I need to move freight from Venus' atmo to orbit. Over a year ago I'd run low-orbit calculations just for the delta-V. Earlier this month I was talking about a ferry from a reasonably-high Venus orbit into 100 km altitude which is 6150 km pericytheree. From a solar-system perspective the latter is more useful. How fast is that ferry going in Venus' atmo?
Luckily I do find the gravitational parameter μ of Venus... in meters. 3.24859E+14 if my other inputs are in meters.
At 100 km any satellite does aerobraking but, Venus Express told us, not much. The VEx was ranging 250-66000 km altitude at eccentricity 0.84. Math.Sqrt(3.24859E+14 * (2.0/6300000 - 2.0/(72000000 + 6300000))) should have been 9740 m/s at peri'. I won't lose by running mine a bit lower and more circularly; 20000 km semimajor would be 9455 m/s, nu?
By reference Mach One is 343 m/s. So Venus Express, at its low point, was running over Mach Twentyeight. Ramjets, ranging Mach 3-6 here, should range from 1-2 km/s. They go faster at lower air-pressures but we haven't much tested these altitudes over Earth; if they fly too fast for too long they fly too FAR, over other countries' airspace. We can fly a Pluto ramjet for some time over Venus. This jet wasn't fast enough for my 2020 low-orbit; it's even worse for my 2021 ellipse.
I want thrice times Mach Nine. UPDATE 5/17: Earth is looking to Mach Seventeen.
Venus might need to develop that combustion ramjet, the "scramjet" so called. These are barely out of the planning stages here on Earth in part because for any duration, as mentioned, they need a good distance to move through (and too many people listen to concern-trolls). UPDATE 2/24: Molten-core Pluto?
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