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1

OKEANOS was a JAXA project of circa 2010, combining a solar sail and an ion engine. Authors were going to send it to Jupiter's trojan asteroids with a possible sample-return trip to Earth. The sail would have been made of a 10 μm-thick polyimide film measuring 40 × 40 meters (1,600 $m^2$) covered with 30,000 solar panels 25 μm thick, capable of generating ...

4

From my (probably) similarily rough understanding of L*, it's a minimum size required for propellants to stay long enough in the chamber to mix properly. If the distance is shorter than that, you will experience problems with combustion instability. As such, having a length that's too large is certainly not as bad as too short, although the engine is then ...

7

This is the same or similar unphysical stuff as before. Then for 40W power inside cavity, the calculated Thrust T=20.44mN. There is no propellant here. If 40 Watts were in the form of photons, then the thrust would be $P/c$ = 133 nanoNewtons. This generates 105 more momentum per unit time that it's allowed to. What's the final word; does the EmDrive ...

2

Although I agree with Organic Marble that open expander cycles should most likely split the fuel before the cooling jacket, there are some examples where this isn't the case. For example in the RD0146 there is a split of the fuel line after the cooling jacket (see image), although this is just to power the fuel boost pump (so in essence it is more a closed ...

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