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Everything posted by RCgothic

  1. Nuclear engineer here. No, no fission reactor design can detonate like a nuclear explosion. When the reaction runs away out of control the fissionable material heats up, and there are several mechanisms by which that makes the fuel less reactive, bringing the reaction to a new equilibrium state. The fuel may melt, but if there's an explosion it's going to be as a result of other materials present in the core (hydrogen, steam, molten salt explosions). Designing a bomb to detonate (even to get it to fizzle) is very difficult. You need to convince most of the fuel to react before heat
  2. Tidally locked to a gas giant is not necessarily a problem, it just means very long days.
  3. Again, have to mention that RC rockets/ rockets with guidance computers are totally illegal in many jurisdictions because they can be used as missiles. You can just about get away with auto-stabilization, but seriously guys, don't get yourselves arrested. Contact your local NAR group for advice.
  4. Be aware that manufacturing solid rocket motors in the UK is illegal: "Under the conditions of the 1875 Explosives Act, the 1883 Amendment, and later Prevention of Terrorism acts, it is an offence to manufacture your own solid fuel rocket motors, since these are classed as an explosive." I don't know what the relevant US laws are. It's something to be aware of depending on where you're based.
  5. Wow, the Galactica's a beast! Following on from my previous attempt, I installed a docking port and an RCS system and attempted to hit some of the bonus achievements. Payload up, 1 xenon-electric probe sat: Launched: Docked to a space station: Ore probe for downlift (forgot to fill it - shh!) Ore probe docked: And landed at KSC for probe unloading: Full album: http://imgur.com/a/XyYWU The hitches were that I stuck the xenon-electric thruster on backwards, and forgetting to actually put any ore in my o
  6. Yes, that looks like a normal F1 concept to me?
  7. New entry for 1.2 before I reinstall FAR. Before Take Off: Full throttle: Take off Rocket mode engaged! Apoapsis established: Orbit acheived! Stayed up a few hours waiting for KSC Dawn: Beauty 1: Beauty 2: Reentry periapsis and fuel remaining: Coming in Hot: Coming in early: Final approach: Landed with 1000 units of fuel still onboard:
  8. I followed up the above post with a calc on the half-period of an orbit with apoapsis at oort and periapsis at sol. 2 million years. So that idea's out. Although imparting an initial velocity would massively reduce that, but the maths is escaping me at the moment.
  9. Much easier would be asteroid redirection. Eg Oort cloud objects don't orbit very fast - 3m/s ish. You could divert a very large object into the inner solar system and it would arrive at earth at approx 42km/s or even faster if it were slingshotted around Jupiter. Somebody check my maths on this, but a high performance ion thruster (exhaust velocity 5km/s) could halt the oort orbital velocity of a 10,000 ton object with 600kg of propellant. The sun would them do almost all the rest. If that could be brought in at 60km/s the kinetic yield would be 4 megatons, or 2 megatons without a s
  10. And that's just an argument for multiple colonies, not zero. Mars would actually be much less vulnerable to global catastrophe too. With power mainly from nuclear and enclosed habitats, there's not much an impact on the other side of the planet could do compared to a similar atmosphere-disturbing event on Earth.
  11. Earth could be rendered uninhabitable by any number of scenarios. In that situation humanity is saved by an offworld colony. Also, in a sufficiently large disaster, even with a 1-5% survival rate civilization on Earth would collapse. With all the easily extracted resources already extracted, there's no reason to assume advanced civilization could emerge again second time. An advanced society based on Mars could bootstrap us back into the space age. There are plenty of reasons why getting off this planet permanently is good for humanity's long term prospects.
  12. Centre of mass is the average position of all the masses in a body. It is always fixed unless you add/remove mass or allow those masses to move around with respect to one another. If the resultant force of all applied forces acts through the centre of mass the body will translate without rotation. Any resultant moment will cause the body to rotate about its CoM without translating unless there is also resultant force. Centre of Gravity is the average position of every mass weighted by the gravity field at the position of that mass. It is a concept that makes visualising resultant forces m
  13. Sure they will, compared to other Martians. It might not be rich by Earth standards, but that's a pretty irrelevant comparison when the nearest Earthling is an 80 day flight away. Who wouldn't want to have corporate/political/fiscal power over a significant fraction of a planet? When the colony is established it will have its own economy. Being top dog in that economy would be like being a big fish in a small pool, compared to being an irrelevant fish in an ocean. That's going to be an attractive investment to a certain type of person. It's trading Earth funds for Martian powe
  14. I would assume that the Spaceship is capable of blasting free of the booster if necessary. If there's a problem with the Spaceship itself there's probably nothing that can be done. You can't just ejector-seat 100 people, and the Spaceship doesn't contain parachutes because it lands propulsively. Any cabin detatchment would have jettisoned its means of landing safely. But at least its launch abort scenarios are likely to be more benign than the shuttle's.
