StageSummarizer

[Searcher Space Agency]

So,I was working on python and coding some calculations; I thought why not make a stage summarizer? The thing I mean by "summarizer" is it wants some data from a stage of your rocket and makes a list of it with adding some of its own with the calculations.

If that ^ sounds weird I'm sorry for my English.

Currently only for pc(windows I guess)

 

[Astatium_209]

This is pretty cool, but you should specify the accepted units of wanted data. It told me that my rocket consisting of a 3t probe, Valiant and 15t fuel tank has a delta v of around 7000m/s , it should be around 3000 m/s, but that's probably just me making mistakes while inputing the info...

 

[Searcher Space Agency]

This is pretty cool, but you should specify the accepted units of wanted data. It told me that my rocket consisting of a 3t probe, Valiant and 15t fuel tank has a delta v of around 7000m/s , it should be around 3000 m/s, but that's probably just me making mistakes while inputing the info...

Maybe I'm making something wrong maybe its actually that or something.U sure u inputted everything correct?

Edit: I did a test too and got around 9k dV somehow with around the same things u said

How many different engines you have?If you have 2 different engines then you will do something like this to find whats an average isp:
(one hawk isp + one valiant isp)/2

 

[Astatium_209]

Maybe I'm making something wrong maybe its actually that or something.U sure u inputted everything correct?

Edit: I did a test too and got around 9k dV somehow with around the same things u said

How many different engines you have?If you have 2 different engines then you will do something like this to find whats an average isp:
(one hawk isp + one valiant isp)/2

Just one engine, very simple.

 

[Horus Lupercal]

an average isp:
(one hawk isp + one valiant isp)/2

That's because that isn't how average specific impulse works.

 

[Pink]

You need to include a weighing of each engine's thrust contribution.

Think about it logically.
Engine A has isp 1000s, thrust 0.1t.
Engine B has isp 500s, thrust 20t.

Logically, since engine A is making very little thrust, it is not making a big contribution to increased isp. The combined isp will not be 750s like your calculation says, it will be more like 501s.

But how to calculate? Include thrust in the formula.
Thrust*isp = fuel consumption.
The idea is to find the combined fuel consumption and thrust, in order to find combined isp.

Combined fuel consumption / combined thrust = combined isp.

If you do it right, you should get a combined isp of 502.5s for 1 engine A and 1 engine B working together.

 

[Searcher Space Agency]

You need to include a weighing of each engine's thrust contribution.

Think about it logically.
Engine A has isp 1000s, thrust 0.1t.
Engine B has isp 500s, thrust 20t.

Logically, since engine A is making very little thrust, it is not making a big contribution to increased isp. The combined isp will not be 750s like your calculation says, it will be more like 501s.

But how to calculate? Include thrust in the formula.
Thrust*isp = fuel consumption.
The idea is to find the combined fuel consumption and thrust, in order to find combined isp.

Combined fuel consumption / combined thrust = combined isp.

If you do it right, you should get a combined isp of 502.5s for 1 engine A and 1 engine B working together.

View attachment 61082

Well first thanks for the formula and stuff but I dont have a combined isp calculator in the code it just wants it as an input.But I may add it.

 

[Altaïr]

Thrust*isp = fuel consumption.

Not exactly. The correct formula is:
Isp = Thrust / (g × fuel consumption)

However the reasoning is correct, the global Isp can simply be calculated by taking into account the global thrust and the global fuel consumption.

Searcher Space Agency I use a spreadsheet myself that includes an Isp calculator. You'll find it here:
SFS 1.5 - Ship Design Assistant
It's in read-only mode, please make your own copy if you want to modify it.

You can take inspiration from it if you want.
Note that the formula I use is slightly different.

If FC is fuel consumption and Isp the specific impulse, the global Isp is:
Isp = (FC1×Isp1 + FC2×Isp2 + ...)/(FC1 + FC2 + ...)

The following also works:
Isp = (Thrust1 + Thrust2 + ...)/(g×(FC1 + FC2 + ...)

Those 2 formulas are equivalent.

 

[Pink]

Not exactly. The correct formula is:
Isp = Thrust / (g × fuel consumption)

Ahhh..... I love those oversights.

 

[Timmy]

I used this equation from the SFS wiki in my DeltaV calculator. It works.

where

is the force in kilonewtons of the n th engine, including duplicates

This is my caclulator