Flyout

Here is an excerpt from Flyout's Steam description:

Flyout is an aircraft building game with an emphasis on design freedom and realistic physics, sound and effects. Use the in-game modeling tools to create an aircraft of any shape, add and configure engines for your needs, set up control surfaces and take your design on a test flight around an earth-sized procedurally generated planet.

Simulation

• wing shape, span and sweep have a large effect on flight behavior
• fuselage drag is calculated from shape
• engine simulation
• aircraft sounds change with design
• realistic atmosphere model
• wind, turbulence, vertical draft
• ground effect

This game is not easy. There are no in-game tutorials and tool tips are limited due to Early Access status. Fuselage editing is similar to modeling in any 3D software, although much simplified. There will be bugs due to the highly unrestricted editor and Early Access status of the game. Basic understanding of aircraft physics and flight controls is required or at least recommended.