Hi Leonim!
I though this topic will just die out therefore I am so happy to see your input.
I am totally new in this game but not is physics whatsoever. Although aeronautics is not my domain I checked if the developers did not adopt some of the well known physics. Well, it turned out they did and I am happy to share my findings.
So far I did a calculations for wing size m and if aircraft have only these than sustentation speed can be calculated as of function of:
- percent of atmosphere [%]
- aircraft weight [t]
- amount of wings []
- gravity [g]
The equation goes:
Sustentation speed [m/s] = SQRT(((gravity * aircraft_weight * 1000) / amount_of_wing_m) / (percent_of_atmosphere * 50,1))
Therefore if:
- Ship weight is 140 tons,
- Gravity is 9,8 m/s
- Atmosphere density 100%
- 4 wings M
Sustentation speed is - 82,83 m/s
Accuracy is circa +/- 2%
Therefore at 10% atmosphere and 0,9g gravity sustentation speed for the same ship is 248,48 m/s. That also answer the question - "what should be my max speed to get off a planet" in the way that "your max speed should be above 248,48 m/s to leave the planet". If you load 40 tons of cargo it becomes 281,75 m/s. Pretty handy equation. I will develop it for more wing types.
Speaking of engines. Engine_thrust(atmosphere_density) function is linear. They also use air resistance which is also linear to atmo density. This is how they keep max speed regardless of altitude. You can notice it by travelling at high attitude - you will experience same speed but your fuel will last for many times longer. In other words - with 50% atmo density you will consume twice as much fuel with the same speed than at 25% atmo density. So as long as you fly horizontally all is good. I see 10% error but I am 95% sure relation is linear. That may be due to low amount of data,
Once you want to increase the altitude at high altitude a ship begins to behave totally different than in low altitudes. At 10% of atmo thrust is just 10% and wings are key lift force here. At low altitude, with thrust 2 g you can start easily and high rising angles don't kick back (engine is strong enough so if your lift drops due to high angle you are still good as engine is stronger than gravity) but at 10% atmo the thrust goes from 2 g to 0,2 g so high angles make you fall easily even with small angles. From what you wrote I guess you are pretty comfortable with vectors and trigonometry so I will skip the explanation. Keeping a high speed and low angles is therefore essential at high altitudes. As in the equation above, at 10% atmo sustentation speed of 140 tons ship with 40 tons of cargo is 281,75 m/s. Lower max speed will not allow you to reach the space engine activation altitude. Also if your speed during ascending will drop below 281,75 m/s (at 10% atmo) you will see your ship falling. It is also how my equation and max speed shown in construct can answer the question - "will I reach space?"
On top of that I found out that these guys are geeks. I love it! It must be fun to work there.
P.S.
In real life air resistant is proportional to 3rd power of speed. So increasing speed by 10% will increase the resistance by 33.1% I assumed such a relation at a beginning and it took me w while to figure out why things are not adding up. Assumption that fuel consumption is linear to thrust actually helped me to solve it. It is still an assumption though.
