How does the "asl" and "vac" powers work?

[BrownBoy09]

Ive done a new science mode save, and i am going to attempt to go to minmus. The poodle seems like it would be perfect as a landing/returning to kerbin stage because its super efficient and has 250 thrust in vac. However, it only has 64 in ASL. Would minmus count as Vac because it has low astmosphere?

[GunsForBucks]

Yes the poodle is my go to for minimus

Heck the Nerv motors are good for minimus too since they run just off liquid fuel and the gravity is so low. I use the poodles on my big rovers but my tourist bus uses the Nerv motors.

I even used those little spark engines to land my plane there.
https://steamcommunity.com/sharedfiles/filedetails/?id=2020967692
Good thing as I was coming in on fumes there ha ha. Improved it in later launches though.

[Jupiter3927]

VAC values are what you're going to need for the majority of your travels.
Minmus and most other planets and moons have no atmosphere so any engine with a decent vacuum ISP and decent thrust would work no problem.

ASL is the efficiency at Kerbin's sea level.
Most upper stage rocket engines are designed for space so they take a big hit in atmospheres.
Booster engines like the Mainsail have a much higher surface level ISP but not as great vacuum ISP.

My personal favorite engine to land with is the spark.
It's good pretty much anywhere and it has an amazing thrust to weight ratio that beats out the Terrier.
They work for larger ships too because they're so easy to place everywhere.

[Juggernoob]

In stock solar system, only Kerbin, Duna, Eve, Laythe, Jool (and the Sun aka Kerbol) have atmosphere around them, so yes it's vacuum on the surface of Minmus (there's absolutely no atmosphere).

PS: Duna's atmosphere is not much denser than vacuum though.

[Jupiter3927]

The Sun's atmosphere is extremely hot.
If you somehow manage to enter it, your ship will simultaneously be ripped apart from aerodynamic forces and overheat.

Most engines put out 0 thrust at Jool's surface level.
Something about 15 atmospheres of pressure makes engines not want to run.
Propellers still work though...
Jool would be the hardest planet to launch from if it had a surface to launch from.

Duna's atmosphere isn't enough to be useful but it is enough to mess up your trajectory.
As far as engines care, it's a vacuum.

laythe is basically Kerbin but smaller.
This is the only planet other than Kerbin where jet engines work.

Eve has a thick atmosphere and higher surface gravity than Kerbin so any attempt to launch from Eve is going to need a serious assortment of powerful sea level boosters.
Eve is the hardest planet to launch from.

[Juggernoob]

Originally posted by Jupiter3927:

The Sun's atmosphere is extremely hot.
If you somehow manage to enter it, your ship will simultaneously be ripped apart from aerodynamic forces and overheat.

Most engines put out 0 thrust at Jool's surface level.
Something about 15 atmospheres of pressure makes engines not want to run.
Propellers still work though...
Jool would be the hardest planet to launch from if it had a surface to launch from.

Duna's atmosphere isn't enough to be useful but it is enough to mess up your trajectory.
As far as engines care, it's a vacuum.

laythe is basically Kerbin but smaller.
This is the only planet other than Kerbin where jet engines work.

Eve has a thick atmosphere and higher surface gravity than Kerbin so any attempt to launch from Eve is going to need a serious assortment of powerful sea level boosters.
Eve is the hardest planet to launch from.

That's a great summary!