Category Archives: Uncategorized

Getting My Numbers

This is an explanation of how I get BOTE numbers for such things as the comparison between LH2 and CH4 propellants as in Jons’ last post. The focus Jon had was how much H2 do you need to carry to … Continue reading

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Semi-Staged Combustion

It is interesting comparing the two best known first stages in the US that use kerosene and LOX. The Atlas 5 and the Falcon 9 use a similar fuel in their first stages and then diverge in the technical aspects. … Continue reading

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Electric Inducer Pump

It takes pressure in the tank to suppress cavitation in the pumps for rocket engines. It is customary to use helium for most pressurization due to its’ low molecular weight. Unfortunately, it can take a lot of helium in some … Continue reading

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Notchbell Nozzle

Several years back I suggested a type of compensating nozzle that should be inexpensive to build and test. Unfortunately the ones I made for demonstration with compressed air were hit and miss as I didn’t have the theory quite right. … Continue reading

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Old Engines

Some before, and many after the accident criticized the use of old engines for the Antares. Many references were made to the long storage time with some mention of them as antiques. The refurbishment of these engines didn’t seem to … Continue reading

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Working full time on the Martian surface is within US Radiation Worker limits

The US Radiation Worker annual radiation limit is 5 rem, or 50mSv/year. Divided into the 2000 annual working hours, that’s 0.025mSv/hour. The Mars Curiosity rover measured an average dosage on Mars of 0.67mSv/day at about -4km altitude. That’s 0.028mSv/hour. If … Continue reading

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Homo Cosmicus: Vestibular Implants

EDIT: David Birchler mentioned in the comments that an implant is not required. The technology is called galvanic vestibular stimulation and it can stimulate the sensation of pitch, roll, and yaw. Since surgery is not required, it sounds like this … Continue reading

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Perfectly energy-efficient rocket vehicle

So I was watching a video of a talk by Geoffrey Landis (my old mentor when I was an intern at Glenn), and he made a very interesting point. If you’re trying to maximize energy efficiency for a rocket and … Continue reading

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Reusable Falcon Heavy payload (upper stage staging velocity)

Jon and I were discussing the recent Falcon Heavy payload numbers. Expendable performance to GTO is supposed to be 22 tons (metric, same for the rest of this post). Given how aggressive that is, and given the history of Falcon … Continue reading

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Fundamental cost of putting stuff in orbit: theoretical minimum vs RLV

What is the minimum energy of orbit, and how does that compare to the energy in a chemical rocket’s propellant? Accessing a 150km LEO orbit requires first the energy to get to 150km. That’s roughly (in Energy/mass, or J/kg, aka … Continue reading

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