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Why does my spaceplane have less than half fuel on start?


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Hello everyone! I made a spaceplane, and wanted to launch. It has two turbojet engines and one jet engine. However, when I launch it, the fuel is half gone, and it has not flown at all! Why is this? Do I need more intakes? Thanks! :)

Picture: http://postimg.org/image/bx02dhwp3/

Edited by CaptainApollo
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  CaptainApollo said:
Why not? It is more efficient for fuel, is it not? :D

ISP is an indicator of fuel efficiency for thrust. What most people care about for jets is fuel efficiency for distance. The common approach to that is to fly high and fast. Flying high lowers drag and thus the thrust needed to maintain speed. Flying fast means that you consume less fuel per distance because you cover it faster.

A single turbo jet super cruises at 1 km/s for .15-.25 fuel drain rate. A basic jet does 200 m/s for around .06 fuel drain rate.

0.25/1000 = 0.00025 < 0.0003 = 0.06/200.

Under those conditions, the turbo is more efficient. Even if my fuel drain for basic jet is off, the speed advantage is it's own reward. Also flying high gives you massive potential energy. You can glide the last 500 km of flight on no fuel!

Unless you do a lot of low altitude flight, turbo jets tend to be better on whole when you balance all concerns.

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Also, the mk2 tanks you're using are marked as LFO tanks. Your plane doesn't appear to have any rockets on it, so you don't need any oxidizer. Try switching those to just the liquid fuel tanks. They're lighter and hold more of the fuel you actually need.

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