  15. Also, whoever first gets a foot in the door on Mars is likely to end up being the richest person/company on Mars. That's not nothing, even if the investment doesn't return to Earth or the RoI is small by Earth standards.
  16. New Shepherd attains an apogee of what, 100km? That's 0.981MJ/kg specific energy to the payload at apogee, conservatively. Falcon 9 first stage separates at about the same height, but can be doing 8000km/h +. That's an additional 2.46MJ/kg specific energy, or 3.35MJ/kg total. So before even involving the difficulties of piloting to a remote landing site, energetically what SpaceX does is nearly 3.5 times harder. Ok, Blue Origin did it first. But it's like the difference between landing Freedom 7 and landing Apollo 8.
  17. The F1-B engine is part of one proposal for advanced kerolox boosters to replace the shuttle derived ones as part of... Block 2? There are other options as well.
  18. Except that when you hold your breath and that 14% residual volume expands 4x the pressure drops correspondingly to 1/4, which would then actively extract oxygen from your blood. Being a small volume, the partial pressures will equalise some, so it's not quite as bad as 3/4 of a total vacuum. But 60-75% as bad is still pretty bad.
  19. I misremembered. I found the Google report, it's actually 17 seconds to respond to alerts and take back control. To actually react intelligently is another matter entirely. The situation you describe sounds like a pilot with hands on anticipating the situation that they need to rectify. In an emergency whilst operating on automatic the manual operator may have been reading, snoozing, facing the wrong direction. They aren't going to have the situational awareness of an alert pilot anticipating that they're going to have Also 'often completed in less than five seconds' is not 'everyon
  20. Studies have shown it takes at least 12 seconds for a passenger to become adequately aware and in control in an emergency situation. Vehicle accidents happen so quickly that a manual override is totally useless. Yes, a system failure will lead to deaths. So you design a system that cannot fail catastrophically or with redundant back ups as much as possible. Automated vehicles will be orders of magnitude safer than manually operated ones. They don't get tired. They don't get distracted. They can look in every direction at once and see through light obstructions. They can
  21. Four engines. In the event of failure, two have sufficient power to stay aloft at max throttle, with the third providing trim for offset load. Obstacles and noise issues can be mostly avoided by a minimum height for non-vertical flight. Power lines in the UK aren't higher than 55m And anything taller than that would be both mapped (regulatory requirement) and detectable by the onboard collision avoidance system. Drones won't move as fast as aircraft, so the 200m mandatory minimum distance can probably be reduced. They'll also talk to each other to keep out of each other's way ideal
  22. Yet on screen evidence suggests it's safe enough to walk around in only a mask. That's either a goof or an indication that H2S is on the order of ppm. LCL0 is on the order of 600ppm (inhaled?) for 30 mins, or 800ppm for 5min. Max US regulatory exposure is 20ppm (inhaled?). Lung surface area is approx 25 times greater than skin surface area (conservatively). It's also thinner and more readily diffused across. It therefore stands to reason that a lethal inhaled concentration of ~800ppm atmospheric equates to less than the regulatory equivalent skin dose. Put another way, the conc
  23. Sorta. If you're in a plane or spaceship that depressurises it's a bad idea to hold your breath because the pressure in your lungs will dangerously over-inflate them without external pressure on your chest. And then once you've breathed out the zero/near zero partial pressure of oxygen in your lungs causes the oxygen in your blood to diffuse out down the pressure gradient and you've got 30s. It's actually a similar situation if you find yourself in an atmosphere at sea level composed of pure nitrogen, carbon dioxide, or other composition with zero oxygen concentration. Breathing norm
  24. Nasa is doing well in the probe department. NASA is not doing well in the manned spaceflight department. Even if SLS/Orion avoids cancellation they have far too few missions planned. This area currently feels anaemic and weak. SpaceX has done a fine job recovering 4 boosters and have designed a damn fine kerolox engine in the Merlin 1D.
  25. The Falcon 9.1 FT is the coolest rocket because it uses super-cryogenic propellants.
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