Revised landing gear models

[ngomezve]

This PR, which supersedes #107, introduces new landing gear mass models based on historical correlations. In the future, physics-based models could be included as well. The following changes are made:
-Two landing gear models are supported: the previous constant mass fractions and a model based on historical data, which incorporates dependencies on landing gear length and design.
-The landing gear parameters are stored in a new object in ac. The related parg parameters are eliminated.
-Documentation and tests for the landing gear models.

[codecov]

Codecov Report

Attention: Patch coverage is 91.26214% with 9 lines in your changes missing coverage. Please review.

Project coverage is 79.17%. Comparing base (55cd54b) to head (4a63cb9).
Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
src/IO/read_input.jl	57.14%	9 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #128      +/-   ##
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+ Coverage   79.13%   79.17%   +0.03%     
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  Files          82       84       +2     
  Lines       13575    13639      +64     
==========================================
+ Hits        10743    10798      +55     
- Misses       2832     2841       +9     

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[aditeyashukla]

This is a great PR, I think having more complexity in the landing gear models will help us a lot in the long run.
Also, the unpack_ac function is super useful! I know you added it in the main places but we should do a sweep across the codebase and replace it where needed

[askprash]

This looks good, thanks @ngomezve ! Does it give reasonable length of landing gear for the default aircraft? That might be a useful check if we are in the right ballpark. The airport planning docs are a useful place to compare. Looks like for the A321 the main gear is a little under 3 m and the nose gear is about 1.4 m

[argonaut22]

(Haven't reviewed the whole PR yet, but inb4 it gets merged)

I think we're okay to remove the regional and wide regression tests, but I don't agree with binning the hydrogen_sized.jl tests. I think the detailed tests flag errors in the data handling during full aircraft operations that submodule tests would miss. It's fine to nix the regional and wide since the default regression will check those pipes, but the pipes for non-default modules would go unchecked without hydrogen_sized (i.e., fuselage_tank, HX).

See below for less succinct discourse:

[ngomezve]

@askprash For the default TASOPT aircraft (A320-like), I get a landing gear length of 1.17 m assuming a 7inch engine ground clearance. It looks like the A320 actually has a larger clearance. The model currently assumes the same length for main and nose gears, although the data structure allows for them to be different. I'll look if it's possible to make them be different without adding new parameters.

[ngomezve]

If I add one extra parameter for the spanwise location of the main gear (needed anyways as not currently defined) and I change the ground clearance to 60 cm (more representative of the A321), I get a nose gear length of 1.58 m and a main gear length of 1.97 m. This is for the main gear being at 20% of the halfspan as is more or less the case in the A321.

[ngomezve]

The one thing that I am not capturing is that the wing bottom plane doesn't have to intercept the bottom of the fuselage (usually it is further up and hence so is the main gear), but this is probably OK for now.