Fuel Tank Calculator

[opensesame11]

This is the first thing I've made for KSP, and I plan to make it into an addon, but for now, it's just a quick C++ program that runs off of the command line.

It uses the rocket equation to tell you how many liters of liquid fuel you need to add to your craft to give it a target amount of delta v.

This is useful if you want to drop extra tanks at each milestone, like a landing or escaping an SOI or something similar.

Without any more hesitation, here it is.

I don't think the temporary file host I'm using will keep it for very long, so I'll try to move it to SourceForge.

Also, I haven't really tested it on any other systems yet, but since I made it in visual studio 2010 express, it will probably whine and complain of you don't have VC++2010 Redistributable pack, so download it if you get an error like that.

Have fun with your new knowledge.

[Creat]

Uhm, you're aware that things like Kerbal Engineer (and MechJeb I think) simply tell you how much delta-v you have, and will update as you add tanks?

It will also correctly handle stages and show you correct delta-v for each stage (including when a certain stage only drops tanks, for example).

I think I'm just not getting a specific scenario for where this is needed as opposed to the Kerbal Engineer implementation?

Edit: from what I've seen when I tried it, couldn't you do the same thing (probably better organized) in an Excel/OO-Calc sheet?

[opensesame11]

Uhm, you're aware that things like Kerbal Engineer (and MechJeb I think) simply tell you how much delta-v you have, and will update as you add tanks?

It will also correctly handle stages and show you correct delta-v for each stage (including when a certain stage only drops tanks, for example).

I think I'm just not getting a specific scenario for where this is needed as opposed to the Kerbal Engineer implementation?

Edit: from what I've seen when I tried it, couldn't you do the same thing (probably better organized) in an Excel/OO-Calc sheet?

Yes, I'm aware of Kerbal Engineer and MechJeb, though while they may be dynamic, you have to guess the amount of fuel to add and then check if you've fallen short, met or surpassed your target delta-v, where my tool (which would be useful mostly in the game, as the time to alt tab and start it up would outweight the benefits as opposed to Kerbal Engineer) will give you an exact amout of fuel in liters.

In terms of usability, this isn't very good. It's a 20 some line program that I threw together because maybe someone else needed a calculator that does this. I plan to make it more user friendly, but the bulk of my efforts went to the mathematics. Any one can plug starting weight, ending weight and Isp into the rocket equation, but this gives you the exact number of litres you need accounting for the addition of fuel tank weight.

A spreadsheet at this point in time would be essentially the same level of efficiency. My program uses a few std::cin s and std::cout s for io, so I could do better. I hope this answers your confusion. Please feel free to ask any more questions, because I'm not really good at answering them properly.

[opensesame11]

Here's the formula:

Startingweight=(e^(deltaV/(Isp*9.81))-1)/(9-e^(deltaV/(Isp*9.81)))*payload*9+payload

Subtract payload to get the weight of the fuel apparatus. Divide by 9 to get the mass of the empty fuel tanks.