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Posts posted by RCgothic

  1. There is zero requirement for a man-rated superheavy launcher.

    You don't need a superheavy to put a crew in orbit, and you don't need to man-rate a cargo superheavy and make everything five times more expensive than it needs to be.

    RS-25 only had to be uprated because of the poor launcher architecture. Does Raptor need to withstand the heat and vibration of solid boosters? No, it doesn't. Because raptor will only fly on competently designed vehicles. 

  2. If a flight is only 20 minutes and it involves anything close to a full g or greater, there won't be any bathrooms. In the first instance, the trip isn't long enough for them to be necessary and in the second it won't be safe for people to move about the cabin.

  3. Yeah, propellors and wings are both aerofoils. They both create thrust by deflecting quantities of air by Newton's third law. An understanding of Bernoulli just allows you to design shapes that do so efficiently.

    There's no special distinction for propellors or turbine blades. They just have twist and chord variation to compensate for the varying effective velocity vector of the incident airflow over the aerofoil due to the circumferential speed of the blade varying from the root to the tip. 

  4. You learn more from your failures. At least this was a non-mission-critical failure.

    The side cores did look very much like a RUD. I think it was the infra-red camera getting super-saturated by the exhaust gases, causing the landing burn to look more spectacular than usual!

  5. 1 hour ago, Spacescifi said:


    Just accept the effect as a plot device, shielding the vessel from gravity. It can be turned on or off. Which makes it useful for reaching space, and then the ship can reach orbital velocity and shut it off.

    Or don't turn it off and just hover. If the device uses less energy to run than it would take to accelerate to orbital velocities, you just wouldn't.


    And if it does use more energy than it takes to get to orbital speed, might not be worth having it at all. The ascent is a relatively small part of the energy requirement for accelerating to orbital speed.

  6. UK radio today reporting that tourist flights to the international space station were to be offered for £28,000. The news was lacking in detail, but that's insane. Even starship with a capacity 100 would struggle to loft a person into LEO for so little.

  7. If a ship can avoid experiencing gravity it can maintain an orbital altitude without an orbital velocity. In fact, it *needs* to experience gravity in order to orbit, because without gravity any velocity is escape velocity unless you apply constant radial thrust. A gravity manipulating ship doesn't have to orbit unless it wants to. It levitates.

    So there's no reason its entry to the atmosphere needs to be great other than reducing transit time. If you can sustain re-entry heating, come in hot. If not, walking pace or slower will do.

    Without gravity all urgency goes away.

  8. On 4/23/2019 at 4:38 PM, mikegarrison said:

    I wonder if steam locomotives were intentionally designed so that the front plate was the weakest point in the pressure vessel? I mean, you don't want them to explode, but if they do explode, then that's probably the safest way for them to explode.

    Well first off they were usually designed with redundant steam relief valves to stop that happening. Of the fifteen boiler explosions in the UK in the 20th century, only two were failures of the boiler barrel due to incorrectly assembled relief valves (overpressure).

    Thirteen were due to weakening of the firebox caused by low water level, which is not quite so spectacular. Low water level is caused by either operator error or faulty water level gauges.