Jump to content

[Web] kspalculator - Determine Best Rocket Propulsion Designs (i.e. Engine and Fuel quantity) for given Constraints


Recommended Posts


during the past weeks, a friend of mine and I created kspalculator. kspalculator is a tool written in Python3, which determines the best rocket propulsion designs for one stage of a rocket, given a set of constraints and preferences.

Constraints are properties of the spacecraft which have to be fulfilled. These are the possible payload and the Delta-v as well as the minimum acceleration which is reached in an environment with given air pressurePreferences are further properties a propulsion design might fulfil in order to be preferred. Examples for preferences are the thrust vectoring angle, the radial size, whether the engine is able to generate electric power, etc.

Which is the best design depends heavily on the specific application. A design might be better than another one, if it is cheaper or has a lower mass, but it might also be considered better if it is buildable using less technology or if it better fulfills some of the given preferences. Obviously, it is impossible to sort all propulsion designs by their "goodness", so there might be more than one which is the best at least by some criteria. This tool presents exactly all best designs.

The stage might have different requirements for minimum acceleration for different flight phases through different air pressures and different Delta-v requirements. For example you might require the vessel accelerating by 1000 m/s with an acceleration of 3 m/s², and later 500 m/s with an acceleration of 7 m/s².

Besides considering the classic liquid fuel engines as well as solid fuel boosters, kspalculator also considers using the LV-N Nerv Atomic Rocket Motor, the IX-6315 Dawn Electric Propulsion and the O-10 Puff MonoPropellant Engine.

Even though calculating this sounds highly sophisticated, the best designs are presented to the user usually within less than a second. The information shown about each design includes a detailed listing of the performance characteristics, i.e. the actually reachable Delta-v (which might be slightly more than required, because of rounding to tank sizes), the acceleration at full thrust as well as the mass at beginning and end of each flight phase.

By the way, it is compatible with the latest version of KSP, 1.2.1!

You may get more information and download kspalculator at:


Additionally, there is a web application at:


Edited by aandergr
Update supported KSP version
Link to comment
Share on other sites

  • 2 months later...
  • 2 months later...
  • 4 weeks later...
This thread is quite old. Please consider starting a new thread rather than reviving this one.

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Create New...