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NewsHow to find career happiness: Stop chasing the money Pin
Kent Sharkey19-Jul-15 18:08
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NewsWhat makes a great developer? Pin
Kent Sharkey19-Jul-15 18:07
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GeneralRe: What makes a great developer? Pin
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TheGreatAndPowerfulOz20-Jul-15 5:24
TheGreatAndPowerfulOz20-Jul-15 5:24 
NewsThis company aims to launch rockets with beams of power Pin
Kent Sharkey19-Jul-15 17:42
staffKent Sharkey19-Jul-15 17:42 
GeneralRe: This company aims to launch rockets with beams of power Pin
Daniel Pfeffer19-Jul-15 19:12
professionalDaniel Pfeffer19-Jul-15 19:12 
GeneralRe: This company aims to launch rockets with beams of power Pin
enhzflep19-Jul-15 19:21
enhzflep19-Jul-15 19:21 
GeneralRe: This company aims to launch rockets with beams of power Pin
Dan Neely20-Jul-15 3:47
Dan Neely20-Jul-15 3:47 
All of that's true (although the bit about the changing volume of a solid fuel rocket's combustion chamber's irrelevant to this design); but that bit that you're missing is that staging adds a huge amount of complexity to designs and is something that we only do because the low specific impulses of current rocket fuels mean we have no choice.

Specific impulse is a term that goes in the exponent if you're calculating the mass fraction of a rocket that needs to be made of fuel to reach it's destination; which means that even fairly modest increases to it will result in large shifts in the mass fraction.

Pulling the equations out of wikipedia[^] gives the mass fraction as: 1-e^(-delta_v/v_effective), and v_effective = g * i_sp For a low earth orbit you need a delta v of 7000 m/s; plugging the numbers into google gives a theoretical mass fraction of 0.91[^] for fuel with a specific impulse of 300 seconds (typical for a hydrocarbon fueled rocket), 0.81[^] for a Isp of 425 (hydrogen fueled rocket), an Isp 600 would improve the ration to 0.69[^].

With conventional liquid fueled rockets, that's roughly the same as the ratio between the first stage of the rocket and everything else; which is why the performance numbers they're expecting actually do make an SSTO a viable design.

Keeping the beam from the radar array tight enough to avoid wasting most of the power is potentially a major challenge; however beyond the general rule that a larger phased array makes a tighter beam possible I don't know enough about their design to make an estimates of how feasible this would be.
Did you ever see history portrayed as an old man with a wise brow and pulseless heart, waging all things in the balance of reason?
Is not rather the genius of history like an eternal, imploring maiden, full of fire, with a burning heart and flaming soul, humanly warm and humanly beautiful?
--Zachris Topelius

Training a telescope on one’s own belly button will only reveal lint. You like that? You go right on staring at it. I prefer looking at galaxies.
-- Sarah Hoyt

GeneralRe: This company aims to launch rockets with beams of power Pin
enhzflep20-Jul-15 4:32
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NewsIoT and Developers: Is reality meeting expectation? Pin
Kent Sharkey19-Jul-15 17:38
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NewsMandatory Windows 10 Home updates: The good, the bad, and the potentially ugly Pin
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GeneralRe: Mandatory Windows 10 Home updates: The good, the bad, and the potentially ugly Pin
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GeneralRe: Mandatory Windows 10 Home updates: The good, the bad, and the potentially ugly Pin
Member 1168325120-Jul-15 3:45
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GeneralRe: Mandatory Windows 10 Home updates: The good, the bad, and the potentially ugly Pin
Dan Neely23-Jul-15 3:04
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GeneralRe: Mandatory Windows 10 Home updates: The good, the bad, and the potentially ugly Pin
Member 1168325124-Jul-15 3:23
Member 1168325124-Jul-15 3:23 
GeneralRe: Mandatory Windows 10 Home updates: The good, the bad, and the potentially ugly Pin
Dan Neely25-Jul-15 10:09
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NewsLatest Flash Player version has improved exploit defenses Pin
Kent Sharkey19-Jul-15 17:27
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Patrice T20-Jul-15 5:54
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NewsFor the first time in 12 years, less than half of emails are spam Pin
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TheGreatAndPowerfulOz20-Jul-15 5:23
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NewsAll editions of Windows 10 get 10 years of updates, support Pin
Kent Sharkey19-Jul-15 17:23
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irneb19-Jul-15 23:10
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GeneralRe: All editions of Windows 10 get 10 years of updates, support Pin
Kevin McFarlane20-Jul-15 0:09
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NewsSan Francisco techies are hiring this Wiccan witch to protect their computers from viruses and offices from evil spirits Pin
Kent Sharkey19-Jul-15 17:15
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