Open How do I calculate DeltaV in SFS?

[Astro]

In KSP the engineers report, gives you an estimate on how much DeltaV you need. But how is it calculated? How do I calculate it in SFS. I’m figuring that by understanding DeltaV in SFS, I can create more precise rockets instead of making lucky guesses with how much fuel I have.

 

[BANDWITH]

https://jmnet.one/sfs/forum/index.php?threads/the-basics.2583/
The third section of this post, I believe, should help you.

 

[Johnkurveen]

In KSP the engineers report, gives you an estimate on how much DeltaV you need. But how is it calculated? How do I calculate it in SFS. I’m figuring that by understanding DeltaV in SFS, I can create more precise rockets instead of making lucky guesses with how much fuel I have.

Great question! I think calculating deltav is really important to good rocketry design. Try that thread and if you have any questions about it, feel free to ask.

 

[Blazer Ayanami]

In KSP the engineers report, gives you an estimate on how much DeltaV you need. But how is it calculated? How do I calculate it in SFS. I’m figuring that by understanding DeltaV in SFS, I can create more precise rockets instead of making lucky guesses with how much fuel I have.

Ln(wet mass/dry mass)*G*ISP

 

[Altaïr]

Here is a simple calculator for this:
https://docs.google.com/spreadsheet...zOEbB5pSJMOjeiR-ES4y0HOzxy8/edit?usp=drivesdk

(It's in read-only mode, you have to make your own copy to use it)

Here is how it looks like:


On the left, just specify how many of each engine you use. Ignore the "unused" column.
On the right, specify how many tons of fuel tank you have, and the dry mass of remaining parts.
This is the only tricky part, you must not include the engines and the fuel tanks in dry mass, they are already accounted for.
Then in the blue tables below, you have everything you want to know.

For example, if your ship is compound of a broadsword, a 20 tons fuel tank, a capsule and a parachute, you will enter:
- 1 broadsword in engine specs
- 20 tons for fuel tank
- 4.5 tons for dry mass (capsule + parachute = 4.5 tons)

As you see it's very simple, but it only works for a stage at once. If you have upper stages, you have to include them in dry mass.