Kerbal Space Program - Tiniest Mun Rocket Part I

Channel:

Robert Dodd

Subscribers:

1,010

Published on September 14, 2012 4:52:32 AM ● Video Link: https://www.youtube.com/watch?v=ehog7NO7IrI

Game:

Kerbal Space Program (2015)

Duration: 13:16

3,855 views

10

I like a big rocket as much as the next person. Sometimes I suddenly shout into the night, "Moar Boosters!", flinging sweat from my frenzied brow.

I am happy to see you, but yes there is a rocket in my pocket. ;)

Okay, I realize that all sounded slightly lewd. ;) We're talking liquid fueled spacecraft here, get your mind out of the gutter. ;)

However, you don't need a big rocket to get to the Mun or Minmus. In many ways, smaller is better. The smarter you design your rocket, the more you can do with a smaller rocket, and conversely it is perfectly possible to build a gigantic rocket with gigantic engines that will never make orbit, because it is just too heavy to lift itself there. In this video, we take a very small spacecraft indeed to the Mun and back to Kerbin with much fuel to spare. You too can build such spacecraft keeping in mind these basic fundamental principles:

1. Weight to Thrust Ratio
(maximum thrust of all engines) / (mass units x 10) = thrust to weight ratio

A 1:1 thrust ratio means you are probably just short of lifting off the ground. A 2:1 ratio is better. 3:1 even better and so on. If you have a bazillion heavy tanks on the first stage of your rocket, it doesn't matter how big your first stage rocket engine is, it won't perform right or at all.

2: Know the weight to thrust ratio of your engines, and the weight to fuel ratio of your fuel tanks.

With fuel tanks, your evaluation of them is very simple: the more units of fuel you get for one unit of mass, the better. With rocket engines, the weight of the rocket engine is not the only factor to take into consideration, but it is one factor. You also have to factor in their fuel efficiency, which in some cases is measured as burn rate and in other instances in specific impulse. Except for the aerospike engine, every engine is either more efficient in the atmosphere or more efficient in vacuum, and the higher the specific impulse number, the more efficient it is in using fuel.

3. Unfired engines are just dead weight.

In a perfect world (with a few exceptions), every rocket engine you have would be firing at full blast at liftoff. If you have a five stage rocket, and only the first stage is firing at first, you will have several mass units of just dead weight. Instead of arranging your stages to drop off the bottom of the rocket, arrange them to drop off the sides of the rocket. It's okay to have one upper stage perhaps that isn't firing at liftoff, but other than that every rocket engine you have on your rocket that isn't firing isn't carrying its weight at that moment. It so happens that my Tiniest Mun Rocket has one stage that isn't firing at liftoff, but that is because I am trying to take advantage of the extreme fuel efficiency of jet engines in the atmosphere. You may have other kinds of engines, such as nuclear engines, that will be very wasteful or ineffective in the atmosphere but very efficient in a vacuum. Those would be two cases when you can ignore this rule to an extent.

If you don't have Kerbal Space Program yet, what are you waiting for? Christmas? New Years? Mayan Apocalypse? Get it, get it now, obey. ;) The demo is free and buying the alpha version with automatic upgrades to the full version is pretty cheap at the moment, but once the game hits version 1, the price will go up. So you buy it now, you get all updates up to and including the full game at no extra cost once the full version is completed, and you get it cheaper than you would if you buy the full version when it comes out. And even though it is still in alpha testing, it's a blast to play. Can't beat that. ;)

http://kerbalspaceprogram.com/

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