on that website, there are errors in the formula for Herman Wobus approximation (odd polynomial coefficients lack minus signs).

kebekus commented 1 month ago

@Munzijoy Thank you so much! I look at this as soon as possible, probably early next week.

kebekus commented 1 month ago

@Munzijoy @charlylima Dear all, I quickly looked at the PR. I want to merge it, but a few things need to be done. Could you please have a look at the following items?

In the class DensityAltitude, most methods take doubles and return a double. To lower the potential for error, would it be possible to use the appropriate classes from the "Units" namespace.
I am unsure if there is duplicated code between the classes DensityAltitude and Atmosphere. Could you please have a look?

Again, thank you for your contribution! If you want, I can do the changes myself … but I will definitively need some time for that.

Best,

Stefan.

Munzijoy commented 4 weeks ago

In class DensityAltitude I will replace those double return values and parameters by appropriate types from the Unit namespace this week.

For the Atmosphere class I checked for duplicate code, but only found similar, but simplified code / formulas, as the ISA model is a simple static atmosphere model. Therefore the density formula in the Atmosphere class only takes dry air partial pressure into account. The only duplicated code are some physical constants (but defined as local variables).

kebekus commented 4 weeks ago

Thanks! I will merge this PR and streamline the code a little. However, I am drowning in mail right now, so please give me a few days.

kebekus commented 3 weeks ago

@Munzijoy @charlylima, I have merged your pull request into the branch "feature/densityHeight" of the main repository. For the next few days, I plan to streamline the code a bit and then include it in the next release. Thanks again!

kebekus commented 3 weeks ago

@Munzijoy @charlylima We list all people who have contributed to Enroute as "active authors" or "alumni." I would be more than glad to include you. Please let me know if you are happy with that, and if so, please tell me the following.

In which category would you like to be listed? - Active authors are active and become alumni after one year or so of inactivity.
Your real names. For active authors: a sentence or two describing yourself.

Are you also interested in joining our GitHub team?

Thanks again · Best wishes,

Stefan.

Munzijoy commented 3 weeks ago

Thank you so much for the offer. I appreciate it a lot and would really like to be mentioned as an active author - and would also like to contribute further in this great app.

My name is Tom Linz and I just got my PPL license a couple of days ago. I've always been interested in aviation and now made that dream come true. I work as a development engineer for safety systems.

Joining the team would be great.

kebekus commented 3 weeks ago

@Munzijoy We'd be delighted to have you in the team. I just sent you an invitation via GitHub.

kebekus commented 3 weeks ago

Closing this PR now because the code has been merged into the main repo.

charlylima commented 3 weeks ago

Hello @Munzijoy I am happy that you finished it ! Great work!

charlylima commented 3 weeks ago

Hello @kebekus I would be happy to be part of your team. I would like to help with some topics, e.g. GPS logging, automatic logging of start and landing time, export route in flight plan format. I hope i will have more time to work on it in the future.

I am currently working on creating a "development docker" that has Qt and the dependencies pre-configured for easy compilation. You can even use the docker container to launch the Linux development environment on MS Windows with WSL2.

Christian Engelhardt, PPL pilot in southern germany, studied electrical engineering and working as an Embedded SW Engineer.

kebekus commented 3 weeks ago

@charlylima Welcome! I sent you an invitation via GitHub to join the Akaflieg group. I also added the text about you to the development branch. Your code will likely appear within the next two weeks, in version 2.31.17.