How accurate is SFS's Physics?

[Realistic Mods]

Sometime ago, I was trying to make a high Isp engine in SFS by reducing the height of the Valiant engine (since it was my observation that increasing height increases Thrust, but reduces Isp, and doing the opposite does vice versa). In order to calculate the engine Isp, I decided to send it to moon, burn the engine till flameout, and use the rocket equation, in a zero air resistance environment. It was then that I wondered if SFS's Physics were indeed accurate. You know ,a circular Low Earth Orbit with a altitude of 150 km has a velocity of around 7-8 km/s. If you orbit at the same altitude in SFS, its much less, even with the presence of a gravity of 9.8 m/s^2. So can someone clarify?

 

[Altaïr]

(since it was my observation that increasing height increases Thrust, but reduces Isp, and doing the opposite does vice versa).

I thought that stretching engines changed thrust but not the Isp... I may be wrong though, I never do that.

In order to calculate the engine Isp, I decided to send it to moon, burn the engine till flameout, and use the rocket equation, in a zero air resistance environment.

There's actually a better way to do that: activate "no gravity" and "no drag" (probably "no heat damage" too), and launch straight up from the pad

It was then that I wondered if SFS's Physics were indeed accurate. You know ,a circular Low Earth Orbit with a altitude of 150 km has a velocity of around 7-8 km/s. If you orbit at the same altitude in SFS, its much less, even with the presence of a gravity of 9.8 m/s^2. So can someone clarify?

This is perfectly correct. SFS physics are accurate, the reason why the orbital speed is that low is because of scale: SFS' solar system is really tiny. The Earth's radius is only 315 km (instead of 6400), there's approximately a factor of reduction of 20. That's why the orbital velocity is that reduced. Actually, it makes reduce speeds by a factor sqrt(20), so approximately 4.5.
If you play in realistic mode however (if you have the PC version...), you will notice that the orbital velocity has the expected value.

 

[Realistic Mods]

So, does the Rocket equation work for SFS rockets?
And actually I am a no dlc player, so moon was the only option for me. Thx for replying!

 

[Altaïr]

So, does the Rocket equation work for SFS rockets?

Yes, absolutely.

And actually I am a no dlc player, so moon was the only option for me.

Ah, I didn't think about that. In this case the Moon is a good option indeed.

 

[New Horizons]

bro just got into a nice conversation with him